promise

README

gopromise

Like Node.JS Promises, but in Go.

Documentation

Index

• type DeferredPromise
  • func NewDeferredPromise[T any]() DeferredPromise[T]
• type Func
• type Promise
  • func NewPromise[T any](fn Func[T]) Promise[T]
• type RejectFunc
• type ResolveFunc
• type Result

Types

type DeferredPromise

type DeferredPromise[T any] interface {
	Promise[T]

	// Run causes the DeferredPromise to call the passed Func,
	// thus starting the Promise lifecycle.
	// Run is multiprocess-safe: after the first call, subsequent calls
	// will do nothing.
	Run(Func[T])

	// Started returns whether or not Run has been called for
	// this DeferredPromise.
	Started() bool
}

DeferredPromise is a Promise which isn't initialized with a Func; instead, a DeferredPromise begins its lifecycle when Run is called.

func NewDeferredPromise

func NewDeferredPromise[T any]() DeferredPromise[T]

NewDeferredPromise returns a DeferredPromise.

type Func

type Func[T any] func(ResolveFunc[T], RejectFunc)

Func represents a wrapper function, to be wrapped around functions which are being called by a Promise.

type Promise

type Promise[T any] interface {
	// Resolve blocks until this Promise's execution finishes and
	// a Result is returned.
	Resolve() Result[T]

	// ResolveAsync returns a chan(Result) with a buffer size of 1, which
	// can be utilized in any way desired.
	ResolveAsync() <-chan Result[T]

	// Fulfilled returns true if this Promise resolved successfully.
	// More specifically, it returns true if the result of Err is nil;
	// the value returned by Result _can_ still be nil even if Fulfilled returns true.
	Fulfilled() bool

	// Rejected returns true if this Promise did not resolve successfully - specifically,
	// if the return result of Err is not nil.
	// Rejected will return false if the result of both Err and Result are nil.
	Rejected() bool
}

Promise provides an interface for types which fetch data or calculate results asyncronously, and can then wait for the result to return.

func NewPromise

func NewPromise[T any](fn Func[T]) Promise[T]

NewPromise returns a Promise. Upon instantiation, the passed Func is called in a goroutine which stores the returned data/error.

type RejectFunc

type RejectFunc func(error)

RejectFunc is a function passed to functions called by Promise, to be called if they return an error.

type ResolveFunc

type ResolveFunc[T any] func(T)

ResolveFunc is a function passed to functions called by Promise, to be called by those functions if they successfully return a result.

type Result

type Result[T any] interface {
	// Result returns the result of a Promise function call,
	// or nil if Err != nil
	Result() *T

	// Err returns any resultant error of a Promise function call.
	Err() error
}

Result is the result data returned by a function called by a Promise.