slog: both AtomicLevel and Level implement Leveler

Introduce the Leveler interface (only method: Level() Level) so that
both AtomicLevel and Level can be used interchangeably.

HandlerOptions.Level is now a Leveler.

The default for HandlerOptions.Level is InfoLevel, meaning
that Debug logs are disabled by default.

This is also now the behavior of the default Handler, which
is used if slog.{Log,Info,Debug,...} are called before
installing a handler. It used to write everything to the
default log.Logger; now it ignores any level below Info.

Change-Id: I0538201cffacd101901179a01f262ae6a5d96797
Reviewed-on: https://go-review.googlesource.com/c/exp/+/431055
Run-TryBot: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
5 files changed
tree: da878d53fcf46327f4820b2204dd1fdc9e603adc
  1. apidiff/
  2. cmd/
  3. constraints/
  4. devtools/
  5. ebnf/
  6. ebnflint/
  7. errors/
  8. event/
  9. inotify/
  10. io/
  11. jsonrpc2/
  12. maps/
  13. mmap/
  14. rand/
  15. shiny/
  16. shootout/
  17. slices/
  18. slog/
  19. sumdb/
  20. typeparams/
  21. utf8string/
  22. .gitattributes
  23. .gitignore
  24. codereview.cfg
  25. CONTRIBUTING.md
  26. go.mod
  27. go.sum
  28. LICENSE
  29. PATENTS
  30. README.md
README.md

exp

PkgGoDev

This subrepository holds experimental and deprecated (in the old directory) packages.

The idea for this subrepository originated as the pkg/exp directory of the main repository, but its presence there made it unavailable to users of the binary downloads of the Go installation. The subrepository has therefore been created to make it possible to go get these packages.

Warning: Packages here are experimental and unreliable. Some may one day be promoted to the main repository or other subrepository, or they may be modified arbitrarily or even disappear altogether.

In short, code in this subrepository is not subject to the Go 1 compatibility promise. (No subrepo is, but the promise is even more likely to be violated by go.exp than the others.)

Caveat emptor.