Allow an AffineTransform to be constructed from a borrowed array

[urschrei]

• I agree to follow the project's code of conduct.
• I added an entry to CHANGES.md if knowledge of this change could be valuable to users.

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"borrowed array" was formerly "slice", which was wrong!

[lnicola]

That's not a slice, is it?

[urschrei]

Well this is embarrassing

[urschrei]

how about now?

[lnicola]

Better. This could probably be A: AsRef<[T; 6]>, but whatever.

Still, as prior art, Ipv4Addr only implements From<[u8; 4]>. And [T; 6] will be Copy, so I'm not sure it's worth adding it.

[urschrei]

Better. This could probably be A: AsRef<[T; 6]>, but whatever.

I actually tried this but got the annoying trait objects must include the dyn keyword error, which also doesn't help since the compiler says dyn AsRef<[T; 6]> + 'static doesn't impl Sized. I gave up at that point, rightly or wrongly.

[lnicola]

I meant

impl<T: CoordNum, A: AsRef<[T; 6]>> From<A> for AffineTransform<T> {
    fn from(arr: A) -> Self {
        let arr = arr.as_ref();
        Self::new(arr[0], arr[1], arr[2], arr[3], arr[4], arr[5])
    }
}

This would subsume both existing implementations ([T; 6] and (T, T, T, T, T, T)), as well as the one for &[T; 6].

But as I mentioned, I don't think it's necessary. Do you have some example where it helps? Because the following already works today:

fn foo(arr: &[f64; 6]) {
    let _tr = AffineTransform::from(*arr);
}

[urschrei]

Do you have some example where it helps? Because the following already works today

Only in avoiding the *, which was annoying me…

[urschrei]

But maybe your AsRef is the way to go.

[lnicola]

Dunno, if From<[u8; 4]> is good enough for the standard library, maybe it's good enough for us? 🙂.

[urschrei]

Fair.

[frewsxcv]

#1149