An introduction to the syntax of one way channel in golang

This article is mainly about golang one-way channel grammar related content, share for your reference and study, the following words are not enough, let's have a look at the detailed introduction:

Today, be free and at leisure adds 1 golang grammar. When I think of the usage of context, I come across an channel grammar I haven't seen before:

// A Context carries a deadline, cancelation signal, and request-scoped values
// across API boundaries. Its methods are safe for simultaneous use by multiple
// goroutines.
type Context interface {
 // Done returns a channel that is closed when this `Context` is canceled
 // or times out.
 Done() <-chan struct{}
 
 // Err indicates why this Context was canceled, after the Done channel
 // is closed.
 Err() error
 
 // Deadline returns the time when this Context will be canceled, if any.
 Deadline() (deadline time.Time, ok bool)
 
 // Value returns the value associated with key or nil if none.
 Value(key interface{}) interface{}
}

Now, look at: Done() <- chan struct{} How is the declaration of an interface function so strange? So let's factor 1.

Done() chan struct{} : If the function definition is changed to this, the meaning is,

Function name Done, argument (), return value chan struct{} . Take the return value alone, it is 1 pipe chan, and the internal data type is struct{} . Take struct{} alone, we are familiar with it type Name struct{a int, b bool} To define the type of a structure, struct{... } is the definition of the structure, and map[string]int this definition is the same, type just gives it an individual name.

<- chan struct{} If we look at this expression alone, we know if ch := make(chan struct{}) , then < -ch takes data from the pipe. but chan struct{} Type, not variable. Can you get data from a type?

Actually, <-chan int This is still a pipe type, which is called one-way channel. If it is <-chan int Can only read not write pipe (also cannot close), if is Done() chan struct{} 0 Can only write unreadable pipe (can close), that's all!

conclusion