Split addon code up by purpose

subprocess_adapter.py

@@ -0,0 +1,50 @@
+import logging
+from multiprocessing import Process, Pipe
+
+class SubprocessOperatorMixin:
+    timer = None
+    log = logging.getLogger("%s.SubprocessOperatorMixin" % __name__)
+
+    # run once in invoke
+    def setup(self):
+        pass
+    # run on receipt of data from subprocess
+    def handle_response(self, resp):
+        pass
+
+    def __init__(self):
+        self.pipe = Pipe()
+        self.subprocess = None
+
+    def execute(self, context):
+        return self.invoke(context, None)
+
+    def invoke(self, context, event):
+        self.subprocess.start()
+        # we have to explicitly close the end of the pipe we are NOT using,
+        # otherwise no exception will be generated when the other process closes its end.
+        self.pipe[1].close()
+
+        wm = context.window_manager
+        wm.modal_handler_add(self)
+        self.timer = wm.event_timer_add(.01, context.window)
+
+        self.setup()
+
+        return {'RUNNING_MODAL'}
+
+    def modal(self, context, event):
+        self.log.debug("polling")
+        try:
+            if self.pipe[0].poll():
+                newdata = self.pipe[0].recv()
+            else:
+                newdata = None
+        except EOFError:
+            self.log.debug("done polling")
+            return {'FINISHED'}
+
+        if newdata is not None:
+            self.handle_response(newdata)
+        return {'PASS_THROUGH'}
+