Return an AbstractFill from view?

[tkf]

As it is planned to return an AbstractRange from view(::AbstractRange, ...) JuliaLang/julia#26872, I think similarly it makes sense to return an AbstractFill from view(::AbstractFill, ...). I think it is also compatible with reshape(::AbstractFill, ...) :: AbstractFill. What do you think?

[dlfivefifty]

Ha I came across this issue and was planning to propose this change. I think this is a great idea.

[dlfivefifty]

I worked around this in LazyArrays.jl: https://github.com/JuliaArrays/LazyArrays.jl/blob/42823c66a0344f61fafab1da96db5260079afd36/src/lazybroadcasting.jl#L213

But still preferable to overload view as you suggest.

[dlfivefifty]

Ha, just deleted a long post why this is a bad idea because range doesn't do it when I noticed range does!

julia> view(1:5, 1:3)
1:3

That said, #125 makes me hesitant that downstream packages will assume that view returns a SubArray, or at the very least something that satisfies the implicit subarray interface, e.g.

v == parent(v)[parentindices(v)...]

In fact the docs for view hint strongly that this is required:

Like getindex, but returns a view into the parent array A with the given
indices instead of making a copy
Since this is inconsistent with the behaviour of ranges I'm going to make a PR to alter the docs for view.

[dlfivefifty]

This has been implemented.