You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
145 lines
3.5 KiB
145 lines
3.5 KiB
# SPDX-License-Identifier: MIT
|
|
|
|
"""
|
|
Commonly useful converters.
|
|
"""
|
|
|
|
|
|
import typing
|
|
|
|
from ._compat import _AnnotationExtractor
|
|
from ._make import NOTHING, Factory, pipe
|
|
|
|
|
|
__all__ = [
|
|
"default_if_none",
|
|
"optional",
|
|
"pipe",
|
|
"to_bool",
|
|
]
|
|
|
|
|
|
def optional(converter):
|
|
"""
|
|
A converter that allows an attribute to be optional. An optional attribute
|
|
is one which can be set to ``None``.
|
|
|
|
Type annotations will be inferred from the wrapped converter's, if it
|
|
has any.
|
|
|
|
:param callable converter: the converter that is used for non-``None``
|
|
values.
|
|
|
|
.. versionadded:: 17.1.0
|
|
"""
|
|
|
|
def optional_converter(val):
|
|
if val is None:
|
|
return None
|
|
return converter(val)
|
|
|
|
xtr = _AnnotationExtractor(converter)
|
|
|
|
t = xtr.get_first_param_type()
|
|
if t:
|
|
optional_converter.__annotations__["val"] = typing.Optional[t]
|
|
|
|
rt = xtr.get_return_type()
|
|
if rt:
|
|
optional_converter.__annotations__["return"] = typing.Optional[rt]
|
|
|
|
return optional_converter
|
|
|
|
|
|
def default_if_none(default=NOTHING, factory=None):
|
|
"""
|
|
A converter that allows to replace ``None`` values by *default* or the
|
|
result of *factory*.
|
|
|
|
:param default: Value to be used if ``None`` is passed. Passing an instance
|
|
of `attrs.Factory` is supported, however the ``takes_self`` option
|
|
is *not*.
|
|
:param callable factory: A callable that takes no parameters whose result
|
|
is used if ``None`` is passed.
|
|
|
|
:raises TypeError: If **neither** *default* or *factory* is passed.
|
|
:raises TypeError: If **both** *default* and *factory* are passed.
|
|
:raises ValueError: If an instance of `attrs.Factory` is passed with
|
|
``takes_self=True``.
|
|
|
|
.. versionadded:: 18.2.0
|
|
"""
|
|
if default is NOTHING and factory is None:
|
|
raise TypeError("Must pass either `default` or `factory`.")
|
|
|
|
if default is not NOTHING and factory is not None:
|
|
raise TypeError(
|
|
"Must pass either `default` or `factory` but not both."
|
|
)
|
|
|
|
if factory is not None:
|
|
default = Factory(factory)
|
|
|
|
if isinstance(default, Factory):
|
|
if default.takes_self:
|
|
raise ValueError(
|
|
"`takes_self` is not supported by default_if_none."
|
|
)
|
|
|
|
def default_if_none_converter(val):
|
|
if val is not None:
|
|
return val
|
|
|
|
return default.factory()
|
|
|
|
else:
|
|
|
|
def default_if_none_converter(val):
|
|
if val is not None:
|
|
return val
|
|
|
|
return default
|
|
|
|
return default_if_none_converter
|
|
|
|
|
|
def to_bool(val):
|
|
"""
|
|
Convert "boolean" strings (e.g., from env. vars.) to real booleans.
|
|
|
|
Values mapping to :code:`True`:
|
|
|
|
- :code:`True`
|
|
- :code:`"true"` / :code:`"t"`
|
|
- :code:`"yes"` / :code:`"y"`
|
|
- :code:`"on"`
|
|
- :code:`"1"`
|
|
- :code:`1`
|
|
|
|
Values mapping to :code:`False`:
|
|
|
|
- :code:`False`
|
|
- :code:`"false"` / :code:`"f"`
|
|
- :code:`"no"` / :code:`"n"`
|
|
- :code:`"off"`
|
|
- :code:`"0"`
|
|
- :code:`0`
|
|
|
|
:raises ValueError: for any other value.
|
|
|
|
.. versionadded:: 21.3.0
|
|
"""
|
|
if isinstance(val, str):
|
|
val = val.lower()
|
|
truthy = {True, "true", "t", "yes", "y", "on", "1", 1}
|
|
falsy = {False, "false", "f", "no", "n", "off", "0", 0}
|
|
try:
|
|
if val in truthy:
|
|
return True
|
|
if val in falsy:
|
|
return False
|
|
except TypeError:
|
|
# Raised when "val" is not hashable (e.g., lists)
|
|
pass
|
|
raise ValueError("Cannot convert value to bool: {}".format(val))
|