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, 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]What’s Here
Module Comparable provides these methods, all of which use method <=>:
-
#<: Returns whether
selfis less than the given object. -
#<=: Returns whether
selfis less than or equal to the given object. -
#==: Returns whether
selfis equal to the given object. -
#>: Returns whether
selfis greater than or equal to the given object. -
#>=: Returns whether
selfis greater than the given object. -
#between?: Returns
trueifselfis between two given objects. -
#clamp: For given objects
minandmax, or range(min..max), returns:-
minif(self <=> min) < 0. -
maxif(self <=> max) > 0. -
selfotherwise.
-
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
falseif obj<=>min is less than zero or if obj<=>max is greater than zero,trueotherwise. -
#clamp(min, max) ⇒ Object
In
(min, max)form, 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.
# File 'compar.c', line 132
static VALUE
cmp_lt(VALUE x, VALUE y)
{
return RBOOL(cmpint(x, y) < 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.
# File 'compar.c', line 146
static VALUE
cmp_le(VALUE x, VALUE y)
{
return RBOOL(cmpint(x, y) <= 0);
}
#==(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.
# File 'compar.c', line 78
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);
}
#>(other) ⇒ Boolean
Compares two objects based on the receiver’s <=> method, returning true if it returns a value greater than 0.
# File 'compar.c', line 104
static VALUE
cmp_gt(VALUE x, VALUE y)
{
return RBOOL(cmpint(x, y) > 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.
# File 'compar.c', line 118
static VALUE
cmp_ge(VALUE x, VALUE y)
{
return RBOOL(cmpint(x, y) >= 0);
}
#between?(min, max) ⇒ Boolean
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# File 'compar.c', line 167
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'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) #=> 100When range.end is excluded and not nil, an exception is raised.
100.clamp(0...100) # ArgumentError# File 'compar.c', line 215
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;
}