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Module: Comparable

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In:
Defined in: compar.c

Overview

The Comparable mixin is used by classes whose objects may be ordered. The class must define the <=> operator, which compares the receiver against another object, returning a value less than 0, 0, or a value greater than 0, depending on whether the receiver is less than, equal to, or greater than the other object. If the other object is not comparable then the <=> operator should return nil. Comparable uses <=> to implement the conventional comparison operators (#<, #<=, #==, #>=, and #>) and the method #between?.

class SizeMatters
  include Comparable
  attr :str
  def <=>(other)
    str.size <=> other.str.size
  end
  def initialize(str)
    @str = str
  end
  def inspect
    @str
  end
end

s1 = SizeMatters.new("Z")
s2 = SizeMatters.new("YY")
s3 = SizeMatters.new("XXX")
s4 = SizeMatters.new("WWWW")
s5 = SizeMatters.new("VVVVV")

s1 < s2                       #=> true
s4.between?(s1, s3)           #=> false
s4.between?(s3, s5)           #=> true
[ s3, s2, s5, s4, s1 ].sort   #=> [Z, YY, XXX, WWWW, VVVVV]

Instance Method Summary

  • #<(other) ⇒ Boolean

    Compares two objects based on the receiver's <=> method, returning true if it returns a value less than 0.

  • #<=(other) ⇒ Boolean

    Compares two objects based on the receiver's <=> method, returning true if it returns a value less than or equal to 0.

  • #==(other) ⇒ Boolean

    Compares two objects based on the receiver's <=> method, returning true if it returns 0.

  • #>(other) ⇒ Boolean

    Compares two objects based on the receiver's <=> method, returning true if it returns a value greater than 0.

  • #>=(other) ⇒ Boolean

    Compares two objects based on the receiver's <=> method, returning true if it returns a value greater than or equal to 0.

  • #between?(min, max) ⇒ Boolean

    Returns false if obj <=> min is less than zero or if anObject <=> max is greater than zero, true otherwise.

  • #clamp(min, max) ⇒ Object

    Returns min if obj <=> min is less than zero, max if obj <=> max is greater than zero and obj otherwise.

Instance Method Details

#<(other) ⇒ Boolean

Compares two objects based on the receiver's <=> method, returning true if it returns a value less than 0.

[ GitHub ]

  
# File 'compar.c', line 131

static VALUE
cmp_lt(VALUE x, VALUE y)
{
    if (cmpint(x, y) < 0) return Qtrue;
    return Qfalse;
}

#<=(other) ⇒ Boolean

Compares two objects based on the receiver's <=> method, returning true if it returns a value less than or equal to 0.

[ GitHub ]

  
# File 'compar.c', line 146

static VALUE
cmp_le(VALUE x, VALUE y)
{
    if (cmpint(x, y) <= 0) return Qtrue;
    return Qfalse;
}

#==(other) ⇒ Boolean

Compares two objects based on the receiver's <=> method, returning true if it returns 0. Also returns true if obj and other are the same object.

[ GitHub ]

  
# File 'compar.c', line 74

static VALUE
cmp_equal(VALUE x, VALUE y)
{
    VALUE c;
    if (x == y) return Qtrue;

    c = rb_exec_recursive_paired_outer(cmp_eq_recursive, x, y, y);

    if (NIL_P(c)) return Qfalse;
    if (rb_cmpint(c, x, y) == 0) return Qtrue;
    return Qfalse;
}

#>(other) ⇒ Boolean

Compares two objects based on the receiver's <=> method, returning true if it returns a value greater than 0.

[ GitHub ]

  
# File 'compar.c', line 101

static VALUE
cmp_gt(VALUE x, VALUE y)
{
    if (cmpint(x, y) > 0) return Qtrue;
    return Qfalse;
}

#>=(other) ⇒ Boolean

Compares two objects based on the receiver's <=> method, returning true if it returns a value greater than or equal to 0.

[ GitHub ]

  
# File 'compar.c', line 116

static VALUE
cmp_ge(VALUE x, VALUE y)
{
    if (cmpint(x, y) >= 0) return Qtrue;
    return Qfalse;
}

#between?(min, max) ⇒ Boolean

Returns false if obj <=> min is less than zero or if anObject <=> max is greater than zero, true otherwise.

3.between?(1, 5)               #=> true
6.between?(1, 5)               #=> false
'cat'.between?('ant', 'dog')   #=> true
'gnu'.between?('ant', 'dog')   #=> false
[ GitHub ]

  
# File 'compar.c', line 168

static VALUE
cmp_between(VALUE x, VALUE min, VALUE max)
{
    if (cmpint(x, min) < 0) return Qfalse;
    if (cmpint(x, max) > 0) return Qfalse;
    return Qtrue;
}

#clamp(min, max) ⇒ Object

Returns min if obj <=> min is less than zero, max if obj <=> max is greater than zero and obj otherwise.

12.clamp(0, 100)         #=> 12
523.clamp(0, 100)        #=> 100
-3.123.clamp(0, 100)     #=> 0

'd'.clamp('a', 'f')      #=> 'd'
'z'.clamp('a', 'f')      #=> 'f'
[ GitHub ]

  
# File 'compar.c', line 192

static VALUE
cmp_clamp(VALUE x, VALUE min, VALUE max)
{
    int c;

    if (cmpint(min, max) > 0) {
	rb_raise(rb_eArgError, "min argument must be smaller than max argument");
    }

    c = cmpint(x, min);
    if (c == 0) return x;
    if (c < 0) return min;
    c = cmpint(x, max);
    if (c > 0) return max;
    return x;
}