Add LoggingHandler for handling a spinner indicating an ongoing calculation

esbo_etc/lib/SpinnerHandler.py

@@ -0,0 +1,84 @@
+import logging
+import halo
+
+
+class SpinnerHandler(logging.Handler):
+    """
+    A handler for the logging-package to allow a spinner indicate an ongoing calculation.
+
+    The spinner is started by a log-message with the extra-key 'spinning':
+    logger.info("running...", extra={"spinning": True})
+    logger.info("end", extra={"spinning": False})
+    """
+
+    def __init__(self, spinner: halo.Halo = halo.Halo(spinner="moon"), level: int = logging.NOTSET):
+        """
+        Initialize a new spinner handler
+
+        Parameters
+        ----------
+        spinner : Halo
+            The spinner to show.
+        level : int
+            The logging level of this handler.
+        """
+        # Initialize super class
+        super(SpinnerHandler, self).__init__(level)
+        # save spinner
+        self._spinner = spinner
+        # set variable of current spinning status to False
+        self._spinning = False
+
+    def filter(self, record):
+        """
+        Check if this handler should be applied on the given log record.
+
+        Parameters
+        ----------
+        record : LogRecord
+            The log record to be checked
+
+        Returns
+        -------
+        res : bool
+            True if this handler should be applied on the given log record, otherwise False.
+        """
+        if hasattr(record, 'spinning'):
+            return True
+        else:
+            return self._spinning
+
+    def emit(self, record):
+        """
+        Add a spinner to the given log record and emit the final record.
+
+        Parameters
+        ----------
+        record : LogRecord
+            The log record to be extended.
+
+        Returns
+        -------
+        record : LogRecord
+            The extended log record.
+        """
+        if hasattr(record, 'spinning'):
+            # extra-key 'spinning' is given in the log record
+            if getattr(record, "spinning") != self._spinning:
+                # spinner state has to be changed
+                if getattr(record, "spinning"):
+                    # start spinner
+                    self._spinning = True
+                    self._spinner.start(record.msg)
+                else:
+                    # stop spinner
+                    self._spinning = False
+                    self._spinner.stop()
+            elif getattr(record, "spinning"):
+                # Change spinner text
+                self._spinner.text = record.msg
+        if self._spinning:
+            # clear the spinner before emitting the record in order to avoid doubled messages
+            self._spinner.clear()
+            # record.msg = "\r\033[K" + record.msg
+            return record

esbo_etc/lib/__init__.py

@@ -1,2 +1,3 @@
 from .helpers import *
 from .output import *
+from .SpinnerHandler import *