What should we do if a backend requires open()

[hagenw]

In https://github.com/audeering/audbackend/pull/204 we introduced open() and close() methods.

At the moment, I'm cleaning up the authentication process for Artifactory and thought that it would make sense to move the authentication from __init__() to open(). The problem, I'm experiencing with this approach is that I don't know how I should handle the case if a user does not call open(), but tries to directly access some file, e.g. with exists(). Should I raise a audbackend.BackenError and state that the backend needs to be first opened?

[hagenw]

On the other hand with authentication there is nothing that needs to be closed, so maybe I just leave it within __init__()?

[frankenjoe]

To me open() seems the better fit.

The problem, I'm experiencing with this approach is that I don't know how I should handle the case if a user does not call open(), but tries to directly access some file, e.g. with exists()

To me the safest solution would be that we make calling open() mandatory. I remember you were arguing that it could be annoying for a user to do so. But I don't see this a big issue here since you only have to call it once in the beginning of your application and usually the call is anyway hidden inside a package like audb.

[hagenw]

When making it mandatory, couldn't we integrate it again in __init__()? Then you can still use it with with, or you call close() at the end.

[frankenjoe]

To me having a separate open function seems the cleaner solution. Though there are packages that offer only a close() function, e.g. soundfile. But sounddevice, on the other hand, comes with a start and stop function.

[frankenjoe]

One advantage of a separate open() function could be that you have a factory function that reads the host and repository from some configuration file and returns the backend object. While some other function then takes care of opening and closing the connection.

[hagenw]

Closed by #217