1
edit
Changes
→Applicability
<li>we want to hide the implementation of an abstraction completely from clients</li>
<li>we want to share an implementation among multiple objects, and this fact should be hiddent from the client</li>
<li>useful in graphic and windowing systems that need to run over multiple platforms</li>
<li>useful any time we need to vary an interface and an implementation in different ways</li>
</ul></ul>
