PHP Objects, Patterns, and Practice, Third Edition

CHAPTER 7 ■ WHAT ARE DESIGN PATTERNS? WHY USE THEM?

128

ME: I’m thinking of using a Composite.

B

OB: I don’t think you’ve thought that through.

OK, Bob didn’t agree with me. He never does. But he knew what I was talking about, and therefore

why my idea sucked. Let’s play that scene through again without a design vocabulary.

M

E: I intend to use a tree of objects that share the same type. The type’s

interface will provide methods for adding child objects of its own type. In this

way, we can build up complex combinations of implementing objects at

runtime.

B

OB: Huh?

Patterns, or the techniques they describe, tend to interoperate. The Composite pattern lends itself to

collaboration with Visitor:

M

E: And then we can use Visitors to summarize the ...