README
¶
= go-getoptions
David Gamba, https://github.com/DavidGamba
:idprefix:
:name: go-getoptions
:toc: macro
:toclevels: 4
Go option parser inspired on the flexibility of Perl’s GetOpt::Long.
image:https://godoc.org/github.com/DavidGamba/go-getoptions?status.svg[link="http://godoc.org/github.com/DavidGamba/go-getoptions"]
image:https://travis-ci.org/DavidGamba/go-getoptions.svg?branch=master["Build Status", link="https://travis-ci.org/DavidGamba/go-getoptions"]
image:https://codecov.io/github/DavidGamba/go-getoptions/coverage.svg?branch=master["Coverage via Codecov", link="https://codecov.io/github/DavidGamba/go-getoptions?branch=release"]
toc::[]
[[quick_overview]]
== Quick overview
. Define your command line specification:
+
[source,go]
----
package main
import (
"fmt"
"io/ioutil"
"log"
"os"
"github.com/DavidGamba/go-getoptions"
)
var logger = log.New(ioutil.Discard, "DEBUG: ", log.LstdFlags)
func main() {
var debug bool
var greetCount int
var list map[string]string
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("h", "?"))
opt.BoolVar(&debug, "debug", false)
opt.IntVar(&greetCount, "greet", 0,
opt.Required(),
opt.Description("Number of times to greet."))
opt.StringMapVar(&list, "list", 1, 99,
opt.Description("Greeting list by language."))
remaining, err := opt.Parse(os.Args[1:])
if opt.Called("help") {
fmt.Fprintf(os.Stderr, opt.Help())
os.Exit(1)
}
if err != nil {
fmt.Fprintf(os.Stderr, "ERROR: %s\n\n", err)
fmt.Fprintf(os.Stderr, opt.Help(getoptions.HelpSynopsis))
os.Exit(1)
}
// Use the passed command line options... Enjoy!
if debug {
logger.SetOutput(os.Stderr)
}
logger.Printf("Unhandled CLI args: %v\n", remaining)
// Use the int variable
for i := 0; i < greetCount; i++ {
fmt.Println("Hello World, from go-getoptions!")
}
// Use the map[string]string variable
if len(list) > 0 {
fmt.Printf("Greeting List:\n")
for k, v := range list {
fmt.Printf("\t%s=%s\n", k, v)
}
}
}
----
. Call it:
+
.Show help
----
$ ./myscript --help
SYNOPSIS:
myscript --greet <int> [--debug] [--help|-h|-?] [--list <key=value>...]...
REQUIRED PARAMETERS:
--greet <int> Number of times to greet.
OPTIONS:
--debug (default: false)
--help|-h|-? (default: false)
--list <key=value>... Greeting list by language. (default: {})
----
+
.Show errors
----
$ ./myscript
ERROR: Missing required option 'greet'!
SYNOPSIS:
myscript --greet <int> [--debug] [--help|-h|-?] [--list <key=value>...]...
----
+
.Show errors
----
$ ./myscript -g
ERROR: Missing argument for option 'greet'!
SYNOPSIS:
myscript --greet <int> [--debug] [--help|-h|-?] [--list <key=value>...]...
----
+
.Use of int option
----
$ ./myscript -g 3
Hello World, from go-getoptions!
Hello World, from go-getoptions!
Hello World, from go-getoptions!
----
+
.Use of bool option
----
$ ./myscript --debug -g 1 other stuff
DEBUG: 2019/07/14 23:20:22 Unhandled CLI args: [other stuff]
Hello World, from go-getoptions!
----
+
.Use of map option
----
./myscript -g 0 -l en='Hello World' es='Hola Mundo'
Greeting List:
en=Hello World
es=Hola Mundo
----
== Examples
=== Simple script
A simple script link:./examples/myscript/main.go[]
To use the autocompletion, cd to the link:./examples/myscript[] dir and run: `source sourceme.bash`
The run `go build` and `./myscript`.
Tab completion for this script is triggered for options only, so you need to have a dash `-` to trigger it: `./myscript -<tab><tab>`
=== Program with multiple commands separated in multiple packages
This is the other extreme, a large program that can separate each command in a separate go package.
The base is located at link:./examples/mygit/main.go[]
The commands are located at:
* link:./examples/mygit/log/log.go[]
* link:./examples/mygit/show/show.go[]
* link:./examples/mygit/slow/slow.go[]
To use the autocompletion, cd to the link:./examples/mygit[] dir and run: `source sourceme.bash`
The run `go build` and `./mygit`.
Tab completion without arguments triggers completion for commands, for option completion add a dash `-` and trigger it: `./mygit -<tab><tab>`
The link:./examples/mygit/slow/slow.go[slow] command shows an example of an slow command that can be cancelled with `Ctrl+C`.
The cancellation is passed to the command through `context.Context` and it is handled at the command to stop taking new work and trigger a cleanup routine.
Running `Ctrl+C` twice cancels the cancellation routine and fully cancels the program.
=== Directed Acyclic Graph Build System
This example shows task dependency orchestration and parallelization link:./examples/dag/main.go[].
To use the autocompletion, cd to the link:./examples/dag[] dir and run: `source sourceme.bash`
The run `go build` and `./dag`.
Tab completion without arguments triggers completion for commands, for option completion add a dash `-` and trigger it: `./dag -<tab><tab>`
== DAG Build System
For an overview of the Directed Acyclic Graph Build System see link:./dag/README.adoc[]
== Features
• Built in auto completion.
A single line of bash is all it takes.
• Allow passing options and non-options in any order.
• Support for `--long` options.
• Support for short (`-s`) options with flexible behaviour (see the <<operation_modes>> section for details):
- Normal (default)
- Bundling
- SingleDash
• `Called()` method indicates if the option was passed on the command line.
• Multiple aliases for the same option. e.g. `help`, `man`.
• `CalledAs()` method indicates what alias was used to call the option on the command line.
• Simple synopsis and option list automated help.
• Boolean, String, Int, Float64, Slice and Map type options.
• Negatable Boolean options.
+
For example: `--verbose`, `--no-verbose` or `--noverbose`.
• Options with Array arguments.
The same option can be used multiple times with different arguments.
The list of arguments will be saved into an Slice.
• Options with array arguments and multiple entries.
+
For example, instead of writing:
`color --r 10 --g 20 --b 30 --next-option`
or
`color --rgb 10 --rgb 20 --rgb 30 --next-option`
the input could be:
`color --rgb 10 20 30 --next-option`
• When using integer array options with multiple arguments, positive integer ranges are allowed.
+
For example, Instead of writing:
`csv --columns 1 2 3`
or
`csv --columns 1 --columns 2 --columns 3`
The input could be:
`csv --columns 1..3`
• Options with Key Value arguments.
This allows the same option to be used multiple times with arguments of key value type.
+
For example: `rpmbuild --define name=myrpm --define version=123`
• Options with key value arguments and multiple entries.
+
For example, instead of writing:
`connection --server hostname=serverIP --server port=123 --client hostname=localhost --client port=456`
the input could be:
`connection --server hostname=serverIP port=123 --client hostname=localhost port=456`
• Supports command line options with '='.
+
For example: You can use `--string=mystring` and `--string mystring`.
• Allows passing arguments to options that start with dash `-` when passed after equal.
+
For example: `--string=--hello` and `--int=-123`.
• Supports passing `--` to stop parsing arguments (everything after will be left in the `remaining []string`).
• Options with optional arguments.
If the default argument is not passed the default is set.
+
For example: You can call `--int 123` which yields `123` or `--int` which yields the given default.
• Allows abbreviations when the provided option is not ambiguous.
