Oops!
Many thanks
Leonardo
Il giorno martedì 15 settembre 2015 12:32:02 UTC+2, Tim Holy ha scritto:
>
> `next` requires a second argument, the `state` variable. Your code doesn't
> pass a second argument, which is why you're getting the error.
>
> --Tim
>
> On Tuesday, September 15, 2015 08:18:09 AM Leonardo wrote:
> > Sorry,
> > but now I have some doubt relative to concatenation for my redefined
> Array.
> >
> > In my exampled (attached) I've redefined AbstractArray creating a simple
> > container for an Array, and I redefined also start() / next() / done()
> > calling same operations for internal Array, but in following few lines
> > of code:
> >
> > a = MyArr{2}(1,2)
> > a[1,1] = "hello"
> > a[1,2] = "world"
> > cat(1, a, ["bob" "alice"])
> >
> > cat() fails with following error:
> >
> > ERROR: MethodError: `next` has no method matching
> > next(::Array{AbstractString,2})
> > Closest candidates are:
> > next(::Array{T,N}, ::Any)
> > next(::AbstractArray{T,N}, ::Any)
> > in _unsafe_batchsetindex! at multidimensional.jl:328
> > in setindex! at abstractarray.jl:572
> > in cat_t at abstractarray.jl:840
> > in vcat at abstractarray.jl:861
> >
> > Anyone can indicate me what MUST be reimplemented for AbstractArray{T,N}
> > to support concatenation operations?
> >
> > Many thanks in advance
> >
> > Leonardo
> >
> > Il 13/09/2015 09:48, Leonardo ha scritto:
> > > Many thanks!
> > > I've understood that parametric type and number of dimension are
> > > necessary, then I can write something like:
> > > type MyArr{N} <: AbstractArray{String,N}
> > > ...
> > > end
> > >
> > > but, cause I want constructor receives the range of components for
> > > each dimension like:
> > > a = MyArr{3}(2,3,4)
> > > I MUST ensure that parametric dimension be consistent with passed
> > > number of indexes, highlighting (with an Error) that forms like:
> > > a = MyArr{3}(2,3)
> > > are illegal (see my attached example)
> > >
> > > (maybe OT: I think that using Integer as Type Parameter is a bit
> > > confusing for people like me that have developed by many year in other
> > > languages with generics as Java, C++, C# because use of a
> > > object-parameter opposed to conventional type-parameter is a bit odd;
> > > see also
> https://groups.google.com/forum/#!topic/julia-users/3NM7tZV5buQ )
> > >
> > > Leonardo
> > >
> > > P.S. surprisingly chapters
> > > http://docs.julialang.org/en/release-0.4/manual/interfaces/ and
> > > http://docs.julialang.org/en/latest/manual/interfaces/ are
> unavailable
> > > into relative PDFs on readthedocs.org
> > >
> > > Il 11/09/2015 14:46, Matt Bauman ha scritto:
> > >> On Friday, September 11, 2015 at 3:11:48 AM UTC-4, Leonardo wrote:
> > >> I like to have a /unique/ type that contains only a specified
> > >> type and that can handle any dimension, but only during object
> > >> instancing (not during subsequent lifecycle of object, also if
> > >> both phases are at runtime), than parametrized dimension (the
> > >> N in AbstractArray{T,N}) is not useful for me.
> > >>
> > >> You can have a constructor that deals with the parameter for you:
> > >>
> > >> MyArr(number_of_dimensions::Int) = MyArr{Any, number_of_dimensions}()
> > >>
> > >> I'm afraid I still don't understand why you want to do this, so my
> > >> answers probably aren't all that helpful.
> > >>
> > >> But - if I understood your indications - there is no way to do
> > >> this without redefine a bunch of methods.
> > >> At least, can I find somewhere a minimal list of these methods?
> > >>
> > >> That's correct. Omitting the dimensionality isn't a supported way to
> > >> subtype AbstractArray. I suppose you can still do it, but being
> > >> unsupported means that you're on your own to figure out what all
> > >> needs to be re-implemented. And unfortunately, I'm afraid that the
> > >> list isn't so minimal. It's a part of the AbstractArray definition
> > >> that is very heavily leveraged in the base code to improve
> > >> performance and specify behavior.
> > >>
> > >> You can start to get a sense of how heavily these parameters are used
> > >> by looking at the methods defined for AbstractArray{T,1}
> > >> (AbstractVector) and AbstractArray{T,2} (AbstractMatrix):
> > >>
> > >> julia> methodswith(AbstractVector)
> > >> 151-element Array{Method,1}: …
> > >>
> > >> julia> methodswith(AbstractMatrix)
> > >> 164-element Array{Method,1}: …
> > >>
> > >> Those don't even include methods defined for arbitrary dimensionality
> > >> but still require N to be defined, like
> > >> `ndims{T,N}(A::AbstractArray{T,N}) = N`.
>
>
