Re: [PATCH proxmox v4 03/21] api-macro: support shared state extraction type

["Lukas Wagner" <l.wagner@proxmox.com>]

On Thu Sep 3, 2026 at 8:49 AM CEST, Lukas Wagner wrote:
> The #[state] attribute marks types that come from the registry, which
> allows telling them apart from regular API parameters. The API macro
> recognizes them in API handler signatures and looks them up in the
> shared state registry of the RpcEnvironment, instead of deserializing
> them from the request parameters. That way a handler declares its
> dependencies on application state in its signature and does not have to
> access the environment by hand.
>
> State arguments can either be taken by value or by reference, the latter
> avoids a clone in the method generated by the API macro. Taking the
> argument by reference is mutually exclusive with a mutable
> `RpcEnvironment` reference, since the state argument is borrowed from
> the environment. The macro shows a distinct error message in this case,
> educating the developer to use a by-value argument instead.
>
> If we ever decide to store shared state outside the rpc-environment,
> this restriction can be lifted.

after some discussion with wolfgang, we decided that references will not
be supported for now. In PDM, we only take by-value at the moment,
since PdmApplication is a thin wrapper around an Arc anyway.

We can always add support for reference types later.