Re: I am close to using a behaviour as a pure interface and I feel dirty...

Erlang's behaviour is NOT an interface!
If you are looking for some analogy from other languages the closest one is
abstract classes in C#.



вт, 24 авг. 2021 г. в 01:00, Brett Hemes <[email protected]>:

> ... should I?
>
>
>
> I have some servers that carry around references to other (let’s call them
> child) servers.  Each of the referenced child servers are doing their own
> thing and are implemented as different modules but also share some common
> functions (albeit with different implementations).  At some point, I end up
> fetching a reference to a child server and want to make a call that is
> common to all of the child servers.  As of right now I do not know what
> specific type (module) the child server is, only that they ALL offer some
> subset of functionality.
>
>
>
> Assuming I am not approaching this entirely wrong (which could be the
> case) I have identified two leading options for my case:
>
>
>
> 1) use a behaviour (perhaps improperly) as a pure interface (i.e., with
> only callbacks and no "general" functionality).  For a child implemented in
> a `my_child_mod` module that implements behaviour `my_iface`, this could
> result in calls like `my_iface:a_common_fun(ChildServerRef)` after fetching
> the child server reference where I use the behaviour's module to access the
> child's functionality... OR
>
>
>
> 2) store the particular module of each child with the reference and use
> the stored module name at time of the call (and know/assume that all
> children have some shared functionality).  So using some tuple or similar
> `{my_child_mod, ChildServerRef}` (versus just the reference) could result
> in a call like `my_child_mod:a_common_fun(ChildServerRef)` after fetching
> the reference info (as a tuple).
>
>
>
> I, perhaps naively, gravitate towards #1 above for various reasons
> (compile-time checks, only having to carry around refs, my C++ background,
> etc.), but the internet (and ferd in particular here (
> https://stackoverflow.com/questions/4119477/implementing-interfaces-in-erlang/4119615#4119615))
> seems to imply that this is not the Erlang way (despite finding OTP cases
> like this:
> https://github.com/erlang/otp/blob/master/lib/ssh/src/ssh_sftpd_file_api.erl).
> ... shame on me?
>
>
>
>
>
> I am trying very hard to leave my C++ past behind and do things in the
> Erlang way, but need a little help in this particular case...
>
>
>
> Thanks,
>
> Brett
>