TIL: Nested functions in PHP

nested-cannot-call-from-other-method-if-not-defined.php

<?php

class NestedFunctions
{
    public function fn1()
    {
        function nested_fn() { echo 'yay' . "\n"; }
        nested_fn();
    }

    public function fn2()
    {
        nested_fn();
    }
}

$nested = new NestedFunctions();
$nested->fn2();
$nested->fn1();

// output: http://3v4l.org/hrNsX

nested-cannot-redeclare1.php

<?php

class NestedFunctions
{
    public function fn1()
    {
        function nested_fn() { echo 'yay' . "\n"; }
        nested_fn();
    }
}

$nested = new NestedFunctions();
$nested->fn1();
$nested->fn1();

// output: http://3v4l.org/buK93

nested-cannot-redeclare2.php

<?php

class NestedFunctions
{
    public function fn1()
    {
        function nested_fn() { echo 'yay' . "\n"; }
        nested_fn();
    }

    public function fn2()
    {
        function nested_fn() { echo 'yay' . "\n"; }
        nested_fn();
    }
}

$nested = new NestedFunctions();
$nested->fn1();
$nested->fn2();

// output: http://3v4l.org/WABfQ

nested-works-call-from-other-method.php

<?php

class NestedFunctions
{
    public function fn1()
    {
        function nested_fn() { echo 'yay' . "\n"; }
        nested_fn();
    }

    public function fn2()
    {
        nested_fn();
    }
}

$nested = new NestedFunctions();
$nested->fn1();
$nested->fn2();

// output: http://3v4l.org/2V57M

nested-works.php

<?php

class NestedFunctions
{
    public function fn1()
    {
        function nested_fn() { echo 'yay' . "\n"; }
        nested_fn();
    }
}

$nested = new NestedFunctions();
$nested->fn1();

// output: http://3v4l.org/5brpq