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How does wordpress know about its functions?

Answer 1

+1 A:

Most likely, index.php is being included in another file and that file either defines the get_header() function or - more likely - contains yet another included php file which in turns defines the get_header() function.

You have to understand that the php include and require functions behave like an in-line include. It simply treats the include file as being part of the original script.. a big concatenated script (so not really like an import in Java)

You may want to start at the .htaccess file which will tell you which .php file is assigned to handle the request. Based on what you said in your question, it will probably not be index.php. When you find the top-most php script, you can work your way from there with the includes and requires..

Miky Dinescu 2009-12-03 18:57:30

Whoops, you are correct about it not being similar to java import, thanks for pointing that out!

Trajanus 2009-12-03 19:42:49

Answer 2

A:

in c and in java you declare the import at the top of you files. In php you can set the includes almost anyware you want.

so this is valid:

<?php 
// define some functions
?>
<html>
<head>
<?php
include('head.php');
?>
</head>
<body></body></html>

it is possible that these get_header() methods are declared somewhere before the index.php page is included.

If you want to leave out the <?php get_header(); ?> then there will be no problem

Robert Cabri 2009-12-03 18:58:20

Answer 3

+4 A:

Themes' index.php file is not the main file that's processed, that one resides in the root directory of your wordpress installation. It calls several files setting up the environment and then loads the template. You might want to look in the wp-content/plugins directory, maybe starting with the globals.php file to tweak some of the magic.

Also the wp-includes directory contains interesting files, the get_header() function is defined in general-template.php in that directory.

kemp 2009-12-03 19:01:03

Thanks! Exactly the sort of answer I was looking for :)

Trajanus 2009-12-03 19:42:04

Answer 4

+2 A:

Specifically in theme php files, such as say index.php. The very first thing in most theme's index.php file is a call to get_header() which is most certainly not not defined in index.php, so how does it know about that function?

A theme's index.php file is never executed on its own. All requests to a WordPress install go through the main WordPress index.php file.

ceejayoz 2009-12-03 19:01:54

Answer 5

+4 A:

The index.php in each theme isn't ever called directly, rather those are included by other files in Wordpress.

get_header is actually defined in wp-includes/general-template.php.

The templates files are loaded by require_once function calls in the load_template function of wp-includes/theme.php

jimdahl 2009-12-03 19:01:55

Answer 6

A:

Take a look at all the documentation available: PHP Function Reference « WordPress Codex

songdogtech 2009-12-03 19:18:06

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How does wordpress know about its functions?

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