Getting ruby function object itself

Question

In Ruby, everything is supposed to be an object. But I have a big problem to get to the function object defined the usual way, like

def f
    "foo"
end

Unlike in Python, f is the function result, not the function itself. Therefore, f(), f, ObjectSpace.f are all "foo". Also f.methods returns just string method list.

How do I access the function object itself?

Answer 1

You simply use the method method. This will return the Method instance that matches with that method. Some examples:

>> def f
>>   "foo"
>> end
=> nil
>> f
=> "foo"
>> method(:f)
=> #<Method: Object#f>
>> method(:f).methods
=> [:==, :eql?, :hash, :clone, :call, :[], ...]
>> class SomeClass
>>   def f
>>     "bar"
>>   end
>> end
=> nil
>> obj = SomeClass.new
=> #<SomeClass:0x00000001ef3b30>
>> obj.method(:f)
=> #<Method: SomeClass#f>
>> obj.method(:f).methods
=> [:==, :eql?, :hash, :clone, :call, :[], ...]

Hope this helps.

Answer 2

The method method will give you a Method object

f = obj.method :f
puts f.call # or f[]

this f is bound to obj. You can also get an unbound method:

unbound_plus = Fixnum.instance_method('+')
plus_2 = unbound_plus.bind(2)

(There is also a unbind method)