Program to an interface not an implementation in php
<p>Once of the major design principles is program to an interface not an implementation.  Is this even possible in php or any other weakly typed language.</p>

<p>EDIT:</p>

<p>I maybe didnt write the question as clearly as i should have.  I dont mean that php cant use interfaces - it obvisouly can.  I mean does the design principle "program to an interface and not an implementation" become redundant in weakly typed languages.</p>
