StorageClass

class lsst.daf.butler.StorageClass(name: Optional[str] = None, pytype: Optional[Union[Type, str]] = None, components: Optional[Dict[str, lsst.daf.butler.StorageClass]] = None, derivedComponents: Optional[Dict[str, lsst.daf.butler.StorageClass]] = None, parameters: Optional[Union[Sequence, Set]] = None, delegate: Optional[str] = None)

Bases: object

Class describing how a label maps to a particular Python type.

Parameters

namestr

Name to use for this class.

pytypetype or str

Python type (or name of type) to associate with the StorageClass

componentsdict, optional

dict mapping name of a component to another StorageClass.

derivedComponentsdict, optional

dict mapping name of a derived component to another StorageClass.

parametersSequence or Set

Parameters understood by this StorageClass that can control reading of data from datastores.

delegatestr, optional

Fully qualified name of class supporting assembly and disassembly of a pytype instance.

Attributes Summary

components	Return the components associated with this StorageClass.
defaultDelegateName
delegateClass	Class to use to delegate type-specific actions.
derivedComponents	Return derived components associated with StorageClass.
parameters	Return set of names of supported parameters.
pytype	Return Python type associated with this StorageClass.

Methods Summary

allComponents()	Return all defined components.
delegate()	Return an instance of a storage class delegate.
filterParameters(parameters[, subset])	Filter out parameters that are not known to this StorageClass.
isComposite()	Return Boolean indicating whether this is a composite or not.
knownParameters()	Return set of all parameters known to this StorageClass.
validateInstance(instance)	Check that the supplied Python object has the expected Python type.
validateParameters([parameters])	Check that the parameters are known to this StorageClass.

Attributes Documentation

components

Return the components associated with this StorageClass.

defaultDelegateName: str = 'lsst.daf.butler.core.storageClassDelegate.StorageClassDelegate'

delegateClass

Class to use to delegate type-specific actions.

derivedComponents

Return derived components associated with StorageClass.

parameters

Return set of names of supported parameters.

pytype

Return Python type associated with this StorageClass.

Methods Documentation

allComponents() → Mapping[str, lsst.daf.butler.StorageClass]

Return all defined components.

This mapping includes all the derived and read/write components for the corresponding storage class.

Returns

compdict of [str, StorageClass]

The component name to storage class mapping.

delegate() → lsst.daf.butler.StorageClassDelegate

Return an instance of a storage class delegate.

Returns

delegateStorageClassDelegate

Instance of the delegate associated with this StorageClass. The delegate is constructed with this StorageClass.

Raises

TypeError

This StorageClass has no associated delegate.

filterParameters(parameters: Dict[str, Any], subset: Optional[Collection] = None) → Dict[str, Any]

Filter out parameters that are not known to this StorageClass.

Parameters

parametersdict, optional

Candidate parameters. Can be None if no parameters have been provided.

subsetCollection, optional

Subset of supported parameters that the caller is interested in using. The subset must be known to the StorageClass if specified. If None the supplied parameters will all be checked, else only the keys in this set will be checked.

Returns

filtereddict

Valid parameters. Empty dict if none are suitable.

Raises

ValueError

Raised if the provided subset is not a subset of the supported parameters or if it is an empty set.

isComposite() → bool

Return Boolean indicating whether this is a composite or not.

Returns

isCompositebool

True if this StorageClass is a composite, False otherwise.

knownParameters() → Set[str]

Return set of all parameters known to this StorageClass.

The set includes parameters understood by components of a composite.

Returns

knownset

All parameter keys of this StorageClass and the component storage classes.

validateInstance(instance: Any) → bool

Check that the supplied Python object has the expected Python type.

Parameters

instanceobject

Object to check.

Returns

isOkbool

True if the supplied instance object can be handled by this StorageClass, False otherwise.

validateParameters(parameters: Optional[Collection] = None) → None

Check that the parameters are known to this StorageClass.

Does not check the values.

Parameters

parametersCollection, optional

Collection containing the parameters. Can be dict-like or set-like. The parameter values are not checked. If no parameters are supplied, always returns without error.

Raises

KeyError

Some parameters are not understood by this StorageClass.