Re: Inheritance versus Composition

From:
Eric Sosman <esosman@acm-dot-org.invalid>
Newsgroups:
comp.lang.java.help
Date:
Thu, 15 Mar 2007 08:10:07 -0400
Message-ID:
<UaydnZR51JwrqmTYnZ2dnUVZ_v6tnZ2d@comcast.com>
printdude1968@gmail.com wrote:

On Mar 14, 11:12 pm, Eric Sosman <esos...@acm-dot-org.invalid> wrote:

printdude1...@gmail.com wrote:

I am reading the book Learning Java (O'Reilly) and there is a section
which says to favor composition over inheritance. Having no
experience with composition, I am wondering what the general concensus
of the group is. Which is better, inheritance or composition. [...]

     Which is better, mitosis or meiosis?

     Which is better, ski-jumping or prestidigitation?

     Which is better, black or sour?

     Which is better, waltz or octopus?

     (In other words, you have asked a question that makes no
sense. You do not understand the words you are using; this is
a natural state of affairs for a beginner, but the cure is to
gain an understanding of the terms, not to engage in a debate
over the relative merits of phrenology and eschatology.)


I am not attempting to engage in a debate, I am only asking for
opinions. It seems to me that the other responders to my question
were
able to give me good things to ponder. As it turns out, the question
I ask is posed due to something I read in a book called Learning Java
(as I stated in my original post) so it seems to me that it is quite
valid for me to ask questions about something I read in the very early
stages of a book.


     I suspect I may have offended you, which was not my intent.
If I have done so, I ask your forgiveness.

     The reason I think your question makes no sense is that it
asks "which is better" but doesn't say anything about "for what
purpose?" Mitosis is not "better than" meiosis; they are
different (although related) processes with different functions.
If you want to make red blood cells mitosis is better than
meiosis; if you want to make eggs it's the other way around.

     Similarly with inheritance and composition: They are related
(both are ways of deriving a more specialized construct from a
more general substrate), but they are different and serve different
purposes. Neither is "better" than the other in isolation, not
until the purpose enters the picture.

     Which is better, a bicycle or a banana? It depends on whether
your purpose is to get from Here to There, or from Hungry to Fed.

--
Eric Sosman
esosman@acm-dot-org.invalid

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