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"""This module is responsible to provide a formal way of registering phi functions |
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at runtime. See the 'PhiFunctionRegistrator' class and its 'register' decorator method |
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""" |
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import logging |
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import inspect |
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from typing import Callable |
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from so_magic.utils import Subject |
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logger = logging.getLogger(__name__) |
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class PhiFunctionMetaclass(type): |
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"""Class type with a single broadcasting (notifies listeners) facility. |
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Classes using this class as metaclass, obtain a single broadcasting facility |
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as a class attribute. The class attribute is called 'subject' can be referenced |
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as any class attribute. |
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Example: |
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class MyExampleClass(metaclass=PhiFunctionMetaclass): |
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pass |
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instance_object_1 = MyExampleClass() |
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instance_object_2 = MyExampleClass() |
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assert id(MyExampleClass.subject) == id(instance_object_1.subject) == id(instance_object_2.subject) |
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""" |
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def __new__(mcs, *args, **kwargs): |
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"""Create a new class type object and set the 'subject' attribute to a new Subject instance; the broadcaster. |
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Returns: |
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PhiFunctionMetaclass: the new class type object |
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""" |
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phi_function_class = super().__new__(mcs, *args, **kwargs) |
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phi_function_class.subject = Subject([]) |
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return phi_function_class |
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class PhiFunctionRegistrator(metaclass=PhiFunctionMetaclass): |
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"""Add phi functions to the registry and notify observers/listeners. |
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This class provides the 'register' decorator, that client can use to decorate either functions (defined with the |
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def python special word), or classes (defined with the python class special word). |
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""" |
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# NICE TO HAVE: make the decorator work without parenthesis |
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@classmethod |
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def register(cls, phi_name=''): |
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r"""Add a new phi function to phi function registry and notify listeners/observers. |
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Use this decorator around either a callable function (defined with the 'def' python special word) or a class |
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with a takes-no-arguments (or all-optional-arguments) constructor and a __call__ magic method. |
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All phi functions are expected to be registered with a __name__ and a __doc__ attribute. |
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You can select your custom phi_name under which to register the phi function or default to an automatic |
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determination of the phi_name to use. |
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Automatic determination of phi_name is done by examining either the __name__ attribute of the function or the |
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class name of the class. |
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Example: |
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>>> from so_magic.data.features.phi import PhiFunctionRegistrator |
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>>> from so_magic.utils import Observer, ObjectRegistry |
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>>> class PhiFunctionRegistry(Observer): |
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... def __init__(self): |
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... self.registry = ObjectRegistry() |
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... def update(self, subject, *args, **kwargs): |
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... self.registry.add(subject.name, subject.state) |
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>>> phis = PhiFunctionRegistry() |
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>>> PhiFunctionRegistrator.subject.add(phis) |
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>>> @PhiFunctionRegistrator.register() |
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... def f1(x): |
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... '''Multiply by 2.''' |
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... return x * 2 |
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Registering input function f1 as phi function, at key f1. |
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>>> phis.registry.get('f1').__doc__ |
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'Multiply by 2.' |
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>>> input_value = 5 |
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>>> print(f"{input_value} * 2 = {phis.registry.get('f1')(input_value)}") |
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5 * 2 = 10 |
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>>> @PhiFunctionRegistrator.register() |
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... class f2: |
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... def __call__(self, data, **kwargs): |
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... return data + 5 |
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Registering input class f2 instance as phi function, at key f2. |
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>>> input_value = 1 |
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>>> print(f"{input_value} + 5 = {phis.registry.get('f2')(input_value)}") |
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1 + 5 = 6 |
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>>> @PhiFunctionRegistrator.register('f3') |
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... class MyCustomClass: |
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... def __call__(self, data, **kwargs): |
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... return data + 1 |
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Registering input class MyCustomClass instance as phi function, at key f3. |
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>>> input_value = 3 |
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>>> print(f"{input_value} + 1 = {phis.registry.get('f3')(input_value)}") |
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3 + 1 = 4 |
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Args: |
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phi_name (str, optional): custom name to register the phi function. Defaults to automatic computation. |
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""" |
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def wrapper(a_callable): |
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"""Add a callable object to the phi function registry and preserve info for __name__ and __doc__ attributes. |
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The callable object should either be function (defined with def) or a class (defined with class). In case of |
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a class the class must have a constructor that takes no arguments (or all arguments are optional) and a |
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__call__ magic method. |
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Registers the callable as a phi function under the given or automatically computed name, makes sure the |
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__name__ and __doc__ attributes preserve information and notifies potential listeners/observers. |
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Args: |
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a_callable (Callable): the object (function or class) to register as phi function |
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""" |
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if hasattr(a_callable, '__code__'): # it is a function (def func_name ..) |
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logging.info("Registering input function %s as phi function.", a_callable.__code__.co_name) |
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key = phi_name if phi_name else cls.get_name(a_callable) |
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print(f"Registering input function {a_callable.__code__.co_name} as phi function, at key {key}.") |
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cls._register(a_callable, key) |
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else: |
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if not hasattr(a_callable, '__call__'): |
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raise RuntimeError("Expected an class definition with a '__call__' instance method defined 1." |
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f" Got {type(a_callable)}") |
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members = inspect.getmembers(a_callable) |
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if ('__call__', a_callable.__call__) not in members: |
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raise RuntimeError("Expected an class definition with a '__call__' instance method defined 2." |
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f" Got {type(a_callable)}") |
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instance = a_callable() |
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instance.__name__ = a_callable.__name__ |
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instance.__doc__ = a_callable.__call__.__doc__ |
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key = phi_name if phi_name else cls.get_name(instance) |
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print(f"Registering input class {a_callable.__name__} instance as phi function, at key {key}.") |
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cls._register(instance, key) |
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return a_callable |
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return wrapper |
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@classmethod |
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def _register(cls, a_callable, key_name): |
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"""Register a callable as phi function and notify potential listeners/observers. |
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The phi function is registered under the given key_name or in case of None the name is automatically computed |
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based on the input callable. |
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Args: |
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a_callable (Callable): the callable that holds the business logic of the phi function |
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key_name (str, optional): custom phi name. Defaults to None, which means automatic determination of the name |
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""" |
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cls.subject.name = key_name |
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cls.subject.state = a_callable |
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cls.subject.notify() |
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@staticmethod |
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def get_name(a_callable: Callable): |
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"""Get the 'name' of the input callable object |
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Args: |
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a_callable (Callable): a callable object to get its name |
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Returns: |
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str: the name of the callable object |
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""" |
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if hasattr(a_callable, 'name'): |
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return a_callable.name |
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if hasattr(a_callable, '__code__') and hasattr(a_callable.__code__, 'co_name'): |
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return a_callable.__code__.co_name |
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if hasattr(type(a_callable), 'name'): |
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return type(a_callable).name |
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if hasattr(type(a_callable), '__name__'): |
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return type(a_callable).__name__ |
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raise PhiFunctionNameDeterminationError() |
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class PhiFunctionNameDeterminationError(Exception): pass |
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