Hi Jon,
On Tue, Jan 12, 2016 at 8:53 AM, David P. Sanders <[email protected]>
wrote:
> El martes, 12 de enero de 2016, 10:36:50 (UTC-6), Jon Norberg escribió:
>>
>> I would like to create a composite type and then also create an array
>> that has values from this type by reference. The behaviour I am looking for
>> is like this:
>>
>> type c
>> a::Float64
>> b::Float64
>> end
>>
>> x=c(0.1,0.2)
>> y=c(0.3,0.4)
>>
>> z=[x.a,x.b,y.a,y.b]
>>
>> show(z)
>> [0.1,0.2,0.3,0.4]
>>
>> x.a=0.5
>>
>> show(z)
>> [0.5,0.2,0.3,0.4]
>>
>> z[4]=0.6
>>
>> show(y.b)
>> 0.6
>>
>> Is this possible?
>>
>
>
> You can get this effect by creating an array of the two objects (rather
> than of their components, which doesn't make much sense anyway):
>
> julia> type MyType
> a::Float64
> b::Float64
> end
>
> julia> x = MyType(1, 2)
> MyType(1.0,2.0)
>
> julia> y = MyType(3, 4)
> MyType(3.0,4.0)
>
> julia> z = [x, y]
> 2-element Array{MyType,1}:
> MyType(1.0,2.0)
> MyType(3.0,4.0)
>
> julia> x.a = 10
> 10.0
>
> julia> z
> 2-element Array{MyType,1}:
> MyType(10.0,2.0)
> MyType(3.0,4.0)
>
For the array itself, it is possible to view it in multiple ways using
immutable and reinterpret. But mimicking the answers above, it's not
possible to directly get a reference to the object (and even if it was, you
couldn't modify the individual parts of the object with that reference,
because here, it's immutable).
julia> immutable C
a::Float64
b::Float64
end
julia> z = [C(0.1,0.2), C(0.3,0.4)]
2-element Array{C,1}:
C(0.1,0.2)
C(0.3,0.4)
julia> z_view = reinterpret(Float64, z)
4-element Array{Float64,1}:
0.1
0.2
0.3
0.4
julia> z_view[4] = 0.6
0.6
julia> z
2-element Array{C,1}:
C(0.1,0.2)
C(0.3,0.6)
julia> z[1] = C(1.0, 2.0)
C(1.0,2.0)
julia> z_view
4-element Array{Float64,1}:
1.0
2.0
0.3
0.6
Cheers,
Kevin
