confattr.config module

Bases: Generic[T]

Each instance of this class represents a setting which can be changed in a config file.

This class implements the descriptor protocol to return value if an instance of this class is accessed as an instance attribute. If you want to get this object you need to access it as a class attribute.

Parameters:

key¶ – The name of this setting in the config file
default¶ – The default value of this setting
type¶ – How to parse, format and complete a value. Usually this is determined automatically based on default. But if default is an empty list the item type cannot be determined automatically so that this argument must be passed explicitly. This also gives the possibility to format a standard type differently e.g. as Hex. It is not permissible to reuse the same object for different settings, otherwise AbstractFormatter.set_config_key() will throw an exception.
unit¶ – The unit of an int or float value (only if type is None)
allowed_values¶ – The possible values this setting can have. Values read from a config file or an environment variable are checked against this. The default value is not checked. (Only if type is None.)
help¶ – A description of this setting
parent¶ – Applies only if this is part of a DictConfig

T can be one of:

str
int
float
bool
a subclass of enum.Enum (the value used in the config file is the name in lower case letters with hyphens instead of underscores)
a class where __str__() returns a string representation which can be passed to the constructor to create an equal object. A help which is written to the config file must be provided as a str in the class attribute help or by adding it to Primitive.help_dict. If that class has a str attribute type_name this is used instead of the class name inside of config file.
a list of any of the afore mentioned data types. The list may not be empty when it is passed to this constructor so that the item type can be derived but it can be emptied immediately afterwards. (The type of the items is not dynamically enforced—that’s the job of a static type checker—but the type is mentioned in the help.)

Raises:

ValueError – if key is not unique
TypeError – if default is an empty list/set because the first element is used to infer the data type to which a value given in a config file is converted
TypeError – if this setting is a number or a list of numbers and unit is not given
TimingError – if this setting is defined after creating a ConfigFile object without passing a list or set of settings to config_instances

default_config_id = 'general'

get_value(config_id: ConfigId | None) → T

Returns:: value

This getter is only to have a common interface for Config and MultiConfig

help: str | dict[T, str] | None: A description of this setting or a description for each allowed value.

instances: dict[str, Config[Any]] = {}: A mapping of all Config instances. The key in the mapping is the key attribute. The value is the Config instance. New Config instances add themselves automatically in their constructor.

is_value_valid() → bool

Returns:: true unless the value of an ExplicitConfig instance has not been set yet

classmethod iter_instances() → Iterator[Config[Any] | DictConfig[Any, Any]]: Yield the instances in instances but merge DictConfig items to a single DictConfig instance so that they can be sorted differently.

property key: str: The name of this setting which is used in the config file. This must be unique. You can change this attribute but only as long as no ConfigFile or ConfigManager has been instantiated.

classmethod pop_key_changer() → Callable[[str], str]: Undo the last call to push_key_changer().

classmethod push_key_changer(callback: Callable[[str], str]) → None

Modify the key of all settings which will be defined after calling this method.

Call this before an import and pop_key_changer() after it if you are unhappy with the keys of a third party library. If you import that library in different modules make sure you do this at the import which is executed first.

Parameters:: callback¶ – A function which takes the key as argument and returns the modified key.

set_value(config_id: ConfigId | None, value: T) → None: This method is just to provide a common interface for Config and MultiConfig. If you know that you are dealing with a normal Config you can set value directly.

type: AbstractFormatter[T]: Information about data type, unit and allowed values for value and methods how to parse, format and complete it.

value: T: The value of this setting.

wants_to_be_exported() → bool

class confattr.config.ConfigId

An identifier to specify which value of a MultiConfig or MultiDictConfig should be used for a certain object.

alias of str

class confattr.config.DictConfig(key_prefix: str, default_values: dict[T_KEY, T], *, type: CopyableAbstractFormatter[T] | None = None, ignore_keys: Container[T_KEY] = {}, unit: str | None = None, allowed_values: Sequence[T] | dict[str, T] | None = None, help: str | None = None, sort: Sort = Sort.NAME)

Bases: Generic[T_KEY, T]

A container for several settings which belong together. Except for __eq__() and __ne__() it behaves like a normal Mapping but internally the items are stored in Config instances.