+
For example: An option called `build` can be called with `--b`, `--bu`, `--bui`, `--buil` and `--build` as long as there is no ambiguity.
In the case of ambiguity, the shortest non ambiguous combination is required.
• Support for the lonesome dash "-".
To indicate, for example, when to read input from STDIO.
• Incremental options.
Allows the same option to be called multiple times to increment a counter.
• Supports case sensitive options.
For example, you can use `v` to define `verbose` and `V` to define `Version`.
• Support indicating if an option is required and allows overriding default error message.
• Errors exposed as public variables to allow overriding them for internationalization.
• Supports program commands (when a command is passed a command function is triggered to handle the command logic).
• Built in `opt.Dispatch` function calls commands and propagates context, options, arguments and cancellation signals.
• Multiple ways of managing unknown options:
- Fail on unknown (default).
- Warn on unknown.
- Pass through, allows for commands and can be combined with Require Order.
• Require order: Allows for commands. Stop parsing arguments when the first non-option is found.
When mixed with Pass through, it also stops parsing arguments when the first unmatched option is found.
• Set options by reading Environment Variables.
== How to install it
. Get it from github:
+
`go get github.com/DavidGamba/go-getoptions`
. Then import it:
+
`import "github.com/DavidGamba/go-getoptions" // As getoptions`
. Enjoy!
== Dependencies
Go 1.14+
Only the last two versions of Go will be supported.
== Introduction
NOTE: For a <<quick_overview>>, jump to that section in the TOC or review the http://godoc.org/github.com/DavidGamba/go-getoptions[GoDoc Documentation].
Option parsing is the act of taking command line arguments and converting them into meaningful structures within the program.
An option parser should support, at least, the following:
=== Boolean options
`True` when passed on the command line.
For example:
`ls --all`
In `go-getoptions` this is accomplished with:
- `ptr := opt.Bool(name, default_value)`.
- `opt.BoolVar(&ptr, name, default_value)`.
- Additionally, if all you want to know is if the option was passed you can use: `opt.Bool(name, default_value)` (without capturing its return value) and then check `opt.Called(name)`.
- Also, you can get the value with `v, ok := opt.Value(name).(bool)`.
=== Options with String arguments
The option will accept a string argument.
For example:
`grepp --ignore .txt`
Additionally, arguments to options can be passed with the `=` symbol.
`grepp --ignore=.txt`
In `go-getoptions` this is accomplished with:
- `ptr := opt.String(name, default_value)`.
- `opt.StringVar(&ptr, name, default_value)`.
The features listed above are enough to create basic programs but an option parser should do better:
=== Options with Integer arguments
Parse an option string argument into an Integer and provide an user error if the string provided is not an integer.
For example:
`grepp --contex-lines 3`
and:
`grepp --context-lines string`
Error: 'string' is not a valid integer.
In `go-getoptions` this is accomplished with:
- `ptr := opt.Int(name, default_value)`.
- `opt.IntVar(&ptr, name, default_value)`.
=== Options with Floating point arguments
Parse an option string argument into a Floating point value and provide an user error if the string provided is not a valid floating point.
For example:
`program --approximation 3.5`
and:
----
$ program --approximation string
Error: 'string' is not a valid floating point value.
----
In `go-getoptions` this is accomplished with:
- `ptr := opt.Float64(name, default_value)`.
- `opt.Float64Var(&ptr, name, default_value)`.
The features listed above relieve the programmer from the cumbersome task of converting the option argument into the expected type.
That covers the most basic set of features, but still it is not enough to get past a basic program.
The following features will allow for a more complete interface.
=== Options with array arguments
This allows the same option to be used multiple times with different arguments.
The list of arguments will be saved into a Slice inside the program.
For example:
`list-files --exclude .txt --exclude .html --exclude .pdf`
In `go-getoptions` this is accomplished with:
- `ptr := opt.StringSlice(name, 1, 1)`.
- `opt.StringSliceVar(&ptr, name, 1, 1)`.
- `ptr := opt.IntSlice(name, 1, 1)`.
- `opt.IntSliceVar(&ptr, name, 1, 1)`.
`go-getoptions` has only implemented this feature for string and int.
=== Options with Key Value arguments
This allows the same option to be used multiple times with arguments of key value type.
For example:
`rpmbuild --define name=myrpm --define version=123`
In `go-getoptions` this is accomplished with:
- `strMap := opt.StringMap(name, 1, 1)`.
- `opt.StringMapVar(&ptr, name, 1, 1)`.
`go-getoptions` has only implemented this feature for string.
The features above are useful when you have a variable amount of arguments, but it becomes cumbersome for the user when the number of entries is always the same.
The features described below are meant to handle the cases when each option has a known number of multiple entries.
=== Options with array arguments and multiple entries
This allows the user to save typing.
For example:
Instead of writing: `color --r 10 --g 20 --b 30 --next-option` or `color --rgb 10 --rgb 20 --rgb 30 --next-option`
The input could be: `color --rgb 10 20 30 --next-option`.
The setup for this feature should allow for the user to continue using both versions of the input, that is passing one argument at a time or passing the 3 arguments at once, or allow the setup to force the user to have to use the 3 arguments at once version.
This is accomplished with the minimum and maximum setup parameters.
The minimum setup parameter indicates the minimum amount of parameters the user can pass at a time.
For the example above, the parameter could be set to 3 to force the user to have to pass the 3 arguments at once.
When set to 1, the user will be able to pass a single parameter per option call.
The maximum setup parameter indicates the maximum amount of parameters the user can pass at a time.
The option parser will leave any non option argument after the maximum in the `remaining` slice.
In `go-getoptions` this is accomplished with:
- `strSlice := opt.StringSlice(name, minArgs, maxArgs)`.
- `opt.StringSliceVar(&ptr, name, minArgs, maxArgs)`.
- `intSlice := opt.IntSlice(name, minArgs, maxArgs)`.
- `opt.IntSliceVar(&ptr, name, minArgs, maxArgs)`.
Additionally, in the case of integers, positive integer ranges are allowed.
For example:
Instead of writing: `csv --columns 1 2 3` or `csv --columns 1 --columns 2 --columns 3`
The input could be: `csv --columns 1..3`.
In `go-getoptions` this is currently enabled by default when using:
- `intSlice := opt.IntSlice(name, minArgs, maxArgs)`
- `opt.IntSliceVar(&ptr, name, minArgs, maxArgs)`.
=== Options with key value arguments and multiple entries
This allows the user to save typing.
For example:
Instead of writing: `connection --server hostname=serverIP --server port=123 --client hostname=localhost --client port=456`
The input could be: `connection --server hostname=serverIP port=123 --client hostname=localhost port=456`
In `go-getoptions` this is accomplished with:
- `strMap := opt.StringMap(name, minArgs, maxArgs)`.
- `opt.StringMapVar(&ptr, name, minArgs, maxArgs)`.
That covers a complete user interface that is flexible enough to accommodate most programs.
The following are advanced features:
=== Stop parsing options when `--` is passed
Useful when arguments start with dash `-` and you don't want them interpreted as options.
In `go-getoptions` this is the default behaviour.
=== Stop parsing options when a command is passed
A command is assumed to be the first argument that is not an option or an argument to an option.
When a command is found, stop parsing arguments and let a command handler handle the remaining arguments.
For example:
`program --opt arg command --subopt subarg`
In the example above, `--opt` is an option and `arg` is an argument to an option, making `command` the first non option argument.
Additionally, when mixed with _pass through_, it will also stop parsing arguments when it finds the first unmatched option.
