From: Joel VanderWerf <vjoel@...>
Date: 2006-11-30T16:16:46+09:00
Subject: Re: Wrong results using named arguments

ara.t.howard@noaa.gov wrote:
> On Thu, 30 Nov 2006, Jason  Vogel wrote:
> 
>> Okay, I have a couple of questions. If I use the Hash approach,
>>
>> - How do I handle argument default values?
> 
>   def the_method opts = { :arg => 'default value', :another_arg => 
> 'default value too' }

Not really, at least in 1.8. That sets the default for _opts_, not for 
each of the named args.

def the_method opts = { :arg => 'default value', :another_arg => 
'default value too' }
   p opts
end

the_method :arg => "qwe"  # ==> {:arg=>"qwe"}

Note that the hash doesn't retain the default value for :another_arg.

Has this changed in 1.9? Is there a way to set the defaults for keyword 
args?

...
>> - Is there a way to enumerate the valid choices for values (e.g. colors
>> = [red,white,blue])
> 
>   def the_method opts = { :a => %w( a b c ).first, :b => %w( d e f 
> ).first }

You know this gets evaluated every time you call the_method, right?

def m opts = { :foo => (puts "called m") }; end
m; m

output:

called m
called m

Anyway, this serves no purpose beyond documentation (it doesn't 
validate). Why not just put this info into the rdoc for the method?

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407