From: Robert Klemme <bob.news@...>
Date: 2004-06-06T21:08:40+09:00
Subject: Re: How to ducktype a Hash?


"gabriele renzi" <surrender_it@remove.yahoo.it> schrieb im Newsbeitrag
news:t116c09e5964u321qbahvkdorlilg7j1hp@4ax.com...
> il Sun, 6 Jun 2004 18:52:44 +0900, Jeff Mitchell
> <quixoticsycophant@yahoo.com> ha scritto::
>
>
> >This is the fault of PStore or of the lack of agreed-upon semantics
> >for classes with hash-like behavior.  There should be a standard list
> >which includes the definition of such behavior.  Here, I'll start the
> >list now:
> >
> > hash-like:  #fetch, #store
> >array-like:  #at, #store
> >
> >Any others?  How about tree-like?
> >
> >I want this list to be part of the ruby standard -- clearly
> >documented so that implementers know they should define #fetch
> >and #store for the hash-like classes they write.  [] should
> >be viewed as convenience only.
>
> I may be wrong but what you're asking has been throw out many times.
> It would be wonderful to have stuff like this for everything,
> toghether with a possible mix-in.
> We have, actually, many 'default quacks' like :read and :write for
> IOs, :each for enumerables,  and so on.
>
>  Maybe adding some more mix-ins would be fine for many people's need
> (say, if a Map mixin existed, we could have it rely on fetch(),keys()
> and store() to provide all the other methods). This way hash-like
> stuff like PStore, will just need to include the mix-in and Sean could
> just check for kind_of? Map if he feels the need for this.
>
> Oh, and can I ask for an Input and Output mixin, while I'm at it ? :)

Just a note: excessive need for type checks like these may be a hint for
weak OO design.

Kind regards

    robert