# Getting all classes within a module?
**URL:** https://rubytalk.org/t/getting-all-classes-within-a-module/1988
**Category:** ruby-talk
**Created:** [25 September 2002 21:43 UTC](https://rubytalk.org/t/getting-all-classes-within-a-module/1988 "2002-09-25T21:43:53Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Markus\_Jais](https://rubytalk.org/u/Markus_Jais)
#### Post date: [25 September 2002 21:43 UTC](https://rubytalk.org/t/getting-all-classes-within-a-module/1988/1 "2002-09-25T21:43:53Z")
hello
is there a way to get all classes defined within a module ?
something like this:
require "mymodule"
classes = mymodule.classes\_within\_this\_module
markus
---
### Author:  [@Joel\_VanderWerf1](https://rubytalk.org/u/Joel_VanderWerf1)
#### Post date: [25 September 2002 22:44 UTC](https://rubytalk.org/t/getting-all-classes-within-a-module/1988/2 "2002-09-25T22:44:42Z")
Markus Jais wrote:
> hello
>
> is there a way to get all classes defined within a module ?
>
> something like this:
>
> require “mymodule”
> classes = mymodule.classes\_within\_this\_module
```
^^^^^^^^ what is this?
```
In ruby, modules and files are different things, though they are often
in a one-to-one correspondence. I’ll assume that you are interested in
modules.
The following will give you all the classes defined in the scope of String.
String.constants.map {|x| String.const\_get x}.grep(Class)
But this includes things like Float that are defined in Object. So let’s
define:
class Module
def my\_classes
constants.map {|x| const\_get x}.grep(Class)
end
end
Then you can do
String.my\_classes - String.superclass.my\_classes
which will be empty, unless you add a class in String:
class String
class S; end
end
after which the subtraction will return:
[String::S]
One more twist: you may also want to subtract constants that come from a
mixin module.
module Enumerable
class E
end
end
String.my\_classes - String.superclass.my\_classes
# ==\> [String::S, Enumerable::E]
So let’s define:
class Module
def my\_own\_classes
my\_classes - ancestors.map {|a|
(a == self)? : a.my\_classes
}.flatten
end
end
String.my\_own\_classes
# ==\> [String::S]