With all the functionality and flexibility available in PHP 5, it is no surprise that it consists of several thousand files and over one million lines of source code. Equally unsurprising is the necessity of a build system to manage so much data. This section describes how to set PHP up for extension development, the layout of an extension within the PHP source tree, and how to interface your extension with the build system.
In a typical PHP installation, the need for high performance almost always results in optimization at the cost of debugging facilities. This is a reasonable tradeoff for production use, but when developing an extension it falls short. What we need is a build of PHP which will give us some hints what has gone wrong when something does.
The Zend Engine provides a memory manager which is capable of tracking memory leaks in extensions and providing detailed debugging information. This tracking is disabled by default, as is thread-safety. To turn them on, pass the --enable-debug and --enable-maintainer-zts options to configure, along with whatever options you typically use. For instructions on building PHP from source, see the instructions at General Installation Considerations. A typical configure line might look like this:
$ ./configure --prefix=/where/to/install/php --enable-debug --enable-maintainer-zts --enable-cgi --enable-cli --with-mysql=/path/to/mysql