Programming PHP

This will put a php binary in your /usr/local/bin directory. The configure line above
adds MySQL, PostgreSQL, and zlib support. While you don’t need them to develop
your extension, they won’t get in the way, and it is a good idea to have a php binary
that can run complex web applications directly from the command line.
Just to make sure it worked, test it:
% /usr/local/bin/php -v
4.2.0-dev
Planning Your Extension
As much as you probably just want to dive in and start coding, a little bit of planning
ahead of time can save you a lot of time and headaches later. The best way to
plan your extension is to write a sample PHP script that shows exactly how you plan
to use it. This will determine the functions you need to implement and their arguments
and return values.
For example, take a fictitious rot13 * extension that might be used as follows:
From this we see that we need to implement a single function, which takes a string as
an argument and returns a string. Don’t let the simplicity of the example fool you—
the approach we’ll take holds for extensions of any complexity.
Creating a Skeleton Extension
Once you have planned your extension, you can build a skeleton with the ext_skel
tool. This program takes a .def file, which describes the functions your extension will
provide. For our example, rot13.def looks like this:
string rot13(string arg) Returns the rot13 version of arg
This defines a function that returns a string and takes a string argument. Anything
after the close parenthesis is a one-line description of the function.
The other types valid in a .def file are:
void
For functions that return nothing or take no arguments
bool
Boolean
* rot13 is a simple encryption algorithm that rotates the English alphabet by half its length. “a” becomes “n”
and “z” becomes “m,” for example.
320 | Chapter 14: Extending PHP
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