"normal" types are by definition heap-allocated, and are always manipulated
them through pointers. What you want is immutables
<http://docs.julialang.org/en/release-0.4/manual/types/#immutable-composite-types>
immutable Stuff
a::Int
b::Int
end
# Also, for zeros to work,
function zero(x::Type{Stuff})
Stuff(0, 0)
end
On Tuesday, May 10, 2016 at 4:04:37 PM UTC-4, Boylan, Ross wrote:
>
> I'm puzzled that a type consisting only of 2 integers doesn't qualify as
> "bitstype". Further experiment shows that the array seems to be an array
> of references, I don't know how to implement zero, and generally that I'm a
> bit lost :) My goal is to get a densely packed array of data. I assume
> that will use less memory and generate faster code; if not, maybe I should
> change my goal.
>
> BTW, my real use has a type more heterogeneous than 2 Int's, so a solution
> that uses a 2D array doesn't really generalize appropriately for me.
>
> module TT
> import Base.zero
>
> type Stuff
> a::Int
> b::Int
> end
>
> function zero(x::Stuff)
> Stuff(0, 0)
> end
>
> end
>
> julia> v=Array(TT.Stuff, 3) #as before
> 3-element Array{TT.Stuff,1}:
> #undef
> #undef
> #undef
>
> julia> s=TT.Stuff(3, 5)
> TT.Stuff(3,5)
>
> julia> v=fill(s, 2)
> 2-element Array{TT.Stuff,1}:
> TT.Stuff(3,5)
> TT.Stuff(3,5)
>
> julia> s.a=900
> 900
>
> julia> v ###OOPS: every array element points to the same instance
> 2-element Array{TT.Stuff,1}:
> TT.Stuff(900,5)
> TT.Stuff(900,5)
>
> julia> zero(TT.Stuff) # This is probably what needs to work for zeros()
> to work
> ERROR: MethodError: `zero` has no method matching zero(::Type{TT.Stuff})
>
> !julia> zero(TT.Stuff(1, 1)) # this at least calls the right c'tor
> TT.Stuff(0,0)
>
>
> Ross
> ________________________________________
> From: julia...@googlegroups.com <javascript:> [julia...@googlegroups.com
> <javascript:>] on behalf of Lutfullah Tomak [tomak...@gmail.com
> <javascript:>]
> Sent: Tuesday, May 10, 2016 12:04 AM
> To: julia-users
> Subject: [julia-users] undefined reference error
>
> You need to initialize array entries if you don't have eltype as bitstype.
> Here, undefined reference means you had not initialize the entry. And, full
> type assignment works because it initializes the entry.
>
>
