Typeerror: Superclass Mismatch for Class Word in Ruby

TypeError: superclass mismatch for class Word in Ruby

A thumb rule for irb (either way irb or rails console)

If you are creating the same class twice with inheritance (superclass), exit the irb instance and create it again. Why this? Because otherwise class conflicts will happen.

In your case, you are using Windows (found from the question), so just type exit on DOS prompt and again type irb or rails console and create your Word class and it should work. Please let me know if it doesn't work for you.

Superclass mismatch for class in Ruby

lib/command/group/add.rb may get loaded before lib/command/group.rb. Hence in the latter, it appears as if you try to change which class Group inherits from.

The band aid solution would be to point to the same subclass in all files. Aka in lib/command/group/add.rb, you should add < Command.

The real solution should be to never use a class/module for namespacing and attach functionality to it.

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^{This issue was raised in Euruko 2016 and Matz said they might consider a special keyword for it. [Citation needed]}

Ruby on Rails 3 : superclass mismatch for class ...

You already have a Word class defined elsewhere. I tried within a Rails 3 app but was not able to replicate.

If you have not created a second Word class yourself, it is likely one of your Gems or plugins already defines it.

Superclass mismatch for class

The Email class must already be defined somewhere else.

You can test that by using the defined? method like this:

defined?(Email)

Think about namespacing your code by using a module:

module MyNameSpace
  class MyClass
  end
end

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superclass mismatch for class Queue (TypeError)

The script adds a class Queue like this:

class Queue < Debitable 
end

Ruby 2.1 introduced its own Queue class which inherits from Object. This leads to the error you mention.

Following script demonstrates the problem:

class Thing < Object
end

class Thing < String
end

If you run it then Ruby will tell you that it has a superclass mismatch for class Thing (TypeError)

Two ways to solve this:

• Use Ruby < 2.1 so the Queue class does not exist (which is kind of sad and not recommended)
• update the script, replace all occurences of Queue with MyQueue (you are free to come up with a better name)

Potentially a 6 year old script contains other problems as well... so good luck.

Also: if you really need different ruby version you can look at a ruby version manager like RVM or RBEnv.

` module:Rails ': superclass mismatch for class Server (TypeError)

A better way to do what you want:

require 'rails/commands/server'

module DefaultOptions
  def default_options
    super.merge!(Port: 8081)
  end
end

Rails::Server.prepend(DefaultOptions)

The reason for the error message is because you are attempting to redefine the Rails::Server class and changing it's inheritance structure. Rails::Server inherits from ::Rack::Server, however your code is trying to say it no longer does. Therefore, you get your superclass mismatch error.

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