DictField¶

class lsst.pex.config.DictField(doc, keytype=None, itemtype=None, default=None, optional=False, dictCheck=None, itemCheck=None, deprecated=None)¶

Bases: Field[Dict[KeyTypeVar, ItemTypeVar]], Generic[KeyTypeVar, ItemTypeVar]

A configuration field (Field subclass) that maps keys and values.

The types of both items and keys are restricted to these builtin types: int, float, complex, bool, and str). All keys share the same type and all values share the same type. Keys can have a different type from values.

Parameters:

docstr: A documentation string that describes the configuration field.
keytype{int, float, complex, bool, str}, optional: The type of the mapping keys. All keys must have this type. Optional if keytype and itemtype are supplied as typing arguments to the class.
itemtype{int, float, complex, bool, str}, optional: Type of the mapping values. Optional if keytype and itemtype are supplied as typing arguments to the class.
defaultdict, optional: The default mapping.
optionalbool, optional: If True, the field doesn’t need to have a set value.
dictCheckcallable: A function that validates the dictionary as a whole.
itemCheckcallable: A function that validates individual mapping values.
deprecatedNone or str, optional: A description of why this Field is deprecated, including removal date. If not None, the string is appended to the docstring for this Field.

See also

ChoiceField
ConfigChoiceField
ConfigDictField
ConfigField
ConfigurableField
Field
ListField
RangeField
RegistryField

Examples

This field maps has str keys and int values:

>>> from lsst.pex.config import Config, DictField
>>> class MyConfig(Config):
...     field = DictField(
...         doc="Example string-to-int mapping field.",
...         keytype=str, itemtype=int,
...         default={})
...
>>> config = MyConfig()
>>> config.field['myKey'] = 42
>>> print(config.field)
{'myKey': 42}

Attributes Summary

supportedTypes

Supported data types for field values (set of types).

Methods Summary

`freeze`(instance)	Make this field read-only (for internal use only).
`rename`(instance)	Rename the field in a `Config` (for internal use only).
`save`(outfile, instance)	Save this field to a file (for internal use only).
`toDict`(instance)	Convert this field's key-value pairs into a regular `dict`.
`validate`(instance)	Validate the field's value (for internal use only).

Attributes Documentation

supportedTypes = {<class 'bool'>, <class 'int'>, <class 'str'>, <class 'float'>, <class 'complex'>}¶: Supported data types for field values (set of types).

Methods Documentation

freeze(instance)¶

Make this field read-only (for internal use only).

Parameters:

instancelsst.pex.config.Config: The config instance that contains this field.

Notes

Freezing is only relevant for fields that hold subconfigs. Fields which hold subconfigs should freeze each subconfig.

Subclasses should implement this method.

rename(instance)¶

Rename the field in a Config (for internal use only).

Parameters:

instancelsst.pex.config.Config: The config instance that contains this field.

Notes

This method is invoked by the lsst.pex.config.Config object that contains this field and should not be called directly.

Renaming is only relevant for Field instances that hold subconfigs. Fields that hold subconfigs should rename each subconfig with the full field name as generated by lsst.pex.config.config._joinNamePath.

save(outfile, instance)¶

Save this field to a file (for internal use only).

Parameters:

outfilefile-like object: A writeable field handle.
instanceConfig: The Config instance that contains this field.

Notes

This method is invoked by the Config object that contains this field and should not be called directly.

The output consists of the documentation string (lsst.pex.config.Field.doc) formatted as a Python comment. The second line is formatted as an assignment: {fullname}={value}.

This output can be executed with Python.

toDict(instance)¶

Convert this field’s key-value pairs into a regular dict.

Parameters:

instancelsst.pex.config.Config: The configuration that contains this field.

Returns:

resultdict or None: If this field has a value of None, then this method returns None. Otherwise, this method returns the field’s value as a regular Python dict.

validate(instance)¶

Validate the field’s value (for internal use only).

Parameters:

instancelsst.pex.config.Config: The configuration that contains this field.

Returns:

isValidbool: True is returned if the field passes validation criteria (see Notes). Otherwise False.

Notes

This method validates values according to the following criteria:

A non-optional field is not None.
If a value is not None, is must pass the ConfigField.dictCheck user callback functon.

Individual item checks by the ConfigField.itemCheck user callback function are done immediately when the value is set on a key. Those checks are not repeated by this method.

Navigation

DictField¶