Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func OnceFunc ¶ added in v1.2.0
func OnceFunc(f func()) (func(), func())
OnceFunc returns a function that invokes f only once. The returned function may be called concurrently.
If f panics, the returned function will panic with the same value on every call.
func OnceValue ¶ added in v1.2.0
func OnceValue[T any](f func() T) (func() T, func())
OnceValue returns a function that invokes f only once and returns the value returned by f. The returned function may be called concurrently.
If f panics, the returned function will panic with the same value on every call.
func OnceValues ¶ added in v1.2.0
func OnceValues[T1, T2 any](f func() (T1, T2)) (func() (T1, T2), func())
OnceValues returns a function that invokes f only once and returns the values returned by f. The returned function may be called concurrently.
If f panics, the returned function will panic with the same value on every call.
Types ¶
type Once ¶ added in v1.2.0
type Once struct {
// contains filtered or unexported fields
}
Once is an object that will perform exactly one action.
A Once must not be copied after first use.
In the terminology of the Go memory model, the return from f “synchronizes before” the return from any call of once.Do(f).
func (*Once) Do ¶ added in v1.2.0
func (o *Once) Do(f func())
Do calls the function f if and only if Do is being called for the first time for this instance of Once. In other words, given
var once Once
if once.Do(f) is called multiple times, only the first call will invoke f, even if f has a different value in each invocation. A new instance of Once is required for each function to execute.
Do is intended for initialization that must be run exactly once. Since f is niladic, it may be necessary to use a function literal to capture the arguments to a function to be invoked by Do:
config.once.Do(func() { config.init(filename) })
Because no call to Do returns until the one call to f returns, if f causes Do to be called, it will deadlock.
If f panics, Do considers it to have returned; future calls of Do return without calling f.
type ValFn ¶
type ValFn[T any] func() T
type ValsFn ¶
type ValsFn[T1, T2 any] func() (T1, T2)
func OnceVals ¶
func OnceVals[T1, T2 any](newFn func() (T1, T2)) ValsFn[T1, T2]
OnceVals returns a function that invokes f only once and returns the values returned by f. The returned function may be called concurrently.
If f panics, the returned function will panic with the same value on every call.
func OnceValsFn ¶
func OnceValsFn[T1, T2 any](newFn func() (T1, T2)) ValsFn[T1, T2]
OnceValsFn returns a function that invokes f only once and returns the value returned by f. The returned function may be called concurrently.
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