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 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]

Public Instance Methods

obj < other → true or false click to toggle source

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

obj <= other → true or false click to toggle source

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

obj == other → true or false click to toggle source

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

obj> other → true or false click to toggle source

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

obj>= other → true or false click to toggle source

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

between?(min, max) → true or false click to toggle source

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

clamp(min, max) → obj click to toggle source

clamp(range) → obj

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'

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 smaller than 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;
}