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Published: Nov 2, 2020 License: MIT, BSD-3-Clause Imports: 17 Imported by: 0



The present file format

Present files have the following format. The first non-blank non-comment line is the title, so the header looks like

Title of document
Subtitle of document
15:04 2 Jan 2006
Tags: foo, bar, baz
<blank line>
Author Name
Job title, Company

The subtitle, date, and tags lines are optional.

The date line may be written without a time:

2 Jan 2006

In this case, the time will be interpreted as 10am UTC on that date.

The tags line is a comma-separated list of tags that may be used to categorize the document.

The author section may contain a mixture of text, twitter names, and links. For slide presentations, only the plain text lines will be displayed on the first slide.

Multiple presenters may be specified, separated by a blank line.

After that come slides/sections, each after a blank line:

  • Title of slide or section (must have asterisk)

    Some Text

    ** Subsection

  • bullets

  • more bullets

  • a bullet with

    *** Sub-subsection

    Some More text

    Preformatted text is indented (however you like)

    Further Text, including invocations like:

    .code x.go /^func main/,/^}/ .play y.go .image image.jpg .iframe http://foo .link http://foo label .html file.html .caption _Gopher_ by [[][Renée French]]

    Again, more text

Blank lines are OK (not mandatory) after the title and after the text. Text, bullets, and .code etc. are all optional; title is not.

Lines starting with # in column 1 are commentary.


Within the input for plain text or lists, text bracketed by font markers will be presented in italic, bold, or program font. Marker characters are _ (italic), * (bold) and ` (program font). Unmatched markers appear as plain text. Within marked text, a single marker character becomes a space and a doubled single marker quotes the marker character.

_Why_use_scoped__ptr_? Use plain ***ptr* instead.

Inline links:

Links can be included in any text with the form [url[label]], or [url] to use the URL itself as the label.


A number of template functions are available through invocations in the input text. Each such invocation contains a period as the first character on the line, followed immediately by the name of the function, followed by any arguments. A typical invocation might be

.play demo.go /^func show/,/^}/

(except that the ".play" must be at the beginning of the line and not be indented like this.)

Here follows a description of the functions:


Injects program source into the output by extracting code from files and injecting them as HTML-escaped <pre> blocks. The argument is a file name followed by an optional address that specifies what section of the file to display. The address syntax is similar in its simplest form to that of ed, but comes from sam and is more general. See Table II

for full details. The displayed block is always rounded out to a full line at both ends.

If no pattern is present, the entire file is displayed.

Any line in the program that ends with the four characters


is deleted from the source before inclusion, making it easy to write things like

.code test.go /START OMIT/,/END OMIT/

to find snippets like this

tedious_code = boring_function()
interesting_code = fascinating_function()

and see only this:

interesting_code = fascinating_function()

Also, inside the displayed text a line that ends

// HL

will be highlighted in the display; the 'h' key in the browser will toggle extra emphasis of any highlighted lines. A highlighting mark may have a suffix word, such as

// HLxxx

Such highlights are enabled only if the code invocation ends with "HL" followed by the word:

.code test.go /^type Foo/,/^}/ HLxxx

The .code function may take one or more flags immediately preceding the filename. This command shows test.go in an editable text area:

.code -edit test.go

This command shows test.go with line numbers:

.code -numbers test.go


The function "play" is the same as "code" but puts a button on the displayed source so the program can be run from the browser. Although only the selected text is shown, all the source is included in the HTML output so it can be presented to the compiler.


Create a hyperlink. The syntax is 1 or 2 space-separated arguments. The first argument is always the HTTP URL. If there is a second argument, it is the text label to display for this link.



The template uses the function "image" to inject picture files.

The syntax is simple: 1 or 3 space-separated arguments. The first argument is always the file name. If there are more arguments, they are the height and width; both must be present, or substituted with an underscore. Replacing a dimension argument with the underscore parameter preserves the aspect ratio of the image when scaling.

.image images/betsy.jpg 100 200

.image images/janet.jpg _ 300


The template uses the function "caption" to inject figure captions.

The text after ".caption" is embedded in a figcaption element after processing styling and links as in standard text lines.

.caption _Gopher_ by [[][Renée French]]


The function "iframe" injects iframes (pages inside pages). Its syntax is the same as that of image.


