How to use define_method inside initialize()
I suspect that you're looking for define_singleton_method
:
define_singleton_method(symbol, method) → new_method
define_singleton_method(symbol) { block } → procDefines a singleton method in the receiver. The method parameter can be a
Proc
, aMethod
or anUnboundMethod
object. If a block is specified, it is used as the method body.
If you use define_method
on self.class
, you'll create the new method as an instance method on the whole class so it will be available as a method on all instances of the class.
You'd use define_singleton_method
like this:
class C
def initialize(s)
define_singleton_method(s) { puts "some method #{s}" }
end
end
And then:
a = C.new('a')
b = C.new('b')
a.a # puts 'some method a'
a.b # NoMethodError
b.a # NoMethodError
b.b # puts 'some method b'
If your initialize
did:
self.class.send(:define_method,n) { puts "some method #{n}" }
then you'd get:
a.a # puts 'some method a'
a.b # puts 'some method b'
b.a # puts 'some method a'
b.b # puts 'some method b'
and that's probably not what you're looking for. Creating a new instance and having the entire class change as a result is rather odd.
Do as below :
class C
def initialize(n)
self.class.send(:define_method,n) { puts "some method #{n}" }
end
end
ob = C.new("abc")
ob.abc
# >> some method abc
Module#define_method
is a private method and also a class method.Your one didn't work,as you tried to call it on the instance of C
.You have to call it on C
,using #send
in your case.