method

<=

v1_8_7_330 - Show latest stable - 1 note - Class: Module

<=(p1) public

Returns true if mod is a subclass of other or is the same as other. Returns nil if there’s no relationship between the two. (Think of the relationship in terms of the class definition: “class A<B” implies “A<B”).

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/*
 * call-seq:
 *   mod <= other   =>  true, false, or nil
 *
 * Returns true if <i>mod</i> is a subclass of <i>other</i> or
 * is the same as <i>other</i>. Returns 
 * <code>nil</code> if there's no relationship between the two. 
 * (Think of the relationship in terms of the class definition: 
 * "class A<B" implies "A<B").
 *
 */

VALUE
rb_class_inherited_p(mod, arg)
    VALUE mod, arg;
{
    VALUE start = mod;

    if (mod == arg) return Qtrue;
    switch (TYPE(arg)) {
      case T_MODULE:
      case T_CLASS:
        break;
      default:
        rb_raise(rb_eTypeError, "compared with non class/module");
    }

    if (FL_TEST(mod, FL_SINGLETON)) {
        if (RCLASS(mod)->m_tbl == RCLASS(arg)->m_tbl)
            return Qtrue;
        mod = RBASIC(mod)->klass;
    }
    while (mod) {
        if (RCLASS(mod)->m_tbl == RCLASS(arg)->m_tbl)
            return Qtrue;
        mod = RCLASS(mod)->super;
    }
    /* not mod < arg; check if mod > arg */
    while (arg) {
        if (RCLASS(arg)->m_tbl == RCLASS(start)->m_tbl)
            return Qfalse;
        arg = RCLASS(arg)->super;
    }
    return Qnil;
}

January 11, 2010

0 thanks

Includes descendants

May be helpful to know that this returns true if A is any descendant of B, not just a direct one. As an example:

class Foo; end
class Bar < Foo; end
class Baz < Bar; end

Bar <= Foo #=> true
Baz <= Foo #=> true

<=

Related methods

Includes descendants