Go Methods: Receiver vs. Parameter: What\'s the Difference?

Method Binding in Go: Understanding Parameters vs. Receivers

In Go, methods are closely related to types. When defining a method for a type, you can specify whether it should be attached directly to the type or passed as an argument. This concept, known as method binding, is central to understanding Go's programming model.

Consider the following method signature:

func (p *Page) save() error {
    // ...
}

Here, p is the receiver, which is a special kind of parameter. In Go, the receiver is always the first parameter of a method, and it explicitly identifies the type to which the method is being attached. In this case, save is attached to the type *Page, which represents a pointer to a Page struct.

The receiver allows methods to access the instance data of the receiving object. When a method is invoked, the receiver is automatically bound to the underlying instance. This binding is transparent to the caller, but it gives the method access to the instance's fields and methods.

In contrast, regular parameters are passed as values, meaning they are copies of the actual data. They cannot be used to access or modify the caller's instance data.

To further clarify the distinction between receiver and parameters, consider the following code:

var p = new(Page)
p.save()
(*Page).save(p)

Both the last two lines represent exactly the same method call, demonstrating that the receiver is just a special form of parameter that is bound to the instance represented by the receiver value.

In conclusion, the receiver in Go's method signature is a special kind of parameter that binds the method to the type of the instance on which it is being invoked. This allows methods to access and manipulate the instance's data, while parameters are passed as values and cannot modify the caller's instance. Understanding this distinction is essential for effective use of methods in Go.

The above is the detailed content of Go Methods: Receiver vs. Parameter: What\'s the Difference?. For more information, please follow other related articles on the PHP Chinese website!