CODEWITHSUNDEEP
ruby
Viet
Viet

Reputation: 583

Superclass mismatch for class

When I wrote the following code, it runs normally:

class Application
  def initialize(name)
    @name = name
  end
end

class Email2 < Application
end

But when I changed Email2 to Email like this:

class Application
  def initialize(name)
    @name = name
  end
end

class Email < Application
end

I got the error message: superclass mismatch for class Email. Please help me.

Upvotes: 3

Views: 10390

Answers (2)

user2536065
user2536065

Reputation:

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

Looks like you need to remove the definition from the CodeAcademy Context. Try deleting your browser cookies and refreshing the page.

Upvotes: 8

Jesper
Jesper

Reputation: 4555

The error occurs because there's already a class Email defined somewhere else, that inherits from something else than Application.

When using the class keyword, if the class already exists ruby will try to reopen the class, allowing you to add things to the existing class definition.

If you write class Email < Application, ruby will try to make Email inherit from Application. Ruby classes can't have more than one parent class, so if the existing Email class already inherits from something else, you will get this error.

To inherit from Message, you write this: class Email < Message

Upvotes: 4

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