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Module: Comparable

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In:
::Complex, ::File::Stat, ::Float, ::IO::Buffer, ::IO::Buffer::Slice, ::IO::Buffer::Storage, ::Integer, ::Numeric, ::Rational, ::String, ::Symbol, ::Time, ::Warning::buffer
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 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.

Instance Method Summary

Instance Method Details

#<(other) ⇒ Boolean

Returns whether self is "less than" other; equivalent to (self <=> other) < 0:

'foo' < 'foo'  # => false
'foo' < 'food' # => true
[ GitHub ] 

  


# File 'compar.c', line 159



static VALUE
cmp_lt(VALUE x, VALUE y)
{
    return RBOOL(cmpint(x, y) < 0);
}


  








  

    #<=(other)  ⇒ Boolean   



  

    
Returns whether self is "less than or equal to" other;
equivalent to (self <=> other) <= 0:


'foo' <= 'foo'  # => true
'foo' <= 'food' # => true
'food' <= 'foo' # => false

  



  [ GitHub ]


  

  


# File 'compar.c', line 178



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.

  



  [ GitHub ]


  

  


# File 'compar.c', line 93



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   



  

    
Returns whether self is "greater than" other;
equivalent to (self <=> other) > 0:


'foo' > 'foo'  # => false
'food' > 'foo' # => true

  



  [ GitHub ]


  

  


# File 'compar.c', line 122



static VALUE
cmp_gt(VALUE x, VALUE y)
{
    return RBOOL(cmpint(x, y) > 0);
}


  








  

    #>=(other)  ⇒ Boolean   



  

    
Returns whether self is "greater than or equal to" other;
equivalent to (self <=> other) >= 0:


'food' >= 'foo'  # => true
'foo'  >= 'foo'  # => true
'foo'  >= 'food' # => false

  



  [ GitHub ]


  

  


# File 'compar.c', line 141



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

  



  [ GitHub ]


  

  


# File 'compar.c', line 199



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


  








  

    

      #clamp(min, max)  ⇒ min, ... 
      #clamp(range)  ⇒ range.begin, ... 
    

  



  

    
Returns an object of the same type as self.


With non-nil arguments min and max given, returns:


    

  • min, if self <= min.
    • 

  • max, if self >= max.
    • 

  • self, otherwise.
    • 



Examples:


0.clamp(0, 9)   # => 0
-1.clamp(0, 9)  # => 0
9.clamp(0, 9)   # => 9
10.clamp(0, 9)  # => 9
5.clamp(0, 9)   # => 5


With nil argument min given and non-nil argument max given, returns:


    

  • max, if self >= max.
    • 

  • self, otherwise.
    • 



Examples:


9.clamp(nil, 9)  # => 9
10.clamp(nil, 9) # => 9
0.clamp(nil, 9)  # => 0


With non-nil argument min andnil argument max given, returns:


    

  • min, if self <= min.
    • 

  • self, otherwise.
    • 



Examples:


0.clamp(0, nil)  # => 0
-1.clamp(0, nil) # => 0
1.clamp(0, nil)  # => 1


With nil arguments min and max given, returns self:


0.clamp(nil, nil) # => 0
0.clamp(nil, nil) # => 0


In all cases above, raises ArgumentError if comparison fails.


With bounded range range given, returns:


    

  • range.begin, if self <= range.begin.
    • 

  • range.end, if self >= range.end.
    • 

  • self, otherwise.
    • 



Examples:


0.clamp(0..9)  # => 0
-1.clamp(0..9) # => 0
9.clamp(0..9)  # => 9
10.clamp(0..9) # => 9
5.clamp(0..9)  # => 5
5.clamp(0...9) # Raises ArgumentError:cannot clamp with an exclusive range.


With beginless range range given, returns:


    

  • range.end, if self >= range.end.
    • 

  • self, otherwise.
    • 



Examples:


9.clamp(nil..9)    # => 9
10.clamp(nil..9)    # => 9
0.clamp(nil..9)    # => 0
0.clamp(nil...9) # Raises ArgumentError: cannot clamp with an exclusive range.


With endless range range given, returns:


    

  • range.begin, if self <= range.begin.
    • 

  • self, otherwise.
    • 



Examples:


0.clamp(0..nil)  # => 0
-1.clamp(0..nil) # => 0
1.clamp(0..nil)  # => 1
1.clamp(0...nil) # => 1


With unbounded range range given, returns self:


0.clamp(nil..nil)  # => 0
0.clamp(nil...nil) # => 0

  





  


  [ GitHub ]


  

  


# File 'compar.c', line 324



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;
}