I want to create a parametric type whose parameter is inferred from the
parameter of an argument. A toy example:
using Images
type TLPixel{T}
data::T
function TLPixel(img::Image{T})
new(img.data[1,1])
end
end
If I do this:
julia tlp = TLPixel{typeof(img.data[1,1])}(img)
you have to provide an outer constructor as well when you define an
inner one. This is a bit confusing, have a look at the manual search
the list. Here using your example using Arrays as I don't know Images:
type TLPixel{T}
data::T
function TLPixel(img::Array{T})
new(img[1])
When you create an inner constructor, it deletes all default constructors. So
you have to provide the default outer constructor:
TLPixel{T}(img:Image{T}) = TLPixel{T}(img)
Despite appearances, {T} on the left hand side is very different from {T} on
the right: on the left it's acting as a
