62 lines
2.5 KiB
Python
62 lines
2.5 KiB
Python
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"""
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This file contains the base MEOW handler defintion. This should be inherited
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from for all handler instances.
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Author(s): David Marchant
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"""
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from typing import Any, Tuple, Dict
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from meow_base.core.correctness.vars import VALID_CHANNELS, \
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VALID_HANDLER_NAME_CHARS, get_drt_imp_msg
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from meow_base.core.correctness.validation import check_implementation, \
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valid_string
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from meow_base.functionality.naming import generate_handler_id
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class BaseHandler:
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# An identifier for a handler within the runner. Can be manually set in
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# the constructor, or autogenerated if no name provided.
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name:str
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# A channel for sending messages to the runner. Note that this will be
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# overridden by a MeowRunner, if a handler instance is passed to it, and so
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# does not need to be initialised within the handler itself.
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to_runner: VALID_CHANNELS
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# Directory where queued jobs are initially written to. Note that this
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# will be overridden by a MeowRunner, if a handler instance is passed to
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# it, and so does not need to be initialised within the handler itself.
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job_queue_dir:str
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def __init__(self, name:str='')->None:
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"""BaseHandler Constructor. This will check that any class inheriting
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from it implements its validation functions."""
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check_implementation(type(self).handle, BaseHandler)
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check_implementation(type(self).valid_handle_criteria, BaseHandler)
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if not name:
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name = generate_handler_id()
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self._is_valid_name(name)
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self.name = name
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def __new__(cls, *args, **kwargs):
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"""A check that this base class is not instantiated itself, only
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inherited from"""
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if cls is BaseHandler:
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msg = get_drt_imp_msg(BaseHandler)
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raise TypeError(msg)
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return object.__new__(cls)
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def _is_valid_name(self, name:str)->None:
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"""Validation check for 'name' variable from main constructor. Is
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automatically called during initialisation. This does not need to be
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overridden by child classes."""
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valid_string(name, VALID_HANDLER_NAME_CHARS)
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def valid_handle_criteria(self, event:Dict[str,Any])->Tuple[bool,str]:
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"""Function to determine given an event defintion, if this handler can
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process it or not. Must be implemented by any child process."""
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pass
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def handle(self, event:Dict[str,Any])->None:
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"""Function to handle a given event. Must be implemented by any child
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process."""
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pass
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