Support iter_mut() for FlatArray<'mcx, T: Sized>?

[my-vegetable-has-exploded]

I think it is helpful to support iter_mut() for pgrx::Array.
For aggregate state including pgrx::Array , support iter_mut() for pgrx::Array will make it possible to reuse to old state.

[workingjubilee]

@my-vegetable-has-exploded It is not possible for all T. Some T are unsized so you cannot iteratively mutate them in a sensible way.

And it is not currently possible at all for Array<'a, T> because it is an explicitly "borrowed" form, i.e. it's always effectively Array<&T>. I am working on a FlatArray<'a, T: ?Sized> which can support this, by allowing &FlatArray and &mut FlatArray.

[workingjubilee]

@my-vegetable-has-exploded I'm curious what kind of mutation you were hoping to do, exactly? It might be better for this to be modeled via an impl Write.

[my-vegetable-has-exploded]

My goal is to write a aggregate function sfunc( internal-state, next-data-values ) ---> next-internal-state. I use a fixed sized Array as part of state, and I'd like to modify elements in-place (just add, like state[i] += data[i]). In my opinion， support iter_mut() will help a lot.
Thanks @workingjubilee

[workingjubilee]

Ah okay, so you want integers and floats. Sure!

[workingjubilee]

Hm. Something that looks like "mutable iteration" of TEXT[] would require a Scan-like functionality, where you buffer the state of the current/next string, or a functionality to use the "Expanded" array repr.

[my-vegetable-has-exploded]

Hm. Something that looks like "mutable iteration" of TEXT[] would require a Scan-like functionality, where you buffer the state of the current/next string, or a functionality to use the "Expanded" array repr.

Sorry, I don't quite sure the point of this paragraph. If there is anything I can do to help, please tell me.