From: James Edward Gray II <james@...>
Date: 2005-12-09T00:32:27+09:00
Subject: Re: A small query

On Dec 8, 2005, at 6:37 AM, Robert Klemme wrote:

> Srinivas Jonnalagadda wrote:
>> Dear all,
>>
>> Object Pascal (at least as provided by Delphi) has a facility to send
>> a sequence of messages to the same receiver, using a construct called
>> 'with'. If 'obj' is an object with callable methods 'meth1', 'meth2'
>> and 'meth3', it is possible to write:
>>
>>    with obj do
>>      meth1();
>>      meth2(param);
>>      meth3(param1, param2)
>>    end
>>
>> Can a similar thing be accomplished in Ruby?
>
> obj.instance_eval do
>   meth1
>   meth2(param)
>   meth3(param1, param2)
> end

So, we can rename that to create what you asked for:

class Object
   alias_method :with, :instance_eval
end

Then your code would run.

Here's another idea:

[ [:meth1],
   [:meth2, param],
   [:meth3, param1, param2] ].each do |call_details|
   obj.send(*call_details)
end

Or we could switch that to a Hash, which probably makes more sense here:

{ :meth1 => [],
   :meth2 => [param],
   :meth3 => [param1, param2] }.each do |meth, params|
   obj.send(meth, *params)
end

We can wrap that:

class Object
   def with( hash_of_calls )
     hash_of_calls.each { |meth, params| obj.send(meth, *params) }
   end
end

And take advantage of Ruby's auto-hashing parameter syntax:

obj.with :meth1 => [],
          :meth2 => [param],
          :meth3 => [param1, param2]

Maybe that will give you some fresh ideas.

James Edward Gray II