How Do Method Expressions Enable Passing Methods as Arguments in Go?

Method Expressions in Go

Method expressions in Go allow you to call a method with a custom object as the first argument. This can be useful when you need to pass a specific action to a function.

Understanding the Code Snippet

Consider the following Go code:

func main() {
    dog := Dog{}
    b := (*Dog).Bark // method expression
    b(&dog, 5)
}

type Dog struct {}

func (d *Dog) Bark(n int) {
    for i := 0; i < n; i++ {
        fmt.Println("Bark")
    }
}

In this example, a method expression is used to assign a function to the variable b. The method expression (*Dog).Bark associates the Bark method of the Dog type with a pointer receiver (*Dog).

When b is called, the Bark method is invoked with the dog object as the first argument and 5 as the second argument. The method prints "Bark" to the console five times.

Advantages of Method Expressions

• Method expressions allow you to pass a specific action to functions, even if the object is not known at compile time.
• They provide a way to create custom function types that can be used with other higher-order functions.

Example Usage

Method expressions can be used in various situations. For instance, you could define a helper function that takes a method expression and an object, and then performs an action based on the method:

func DoAction(f func(*Dog, int), d *Dog, n int) {
    f(d, n)
}

...

func main() {
    var b func(*Dog, int)
    if (shouldBark) {
        b = (*Dog).Bark
    } else {
        b = (*Dog).Sit
    }
    d := Dog{}
    DoAction(b, &d, 3)
}

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