In `go-getoptions` this is accomplished with:
- `opt.SetUnknownMode(getoptions.Pass)`.
And can be combined with:
- `opt.SetRequireOrder()`.
=== Allow passing options and non-options in any order
Some option parsers force you to put the options before or after the arguments.
That is really annoying!
In `go-getoptions` this is the default behaviour.
=== Allow pass through
Have an option to pass through unmatched options.
Useful when writing programs with multiple options depending on the main arguments.
The initial parser will only capture the help or global options and pass through everything else.
Additional argument parsing calls are invoked on the remaining arguments based on the initial input.
In `go-getoptions` this is accomplished with:
- `opt.SetUnknownMode(getoptions.Pass)`.
=== Fail on unknown
The opposite of the above option.
Useful if you want to ensure there are no input mistakes and force the application to stop.
In `go-getoptions` this is the default behaviour.
It can be explicitly set with:
`opt.SetUnknownMode(getoptions.Fail)`.
=== Warn on unknown
Less strict parsing of options.
This will warn the user that the option used is not a valid option but it will not stop the rest of the program.
In `go-getoptions` this is accomplished with:
- `opt.SetUnknownMode(getoptions.Warn)`.
=== Option aliases
Options should be allowed to have different aliases.
For example, the same option could be invoked with `--address` or `--hostname`.
In `go-getoptions`, pass `opt.Alias("my-alias")` to any option.
For example:
`opt.BoolVar(&flag, "flag", false, opt.Alias("alias", "alias-2"))`
Finally, to know with what alias an option was called with used `opt.CalledAs(<name>)`.
=== Required options
Mark an option as required.
Return an error if the option is not called.
In `go-getoptions`, pass `opt.Required()` to any option.
For example:
`opt.BoolVar(&flag, "flag", false, opt.Required())`
Optionally, override the default error message with `opt.Required(msg)`.
For example:
`opt.BoolVar(&flag, "flag", false, opt.Required("Missing --flag!"))`
=== Incremental option
Some options can be passed more than once to increment an internal counter.
For example:
`command --v --v --v`
Could increase the verbosity level each time the option is passed.
In `go-getoptions` this is accomplished with:
- `ptr := opt.Increment(name, default_value)`.
- `opt.IncrementVar(&ptr, name, default_value)`.
=== Additional types
The option parser could provide converters to additional types.
The disadvantage of providing non basic types is that the option parser grows in size.
Not yet implemented in `go-getoptions`.
=== Options with optional arguments
With regular options, when the argument is not passed (for example: `--level` instead of `--level=debug`) you will get a _Missing argument_ error.
When using options with optional arguments, If the argument is not passed, the option will set the default value for the option type.
For this feature to be fully effective in strong typed languages where types have defaults, there must be a means to query the option parser to determine whether or not the option was called or not.
In `go-getoptions` this is accomplished with:
- `ptr := opt.StringOptional(name, default_value)`.
- `ptr := opt.IntOptional(name, default_value)`.
- `ptr := opt.Float64Optional(name, default_value)`.
- The above should be used in combination with `opt.Called(name)`.
For example, for the following definition:
`ptr := opt.StringOptional("level", "info")`
* If the option `level` is called with just `--level`, the value of `*ptr` is the default `"info"` and querying `opt.Called("level")` returns `true`.
* If the option `level` is called with `--level=debug`, the value of `*ptr` is `"debug"` and querying `opt.Called("level")` returns `true`.
* Finally, If the option `level` is not called, the value of `*ptr` is the default `"info"` and querying `opt.Called("level")` returns `false`.
=== Option flags that call a method internally
If all the flag is doing is call a method or function when present, then having a way to call that function directly saves the programmer some time.
Not yet implemented in `go-getoptions`.
[[operation_modes]]
== Operation Modes
Notice how so far only long options (options starting with double dash `--`) have been mentioned.
There are 3 main ways to handle short options (options starting with only one dash `-`).
The behaviour for long options (options starting with double dash `--`) is consistent across operation modes.
The behaviour for short options (options starting with only one dash `-`) depends on the _operation mode_.
The sections below show the different operation modes.
=== Normal Mode (default)
|===
|Given argument |Interpretation
|--opt
a|option: `"opt"`, argument: `nil`
|--opt=arg
a|option: `"opt"`, argument: `"arg"` footnote:[Argument gets type casted depending on option definition.]
|-opt
a|option: `"opt"`, argument: `nil`
|-opt=arg
a|option: `"opt"`, argument: `"arg"` footnote:[Argument gets type casted depending on option definition.]
|===
=== Bundling Mode
Set by defining `opt.SetMode(getoptions.Bundling)`.
|===
|Given option |Interpretation
|--opt
a|option: `"opt"`, argument: `nil`
|--opt=arg
a|option: `"opt"`, argument: `"arg"` footnote:[Argument gets type casted depending on option definition.]
|-opt
a|option: `"o"`, argument: `nil` +
option: `"p"`, argument: `nil` +
option: `"t"`, argument: `nil`
|-opt=arg
a|option: `"o"`, argument: `nil` +
option: `"p"`, argument: `nil` +
option: `"t"`, argument: `"arg"` footnote:[Argument gets type casted depending on option definition.]
|===
=== Enforce Single Dash Mode
Set by defining `opt.SetMode(getoptions.SingleDash)`.
|===
|Given option |Interpretation
|--opt
a|option: `"opt"`, argument: `nil`
|--opt=arg
a|option: `"opt"`, argument: `"arg"` footnote:[Argument gets type casted depending on option definition.]
|-opt
a|option: `"o"`, argument: `"pt"` footnote:[Argument gets type casted depending on option definition.]
|-opt=arg
a|option: `"o"`, argument: `"pt=arg"` footnote:[Argument gets type casted depending on option definition.]
|===
== Biggest option parser misfeature - Automatically generate help
The biggest misfeature an option parser can have is to automatically generate the help message for the programmer.
This seemingly helpful feature has caused most tools not to have proper man pages anymore and to have all verbose descriptions mixed in the help synopsis.
If you are writing a mid to large tool, don't be lazy, write a man page for your program!
If you are looking for options, link:http://asciidoctor.org/[asciidoctor] has a manpage backend that can generate manpages written in the Asciidoc markup.
For the help synopsis, however, use the automated help.
It even shows when an option can be set with environment variables.
For example, the following is a script using the built in help:
----
$ ./aws-configure -h
NAME:
aws-configure - Generate default ~/.aws/config and ~/.aws/credentials configuration.
When a role is passed, it allows the use of the role in the default profile.
NOTE: Remember to unset AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY after use.
SYNOPSIS:
aws-configure --access-key-id <string> --region <string>
--secret-access-key <string> [--debug] [--help|-?]
[--output-dir <string>] [--role-arn <string>] [--version|-V]
[<args>]
REQUIRED PARAMETERS:
--access-key-id <string> AWS Access Key ID. (env: AWS_ACCESS_KEY_ID)
--region <string> Default Region. (env: AWS_DEFAULT_REGION)
--secret-access-key <string> AWS Secret Access Key. (env: AWS_SECRET_ACCESS_KEY)
OPTIONS:
--debug (default: false)
--help|-? (default: false)
--output-dir <string> Where to place the config and credentials file. (default: "/home/david/.aws")
--role-arn <string> Role ARN. (default: "", env: AWS_ROLE_ARN)
--version|-V (default: false)
----
And below is the output of the automated help of a program with multiple commands:
----
$ menu
SYNOPSIS:
menu [--config <string>] [--debug] [--help|-?] [--profile <string>]
[--region <string>] [--role <string>] [--version|-V] <command> [<args>]
COMMANDS:
docker docker tasks
help Use 'menu help <command>' for extra details.
instance Actions on your deployed instances
terraform Run terraform commands from inside the container
OPTIONS:
--config <string> (default: "config.yml")
--debug (default: false)
--help|-? (default: false)
--profile <string> (default: "default")
--region <string> (default: "us-west-2")
--role <string> (default: "")
--version|-V (default: false)
Use 'menu help <command>' for extra details.
