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from abc import ABC |
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import attr |
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from typing import Tuple |
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from so_magic.utils import Subject, Command |
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from ..command_factory_interface import CommandFactoryInterface |
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class BaseCommandFactory(CommandFactoryInterface, ABC): |
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"""Facility that stores concrete implementations of CommandFactory.""" |
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subclasses = {} |
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@classmethod |
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def register_as_subclass(cls, factory_type): |
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def wrapper(subclass): |
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cls.subclasses[factory_type] = subclass |
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return subclass |
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return wrapper |
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@classmethod |
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def create(cls, factory_type, *args, **kwargs): |
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if factory_type not in cls.subclasses: |
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raise ValueError('Bad "Factory type" \'{}\''.format(factory_type)) |
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return cls.subclasses[factory_type](*args, **kwargs) |
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@BaseCommandFactory.register_as_subclass('generic') |
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class GenericCommandFactory(CommandFactoryInterface): |
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"""Command Factory that constructs a command given all the necessary arguments. |
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Assumes the 1st argument is the 'receiver' (see Command module), |
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2nd is the method to call on the receiver and the rest are the method's runtime arguments. |
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""" |
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def construct(self, *args, **kwargs) -> Command: |
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return Command(*args, **kwargs) |
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@BaseCommandFactory.register_as_subclass('function') |
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class FunctionCommandFactory(CommandFactoryInterface): |
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def construct(self, *args, **kwargs) -> Command: |
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if len(args) < 1: |
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raise RuntimeError("Will break") |
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return Command(args[0], '__call__', *args[1:]) |
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class CommandFactory: |
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"""A factory class able to construct new command objects.""" |
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constructors = {k: v().construct for k, v in BaseCommandFactory.subclasses.items()} |
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@classmethod |
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def pick(cls, *args, **kwargs): |
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decision = {True: 'function', False: 'generic'} |
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is_function = hasattr(args[0], '__code__') |
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dec2 = {'function': lambda x: x[0].__code__.co_name, 'generic': lambda x: type(x[0]).__name__ + '-' + x[1]} |
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return decision[is_function], kwargs.get('name', dec2[decision[is_function]](args)) |
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@classmethod |
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def create(cls, *args, **kwargs) -> Tuple[Command, str]: |
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key, name = cls.pick(*args, **kwargs) |
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if len(args) < 1: |
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raise RuntimeError(args) |
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return cls.constructors[key](*args), name |
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@attr.s |
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class MagicCommandFactory(Subject): |
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"""Instances of this class act as callable command factories that notify, |
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subscribed observers/listeners upon new command object creation. |
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Args: |
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command_factory (CommandFactory, optional): an instance of a CommandFActory |
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""" |
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command_factory = attr.ib(init=True, default=CommandFactory()) |
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def __call__(self, *args, **kwargs): |
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self._state, self.name = self.command_factory.create(*args, **kwargs) |
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self.notify() |
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return self._state |
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boromir674 /
so-magic
