# qualifier_attr
[][`qualifier_attr`]
[][`qualifier_attr`]
[][`qualifier_attr`/docs]
[][`qualifier_attr`/license]
[][`qualifier_attr`/dep_status]
> Procedural macro attributes for adding "qualifiers" to various items.
At the moment, the crate supports only functions and the following "qualifiers":
* `pub`, `pub(crate)`, ... - visibility qualifiers
* `async` - async qualifier
* `unsafe` - unsafe qualifier
* `const` - const qualifier
* `extern "ABI"` - ABI qualifier
## Examples
```rust
use qualifier_attr::fn_qualifiers;
// We can add a qualifier to a function
// with an attribute.
#[fn_qualifiers(const)]
fn const_fn() -> u32 { 42 }
const CONST_RES: u32 = const_fn();
// It's not so impresive on its own
// but with cfg_attr it can be conditional.
#[cfg_attr(feature = "extern_c", no_mangle, fn_qualifiers(pub, extern "C"))]
fn extern_c_fn() -> u32 { 42 }
```
Learn more about `cfg_attr` [here](https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute).
## Similar crates
* [`const_fn`](https://crates.io/crates/const_fn).
## License
<sup>
Licensed under either of <a href="LICENSE-APACHE">Apache License, Version
2.0</a> or <a href="LICENSE-MIT">MIT license</a> at your option.
</sup>
<br>
<sub>
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in this crate by you, as defined in the Apache-2.0 license, shall
be dual licensed as above, without any additional terms or conditions.
</sub>
[`qualifier_attr`]: https://crates.io/crates/qualifier_attr
[`qualifier_attr`/docs]: https://docs.rs/qualifier_attr
[`qualifier_attr`/license]: https://github.com/JohnScience/qualifier_attr#license
[`qualifier_attr`/dep_status]: https://deps.rs/repo/github/JohnScience/qualifier_attr