From: "David A. Black" <dblack@...>
Date: 2005-10-10T11:48:56+09:00
Subject: Re: local_variable_set ?

Hi --

On Mon, 10 Oct 2005, David A. Black wrote:

> Hi --
>
> On Mon, 10 Oct 2005, Hal Fulton wrote:
>
>> No, this isn't April Fool's Day. I'm seriously wondering
>> if this has ever been considered.
>> 
>> I can only think of one place I'd use it -- to turn hashes
>> (used as named parameters) into real variables.
>> 
>> Something like:
>> 
>>  def meth(hash)
>>    bind = binding
>>    hash.each_pair {|k,v| local_variable_set(k,v,bind) }
>>    # Assuming call was:  meth(alpha: 123, beta: 234, gamma: 345)
>>    # we now can reference alpha, beta, and gamma as ordinary
>>    # variables...
>>  end
>
> I think making bindings writeable has been suggested:
>
>  binding[:alpha] = 123
>
> or whatever.
>
>> Thoughts?
>
> To me it suggests too tight a coupling between the caller and the
> method.  If you write a method that depends on being told to create a
> local variable with a particular name, you're limiting what can be
> done by way of refactoring and reimplementing the method.

Maybe not, though.  I guess the idea would be that the caller is
supposed to send those names in a hash anyway.  I think I might find
it weird, though, to see:

   def meth(hash)
     bind = binding
     hash.each_pair {|k,v| local_variable_set(k,v,bind) }
     puts alpha
     beta += 2
     if defined?(gamma)
       puts "gamma came from somewhere..."

etc., without having any visual cues (arglist or assignment) as to
where those names came from.


David

-- 
David A. Black
dblack@wobblini.net