Empty nil

Jun 16, 2007

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Recently I have started to add one extension to Rubys NilClass, when creating new Rails application. It is empty? method. For me is obvious that result nil.empty? should be true. Adding such method allow to write:

if some_var_which_can_be_nil.empty?
   #code to handle nil/empty case
end

Instead of

if some_var_which_can_be_nil.nil? || some_var_which_can_be_nil.empty?
   #code to handle nil/empty case
end

Using first example without extending NilClass will result with NoMethod exception, when variable will be nil:

irb(main):001:0> nil.empty?
NoMethodError: undefined method `empty?' for nil:NilClass
        from (irb):1

If in some case I would need to distinguish between nil and empty cases it can be done with check against nil in code handling nil/empty case. And of course NilClass extension is trivial:

class NilClass
  def empty?
    true
  end
end

Result? More compact and clean code, which is good ;-)

Comments

3 responses to “Empty nil”

Robert Horvath

July 31, 2007

if some_var_which_can_be_nil.blank?
#code to handle nil/empty case
end

instead of

if some_var_which_can_be_nil.nil? || some_var_which_can_be_nil.empty?
#code to handle nil/empty case
end
NetManiac

August 16, 2007

It is always time to learn ;))

NetManiac

November 5, 2007

One word more – nil.blank? is Rails extension to Ruby!

In pure Ruby:

$ irb
irb(main):001:0> nil.blank?
NoMethodError: undefined method `blank?' for nil:NilClass
 from (irb):1
 from :0
irb(main):002:0>

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Empty nil

Comments

3 responses to “Empty nil”

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