Module: T::Private::ClassUtils

Defined in:
lib/types/private/class_utils.rb

Overview

Cut down version of Chalk::Tools::ClassUtils with only :replace_method functionality. Extracted to a separate namespace so the type system can be used standalone.

Defined Under Namespace

Classes: ReplacedMethod

Class Method Summary collapse

Class Method Details

.replace_method(mod, name, &blk) ⇒ Object

Replaces a method, either by overwriting it (if it is defined directly on ‘mod`) or by overriding it (if it is defined by one of mod’s ancestors). Returns a ReplacedMethod instance on which you can call ‘bind(…).call(…)` to call the original method, or `restore` to restore the original method (by overwriting or removing the override).



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# File 'lib/types/private/class_utils.rb', line 74

def self.replace_method(mod, name, &blk)
  original_method = mod.instance_method(name)
  original_visibility = visibility_method_name(mod, name)
  original_owner = original_method.owner

  mod.ancestors.each do |ancestor|
    break if ancestor == mod
    if ancestor == original_owner
      # If we get here, that means the method we're trying to replace exists on a *prepended*
      # mixin, which means in order to supersede it, we'd need to create a method on a new
      # module that we'd prepend before `ancestor`. The problem with that approach is there'd
      # be no way to remove that new module after prepending it, so we'd be left with these
      # empty anonymous modules in the ancestor chain after calling `restore`.
      #
      # That's not necessarily a deal breaker, but for now, we're keeping it as unsupported.
      raise "You're trying to replace `#{name}` on `#{mod}`, but that method exists in a " \
            "prepended module (#{ancestor}), which we don't currently support. Talk to " \
            "#dev-productivity for help."
    end
  end

  overwritten = original_owner == mod
  mod.send(:define_method, name, &blk) # rubocop:disable PrisonGuard/UsePublicSend
  mod.send(original_visibility, name) # rubocop:disable PrisonGuard/UsePublicSend
  new_method = mod.instance_method(name)

  ReplacedMethod.new(mod, original_method, new_method, overwritten, original_visibility)
end