From: Dossy <dossy@...>
Date: 2002-06-14T03:52:05+09:00
Subject: Re: procs and blocks

On 2002.06.14, Evan Martin <martine@cs.washington.edu> wrote:
> On Thu, Jun 13, 2002 at 08:20:11PM +0900, Dirk Detering wrote:
> > This seems to indicate me that 'named parameters'
> > are missing, which are possible in Python
> > (and do attract me)?
> > 
> > With that the last line would read:
> > err (b=a)  
> > 
> > Ok, in Ruby there should be an alternative syntax,
> > as this one causes another result (and is supposed to).
> 
> You can simulate named parameters with a hash:
> 
> def foo(params)
>   p params[:rar]
>   p params[:blah]
> end
> 
> foo(:blah => "hello", :rar => "meow")
> 
> but yes, I agree Python is nicer in this respect.

Does Ruby really automagically coerce that parameter list into
a Hash?

PoLS for me would have been to write:

    foo( { :blah => "hello", :rar => "meow" } )

The shorthand you wrote where the parameters automagically
get coerced into a Hash is definitely the desirable behavior,
but at first glance I'd have to ask: "what kind of Object will
the #foo method be receiving?" and guess ...

(I guess I can take out all those unecessary {}'s in my code
now ... I probably should have tried without to see if it'd
work, but then I'd be surprised if it did ...)

What about this, though:

    foo :blah => "hello", :rar => "meow"

Does that work?  Yes, it does, cool.  But:

    foo { :blah => "hello", :rar => "meow" }

That doesn't work.  (I can see why: am I passing a block, or a
Hash object?)  This is the error I get (on Ruby 1.6.7):

    irb(main):020:0> foo { :blah => "hello", :rar => "meow" }
    SyntaxError: compile error
    (irb):20: parse error
    foo { :blah => "hello", :rar => "meow" }
                  ^
            from (irb):20

So, is best-practice to let the Ruby parser do the magic and
create a new Hash array without using the {} notation?

-- Dossy

-- 
Dossy Shiobara                       mail: dossy@panoptic.com 
Panoptic Computer Network             web: http://www.panoptic.com/ 
  "He realized the fastest way to change is to laugh at your own
    folly -- then you can let go and quickly move on." (p. 70)