Fail-Safe error handling for AutoColor feature

[NodyHub]

Hi folks,

I am using hclog in a project and instantiate the logger with a custom io.Writer, which should be fine according to the struct:

go-hclog/logger.go

Line 246 in fb16e2d

Output io.Writer

If ColorOption is set to AutoColor, we get only a collored output, if Output from the previous line is a true io.File

go-hclog/logger.go

Lines 273 to 275 in fb16e2d

	// Color the output. On Windows, colored logs are only available for io.Writers that
	// are concretely instances of *os.File.
	Color ColorOption

But, if Output is not an io.File, hclog panics, instead of a fail-safe operation and omitting colouring.

go-hclog/colorize_unix.go

Line 20 in fb16e2d

fi := l.checkWriterIsFile()

go-hclog/intlogger.go

Lines 879 to 887 in fb16e2d

	// checks if the underlying io.Writer is a file, and
	// panics if not. For use by colorization.
	func (l *intLogger) checkWriterIsFile() *os.File {
	fi, ok := l.writer.w.(*os.File)
	if !ok {
	panic("Cannot enable coloring of non-file Writers")
	}
	return fi
	}

As a fail-safe option, we can always switch to ColorOff, instead of panic.

go-hclog/logger.go

Line 83 in fb16e2d

ColorOff ColorOption = iota

Or, might i miss something?

[evanphx]

Hi!

Looks like the unix version of the colorization code is too strict, at the very least. It should be allowing any writer, not just *os.Files.

That being said, I think your question is more about what AutoColor should do and if it should, if colorization is not available on the output, simply disable colorization. That seems like better logic than we have today.