How can I choose which version of a module to include dynamically in Ruby?

Question

I\'m writing a small Ruby command-line application that uses fileutils from the standard library for file operations. Depending on how the user invokes the applicat

Answer 1

If you would like to avoid the "switch" and inject the module, the

def initialize(injected_module)
    class << self
        include injected_module
    end
end

syntax won't work (the injected_module variable is out of scope). You could use the self.class.send trick, but per object instance extending seems more reasonable to me, not only because it is shorter to write:

def initialize(injected_module = MyDefaultModule)
    extend injected_module
end

but also it minimizes the side effects - the shared and easily changable state of the class, which can result in an unexpected behavior in a larger project. In Ruby the is no real "privacy" so to say, but some methods are marked private not without a reason.