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""" |
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This module contains decorators that facilitate the `jsons` functions in an |
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alternative fashion. |
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""" |
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import warnings |
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from inspect import signature, Parameter, isawaitable, iscoroutinefunction |
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from jsons import JsonSerializable, dump, load, loads, loadb, dumps, dumpb |
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def loaded(parameters=True, returnvalue=True, fork_inst=JsonSerializable, |
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loader=load, **kwargs): |
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""" |
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Return a decorator that can call `jsons.load` upon all parameters and the |
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return value of the decorated function. |
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**Example**: |
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>>> from datetime import datetime |
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>>> @loaded() |
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... def func(arg: datetime) -> datetime: |
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... # arg is now of type datetime. |
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... return '2018-10-04T21:57:00Z' # This will become a datetime. |
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>>> res = func('2018-10-04T21:57:00Z') |
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>>> type(res).__name__ |
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'datetime' |
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:param parameters: determines whether parameters should be taken into |
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account. |
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:param returnvalue: determines whether the return value should be taken |
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into account. |
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:param fork_inst: if given, it uses this fork of ``JsonSerializable``. |
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:param kwargs: any keyword arguments that should be passed on to |
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`jsons.load` |
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:param loader: the load function which must be one of (``load``, |
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``loads``, ``loadb``) |
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:return: a decorator that can be placed on a function. |
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""" |
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assert loader in (load, loads, loadb) |
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return _get_decorator(parameters, returnvalue, fork_inst, loader, kwargs) |
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def dumped(parameters=True, returnvalue=True, fork_inst=JsonSerializable, |
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dumper=dump, **kwargs): |
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""" |
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Return a decorator that can call `jsons.dump` upon all parameters and the |
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return value of the decorated function. |
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**Example**: |
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>>> from datetime import datetime |
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>>> @dumped() |
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... def func(arg): |
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... # arg is now of type str. |
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... return datetime.now() |
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>>> res = func(datetime.now()) |
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>>> type(res).__name__ |
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'str' |
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:param parameters: determines whether parameters should be taken into |
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account. |
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:param returnvalue: determines whether the return value should be taken |
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into account. |
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:param fork_inst: if given, it uses this fork of ``JsonSerializable``. |
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:param kwargs: any keyword arguments that should be passed on to |
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`jsons.dump` |
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:param dumper: the dump function which must be one of (``dump``, |
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``dumps``, ``dumpb``) |
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:return: a decorator that can be placed on a function. |
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""" |
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assert dumper in (dump, dumps, dumpb) |
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return _get_decorator(parameters, returnvalue, fork_inst, dumper, kwargs) |
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def _get_params_sig(args, func): |
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sig = signature(func) |
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params = sig.parameters |
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param_names = [param_name for param_name in params] |
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result = [(args[i], params[param_names[i]]) for i in range(len(args))] |
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return result |
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def _map_args(args, decorated, fork_inst, mapper, mapper_kwargs): |
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params_sig = _get_params_sig(args, decorated) |
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new_args = [] |
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for arg, sig in params_sig: |
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if sig.name in ('self', 'cls') and hasattr(arg, decorated.__name__): |
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# `decorated` is a method and arg is either `self` or `cls`. |
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new_arg = arg |
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else: |
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cls = sig.annotation if sig.annotation != Parameter.empty else None |
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new_arg = mapper(arg, cls=cls, fork_inst=fork_inst, |
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**mapper_kwargs) |
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new_args.append(new_arg) |
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return new_args |
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def _map_returnvalue(returnvalue, decorated, fork_inst, mapper, mapper_kwargs): |
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return_annotation = signature(decorated).return_annotation |
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cls = return_annotation if return_annotation != Parameter.empty else None |
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result = mapper(returnvalue, cls=cls, fork_inst=fork_inst, **mapper_kwargs) |
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return result |
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def _run_decorated(decorated, mapper, fork_inst, args, kwargs, mapper_kwargs): |
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new_args = args |
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if mapper: |
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new_args = _map_args(args, decorated, fork_inst, mapper, mapper_kwargs) |
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result = decorated(*new_args, **kwargs) |
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return result |
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def _get_decorator(parameters, returnvalue, fork_inst, mapper, mapper_kwargs): |
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def _decorator(decorated): |
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def _wrapper(*args, **kwargs): |
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result = _run_decorated(decorated, mapper if parameters else None, |
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fork_inst, args, kwargs, mapper_kwargs) |
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if returnvalue: |
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result = _map_returnvalue(result, decorated, fork_inst, mapper, |
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mapper_kwargs) |
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return result |
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async def _async_wrapper(*args, **kwargs): |
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result = _run_decorated(decorated, mapper if parameters else None, |
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fork_inst, args, kwargs, mapper_kwargs) |
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if isawaitable(result): |
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result = await result |
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if returnvalue: |
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result = _map_returnvalue(result, decorated, fork_inst, mapper, |
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mapper_kwargs) |
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return result |
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if isinstance(decorated, staticmethod): |
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warnings.warn('You cannot decorate a static- or classmethod. ' |
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'You can still obtain the desired behavior by ' |
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'decorating your method first and then place ' |
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'@staticmethod/@classmethod on top (switching the ' |
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'order).') |
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raise Exception('Cannot decorate a static- or classmethod.') |
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if isinstance(decorated, type): |
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raise Exception('Cannot decorate a class.') |
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return _async_wrapper if iscoroutinefunction(decorated) else _wrapper |
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return _decorator |
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ramonhagenaars /
jsons
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