method
method_defined?
method_defined?(p1)
public
Returns true if the named method is defined by mod (or its included modules and, if mod is a class, its ancestors). Public and protected methods are matched.
module A def method1() end end class B def method2() end 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? "method3" #=> true C.method_defined? "method4" #=> false