I am glad to get two consistent answers within 1 minute of each other!
On Wednesday, April 13, 2016 at 1:48:20 PM UTC-4, Matt Bauman wrote:
>
> If you're able to define a `size` method for the Associative types, then
> I'd call them all AbstractArrays.
>
Yeah they are 1 dimensional and have size(A) = n. I am thinking that it is
0 on every index that hasn't been set yet, and the only valid indices are i
in 1:n.
I want to use Dict{Int,T} as a "lazily allocated" Vector{T}.
> I'd use a wrapper type like the last example in
> http://docs.julialang.org/en/release-0.4/manual/interfaces/#abstract-arrays.
> You could parameterize the `data` field so any associative type could be
> wrapped. As a bonus: now it works like an array in Base code, too, without
> changing any signatures.
>
So the SparseArray in the example would become
immutable SparseArray{C<:Associative{N, T},T,N} <: AbstractArray{T,N}
data::C
dims::N
end
And then all my functions that currently use Array{T,N} can use
AbstractArray{T,N} and then can use this SparseArray automagically?
This gives an error
ERROR: UndefVarError: N not defined
immutable SparseArray2{C<:Associative,T,N} <: AbstractArray{T,N}
data::C
dims::NTuple{N,Int}
end
Works but then when constructing it you need to make sure that C, T, and N
are consistent in the constructor logic because there is nothing in the
type definition that would forbid you from instantiating a
SparseArray2{Dict{Int, Float64}, Float32, 3}(Dict{Int, Float64}(), (2,3,4))
The problem is that data is not an Associative{NTuple{N, Int}, T}.
Is there any way to specify this in the Type definitions?
Or do you make a constructor that validates C <: Associative{NTuple{N,
Int},T} at construction time?
What would be the appropriate error to throw in this case?
Thanks,
James
