Comments on: Wrapping collections: Inheritance vs Composition

By: Wrapping about Collections

Wrapping about Collections — Tue, 09 Feb 2010 19:55:37 +0000

[...] how wrapping a collection can often create a more useful abstraction, then points to his debate in Wrapping collections: Inheritance vs Composition. It’s a good [...]

By: Reflective Perspective - Chris Alcock » The Morning Brew #397

Reflective Perspective - Chris Alcock » The Morning Brew #397 — Fri, 24 Jul 2009 07:42:02 +0000

[...] Wrapping collections: Inheritance vs Composition – Mark Needham talks about the two common techniques for wrapping collection classes using Inheritance or Composition, examining when each technique is more suited and looking at the ups and downs of each [...]

By: DCam

DCam — Thu, 23 Jul 2009 21:43:43 +0000

Several of the collection classes have wide, rich interfaces. If you inherit from them, certain types of behaviour can be difficult to add. For example, if you want to do some validation when adding to the collection there are a few places to override: []=, Add(), AddRange().

This is where it helps to have source and be able to see which methods are a the end of a delegation chain. Maybe it is only necessary to override a single method? Maybe AddRange() delegates to Add()?

For our PleaseSelectList(), we implemented our behaviour in the constructor. (If I recall correctly.) Constructors are always overrideable, in a sense, and the base class’s constructors are never exposed to clients of the derived type. This is not the case for other parts of the object.