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Class: NilClass

Relationships & Source Files
Inherits: Object
Defined in: object.c,
complex.c,
nilclass.rb,
object.c,
rational.c

Overview

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:

Another method provides inspection:

Finally, there is this query method:

Instance Attribute Summary

Instance Method Summary

Instance Attribute Details

#nil?Boolean (readonly)

Returns true. For all other objects, method nil? returns false.

[ GitHub ]

  
# File 'object.c', line 1640

static VALUE
rb_true(VALUE obj)
{
    return Qtrue;
}

Instance Method Details

#&(object) ⇒ false #&(object) ⇒ false

Returns false:

false & true       # => false
false & Object.new # => false

Argument object is evaluated:

false & raise # Raises RuntimeError.
[ GitHub ]

  
# File 'object.c', line 1595

static VALUE
false_and(VALUE obj, VALUE obj2)
{
    return Qfalse;
}

#===

[ GitHub ]

#=~(object) ⇒ nil

Returns nil.

This method makes it useful to write:

while gets =~ /re/
  # ...
end
[ GitHub ]

  
# File 'object.c', line 1450

static VALUE
nil_match(VALUE obj1, VALUE obj2)
{
    return Qnil;
}

#^

[ GitHub ]

#inspect ⇒ 'nil'

Returns string 'nil':

nil.inspect # => "nil"
[ GitHub ]

  
# File 'object.c', line 1430

static VALUE
nil_inspect(VALUE obj)
{
    return rb_usascii_str_new2("nil");
}

#rationalize(eps = nil) ⇒ 1

Returns zero as a ::Rational:

nil.rationalize # => (0/1)

Argument eps is ignored.

[ GitHub ]

  
# File 'rational.c', line 2131

static VALUE
nilclass_rationalize(int argc, VALUE *argv, VALUE self)
{
    rb_check_arity(argc, 0, 1);
    return nilclass_to_r(self);
}

#to_aArray

Returns an empty ::Array.

nil.to_a # => []
[ GitHub ]

  
# File 'object.c', line 1396

static VALUE
nil_to_a(VALUE obj)
{
    return rb_ary_new2(0);
}

#to_c ⇒ (0+0i)

Returns zero as a ::Complex:

nil.to_c # => (0+0i)
[ GitHub ]

  
# File 'complex.c', line 1937

static VALUE
nilclass_to_c(VALUE self)
{
    return rb_complex_new1(INT2FIX(0));
}

#to_f0.0

Always returns zero.

nil.to_f   #=> 0.0
[ GitHub ]

  
# File 'nilclass.rb', line 22

def to_f
  return 0.0
end

#to_h ⇒ {}

Returns an empty ::Hash.

nil.to_h   #=> {}
[ GitHub ]

  
# File 'object.c', line 1414

static VALUE
nil_to_h(VALUE obj)
{
    return rb_hash_new();
}

#to_i0

Always returns zero.

nil.to_i   #=> 0
[ GitHub ]

  
# File 'nilclass.rb', line 10

def to_i
  return 0
end

#to_r1

Returns zero as a ::Rational:

nil.to_r # => (0/1)
[ GitHub ]

  
# File 'rational.c', line 2114

static VALUE
nilclass_to_r(VALUE self)
{
    return rb_rational_new1(INT2FIX(0));
}

#to_s ⇒ ''

Returns an empty ::String:

nil.to_s # => ""
[ GitHub ]

  
# File 'object.c', line 1378

VALUE
rb_nil_to_s(VALUE obj)
{
    return rb_cNilClass_to_s;
}

#|

[ GitHub ]