How can I deploy a chunk of code with one line of PHP?

Question

Recently in a huge flurry of Wordpress related googling I came across a possible solution to my problem of that time which used a method I hadn't come across before: Part of the process was including in the functions.php file the code which would have otherwise been placed in the template files of the site. That code was then "injected" into the theme files with one simple line of code. Something like:

<?php insert_custom_code(); ?>

I loved how clean this kept the template files, by allowing me to write the code related to some trickery and tucking it away in functions. Now I've also learned about creating site specific plugins so I can wrap that sort of stuff up in even tidier packages. Unfortunately that specific solution didn't work for my problem at that time, and I've lost that information.

I think this is a straight forward and standard part of Wordpress work - especially related to plugin and theme development, but I'm not sure what it's called or how to find it. So my question is: Does anyone know what this is called? Or where it might live in the wordpress codex or any other documentation that might help? I really appreciate it.

Answer 1

It is simple PHP language style of declaring and calling a function! We are essentially calling a function which was defined/declared in functions.php or any included file.

In PHP we can call any function with its name and (); eg for a function named myFunction, we can call it as myFunction();

http://www.w3schools.com/php/php_functions.asp

This is same as we call other built-in WordPress functions like, get_the_title(); or the_title(); etc

And to declare your own custom functions in functions.php

You may use this syntax:

function your_function_name(){
     //your php code here

}

Then as functions.php is included by WordPress in all theme files, you can then simply call this function in any theme php file as:

your_function_name();