clusterview/clusterview/exceptions.py

from PyQt5.QtWidgets import QErrorMessage

from .mode import Mode


class InvalidStateError(Exception):
    pass


class InvalidModeError(Exception):
    """
    An exception to specify an invalid mode has been provided.
    """

    def __init__(self, mode):
        """
        Initializes the InvalidMode exception with a
        mode.
        """

        if not isinstance(mode, Mode):
            raise ValueError("Mode argument to InvalidMode must be of " +
                             " type mode")

        # Mode cases for invalid mode
        if mode == Mode.OFF:
            super().__init__("You must select a mode before continuing.")


def handle_exceptions(func):
    """
    A decorator designed to make exceptions thrown
    from a function easier to handle.

    The result will be that all exceptions coming from
    the decorated function will be caught and displayed
    as a error message box.

    Usage:

    @handle_exceptions
    def my_qt_func():
        raises SomeException
    """
    def wrapped(self, *args, **kwargs):
        try:
            return func(self, *args, **kwargs)
        except Exception as e:
            error_dialog = QErrorMessage()
            error_dialog.showMessage(str(e))
            error_dialog.exec_()

    return wrapped