also refactored core.meow into seperate files in hope that it'll help solve circular imports

core/base_handler.py

@@ -0,0 +1,46 @@
+
+"""
+This file contains the base MEOW handler defintion. This should be inherited 
+from for all handler instances.
+
+Author(s): David Marchant
+"""
+
+from typing import Any, Tuple, Dict
+
+from core.correctness.vars import get_drt_imp_msg, VALID_CHANNELS
+from core.correctness.validation import check_implementation
+
+
+class BaseHandler:
+    # A channel for sending messages to the runner. Note that this will be 
+    # overridden by a MeowRunner, if a handler instance is passed to it, and so
+    # does not need to be initialised within the handler itself.
+    to_runner: VALID_CHANNELS
+    # Directory where queued jobs are initially written to. Note that this 
+    # will be overridden by a MeowRunner, if a handler instance is passed to 
+    # it, and so does not need to be initialised within the handler itself.
+    job_queue_dir:str
+    def __init__(self)->None:
+        """BaseHandler Constructor. This will check that any class inheriting 
+        from it implements its validation functions."""
+        check_implementation(type(self).handle, BaseHandler)
+        check_implementation(type(self).valid_handle_criteria, BaseHandler)
+
+    def __new__(cls, *args, **kwargs):
+        """A check that this base class is not instantiated itself, only 
+        inherited from"""
+        if cls is BaseHandler:
+            msg = get_drt_imp_msg(BaseHandler)
+            raise TypeError(msg)
+        return object.__new__(cls)
+
+    def valid_handle_criteria(self, event:Dict[str,Any])->Tuple[bool,str]:
+        """Function to determine given an event defintion, if this handler can 
+        process it or not. Must be implemented by any child process."""
+        pass
+
+    def handle(self, event:Dict[str,Any])->None:
+        """Function to handle a given event. Must be implemented by any child 
+        process."""
+        pass