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This is based off of @blake2-ppc's work on #9429. That PR bitrotted and I haven't been able to contact the original author so I decided to take up the cause. Overview ====== `Mut` encapsulates a mutable, non-nullable slot. The `Cell` type is currently used to do this, but `Cell` is much more commonly used as a workaround for the inability to move values into non-once functions. `Mut` provides a more robust API. `Mut` duplicates the semantics of borrowed pointers with enforcement at runtime instead of compile time. ```rust let x = Mut::new(0); { // make some immutable borrows let p = x.borrow(); let y = *p.get() + 10; // multiple immutable borrows are allowed simultaneously let p2 = x.borrow(); // this would throw a runtime failure // let p_mut = x.borrow_mut(); } // now we can mutably borrow let p = x.borrow_mut(); *p.get() = 10; ``` `borrow` returns a `Ref` type and `borrow_mut` returns a `RefMut` type, both of which are simple smart pointer types with a single method, `get`, which returns a reference to the wrapped data. This also allows `RcMut<T>` to be deleted, as it can be replaced with `Rc<Mut<T>>`. Changes ====== I've done things a little bit differently than the original proposal. * I've added `try_borrow` and `try_borrow_mut` methods that return `Option<Ref<T>>` and `Option<RefMut<T>>` respectively instead of failing on a borrow check failure. I'm not totally sure when that'd be useful, but I don't see any reason to not put them in and @cmr requested them. * `ReadPtr` and `WritePtr` have been renamed to `Ref` and `RefMut` respectively, as `Ref` is to `ref foo` and `RefMut` is to `ref mut foo` as `Mut` is to `mut foo`. * `get` on `MutRef` now takes `&self` instead of `&mut self` for consistency with `&mut`. As @alexcrichton pointed, out this violates soundness by allowing aliasing `&mut` references. * `Cell` is being left as is. It solves a different problem than `Mut` is designed to solve. * There are no longer methods implemented for `Mut<Option<T>>`. Since `Cell` isn't going away, there's less of a need for these, and I didn't feel like they provided a huge benefit, especially as that kind of `impl` is very uncommon in the standard library. Open Questions ============ * `Cell` should now be used exclusively for movement into closures. Should this be enforced by reducing its API to `new` and `take`? It seems like this use case will be completely going away once the transition to `proc` and co. finishes. * Should there be `try_map` and `try_map_mut` methods along with `map` and `map_mut`? |
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The Rust Programming Language
This is a compiler for Rust, including standard libraries, tools and documentation.
Quick Start
Windows
Note: Windows users should read the detailed getting started notes on the wiki. Even when using the binary installer the Windows build requires a MinGW installation, the precise details of which are not discussed here.
Linux / OS X
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Install the prerequisites (if not already installed)
- g++ 4.4 or clang++ 3.x
- python 2.6 or later (but not 3.x)
- perl 5.0 or later
- gnu make 3.81 or later
- curl
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Download and build Rust You can either download a tarball or build directly from the repo.
To build from the tarball do:
$ curl -O http://static.rust-lang.org/dist/rust-0.8.tar.gz $ tar -xzf rust-0.8.tar.gz $ cd rust-0.8Or to build from the repo do:
$ git clone https://github.com/mozilla/rust.git $ cd rustNow that you have Rust's source code, you can configure and build it:
$ ./configure $ make && make installYou may need to use
sudo make installif you do not normally have permission to modify the destination directory. The install locations can be adjusted by passing a--prefixargument toconfigure. Various other options are also supported, pass--helpfor more information on them.When complete,
make installwill place several programs into/usr/local/bin:rustc, the Rust compiler;rustdoc, the API-documentation tool, andrustpkg, the Rust package manager and build system. -
Read the tutorial.
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Enjoy!
Notes
Since the Rust compiler is written in Rust, it must be built by a precompiled "snapshot" version of itself (made in an earlier state of development). As such, source builds require a connection to the Internet, to fetch snapshots, and an OS that can execute the available snapshot binaries.
Snapshot binaries are currently built and tested on several platforms:
- Windows (7, Server 2008 R2), x86 only
- Linux (various distributions), x86 and x86-64
- OSX 10.6 ("Snow Leopard") or greater, x86 and x86-64
You may find that other platforms work, but these are our "tier 1" supported build environments that are most likely to work.
Rust currently needs about 1.8G of RAM to build without swapping; if it hits swap, it will take a very long time to build.
There is lots more documentation in the wiki.
License
Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.
See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.