org.epics.pvmanager
Class TypeSupport<T>

java.lang.Object
  org.epics.pvmanager.TypeSupport<T>

Type Parameters:

T - the type for which to add support

Direct Known Subclasses:

NotificationSupport, TimeSupport

public abstract class TypeSupport<T>
extends java.lang.Object

Implements the mechanism for registering different types so that the library knows how to handle them.

For a type to be usable by the library it needs to be defined:

• How to copy - since values given to the UI should be modified only within the UI thread, it follows that new values cannot be prepared "in place", on the same object that was given to the UI. At notification, there will be then two copies, the old and the new, and in need to be clear how the new copy should be delivered. (e.g. just pass the new copy, modify the old object in place, etc...).
• When to notify - by comparing elements of the value, it should decide on what condition the old value need to be modified and the UI should be notified of the change.

Author:

carcassi

TypeSupport

public TypeSupport(java.lang.Class<T> type,
                   java.lang.Class<? extends TypeSupport> typeSupportFamily)

Creates a new type support of the given type

Parameters:

type - the type on which support is defined

typeSupportFamily - the kind of support is being defined

addTypeSupport

public static void addTypeSupport(TypeSupport<?> typeSupport)

Adds type support for the given class. The type support added will apply to the given class and all of its subclasses. Support of the same family cannot be added twice and will cause an exception. Support for the more specific subclass overrides support for the more abstract class. A class cannot have two types support in the same family coming from two different and unrelated interfaces.

Parameters:

typeSupport - the support to add

isTypeSupported

public static boolean isTypeSupported(java.lang.Class<? extends TypeSupport> typeSupportFamily,
                                      java.lang.Class<?> type)

Checks whether the type is supported directly or through one of the supertypes.

Parameters:

type - type to check support for

typeSupportFamily - the family in which to look for

Returns:

true if supported

Throws:

java.lang.RuntimeException - if multiple conflicting support is found

isTypeDirectlySupported

public static boolean isTypeDirectlySupported(java.lang.Class<? extends TypeSupport> typeSupportFamily,
                                              java.lang.Class<?> type)

Checks whether the type is supported on the same exact type.

Parameters:

type - type to check support for

typeSupportFamily - the family in which to look for

Returns:

true if supported

findTypeSupportFor

protected static <T> TypeSupport<T> findTypeSupportFor(java.lang.Class<? extends TypeSupport> supportFamily,
                                                       java.lang.Class<T> typeClass)

Calculates and caches the type support for a particular class, so that introspection does not occur at every call.

Find the supports for all supertypes. If multiple supports for different supertypes are found, and there isn't a most specific one (i.e. one that implements all the others) then an exception is thrown.

Type Parameters:

T - the type to retrieve support for

Parameters:

supportFamily - the support family for which to find support

typeClass - the class of the type

Returns:

the support for the type or null

Throws:

java.lang.RuntimeException - if multiple conflicting support is found

typeSupportsFor

protected static <T extends TypeSupport<?>> java.util.Collection<T> typeSupportsFor(java.lang.Class<T> supportFamily)

getTypeSupportFamily

protected java.lang.Class<? extends TypeSupport> getTypeSupportFamily()

Defines which type of support is implementing, notification or time.

Returns:

the support family

getType

protected java.lang.Class<T> getType()

Defines on which class the support is defined.