I had not intended to take a month off, but then GopherCon came, and life happened… but now I’m back, and ready to rock and roll again…

Today we’re to the core of the Handler interface: the Handle method.

type Handler

type Handler interface {
  …

	// Handle handles the Record.
	// It will only be called when Enabled returns true.
	// The Context argument is as for Enabled.
	// It is present solely to provide Handlers access to the context's values.
	// Canceling the context should not affect record processing.
	// (Among other things, log messages may be necessary to debug a
	// cancellation-related problem.)
	//
	// Handle methods that produce output should observe the following rules:
	//   - If r.Time is the zero time, ignore the time.
	//   - If r.PC is zero, ignore it.
	//   - Attr's values should be resolved.
	//   - If an Attr's key and value are both the zero value, ignore the Attr.
	//     This can be tested with attr.Equal(Attr{}).
	//   - If a group's key is empty, inline the group's Attrs.
	//   - If a group has no Attrs (even if it has a non-empty key),
	//     ignore it.
	//
	// [Logger] discards any errors from Handle. Wrap the Handle method to
	// process any errors from Handlers.
	Handle(context.Context, Record) error

When implementing a handler, the docs above explain two general rules that must be followed:

- Don't log if the record's level is lower than the handler's configured level.
- Ignore certain zero values.

but what I find most interesting is that `Handle` returns an eror that is explicitly ignored.  I don't know the reason this choice was made. It strikes me as an unusual departure from convention. And the sugested work-around I find also to be odd:  Wrap the `Handle` method to handle any errors.  This puts the responsibility for error handling in an awkward spot—neither the `Handler` author, nor the `logger` consumer are directly responsible. Rather, a `Handler` needs to be wrapped with custom error-handling code.

My personal advice: If you're writing a log handler, don't return errors from `Handle`. 😊 If you do return an error there, I'd be careful to document that clearly in your package's documention.