Remove the module namespace of a qualified Ruby class name

If (for some reason that you don't want to ask yourself) you need to know all classes that define a method with a given name, you can do it like this:

def classes_defining_method(method_name)
  method_name = method_name.to_sym
  Objec...

This can happen during development when classes without automatic reloading are pointing to classes with automatic reloading. E.g. some class in lib is calling Model.static_method.

Workaround A

Stop referencing autoloaded classes fro...

If you want to find out whether a Class object is directly inheriting from another class, use superclass:

ActiveRecord::RecordNotFound.super_class == ActiveRecord::ActiveRecordError # => true

To check if an...

TLDR: Ruby class variables (@@foo) are dangerous in many ways. You should avoid them at all cost. See bottom of this card for alternatives.

Class variables are shared between a class hierarchy
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Redis.current will be removed without replacement in redis-rb 5.0.
Version 4.6.0 adds deprecation warnings for Redis.current and Redis.current=:

`Redis.current=` is deprecated and will be removed in 5.0.

If your application still ...

Use Socket.gethostname. So for a machine whose hostname is "happycat", it will look like this:

>> Socket.gethostname
=> "happycat"

That should work right away for your Rails application. For plain Ruby, you first need to do:

requi...

This card will show you a cool way to define a class using Struct.new.
A common usecase for Structs are temporary data structures which just hold state and don't provide behaviour. In many cases you c...

In the discussion of the difference between include and extend in Ruby, there is a misconception that extend would add methods to the singleton class of a ruby object as stated in many posts on this topic. But in fact, it is added to the a...

Imagine you have a piece of code that tries to send a request to a remote server. Now the server is temporarily not available and raises an exception. In order to re-send the request you could use the following snippet:

def remote_request

...