mozilla/rust — pull request #14427 by alexcrichton (2014-05-25 20:50:24+00:00)
Title: std: Recreate a `rand` module

This commit shuffles around some of the `rand` code, along with some
reorganization. The new state of the world is as follows:

* The librand crate now only depends on libcore. This interface is experimental.
* The standard library has a new module, `std::rand`. This interface will
eventually become stable.

Unfortunately, this entailed more of a breaking change than just shuffling some
names around. The following breaking changes were made to the rand library:

* Rng::gen_vec() was removed. This has been replaced with Rng::gen_iter() which
will return an infinite stream of random values. Previous behavior can be
regained with `rng.gen_iter().take(n).collect()`

* Rng::gen_ascii_str() was removed. This has been replaced with
Rng::gen_ascii_chars() which will return an infinite stream of random ascii
characters. Similarly to gen_iter(), previous behavior can be emulated with
`rng.gen_ascii_chars().take(n).collect()`

* {IsaacRng, Isaac64Rng, XorShiftRng}::new() have all been removed. These all
relied on being able to use an OSRng for seeding, but this is no longer
available in librand (where these types are defined). To retain the same
functionality, a new method, reseed_rng, was added to the SeedableRng trait.
This method will seed the current RNG from another RNG. This allows the stdlib
to define the OSRng which is used to seed instances of all these other RNGs.

* Rand implementations for `Box` and `@T` were removed. These seemed to be
pretty rare in the codebase, and it allows for libcore to not depend on
liballoc. Additionally, other pointer types like Rc and Arc were not
supported. If this is undesirable, librand can depend on liballoc and regain
these implementations.

* The WeightedChoice structure is no longer built with a `Vec>`,
but rather a `&mut [Weighted]`. This means that the WeightedChoice
structure now has a lifetime associated with it.

cc #13851

[breaking-change]