From: hemant <gethemant@...>
Date: 2007-07-13T18:59:22+09:00
Subject: Re: Help with passing a callback method

On 7/13/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> 2007/7/13, Micke Lax <mickelax@yahoo.se>:
> > I am trying to do the following. I can't get it to work, don't know if
> > it even is possible but it would be nice. If it is not possible to do it
> > the way I try here is there any other good approach?
> >
> > My reason to use a callback is to keep the code size down and avoid
> > duplicate code. in one case I would use create_xml_str and in the other
> > case create_h_str
> >
> > I have cut out a lot of code to keep the size down, tell me if you need
> > to see more.
>
> I'd rather here where you want to put the callback and what it is
> supposed to do.
>
> The generic answer would be: use a block as callback. You can even
> store it somewhere or pass it on:
>
> def foo(&b)
>   puts "calling"
>   b.call
> end
>
> def bar(&x)
>   puts "delegating"
>   foo(&x)
> end
>
> bar do
>   puts "block"
> end

Damn you Robert. :)


>
> > ###--------------------------------------------------------------------
> > ### header_data.rb
> > ###--------------------------------------------------------------------
> > class Header_Data
> >   def create_xml_str
> >   # returns a xml-formated string
> >   end
> >
> >   def create_h_str
> >   # returns a h-formated string
> >   end
> >
> > end
> >
> >
> > ###--------------------------------------------------------------------
> > ### header_data_array.rb
> > ###--------------------------------------------------------------------
> > /.../
> > class Header_Data_Array
> >
> > def interpret_layout(t, callback)
> >     result = String.new
> >     case
> >     when (t.match(/empty/))
> >       result = "\n\n"
> >
> >     when (t.match(/^\d{1,4}/))
> >       a = @data_array[t.to_i]
> >       # here a tries to call the callback (crash...)
> >       a.callback.call()
> >
> >     when (t.match(/[A-Z]*/))
> >       result =  create_subtitle_str(t)
> >
> >     end
> >     return result
> >   end
> >
> >
> >
> >   def create_file(file_name, layout)
> >     # get the callback and pass it in the method call
> >     function = Header_Data.new.method(:create_xml_string)
> >     layout   = layout.map{|l| interpret_layout(l, function)}
> >
> >   end
> > /.../
>
> Kind regards
>
> robert
>
>


-- 
gnufied
-----------
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were at every doorstep, and every path was its tributary.
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