legion Python module contains miscellaneous functions and constants for the maintenance scripts of my private system. It is shared in this public repository just in case its code may be of help for other programmers.

The current API (symbols and functions) follows.

• Module constants:

  • DESKTOP_PATH
    Path of user's Desktop directory.
  • PROGRAM_PATH
    Path of the currently executing script.
  • PROGRAM_NAME
    User friendly name of the currently executing script.
  • DEFAULT_CREDENTIALS_FILE
    Filename used by default by get_credentials() for user credentials.
  • TIMESTAMP_FORMAT
time.strftime() compatible format specification for timestamps.
  • ARROW_L
    Left pointing arrow character for pretty-printing program output.
  • ARROW_R
    Right pointing arrow character for pretty-printing program output.
  • ERROR_MARKER
    Marker string prepended to error messages.
  • UTF8
    Normalized name for UTF-8 encoding.

• WFKStatuses
  Available for win32platform, only, they are the possible return values for wait_for_keypress(), implemented for now as an IntEnum:

  • WFKStatuses.NO_WIN32
    Do not wait for keypress, no win32 platform.
  • WFKStatuses.NO_CONSOLE_ATTACHED
    Do not wait for keypress, no console attached.
  • WFKStatuses.NO_CONSOLE_TITLE
    Do not wait for keypress, no console title.
  • WFKStatuses.NO_TRANSIENT_FROZEN
    Do not wait for keypress, no transient console with frozen executable.
  • WFKStatuses.NO_TRANSIENT_PYTHON
    Do not wait for keypress, no transient console with Python script.
  • WFKStatuses.WAIT_FOR_KEYPRESS
    Wait for keypress.

• logger
  Default per-application logger instance. Its public interface is identical to logging.Logger objects but it also includes indentation support and a simple configuration system by adding the following methods:

  • set_indent(level: int) -> None
    Set the logger indentation level to level. Negative values are ignored and zero is used instead.
  • indent() -> None Increment current logger indentation level.
  • dedent() -> None Decrement current logger indentation level.
  • config(
debugfile: str|Path|None = None,
logfile: str|Path|None = None,
console: bool = True
) -> None
    Configure logger.

  With the default configuration ALL logging messages are sent to debugfile with a timestamp and some debugging information; those messages with severity of logging.INFO or higher are sent to logfile, also timestamped.

  In addition to that, and if console is True (the default), messages with a severity of logging.INFO (and only those) are sent to the standard output stream, and messages with a severity of logging.WARNING or higher are sent to the standard error stream, without a timestamp in both cases.

  If debugfile or logfile are None (the default), then the corresponding files are not created and no logging message will go there. In this case, if console is False, NO LOGGING OUTPUT WILL BE PRODUCED AT ALL.

• error(
message: str,
details: str = ''
) -> None
  Preprocess and log error message, optionally including details.

  A header/marker is prepended to the message, and a visual separator is prepended to the details. Both the message and the details are indented.

  Finally, everything is logged using logging.error().

• excepthook(
exc_type: type[BaseException],
exc_value: BaseException,
exc_traceback: TracebackType | None
) -> None
  Log information about unhandled exceptions using the provided exception type, value and associated traceback.

  For KeyboardInterrupt exceptions, no logging is performed, the default exception hook is used instead.

  For OSError exceptions, a different message is logged, including particular OSError information, and no traceback is logged.

  For any other unhandled exception, a generic message is logged together with the traceback, if available.

  Finally, depending on the platform, some kind of modal dialog is shown so the end user does not miss the error.

  Intended to be used as default exception hook (sys.excepthook).

• munge_oserror(
exception: OSError
) -> tuple[str, str, str, str, str]
  Process the exception object for OSError exceptions (and its subclasses), and return a tuple containing the processed information.

  First item is the actual OSError subclass which was raised, as a string.

  Second item is the errno and winerror codes, separated by a slash if both are present. If no error codes exist in the exception object, this item is replaced by an informative placeholder.

  The third item is the error message, starting with an uppercase letter and ending in a period. If it does not exist, it will be an empty string.

  Final two items are the filenames involved in the exception. Depending on the actual exception, there may be zero, one or two filenames involved. If some of the filenames is not present in the exception object, it will still be in the tuple but it's value will be None.

• prettyprint_oserror(
reason: str,
exc: OSError
) -> None
  Print a very simple OSError message using the reason and exception information.

• timestamp() -> str
  Produce a timestamp string from current local date and time.

• run(
command: Sequence[str],
**subprocess_args: Any
) -> subprocess.CompletedProcess[str]
  Run command, using subprocess_args as arguments. This is just a helper for subprocess.run() to make such calls more convenient by providing a set of defaults for the arguments.

  For that reason, the keyword arguments accepted in subprocess_args and the return value for this function are the exact same ones accepted and returned by the subprocess.run() function itself.

• Deprecated setup_logging(debugfile=None, logfile=None, console=True)
  Set up logging system, disabling all existing loggers.

  With the current configuration ALL logging messages are sent to debugfile and logging.INFO messages are sent to logfile, timestamped.

  In addition to that, and if console is True (the default), all logging.INFO messages are sent to the console too, but without a timestamp.

  If debugfile or logfile are None, the corresponding files are not created and no logging message will go there. In this case, if console is False, NO LOGGING OUTPUT WILL BE PRODUCED AT ALL.

• Deprecated logging.indent(level=None)
  If level is provided, set the current logging indentation level to that number, meaning that logging messages will be prepended with that many copies of the current logging indentation character.

  If level is not provided or is None, the current logging indentation level is increased in 1 copy of the current logging indentation character.

• Deprecated logging.dedent(level=None)
  If level is provided, set the current logging indentation level to that number, meaning that logging messages will be prepended with that many copies of the current logging indentation character.

  If level is not provided or is None, the current logging indentation level is decreased in 1 copy of the current logging indentation character.

• wait_for_keypress() -> WFKStatuses
  Wait for a keypress to continue if sys.stdout is a real console AND the console is transient.

  For win32 platform only.

• get_credentials(
credentials_path: Path = _Config.CREDENTIALS_FILE
) -> dict[str, Any] | None
  Get credentials for current user, from the file at credentials_path.

  If credentials_path if not provided as argument, a default path is used.

  No matter the actual syntax of the file, which may change in the future, the credentials are returned as a simple two-levels dictionary. The first level are the different sections, intended to group credentials. The second level are the credentials themselves. They are accessed by credential identifier and returned as strings.

  If credentials file cannot be read or has syntax problems, None is returned.

• Both sys.stdout and sys.stderr are automatically reconfigured into UTF-8 mode.
• Very basic logging configuration is performed even when logger.setup() is not called: all logging messages will be handled and sent to console with a default format (currently, just the logging message, without any context), and all default logging handlers are removed from the root logger after closing them. No indentation of logging messages is possible.
• A new logging class is set up by the logger, with indentation support, so ALL new loggers created by the application importing this module will have that new class (not exposed on purpose). This can be changed at any time by the application by calling logging.setLoggerClass() with the desired class.
• The provided exception hook is registered at sys.excepthook. The previously registered one is still accessible at sys.__excepthook__ if needed.
• Under win32, an atexit handler is registered which waits for a keypress when the program exits if it is running on a transient console.
• If the module is run rather than imported, it prints some demos. Currently, a timestamp and the names and values of all constants which are valid in all platforms.