module Comparable
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, returning 0, or returning 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 StringSorter include Comparable attr :str def <=>(other) str.size <=> other.str.size end def initialize(str) @str = str end def inspect @str end end s1 = StringSorter.new("Z") s2 = StringSorter.new("YY") s3 = StringSorter.new("XXX") s4 = StringSorter.new("WWWW") s5 = StringSorter.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]
What’s Here¶ ↑
Module Comparable provides these methods, all of which use method <=>
:
-
#<: Returns whether
self
is less than the given object. -
#<=: Returns whether
self
is less than or equal to the given object. -
==
: Returns whetherself
is equal to the given object. -
#>: Returns whether
self
is greater than the given object. -
#>=: Returns whether
self
is greater than or equal to the given object. -
between?
: Returnstrue
ifself
is between two given objects. -
clamp
: For given objectsmin
andmax
, or range(min..max)
, returns:-
min
if(self <=> min) < 0
. -
max
if(self <=> max) > 0
. -
self
otherwise.
-
Public Instance Methods
Compares two objects based on the receiver’s <=>
method, returning true if it returns a value less than 0.
static VALUE cmp_lt(VALUE x, VALUE y) { return RBOOL(cmpint(x, y) < 0); }
Compares two objects based on the receiver’s <=>
method, returning true if it returns a value less than or equal to 0.
static VALUE cmp_le(VALUE x, VALUE y) { return RBOOL(cmpint(x, y) <= 0); }
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.
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; return RBOOL(rb_cmpint(c, x, y) == 0); }
Compares two objects based on the receiver’s <=>
method, returning true if it returns a value greater than 0.
static VALUE cmp_gt(VALUE x, VALUE y) { return RBOOL(cmpint(x, y) > 0); }
Compares two objects based on the receiver’s <=>
method, returning true if it returns a value greater than or equal to 0.
static VALUE cmp_ge(VALUE x, VALUE y) { return RBOOL(cmpint(x, y) >= 0); }
Returns false
if obj <=>
min is less than zero or if obj <=>
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
static VALUE cmp_between(VALUE x, VALUE min, VALUE max) { return RBOOL((cmpint(x, min) >= 0 && cmpint(x, max) <= 0)); }
In (min, max)
form, 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'
If min is nil
, it is considered smaller than obj, and if max is nil
, it is considered greater than obj.
-20.clamp(0, nil) #=> 0 523.clamp(nil, 100) #=> 100
In (range)
form, returns range.begin if obj <=>
range.begin is less than zero, range.end if obj <=>
range.end 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'
If range.begin is nil
, it is considered smaller than obj, and if range.end is nil
, it is considered greater than obj.
-20.clamp(0..) #=> 0 523.clamp(..100) #=> 100
When range.end is excluded and not nil
, an exception is raised.
100.clamp(0...100) # ArgumentError
static VALUE cmp_clamp(int argc, VALUE *argv, VALUE x) { VALUE min, max; int c, excl = 0; if (rb_scan_args(argc, argv, "11", &min, &max) == 1) { VALUE range = min; if (!rb_range_values(range, &min, &max, &excl)) { rb_raise(rb_eTypeError, "wrong argument type %s (expected Range)", rb_builtin_class_name(range)); } if (!NIL_P(max)) { if (excl) rb_raise(rb_eArgError, "cannot clamp with an exclusive range"); } } if (!NIL_P(min) && !NIL_P(max) && cmpint(min, max) > 0) { rb_raise(rb_eArgError, "min argument must be less than or equal to max argument"); } if (!NIL_P(min)) { c = cmpint(x, min); if (c == 0) return x; if (c < 0) return min; } if (!NIL_P(max)) { c = cmpint(x, max); if (c > 0) return max; } return x; }