From: matz@... (Yukihiro Matsumoto)
Date: 2000-04-23T01:41:20+09:00
Subject: [ruby-talk:02568] Re: Default naming for iterator parameters

Hi,

In message "[ruby-talk:02558] Re: Default naming for iterator parameters"
    on 00/04/21, mrilu <mrilu@ale.cx> writes:

|>reading other people's code:  "where'd *that* variable come from?  hmm, not up
|>here, not over here, oh it maybe it's one of those magic parameters, where's
|>the documentation for this iterator?  well, it's coming from the object `foo',
|>so what class is `foo'?  *page page* aha, looks like it's a Bar, or maybe a
|>subclass.  well, there is no doc for Bar#iterator, but aha, the Baz mix-in
|>does have iterator!  ok, now where was I?"
|
|This could be very true. We might lose some readibility. I don't have so much
|experience of the world of Ruby iterators to be able to judge whether 
|one can associate iterators variables at once or it will cause confusion.

In addition, the parser requires all local variable names to be known
at compile time.  It treats unknown local variables as method
invocation without argument.  This behavior also frees programmer from
searching around variable declarations.

There's no way to get magic variables names at compile time in
general, because the method invocation may appear before its
definition, which is done at runtime.  I have no idea to resolve this.
Assuming it's not impossible, it may require to add awkward rules to
the syntax.

I think introducing magic variables makes your programs bit more
concise, but far more complicated.

							matz.