I came to know about mixins.So my doubt is, is it possible to use mixins in php?If yes then how?
First google result for "php5 mixin": http://www.sitepoint.com/forums/php-application-design-147/ruby-like-mixins-php5-332491.html
First google result for "php mixin": http://www.advogato.org/article/470.html
Short answer: yes, but not natively (yet, evidently, as @mchl notes). Check those out.
Longer answer: if you're using runkit, checkout runkit_method_copy(): "Copies a method from class to another."