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Reynard

2007-Jul-18 14:52 UTC

extending nil methods

has anyone done something like this?

class NilClass
  def empty?; true; end
  def strip; nil; end
  def [](s); nil; end
end

which is nice so that you can do this without throwing exception:
if !params[:something].empty?
if !params[:something][:else].strip.empty?

as opposed to this:
if params[:something] && !params[:something].empty?
if params[:something] && params[:something][:else] && !
params[:something][:else].strip.empty?

It seems to work fine for me so far. I''m just wondering what''s
the
negative effect of doing that? If not then shouldn''t we be doing
this :) ?

- reynard


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Reynard

2007-Jul-18 15:31 UTC

head link

extending nil methods

it seems my previous post didn''t get through for some reason, so sorry
if this is duplicated.

has anyone done something like this?

class NilClass
  def empty?; true; end
  def strip; nil; end
  def [](s); nil; end
end

so you can do this without throwing exception
if !params[:s].empty?
if !params[:s][:e].strip.empty?

as opposed to:
if params[:s] && !params[:s].empty?
if params[:s] && params[:s][:e] && !params[:s][:e].strip.empty?


I''m just wondering is there negative effects of doing this? if not
then shouldn''t we be doing this. it makes your code look a lot nicer
doesn''t it? :)

- reynard


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Reynard Hilman

2007-Jul-18 16:04 UTC

head link

Re: extending nil methods

hmm is google group broken? my post never seems to get through. did anyone
get this message?

On 7/18/07, Reynard <reynardmh-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:>
> it seems my previous post didn''t get through for some reason, so
sorry
> if this is duplicated.
>
> has anyone done something like this?
>
> class NilClass
>   def empty?; true; end
>   def strip; nil; end
>   def [](s); nil; end
> end
>
> so you can do this without throwing exception
> if !params[:s].empty?
> if !params[:s][:e].strip.empty?
>
> as opposed to:
> if params[:s] && !params[:s].empty?
> if params[:s] && params[:s][:e] &&
!params[:s][:e].strip.empty?
>
>
> I''m just wondering is there negative effects of doing this? if not
> then shouldn''t we be doing this. it makes your code look a lot
nicer
> doesn''t it? :)
>
> - reynard
>
>
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Florian Gilcher

2007-Jul-19 08:57 UTC

head link

Re: extending nil methods

Reynard wrote:> has anyone done something like this?
> 
> class NilClass
>   def empty?; true; end
>   def strip; nil; end
>   def [](s); nil; end
> end
> 
> which is nice so that you can do this without throwing exception:
> if !params[:something].empty?
> if !params[:something][:else].strip.empty?
> 
> as opposed to this:
> if params[:something] && !params[:something].empty?
> if params[:something] && params[:something][:else] && !
> params[:something][:else].strip.empty?
> 
> It seems to work fine for me so far. I''m just wondering
what''s the
> negative effect of doing that? If not then shouldn''t we be doing
> this :) ?
> 
> - reynard
You disable errors that make perfect sense. The problem is that you 
really get into a world of pain if you do not expect any nil values is 
you Hash (or the expected Hash to be nil instead). This is when you want 
to see those errors.

I see your problem with if params[:something][:else], but your first 
example is already solved by such a technique: Rails has #blank? which 
is defined on nil.

if params[:something] && !params[:something].empty?
=>
unless params[:something].blank?



-- 
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Matthew Rudy

2007-Jul-19 09:04 UTC

head link

Re: extending nil methods

I agree,
blank? is the way.

otherwise I suggest;

class NilClass
  def method_missing(method_name, *args)
    return true
  end
end

Florian Gilcher wrote:> Reynard wrote:
>> has anyone done something like this?
>> 
>> class NilClass
>>   def empty?; true; end
>>   def strip; nil; end
>>   def [](s); nil; end
>> end
-- 
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Reynard

2007-Jul-19 15:54 UTC

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Re: extending nil methods

ah I knew there must be a better way. It''s strange that I cannot find
blank? in the ruby or rails api documentation.
Thanks a lot,
- reynard

On Jul 19, 5:04 am, Matthew Rudy
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:> I agree,
> blank? is the way.
>
> otherwise I suggest;
>
> class NilClass
>   def method_missing(method_name, *args)
>     return true
>   end
> end
>
> Florian Gilcher wrote:
> > Reynard wrote:
> >> has anyone done something like this?
>
> >> class NilClass
> >>   def empty?; true; end
> >>   def strip; nil; end
> >>   def [](s); nil; end
> >> end
>
> --
> Posted viahttp://www.ruby-forum.com/.

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