Commit Graph

7 Commits

Author SHA1 Message Date
Clar Fon
efda7f3f9c
Simpler lint fixes: makes ci lints work but disables a lint for now (#15376)
Takes the first two commits from #15375 and adds suggestions from this
comment:
https://github.com/bevyengine/bevy/pull/15375#issuecomment-2366968300

See #15375 for more reasoning/motivation.

## Rebasing (rerunning)

```rust
git switch simpler-lint-fixes
git reset --hard main
cargo fmt --all -- --unstable-features --config normalize_comments=true,imports_granularity=Crate
cargo fmt --all
git add --update
git commit --message "rustfmt"
cargo clippy --workspace --all-targets --all-features --fix
cargo fmt --all -- --unstable-features --config normalize_comments=true,imports_granularity=Crate
cargo fmt --all
git add --update
git commit --message "clippy"
git cherry-pick e6c0b94f6795222310fb812fa5c4512661fc7887
```
2024-09-24 11:42:59 +00:00
Gino Valente
83356b12c9
bevy_reflect: Replace "value" terminology with "opaque" (#15240)
# Objective

Currently, the term "value" in the context of reflection is a bit
overloaded.

For one, it can be used synonymously with "data" or "variable". An
example sentence would be "this function takes a reflected value".

However, it is also used to refer to reflected types which are
`ReflectKind::Value`. These types are usually either primitives, opaque
types, or types that don't fall into any other `ReflectKind` (or perhaps
could, but don't due to some limitation/difficulty). An example sentence
would be "this function takes a reflected value type".

This makes it difficult to write good documentation or other learning
material without causing some amount of confusion to readers. Ideally,
we'd be able to move away from the `ReflectKind::Value` usage and come
up with a better term.

## Solution

This PR replaces the terminology of "value" with "opaque" across
`bevy_reflect`. This includes in documentation, type names, variant
names, and macros.

The term "opaque" was chosen because that's essentially how the type is
treated within the reflection API. In other words, its internal
structure is hidden. All we can do is work with the type itself.

### Primitives

While primitives are not technically opaque types, I think it's still
clearer to refer to them as "opaque" rather than keep the confusing
"value" terminology.

We could consider adding another concept for primitives (e.g.
`ReflectKind::Primitive`), but I'm not sure that provides a lot of
benefit right now. In most circumstances, they'll be treated just like
an opaque type. They would also likely use the same macro (or two copies
of the same macro but with different names).

## Testing

You can test locally by running:

```
cargo test --package bevy_reflect --all-features
```

---

## Migration Guide

The reflection concept of "value type" has been replaced with a clearer
"opaque type". The following renames have been made to account for this:

- `ReflectKind::Value` → `ReflectKind::Opaque`
- `ReflectRef::Value` → `ReflectRef::Opaque`
- `ReflectMut::Value` → `ReflectMut::Opaque`
- `ReflectOwned::Value` → `ReflectOwned::Opaque`
- `TypeInfo::Value` → `TypeInfo::Opaque`
- `ValueInfo` → `OpaqueInfo`
- `impl_reflect_value!` → `impl_reflect_opaque!`
- `impl_from_reflect_value!` → `impl_from_reflect_opaque!`

Additionally, declaring your own opaque types no longer uses
`#[reflect_value]`. This attribute has been replaced by
`#[reflect(opaque)]`:

```rust
// BEFORE
#[derive(Reflect)]
#[reflect_value(Default)]
struct MyOpaqueType(u32);

// AFTER
#[derive(Reflect)]
#[reflect(opaque)]
#[reflect(Default)]
struct MyOpaqueType(u32);
```

Note that the order in which `#[reflect(opaque)]` appears does not
matter.
2024-09-23 18:04:57 +00:00
Benjamin Brienen
67615c5051
split bevy_reflect::derive::utilities into proper modules (#15354)
# Objective

- A utilities module is considered to be a bad practice and poor
organization of code, so this fixes it.

## Solution

- Split each struct into its own module
- Move related lose functions into their own module
- Move the last few bits into good places

## Testing

- CI

---------

Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2024-09-22 14:24:14 +00:00
Gino Valente
6183b56b5d
bevy_reflect: Reflect remote types (#6042)
# Objective

The goal with this PR is to allow the use of types that don't implement
`Reflect` within the reflection API.

Rust's [orphan
rule](https://doc.rust-lang.org/book/ch10-02-traits.html#implementing-a-trait-on-a-type)
prevents implementing a trait on an external type when neither type nor
trait are owned by the implementor. This means that if a crate,
`cool_rust_lib`, defines a type, `Foo`, then a user cannot use it with
reflection. What this means is that we have to ignore it most of the
time:

```rust
#[derive(Reflect)]
struct SomeStruct {
  #[reflect(ignore)]
  data: cool_rust_lib::Foo
}
```

Obviously, it's impossible to implement `Reflect` on `Foo`. But does it
*have* to be?

