In that case, you need traits. In fact the motivating example I gave in
my JuliaCon talk on this subject last year matches yours almost exactly:
https://youtu.be/j9w8oHfG1Ic
Anyway, probably you want to hand-code the Holy-traits. The example I
give in my talk modified to fit your example:
module M
export f, Trait1, Trait2
type Trait1 end
type Trait2 end
# this function does the grouping:
function traitfn end
# now define function f which should dispatch on those traits:
f(x) = _f(x, traitfn(x)) # wrapper
_f(x, ::Type{Trait1}) = x.a # logic for Trait1
_f(x, ::Type{Trait2}) = x.b+1 # logic for Trait2
end
using M
type T1 a::Float64 end
type T2 b::Float64 end
# now manually add your types to Trait1 or Trait2
M.traitfn(::T1) = Trait1
M.traitfn(::T2) = Trait2
t1 = T1(1.0)
t2 = T2(2.0)
println(f(t1))
println(f(t2))
Note, that the packages I mention in my talk are currently not
maintained but should work for Julia 0.4. But I may not have time to
udate them for 0.5.
On Mon, 2016-06-20 at 18:53, [email protected] wrote:
> Thanks to both of you for the replies.
>
> Module M contains a lot of functions for the simulation of dynamical models.
> Outside M, users are required to define some specific types to be consistent
> with another historical project. The definition of these types should be kept
> as simple as possible, this may look a bit odd, but forcing the user to define
> a type T1 <: AT1 is already too much, which is why Mauro's suggestion is not
> an
> option for me (but thanks anyway for the proposal!).
>
> And the tricky thing is that T1 and T2 can't be initialized before the module,
> so I can't do:
>
> type T1 a::Float64 end
> type T2 b::Float64 end
>
> module M
> import Main.T1, Main.T2
> function f(x::T1) return x.a end
> function f(x::T2) return x.b + 1 end
> export f
> end
>
> using M
> t1 = T1(1.0)
> t2 = T2(2.0)
> println(f(t1))
> println(f(t2))
>
> which works. If there is no solution similar to the first code I proposed, I
> think I'll simply use two different names such as f1(x::T1) and f2(x::T2) in
> M.
> But new suggestions are still highly appreciated :)
>
> Many thanks.