----
== Command behaviour
This section describes how the parser resolves ambiguities between the program and the command.
Given a definition like:
func main() {
var profile, password string
opt := New()
opt.SetUnknownMode(Pass)
opt.StringVar(&profile, "profile", "")
command := NewCommand()
command.StringVar(&password, "password", "")
opt.Command(command.Self("command", "").SetCommandFn(commandFn))
remaining, err := opt.Parse(os.Args[1:])
...
err = opt.Dispatch("help", remaining)
...
}
func commandFn(opt *getoptions.GetOpt, args []string) error {
args, err := opt.Parse(remaining)
...
}
There is an option at the parent, `profile` and one at the command, `password`.
Passing `--p <arg>` is ambiguous and results in an error.
At minimum, `--pr <arg>` and `--pa <arg>` are required.
Given a definition like:
func main() {
var profile, password string
opt := New()
opt.SetUnknownMode(Pass)
opt.StringVar(&profile, "profile", "")
command := NewCommand()
command.StringVar(&password, "password", "", opt.Alias("p"))
opt.Command(command.Self("command", "").SetCommandFn(commandFn))
remaining, err := opt.Parse(os.Args[1:])
...
err = opt.Dispatch("help", remaining)
...
}
func commandFn(opt *getoptions.GetOpt, args []string) error {
args, err := opt.Parse(remaining)
...
}
There is an option at the parent, `profile` and one at the command, `password` with alias `p`.
Passing `--p <arg>` at the parent results in the parent `opt.Parse` call to leave the `--p <arg>` option unhandled and leave it in the remaining slice.
The `opt.Dispatch` call gets the `-p <arg>` option and throws an error.
At minimum, `--pr <arg>` is required to call `profile` at the parent and command options must be passed after the command declaration.
For example, the calls below is correct:
$ ./program -pr <profile> command -p <password>
$ ./program command -pr <profile> -p <password>
But the following one is incorrect:
./program -pr <profile> -p <password> command
== Environment Variables Support
Initial support for environment variables has been added.
Currently, only:
- `opt.Bool` and `opt.BoolVar`
- `opt.String`, `opt.StringVar`, `opt.StringOptional`, and `opt.StringVarOptional`
- `opt.Int`, `opt.IntVar`, `opt.IntOptional`, and `opt.IntVarOptional`
- `opt.Float64`, `opt.Float64Var`, `opt.Float64Optional`, and `opt.Float64VarOptional`
To use it, set the option modify function to opt.GetEnv.
For example:
[source, go]
----
var profile string
opt.StringVar(&profile, "profile", "default", opt.GetEnv("AWS_PROFILE"))
----
Or:
[source, go]
----
profile := opt.String("profile", "default", opt.GetEnv("AWS_PROFILE"))
----
NOTE: Non supported option types behave with a No-Op when `opt.GetEnv` is defined.
When using `opt.GetEnv` with `opt.Bool` or `opt.BoolVar`, only the words "true" or "false" are valid.
They can be provided in any casing, for example: "true", "True" or "TRUE".
NOTE: For numeric values, `opt.Int` and `opt.Float64` and their derivatives, environment variable string conversion errors are ignored and the default value is assigned.
=== Possible Env Variable Roadmap
The Roadmap isn't clear given that there might not be enough value in implementing all of them.
* Handle `opt.Int` and `opt.Float64` errors.
StringSlice and StringSliceVar:: Comma separated? <- Most likely
+
Comma space separated?
Proper CSV parsing to allow comma escaping?
IntSlice and IntSliceVar:: Comma separated?
StringMap and StringMapVar:: Comma separated key=value?
[[roadmap]]
== ROADMAP
* Create new error description for errors when parsing integer ranges (`1..3`).
* Option that runs a function?
* Case insensitive matching.
* Option values in the bundle: `-h1024w800` -> `-h 1024 -w 800`
* prefix and prefix_pattern.
The string that starts options.
Defaults to "--" and "-" but could include "/" to support Win32 style argument handling.
* Supports argument dividers other than '='.
For example: You could define ':' and use `--string=mystring`, `--string:mystring` and `--string mystring`.
* All other Perl's Getopt::Long goodies that seem reasonable to add!
* Remove need for `opt.HelpCommand("")` when dispatch is defined.
+
Currently we have to define the `opt.Bool("help", false)` flag, then `opt.HelpCommand("")`, and finally `opt.Dispatch(ctx, "help", remaining)`.
`opt.HelpCommand` is redundant.
Additionally `opt.HelpCommand` has the `help` command name hardcoded in it.
== License
This file is part of go-getoptions.
Copyright (C) 2015-2020 David Gamba Rios
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.
Documentation
¶
Overview ¶
Package getoptions - Go option parser inspired on the flexibility of Perl’s GetOpt::Long.
It will operate on any given slice of strings and return the remaining (non used) command line arguments. This allows to easily subcommand.
See https://github.com/DavidGamba/go-getoptions for extra documentation details.
Features ¶
• Allow passing options and non-options in any order.
• Support for `--long` options.
• Support for short (`-s`) options with flexible behaviour (see https://github.com/DavidGamba/go-getoptions#operation_modes for details):
- Normal (default)
- Bundling
- SingleDash
• `Called()` method indicates if the option was passed on the command line.
• Multiple aliases for the same option. e.g. `help`, `man`.
• `CalledAs()` method indicates what alias was used to call the option on the command line.
• Simple synopsis and option list automated help.
• Boolean, String, Int and Float64 type options.
• Negatable Boolean options. For example: `--verbose`, `--no-verbose` or `--noverbose`.
• Options with Array arguments. The same option can be used multiple times with different arguments. The list of arguments will be saved into an Array like structure inside the program.
• Options with array arguments and multiple entries. For example: `color --rgb 10 20 30 --next-option`
• When using integer array options with multiple arguments, positive integer ranges are allowed. For example: `1..3` to indicate `1 2 3`.
• Options with key value arguments and multiple entries.
• Options with Key Value arguments. This allows the same option to be used multiple times with arguments of key value type. For example: `rpmbuild --define name=myrpm --define version=123`.
• Supports passing `--` to stop parsing arguments (everything after will be left in the `remaining []string`).
• Supports command line options with '='. For example: You can use `--string=mystring` and `--string mystring`.
• Allows passing arguments to options that start with dash `-` when passed after equal. For example: `--string=--hello` and `--int=-123`.
• Options with optional arguments. If the default argument is not passed the default is set. For example: You can call `--int 123` which yields `123` or `--int` which yields the given default.
• Allows abbreviations when the provided option is not ambiguous. For example: An option called `build` can be called with `--b`, `--bu`, `--bui`, `--buil` and `--build` as long as there is no ambiguity. In the case of ambiguity, the shortest non ambiguous combination is required.
• Support for the lonesome dash "-". To indicate, for example, when to read input from STDIO.
• Incremental options. Allows the same option to be called multiple times to increment a counter.
• Supports case sensitive options. For example, you can use `v` to define `verbose` and `V` to define `Version`.
• Support indicating if an option is required and allows overriding default error message.
• Errors exposed as public variables to allow overriding them for internationalization.
• Supports subcommands (stop parsing arguments when non option is passed).
