feat: Add context manager for modio instance

Signed-off-by: Sven Sager <akira@narux.de>

src/revpimodio2/io.py

@@ -99,9 +99,11 @@ class IOList(object):
         When 'autorefresh=True' is used, all read or write actions in the
         background are performed automatically.
         """
-        if self.__modio._looprunning:
-            raise RuntimeError("can not start multiple mainloop/cycleloop/with sessions")
-        self.__modio._looprunning = True
+        if not self.__modio._context_manager:
+            # If ModIO itself is in a context manager, it sets the _looprunning=True flag itself
+            if self.__modio._looprunning:
+                raise RuntimeError("can not enter context manager inside mainloop or cycleloop")
+            self.__modio._looprunning = True
 
         self.__modio.readprocimg()
         return self
@@ -114,7 +116,9 @@ class IOList(object):
         outputs are automatically written in the background.
         """
         self.__modio.writeprocimg()
-        self.__modio._looprunning = False
+        if self.__modio._context_manager:
+            # Do not reset if ModIO is in a context manager itself, it will handle that flag
+            self.__modio._looprunning = False
 
     def __getattr__(self, key):
         """

src/revpimodio2/modio.py

@@ -70,6 +70,7 @@ class RevPiModIO(object):
         "_autorefresh",
         "_buffedwrite",
         "_configrsc",
+        "_context_manager",
         "_debug",
         "_devselect",
         "_exit",
@@ -146,6 +147,7 @@ class RevPiModIO(object):
 
         self._autorefresh = autorefresh
         self._configrsc = configrsc
+        self._context_manager = False
         self._monitoring = monitoring
         self._procimg = "/dev/piControl0" if procimg is None else procimg
         self._set_device_based_cycle_time = True
@@ -205,6 +207,22 @@ class RevPiModIO(object):
             if self._myfh is not None:
                 self._myfh.close()
 
+    def __enter__(self):
+        if self._context_manager:
+            raise RuntimeError("can not use multiple context managers of same instance")
+        if self._looprunning:
+            raise RuntimeError("can not enter context manager with running mainloop or cycleloop")
+        self._context_manager = True
+        self._looprunning = True
+
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.writeprocimg()
+        self.exit(full=True)
+        self._looprunning = False
+        self._context_manager = False
+
     def __evt_exit(self, signum, sigframe) -> None:
         """
         Eventhandler fuer Programmende.
@@ -805,6 +823,9 @@ class RevPiModIO(object):
         :param blocking: Wenn False, blockiert das Programm hier NICHT
         :return: None or the return value of the cycle function
         """
+        # Check for context manager
+        if self._context_manager:
+            raise RuntimeError("Can not start cycleloop inside a context manager (with statement)")
         # Prüfen ob ein Loop bereits läuft
         if self._looprunning:
             raise RuntimeError("can not start multiple loops mainloop/cycleloop")
@@ -1060,6 +1081,9 @@ class RevPiModIO(object):
 
         :param blocking: Wenn False, blockiert das Programm hier NICHT
         """
+        # Check for context manager
+        if self._context_manager:
+            raise RuntimeError("Can not start mainloop inside a context manager (with statement)")
         # Prüfen ob ein Loop bereits läuft
         if self._looprunning:
             raise RuntimeError("can not start multiple loops mainloop/cycleloop")