thatway 0.6.0

1. Configure directly

Settings can be set directly on the config object.

>>> from thatway import config, Setting
>>> config.a = Setting(3)
>>> config.a
3
>>> config.nested.b = Setting("nested")
>>> config.nested.b
'nested'

Trying to set an entry in the config without a setting raises an exception.

>>> from thatway import config
>>> config.new_value = 3
Traceback (most recent call last):
...
thatway.base.ConfigException: Only Settings can be inserted in the Config

2. Configure object attributes

Settings can be set as object attributes.

>>> from thatway import Setting
>>> class Obj:
...     attribute = Setting("my value")
>>> obj = Obj()
>>> obj.attribute
'my value'

3. Configuration locking

Settings cannot be accidentally modified. Once they’re set, they’re set until the config’s update or load methods are used.

>>> from thatway import Setting
>>> config.b = Setting(3)
>>> config.b
3
>>> config.b = Setting(5)  # oops!
Traceback (most recent call last):
...
thatway.base.ConfigException: Entry 'b' already in the Config--use a Config.update or load method to change its value.
>>> config.b = 5  # oops!
Traceback (most recent call last):
...
thatway.base.ConfigException: Only Settings can be inserted in the Config
>>> config.update({'b': 5})
>>> config.b
5

The one exception is that settings defined on a class can be replaced on the class itself–not a class instance. This is because settings act as descriptors for classes.

4. Type Enforcement

Setting types are checked and maintained with either the setting’s value type, or the allowed_types optional argument.

>>> from thatway import Setting
>>> config.c = Setting(5, allowed_types=(int, str))
>>> config.update({'c': 'my new c value'})
>>> config.c
'my new c value'
>>> config.d = Setting(6)
>>> config.update({'d': 'my new d value'})
Traceback (most recent call last):
...
ValueError: Could not convert 'my new d value' into any of the following types: [<class 'int'>]

6. Missing Settings

Trying to update a setting that doesn’t exist is not possible. This behavior is designed to avoid trying to change a setting but using an incorrect setting name and location.

>>> from thatway import Setting
>>> config.update({'e': 'unassigned'})  # 'f' doesn't exist in config
Traceback (most recent call last):
...
KeyError: "Tried assigning setting with name 'e' which does not exist in the Config"

7. Immutable Settings Values

Setting values can only be immutable objects.

>>> from thatway import Setting
>>> config.cli.color = Setting(True)
>>> config.cli.default_filenames = Setting(('a.html', 'b.html'))
>>> config.cli.value_list = Setting([1, 2])  # lists are mutable
Traceback (most recent call last):
...
thatway.base.ConfigException: Setting value '[1, 2]' must be immutable

1. Setting descriptions

Settings can include descriptions.

>>> from thatway import Setting
>>> config.e = Setting(4, desc="The 'e' attribute")

2. Yaml processing

Settings can be dumped in yaml.

config.dumps_yaml()

Obj:
  a: 1
b: name  # The 'b' setting
nested:
  c: true

And yaml strings or files can be loaded with config.loads_yaml(string) and config.load_yaml(filepath), respectively.

3. Toml processing

Settings can be dumped in toml.

config.dumps_toml()

[Obj]
  a = 1
b = "name"  # The 'b' setting
[nested]
  c = true

And toml strings or files can be loaded with config.loads_toml(string) and config.load_toml(filepath), respectively.