How can I execute a PHP file before using its content with another file?

Question

Situation

I’m mixing HTML & CSS with PHP variables, so that I can manage a lot of settings with just one config file. This is all working fine, but I’m trying to merge and minify the CSS now. And this causes a problem.

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Problem

The variables won’t be echoed into the compressed sheet because the PHP script won't be executed. And that is because file_get_contents() converts the content into a string.

---

Question

Is it in some way possible to execute the files first, and then grab their contents? Or grab their contents in another way, a way that they still will be executed?

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Files

config.php

$priColor = '#000';

base-stylesheet.php

/* CSS header defined */
/* config.php included */
body{
    background-color: <?= $priColor ?>;
}

specific-stylesheet.php

/* CSS header defined */
/* config.php included */
.site-specific-element{
    background-color: <?= $priColor ?>;
}

minified-stylesheets.php

// Set files that must be minified
$cssFiles = array(
    "base-styleseet.php",
    "specific-stylesheet.php"
);

// Get those files
$buffer = "";
foreach ($cssFiles as $cssFile) {
    $buffer .= file_get_contents($cssFile);
}

// Minify and echo them
minifyCSS($buffer);
echo $buffer;

index.php

<link rel="stylesheet" href="minified-stylesheets.php">

Answer 1

I think what you need to do is include the file into a PHP buffer and then minify the buffer

// Set files that must be minified
$cssFiles = array(
    "base-styleseet.php",
    “specific-stylesheet.php"
);

// Get those files
ob_start();
foreach ($cssFiles as $cssFile) {
    include($cssFile);
}

// Minify and echo them

$css = minifyCSS(ob_get_clean());
echo $css;

Answer 2

You already are familiar with the ob_start() method.

But I will show a better alternative (and faster):

Your main file:

$cssFiles = array(
    "base-styleseet.php",
    "specific-stylesheet.php"
);

$buffer = "";
foreach ($cssFiles as $cssFile) {
    $buffer .= include($cssFile);
}

minifyCSS($buffer);
echo $buffer;

Well, nothing much here. Just added a include() there...

But it won't work as intended, unless you do like this, for every file:

1. Create a heredoc with all the content
2. Return it

Using the base stylesheet as an example:

<?php

    //remember to escape the { chars        
    return <<<CSS
/* CSS header defined */
/* config.php included */
body\{
    background-color: $priColor;

    /* with an array */
    background-image: url('{$images['print']}');
    /* or */
    background-image: url('$images[print]');
\}
CSS;

^{* Ignore the broken syntax highlight}

And you are done.

No more nasty ob_start()!!!

Also, CSS comments use the /* */ syntax, // will be evaluated as an invalid CSS selector.