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Add inline attributes documentation.

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Closes #7959.
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William Ting 2014-01-11 22:01:55 -06:00
parent a34727f276
commit 826f24bdf1
1 changed files with 28 additions and 6 deletions
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34
doc/rust.md
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@ -1215,7 +1215,7 @@ A static item must have a _constant expression_ giving its definition.
Static items must be explicitly typed.
The type may be ```bool```, ```char```, a number, or a type derived from those primitive types.
The derived types are references with the `'static` lifetime,
The derived types are references with the `static` lifetime,
fixed-size arrays, tuples, and structs.
~~~~
@ -1730,14 +1730,17 @@ names are effectively reserved. Some significant attributes include:
* The `doc` attribute, for documenting code in-place.
* The `cfg` attribute, for conditional-compilation by build-configuration.
* The `lang` attribute, for custom definitions of traits and functions that are known to the Rust compiler (see [Language items](#language-items)).
* The `link` attribute, for describing linkage metadata for a extern blocks.
* The `crate_id` attribute, for describing the package ID of a crate.
* The `lang` attribute, for custom definitions of traits and functions that are
known to the Rust compiler (see [Language items](#language-items)).
* The `link` attribute, for describing linkage metadata for a extern blocks.
* The `test` attribute, for marking functions as unit tests.
* The `allow`, `warn`, `forbid`, and `deny` attributes, for
controlling lint checks (see [Lint check attributes](#lint-check-attributes)).
* The `deriving` attribute, for automatically generating
implementations of certain traits.
* The `inline` attribute, for expanding functions at caller location (see
[Inline attributes](#inline-attributes)).
* The `static_assert` attribute, for asserting that a static bool is true at compiletime
* The `thread_local` attribute, for defining a `static mut` as a thread-local. Note that this is
only a low-level building block, and is not local to a *task*, nor does it provide safety.
@ -1910,6 +1913,25 @@ A complete list of the built-in language items follows:
> **Note:** This list is likely to become out of date. We should auto-generate it
> from `librustc/middle/lang_items.rs`.
### Inline attributes
The inline attribute is used to suggest to the compiler to perform an inline
expansion and place a copy of the function in the caller rather than generating
code to call the function where it is defined.
The compiler automatically inlines functions based on internal heuristics.
Incorrectly inlining functions can actually making the program slower, so it
should be used with care.
`#[inline]` and `#[inline(always)]` always causes the function to be serialized
into crate metadata to allow cross-crate inlining.
There are three different types of inline attributes:
* `#[inline]` hints the compiler to perform an inline expansion.
* `#[inline(always)]` asks the compiler to always perform an inline expansion.
* `#[inline(never)]` asks the compiler to never perform an inline expansion.
### Deriving
The `deriving` attribute allows certain traits to be automatically
@ -3223,12 +3245,12 @@ The type of a closure mapping an input of type `A` to an output of type `B` is `
An example of creating and calling a closure:
```rust
let captured_var = 10;
let captured_var = 10;
let closure_no_args = || println!("captured_var={}", captured_var);
let closure_no_args = || println!("captured_var={}", captured_var);
let closure_args = |arg: int| -> int {
println!("captured_var={}, arg={}", captured_var, arg);
println!("captured_var={}, arg={}", captured_var, arg);
arg // Note lack of semicolon after 'arg'
};