Newbie questions coming from Python/C++

[paulmelis]

@stevengj

@paulmelis

So it would seem that you manually need to export every method you want to make available as public interface for the class?

Note also that in many cases a large fraction of the methods you want to make available are actually extensions of functions defined in Base (or other modules), in which case you don’t need to export them (the caller is already using Base ).

So, for example, if you define a new numeric type and define methods for Base.+ , Base.sqrt , Base.show , Base./ , etcetera, you don’t need to export these.

Well, I would say that that is a very “numeric computing oriented” position. I know that’s the focus of Julia, but I’m currently exploring it as an intermediate between Python and C++ (as high-level as the former, as fast as the latter) and I suspect others approach Julia that way as well. So I might potentially use it for all kinds of things, not necessarily numeric computing (e.g. text processing, web apps, visualization).

@stevengj

But yes, you need to explicitly export new generic functions foo (i.e., new function names , not just new methods of existing functions) that you define, unless you want callers to access them via MyModule.foo .

Again, this might be my different approach in using Julia, as I’m currently (as a first step) doing OO-style programming, where you have a set of structs each with their own specific methods of which only a subset needs to be accessible outside the module. The methods are usually not really applicable to other types of structs. Overcoming this with the MyModule.foo(obj, ...) style is a bit suboptimal, having a form that suggests an object-oriented method call (which is impossible in Julia, I know) but still having to pass the actual object as first parameter.

I can actually at this point foresee that I might draw the conclusion that Julia is not a good fit for when you really want to do OO-style programming, but with higher (potential) performance than Python while not wanting to use C++.

Edit: After reading Julia OOP example I’d say OO-style here doesn’t necessary mean using inheritance and such, but working with a set of interrelated objects each with their own methods and performing operations on those objects. I hardly use inheritance in practice.