kython.klogging

- move to core
- add a proper description why it's useful
- make default level INFO
- use HPI_LOGS variable for easier log level control (abdc6df1ea)

my/core/logging.py

@@ -0,0 +1,91 @@
+#!/usr/bin/env python3
+'''
+Default logger is a bit, see 'test'/run this file for a demo
+'''
+
+def test() -> None:
+    import logging
+    import sys
+    M = lambda s: print(s, file=sys.stderr)
+
+    M("   Logging module's deafults are not great...'")
+    l = logging.getLogger('test_logger')
+    l.error("For example, this should be logged as error. But it's not even formatted properly, doesn't have logger name or level")
+
+    M("   The reason is that you need to remember to call basicConfig() first")
+    logging.basicConfig()
+    l.error("OK, this is better. But the default format kinda sucks, I prefer having timestamps and the file/line number")
+
+    M("")
+    M("    With LazyLogger you get a reasonable logging format, colours and other neat things")
+
+    ll = LazyLogger('test') # No need for basicConfig!
+    ll.info("default level is INFO")
+    ll.debug(".. so this shouldn't be displayed")
+    ll.warning("warnings are easy to spot!")
+    ll.exception(RuntimeError("exceptions as well"))
+
+
+import logging
+from typing import Union, Optional
+import os
+
+Level = int
+LevelIsh = Optional[Union[Level, str]]
+
+
+def mklevel(level: LevelIsh) -> Level:
+    glevel = os.environ.get('HPI_LOGS', None)
+    if glevel is not None:
+        level = glevel
+    if level is None:
+        return logging.NOTSET
+    if isinstance(level, int):
+        return level
+    return getattr(logging, level.upper())
+
+
+FORMAT = '{start}[%(levelname)-7s %(asctime)s %(name)s %(filename)s:%(lineno)d]{end} %(message)s'
+FORMAT_COLOR   = FORMAT.format(start='%(color)s', end='%(end_color)s')
+FORMAT_NOCOLOR = FORMAT.format(start='', end='')
+DATEFMT = '%Y-%m-%d %H:%M:%S'
+
+
+def setup_logger(logger: logging.Logger, level: LevelIsh) -> None:
+    lvl = mklevel(level)
+    try:
+        import logzero # type: ignore[import]
+    except ModuleNotFoundError:
+        import warnings
+        warnings.warn("You might want to install 'logzero' for nice colored logs!")
+        logger.setLevel(lvl)
+        h = logging.StreamHandler()
+        h.setLevel(lvl)
+        h.setFormatter(logging.Formatter(fmt=FORMAT_NOCOLOR, datefmt=DATEFMT))
+        logger.addHandler(h)
+        logger.propagate = False # ugh. otherwise it duplicates log messages? not sure about it..
+    else:
+        formatter = logzero.LogFormatter(
+            fmt=FORMAT_COLOR,
+            datefmt=DATEFMT,
+        )
+        logzero.setup_logger(logger.name, level=lvl, formatter=formatter)
+
+
+class LazyLogger(logging.Logger):
+    def __new__(cls, name, level: LevelIsh = 'INFO'):
+        logger = logging.getLogger(name)
+        # this is called prior to all _log calls so makes sense to do it here?
+        def isEnabledFor_lazyinit(*args, logger=logger, orig=logger.isEnabledFor, **kwargs):
+            att = 'lazylogger_init_done'
+            if not getattr(logger, att, False): # init once, if necessary
+                setup_logger(logger, level=level)
+                setattr(logger, att, True)
+            return orig(*args, **kwargs)
+
+        logger.isEnabledFor = isEnabledFor_lazyinit  # type: ignore[assignment]
+        return logger
+
+
+if __name__ == '__main__':
+    test()