Thanks for those useful hints!
On Monday, February 15, 2016 at 2:49:04 PM UTC+1, Tim Holy wrote:
>
> True, but when you care about performance it's much better to write the
> wrapper functions---the results will be inferrable, unlike manipulations
> of
> the parameters vector.
>
> For Arrays, you already have the defined function `eltype` and `ndims`. If
> your
> types fall into some kind of hierarchy, then you may be able to use
> subtyping.
> For example:
>
> julia> immutable MyWeirdArray{Sym,Len,T,N} <: AbstractArray{T,N}
> data::NTuple{Len,T}
> end
>
> julia> ndims(MyWeirdArray{:zero_offset, 15, Float64, 1})
> 1
>
> julia> eltype(MyWeirdArray{:zero_offset, 15, Float64, 1})
> Float64
>
> Both base/ julia and the ColorTypes package contain good examples of how
> to go
> about this kind of manipulation.
>
> Best,
> --Tim
>
> On Monday, February 15, 2016 05:28:19 AM Bart Janssens wrote:
> > There is the parameters field of the types, but I'm not sure if that's
> > considered private. You can do
> > Array{Float64, 1}.parameters[2]
> > to get 1, for example.
> >
> > On Monday, February 15, 2016 at 2:14:35 PM UTC+1, jw3126 wrote:
> > > I have an instance of a parametric type, is there a canonical way to
> get
> > > the parameter values?
> > > For example I could have some Array{T, d} and want to know whether T
> is
> > > Float64 and what its dimension is.
> > > The only way of doing this I am aware of is writing code like:
> > >
> > > dimension{T, dim}(arr::Array{T, dim}) = dim
> > > numbertype{T, dim}(arr::Array{T, dim}) = T
> > >
> > > Is there a built-in function to do this? And maybe a way to get
> parameter
> > > values for arbitrary types?
> > > E.g. I have some instance of MyType{S, T, U, n} is and want to know U.
> Do
> > > I have to repeat code like the above each time I define a new
> parametric
> > > type?
>
>
