CODEWITHSUNDEEP
phpclassfunctiontemplates
nderjung
nderjung

Reputation: 1617

PHP: Function within a function then include with internal functions

I have tested the following and it doesn't work. Is there a similar way of achieving this?

A compiling class which formulates a template:

private function include_header () {
    function _metadata () {
        // Metadata compiler
        return $metadata;
    }
    include (path . "header.php");
}

header.php

<html>
<head>
    <?php
        _metadata ();
    ?>
    <title>Hello Stackoverflow!</title>
</head>
<body>
    ...

The _metadata (); function is only available within the include_header (); function - nowhere else in the class. I don't want to have to write $this->_metadata (); in the template file only _metadata ();. Is that achievable?

Alternatively one could create an external file, for example functions.php which has the underscore functions specifically for the template - but I'd much rather see if the original query is possible.

Thank you in advance.

Upvotes: 2

Views: 586

Answers (2)

entropid
entropid

Reputation: 6239

You can't define nested function in PHP. I mean, you can, but there's no purpose since they'll have a global scope and therefore they will be callable from any point of the script.

But you actually don't need to define a _metadata() function, you can just execute all the function logic inside include_header() and then store everything in the variable $metadata, which will be printed in the include with a simple <?php echo $metadata; ?>.

If you really need to define a function you can use the function create_function() or (just for PHP > 5.3) an anonymous function. Since they will be encapsulated inside a variable, which has a function scope, they won't be available outside.

Upvotes: 1

lonesomeday
lonesomeday

Reputation: 237975

From the manual:

All functions and classes in PHP have the global scope - they can be called outside a function even if they were defined inside and vice versa.

So, essentially, you can't do what you're trying to do. _metadata will always be a global function if it is defined with the function _metadata() { syntax. The normal function syntax only supports global functions.

However, PHP 5.3 introduces something called "anonymous functions". These can be assigned to a variable. Since variables can be scoped to a function scope (they are only global if you explicitly say so), you can limit them in this way.

For instance:

$_metadata = function() {
    // Metadata compiler
    return $metadata;
};

This could then be called in header.php with:

<?php $_metadata(); ?>

Note that this is less stable: it is, for instance, possible to redefine the variable to be a different anonymous function – or indeed not a function at all. The safest solution, ultimately, is to use a templating language that solves these issues for you. If not, you can either accept that you'll have to use global functions or anonymous functions.

Upvotes: 4

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