Most of reflection doesn't deal with concrete types— it's almost all
using `dyn Reflect`. And being very metadata-driven, it should
theoretically be possible. I mean,
[`serde`](https://serde.rs/remote-derive.html) does it.

## Solution

> Special thanks to @danielhenrymantilla for their help reviewing this
PR and offering wisdom wrt safety.

Taking a page out of `serde`'s book, this PR adds the ability to easily
use "remote types" with reflection. In this context, a "remote type" is
the external type for which we have no ability to implement `Reflect`.

This adds the `#[reflect_remote(...)]` attribute macro, which is used to
generate "remote type wrappers". All you have to do is define the
wrapper exactly the same as the remote type's definition:

```rust
// Pretend this is our external crate
mod cool_rust_lib {
  #[derive(Default)]
  struct Foo {
    pub value: String
  }
}

#[reflect_remote(cool_rust_lib::Foo)]
struct FooWrapper {
  pub value: String
}
```

> **Note:** All fields in the external type *must* be public. This could
be addressed with a separate getter/setter attribute either in this PR
or in another one.

The macro takes this user-defined item and transforms it into a newtype
wrapper around the external type, marking it as `#[repr(transparent)]`.
The fields/variants defined by the user are simply used to build out the
reflection impls.

Additionally, it generates an implementation of the new trait,
`ReflectRemote`, which helps prevent accidental misuses of this API.

Therefore, the output generated by the macro would look something like:

```rust
#[repr(transparent)]
struct FooWrapper(pub cool_rust_lib::Foo);

impl ReflectRemote for FooWrapper {
  type Remote = cool_rust_lib::Foo;

  // transmutation methods...
}

// reflection impls...
// these will acknowledge and make use of the `value` field
```

Internally, the reflection API will pass around the `FooWrapper` and
[transmute](https://doc.rust-lang.org/std/mem/fn.transmute.html) it
where necessary. All we have to do is then tell `Reflect` to do that. So
rather than ignoring the field, we tell `Reflect` to use our wrapper
using the `#[reflect(remote = ...)]` field attribute:

```rust
#[derive(Reflect)]
struct SomeStruct {
  #[reflect(remote = FooWrapper)]
  data: cool_rust_lib::Foo
}
```

#### Other Macros & Type Data

Because this macro consumes the defined item and generates a new one, we
can't just put our macros anywhere. All macros that should be passed to
the generated struct need to come *below* this macro. For example, to
derive `Default` and register its associated type data:

```rust
//  GOOD
#[reflect_remote(cool_rust_lib::Foo)]
#[derive(Default)]
#[reflect(Default)]
struct FooWrapper {
  pub value: String
}

//  BAD
#[derive(Default)]
#[reflect_remote(cool_rust_lib::Foo)]
#[reflect(Default)]
struct FooWrapper {
  pub value: String
}
```

#### Generics

Generics are forwarded to the generated struct as well. They should also
be defined in the same order:

```rust
#[reflect_remote(RemoteGeneric<'a, T1, T2>)]
struct GenericWrapper<'a, T1, T2> {
  pub foo: &'a T1,
  pub bar: &'a T2,
}
```

> Naming does *not* need to match the original definition's. Only order
matters here.

> Also note that the code above is just a demonstration and doesn't
actually compile since we'd need to enforce certain bounds (e.g. `T1:
Reflect`, `'a: 'static`, etc.)

#### Nesting

And, yes, you can nest remote types:

```rust
#[reflect_remote(RemoteOuter)]
struct OuterWrapper {
  #[reflect(remote = InnerWrapper)]
  pub inner: RemoteInner
}

#[reflect_remote(RemoteInner)]
struct InnerWrapper(usize);
```

#### Assertions

This macro will also generate some compile-time assertions to ensure
that the correct types are used. It's important we catch this early so
users don't have to wait for something to panic. And it also helps keep
our `unsafe` a little safer.

For example, a wrapper definition that does not match its corresponding
remote type will result in an error:

```rust
mod external_crate {
  pub struct TheirStruct(pub u32);
}

#[reflect_remote(external_crate::TheirStruct)]
struct MyStruct(pub String); // ERROR: expected type `u32` but found `String`
```

<details>
<summary>Generated Assertion</summary>

```rust
const _: () = {
  #[allow(non_snake_case)]
  #[allow(unused_variables)]
  #[allow(unused_assignments)]
  #[allow(unreachable_patterns)]
  #[allow(clippy::multiple_bound_locations)]
  fn assert_wrapper_definition_matches_remote_type(
    mut __remote__: external_crate::TheirStruct,
  ) {
    __remote__.0 = (|| -> ::core::option::Option<String> { None })().unwrap();
  }
};
```

