Item order in Object#methods

Ruby
1

Hi all,

please consider two files: init.rb and init_2.rb. In init.rb put this
bunch of code:

module Foo
def init
self.methods.collect { |meth| meth if meth =~ /init_/ }.compact.each
do |init_meth|
self.send(init_meth.to_sym)
end
end
end

class Bar
include Foo
def initialize
init
end
def init_1
puts “Method init_1 called!”
end
end

class Bar
def init_2
puts “Method init_2 called!”
end
def init_3
puts “Method init_3 called!”
end
def init_4
puts “Method init_4 called!”
end
end

Then in init_2.rb put another bunch of code:

require ‘init’

class Bar
def init_5
puts “Method init_5 called!”
end
def init_6
puts “Method init_6 called!”
end
end

Bar.new

Now execute init_2.rb. I get the following result:

Method init_4 called!
Method init_5 called!
Method init_6 called!
Method init_1 called!
Method init_2 called!
Method init_3 called!

but I expected:

Method init_1 called!
Method init_2 called!
Method init_3 called!
Method init_4 called!
Method init_5 called!
Method init_6 called!

So, which is the sort criteria of the array returned by Object#methods?

Thanks a lot!
Andrea

2

On Dec 18, 2006, at 10:08 AM, Andrea F. wrote:

end
end
end

…

So, which is the sort criteria of the array returned by
Object#methods?

Thanks a lot!
Andrea

If it’s important, why not sort them first:
self.methods.sort.collect { … }

-Rob

Rob B. http://agileconsultingllc.com
[email protected]

3

Rob B. wrote:

If it’s important, why not sort them first:
self.methods.sort.collect { … }

Because I’m interested to the methods’ definition order inside the class
not to the alphabetical order of methods’ name. The names init_1,
init_2, etc. were just an example.

Andrea

4

On Dec 18, 2006, at 10:32 AM, Andrea F. wrote:

Rob B. wrote:

If it’s important, why not sort them first:
self.methods.sort.collect { … }

Because I’m interested to the methods’ definition order inside the
class not to the alphabetical order of methods’ name. The names
init_1, init_2, etc. were just an example.

Andrea

I’d not be surprised to hear (from someone who actually knows rather
than speculates :wink: that the methods are stored in a hash and there
is no definite order to them. As for the order in which they were
defined, that’s just the order in which they were encountered.

When I run the code from your first message:
rab:ruby $ ruby init_2.rb
Method init_3 called!
Method init_4 called!
Method init_5 called!
Method init_6 called!
Method init_1 called!
Method init_2 called!

It’s not even the same order as yours (although it is consistent when
I run it multiple times). If the lookup is really hash-based,
defining other methods could “shuffle” these around if the underlying
hash table was expanded. (I’m using “hash” in its algorithmic sense,
not a Ruby class.)

-Rob

Rob B. http://agileconsultingllc.com
[email protected]