Support bang-bang methods for `StaticArrays`

[rveltz]

Hi!

Is it expected!

using StaticArrays, VectorInterface

julia> scale!!(SVector(1.,1.), 1.)
ERROR: setindex!(::SVector{2, Float64}, value, ::Int) is not defined.
 Hint: Use `MArray` or `SizedArray` to create a mutable static array
Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] setindex!(a::SVector{2, Float64}, value::Float64, i::Int64)
    @ StaticArrays ~/.julia/packages/StaticArrays/DsPgf/src/indexing.jl:3
  [3] macro expansion
    @ ~/.julia/packages/StaticArrays/DsPgf/src/broadcast.jl:159 [inlined]
  [4] _broadcast!

[Jutho]

Not really. It seems our general AbstractArray implementation of scale!! assumes arrays to be mutable. I am happy to see this changed.

[Jutho]

Thinking some more about this, it would actually be quite annoying if our generic assumption is that AbstractArray instances are not mutable, as the majority of them are. I think we will need a package extension for StaticArrays.jl in order to support this.

[rveltz]

Hi!

Do you have time to write such extension?

[lkdvos]

Sorry for taking a bit of time to get to this, this only just came to my attention.
If you could let me know if this know behaves as you would expect, that would be great!

[rveltz]

Thank you for looking into this.
It seems to behave like "I want".