Why use if function_exists?

Posted by Prem Tiwari | Updated on

Checking to see if built in WordPress functions exist before calling them is for backward compatibility which IMHO is not needed.

So if you see if ( function_exists( 'register_nav_menus' ) ) the theme author is supporting versions earlier than 3.0.

You still sometimes see if ( function_exists( 'dynamic_sidebar' ) ) Why? I couldn’t tell you because dynamic_sidebar was introduced.

Another reason to use it is to make your theme or plugin pluggable. A pluggable function is one that can be overridden in a child theme or another plugin.

This is done on the definition not the call and you use the ! operator to make sure it doesn’t already exist before you define it.


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