📜 Contexts and capabilities Charter

Context objects in Rust must be passed manually today. This means that they are difficult or impossible to use with code you don't control. It also pushes programmers toward making context objects more coarse-grained than they have to be and using globals where they aren't desirable.

The goal of this initiative is to create a first-class way of working with contexts in Rust that solves these problems:

• It should be possible to thread contexts through code you don't control, without the code having to make any accommodations.
• Contexts are allowed to exist on the stack.
• Contexts can be generic / type erased.
• Contexts can be "decomposed" into smaller pieces or "bundled" into larger ones.
• Contexts can be used to implement compile-time dependency injection.
• Contexts work well with dyn, higher order functions, and the like.

Eventually this mechanism can be used to solve a number of other challenges in the language and standard library:

• Making "global" objects like allocators and async executors defineable and overridable by the user.
• Describing one's runtime environment in a more detailed way than core/alloc/std, which is not always appropriate for runtimes like wasm.
• Making the Rust ecosystem more composable and interoperable.

Proposal

TODO

Membership