generic_singleton

Rust does NOT monomorphize it's [static generic items]. This means you cannot use a generic static item in a generic function. You'll get the following error: text error[E0401]: can't use generic parameters from outer function

That's pretty frustrating when you want to write a singleton pattern that rely's on a generic parameter. This crate allows for this pattern with minimal runtime overhead.

generic_singleton uses [anymap] behind the scenes to store a map of each generic type. The first time you hit the get_or_init macro we initialize the singleton. Subsequent calls to get_or_init will retrieve the singleton from the map.

Example

```rust use std::{cell::RefCell, ops::AddAssign};

use num_traits::{One, Zero};

fn genericcallcounter() -> T { let mut count = genericsingleton::getorinit!(|| RefCell::new(T::zero())).borrowmut(); *count += T::one(); *count }

fn main() { // Works with usize asserteq!(genericcallcounter::(), 1); asserteq!(genericcallcounter::(), 2); asserteq!(genericcall_counter::(), 3);

// Works with i32
assert_eq!(generic_call_counter::<i32>(), 1);
assert_eq!(generic_call_counter::<i32>(), 2);
assert_eq!(generic_call_counter::<i32>(), 3);

// Works with f32
assert_eq!(generic_call_counter::<f32>(), 1.0);
assert_eq!(generic_call_counter::<f32>(), 2.0);
assert_eq!(generic_call_counter::<f32>(), 3.0);

} ```

Current limitations:

• The map is guarded by an RwLock for thread-safety. This is unnecessary in single-threaded situations.