Xdebug is a debugging and productivity extension for PHP

Xdebug and provides a range of features to improve the PHP development
experience.

Step Debugging
A way to step through your code in your IDE or editor while the script is
executing.

Improvements to PHP's error reporting
An improved var_dump() function, stack traces for Notices, Warnings, Errors
and Exceptions to highlight the code path to the error

Tracing
Writes every function call, with arguments and invocation location to disk.
Optionally also includes every variable assignment and return value for
each function.

Profiling
Allows you, with the help of visualisation tools, to analyse the
performance of your PHP application and find bottlenecks.

Code Coverage Analysis
To show which parts of your code base are executed when running unit tests
with PHP Unit.

Wed, Jul 18, 2007 - xdebug 2.0.0

+ Changes:
- Put back the disabling of stack traces - apperently people were relying
on this. This brings back xdebug_enable(), xdebug_disable() and
xdebug_is_enabled().
- xdebug.collect_params is no longer a boolean setting. Although it worked
fine, phpinfo() showed only just On or Off here.
- Fixed the Xdebug version of raw_url_encode to not encode : and \. This is
not necessary according to the RFCs and it makes debug breakpoints work
on Windows.

= Fixed bugs:
- Fixed bug #291: Tests that use SPL do not skip when SPL is not available.
- Fixed bug #290: Function calls leak memory.
- Fixed bug #289: Xdebug terminates connection when eval() is run in the
init stage.
- Fixed bug #284: Step_over on breakpointed line made Xdebug break twice.
- Fixed bug #283: Xdebug always returns $this with the value of last stack
frame.
- Fixed bug #282: %s is not usable for xdebug.profiler_output_name on
Windows in all stack frames.
- Fixed bug #280: var_dump() doesn't display key of array as expected.
- Fixed bug #278: Code Coverage Issue.
- Fixed bug #273: Remote debugging: context_get does not return context id.
- Fixed bug #270: Debugger aborts when PHP's eval() is encountered.
- Fixed bug #265: XDebug breaks error_get_last() .
- Fixed bug #261: Code coverage issues by overloading zend_assign_dim.

+ DBGP:
- Added support for "breakpoint_languages".