I want to create a “module general” which provides an abstract type (fruit), to be subtyped in another “module specific”. In the “module general”, I want to provide operations on fruit in general, but which hae to rely on methods specific for the concrete type.
module general
export fruit,weights
abstract type fruit end
function weight end
weights(fruits) = [weight(fruit) for fruit in fruits]
end
module specific
using general
export apple,lemon,weight
struct apple <: fruit
taste
end
weight(f::apple)=0.2
struct lemon <: fruit
taste
end
weight(f::lemon)=0.1
end
using general,specific
weights([apple(:delicious),lemon(:bitter)])
As must be expected, this does not work: in “module general” the weight methods are undefined. The example is simplistic, and provides no reason why I would like to keep things in separate modules, I must ask you to take this as a given.
Is there any way I can, together, with the definition of an abstract class in “module general” provide functions that rely on using methods specific to subtypes, to be defined in another module? Or is that not the Julian way?