In contrast to a Config instance it does not make a difference whether an instance of this class is accessed as a type or instance attribute.

Parameters:

key_prefix¶ – A common prefix which is used by format_key() to generate the key by which the setting is identified in the config file
default_values¶ – The content of this container. A Config instance is created for each of these values (except if the key is contained in ignore_keys). See format_key().
type¶ – How to parse, format and complete a value. Usually this is determined automatically based on default_values. But if you want more control you can implement your own class and pass it to this parameter.
ignore_keys¶ – All items which have one of these keys are not stored in a Config instance, i.e. cannot be set in the config file.
unit¶ – The unit of all items (only if type is None)
allowed_values¶ – The possible values these settings can have. Values read from a config file or an environment variable are checked against this. The default_values are not checked. (Only if type is None.)
help¶ – A help for all items
sort¶ – How to sort the items of this dictionary in the config file/documentation

Raises:

ValueError – if a key is not unique

class Sort(*values)

Bases: Enum

ENUM_VALUE = 2

NAME = 1

NONE = 3

format_key(key: T_KEY) → str

Generate a key by which the setting can be identified in the config file based on the dict key by which the value is accessed in the python code.

Returns:: key_prefix + dot + key

get(key: T_KEY) → T | None
get(key: T_KEY, default: T_DEFAULT) → T | T_DEFAULT

items() → Iterator[tuple[T_KEY, T]]

iter_configs() → Iterator[Config[T]]: Iterate over the Config instances contained in this dict, sorted by the argument passed to sort in the constructor

keys() → Iterator[T_KEY]

new_config(key: str, default: T, *, unit: str | None, help: str | dict[T, str] | None) → Config[T]: Create a new Config instance to be used internally

values() → Iterator[T]

Bases: Config[T]

A setting without a default value which requires the user to explicitly set a value in the config file or pass it as command line argument.

You can use is_value_valid() in order to check whether this config has a value or not.

If you try to use the value before it has been set: If you try to access the config as instance attribute (object.config) a TypeError is thrown. Otherwise (config.value) None is returned.

Parameters:

key¶ – The name of this setting in the config file
type¶ – How to parse, format and complete a value. Any class which can be passed to Primitive or an object of a subclass of AbstractFormatter.
unit¶ – The unit of an int or float value (only if type is not an AbstractFormatter)
allowed_values¶ – The possible values this setting can have. Values read from a config file or an environment variable are checked against this. The default value is not checked. (Only if type is not an AbstractFormatter.)
help¶ – A description of this setting
parent¶ – Applies only if this is part of a DictConfig

is_value_valid() → bool

Returns:: true unless the value of an ExplicitConfig instance has not been set yet

class confattr.config.InstanceSpecificDictMultiConfig(mdc: MultiDictConfig[T_KEY, T], config_id: ConfigId)

Bases: Generic[T_KEY, T]

An intermediate instance which is returned when accsessing a MultiDictConfig as an instance attribute. Can be indexed like a normal dict.

Bases: Config[T]

A setting which can have different values for different objects.

This class implements the descriptor protocol to return one of the values in values depending on a config_id attribute of the owning object if an instance of this class is accessed as an instance attribute. If there is no value for the config_id in values value is returned instead. If the owning instance does not have a config_id attribute an AttributeError is raised.

In the config file a group can be opened with [config-id]. Then all following set commands set the value for the specified config id.

