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import inspect
from collections import OrderedDict
from typing import Callable, Any, Union, Iterable, Dict, Tuple
from typish._types import Empty
from typish.classes._cls_dict import ClsDict
class ClsFunction:
"""
ClsDict is a callable that takes a ClsDict or a dict. When called, it uses
the first argument to check for the right function in its body, executes it
and returns the result.
"""
def __init__(self, body: Union[ClsDict,
Dict[type, Callable],
Iterable[Tuple[type, Callable]],
Iterable[Callable]]):
from typish.functions._instance_of import instance_of
if isinstance(body, ClsDict):
self.body = body
elif isinstance(body, dict):
self.body = ClsDict(body)
elif instance_of(body, Iterable[Callable]):
list_of_tuples = []
for func in body:
signature = inspect.signature(func)
params = list(signature.parameters.keys())
if not params:
raise TypeError('ClsFunction expects callables that take '
'at least one parameter, {} does not.'
.format(func.__name__))
first_param = signature.parameters[params[0]]
hint = first_param.annotation
key = Any if hint == Empty else hint
list_of_tuples.append((key, func))
self.body = ClsDict(OrderedDict(list_of_tuples))
elif instance_of(body, Iterable[Tuple[type, Callable]]):
self.body = ClsDict(OrderedDict(body))
else:
raise TypeError('ClsFunction expects a ClsDict or a dict that can '
'be turned to a ClsDict or an iterable of '
'callables.')
if not all(isinstance(value, Callable) for value in self.body.values()):
raise TypeError('ClsFunction expects a dict or ClsDict with only '
'callables as values.')
def understands(self, item: Any) -> bool:
"""
Check to see if this ClsFunction can take item.
:param item: the item that is checked.
:return: True if this ClsFunction can take item.
"""
try:
self.body[item]
return True
except KeyError:
return False
def __call__(self, *args, **kwargs):
if not args:
raise TypeError('ClsFunction must be called with at least 1 '
'positional argument.')
callable_ = self.body[args[0]]
try:
return callable_(*args, **kwargs)
except TypeError as err:
raise TypeError('Unable to call function for \'{}\': {}'
.format(args[0], err.args[0]))
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