Rails - Jun 2006 - attributes and views

Hello,

 I always have the same kind of design problem, which I am not sure how 
to solve correctly:

 - say I have a variable, "status", which I want to calculate once in
my
controller, and access a couple of times in my view
 - "status" variable initialization could happen in a subclass, 
overriding the regular method for that

 What I do now is using an instance variable @status, which is set in a 
dedicated method ''set_status'', which can be overriden in
subclasses if
needed. I then can access @status from methods of my controller or from 
the view. But is that the best way? I tried to find something with 
attributes, but I''m not sure...

 What do you think?

-- 
----------------------------------------------------------------------
Yannick Majoros http://www.inma.ucl.ac.be/~majoros
Informaticien UCL/INMA-MEMA
4, avenue G. Lema?tre
B-1348 Louvain-la-Neuve
Tel: +32-10-47.80.10
Fax: +32-10-47.21.80
----------------------------------------------------------------------
Mon calendrier en ligne : http://www.inma.ucl.ac.be/~majoros/calendar
Accents bizarres ? http://www.inma.ucl.ac.be/~majoros/email.html
----------------------------------------------------------------------



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Hello Yannick.

I don''t believe a model''s status should be calculated in the
controller.

What if you want to use the model outside of a web app someday? Are you
going to duplicate the code somewhere else and maintain that code in
parallel forever?

It would seem to me that you''d trying for optimization here, avoiding
recalculating status each time it''s used. Is the calculation *very*
expensive? If not, don''t optimize it until it hurts!

If it is expensive, you could easily write something like this:

in model:

   def status
     return @the_status unless @the_status.nil? # return cached status
     @the_status = # perform expensive status calculation here
   end

--  
-- Tom Mornini

On Jun 16, 2006, at 3:53 AM, Yannick Majoros wrote:
> Hello,
>
> I always have the same kind of design problem, which I am not sure  
> how to solve correctly:
>
> - say I have a variable, "status", which I want to calculate once
> in my controller, and access a couple of times in my view
> - "status" variable initialization could happen in a subclass,  
> overriding the regular method for that
>
> What I do now is using an instance variable @status, which is set  
> in a dedicated method ''set_status'', which can be
overriden in
> subclasses if needed. I then can access @status from methods of my  
> controller or from the view. But is that the best way? I tried to  
> find something with attributes, but I''m not sure...
>
> What do you think?
>
> -- 
> ----------------------------------------------------------------------
> Yannick Majoros http://www.inma.ucl.ac.be/~majoros
> Informaticien UCL/INMA-MEMA
> 4, avenue G. Lema?tre
> B-1348 Louvain-la-Neuve
> Tel: +32-10-47.80.10
> Fax: +32-10-47.21.80
> ----------------------------------------------------------------------
> Mon calendrier en ligne : http://www.inma.ucl.ac.be/~majoros/calendar
> Accents bizarres ? http://www.inma.ucl.ac.be/~majoros/email.html
> ----------------------------------------------------------------------
>
>
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
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