From: gwtmp01@...
Date: 2005-10-28T23:03:01+09:00
Subject: Re: Argument Passing Syntax


On Oct 28, 2005, at 5:24 AM, Sean O'Halpin wrote:
> On 10/27/05, gwtmp01@mac.com <gwtmp01@mac.com> wrote:
>
>> Why are arguments to the '[]' method parsed differently
>> than a standard method?
>>
>
> Because () and [] are parsed differently. [] is primarily an array
> reference (aref).

But *why* are they parsed differently?  Just "because"?

For example, the common technique of aliasing :[] to :new means you
can't expect to have ruby parse a trailing hash in the argument list
when the method is called via :[] but you can when called via :new.

I understand that the :[] method syntax has a different evolutionary
path than the standard method syntax but is that the only reason that
the arguments are parsed differently?

> You can't pass blocks either in 1.8. In 1.9 you will be able to do  
> this:
> o[1,2,3] { |x| p x }  # this causes syntax error in 1.8 but works  
> in 1.9

Makes sense.  I vote to extend the change to allow:

o[1,2,3,:key => val]

Note, you can already have an implicit literal hash, you just can't  
precede
it with other arguments.

o[:key => val]     # OK now.
o[1,2,3]           # OK now.
o[1,2,3,:key=>val] # bad now.


Gary Wright