[julia-users] Incomplete parametric types

[Christopher Alexander]

Hi all,

Is there anyway to do something like the following?

abstract ABC

type A <: ABC end

type B <: ABC end

type TestType{T <:ABC}
        a::Float64
        b::T
        
        TestType(a::Float64) = new(a)
end

myT = TestType(4.0)
myT.b = A()

I am wondering if you can incompletely initialize a parametric type, and 
then set the actual value needed later.  The above code doesn't work, but 
that is what I'm trying to do.  The alternative is I guess to have some 
default Null Type, but then to get the performance gains I have to copy the 
object when I want to actually set it with the value that I want.

Thanks!

Chris