Posted almost 6 years ago. Visible to the public. Repeats. Linked content.

Ruby: What extend and include do

All Rubyists should be familiar with the common definitions for include and extend. You include a module to add instance methods to a class and extend to add class methods. Unfortunately, this common definition isn’t entirely accurate. It fails to explain why we use instance.extend(Module) to add methods to an instance. Shouldn’t it be instance.include(Module)? To figure this out we’re going to start by discussing where methods are stored.

Further reading

After you understood include and extend you might want to look into more Ruby metaprogramming basics:

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Dominik Schöler
Last edit:
over 3 years ago
by Pascal Schmid
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Posted by Dominik Schöler to makandra dev
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