Optional logging

[nesrve]

Hey! I've been using swift-service-lifecycle for a few terminal based applications, mostly for my TUI libraries and apps on top of it, to cleanly handle shutdowns without having to manually deal with unix signals - been a life saver. However, in all of my applications, i've not wanted to use logging - or more like can't use logging due to the environment in which the application is rendered - the terminal. To construct a ServiceGroup you're currently forced to pass a logger as an argument, and that logger needs to be instantiated - potentially wasting up resources and adds boilerplate code - especially so when you set up a no-op. This brings me to ask, can we make logging optional - without an API breaking change? Or, even consider an API breaking change for the sake of more ergonomically usage outside of server based CLI apps - such as TUIs.

[t089]

If I remember correctly, a NOOP logger is cheaper than an optional logger.

[nesrve]

Could be i'm not sure, but you have more boilerplate with noop over just initializing logger. Another question could also be, if we do default to noop, could that potentially lure users to accidentally use a noop logger given the availability of the logger property. Best case scenario would be to make the logger property a Logger? but that's an API breaking change.

[FranzBusch]

You have two options here. Either you can create a logger and set the log level to .warning or higher. Then ServiceLifecycle won't do any logging or as @t089 said you can use a NoOpLogger which will also disable any logging. Both are totally fine for terminal based applications.

[nesrve]

Yep, i've been setting up a noop logger in my applications. However it's redundant code, boilerplate if you will. I have to keep that logger as a state and pass around it wherever i want to create service groups, which is just added code because the library requires a logger even when you don't want to do logging. I was hoping this could be solved within the library, instead of in the user code. Maybe, a new initializer that doesn't take a logger, and defaults to noop? Would such a PR be welcome?