The function html includes the contents of the specified file as unescaped HTML. This is useful for including custom HTML elements that cannot be created using only the slide format. It is your responsibilty to make sure the included HTML is valid and safe.

.html file.html




This section is empty.


View Source
var PlayEnabled = false

Is the playground available?


func Register

func Register(name string, parser ParseFunc)

Register binds the named action, which does not begin with a period, to the specified parser to be invoked when the name, with a period, appears in the present input text.

func Style

func Style(s string) template.HTML

Style returns s with HTML entities escaped and font indicators turned into HTML font tags.

const s = "*Gophers* are _clearly_ > *cats*!"

<b>Gophers</b> are <i>clearly</i> &gt; <b>cats</b>!

func Template

func Template() *template.Template

Template returns an empty template with the action functions in its FuncMap.


type Author

type Author struct {
	Elem []Elem

Author represents the person who wrote and/or is presenting the document.

func (*Author) TextElem

func (p *Author) TextElem() (elems []Elem)

TextElem returns the first text elements of the author details. This is used to display the author' name, job title, and company without the contact details.

type Caption

type Caption struct {
	Text string

func (Caption) TemplateName

func (c Caption) TemplateName() string

type Code

type Code struct {
	Text     template.HTML
	Play     bool   // runnable code
	FileName string // file name
	Ext      string // file extension
	Raw      []byte // content of the file

func (Code) TemplateName

func (c Code) TemplateName() string

type Context

type Context struct {
	// ReadFile reads the file named by filename and returns the contents.
	ReadFile func(filename string) ([]byte, error)

A Context specifies the supporting context for parsing a presentation.

func (*Context) Parse

func (ctx *Context) Parse(r io.Reader, name string, mode ParseMode) (*Doc, error)

Parse parses a document from r.

type Doc

type Doc struct {
	Title    string
	Subtitle string
	Time     time.Time
	Authors  []Author
	Sections []Section
	Tags     []string

Doc represents an entire document.

func Parse

func Parse(r io.Reader, name string, mode ParseMode) (*Doc, error)

Parse parses a document from r. Parse reads assets used by the presentation from the file system using ioutil.ReadFile.

func (*Doc) Render

func (d *Doc) Render(w io.Writer, t *template.Template) error

Render renders the doc to the given writer using the provided template.

type Elem

type Elem interface {
	TemplateName() string

Elem defines the interface for a present element. That is, something that can provide the name of the template used to render the element.

type HTML

type HTML struct {

func (HTML) TemplateName

func (s HTML) TemplateName() string

type Iframe

type Iframe struct {
	URL    string
	Width  int
	Height int

func (Iframe) TemplateName

func (i Iframe) TemplateName() string

type Image

type Image struct {
	URL    string
	Width  int
	Height int

func (Image) TemplateName

func (i Image) TemplateName() string

type Lines

type Lines struct {
	// contains filtered or unexported fields

Lines is a helper for parsing line-based input.

type Link struct {
	URL   *url.URL
	Label string

func (Link) TemplateName

func (l Link) TemplateName() string

type List

type List struct {
	Bullet []string

List represents a bulleted list.

func (List) TemplateName

func (l List) TemplateName() string

type ParseFunc

type ParseFunc func(ctx *Context, fileName string, lineNumber int, inputLine string) (Elem, error)

type ParseMode

type ParseMode int

ParseMode represents flags for the Parse function.

const (
	// If set, parse only the title and subtitle.
	TitlesOnly ParseMode = 1

type Section

type Section struct {
	Number []int
	Title  string
	Elem   []Elem

Section represents a section of a document (such as a presentation slide) comprising a title and a list of elements.

func (Section) FormattedNumber

func (s Section) FormattedNumber() string

FormattedNumber returns a string containing the concatenation of the numbers identifying a Section.

func (Section) Level

func (s Section) Level() int

Level returns the level of the given section. The document title is level 1, main section 2, etc.

func (*Section) Render

func (s *Section) Render(w io.Writer, t *template.Template) error

Render renders the section to the given writer using the provided template.

func (Section) Sections

func (s Section) Sections() (sections []Section)

func (Section) TemplateName

func (s Section) TemplateName() string

type Text

type Text struct {
	Lines []string
	Pre   bool

Text represents an optionally preformatted paragraph.

func (Text) TemplateName

func (t Text) TemplateName() string

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