This article mainly introduces relevant content about golang one-way channel grammar. We will share it for your reference and learning. Let’s not say much below, let’s take a look at the detailed introduction:
Today I have nothing to do and add to the grammar knowledge of golang. I remember to see the usage of context, but I encountered an unprecedented channel syntax:
// 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 , ok bool)
// Value returns the value associated with key or nil if none.
Value(key interface{}) interface{}
}
Pay attention to:Done() <- chan struct{}, Why is the declaration of an interface function so strange? Let’s break it down below.
Done() chan struct{} : If the function definition is changed to this, its meaning is,
- Function name Done, parameter(), return value
chan struct{}。 - Take the return value separately, it is a pipeline chan, and the internal data type is
struct{}。 - Take struct{} as an example, we are familiar with it
type Name struct{a int, b bool}To define the type of a structure in this way, struct{…} is actually to define the structure, which is the same as map[string]int, type just gives it an alias.
<- chan struct{}: Look at this expression alone, we know ifch := make(chan struct{}) , then <- ch is to retrieve data from the pipeline. butchan struct{}Is it a type rather than a variable, and can I actually get data from a type? ?
actually<-chan intIt is still a pipeline type, which is called a one-way channel. in the case of<-chan int, which means that it is a pipe that can only be read but not written (and cannot be closed).chan <- int, it means that it is a pipe that can only be written but not read (can be closed), that's all!
Summarize
The above is the entire content of this article. I hope that the content of this article will be of some help to everyone’s learning or using Go. If you have any questions, you can leave a message to communicate. Thank you for your support.