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instance method

Module#method_defined?

(::interned name, ?::boolish inherit) -> bool

mod.method_defined?(symbol, inherit=true, include_all = false) → true or false

mod.method_defined?(string, inherit=true, include_all = false) → true or false

static VALUE
rb_mod_method_defined(int argc, VALUE *argv, VALUE mod)
{
    VALUE mid, include_super, include_private;

    rb_scan_args(argc, argv, "12", &mid, &include_super, &include_private);
    if (argc < 3) {
        include_private = Qfalse;
        if (argc < 2) {
            include_super = Qtrue;
        }
    }

    rb_method_visibility_t visi = check_definition_visibility(mod, mid, RTEST(include_super));
    switch (visi) {
      case METHOD_VISI_UNDEF:
        return Qfalse;
      case METHOD_VISI_PUBLIC:
      case METHOD_VISI_PROTECTED:
        return Qtrue;
      case METHOD_VISI_PRIVATE:
        return RBOOL(RTEST(include_private));
      default:
        UNREACHABLE_RETURN(Qundef);
    }
}

Returns true if the named method is defined by mod. If inherit is set, the lookup will also search mod’s ancestors. By default only public and protected methods are matched, but if include_all is set the lookup will also consider private methods. String arguments are converted to symbols.

Example

module A
  def method1()  end
  def protected_method1()  end
  protected :protected_method1
end
class B
  def method2()  end
  def private_method2()  end
  private :private_method2
end
class C < B
  include A
  def method3()  end
end

A.method_defined? :method1                       #=> true
C.method_defined? "method1"                      #=> true
C.method_defined? "method2"                      #=> true
C.method_defined? "method2", true                #=> true
C.method_defined? "method2", false               #=> false
C.method_defined? "method3"                      #=> true
C.method_defined? "protected_method1"            #=> true
C.method_defined? "method4"                      #=> false
C.method_defined? "private_method2"              #=> false
C.method_defined? "private_method2", true, true  #=> true
C.method_defined? "private_method2", false, true #=> false

Ruby version changes

4.1
- Module#method_defined? now accepts a third optional argument to also match private methods. [Feature #22297]

See also #method_added #method_removed #instance_methods #method_undefined also in 4.0 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

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