Allow forking from existing loggers

[SpriteOvO]

Closes #13.

To avoid confusion with the semantics of Arc::clone, I have named the new methods as fork_xxx.

Unsolved Questions

• [x] Not sure if fn fork(self: &Arc<Self>) -> Result<Arc<Self>> (no modifier, just fork as is) is also necessary to add.

  • We chose not to implement it because we couldn't imagine a use case that needed it. (https://github.com/SpriteOvO/spdlog-rs/pull/15#issuecomment-1276089006)

[Lancern]

Not sure if fn fork(self: &Arc<Self>) -> Result<Arc<Self>> (no modifier, just fork as is) is also necessary to add.

I can't imagine a use case for this function. Is it necessary? What's the use case?

[SpriteOvO]

Not sure if fn fork(self: &Arc<Self>) -> Result<Arc<Self>> (no modifier, just fork as is) is also necessary to add.

I can't imagine a use case for this function. Is it necessary? What's the use case?

I can't either. So let's not implement it and wait for a feature request to be opened by someone who needs it.