RandomEngine instances are consumed by random_normal() and random_uniform()

[maddiemort]

I'm not sure if I'm fully understanding the way the Rust wrapper interacts with the C API, but it seems strange/inconvenient to me that random_normal() and random_uniform() consume instances of RandomEngine rather than taking a &RandomEngine or a &mut RandomEngine. For example:

extern crate arrayfire;
extern crate time;

use arrayfire::*;

fn foo() {
    let now = time::get_time().sec as u64;
    let random_engine = RandomEngine::new(RandomEngineType::PHILOX_4X32_10, Some(now));

    let dims = Dim4::new(&[4, 1, 1, 1]);

    let rand1 = random_normal::<f32>(dims,
        random_engine // `random_engine` is moved here
    ); 
    
    let rand2 = random_normal::<f32>(dims,
        random_engine // `random_engine` can't be used here, because it's been moved
    );
}

In that example, random_engine is moved by the first call to random_normal(), so it can't be used again in the second call. Replacing random_engine with random_engine.clone() fixes this, but it seems strange that that needs to be explicitly called. Am I misunderstanding how the Rust wrapper works, or would it make sense either for RandomEngine (because it is simply a wrapper around an FFI handle) to #[derive(Copy)] or for random_normal() and random_uniform() to be declared as follows?

pub fn random_uniform<T: HasAfEnum>(dims: Dim4, engine: &RandomEngine) -> Array { /* ... */ }
pub fn random_normal<T: HasAfEnum>(dims: Dim4, engine: &RandomEngine) -> Array { /* ... */ }
//            A shared reference rather than ownership ^^^^^^^^^^^^^

[maddiemort]

Any update on this? Thanks.

[9prady9]

Sorry about the delay. Haven't been able to look into it until now. Firstly, RandomEngine is a wrapper around C-pointer/handle, thus I had to implement Drop trait on the struct to properly clean up the resource. Once we did that, we couldn't implement Copy trait as that is not allowed. That is the reason, we can't do #[derive(Copy)].

As far as why I wasn't borrowing RandomEngine instead of moving, I think I got it wrong. Borrowing seems more right instead of moving. I see that you have raised the PR. Thank you for that.