This commit adds stability markers for the APIs that have recently been
aligned with [numerics
reform](https://github.com/rust-lang/rfcs/pull/369). For APIs that were
changed as part of that reform, `#[unstable]` is used to reflect the
recency, but the APIs will become `#[stable]` in a follow-up pass.
In addition, a few aspects of the APIs not explicitly covered by the RFC
are marked here -- in particular, constants for floats.
This commit does not mark the `uint` or `int` modules as `#[stable]`,
given the ongoing debate out the names and roles of these types.
Due to some deprecation (see the RFC for details), this is a:
[breaking-change]
`slice_shift_char` splits a `str` into it's leading `char` and the remainder of the `str`. Currently, it returns a `(Option<char>, &str)` such that:
"bar".slice_shift_char() => (Some('b'), "ar")
"ar".slice_shift_char() => (Some('a'), "r")
"r".slice_shift_char() => (Some('r'), "")
"".slice_shift_char() => (None, "")
This is a little odd. Either a `str` can be split into both a head and a tail or it cannot. So the return type should be `Option<(char, &str)>`. With the current behaviour, in the case of the empty string, the `str` returned is meaningless - it is always the empty string.
This PR changes `slice_shift_char` so that:
"bar".slice_shift_char() => Some(('b', "ar"))
"ar".slice_shift_char() => Some(('a', "r"))
"r".slice_shift_char() => Some(('r', ""))
"".slice_shift_char() => None
This breaks code that referred to variant names in the same namespace as
their enum. Reexport the variants in the old location or alter code to
refer to the new locations:
```
pub enum Foo {
A,
B
}
fn main() {
let a = A;
}
```
=>
```
pub use self::Foo::{A, B};
pub enum Foo {
A,
B
}
fn main() {
let a = A;
}
```
or
```
pub enum Foo {
A,
B
}
fn main() {
let a = Foo::A;
}
```
[breaking-change]
`slice_shift_char` splits a `str` into it's leading `char` and the remainder
of the `str`. Currently, it returns a `(Option<char>, &str)` such that:
"bar".slice_shift_char() => (Some('b'), "ar")
"ar".slice_shift_char() => (Some('a'), "r")
"r".slice_shift_char() => (Some('r'), "")
"".slice_shift_char() => (None, "")
This is a little odd. Either a `str` can be split into both a head and a
tail or it cannot. So the return type should be `Option<(char, &str)>`.
With the current behaviour, in the case of the empty string, the `str`
returned is meaningless - it is always the empty string.
This commit changes slice_shift_char so that:
"bar".slice_shift_char() => Some(('b', "ar"))
"ar".slice_shift_char() => Some(('a', "r"))
"r".slice_shift_char() => Some(('r', ""))
"".slice_shift_char() => None
[breaking-change]
Previously Int inherited from PartialOrd (via Primitive)
but not Ord. But integers have a total order, so
inheriting from Ord is appropriate. Fixes#18776.
https://github.com/rust-lang/rfcs/pull/221
The current terminology of "task failure" often causes problems when
writing or speaking about code. You often want to talk about the
possibility of an operation that returns a Result "failing", but cannot
because of the ambiguity with task failure. Instead, you have to speak
of "the failing case" or "when the operation does not succeed" or other
circumlocutions.
Likewise, we use a "Failure" header in rustdoc to describe when
operations may fail the task, but it would often be helpful to separate
out a section describing the "Err-producing" case.
We have been steadily moving away from task failure and toward Result as
an error-handling mechanism, so we should optimize our terminology
accordingly: Result-producing functions should be easy to describe.
To update your code, rename any call to `fail!` to `panic!` instead.
Assuming you have not created your own macro named `panic!`, this
will work on UNIX based systems:
grep -lZR 'fail!' . | xargs -0 -l sed -i -e 's/fail!/panic!/g'
You can of course also do this by hand.
[breaking-change]
At the moment, writing generic functions for integer types that involve shifting is rather verbose. For example, a function at shifts an integer left by 1 currently requires
use std::num::One;
fn f<T: Int>(x : T) -> T {
x << One::one()
}
If the shift amount is not 1, it's even worse:
use std::num::FromPrimitive;
fn f<T: Int + FromPrimitive>(x: T) -> T {
x << FromPrimitive::from_int(2).unwrap()
}
This patch allows the much simpler implementation
fn f<T: Int>(x: T) -> T {
x << 2
}
It accomplishes this by changing the built-in integer types (and the `Int` trait) to implement `Shl<uint, T>` instead of `Shl<T, T>` as it currently is defined. Note that the internal implementations of `shl` already cast the right-hand side to `uint`. `BigInt` also implements `Shl<uint, BigInt>`, so this increases consistency.
All of the above applies similarly to right shifts, i.e., `Shr<uint, T>`.
