Rails - Mar 2006 - Passing function names from string variables

This may be a more generic Ruby question, so I''m going to ask on the
Ruby
forum, but I''m trying to figure out if there is a way to pass in the
string
value of a variable as the name of a method.

For example, I would like to do something like:

  def sort_obj_by_uid(objects,@attr)
    @tmparray = Array.new
    @tmphash = Hash.new
    for object in @objects
      if ! @tmphash.has_key?(object.@attr.to_s)
        @tmphash[object.@attr.to_s] = Array.new
      end
      @tmphash[object.@attr.to_s].push(object)
    end
  end

Where the method name is the @attr value.

-- 
Leah Cunningham : d416-585-9971x692 : d416-703-5977 : m416-559-6511
Frauerpower! Co. : www.frauerpower.com : Toronto, ON Canada

Hi --

On Thu, 16 Mar 2006, Leah Cunningham wrote:
> This may be a more generic Ruby question, so I''m going to ask on
the Ruby
> forum, but I''m trying to figure out if there is a way to pass in
the string
> value of a variable as the name of a method.
>
> For example, I would like to do something like:
>
>  def sort_obj_by_uid(objects,@attr)
>    @tmparray = Array.new
>    @tmphash = Hash.new
>    for object in @objects
>      if ! @tmphash.has_key?(object.@attr.to_s)
>        @tmphash[object.@attr.to_s] = Array.new
>      end
>      @tmphash[object.@attr.to_s].push(object)
>    end
>  end
>
> Where the method name is the @attr value.
Yes: send, like this:

   object.send(@attr).to_s

If you want to send additional arguments, you put them in the second,
third... positions.


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

"Ruby for Rails" chapters now available
from Manning Early Access Program! http://www.manning.com/books/black

Very easy:

@obj.send(@attr.to_sym)

On 3/16/06, Leah Cunningham <leah@frauerpower.com>
wrote:
> This may be a more generic Ruby question, so I''m going to ask on
the Ruby
> forum, but I''m trying to figure out if there is a way to pass in
the string
> value of a variable as the name of a method.
>
> For example, I would like to do something like:
>
>   def sort_obj_by_uid(objects,@attr)
>     @tmparray = Array.new
>     @tmphash = Hash.new
>     for object in @objects
>       if ! @tmphash.has_key?(object.@attr.to_s)
>         @tmphash[object.@attr.to_s] = Array.new
>       end
>       @tmphash[object.@attr.to_s].push(object)
>     end
>   end
>
> Where the method name is the @attr value.
>
> --
> Leah Cunningham : d416-585-9971x692 : d416-703-5977 : m416-559-6511
> Frauerpower! Co. : www.frauerpower.com : Toronto, ON Canada
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

On Thu, 16 Mar 2006, dblack@wobblini.net wrote:
> Hi --
>
> On Thu, 16 Mar 2006, Leah Cunningham wrote:
>
>> This may be a more generic Ruby question, so I''m going to ask
on the Ruby
>> forum, but I''m trying to figure out if there is a way to pass
in the string
>> value of a variable as the name of a method.
>> 
>> For example, I would like to do something like:
>>
>>  def sort_obj_by_uid(objects,@attr)
>>    @tmparray = Array.new
>>    @tmphash = Hash.new
>>    for object in @objects
>>      if ! @tmphash.has_key?(object.@attr.to_s)
>>        @tmphash[object.@attr.to_s] = Array.new
>>      end
>>      @tmphash[object.@attr.to_s].push(object)
>>    end
>>  end
>> 
>> Where the method name is the @attr value.
>
> Yes: send, like this:
>
>  object.send(@attr).to_s
Whoops, I meant:

   object.send(@attr.to_s)


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

"Ruby for Rails" chapters now available
from Manning Early Access Program! http://www.manning.com/books/black