deferred statements in php

gistfile1.txt

'defer' puts statements on a LIFO stack and executes them right before the function returns.

<?php
function fooz() {                               function fooz() {
    defer echo 'bai';                           
    defer echo 'thx';      ... becomes ...
    echo 'k';                                       echo 'k';
                                                    echo 'thx';
                                                    echo 'bai';
}                                               }
?>

'defer' helps to re-use clean-up code and to preserve contexts.

<?php
function f($a = true) {
    $fh = fopen('file.txt', 'r');
    if (!$fh) {
        return false;
    }
    
    defer fclose($fh);
    
    if ($a) {
        // do stuff ...
        return 'something';
    }
    
    // do other stuff ...
    
    return 'something different';
}
?>

... becomes ...

<?php
function f($a = true) {
    $fh = fopen('file.txt', 'r');
    if (!$fh) {
        return false;
    }
    
    if ($a) {
        // do stuff ...
        $ret = 'something';
        fclose($fh);
        return $ret;
    }
    
    // do other stuff ...
    
    $ret = 'something different';
    fclose($fh);
    return $ret;
}
?>

Finally a silly example with a closure.

<?php
function foo($i) {
    defer function() use (&$i) {
        $i++;
    }();
    
    $i *= 10;
    return $i;
}
?>

... becomes ...

<?php
function foo($i) {
    $i *= 10;
    function() use (&$i) {
        $i++;
    }()
    return $i;
}
?>

<?php
foo(1);  //  11
foo(5);  //  51
foo(20); // 201
?>