How can i get the PHP magic constant __FILE__ work with Eclipse and PDT

Question

Lately when i was debugging some PHP file with XDebug (under Eclipse on Ubuntu) i came across a strange behaviour:

print(__FILE__);

resulted in

Answer 1

The output you get is not incorrect. __FILE__ is a special constant that gets evaluated at parser time. When the PHP script gets compiled, it would really read something like this:

// test.php

even though the script source was:

// test.php

This means that after parsing, there is no such "constant" __FILE__ at all, as it has already been replaced.

This means that if you do in an IDE, through DBGp's eval command eval -- __FILE__ it can not give you the __FILE__ with any filename. Instead, it uses the filename for the current context which is xdebug eval or in later versions, xdebug://debug-eval.

In essence, it's the same as doing this:

php -r 'eval("__FILE__;");'

Which also outputs:

Command line code(1) : eval()'d code

Xdebug looks for this sort of format, and changes it to xdebug://debug-eval so that it can actually debug into eval'ed code.

__FILE__ works as expected in PHP source code, as can be proven with this snippet: