ListField

class lsst.pex.config.ListField(doc, dtype=None, default=None, optional=False, listCheck=None, itemCheck=None, length=None, minLength=None, maxLength=None, deprecated=None)

Bases: Field[List[FieldTypeVar]], Generic[FieldTypeVar]

A configuration field (Field subclass) that contains a list of values of a specific type.

Parameters

docstr

A description of the field.

dtypeclass, optional

The data type of items in the list. Optional if supplied as typing argument to the class.

defaultsequence, optional

The default items for the field.

optionalbool, optional

Set whether the field is optional. When False, lsst.pex.config.Config.validate will fail if the field’s value is None.

listCheckcallable, optional

A callable that validates the list as a whole.

itemCheckcallable, optional

A callable that validates individual items in the list.

lengthint, optional

If set, this field must contain exactly length number of items.

minLengthint, optional

If set, this field must contain at least minLength number of items.

maxLengthint, optional

If set, this field must contain no more than maxLength number of items.

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 DictField Field RangeField RegistryField

Methods Summary

toDict(instance)	Convert the value of this field to a plain list.
validate(instance)	Validate the field.

Methods Documentation

toDict(instance)

Convert the value of this field to a plain list.

lsst.pex.config.Config.toDict is the primary user of this method.

Parameters

instancelsst.pex.config.Config

The config instance that contains this field.

Returns

list

Plain list of items, or None if the field is not set.

validate(instance)

Validate the field.

Parameters

instancelsst.pex.config.Config

The config instance that contains this field.

Raises

lsst.pex.config.FieldValidationError

Raised if:

• The field is not optional, but the value is None.

• The list itself does not meet the requirements of the length, minLength, or maxLength attributes.

• The listCheck callable returns False.

Notes

Individual item checks (itemCheck) are applied when each item is set and are not re-checked by this method.