質問

I have a utility class defined with a bunch of class methods. In the Rails console, when I search for the class using Object.const_defined? it returns false. But after calling one of the class methods or creating an instance of the class, Object.const_defined? returns true. Is this because of some kind of lazy loading instantiation kind of thing? Is there another way I can check for the existence of a class which will return true, even if I haven't instantiated anything yet?

役に立ちましたか?

解決

This is kind of a hack, but it works

Object.const_get(:ClassName).is_a?(Class) rescue false

Above statement will return true if the class is defined and return false otherwise

他のヒント

You can use safe_constantize.

  your_class = "YourClassName".safe_constantize
  if your_class && your_class.class == Class
    your_class.new(options).run
  end
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