from collections import (OrderedDict,
abc)
from inspect import (_ParameterKind,
signature as _signature)
from types import MethodType as _MethodType
from typing import (Any as _Any,
Callable as _Callable,
Iterable as _Iterable,
Union as _Union)
from . import (seekers as _seekers,
serializers as _serializers)
from .core.hints import (Constructor as _Constructor,
Initializer as _Initializer)
from .hints import (ArgumentSerializer as _ArgumentSerializer,
FieldSeeker as _FieldSeeker)
def generate_repr(method: _Union[_Constructor, _Initializer],
*,
argument_serializer: _ArgumentSerializer
= _serializers.simple,
field_seeker: _FieldSeeker = _seekers.simple,
prefer_keyword: bool = False,
skip_defaults: bool = False,
with_module_name: bool = False) -> _Callable[[_Any], str]:
"""
Generates ``__repr__`` method based on constructor/initializer parameters.
We are assuming that no parameters data
get thrown away during instance creation,
so we can re-create it after.
:param method:
constructor/initializer method
which parameters will be used in resulting representation.
:param argument_serializer: function that serializes argument to string.
:param field_seeker:
function that re-creates parameter value
based on class instance and name.
:param prefer_keyword:
flag that specifies
if positional-or-keyword parameters should be outputted
as keyword ones when possible.
:param skip_defaults:
flag that specifies
if optional parameters with default arguments should be skipped.
:param with_module_name:
flag that specifies if module name should be added.
>>> from reprit.base import generate_repr
>>> class Person:
... def __init__(self, name, *, address=None):
... self.name = name
... self.address = address
... __repr__ = generate_repr(__init__,
... skip_defaults=True)
>>> Person('Adrian')
Person('Adrian')
>>> Person('Mary', address='Somewhere on Earth')
Person('Mary', address='Somewhere on Earth')
>>> class ScoreBoard:
... def __init__(self, first, *rest):
... self.first = first
... self.rest = rest
... __repr__ = generate_repr(__init__,
... prefer_keyword=True)
>>> ScoreBoard(1)
ScoreBoard(first=1)
>>> ScoreBoard(1, 40)
ScoreBoard(1, 40)
>>> class Student:
... def __init__(self, name, group):
... self.name = name
... self.group = group
... __repr__ = generate_repr(__init__,
... with_module_name=True)
>>> Student('Kira', 132)
reprit.base.Student('Kira', 132)
>>> Student('Naomi', 248)
reprit.base.Student('Naomi', 248)
>>> from reprit import seekers
>>> class Account:
... def __init__(self, id_, *, balance=0):
... self.id = id_
... self.balance = balance
... __repr__ = generate_repr(__init__,
... field_seeker=seekers.complex_)
>>> Account(1)
Account(1, balance=0)
>>> Account(100, balance=-10)
Account(100, balance=-10)
>>> import json
>>> class Object:
... def __init__(self, value):
... self.value = value
... def serialized(self):
... return json.dumps(self.value)
... @classmethod
... def from_serialized(cls, serialized):
... return cls(json.loads(serialized))
... __repr__ = generate_repr(from_serialized)
>>> Object.from_serialized('0')
Object.from_serialized('0')
>>> Object.from_serialized('{"key": "value"}')
Object.from_serialized('{"key": "value"}')
"""
if with_module_name:
def to_class_name(cls: type) -> str:
return cls.__module__ + '.' + cls.__qualname__
else:
def to_class_name(cls: type) -> str:
return cls.__qualname__
unwrapped_method = (method.__func__
if isinstance(method, (classmethod, staticmethod))
else method)
method_name = unwrapped_method.__name__
parameters = OrderedDict(_signature(unwrapped_method).parameters)
if method_name == '__init__' or method_name == '__new__':
# remove `cls`/`self`
parameters.popitem(False)
def __repr__(self: _Any) -> str:
return (to_class_name(type(self))
+ '(' + ', '.join(to_arguments_strings(self)) + ')')
else:
if isinstance(method, classmethod):
# remove `cls`
parameters.popitem(False)
def __repr__(self: _Any) -> str:
return (to_class_name(type(self)) + '.' + method_name
+ '(' + ', '.join(to_arguments_strings(self)) + ')')
variadic_positional = next(
(parameter
for parameter in parameters.values()
if parameter.kind is _ParameterKind.VAR_POSITIONAL),
None)
to_keyword_string = '{}={}'.format
positional_only_parameters = [
parameter
for parameter in parameters.values()
if parameter.kind is _ParameterKind.POSITIONAL_ONLY
]
def to_arguments_strings(object_: _Any) -> _Iterable[str]:
variadic_positional_unset = (
variadic_positional is None
or not field_seeker(object_, variadic_positional.name))
positional_or_keyword_is_keyword = (prefer_keyword
and variadic_positional_unset)
fields = [seek_field(object_, name) for name in parameters.keys()]
for index, (parameter, field) in enumerate(zip(parameters.values(),
fields)):
kind = parameter.kind
show_parameter = (
not skip_defaults
or field is not parameter.default
or (kind is _ParameterKind.POSITIONAL_OR_KEYWORD
and not variadic_positional_unset)
or (kind is _ParameterKind.POSITIONAL_ONLY
and
(not variadic_positional_unset
or any(field is not parameter.default
for parameter, field
in zip(positional_only_parameters[index + 1:],
fields[index + 1:]))))
)
if show_parameter:
if kind is _ParameterKind.POSITIONAL_ONLY:
yield argument_serializer(field)
elif kind is _ParameterKind.POSITIONAL_OR_KEYWORD:
yield (to_keyword_string(parameter.name,
argument_serializer(field))
if positional_or_keyword_is_keyword
else argument_serializer(field))
elif kind is _ParameterKind.VAR_POSITIONAL:
yield from ((argument_serializer(field),)
# we don't want to exhaust iterator
if isinstance(field, abc.Iterator)
else map(argument_serializer, field))
elif kind is _ParameterKind.KEYWORD_ONLY:
yield to_keyword_string(parameter.name,
argument_serializer(field))
else:
yield from map(to_keyword_string, field.keys(),
map(argument_serializer, field.values()))
elif (not positional_or_keyword_is_keyword
and (kind is _ParameterKind.POSITIONAL_ONLY
or kind is _ParameterKind.POSITIONAL_OR_KEYWORD)):
positional_or_keyword_is_keyword = True
def seek_field(object_: _Any, name: str) -> _Any:
result = field_seeker(object_, name)
if isinstance(result, _MethodType) and result.__self__ is object_:
result = result()
return result
return __repr__