[CustomView Error] Multiple views of the same storage ...

[PudgeKim]

I created some custom view which takes EntitiesViewMut, UniqueView, UniqueViewMut, View and ViewMut. so it's ViewBundle.

I got an error below.

Multiple views of the same storage including an exclusive borrow, consider removing the shared borrow.

Should I split it to four custom view? or Is there other nice way to do?

[leudz]

You can't take a UniqueView and UniqueViewMut of the same component at the same time. The is also the case for View/ViewMut. The error suggests to not borrow the shared view (UniqueView/View) since you can read from an exclusive view.

Should I split it to four custom view? or Is there other nice way to do?

It depends on what you are trying to do.

[leudz]

Yes, even if you split it in two you would still have access to both at the same time and it's not possible. It's the main rule of the borrow checker. If you try with u32 for example:

fn borrow(immutable: &u32, mutable: &mut u32) {}

let mut i = 0;
borrow(&i, &mut i);

you'll get this error:

cannot borrow `i` as mutable because it is also borrowed as immutable

Shipyard moves the borrow check to runtime but the same rules apply.

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The split MyView/MyViewMut makes sense to me but why do you want to get both at the same time? MyViewMut should be able to do everything MyView can do and more.

[PudgeKim]

I deleted the post by mistake. yeah I need to change all View to ViewMut. thank you.