• Multiple ways of managing unknown options:
- Fail on unknown (default).
- Warn on unknown.
- Pass through, allows for subcommands and can be combined with Require Order.
• Require order: Allows for subcommands. Stop parsing arguments when the first non-option is found. When mixed with Pass through, it also stops parsing arguments when the first unmatched option is found.
Panic ¶
The library will panic if it finds that the programmer (not end user):
• Defined the same alias twice.
• Defined wrong min and max values for SliceMulti methods.
Example ¶
package main
import (
"fmt"
"io/ioutil"
"log"
"os"
"github.com/DavidGamba/go-getoptions"
)
var logger = log.New(ioutil.Discard, "DEBUG: ", log.LstdFlags)
func main() {
// Declare the variables you want your options to update
var debug bool
var greetCount int
var list map[string]string
// Declare the GetOptions object
opt := getoptions.New()
// Options definition
opt.Bool("help", false, opt.Alias("h", "?")) // Aliases can be defined
opt.BoolVar(&debug, "debug", false)
opt.IntVar(&greetCount, "greet", 0,
opt.Required(),
opt.Description("Number of times to greet."), // Set the automated help description
opt.ArgName("number"), // Change the help synopsis arg from the default <int> to <number>
)
opt.StringMapVar(&list, "list", 1, 99,
opt.Description("Greeting list by language."),
opt.ArgName("lang=msg"), // Change the help synopsis arg from <key=value> to <lang=msg>
)
// // Parse cmdline arguments os.Args[1:]
remaining, err := opt.Parse([]string{"-g", "2", "-l", "en='Hello World'", "es='Hola Mundo'"})
// Handle help before handling user errors
if opt.Called("help") {
fmt.Fprintf(os.Stderr, opt.Help())
os.Exit(1)
}
// Handle user errors
if err != nil {
fmt.Fprintf(os.Stderr, "ERROR: %s\n\n", err)
fmt.Fprintf(os.Stderr, opt.Help(getoptions.HelpSynopsis))
os.Exit(1)
}
// Use the passed command line options... Enjoy!
if debug {
logger.SetOutput(os.Stderr)
}
logger.Printf("Unhandled CLI args: %v\n", remaining)
// Use the int variable
for i := 0; i < greetCount; i++ {
fmt.Println("Hello World, from go-getoptions!")
}
// Use the map[string]string variable
if len(list) > 0 {
fmt.Printf("Greeting List:\n")
for k, v := range list {
fmt.Printf("\t%s=%s\n", k, v)
}
}
}
Output: Hello World, from go-getoptions! Hello World, from go-getoptions! Greeting List: en='Hello World' es='Hola Mundo'
Index ¶
- Variables
- type CommandFn
- type GetOpt
- func (gopt *GetOpt) Alias(alias ...string) ModifyFn
- func (gopt *GetOpt) ArgName(name string) ModifyFn
- func (gopt *GetOpt) Bool(name string, def bool, fns ...ModifyFn) *bool
- func (gopt *GetOpt) BoolVar(p *bool, name string, def bool, fns ...ModifyFn)
- func (gopt *GetOpt) Called(name string) bool
- func (gopt *GetOpt) CalledAs(name string) string
- func (gopt *GetOpt) CustomCompletion(list []string) *GetOpt
- func (gopt *GetOpt) Description(msg string) ModifyFn
- func (gopt *GetOpt) Dispatch(ctx context.Context, helpCommandName string, args []string) error
- func (gopt *GetOpt) Float64(name string, def float64, fns ...ModifyFn) *float64
- func (gopt *GetOpt) Float64Optional(name string, def float64, fns ...ModifyFn) *float64
- func (gopt *GetOpt) Float64Var(p *float64, name string, def float64, fns ...ModifyFn)
- func (gopt *GetOpt) Float64VarOptional(p *float64, name string, def float64, fns ...ModifyFn)
- func (gopt *GetOpt) GetEnv(name string) ModifyFn
- func (gopt *GetOpt) Help(sections ...HelpSection) string
- func (gopt *GetOpt) HelpCommand(description string) *GetOpt
- func (gopt *GetOpt) HelpSynopsisArgs(args string) *GetOpt
- func (gopt *GetOpt) Increment(name string, def int, fns ...ModifyFn) *int
- func (gopt *GetOpt) IncrementVar(p *int, name string, def int, fns ...ModifyFn)
- func (gopt *GetOpt) Int(name string, def int, fns ...ModifyFn) *int
- func (gopt *GetOpt) IntOptional(name string, def int, fns ...ModifyFn) *int
- func (gopt *GetOpt) IntSlice(name string, min, max int, fns ...ModifyFn) *[]int
- func (gopt *GetOpt) IntSliceVar(p *[]int, name string, min, max int, fns ...ModifyFn)
- func (gopt *GetOpt) IntVar(p *int, name string, def int, fns ...ModifyFn)
- func (gopt *GetOpt) IntVarOptional(p *int, name string, def int, fns ...ModifyFn)
- func (gopt *GetOpt) InterruptContext() (ctx context.Context, cancel context.CancelFunc, done chan struct{})
- func (gopt *GetOpt) NewCommand(name string, description string) *GetOpt
- func (gopt *GetOpt) Option(name string) *option.Option
- func (gopt *GetOpt) Parse(args []string) ([]string, error)
- func (gopt *GetOpt) Required(msg ...string) ModifyFn
- func (gopt *GetOpt) Self(name string, description string) *GetOpt
- func (gopt *GetOpt) SetCommandFn(fn CommandFn) *GetOpt
- func (gopt *GetOpt) SetMapKeysToLower() *GetOpt
- func (gopt *GetOpt) SetMode(mode Mode) *GetOpt
- func (gopt *GetOpt) SetRequireOrder() *GetOpt
- func (gopt *GetOpt) SetUnknownMode(mode UnknownMode) *GetOpt
- func (gopt *GetOpt) String(name, def string, fns ...ModifyFn) *string
- func (gopt *GetOpt) StringMap(name string, min, max int, fns ...ModifyFn) map[string]string
- func (gopt *GetOpt) StringMapVar(m *map[string]string, name string, min, max int, fns ...ModifyFn)
- func (gopt *GetOpt) StringOptional(name string, def string, fns ...ModifyFn) *string
- func (gopt *GetOpt) StringSlice(name string, min, max int, fns ...ModifyFn) *[]string
- func (gopt *GetOpt) StringSliceVar(p *[]string, name string, min, max int, fns ...ModifyFn)
- func (gopt *GetOpt) StringVar(p *string, name, def string, fns ...ModifyFn)
- func (gopt *GetOpt) StringVarOptional(p *string, name, def string, fns ...ModifyFn)
- func (gopt *GetOpt) Stringer() string
- func (gopt *GetOpt) Value(name string) interface{}
- type HelpSection
- type Mode
- type ModifyFn
- type UnknownMode
Examples ¶
Constants ¶
This section is empty.
Variables ¶
Debug Logger instance set to `ioutil.Discard` by default. Enable debug logging by setting: `Debug.SetOutput(os.Stderr)`.
var ErrorHelpCalled = fmt.Errorf("help called")
ErrorHelpCalled - Indicates the help has been handled.
Functions ¶
This section is empty.
Types ¶
type GetOpt ¶
type GetOpt struct {
// CommandFn
CommandFn CommandFn
// Debugging
Writer io.Writer // io.Writer to write warnings to. Defaults to os.Stderr.
// contains filtered or unexported fields
}
GetOpt - main object.
func New ¶
func New() *GetOpt
New returns an empty object of type GetOpt. This is the starting point when using go-getoptions. For example:
opt := getoptions.New()
func (*GetOpt) Alias ¶ added in v0.12.0
Alias - Adds aliases to an option.
