Class Scopelet<S extends Scopelet<S>>

java.lang.Object

org.microbean.scopelet.Scopelet<S>

Type Parameters:

S - the Scopelet subtype extending this class

All Implemented Interfaces:

AutoCloseable, Constable, Aggregate, Factory<S>

Direct Known Subclasses:

MapBackedScopelet, NoneScopelet

public abstract class Scopelet<S extends Scopelet<S>>
extends Object
implements AutoCloseable, Factory<S>

A manager of object lifespans on behalf of one or more notional scopes.

Author:

Laird Nelson

See Also:

• instance(Object, Factory, Creation)

Field Summary

Fields

Modifier and Type	Field	Description
static final Attributes	APPLICATION_ID	An Attributes identifying the (well-known and normal) application scope.
static final Attributes	NONE_ID	An Attributes identifying the (well-known) none pseudo-scope.
static final Attributes	SCOPE	An Attributes identifying the scope designator.
static final Attributes	SINGLETON_ID	An Attributes identifying the (well-known) singleton pseudo-scope.

Fields inherited from interface org.microbean.bean.Aggregate

EMPTY_ASSIGNMENTS, EMPTY_DEPENDENCIES

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Scopelet()	Creates a new Scopelet.

Method Summary

Modifier and Type	Method	Description
boolean	active()	Returns true if and only if this Scopelet is active at the moment of the call.
void	close()	Irrevocably closes this Scopelet, and, by doing so, notionally makes it irrevocably closed and inactive.
protected final boolean	closed()	Returns true if and only if at the moment of invocation this Scopelet is (irrevocably) closed (and therefore also not active).
final S	create(Creation<S> r)	Creates this Scopelet by simply returning it.
final boolean	destroys()	Returns true when invoked to indicate that Scopelet implementations destroy what they create.
abstract <I> I	instance(Object id, Factory<I> factory, Creation<I> creation)	Checks to see if this Scopelet is active and then returns a pre-existing or created-on-demand contextual instance suitable for the combination of identifier, Factory and Creation, or null
boolean	remove(Object id)	Checks to see if this Scopelet is active and then removes any contextual instance stored under the supplied id, returning true if and only if removal actually took place.
final S	singleton()	Returns this Scopelet if it has been created via the create(Creation) method, or null if that method has not yet been invoked.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.microbean.bean.Aggregate

assign, dependencies

Methods inherited from interface org.microbean.bean.Factory

describeConstable, destroy

Field Details

SCOPE

public static final Attributes SCOPE

An Attributes identifying the scope designator.

SINGLETON_ID

public static final Attributes SINGLETON_ID

An Attributes identifying the (well-known) singleton pseudo-scope.

The Attributes constituting the singleton pseudo-scope identifier is attributed with the scope designator, the qualifier designator, and the primordial qualifier, indicating that the scope it identifies governs itself.

APPLICATION_ID

public static final Attributes APPLICATION_ID

An Attributes identifying the (well-known and normal) application scope.

NONE_ID

public static final Attributes NONE_ID

An Attributes identifying the (well-known) none pseudo-scope.

Constructor Details

Scopelet

protected Scopelet()

Creates a new Scopelet.

Method Details

create

public final S create(Creation<S> r)

Creates this Scopelet by simply returning it.

Specified by:

create in interface Factory<S extends Scopelet<S>>

Returns:

this Scopelet

singleton

public final S singleton()

Returns this Scopelet if it has been created via the create(Creation) method, or null if that method has not yet been invoked.

Specified by:

singleton in interface Factory<S extends Scopelet<S>>

Returns:

this Scopelet if it has been "created"; null otherwise

See Also:

• create(Creation)

destroys

public final boolean destroys()

Returns true when invoked to indicate that Scopelet implementations destroy what they create.

Specified by:

destroys in interface Factory<S extends Scopelet<S>>

Returns:

true when invoked

See Also:

• Factory.destroy(Object, org.microbean.bean.Destruction)
• create(Creation)

active

public boolean active()

Returns true if and only if this Scopelet is active at the moment of the call.

Overrides of this method must ensure that if closed() returns true, this method must return false.

Returns:

true if and only if this Scopelet is active at the moment of the call

See Also:

• closed()

instance

public abstract <I> I instance(Object id,
 Factory<I> factory,
 Creation<I> creation)

Checks to see if this Scopelet is active and then returns a pre-existing or created-on-demand contextual instance suitable for the combination of identifier, Factory and Creation, or null

Type Parameters:

I - the type of contextual instance

Parameters:

id - an identifier that can identify a contextual instance; may be null

factory - a Factory; may be null

creation - a Creation, typically the one in effect that is causing this method to be invoked in the first place; may be null

Returns:

a contextual instance, possibly pre-existing, or possibly created just in time, or null

Throws:

InactiveScopeletException - if this Scopelet is not active

ClassCastException - if creation is non-null and does not implement Destruction, a requirement of its contract

See Also:

• Creation

remove

public boolean remove(Object id)

Checks to see if this Scopelet is active and then removes any contextual instance stored under the supplied id, returning true if and only if removal actually took place.

The default implementation of this method always returns false. Subclasses are encouraged to override it as appropriate.

Parameters:

id - an identifier; may be null

Returns:

true if and only if removal actually occurred

Throws:

InactiveScopeletException - if this Scopelet is not active

close

public void close()

Irrevocably closes this Scopelet, and, by doing so, notionally makes it irrevocably closed and inactive.

Overrides of this method must call super.close() as part of their implementation or undefined behavior may result.

Specified by:

close in interface AutoCloseable

See Also:

• closed()
• active()

closed

protected final boolean closed()

Returns true if and only if at the moment of invocation this Scopelet is (irrevocably) closed (and therefore also not active).

Returns:

true if and only if at the moment of invocation this Scopelet is (irrevocably) closed (and therefore also not active)

See Also:

• active()