</details>

Additionally, using the incorrect type in a `#[reflect(remote = ...)]`
attribute should result in an error:

```rust
mod external_crate {
  pub struct TheirFoo(pub u32);
  pub struct TheirBar(pub i32);
}

#[reflect_remote(external_crate::TheirFoo)]
struct MyFoo(pub u32);

#[reflect_remote(external_crate::TheirBar)]
struct MyBar(pub i32);

#[derive(Reflect)]
struct MyStruct {
  #[reflect(remote = MyBar)] // ERROR: expected type `TheirFoo` but found struct `TheirBar`
  foo: external_crate::TheirFoo
}
```

<details>
<summary>Generated Assertion</summary>

```rust
const _: () = {
    struct RemoteFieldAssertions;
    impl RemoteFieldAssertions {
        #[allow(non_snake_case)]
        #[allow(clippy::multiple_bound_locations)]
        fn assert__foo__is_valid_remote() {
            let _: <MyBar as bevy_reflect::ReflectRemote>::Remote = (|| -> ::core::option::Option<external_crate::TheirFoo> {
              None
            })().unwrap();
        }
    }
};
```

</details>

### Discussion

There are a couple points that I think still need discussion or
validation.

- [x] 1. `Any` shenanigans

~~If we wanted to downcast our remote type from a `dyn Reflect`, we'd
have to first downcast to the wrapper then extract the inner type. This
PR has a [commit](b840db9f74cb6d357f951cb11b150d46bac89ee2) that
addresses this by making all the `Reflect::*any` methods return the
inner type rather than the wrapper type. This allows us to downcast
directly to our remote type.~~

~~However, I'm not sure if this is something we want to do. For
unknowing users, it could be confusing and seemingly inconsistent. Is it
worth keeping? Or should this behavior be removed?~~

I think this should be fine. The remote wrapper is an implementation
detail and users should not need to downcast to the wrapper type. Feel
free to let me know if there are other opinions on this though!

- [x] 2. Implementing `Deref/DerefMut` and `From`

~~We don't currently do this, but should we implement other traits on
the generated transparent struct? We could implement `Deref`/`DerefMut`
to easily access the inner type. And we could implement `From` for
easier conversion between the two types (e.g. `T: Into<Foo>`).~~ As
mentioned in the comments, we probably don't need to do this. Again, the
remote wrapper is an implementation detail, and should generally not be
used directly.
     
- [x] 3. ~~Should we define a getter/setter field attribute in this PR
as well or leave it for a future one?~~ I think this should be saved for
a future PR

- [ ] 4. Any foreseeable issues with this implementation?

#### Alternatives

One alternative to defining our own `ReflectRemote` would be to use
[bytemuck's
`TransparentWrapper`](https://docs.rs/bytemuck/1.13.1/bytemuck/trait.TransparentWrapper.html)
(as suggested by @danielhenrymantilla).

This is definitely a viable option, as `ReflectRemote` is pretty much
the same thing as `TransparentWrapper`. However, the cost would be
bringing in a new crate— though, it is already in use in a few other
sub-crates like bevy_render.

I think we're okay just defining `ReflectRemote` ourselves, but we can
go the bytemuck route if we'd prefer offloading that work to another
crate.

---

## Changelog

* Added the `#[reflect_remote(...)]` attribute macro to allow `Reflect`
to be used on remote types
* Added `ReflectRemote` trait for ensuring proper remote wrapper usage
2024-08-12 19:12:53 +00:00
radiish
6ab8767d3b
reflect: implement the unique reflect rfc (#7207)
# Objective

- Implements the [Unique Reflect
RFC](https://github.com/nicopap/rfcs/blob/bevy-reflect-api/rfcs/56-better-reflect.md).

## Solution

- Implements the RFC.
- This implementation differs in some ways from the RFC:
- In the RFC, it was suggested `Reflect: Any` but `PartialReflect:
?Any`. During initial implementation I tried this, but we assume the
`PartialReflect: 'static` in a lot of places and the changes required
crept out of the scope of this PR.
- `PartialReflect::try_into_reflect` originally returned `Option<Box<dyn
Reflect>>` but i changed this to `Result<Box<dyn Reflect>, Box<dyn
PartialReflect>>` since the method takes by value and otherwise there
would be no way to recover the type. `as_full` and `as_full_mut` both
still return `Option<&(mut) dyn Reflect>`.

---

## Changelog

- Added `PartialReflect`.
- `Reflect` is now a subtrait of `PartialReflect`.
- Moved most methods on `Reflect` to the new `PartialReflect`.
- Added `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect}`.
- Added `PartialReflect::{try_as_reflect, try_as_reflect_mut,
try_into_reflect}`.
- Added `<dyn PartialReflect>::{try_downcast_ref, try_downcast_mut,
try_downcast, try_take}` supplementing the methods on `dyn Reflect`.

