Change log file at runtime

[SadiinsoSnowfall]

Hi, Is it possible to change the log file(s) (specified using the chain(...) function on the logger builder) at runtime ? I have looked at the issue #76 (A way to change log level in runtime?) but I don't think that the proposed solution can be applied to this problem.

[daboross]

There isn't an easy solution to this built in at the moment.

I think this would be a reasonable feature to add to fern.

In the meantime, you could work around this by building a custom Log implementation which keeps track of the file via a global variable, and by passing that into chain with .chain(Box::new(GlobalFileLog) as Box<log::Log>).