From: Dan Doel <djd15@...>
Date: 2004-05-02T06:43:25+09:00
Subject: Re: Why no Proc##[]=() ? Why no Proc##replace() ?

I'm not sure what your proposal means.

If x is a Proc object, then

  x[arg1, arg2, ...]

Means to call the code stored by the Proc with the specified arguments.

What would

  x[arg1, arg2, ...] = val1, ...

Mean? In your example, we don't appear to be doing any actual assigning.
We're just moving an argument to the proc out of the []. So the following
would be equivalent:

  x[a, b, c]
  x[a, b] = c

I'm not sure why you would want to do that. Also, Proc objects are simply
wrappers around some code, so I see only two ways that x[*args] = b would
make any sense semantically:

  1) x[*args] returns some assignable value. But Ruby doesn't allow overriding
     of assignment, so that point is moot.
  2) x[*args] = c makes x contain new code somehow. But that doesn't make any
     sense either, really.

Also, what would Proc#replace do? Replace the code to be executed? You can
just make a new Proc if you want to do that. The only reason that #replace
could be different is if it kept the original binding, which means that you
could make a proc in one scope that creates variables in a completely
different scope, which would probably be impossible to compile, among other
things.

Could you explain some more?

- Dan