MappingFactory

class lsst.daf.butler.MappingFactory(refType)

Bases: object

Register the mapping of some key to a python type and retrieve instances.

Enables instances of these classes to be retrieved from the factory later. The class can be specified as an object, class or string. If the key is an object it is converted to a string by accessing a name attribute.

Parameters:

refType : type

Python reference type to use to ensure that items stored in the registry create instance objects of the correct class. Subclasses of this type are allowed. Using None disables the check.

Methods Summary

getFromRegistry(*targetClasses)	Get a new instance of the object stored in the registry.
placeInRegistry(registryKey, typeName)	Register a class name with the associated type.

Methods Documentation

getFromRegistry(*targetClasses)

Get a new instance of the object stored in the registry.

Parameters:

*targetClasses : str or objects supporting name attribute

Each item is tested in turn until a match is found in the registry. Items with None value are skipped.

Returns:

instance : object

Instance of class stored in registry associated with the first matching target class.

Raises:

KeyError

None of the supplied target classes match an item in the registry.

placeInRegistry(registryKey, typeName)

Register a class name with the associated type.

The type name provided is validated against the reference class, refType attribute, if defined.

Parameters:

registryKey : str or object supporting name attribute.

Item to associate with the provided type.

typeName : str or Python type

Identifies a class to associate with the provided key.

Raises:

ValueError

If instance of class is not of the expected type.

KeyError

If item is already registered and has different value.