Version: v1.8.8 Latest Latest

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Published: May 14, 2018 License: GPL-3.0 Imports: 14 Imported by: 0



Package abi implements the Ethereum ABI (Application Binary Interface).

The Ethereum ABI is strongly typed, known at compile time and static. This ABI will handle basic type casting; unsigned to signed and visa versa. It does not handle slice casting such as unsigned slice to signed slice. Bit size type casting is also handled. ints with a bit size of 32 will be properly cast to int256, etc.




View Source
const (
	IntTy byte = iota

Type enumerator


This section is empty.


func U256

func U256(n *big.Int) []byte

U256 converts a big Int into a 256bit EVM number.


type ABI

type ABI struct {
	Constructor Method
	Methods     map[string]Method
	Events      map[string]Event

The ABI holds information about a contract's context and available invokable methods. It will allow you to type check function calls and packs data accordingly.

func JSON

func JSON(reader io.Reader) (ABI, error)

JSON returns a parsed ABI interface and error if it failed.

const definition = `[{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"isBar","outputs":[{"name":"","type":"bool"}],"type":"function"}]`

abi, err := JSON(strings.NewReader(definition))
if err != nil {
out, err := abi.Pack("isBar", common.HexToAddress("01"))
if err != nil {

fmt.Printf("%x\n", out)


func (*ABI) MethodById added in v1.8.0

func (abi *ABI) MethodById(sigdata []byte) (*Method, error)

MethodById looks up a method by the 4-byte id returns nil if none found

func (ABI) Pack

func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error)

Pack the given method name to conform the ABI. Method call's data will consist of method_id, args0, arg1, ... argN. Method id consists of 4 bytes and arguments are all 32 bytes. Method ids are created from the first 4 bytes of the hash of the methods string signature. (signature = baz(uint32,string32))

func (*ABI) UnmarshalJSON

func (abi *ABI) UnmarshalJSON(data []byte) error

UnmarshalJSON implements json.Unmarshaler interface

func (ABI) Unpack added in v1.4.0

func (abi ABI) Unpack(v interface{}, name string, output []byte) (err error)

Unpack output in v according to the abi specification

type Argument

type Argument struct {
	Name    string
	Type    Type
	Indexed bool // indexed is only used by events

Argument holds the name of the argument and the corresponding type. Types are used when packing and testing arguments.

func (*Argument) UnmarshalJSON

func (argument *Argument) UnmarshalJSON(data []byte) error

UnmarshalJSON implements json.Unmarshaler interface

type Arguments added in v1.8.0

type Arguments []Argument

func (Arguments) LengthNonIndexed added in v1.8.0

func (arguments Arguments) LengthNonIndexed() int

LengthNonIndexed returns the number of arguments when not counting 'indexed' ones. Only events can ever have 'indexed' arguments, it should always be false on arguments for method input/output

func (Arguments) NonIndexed added in v1.8.2

func (arguments Arguments) NonIndexed() Arguments

NonIndexed returns the arguments with indexed arguments filtered out

func (Arguments) Pack added in v1.8.0

func (arguments Arguments) Pack(args ...interface{}) ([]byte, error)

Pack performs the operation Go format -> Hexdata

func (Arguments) PackValues added in v1.8.2

func (arguments Arguments) PackValues(args []interface{}) ([]byte, error)

PackValues performs the operation Go format -> Hexdata It is the semantic opposite of UnpackValues

func (Arguments) Unpack added in v1.8.0

func (arguments Arguments) Unpack(v interface{}, data []byte) error

Unpack performs the operation hexdata -> Go format

func (Arguments) UnpackValues added in v1.8.2

func (arguments Arguments) UnpackValues(data []byte) ([]interface{}, error)

UnpackValues can be used to unpack ABI-encoded hexdata according to the ABI-specification, without supplying a struct to unpack into. Instead, this method returns a list containing the values. An atomic argument will be a list with one element.

type Event added in v1.4.0

type Event struct {
	Name      string
	Anonymous bool
	Inputs    Arguments

Event is an event potentially triggered by the EVM's LOG mechanism. The Event holds type information (inputs) about the yielded output. Anonymous events don't get the signature canonical representation as the first LOG topic.

func (Event) Id added in v1.4.0

func (e Event) Id() common.Hash

Id returns the canonical representation of the event's signature used by the abi definition to identify event names and types.

func (Event) String added in v1.8.0

func (e Event) String() string

type Method

type Method struct {
	Name    string
	Const   bool
	Inputs  Arguments
	Outputs Arguments

Method represents a callable given a `Name` and whether the method is a constant. If the method is `Const` no transaction needs to be created for this particular Method call. It can easily be simulated using a local VM. For example a `Balance()` method only needs to retrieve something from the storage and therefor requires no Tx to be send to the network. A method such as `Transact` does require a Tx and thus will be flagged `true`. Input specifies the required input parameters for this gives method.

func (Method) Id

func (method Method) Id() []byte

func (Method) Sig added in v1.4.0

func (method Method) Sig() string

Sig returns the methods string signature according to the ABI spec.


function foo(uint32 a, int b)    =    "foo(uint32,int256)"

Please note that "int" is substitute for its canonical representation "int256"

func (Method) String

func (method Method) String() string

type Type

type Type struct {
	Elem *Type

	Kind reflect.Kind
	Type reflect.Type
	Size int
	T    byte // Our own type checking
	// contains filtered or unexported fields

Type is the reflection of the supported argument type

func NewType

func NewType(t string) (typ Type, err error)

NewType creates a new reflection type of abi type given in t.

func (Type) String

func (t Type) String() (out string)

String implements Stringer


Path Synopsis
Package bind generates Ethereum contract Go bindings.
Package bind generates Ethereum contract Go bindings.

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