Upon reflection, the change that I'm proposing to Macro.Env.fetch_alias/2
does not make sense. If you have Baz, then it already evaluates to Foo.Bar.
Please ignore that portion of the proposal. :)
On Saturday, April 1, 2023 at 11:38:47 AM UTC-4 Zach Allaun wrote:
> *Context*
>
> Since Elixir 1.13, Macro.Env.fetch_alias/2 has existed as a mechanism to
> resolve an alias to its fully-qualified name. This has the limitation,
> however, that you cannot use the actual alias in the lookup.
>
> iex> alias Foo.Bar, as: Baz
> iex> Macro.Env.fetch_alias(__ENV__, :Baz)
> {:ok, Foo.Bar}
> iex> Macro.Env.fetch_alias(__ENV__, Baz)
> :error
>
> There is not a mechanism to go the other way without relying on the
> private aliases field in a Macro.Env struct.
>
> *Proposal*
>
> Introduce a new function, Macro.Env.fetch_aliased_as/2, that is able to
> look up the name that a module is aliased as. Additionally, extend the
> behavior of both Macro.Env.fetch_aliased_as/2 and Macro.Env.fetch_alias/2
> to accept qualified atoms.
>
> iex> alias Foo.Bar, as: Baz
> Baz
>
> iex> Macro.Env.fetch_alias(__ENV__, :Baz)
> {:ok, Foo.Bar}
> iex> Macro.Env.fetch_alias(__ENV__, Baz)
> {:ok, Foo.Bar}
> iex> Macro.Env.fetch_alias(__ENV__, :Unknown)
> :error
>
> iex> Macro.Env.fetch_aliased_as(__ENV__, :"Foo.Bar")
> {:ok, Baz}
> iex> Macro.Env.fetch_aliased_as(__ENV__, Foo.Bar}
> {:ok, Baz}
> iex> Macro.Env.fetch_aliased_as(__ENV__, Foo.Unknown)
> :error
>
> I'll submit a PR shortly for this change, but am happy to wait for any
> discussion that might happen here before it's acted on.
>
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