class NilClass
The class of the singleton object nil.
Several of its methods act as operators:
Others act as converters, carrying the concept of nullity to other classes:
While nil doesn’t have an explicitly defined to_hash method, it can be used in ** unpacking, not adding any keyword arguments.
Another method provides inspection:
Finally, there is this query method:
Public Instance Methods
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static VALUE
false_and(VALUE obj, VALUE obj2)
{
return Qfalse;
}
Returns false:
false & true # => false false & Object.new # => false
Argument object is evaluated:
false & raise # Raises RuntimeError.
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#define case_equal rb_equal
Returns true or false.
Like Object#==, if other is an instance of Object (and not an instance of one of its many subclasses).
This method is commonly overridden by those subclasses, to provide meaningful semantics in case statements.
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static VALUE
nil_match(VALUE obj1, VALUE obj2)
{
return Qnil;
}
Returns nil.
This method makes it useful to write:
while gets =~ /re/ # ... end
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#define false_xor true_and
Returns false if object is nil or false, true otherwise:
nil ^ nil # => false nil ^ false # => false nil ^ Object.new # => true
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#define false_or true_and
Returns false if object is nil or false, true otherwise:
nil | nil # => false nil | false # => false nil | Object.new # => true
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static VALUE
nil_inspect(VALUE obj)
{
return rb_usascii_str_new2("nil");
}
Returns string 'nil':
nil.inspect # => "nil"
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static VALUE
rb_true(VALUE obj)
{
return Qtrue;
}
Returns true. For all other objects, method nil? returns false.
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# File nilclass.rb, line 12 def rationalize(eps = nil) 0r end
Returns zero as a Rational:
nil.rationalize # => (0/1)
Argument eps is ignored.
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static VALUE
nil_to_a(VALUE obj)
{
return rb_ary_new2(0);
}
Returns an empty Array.
nil.to_a # => []
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# File nilclass.rb, line 24 def to_c 0i end
Returns zero as a Complex:
nil.to_c # => (0+0i)
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# File nilclass.rb, line 48 def to_f return 0.0 end
Always returns zero.
nil.to_f #=> 0.0
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static VALUE
nil_to_h(VALUE obj)
{
return rb_hash_new();
}
Returns an empty Hash.
nil.to_h #=> {}
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# File nilclass.rb, line 36 def to_i return 0 end
Always returns zero.
nil.to_i #=> 0
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# File nilclass.rb, line 60 def to_r 0r end
Returns zero as a Rational:
nil.to_r # => (0/1)
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VALUE
rb_nil_to_s(VALUE obj)
{
return rb_cNilClass_to_s;
}
Returns an empty String:
nil.to_s # => ""