On Tue, Nov 6, 2012 at 12:37 PM, Aaron Patterson
<[email protected]> wrote:
> Hi,
>
> I've changed `const_get` in Ruby 2.0. If it were implemented in 1.9, it
> would look roughly like this:
>
> def const_get name, inherited = true
> name.to_s.split('::').inject(self.class) do |klass, name|
> klass.const_get name, inherited
> end
> end
>
> I was hoping we could use this to replace the implementation of
> `constantize`, but it seems we have an inconsistency in the way that
> `constantize` works in regard to constant inheritance.
>
> I've written a test to demonstrate the problem:
>
> https://gist.github.com/4024158
>
> For some reason `constantize` inherits constants, but not when the
> constant is defined on Object, where `const_get` in Ruby 2.0 will always
> honor the inheritance (even if the constant is defined at the top).
>
> Is there any chance we can change this?
Yeah, at first sight they seem to be different in their intention. The
new const_get is implemented as a recursive const_get, whereas
constantize is closer to emulate the resolution algorithm for constant
paths.
The subtle difference is in modules, as the test shows.
As you know, X::String raises a NameError if X is a module, and
resolves with a warning if X is a class that inherits from Object,
because Object is among its ancestors but the access is considered
dubious anyway. That's what constantize kinda emulates. I believe
"constantize" also raises if X is a class, and always treats the first
constant in the path as if it had a leading double colon "::", that's
why I say "kinda".
"Admin::UsersController".constantize fails if such controller does not
exist, regardless of the existence of an eventual top-level
UsersController, whereas if I understand it correctly
Object.const_get("Admin::UsersController", true) would resolve to such
top-level controller, because the original const_get name, inherit
does check Object by hand for modules, as the algorithm for relative
constant names does.
Not sure about changing that behavior.
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