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Shandy Nantz

2007-Oct-09 20:03 UTC

nil? and blank?

I''ve heard this question asked before but I couldn''t find the
appropriate responces that I was looking for, but what is the difference
between Object.nil? and Object.blank? Is it how one handles white and
newline characters? To me they almost seem the same but I imagine there
has to be some differences. Thanks,

-S
-- 
Posted via http://www.ruby-forum.com/.

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Rob Bevan

2007-Oct-09 20:20 UTC

head link

Re: nil? and blank?

An object is blank if it''s nil, empty, or a whitespace string. If
it''s
nil, it''s nil.

On 10/9/07, Shandy Nantz
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:>
> I''ve heard this question asked before but I couldn''t find
the
> appropriate responces that I was looking for, but what is the difference
> between Object.nil? and Object.blank? Is it how one handles white and
> newline characters? To me they almost seem the same but I imagine there
> has to be some differences. Thanks,
>
> -S
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>
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Rob Biedenharn

2007-Oct-09 20:48 UTC

head link

Re: nil? and blank?

On Oct 9, 2007, at 4:03 PM, Shandy Nantz wrote:> I''ve heard this question asked before but I couldn''t find
the
> appropriate responces that I was looking for, but what is the  
> difference
> between Object.nil? and Object.blank? Is it how one handles white and
> newline characters? To me they almost seem the same but I imagine  
> there
> has to be some differences. Thanks,
>
> -S
Use the Source...
(vendor/rails/activesupport/lib/active_support/core_ext/blank.rb)

class Object #:nodoc:
   # "", "   ", nil, [], and {} are blank
   def blank?
     if respond_to?(:empty?) && respond_to?(:strip)
       empty? or strip.empty?
     elsif respond_to?(:empty?)
       empty?
     else
       !self
     end
   end
end

class NilClass #:nodoc:
   def blank?
     true
   end
end

class FalseClass #:nodoc:
   def blank?
     true
   end
end

class TrueClass #:nodoc:
   def blank?
     false
   end
end

class Array #:nodoc:
   alias_method :blank?, :empty?
end

class Hash #:nodoc:
   alias_method :blank?, :empty?
end

class String #:nodoc:
   def blank?
     empty? || strip.empty?
   end
end

class Numeric #:nodoc:
   def blank?
     false
   end
end

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org
+1 513-295-4739
Skype:	rob.biedenharn



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Shai Rosenfeld

2007-Oct-10 12:27 UTC

head link

Re: nil? and blank?

blank is:

""
"   "
nil
[]
{}
false

any of the above applied with .blank? will return true.

"".blank? # returns true
[].blank? # returns true
{""=>""}.blank? # returns false
{}.blank? # returns true
-- 
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Shandy Nantz

2007-Oct-10 13:27 UTC

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Re: nil? and blank?

Thanks all, that helps out a lot.
-- 
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Greg Willits

2007-Nov-03 05:22 UTC

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Re: nil? and blank?

> Use the Source...
> (vendor/rails/activesupport/lib/active_support/core_ext/blank.rb)
I''d like to have a .blank? for Time and date where 0000-00-00 00:00:00 
etc is considered blank.

Where''s the right place w/in a Rails project to add an extension to 
Ruby''s classes to accomplish that?

-- gw

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Rob Biedenharn

2007-Nov-03 12:35 UTC

head link

Re: nil? and blank?

On Nov 3, 2007, at 1:22 AM, Greg Willits wrote:>> Use the Source...
>> (vendor/rails/activesupport/lib/active_support/core_ext/blank.rb)
>
> I''d like to have a .blank? for Time and date where 0000-00-00
00:00:00
> etc is considered blank.
>
> Where''s the right place w/in a Rails project to add an extension
to
> Ruby''s classes to accomplish that?
>
> -- gw

Well, for my projects, I''ve started putting these kinds of things into
a file in:

RAILS_ROOT/lib/ext/some_class_or_behavior_name.rb

and I require them in my config/environment.rb like this:

Dir[File.join(RAILS_ROOT, ''lib'', ''ext'',
''*.rb'')].each do |f|
   base = File.basename(f, ''.rb'')
   require "ext/#{base}"
end

One project, for example, has files:
active_record_compare.rb
array.rb
enumerable.rb
file.rb
integer.rb
nil_class.rb
range.rb
string.rb
web_agent.rb


And my nil_class.rb contains:
class NilClass
   # Allowing a chain like: value.nonblank? || ''default value''
   def nonblank?
     self
   end
   # so it plays nicely with Numeric#nonzero?
   def nonzero?
     self
   end
end


That should give you some ideas.

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org


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Greg Willits

2007-Nov-03 18:00 UTC

head link

Re: nil? and blank?

On Nov 3, 2007, at 5:35 AM, Rob Biedenharn wrote:> On Nov 3, 2007, at 1:22 AM, Greg Willits wrote:
>>> Use the Source...
>>> (vendor/rails/activesupport/lib/active_support/core_ext/blank.rb)
>>
>> I''d like to have a .blank? for Time and date where 0000-00-00
>> 00:00:00
>> etc is considered blank.
>>
>> Where''s the right place w/in a Rails project to add an
extension to
>> Ruby''s classes to accomplish that?
>
>
> Well, for my projects, I''ve started putting these kinds of things
into
> a file in:
> RAILS_ROOT/lib/ext/some_class_or_behavior_name.rb
> and I require them in my config/environment.rb like this:

Makes sense. Thanks.

-- gw



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Rails - Oct 2007 - nil? and blank?

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