Ok, thanks, we are getting closer to what I need, but still...
julia> a=1
1
julia> b=Ref(a)
Base.RefValue{Int64}(1)
julia> b[]+=3
4
julia> a
1
while I was expecting a==4
Il giorno sab 3 ott 2015 alle ore 19:16 Yichao Yu <[email protected]> ha
scritto:
> On Sat, Oct 3, 2015 at 12:48 PM, Carlo Lucibello
> <[email protected]> wrote:
> > Those don't seem to be viable solutions. In fact
> >
> > julia> a=2
> > 2
> >
> > julia> b=Ref(a)
> > Base.RefValue{Int64}(2)
> >
> > julia> b += 3
> > ERROR: MethodError: `+` has no method matching +(::Base.RefValue{Int64},
> > ::Int64)
>
> b[] += 3
>
> >
> > and also how do you define a 0-dimensional array?
> >
> > a=Array{Float64,0}()
> > ERROR: MethodError: `convert` has no method matching
> > convert(::Type{Array{Float64,0}})
> > This may have arisen from a call to the constructor
> Array{Float64,0}(...),
> > since type constructors fall back to convert methods.
> >
> >
> >
> > Il giorno sabato 3 ottobre 2015 18:07:51 UTC+2, Jameson ha scritto:
> >>
> >> the `Ref` type or the single-valued `Array{T,0}` provides this ability
> for
> >> Julia.
> >>
> >> On Fri, Oct 2, 2015 at 5:10 PM Carlo Lucibello <[email protected]>
> >> wrote:
> >>>
> >>> Hi julians,
> >>> I'd like to emulate the following behaviour from C++
> >>>
> >>> class A{
> >>> public:
> >>> double x;
> >>> }
> >>>
> >>> class B{
> >>> public:
> >>> double& x;
> >>> }
> >>> A a(1);
> >>> B b(a.x);
> >>> a.x=2;
> >>> assert(b.x == 2);
> >>>
> >>> Whilie it would be easy to obtain this behaviour with `composite`
> types,
> >>> since they are passed by referece, for elementary types, such as
> Float64,
> >>> thi is not possible since they have a sort of by vlue semantic (yes, I
> know
> >>> it's not exactly like that, but still...)
> >>>
> >>> Greetings,
> >>> Carlo
>
