typemap-meta

Crates.io Docs.rs Build Status

An Enlightware® software.

Overview

A simple compile-time (hence the meta) derive macro to create type-to-value maps (hence the typemap). This approach in contrast to crates such as typemap or type-map that perform run-time lookup. The static typing brings compile-time safety and faster execution at the expense of using a derive macro and generics.

The crate is no_std compatible.

Usage

To use this crate, first add this to your Cargo.toml:

toml [dependencies] typemap-meta = "0.2"

Then, you can create a tuple struct containing disjoint heterogeneous types, and derive Typemap, and then use the get! macro (a syntactic sugar around Typemap::Get):

```rust

[derive(Typemap)]

struct Test(i32, f32); let t = Test(1, 2.0); asserteq!(*get!(t, i32), 1); asserteq!(*get!(t, f32), 2.0); ```

A mutable version is also available:

```rust

[derive(Typemap)]

[typemap_mut]

struct Test(i32, f32); let mut t = Test(1, 2.0); get_mut!(t, i32) = 3; *get_mut!(t, f32) = 4.0; assert_eq!(get!(t, i32), 3); assert_eq!(*get!(t, f32), 4.0); ```

Crate structure

As currently procedural macros must be defined in their own crate, we have two crates typemap-meta and typemap-meta-derive, the former re-exporting the macro from the later. Only the former needs to be imported in your project.

License

Licensed under either of

at your option.