-
-
Notifications
You must be signed in to change notification settings - Fork 921
/
config.py
149 lines (124 loc) Β· 4.5 KB
/
config.py
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
146
147
148
149
import os
import typing
from collections.abc import MutableMapping
from pathlib import Path
class undefined:
pass
class EnvironError(Exception):
pass
class Environ(MutableMapping):
def __init__(self, environ: typing.MutableMapping = os.environ):
self._environ = environ
self._has_been_read: typing.Set[typing.Any] = set()
def __getitem__(self, key: typing.Any) -> typing.Any:
self._has_been_read.add(key)
return self._environ.__getitem__(key)
def __setitem__(self, key: typing.Any, value: typing.Any) -> None:
if key in self._has_been_read:
raise EnvironError(
f"Attempting to set environ['{key}'], but the value has already been "
"read."
)
self._environ.__setitem__(key, value)
def __delitem__(self, key: typing.Any) -> None:
if key in self._has_been_read:
raise EnvironError(
f"Attempting to delete environ['{key}'], but the value has already "
"been read."
)
self._environ.__delitem__(key)
def __iter__(self) -> typing.Iterator:
return iter(self._environ)
def __len__(self) -> int:
return len(self._environ)
environ = Environ()
T = typing.TypeVar("T")
class Config:
def __init__(
self,
env_file: typing.Optional[typing.Union[str, Path]] = None,
environ: typing.Mapping[str, str] = environ,
env_prefix: str = "",
) -> None:
self.environ = environ
self.env_prefix = env_prefix
self.file_values: typing.Dict[str, str] = {}
if env_file is not None and os.path.isfile(env_file):
self.file_values = self._read_file(env_file)
@typing.overload
def __call__(self, key: str, *, default: None) -> typing.Optional[str]:
...
@typing.overload
def __call__(self, key: str, cast: typing.Type[T], default: T = ...) -> T:
...
@typing.overload
def __call__(
self, key: str, cast: typing.Type[str] = ..., default: str = ...
) -> str:
...
@typing.overload
def __call__(
self,
key: str,
cast: typing.Callable[[typing.Any], T] = ...,
default: typing.Any = ...,
) -> T:
...
@typing.overload
def __call__(
self, key: str, cast: typing.Type[str] = ..., default: T = ...
) -> typing.Union[T, str]:
...
def __call__(
self,
key: str,
cast: typing.Optional[typing.Callable] = None,
default: typing.Any = undefined,
) -> typing.Any:
return self.get(key, cast, default)
def get(
self,
key: str,
cast: typing.Optional[typing.Callable] = None,
default: typing.Any = undefined,
) -> typing.Any:
key = self.env_prefix + key
if key in self.environ:
value = self.environ[key]
return self._perform_cast(key, value, cast)
if key in self.file_values:
value = self.file_values[key]
return self._perform_cast(key, value, cast)
if default is not undefined:
return self._perform_cast(key, default, cast)
raise KeyError(f"Config '{key}' is missing, and has no default.")
def _read_file(self, file_name: typing.Union[str, Path]) -> typing.Dict[str, str]:
file_values: typing.Dict[str, str] = {}
with open(file_name) as input_file:
for line in input_file.readlines():
line = line.strip()
if "=" in line and not line.startswith("#"):
key, value = line.split("=", 1)
key = key.strip()
value = value.strip().strip("\"'")
file_values[key] = value
return file_values
def _perform_cast(
self, key: str, value: typing.Any, cast: typing.Optional[typing.Callable] = None
) -> typing.Any:
if cast is None or value is None:
return value
elif cast is bool and isinstance(value, str):
mapping = {"true": True, "1": True, "false": False, "0": False}
value = value.lower()
if value not in mapping:
raise ValueError(
f"Config '{key}' has value '{value}'. Not a valid bool."
)
return mapping[value]
try:
return cast(value)
except (TypeError, ValueError):
raise ValueError(
f"Config '{key}' has value '{value}'. Not a valid {cast.__name__}."
)