From: Trans <transfire@...>
Date: 2006-08-18T05:45:06+09:00
Subject: Re: Multiple arguments for Hash#delete


Daniel Schierbeck wrote:
> Trans wrote:
> >> If #delete should be altered, why should #[] and #[]= ?
> >
> > You may have a point. Though it doesn't matter as much becuase it's
> > much less often the anyone depends on the return value of []=. ie. we
> > just use it to set values.
>
> I only added #[]= because, with Facets, you can do this (as you of
> course know)
>
>    hsh[:a, :b, :c] = 1, 2, 3
>
> which matches nicely with
>
>    a, b, c = hsh[:a, :b, :c]
>
> My point is that #delete is also a retrieval method, in the sense that
> it returns the value it has removed from the hash. Therefore it is
> natural for it to have the same functionality as #[], which in turn
> means that we have to alter #delete in Facets.
>
>    a, b, c = hsh.delete(:a, :b, :c)
>
> Simple and elegant.

Yea, I know what you mean. Believe me I went through the same viewpoint
when working on this for Array. Unfortunately the simplicity and
elegance start to crumble when:

  a = hsh.delete(*array)

Which leads to things like:

  a = [hsh.delete(*array)].flatten

or

  a = hsh.delete(*array)
  case a
  when Array
    ...
  else
    ...
  end

Which means you'll just opt to use #delete_at anyway.

> > But to be very percise it should probably be
> > changed to match Array's. Consider that Array's []= method does take
> > multuiple parameters related to slicing. Facets' deals with that by
> > allowing it to also take an  Array parameter:
> >
> >   a = []
> >   a[[1,2,3]] = :a, :b, :c
> >   a #=> [ :a, :b, :c ]
> >
> > Hash's can be made to do the same. What do you think?
>
> Actually, I don't like that solution very much. It doesn't seem very
> elegant.

Yes, but sometime simplicity and elegance have to give way to
practicality. I do hope Matz will take some time to address the
"duckability" between Array and Hash for 2.0, though. That would
certainly go a long way toward simplicity and elegance more than
anything.

T.