What are your thoughts on a package-level logger that is disabled by default?

[atc0005]

Overview

Continuation of the discussion from #4.

Speaking as someone without a lot of experience writing packages/libraries, it seems like it could free the package to more liberally log useful troubleshooting details, while not emitting it into the usual stdout/stderr streams by default.

I'm testing this functionality from a fork of this project and one of the items I'm emitting is the JSON that is being sent to Teams via the webhook URL. I'm finding that this is useful troubleshooting information as I develop client app changes. I understand that specific JSON logging use-case might not extend to all users of the library, so perhaps wrapping it in some further call might be necessary (were it to be included at all).

Example

// logger is a package logger that can be enabled from client code to allow
// logging output from this package when desired/needed for troubleshooting
var logger *log.Logger

func init() {

	// Disable logging output by default unless client code explicitly
	// requests it
	logger = log.New(os.Stderr, "[goteamsnotify] ", 0)
	logger.SetOutput(ioutil.Discard)

}

// EnableLogging enables logging output from this package. Output is muted by
// default unless explicitly requested (by calling this function).
func EnableLogging() {
	logger.SetFlags(log.Ldate | log.Ltime | log.Lshortfile)
	logger.SetOutput(os.Stderr)
}

[atc0005]

@dasrick once we work out #6, are you open to including this functionality?

This is an example of where I feel I did not overuse package-level logging*:

default:
    logger.Println("AddSection: No cases matched, all fields assumed to be at zero-value, skipping section")
    //continue
    // we probably need to return an error here so that client code can
    // handle the situation accordingly
    return fmt.Errorf("all fields found to be at zero-value, skipping section")
}

logger.Println("AddSection: section contains at least one non-zero value, adding section")

mc.Sections = append(mc.Sections, s)

* compared to the verbosity of messages logged elsewhere during the initial development of the extended types ...