Example ¶
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("?"))
_, _ = opt.Parse([]string{"-?"})
if opt.Called("help") {
fmt.Println("help called")
}
if opt.CalledAs("help") == "?" {
fmt.Println("help called as ?")
}
Output: help called help called as ?
func (*GetOpt) ArgName ¶ added in v0.13.0
ArgName - Add an argument name to an option for use in automated help. For example, by default a string option will have a default synopsis as follows:
--host <string>
If ArgName("hostname") is used, the synopsis will read:
--host <hostname>
Example ¶
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("?"))
opt.String("host-default", "")
opt.String("host-custom", "", opt.ArgName("hostname"))
_, _ = opt.Parse([]string{"-?"})
if opt.Called("help") {
fmt.Println(opt.Help())
}
Output: SYNOPSIS: go-getoptions.test [--help|-?] [--host-custom <hostname>] [--host-default <string>] [<args>] OPTIONS: --help|-? (default: false) --host-custom <hostname> (default: "") --host-default <string> (default: "")
func (*GetOpt) Bool ¶
Bool - define a `bool` option and its aliases. It returns a `*bool` pointing to the variable holding the result. If the option is found, the result will be the opposite of the provided default.
Example ¶
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("?"))
_, _ = opt.Parse([]string{"-?"})
if opt.Called("help") {
fmt.Println(opt.Help())
}
Output: SYNOPSIS: go-getoptions.test [--help|-?] [<args>] OPTIONS: --help|-? (default: false)
func (*GetOpt) BoolVar ¶
BoolVar - define a `bool` option and its aliases. The result will be available through the variable marked by the given pointer. If the option is found, the result will be the opposite of the provided default.
Example ¶
var help bool
opt := getoptions.New()
opt.BoolVar(&help, "help", false, opt.Alias("?"))
_, _ = opt.Parse([]string{"-?"})
if help {
fmt.Println(opt.Help())
}
Output: SYNOPSIS: go-getoptions.test [--help|-?] [<args>] OPTIONS: --help|-? (default: false)
func (*GetOpt) Called ¶
Called - Indicates if the option was passed on the command line. If the `name` is an option that wasn't declared it will return false.
Example ¶
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("?"))
_, _ = opt.Parse([]string{"-?"})
if opt.Called("help") {
fmt.Println("help called")
}
if opt.CalledAs("help") == "?" {
fmt.Println("help called as ?")
}
Output: help called help called as ?
func (*GetOpt) CalledAs ¶ added in v0.13.0
CalledAs - Returns the alias used to call the option. Empty string otherwise.
If the `name` is an option that wasn't declared it will return an empty string.
For options that can be called multiple times, the last alias used is returned.
Example ¶
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("?"))
_, _ = opt.Parse([]string{"-?"})
if opt.Called("help") {
fmt.Println("help called")
}
if opt.CalledAs("help") == "?" {
fmt.Println("help called as ?")
}
Output: help called help called as ?
func (*GetOpt) CustomCompletion ¶ added in v0.14.0
CustomCompletion - Add a custom completion list.
func (*GetOpt) Description ¶ added in v0.13.0
Description - Add a description to an option for use in automated help.
Example ¶
opt := getoptions.New()
opt.HelpSynopsisArgs("[<commands>]")
opt.Bool("help", false, opt.Alias("?"), opt.Description("Show help."))
opt.String("hostname", "golang.org", opt.ArgName("host|IP"), opt.Description("Hostname to use."))
opt.String("user", "", opt.ArgName("user_id"), opt.Required(), opt.Description("User to login as."))
_, _ = opt.Parse([]string{"-?"})
if opt.Called("help") {
fmt.Println(opt.Help())
}
Output: SYNOPSIS: go-getoptions.test --user <user_id> [--help|-?] [--hostname <host|IP>] [<commands>] REQUIRED PARAMETERS: --user <user_id> User to login as. OPTIONS: --help|-? Show help. (default: false) --hostname <host|IP> Hostname to use. (default: "golang.org")
func (*GetOpt) Dispatch ¶ added in v0.15.0
Dispatch - Call CommandFn for the program commands based on the contents of the args slice. By default, if given the helpCommandName (normally just "help") as the first argument, it will print the help for the parent. If given helpCommandName plus the name of the command, it will print the help for the command.
Example ¶
package main
import (
"context"
"errors"
"fmt"
"io/ioutil"
"log"
"os"
"github.com/DavidGamba/go-getoptions"
)
var dispatchLogger = log.New(ioutil.Discard, "DEBUG: ", log.LstdFlags)
func listRun(ctx context.Context, opt *getoptions.GetOpt, args []string) error {
fmt.Println("a, b, c, d")
return nil
}
func main() {
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("?"))
opt.Bool("debug", false)
opt.SetRequireOrder()
opt.SetUnknownMode(getoptions.Pass)
list := opt.NewCommand("list", "list stuff").SetCommandFn(listRun)
list.Bool("list-opt", false)
opt.HelpCommand("")
remaining, err := opt.Parse([]string{"list"}) // <- argv set to call command
if err != nil {
fmt.Fprintf(os.Stderr, "ERROR: %s\n", err)
os.Exit(1)
}
opt.Writer = os.Stdout // Print help to stdout instead of stderr for test purpose
err = opt.Dispatch(context.Background(), "help", remaining)
if err != nil {
if errors.Is(err, getoptions.ErrorHelpCalled) {
os.Exit(1)
}
fmt.Fprintf(os.Stderr, "ERROR: %s\n", err)
os.Exit(1)
}
}
Output: a, b, c, d
Example (BHelp) ¶
package main
import (
"context"
"errors"
"fmt"
"io/ioutil"
"log"
"os"
"github.com/DavidGamba/go-getoptions"
)
var dispatchHelpLogger = log.New(ioutil.Discard, "DEBUG: ", log.LstdFlags)
func dispatchHelpListRun(ctx context.Context, opt *getoptions.GetOpt, args []string) error {
return nil
}
func main() {
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("?"))
opt.Bool("debug", false)
opt.SetRequireOrder()
opt.SetUnknownMode(getoptions.Pass)
list := opt.NewCommand("list", "list stuff")
list.SetCommandFn(dispatchHelpListRun)
list.Bool("list-opt", false)
opt.HelpCommand("")
remaining, err := opt.Parse([]string{"help"}) // <- argv set to call help
if err != nil {
fmt.Fprintf(os.Stderr, "ERROR: %s\n", err)
os.Exit(1)
}
opt.Writer = os.Stdout // Print help to stdout instead of stderr for test purpose
err = opt.Dispatch(context.Background(), "help", remaining)
if err != nil {
if errors.Is(err, getoptions.ErrorHelpCalled) {
os.Exit(1)
}
fmt.Fprintf(os.Stderr, "ERROR: %s\n", err)
os.Exit(1)
}
}
Output: SYNOPSIS: go-getoptions.test [--debug] [--help|-?] <command> [<args>] COMMANDS: help Use 'go-getoptions.test help <command>' for extra details. list list stuff OPTIONS: --debug (default: false) --help|-? (default: false) Use 'go-getoptions.test help <command>' for extra details.
