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Remove description of export, briefly describe pub use.

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Graydon Hoare 2012-09-26 10:51:01 -07:00
parent 385c4dfba0
commit fbf362809b
1 changed files with 14 additions and 86 deletions
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doc/rust.md
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@ -783,9 +783,8 @@ link_attrs : link_attr [ ',' link_attrs ] + ;
link_attr : ident '=' literal ;
~~~~~~~~
An _extern mod declaration_ specifies a dependency on an external crate. The
external crate is then imported into the declaring scope as the `ident`
provided in the `extern_mod_decl`.
An _extern mod declaration_ specifies a dependency on an external crate.
The external crate is then bound into the declaring scope as the `ident` provided in the `extern_mod_decl`.
The external crate is resolved to a specific `soname` at compile time, and a
runtime linkage requirement to that `soname` is passed to the linker for
@ -825,16 +824,16 @@ linkage-dependency with external crates. Linkage dependencies are
independently declared with
[`extern mod` declarations](#extern-mod-declarations).
Imports support a number of "convenience" notations:
Use declarations support a number of "convenience" notations:
* Importing as a different name than the imported name, using the
* Rebinding the target name as a new local name, using the
syntax `use x = p::q::r;`.
* Importing a list of paths differing only in final element, using
the glob-like brace syntax `use a::b::{c,d,e,f};`
* Importing all paths matching a given prefix, using the glob-like
asterisk syntax `use a::b::*;`
* Simultaneously binding a list of paths differing only in final element,
using the glob-like brace syntax `use a::b::{c,d,e,f};`
* Binding all paths matching a given prefix,
using the glob-like asterisk syntax `use a::b::*;`
An example of imports:
An example of `use` declarations:
~~~~
use foo = core::info;
@ -855,82 +854,11 @@ fn main() {
}
~~~~
##### Export declarations
~~~~~~~~ {.ebnf .gram}
export_decl : "export" ident [ ',' ident ] *
| "export" ident "::{}"
| "export" ident '{' ident [ ',' ident ] * '}' ;
~~~~~~~~
An _export declaration_ restricts the set of local names within a module that
can be accessed from code outside the module. By default, all _local items_ in
a module are exported; imported paths are not automatically re-exported by
default. If a module contains an explicit `export` declaration, this
declaration replaces the default export with the export specified.
An example of an export:
~~~~~~~~
pub mod foo {
#[legacy_exports];
export primary;
fn primary() {
helper(1, 2);
helper(3, 4);
}
fn helper(x: int, y: int) {
...
}
}
fn main() {
foo::primary(); // Will compile.
}
~~~~~~~~
If, instead of calling `foo::primary` in main, you were to call `foo::helper`
then it would fail to compile:
~~~~~~~~{.ignore}
foo::helper(2,3) // ERROR: will not compile.
~~~~~~~~
Multiple names may be exported from a single export declaration:
~~~~~~~~
mod foo {
export primary, secondary;
fn primary() {
helper(1, 2);
helper(3, 4);
}
fn secondary() {
...
}
fn helper(x: int, y: int) {
...
}
}
~~~~~~~~
When exporting the name of an `enum` type `t`, by default, the module does
*not* implicitly export any of `t`'s constructors. For example:
~~~~~~~~
mod foo {
export t;
enum t {a, b, c}
}
~~~~~~~~
Here, `foo` imports `t`, but not `a`, `b`, and `c`.
Like items, `use` declarations are private to the containing module, by default.
Also like items, a `use` declaration can be public, if qualified by the `pub` keyword.
A public `use` declaration can therefore be used to _redirect_ some public name to a different target definition,
even a definition with a private canonical path, inside a different module.
If a sequence of such redirections form a cycle or cannot be unambiguously resolved, they represent a compile-time error.
### Functions