交换两个函数执行顺序的简写

Question

I'm looking for an abbreviated way to write the following logic in Php:

if condition do
   function b
   function a
else do
   function a
   function b

Or rather, a simple way to swap the order that functions a and b are executed.

This is what I've come up with so far:

!$swap && a(); // Where $swap is a boolean
b();
$swap && a();

A use case could be changing the rendering order of display output e.g. html.

Answer 1

You can do this with a loop consisting of two iterations. With an if/else containing each function calls as statements within the loop. A flag determines which function to run. After one iteration the flag is toggled, so next time the other function runs:

function a() {
    echo 'a';
}

function b() {
    echo 'b';
}

function c($flip = false) {

    for($i=0; $i<2; $i++) {
        if(! $flip) {
            a();
        } else {
            b();
        }
        $flip = ! $flip; // On next run the other statement will run
    }

}

c($flip = false);
c($flip = true);

// Outputs: abba

Or using the ternary operator:

function d($flip = false) {

    for($i=0; $i<2; $i++, $flip=!$flip) {
        !$flip ? a() : b();
    }

}

In a html view:

<?php for($i=0; $i<2; $i++) { if(! $flip) { // Change the block display order if flip is true. ?>

    <h2>Block Foo</h2>
    <p>...</p> 

<?php } else { ?>

    <h2>Block Bar</h2>
    <p>...</p>

<?php } $flip = !$flip; } ?>

The context being that I wrote a CMS module, and wanted a simple option for the end user to change the order of html, without overriding templates. I hope someone finds this useful.