In go language, function is a type

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summary ( Remember the following three sentences )

1、 function , It is also a kind of type ( Pay special attention to )
2、 function , I can assign a value to Variable ( want special Be careful )


3、 function , It can be used as Parameters , To pass

package func5_test

import (
	"testing"
	"fmt"
)

// Make a statement fire function 
func fire()  {
	fmt.Print("--->this is fire func")
}

func study(str string)  {
	fmt.Printf("--->I'm studying %s", str)
}

//  test , Whether the function is assigned to a variable 
func TestFuncVariable(t *testing.T)  {
	//  Declare variables f, The type is func type , Function type 
	//  Put the variable  f  Declare as  func()  type ,
	//  call f When , It's actually calling theta fire function , here  f  It is commonly known as “ Callback function ”, 
       //  here  f  The value of is  nil
	var f func()

	f = fire

	f()
}

//  test , Whether the function is assigned to a variable 
func TestStudy(t *testing.T)  {

	st := study

	st("English")
}

//  test , Whether the function type can be passed as a parameter 
func learning(f func())  {
	fmt.Printf("--->this is running func")
	f()
}

func TestFuncParams(t *testing.T)  {
	f := fire
	//  Pass the function as an argument 
	learning(f)
}