Go Methods

How it works

A method is a function with a receiver. A value receiver gets a copy; a pointer receiver can change the original value. Use consistent receiver choices when a type owns mutable state, and validate a requested change before committing it.

Run this Go example

Install Go separately from the official Go downloads and check go version in a new terminal. The reviewed baseline is Go 1.27.3 on Windows amd64; the authored syntax and standard-library APIs require Go 1.22 or newer. Save the complete source below as methods.go in a learning folder, then run go run methods.go from that folder. These examples use only the standard library.

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Download the complete methods.go · Download all source files with hash checks

For the optional collection download, save download-examples.mjs in a new learning folder and run node download-examples.mjs. A local preview uses node download-examples.mjs http://127.0.0.1:8000/examples/go/. The downloader refuses an existing bhylu-go-examples folder and installs or executes no Go code.

Example

package main

import (
	"fmt"
)

type Desk struct{ Capacity, Used int }

func (d *Desk) Accept(amount int) bool {
	if d == nil || d.Capacity < 0 || d.Used < 0 || d.Used > d.Capacity || amount <= 0 || amount > d.Capacity-d.Used {
		return false
	}
	d.Used += amount
	return true
}

func main() {
	desk := Desk{Capacity: 5, Used: 2}
	fmt.Println(desk.Accept(2), desk.Used)
	fmt.Println(desk.Accept(2), desk.Used)
}

Expected result

true 4
false 4

The first request fits. The second is refused without changing Used. Comparing amount with Capacity-Used avoids an addition that could overflow when the contract is generalised.