attrs/attr/_make.py

114 lines
3.0 KiB
Python

# -*- coding: utf-8 -*-
from __future__ import absolute_import, division, print_function
from ._dunders import (
NOTHING,
_add_cmp,
_add_hash,
_add_init,
_add_repr,
)
class Attribute(object):
def __init__(self, name, default_value, default_factory):
self.name = name
self.default_value = default_value
self.default_factory = default_factory
@classmethod
def from_counting_attr(cl, name, ca):
return cl(
name=name,
default_value=ca.default_value,
default_factory=ca.default_factory,
)
_a = ["name", "default_value", "default_factory"]
Attribute = _add_cmp(_add_repr(Attribute, attrs=_a), attrs=_a)
class _CountingAttr(object):
__attrs_attrs__ = [
Attribute(name=name, default_value=NOTHING, default_factory=NOTHING)
for name
in ("counter", "default_value", "default_factory",)
]
counter = 0
def __init__(self, default_value=NOTHING, default_factory=NOTHING):
_CountingAttr.counter += 1
self.counter = _CountingAttr.counter
self.default_value = default_value
self.default_factory = default_factory
_CountingAttr = _add_cmp(_add_repr(_CountingAttr))
def _make_attr(default_value=NOTHING, default_factory=NOTHING):
"""
Create a new attribute on a class.
Does nothing unless the class is also decorated with ``@attr.s``!
"""
if default_value is not NOTHING and default_factory is not NOTHING:
raise ValueError(
"Specifying both default_value and default_factory is "
"ambiguous."
)
return _CountingAttr(
default_value=default_value,
default_factory=default_factory,
)
def _get_attrs(cl):
"""
Return list of tuples of `(name, _Attr)`.
"""
attrs = []
for name, instance in sorted((
(n, i) for n, i in cl.__dict__.items()
if isinstance(i, _CountingAttr)
), key=lambda e: e[1].counter):
attrs.append((name, instance))
return attrs
def s(maybe_cl=None, add_repr=True, add_cmp=True, add_hash=True,
add_init=True):
# attrs_or class type depends on the usage of the decorator.
# It's a class if it's used as `@s` but ``None`` (or a value
# passed) if used as `@s()`.
if isinstance(maybe_cl, type):
cl = maybe_cl
cl.__attrs_attrs__ = [
Attribute.from_counting_attr(name=name, ca=ca)
for name, ca in _get_attrs(cl)
]
return _add_init(_add_hash(_add_cmp(_add_repr(cl))))
else:
def wrap(cl):
cl.__attrs_attrs__ = [
Attribute.from_counting_attr(name=name, ca=ca)
for name, ca in _get_attrs(cl)
]
if add_repr is True:
cl = _add_repr(cl)
if add_cmp is True:
cl = _add_cmp(cl)
if add_hash is True:
cl = _add_hash(cl)
if add_init is True:
cl = _add_init(cl)
return cl
return wrap