Class: Cygnet::NullObject

Inherits:
Object
  • Object
show all
Defined in:
lib/cygnet/null_object.rb

Overview

NullObject implements the widely-known NullObject pattern, where an instance responds to any method called on it by returning another NullObject, allowing arbitrary chaining of method calls without the risk of a NoMethodError.

As an exception, NullObject can be cast to other types, taking a neutral value of that type; it is cast to the empty string, 0, 0.0, the empty Array and Hash, etc.

Additionally, it identifies positively as #nil? and #blank? for compatability with common checks on “neutral” or “empty” values by imitating the behaviour of nil.

Instance Method Summary collapse

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(*_args, &_block) ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 14

def method_missing(*_args, &_block)
  self
end

Instance Method Details

#! ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 30

def !
  true
end

#blank? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/cygnet/null_object.rb', line 26

def blank?
  nil?
end

#nil? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/cygnet/null_object.rb', line 22

def nil?
  true
end

#respond_to_missing?(_method_name, _include_private = true) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/cygnet/null_object.rb', line 18

def respond_to_missing?(_method_name, _include_private = true)
  true
end

#to_a ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 46

def to_a
  []
end

#to_ary ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 50

def to_ary
  []
end

#to_c ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 62

def to_c
  Complex(0)
end

#to_f ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 42

def to_f
  0.0
end

#to_h ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 54

def to_h
  {}
end

#to_hash ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 58

def to_hash
  {}
end

#to_i ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 38

def to_i
  0
end

#to_r ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 66

def to_r
  Rational(0)
end

#to_s ⇒ Object 



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# File 'lib/cygnet/null_object.rb', line 34

def to_s
  ''
end