Type ‣ Undefined ᴾᴴᴾ - chung-leong/zigar GitHub Wiki

JavaScript | PHP

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The literal undefined in Zig is represented as null in PHP. You will only encounter it if you explicitly export undefined.

pub const Undefined = undefined;

<?php

$m = zigar_use(__DIR__ . '/undefined-example-1.zig');

debug_zval_dump($m->undefined_value);

NULL

Assigning undefined to a variable would not yield undefined on the JavaScript side.

pub var number: i32 = undefined;

<?php

$m = zigar_use(__DIR__ . '/undefined-example-2.zig');

debug_zval_dump($m->number);

int(0)

As @TypeOf(undefined) is a comptime type, you can only put it into a struct if you make it a comptime field:

pub const NumberAndUnknown = struct {
    number: i32,
    comptime unknown: @TypeOf(undefined) = undefined,
};

<?php

$m = zigar_use(__DIR__ . '/undefined-example-3.zig');

$struct = new $m->NumberAndUnknown(number: 1234);
print_r($struct);

NumberAndUnknown Object
(
    [number] => 1234
    [unknown] => 
)

It's different from void, which is a runtime type.

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Types