defer in Odin

Cleanup declared next to the thing it cleans: defer runs at scope exit, in reverse.

package main

import "core:fmt"

brew :: proc() {
    // defer runs at scope exit, last-declared first.
    fmt.println("kettle on")
    defer fmt.println("kettle off")
    defer fmt.println("pour the cup")
    fmt.println("three minutes steeping")
}

main :: proc() {
    brew()
    fmt.println("milk first, obviously")
}

How it works

1. Each defer is registered when its line is reached, not when it runs.
2. At scope exit they fire last-declared first: pour the cup, then kettle off.
3. The pattern keeps acquisition and release adjacent in the source.

Keywords and builtins used here

• defer
• import
• package
• proc

The run, in numbers

Lines

16

Characters to type

294

Tokens

66

Three-star pace

75 tpm

At the three-star pace of 75 tokens a minute, this run takes about 53 seconds.

Type this snippet

Step 1 of 3 in Idioms, step 16 of 27 in Language basics.

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defer in other languages

• Swift
• Zig