## Migration Guide

- Most instances of `dyn Reflect` should be changed to `dyn
PartialReflect` which is less restrictive, however trait bounds should
generally stay as `T: Reflect`.
- The new `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect, try_as_reflect, try_as_reflect_mut,
try_into_reflect}` methods as well as `Reflect::{as_reflect,
as_reflect_mut, into_reflect}` will need to be implemented for manual
implementors of `Reflect`.

## Future Work

- This PR is designed to be followed up by another "Unique Reflect Phase
2" that addresses the following points:
- Investigate making serialization revolve around `Reflect` instead of
`PartialReflect`.
- [Remove the `try_*` methods on `dyn PartialReflect` since they are
stop
gaps](https://github.com/bevyengine/bevy/pull/7207#discussion_r1083476050).
- Investigate usages like `ReflectComponent`. In the places they
currently use `PartialReflect`, should they be changed to use `Reflect`?
- Merging this opens the door to lots of reflection features we haven't
been able to implement.
- We could re-add [the `Reflectable`
trait](8e3488c880/crates/bevy_reflect/src/reflect.rs (L337-L342))
and make `FromReflect` a requirement to improve [`FromReflect`
ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is
currently not possible because dynamic types cannot sensibly be
`FromReflect`.
  - Since this is an alternative to #5772, #5781 would be made cleaner.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2024-08-12 17:01:41 +00:00
Gino Valente
faf003fc9d
bevy_reflect: enum_utility cleanup (#13424)
# Objective

The `enum_utility` module contains the `get_variant_constructors`
function, which is used to generate token streams for constructing
enums. It's used for the `FromReflect::from_reflect` implementation and
the `Reflect::try_apply` implementation.

Due to the complexity of enums, this function is understandably a little
messy and difficult to extend.

## Solution

Clean up the `enum_utility` module.

Now "clean" is a bit subjective. I believe my solution is "cleaner" in
that the logic to generate the tokens are strictly coupled with the
intended usage. Because of this, `try_apply` is also no longer strictly
coupled with `from_reflect`.

This makes it easier to extend with new functionality, which is
something I'm doing in a future unrelated PR that I have based off this
one.

## Testing

There shouldn't be any testing required other than ensuring that the
project still builds and that CI passes.
2024-05-22 21:18:57 +00:00
BD103
22305acf66
Rename bevy_reflect_derive folder to derive (#13269)
# Objective

- Some of the "large" crates have sub-crates, usually for things such as
macros.
- For an example, see [`bevy_ecs_macros` at
`bevy_ecs/macros`](4f9f987099/crates/bevy_ecs/macros).
- The one crate that does not follow this convention is
[`bevy_reflect_derive`](4f9f987099/crates/bevy_reflect/bevy_reflect_derive),
which is in the `bevy_reflect/bevy_reflect_derive` folder and not
`bevy_reflect/derive` or `bevy_reflect/macros`.

## Solution

- Rename folder `bevy_reflect_derive` to `derive`.
- I chose to use `derive` instead of `macros` because the crate name
itself ends in `_derive`. (One of only two crates to actually use this
convention, funnily enough.)

## Testing

- Build and test `bevy_reflect` and `bevy_reflect_derive`.
- Apply the following patch to `publish.sh` to run it in `--dry-run`
mode, to test that the path has been successfully updated:
- If you have any security concerns about applying random diffs, feel
free to skip this step. Worst case scenario it fails and Cart has to
manually publish a few crates.

```bash
# Apply patch to make `publish.sh` *not* actually publish anything.
git apply path/to/foo.patch
# Make `publish.sh` executable.
chmod +x tools/publish.sh
# Execute `publish.sh`.
./tools/publish.sh
```

```patch
diff --git a/tools/publish.sh b/tools/publish.sh
index b020bad28..fbcc09281 100644
--- a/tools/publish.sh
+++ b/tools/publish.sh
@@ -49,7 +49,7 @@ crates=(
 
 if [ -n "$(git status --porcelain)" ]; then
     echo "You have local changes!"
-    exit 1
+    # exit 1
 fi
 
 pushd crates
@@ -61,15 +61,15 @@ do
   cp ../LICENSE-APACHE "$crate"
   pushd "$crate"
   git add LICENSE-MIT LICENSE-APACHE
-  cargo publish --no-verify --allow-dirty
+  cargo publish --no-verify --allow-dirty --dry-run
   popd
-  sleep 20
+  # sleep 20
 done
 
 popd
 
 echo "Publishing root crate"
-cargo publish --allow-dirty
+cargo publish --allow-dirty --dry-run
 
 echo "Cleaning local state"
 git reset HEAD --hard
```

---

## Changelog

- Moved `bevy_reflect_derive` from
`crates/bevy_reflect/bevy_reflect_derive` to
`crates/bevy_reflect/derive`.
2024-05-07 07:55:32 +00:00