Skip to content

add some docs to From conversions #51474

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jun 10, 2018
Merged

add some docs to From conversions #51474

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
52 changes: 39 additions & 13 deletions src/libcore/num/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4709,30 +4709,56 @@ pub use num::dec2flt::ParseFloatError;
// Conversions T -> T are covered by a blanket impl and therefore excluded
// Some conversions from and to usize/isize are not implemented due to portability concerns
macro_rules! impl_from {
($Small: ty, $Large: ty, #[$attr:meta]) => {
($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
#[$attr]
#[doc = $doc]
impl From<$Small> for $Large {
#[inline]
fn from(small: $Small) -> $Large {
small as $Large
}
}
};
($Small: ty, $Large: ty, #[$attr:meta]) => {
impl_from!($Small,
$Large,
#[$attr],
concat!("Converts `",
stringify!($Small),
"` to `",
stringify!($Large),
"` losslessly."));
}
}

macro_rules! impl_from_bool {
($target: ty, #[$attr:meta]) => {
impl_from!(bool, $target, #[$attr], concat!("Converts a `bool` to a `",
stringify!($target), "`. The resulting value is `0` for `false` and `1` for `true`
values.

# Examples

```
assert_eq!(", stringify!($target), "::from(true), 1);
assert_eq!(", stringify!($target), "::from(false), 0);
```"));
};
}

// Bool -> Any
impl_from! { bool, u8, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, u16, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, u32, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, u64, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, u128, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, usize, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, i8, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, i16, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, i32, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, i64, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, i128, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from! { bool, isize, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { u8, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { u16, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { u32, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { u64, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { u128, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { usize, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { i8, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { i16, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { i32, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { i64, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { i128, #[stable(feature = "from_bool", since = "1.28.0")] }
impl_from_bool! { isize, #[stable(feature = "from_bool", since = "1.28.0")] }

// Unsigned -> Unsigned
impl_from! { u8, u16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
Expand Down