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 whether self 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?: Returns true if self is between two given objects.
clamp: For given objects min and max, or range (min..max), returns:
- min if (self <=> min) < 0.
- max if (self <=> max) > 0.
- self otherwise.

Public Instance Methods

obj < other → true or false

Source

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 0.

obj <= other → true or false

Source

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 a value less than or equal to 0.

obj == other → true or false

Source

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 0. Also returns true if obj and other are the same object.

obj > other → true or false

Source

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 0.

obj >= other → true or false

Source

static VALUE cmp_ge(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.

between?(min, max) → true or false

Source

static VALUE cmp_between(VALUE x, VALUE min, VALUE max) {     return RBOOL((cmpint(x, min) >= 0 && cmpint(x, max) <= 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

clamp(min, max) → obj

clamp(range) → obj

Source

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; }

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