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Jun 12, 2025
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Update README and top-level doc #54

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a93b15a
Update impl-tools top-level doc
dhardy Jun 12, 2025
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Update README
dhardy Jun 12, 2025
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26 changes: 15 additions & 11 deletions README.md
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Expand Up @@ -124,15 +124,17 @@ impl_tools::impl_scope! {

Note: `#[impl_default]` is matched within an `impl_scope!` regardless of imports.

### Impl Scope
### Impl Self

`impl_scope!` is a function-like macro used to define a type plus its
implementations. It supports `impl Self` syntax:
`#[impl_self]` provides `impl Self` syntax, avoiding the
need to repeat generics when writing impls on a local type definition.
This supercedes `impl_scope!` (except regarding `macro@impl_default`).

```rust
use std::fmt::Display;

impl_tools::impl_scope! {
#[impl_tools::impl_self]
mod NamedThing {
/// I don't know why this exists
pub struct NamedThing<T: Display, F> {
name: T,
Expand All @@ -155,8 +157,9 @@ impl_tools::impl_scope! {
}
```

Caveat: `rustfmt` won't currently touch the contents. Hopefully that
[can be fixed](https://github.com/rust-lang/rustfmt/pull/5538)!
Note that `struct NamedThing` is defined directly within the outer namespace,
not within the `mod NamedThing`. This is a hack required to ensure the contents
use valid Rust syntax and are thus formattable using `cargo fmt`.

### Impl Anon

Expand Down Expand Up @@ -190,7 +193,7 @@ Our macros cannot be extended in the same way, but they can be extended via a ne
1. Create a copy of the `impl-tools` crate to create a new "front-end" (`proc-macro` crate).
This crate is contains only a little code over the [`impl-tools-lib`] crate.
2. To extend `#[autoimpl]`, write an impl of [`ImplTrait`] and add it to the attribute's definition.
To extend `impl_scope!`, write an impl of [`ScopeAttr`] and add it to the macro's definition.
To extend `#[impl_self]`, write an impl of [`ScopeAttr`] and add it to the macro's definition.
3. Depend on your new front end crate instead of `impl-tools`.

For an example of this approach, see [kas-macros](https://github.com/kas-gui/kas/tree/master/crates/kas-macros).
Expand All @@ -203,10 +206,7 @@ For an example of this approach, see [kas-macros](https://github.com/kas-gui/kas
Supported Rust Versions
------------------------------

The MSRV is 1.61.0.

When using a sufficiently recent compiler version (presumably 1.65.0), generic associated types
are supported (only applicable to `#[autoimpl]` on trait definitions using GATs).
The MSRV is 1.65.0.


Alternatives
Expand Down Expand Up @@ -273,6 +273,10 @@ trait Foo {
}
```

[derive-where](https://crates.io/crates/derive-where) is a variant of the
standard `#[derive]` macro supporting custom generic bounds.
(This offers a subset of the functionality of `#[autoimpl]`).


Copyright and Licence
---------------------
Expand Down
15 changes: 6 additions & 9 deletions src/lib.rs
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Expand Up @@ -12,21 +12,18 @@
//! [`#[autoimpl]`](macro@autoimpl) is an alternative to
//! [`#[derive]`](macro@derive) with more features (also usable on traits).
//!
//! [`#[impl_default]`](macro@impl_default) is shorthand for implementing
//! [`Default`] with an explicit default value.
//! It supports structs and enums.
//! [`#[impl_default]`](macro@impl_default) is an alternative to
//! `#[derive(Default)]` supporting field initializers.
//!
//! [`impl_scope!`] is a function-like macro used to define a type together with
//! its implementations. This allows:
//!
//! - `impl Self` syntax (avoid repeated definitions of generics)
//! - Evaluation of some more complex attribute macros
//! [`#[impl_self]`](macro@impl_self) provides `impl Self` syntax, avoiding the
//! need to repeat generics when writing impls on a local type definition.
//! This supercedes [`impl_scope!`] (except regarding [`macro@impl_default`]).
//!
//! [`impl_anon!`] is a function-like macro used to define and instantiate a
//! unique (single-use) type. It supports everything supported by [`impl_scope!`]
//! plus field initializers and (limited) automatic typing of fields.
//!
//! User-extensions to both [`#[autoimpl]`](macro@autoimpl) and [`impl_scope!`]
//! User-extensions to both [`#[autoimpl]`](macro@autoimpl) and [`macro@impl_self`]
//! are possible with a custom proc-macro crate depending on
//! [impl-tools-lib](https://crates.io/crates/impl-tools-lib).
Expand Down