Module: Im::ModuleConstAdded

Defined in:
lib/im/module_const_added.rb

Instance Method Summary collapse

Instance Method Details

#const_added(const_name) ⇒ Object

We patch Module#const_added to track every time a constant is added to a permanently-named module pointing to an Im-autoloaded constant. This is important because the moment that an Im-autoloaded constant is attached to a permanently named module, its name changes permanently. Although Im internally avoids the use of absolute cpaths, ExplicitNamespace must use them and thus we need to update its internal registry accordingly.



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# File 'lib/im/module_const_added.rb', line 15

def const_added(const_name)
  # If we are called from an autoload, no need to track.
  return super if autoload?(const_name)

  # Get the name of this module and only continue if it is a permanent name.
  return unless cpath = Im.permanent_cpath(self)

  # We know this is not an autoloaded constant, so it is safe to fetch the
  # value. We fetch the value, get it's object_id, and check the registry to
  # see if it is an Im-autoloaded module.
  relative_cpath, loader, references = Im::Registry.autoloaded_modules[const_get(const_name).object_id]
  return super unless loader

  # Update the context for this const add. This is important for reloading so
  # we can reset inbound references when the autoloaded module is unloaded.
  references << [self, const_name]

  # Update all absolute cpath references to this module by replacing all
  # references to the original cpath with the new, permanently-named cpath.
  #
  # For example, if we had a module loader::Foo::Bar, and loader::Foo was
  # assigned to Baz like this:
  #
  #   Baz = loader::Foo
  #
  # then we must update cpaths from a string like
  #
  #   "#<Im::Loader ...>::Foo::Bar"
  #
  # to
  #
  #   "Baz::Bar"
  #
  # To do this, we take the loader's module_prefix ("#<Im::Loader ...>::"),
  # append to it the relative cpath of the constant ("Foo") and replace that by the new
  # name ("Baz"), roughly like this:
  #
  #   "#<Im::Loader ...>::Foo::Bar".gsub(/^#{"#<Im::Loader ...>::Foo"}/, "Baz")
  #
  prefix = relative_cpath ? "#{loader.module_prefix}#{relative_cpath}" : loader.module_prefix.delete_suffix("::")
  ::Im::ExplicitNamespace.__update_cpaths(prefix, "#{cpath}::#{const_name}")

  super
rescue NameError
  super
end