Example (CCommandHelp) ¶
package main
import (
"context"
"errors"
"fmt"
"io/ioutil"
"log"
"os"
"github.com/DavidGamba/go-getoptions"
)
var dispatchCommandHelpLogger = log.New(ioutil.Discard, "DEBUG: ", log.LstdFlags)
func dispatchCommandHelpListRun(ctx context.Context, opt *getoptions.GetOpt, args []string) error {
return nil
}
func main() {
opt := getoptions.New()
opt.Bool("help", false, opt.Alias("?"))
opt.Bool("debug", false)
opt.SetRequireOrder()
opt.SetUnknownMode(getoptions.Pass)
list := opt.NewCommand("list", "list stuff")
list.SetCommandFn(dispatchCommandHelpListRun)
list.Bool("list-opt", false)
opt.HelpCommand("")
remaining, err := opt.Parse([]string{"help", "list"}) // <- argv set to call command help
if err != nil {
fmt.Fprintf(os.Stderr, "ERROR: %s\n", err)
os.Exit(1)
}
opt.Writer = os.Stdout // Print help to stdout instead of stderr for test purpose
err = opt.Dispatch(context.Background(), "help", remaining)
if err != nil {
if errors.Is(err, getoptions.ErrorHelpCalled) {
os.Exit(1)
}
fmt.Fprintf(os.Stderr, "ERROR: %s\n", err)
os.Exit(1)
}
}
Output: NAME: go-getoptions.test list - list stuff SYNOPSIS: go-getoptions.test list [--debug] [--help|-?] [--list-opt] [<args>] OPTIONS: --debug (default: false) --help|-? (default: false) --list-opt (default: false)
func (*GetOpt) Float64Optional ¶ added in v0.23.0
Float64Optional - define an `float64` option and its aliases.
func (*GetOpt) Float64Var ¶
Float64Var - define an `float64` option and its aliases. The result will be available through the variable marked by the given pointer.
func (*GetOpt) Float64VarOptional ¶ added in v0.23.0
Float64VarOptional - define an `float64` option and its aliases. The result will be available through the variable marked by the given pointer.
func (*GetOpt) GetEnv ¶ added in v0.18.0
GetEnv - Will read an environment variable if set. Precedence higher to lower: CLI option, environment variable, option default.
Currently, only `opt.Bool`, `opt.BoolVar`, `opt.String`, and `opt.StringVar` are supported.
When an environment variable that matches the variable from opt.GetEnv is set, opt.GetEnv will set opt.Called(name) to true and will set opt.CalledAs(name) to the name of the environment variable used. In other words, when an option is required (opt.Required is set) opt.GetEnv satisfies that requirement.
When using `opt.GetEnv` with `opt.Bool` or `opt.BoolVar`, only the words "true" or "false" are valid. They can be provided in any casing, for example: "true", "True" or "TRUE".
NOTE: Non supported option types behave with a No-Op when `opt.GetEnv` is defined.
Example ¶
os.Setenv("_AWS_PROFILE", "production")
var profile string
opt := getoptions.New()
opt.StringVar(&profile, "profile", "default", opt.GetEnv("_AWS_PROFILE"))
_, _ = opt.Parse([]string{})
fmt.Println(profile)
os.Unsetenv("_AWS_PROFILE")
Output: production
func (*GetOpt) Help ¶ added in v0.13.0
func (gopt *GetOpt) Help(sections ...HelpSection) string
Help - Default help string that is composed of the HelpSynopsis and HelpOptionList.
func (*GetOpt) HelpCommand ¶ added in v0.15.0
HelpCommand - Adds a help command with completion for all other commands.
NOTE: Define after all other commands have been defined.
func (*GetOpt) HelpSynopsisArgs ¶ added in v0.16.0
HelpSynopsisArgs - Defines the help synopsis args description. Defaults to: [<args>]
func (*GetOpt) Increment ¶
Increment - When called multiple times it increments the int counter defined by this option.
func (*GetOpt) IncrementVar ¶
IncrementVar - When called multiple times it increments the provided int.
func (*GetOpt) IntOptional ¶
IntOptional - define a `int` option and its aliases.
IntOptional will set the int to the provided default value when no value is given. For example, when called with `--intOpt 123`, the value is `123`. when called with `--intOpt` the value is the given default.
func (*GetOpt) IntSlice ¶ added in v0.11.0
IntSlice - define a `[]int` option and its aliases.
IntSlice will accept multiple calls to the same option and append them to the `[]int`. For example, when called with `--intRpt 1 --intRpt 2`, the value is `[]int{1, 2}`.
Additionally, IntSlice will allow to define a min and max amount of arguments to be passed at once. For example, when min is 1 and max is 3 and called with `--strRpt 1 2 3`, the value is `[]int{1, 2, 3}`. It could also be called with `--strRpt 1 --strRpt 2 --strRpt 3` for the same result.
When min is bigger than 1, it is required to pass the amount of arguments defined by min at once. For example: with `min = 2`, you at least require `--strRpt 1 2 --strRpt 3`
Finally, positive integer ranges are allowed. For example, Instead of writing: `csv --columns 1 2 3` or `csv --columns 1 --columns 2 --columns 3` The input could be: `csv --columns 1..3`.
func (*GetOpt) IntSliceVar ¶ added in v0.11.0
IntSliceVar - define a `[]int` option and its aliases.
IntSliceVar will accept multiple calls to the same option and append them to the `[]int`. For example, when called with `--intRpt 1 --intRpt 2`, the value is `[]int{1, 2}`.
Additionally, IntSliceVar will allow to define a min and max amount of arguments to be passed at once. For example, when min is 1 and max is 3 and called with `--strRpt 1 2 3`, the value is `[]int{1, 2, 3}`. It could also be called with `--strRpt 1 --strRpt 2 --strRpt 3` for the same result.
When min is bigger than 1, it is required to pass the amount of arguments defined by min at once. For example: with `min = 2`, you at least require `--strRpt 1 2 --strRpt 3`
Finally, positive integer ranges are allowed. For example, Instead of writing: `csv --columns 1 2 3` or `csv --columns 1 --columns 2 --columns 3` The input could be: `csv --columns 1..3`.
func (*GetOpt) IntVar ¶
IntVar - define an `int` option and its aliases. The result will be available through the variable marked by the given pointer.
func (*GetOpt) IntVarOptional ¶
IntVarOptional - define a `int` option and its aliases. The result will be available through the variable marked by the given pointer.
IntOptional will set the int to the provided default value when no value is given. For example, when called with `--intOpt 123`, the value is `123`. when called with `--intOpt` the value is the given default.
func (*GetOpt) InterruptContext ¶ added in v0.17.0
func (gopt *GetOpt) InterruptContext() (ctx context.Context, cancel context.CancelFunc, done chan struct{})
InterruptContext - Creates a top level context that listens to os.Interrupt, syscall.SIGHUP and syscall.SIGTERM and calls the CancelFunc if the signals are triggered. When the listener finishes its work, it sends a message to the done channel.
Use:
func main() { ...
ctx, cancel, done := getoptions.InterruptContext()
defer func() { cancel(); <-done }()
NOTE: InterruptContext is a method to reuse gopt.Writer
func (*GetOpt) NewCommand ¶ added in v0.17.0
NewCommand - Returns a new GetOpt object representing a new command.
func (*GetOpt) Parse ¶
Parse - Call the parse method when done describing. It will operate on any given slice of strings and return the remaining (non used) command line arguments. This allows to easily subcommand.
Parsing style is controlled by the `Set` methods (SetMode, SetRequireOrder, etc).
