Defining methods in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a method in Go?

A method in Go is a function with a special receiver argument. It is like a function tied to a specific type, allowing you to call it using the dot notation on values of that type.

intermediate

How do you define a method with a pointer receiver in Go?

You define a method with a pointer receiver by specifying the receiver as a pointer type in parentheses before the method name, for example:

func (p *Person) UpdateName(newName string) { p.Name = newName }

This allows the method to modify the original value.

intermediate

What is the difference between a value receiver and a pointer receiver in Go methods?

A value receiver gets a copy of the value, so changes inside the method do not affect the original. A pointer receiver gets the address, so changes inside the method affect the original value.

intermediate

Can methods be defined on any type in Go?

No, methods can only be defined on named types declared in the same package. You cannot define methods on built-in types or types from other packages.

beginner

Example: Define a method called Greet for a struct Person that prints a greeting message.

<pre>package main

import "fmt"

type Person struct { Name string }

func (p Person) Greet() {
    fmt.Println("Hello, my name is", p.Name)
}</pre>

What does the receiver in a Go method specify?

A The type the method belongs to

B The return type of the method

C The package where the method is defined

D The name of the method

The receiver specifies the type the method is associated with, allowing the method to be called on values of that type.

Which receiver type allows a method to modify the original value?

A Value receiver

B Interface receiver

C Constant receiver

D Pointer receiver

Pointer receivers receive the address of the value, so changes inside the method affect the original value.

Can you define a method on the built-in type int in Go?

A No, never

B Yes, always

C Only if int is declared in your package

D Only if int is a pointer

You cannot define methods on built-in types like int directly.

How do you call a method named Print on a variable p of type Person?

A Print(p)

B p.Print()

C Person.Print(p)

D Print.Person(p)

Methods are called using dot notation on the variable: p.Print()

What happens if you define a method with a value receiver and modify the receiver inside the method?

A The program will not compile

B The original value is changed

C Only the copy inside the method changes

D The method runs twice

With a value receiver, the method works on a copy, so changes do not affect the original value.

Explain how to define a method in Go and the role of the receiver.

Think about how methods are like functions tied to a type.

Describe the difference between pointer and value receivers and when to use each.

Consider if you want the method to change the original data or not.