add default constructors for AbstractRange

[putianyi889]

Related posts

• Support convert(AbstractArray{T}, ::AbstractRange) and variants #27138
• Implement AbstractVector{T}(r::AbstractRange), fix #27138 #28956

[inkydragon]

Is it necessary to add constructors for abstract types?

julia> methods(AbstractRange)
# 0 methods for type constructor

julia> supertype(AbstractRange)
AbstractVector (alias for AbstractArray{T, 1} where T)

julia>  methods(AbstractVector)
# 0 methods for type constructor

julia> supertype(AbstractVector)
Any

[putianyi889]

As you can see from added tests, it does eltype conversion for general ranges.
AbstractArray has constructors.

[jishnub]

@putianyi889 This seems like a good idea. Is this ready from your side?
We would probably want more tests.

[putianyi889]

Is this ready from your side?

confirm.

We would probably want more tests.

not sure how many. maybe add 2-3 segments to every conversion test?

[jishnub]

Could you add tests for other range types, such as StepRangeLen and StepRange, including cases where the elements are floating-point types?

[putianyi889]

There are some issues with the step type of OrdinalRange, but I think that should be addressed in another issue.

[putianyi889]

Found this

julia/base/abstractarray.jl

Lines 1237 to 1244 in 7635190

	## range conversions ##
	map(::Type{T}, r::StepRange) where {T<:Real} = T(r.start):T(r.step):T(last(r))
	map(::Type{T}, r::UnitRange) where {T<:Real} = T(r.start):T(last(r))
	map(::Type{T}, r::StepRangeLen) where {T<:AbstractFloat} = convert(StepRangeLen{T}, r)
	function map(::Type{T}, r::LinRange) where T<:AbstractFloat
	LinRange(T(r.start), T(r.stop), length(r))
	end