Merge branch 'requirements-for-methods' into 'main'

book: Inform about Value conversions for properties

Closes #318

See merge request dbus/zbus!666

CONTRIBUTING.md

@@ -90,8 +90,8 @@ cargo clippy -- -D warnings
 ```
 
 Please not that there are times when clippy is wrong and you know what you are doing. In such cases,
-it's acceptable to tell clippy to [ignore the specific error or warning in the code](
-https://github.com/rust-lang/rust-clippy#allowingdenying-lints).
+it's acceptable to tell clippy to
+[ignore the specific error or warning in the code](https://github.com/rust-lang/rust-clippy#allowingdenying-lints).
 
 If you intend to contribute often or think that's very likely, we recommend you setup the following git
 hooks:
@@ -127,7 +127,7 @@ hooks:
 
 * Pre-push hook that goes in the `.git/hooks/pre-push` file:
 
-  ```
+  ```sh
   if ! which rustup &> /dev/null; then
       curl https://sh.rustup.rs -sSf  | sh -s -- -y
       export PATH=$PATH:$HOME/.cargo/bin

book/src/client.md

@@ -326,6 +326,16 @@ Environment variables:
   ...
 ```
 
+#### Trait-bounds for property values
+
+If you use custom types for property values, you might get a compile error for missing
+`From<zvariant::Value<'_>>` and/or `From<OwnedValue>` implementations. This is because properties
+are always sent as Variants on the bus, so you need to implement these conversions for your custom
+types.
+
+Not to worry though, the `zvariant` crate provides a [`Value`] and [`OwnedValue`] derive macro to
+implement these conversions for you.
+
 #### Watching for changes
 
 By default, the proxy will cache the properties and watch for changes.
@@ -556,5 +566,7 @@ There you have it, a Rust-friendly binding for your D-Bus service!
 [`pkg-config`]: https://www.freedesktop.org/wiki/Software/pkg-config/
 [cob]: blocking.html
 [`Stream`]: https://docs.rs/futures/0.3.17/futures/stream/trait.Stream.html
+[`Value`]: https://docs.rs/zvariant/latest/zvariant/derive.Value.html
+[`OwnedValue`]: https://docs.rs/zvariant/latest/zvariant/derive.OwnedValue.html
 
 [^busctl]: `busctl` is part of [`systemd`](https://www.freedesktop.org/wiki/Software/systemd/).