How to create a list of all built-in PHP functions a project makes use of?
<p>Background: PHP allows providers to disable functions (directive "disable_functions"). So in order to get to know if your project is running on a specific server you'll have to check:</p>

<ol>
<li>What built-in (=excluding user-defined) functions is your to-be-deployed project using?</li>
<li>Are the functions available on the specific host?</li>
</ol>

<p>(Question (2) is a trivial loop over the result (1) with <code>function_exists</code>.)</p>

<p>In order to get the harvesting working (=a mostly complete set of built-in functions used on the development servers) one could create a list of functions with <code>get_loaded_extensions()</code>, <code>get_extension_funcs()</code> and <code>get_defined_functions()</code> (and access it's 'internal' array for the built-in functions).</p>

<p>Now the question: How would you extract/grep the built-in PHP functions used in the project from your (possibly hundreds of) source files?</p>

<p>It could be a nice PERL job or somethig like that. How would you do it?</p>
