From: Robert Dober <robert.dober@...>
Date: 2007-01-18T22:34:04+09:00
Subject: Re: Hash#open! / Hash#close!

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On 1/18/07, Trans <transfire@gmail.com> wrote:
>
> <lots of interesting stuff snipped **FOR NOW**>
> T
>
>
> ps. i came across an oddity while messing with this:
>
> irb(main):019:0> q =3D {}
> =3D> {}
> irb(main):020:0> q.sort_by
> =3D> []
> irb(main):021:0> q[:a] =3D 1
> =3D> 1
> irb(main):022:0> q.sort_by
> LocalJumpError: no block given
>         from (irb):22:in `sort_by'
>         from (irb):22
>         from =03:0
> ruby 1.8.4 on debian


Hmm is it really an oddity (I have the same behavior  on 1.8.5/debian)?
An empty hash sort  just cannot apply the block to any elements, but I gues=
s
you know that ;).
Would you prefer that sort_by just checks for the presence of a block
anyway?

I gotto think a lot about the rest you have written most interesting stuff,
just some very quick thoughts
* There are structs you know ;)
* #open! could return self so that one can write h=3D{:value=3D>42}.open!
#close! should than too for symmetry.
* Would it not be better not to hide a method in case the hash has no key?
That would be a mess right? One would not know if h.size is 1 because of
h[:size]=3D1 or h=3D{:a=3D>1}.open!
* I'd like to use #open! behind the scenes with a block form like
    class Hash
       def  use_opened &blk
             open!
             blk.call(self) if blk
             close!
      end
   end
or even
    class Hash
        def in_context &blk
             open!
             instance_eval &blk
     .....

Conclusion:
  Basically it is a nice idea but maybe you really want a struct.
  I would not think it should be in the core but in an extension like facet
of course it might
  be spot on ;)


In any case that is the kind of post which make this ML so much fun and
education.

Cheers
Robert




--=20
"The best way to predict the future is to invent it."
- Alan Kay

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