Parameters:

key¶ – The name of this setting in the config file
default¶ – The default value of this setting
help¶ – A description of this setting
type¶ – How to parse, format and complete a value. Usually this is determined automatically based on default. But if default is an empty list the item type cannot be determined automatically so that this argument must be passed explicitly. This also gives the possibility to format a standard type differently e.g. as Hex. It is not permissible to reuse the same object for different settings, otherwise AbstractFormatter.set_config_key() will throw an exception.
unit¶ – The unit of an int or float value (only if type is None)
allowed_values¶ – The possible values this setting can have. Values read from a config file or an environment variable are checked against this. The default value is not checked. (Only if type is None.)
parent¶ – Applies only if this is part of a MultiDictConfig
check_config_id¶ – Is called every time a value is set in the config file (except if the config id is default_config_id—that is always allowed). The callback should raise a ParseException if the config id is invalid.

check_config_id: Callable[[MultiConfig[T], ConfigId], None] | None: The callable which has been passed to the constructor as check_config_id

config_ids: list[ConfigId] = []: A list of all config ids for which a value has been set in any instance of this class (regardless of via code or in a config file and regardless of whether the value has been deleted later on). This list is cleared by reset().

get_value(config_id: ConfigId | None) → T

Returns:: The corresponding value from values if config_id is contained or value otherwise

classmethod reset() → None: Clear config_ids and clear values for all instances in Config.instances

set_value(config_id: ConfigId | None, value: T) → None

Check config_id by calling check_config_id() and set the value for the object(s) identified by config_id.

If you know that config_id is valid you can also change the items of values directly. That is especially useful in test automation with pytest.MonkeyPatch.setitem().

If you want to set the default value you can also set value directly.

Parameters:

config_id¶ – Identifies the object(s) for which value is intended. None is equivalent to default_config_id.
value¶ – The value to be assigned for the object(s) identified by config_id.

value: T: Stores the default value which is used if no value for the object is defined in values.

values: dict[ConfigId, T]: Stores the values for specific objects.

class confattr.config.MultiDictConfig(key_prefix: str, default_values: dict[T_KEY, T], *, type: CopyableAbstractFormatter[T] | None = None, ignore_keys: Container[T_KEY] = {}, unit: str | None = None, allowed_values: Sequence[T] | dict[str, T] | None = None, help: str | None = None, check_config_id: Callable[[MultiConfig[T], ConfigId], None] | None = None)

Bases: DictConfig[T_KEY, T]

A container for several settings which can have different values for different objects.

This is essentially a DictConfig using MultiConfig instead of normal Config. However, in order to return different values depending on the config_id of the owning instance, it implements the descriptor protocol to return an InstanceSpecificDictMultiConfig if it is accessed as an instance attribute.

Parameters:

key_prefix¶ – A common prefix which is used by format_key() to generate the key by which the setting is identified in the config file
default_values¶ – The content of this container. A Config instance is created for each of these values (except if the key is contained in ignore_keys). See format_key().
type¶ – How to parse, format and complete a value. Usually this is determined automatically based on default_values. But if you want more control you can implement your own class and pass it to this parameter.
ignore_keys¶ – All items which have one of these keys are not stored in a Config instance, i.e. cannot be set in the config file.
unit¶ – The unit of all items (only if type is None)
allowed_values¶ – The possible values these settings can have. Values read from a config file or an environment variable are checked against this. The default_values are not checked. (Only if type is None.)
help¶ – A help for all items
check_config_id¶ – Is passed through to MultiConfig

Raises:

ValueError – if a key is not unique

new_config(key: str, default: T, *, unit: str | None, help: str | dict[T, str] | None) → MultiConfig[T]: Create a new Config instance to be used internally

exception confattr.config.TimingError

Bases: Exception

Is raised when trying to instantiate Config if a ConfigFile has been instantiated before without passing an explicit list or set to config_instances or when trying to change a key after creating any ConfigFile because such changes would otherwise be silently ignored by that ConfigFile.

confattr.config.is_mapping_with_enum_keys(m: Mapping[Any, T]) → TypeGuard[Mapping[Enum, T]]