Improved verbosity handling

[r4lv]

problem

For now, multiple output-related things exist in VIP:

• verbose parameter to functions
• debug parameter to functions
• timing information
• progress bars.

solution
I propose a new class, Logger, which takes care of these.

Internally, a Logger is defined by a numeric logging level (roughly following the logging levels of the standard library's logging module):

• ERROR = 40
• WARNING = 30
• INFO = 20
• DEBUG = 10

and one or multiple boolean tags:

• progressbar = True
• timing = True.

example

The new Logger class can be used as follows:

from xyz import Logger

@Logger.timing()
def andromeda(datacube=None, verbose=False):

	logger = Logger("andromeda", verbose)

	if datacube is None:
		logger.warn("The datacube is not set, that is maybe not what you want!")

	for i in Progressbar(range(1000), verbose=logger):
		logger.debug("loop #{}...".format(i))

	# ...

	logger.info("done.")

I can then call andromeda like so:

• andromeda(verbose=True) / andromeda(verbose="info")
  • These set level=20, progressbar=True, timing=True.
  • It will show the timing information, the progressbar, and the output of info and warn with the string "andromeda: " prefixed.
• if I want to disable the timing information, e.g. when I run andromeda inside a loop, I can add -timing to the verbose parameter: andromeda(verbose="info-timing") .
  • → level=20, progressbar=True, timing=False
• if I want to disable the output, I use andromeda(verbose=False) or andromeda(verbose='error').
  • It sets internally level=40, progressbar=False, timing=False.
• if I want just the progressbar, I can enable it separately using +progressbar: andromeda(verbose='error+progressbar')
  • → level=40, progressbar=True, timing=False

notes

The Progressbar class would check if the progressbar=True is set inside the Logger object it gets. The @Logger.timing() decorator does the same for the timing tag.

The Logger objects are entirely backwards-compatible to functions which expect a boolean as their verbose parameter, as they behave like a boolean when using e.g. if logger:. So there is no need to change anything existing.

I have the Logger class already coded, except for the @Logger.timing. I'll add that shortly, so we can try it out.

What do you think?