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comp.lang.ruby

Find all subclasses of a class/module

James Coglan

8/21/2008 1:55:00 PM

[Note: parts of this message were removed to make it a legal post.]

Hi list,

I'm trying to find all the classes/modules that descend from a particular
class/module. Please tell me there's a better way than this:

http://gist.githu...

--
James Coglan
4 Answers

black eyes

8/21/2008 2:46:00 PM

0


the following are code in http://gist.githu...

class Module
def subclasses
classes = []
ObjectSpace.each_object do |klass|
next unless Module === klass
classes << klass if self > klass
end
classes
end
end

I think the above code is good! but considering the class and module are
referenced by constants in ruby, use Module.constants is more naturally!
the following are mine!

the key is to get rid of the real constant such as PI and so on.

def find_children p_klass
Module.constants.find_all{|c_klass| c_klass!=c_klass.upcase ? p_klass
> (Object.const_get c_klass) : nil}
end

# test!

class MyString < String
end

puts find_children( String) #=> MyString


require 'benchmark'
include Benchmark

puts find_children(Benchmark).include?(Tms) #=> fase
puts Tms.name #=> Benchmark::Tms
puts find_children(Benchmark).include?("Tms") #=> true

--
Posted via http://www.ruby-....

ara.t.howard

8/21/2008 2:50:00 PM

0


On Aug 21, 2008, at 7:55 AM, James Coglan wrote:

> Hi list,
>
> I'm trying to find all the classes/modules that descend from a
> particular
> class/module. Please tell me there's a better way than this:
>
> http://gist.githu...
>
> --
> James Coglan

just let ruby track it for you:

cfp:~ > cat a.rb
class A
end

class B < A
end

class C < A
end

class D < B
end

p D => D.subclasses
p C => C.subclasses
p B => B.subclasses
p A => A.subclasses
p Object => Object.subclasses



BEGIN {
class Class
def inherited other
super if defined? super
ensure
( @subclasses ||= [] ).push(other).uniq!
end

def subclasses
@subclasses ||= []
@subclasses.inject( [] ) do |list, subclass|
list.push(subclass, *subclass.subclasses)
end
end
end
}




cfp:~ > ruby a.rb
{D=>[]}
{C=>[]}
{B=>[D]}
{A=>[B, D, C]}
{Object=>[A, B, D, C]}


a @ http://codeforp...
--
we can deny everything, except that we have the possibility of being
better. simply reflect on that.
h.h. the 14th dalai lama

James Coglan

8/21/2008 4:28:00 PM

0

[Note: parts of this message were removed to make it a legal post.]

>
>
> BEGIN {
> class Class
> def inherited other
> super if defined? super
> ensure
> ( @subclasses ||= [] ).push(other).uniq!
> end
>
> def subclasses
> @subclasses ||= []
> @subclasses.inject( [] ) do |list, subclass|
> list.push(subclass, *subclass.subclasses)
> end
> end
> end
> }



That's probably more efficient than my version, but won't it fail to capture
relationships of any pre-existing classes? Seems it will only affect classes
defined after it has been loaded.

ara.t.howard

8/21/2008 8:05:00 PM

0


On Aug 21, 2008, at 10:27 AM, James Coglan wrote:

> That's probably more efficient than my version, but won't it fail to
> capture
> relationships of any pre-existing classes? Seems it will only affect
> classes
> defined after it has been loaded.


that's correct. generally that's what people are after.


a @ http://codeforp...
--
we can deny everything, except that we have the possibility of being
better. simply reflect on that.
h.h. the 14th dalai lama