Subj : Re: Polymorphism sucks [Was: Paradigms which way to go?]
To   : comp.programming,comp.object
From : topmind
Date : Tue Jun 28 2005 06:20 pm

>
> > Copy-and-paste actually *reduces* coupling because it lets things be
> > independent, for example. Thus, if reducing coupling is always good,
> > then copy-and-paste is always good.
>
> It may appear to reduce coupling, but as has been said, it creates an
> invisible (to the source) web of coupling that needs to be documented
> and maintained by the developer.


Yes, but that is a nebulous form of "coupling". Robert Martin implied
that "coupling" was sure-shot metric that by itself would guide
decisions. But if the coupling is only in the mind rather than in code,
then it loses that status.


>
> That is, unless, the copied parts have absolutely no need to be in sync
> with the the originals.


We don't know for sure either way up-front. They may need syncing in
the future or they may not. It is a matter of *probability*, something
that Robert failed to adaquately address. This is why such "mental
coupling" tells us almost nothing about such a decision.


> For example, if I copy'n'paste a routine from
> a totally separate program as a form of code reuse, that's fine.
>
> But creating identical bits of source that are actually logically coupled
> is a horrible bad idea. One of the biggest problems developers wrestle
> with is the "synchronization problem", and it occurs any time you have
> two (or more) things that need to be kept in sync.  A simple example is
> source and comments.  They need to be kept in sync, or you end up with
> comments that are lies or half-truths.
>
> It is far better practice to factor out common functionality.  Ideally,
> you never want duplicate code, ever!
>


Note that I was not promoting copy-and-paste above. I was only
exploring it's relationship to Robert's view of "coupling".

-T-

.