// Declare the GetOptions object opt := getoptions.New() ... // Parse cmdline arguments or any provided []string remaining, err := opt.Parse(os.Args[1:])
func (*GetOpt) Required ¶ added in v0.12.0
Required - Automatically return an error if the option is not called. Optionally provide an error message if the option is not called. A default error message will be used otherwise.
func (*GetOpt) Self ¶ added in v0.14.0
Self - Set a custom name and description that will show in the automated help. If name is an empty string, it will only use the description and use the name as the executable name.
func (*GetOpt) SetCommandFn ¶ added in v0.15.0
SetCommandFn - Defines the command entry point function.
func (*GetOpt) SetMapKeysToLower ¶ added in v0.11.0
SetMapKeysToLower - StringMap keys captured from StringMap are lower case. For example:
command --opt key=value
And:
command --opt KEY=value
Would both return `map[string]string{"key":"value"}`.
func (*GetOpt) SetMode ¶
SetMode - Sets the Operation Mode. The operation mode only affects options starting with a single dash '-'. The available operation modes are: normal, bundling or singleDash.
The following table shows the different operation modes given the string "-opt=arg".
.Operation Modes for string "-opt=arg"
|===
|Mode |Description
|normal |option: opt
argument: arg
|bundling |option: o
argument: nil
option: p
argument: nil
option: t
argument: arg
|singleDash |option: o
argument: pt=arg
|===
See https://github.com/DavidGamba/go-getoptions#operation_modes for more details.
func (*GetOpt) SetRequireOrder ¶
SetRequireOrder - Stop parsing options when a subcommand is passed. Put every remaining argument, including the subcommand, in the `remaining` slice.
A subcommand is assumed to be the first argument that is not an option or an argument to an option. When a subcommand is found, stop parsing arguments and let a subcommand handler handle the remaining arguments. For example:
command --opt arg subcommand --subopt subarg
In the example above, `--opt` is an option and `arg` is an argument to an option, making `subcommand` the first non option argument.
This method is useful when both the command and the subcommand have option handlers for the same option.
For example, with:
command --help
`--help` is handled by `command`, and with:
command subcommand --help
`--help` is not handled by `command` since there was a subcommand that caused the parsing to stop. In this case, the `remaining` slice will contain `['subcommand', '--help']` and that can be passed directly to a subcommand's option parser.
func (*GetOpt) SetUnknownMode ¶
func (gopt *GetOpt) SetUnknownMode(mode UnknownMode) *GetOpt
SetUnknownMode - Determines how to behave when encountering an unknown option.
• 'fail' (default) will make 'Parse' return an error with the unknown option information.
• 'warn' will make 'Parse' print a user warning indicating there was an unknown option. The unknown option will be left in the remaining array.
• 'pass' will make 'Parse' ignore any unknown options and they will be passed onto the 'remaining' slice. This allows for subcommands. TODO: Add aliases
func (*GetOpt) String ¶
String - define a `string` option and its aliases. If not called, the return value will be that of the given default `def`.
func (*GetOpt) StringMap ¶
StringMap - define a `map[string]string` option and its aliases.
StringMap will accept multiple calls of `key=value` type to the same option and add them to the `map[string]string` result. For example, when called with `--strMap k=v --strMap k2=v2`, the value is `map[string]string{"k":"v", "k2": "v2"}`.
Additionally, StringMap will allow to define a min and max amount of arguments to be passed at once. For example, when min is 1 and max is 3 and called with `--strMap k=v k2=v2 k3=v3`, the value is `map[string]string{"k":"v", "k2": "v2", "k3": "v3"}`. It could also be called with `--strMap k=v --strMap k2=v2 --strMap k3=v3` for the same result.
When min is bigger than 1, it is required to pass the amount of arguments defined by min at once. For example: with `min = 2`, you at least require `--strMap k=v k2=v2 --strMap k3=v3`
func (*GetOpt) StringMapVar ¶ added in v0.14.0
StringMapVar - define a `map[string]string` option and its aliases.
StringMapVar will accept multiple calls of `key=value` type to the same option and add them to the `map[string]string` result. For example, when called with `--strMap k=v --strMap k2=v2`, the value is `map[string]string{"k":"v", "k2": "v2"}`.
Additionally, StringMapVar will allow to define a min and max amount of arguments to be passed at once. For example, when min is 1 and max is 3 and called with `--strMap k=v k2=v2 k3=v3`, the value is `map[string]string{"k":"v", "k2": "v2", "k3": "v3"}`. It could also be called with `--strMap k=v --strMap k2=v2 --strMap k3=v3` for the same result.
When min is bigger than 1, it is required to pass the amount of arguments defined by min at once. For example: with `min = 2`, you at least require `--strMap k=v k2=v2 --strMap k3=v3`
func (*GetOpt) StringOptional ¶
StringOptional - define a `string` option and its aliases.
StringOptional will set the string to the provided default value when no value is given. For example, when called with `--strOpt value`, the value is `value`. when called with `--strOpt` the value is the given default.
func (*GetOpt) StringSlice ¶
StringSlice - define a `[]string` option and its aliases.
StringSlice will accept multiple calls to the same option and append them to the `[]string`. For example, when called with `--strRpt 1 --strRpt 2`, the value is `[]string{"1", "2"}`.
Additionally, StringSlice will allow to define a min and max amount of arguments to be passed at once. For example, when min is 1 and max is 3 and called with `--strRpt 1 2 3`, the value is `[]string{"1", "2", "3"}`. It could also be called with `--strRpt 1 --strRpt 2 --strRpt 3` for the same result.
When min is bigger than 1, it is required to pass the amount of arguments defined by min at once. For example: with `min = 2`, you at least require `--strRpt 1 2 --strRpt 3`
func (*GetOpt) StringSliceVar ¶ added in v0.11.0
StringSliceVar - define a `[]string` option and its aliases.
StringSliceVar will accept multiple calls to the same option and append them to the `[]string`. For example, when called with `--strRpt 1 --strRpt 2`, the value is `[]string{"1", "2"}`.
Additionally, StringSliceVar will allow to define a min and max amount of arguments to be passed at once. For example, when min is 1 and max is 3 and called with `--strRpt 1 2 3`, the value is `[]string{"1", "2", "3"}`. It could also be called with `--strRpt 1 --strRpt 2 --strRpt 3` for the same result.
When min is bigger than 1, it is required to pass the amount of arguments defined by min at once. For example: with `min = 2`, you at least require `--strRpt 1 2 --strRpt 3`
func (*GetOpt) StringVar ¶
StringVar - define a `string` option and its aliases. The result will be available through the variable marked by the given pointer. If not called, the return value will be that of the given default `def`.
func (*GetOpt) StringVarOptional ¶
StringVarOptional - define a `string` option and its aliases. The result will be available through the variable marked by the given pointer.
StringVarOptional will set the string to the provided default value when no value is given. For example, when called with `--strOpt value`, the value is `value`. when called with `--strOpt` the value is the given default.
type HelpSection ¶ added in v0.14.0
type HelpSection int
HelpSection - Indicates what portion of the help to return.
const ( HelpName HelpSection HelpSynopsis HelpCommandList HelpOptionList )
Help Output Types
type UnknownMode ¶ added in v0.14.0
type UnknownMode int
UnknownMode - Unknown option mode
const ( Fail UnknownMode = iota Warn Pass )
Unknown option modes
Source Files
Directories
¶
| Path | Synopsis |
|---|---|
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Package completion - provides a Tree structure that can be used to define a program's completions.
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Package completion - provides a Tree structure that can be used to define a program's completions. |
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Package dag - Lightweight Directed Acyclic Graph (DAG) Build System.
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Package dag - Lightweight Directed Acyclic Graph (DAG) Build System. |
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examples
|
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Package help - internal help handling code.
|
Package help - internal help handling code. |
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Package option - internal option struct and methods.
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Package option - internal option struct and methods. |
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Package text - User facing strings.
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Package text - User facing strings. |