Reconstruct / get source code of a PHP function

Can I programmatically get the source code of a function by its name?

Like:

function blah($a, $b) { return $a*$b; }
echo getFunctionCode("blah");

is it possible?

Are there any php self-descriptive functions to reconstruct function/class code? (I mean instead of getting source code right from the source file.)

In Java there exists: http://java.sun.com/developer/technicalArticles/ALT/Reflection/