Spaces:
Running
Running
File size: 3,622 Bytes
375a1cf |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 |
# 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:
msg = "Must pass either `default` or `factory`."
raise TypeError(msg)
if default is not NOTHING and factory is not None:
msg = "Must pass either `default` or `factory` but not both."
raise TypeError(msg)
if factory is not None:
default = Factory(factory)
if isinstance(default, Factory):
if default.takes_self:
msg = "`takes_self` is not supported by default_if_none."
raise ValueError(msg)
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
msg = f"Cannot convert value to bool: {val}"
raise ValueError(msg)
|