I’m working on a problem that requires that a vendor-specific module be loaded to handle vendor-specific tasks related to an order. I’ve been trying out the behaviours, and that all makes sense. Coming from an OO background, however, I’m feeling the need to have a factory in this case… where I wan…

FYI you could use the following to get module names from strings: my_module = "MyApp.VendorOne" module_atom = String.to_existing_atom("Elixir." <> my_module) module_atom == MyApp.VendorOne # true Edit: as indicated by others below (e.g. @sasajuric ’s), there are some better & safer approaches to th…

[image] fireproofsocks: Is this idiomatic? No. [image] fireproofsocks: Is there some other way to dynamically get a module name based on a parameter? Pass in the actual module name… def process_order(module), do: module.process() and you are ready to go.

What @NobbZ said, you could just call module.process() as then the function provides little extra value (I feel). Maybe call it vendor_module or something for more context :blush:

Relatedly, this fits in nicely if you can define a Behaviour https://elixir-lang.org/getting-started/typespecs-and-behaviours.html for the module that will do the processing.

Using behaviour + @impl MyBehaviour above the callbacks will give the compiler the ability to help you if you get incorrect arity, or add an extra callback to the behaviour that your module doesn’t yet implement, for example.

Honestly, I don’t like the Factory pattern. I prefer to be a bit more data centric. For example, each vendor has it’s own way to understand the orders, so you should have something like %VendorOneOrder{}, %VendorTwoOrder{}, etc… and they you apply the processing implementing a Protocol (Processable…

The responses here are far more interesting than I expected! Thanks! Re passing the module name – to clarify, you are not passing a string representing the module name, right? handle_processing(MyApp.VendorOne) # <--- can work with module.process() as desc'd above # But the following won't work …

Mind. Blown. I hadn’t even considered this approach (because I hadn’t really grok’d protocols until I thought about it in this light).

[image] imetallica: Honestly, I don’t like the Factory pattern. I prefer to be a bit more data centric. ALL of the “classic” (i.e. Gang of Four) patterns are specific to statically-typed languages, and virtually disappear with idiomatic use of dynamically-typed languages. [image] fireproo…

[image] sribe: ALL of the “classic” (i.e. Gang of Four) patterns are specific to statically-typed languages, and virtually disappear with idiomatic use of dynamically-typed languages. Functional Programming For The Rest of Us Introduction Programmers are procrastinators. Get in, …

[image] david_ex: module_atom = String.to_existing_atom("Elixir." <> my_module) This has some pitfalls. it will only work if the module name already exist! Either by preloading all modules or by having it already used in another already loaded module. It relies on the (documented) implement…

Factory Pattern in Elixir?

Questions & Help Questions

NobbZ February 12, 2019, 6:39am 2

No.

Pass in the actual module name… def process_order(module), do: module.process() and you are ready to go.