Law of demeter

[juan_gandhi]

Intro:
The Law of Demeter for functions requires that a method M of an object O may only invoke the methods of the following kinds of objects:

1. O itself
2. M's parameters
3. any objects created/instantiated within M
4. O's direct component objects

In particular, an object should avoid invoking methods of a member object returned by another method.

[Poll #1087502]

Comments

[xryun-porosyan.livejournal.com]

In many cases #3 may contradict with "an object should avoid invoking methods of a member object returned by another method".

Another method might as well be a factory method, i.e. a method responsible for the creation/instantiation of a new object.

[sab123.livejournal.com]

If an object's methods are not to be called, most of the time that object should not be returned/exposed at all.