Module org.scijava.discovery

Package org.scijava.discovery

Interface Discoverer

All Known Implementing Classes:

ManualDiscoverer

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface Discoverer

Discovers implementations of a given type.

Author:

Gabriel Selzer

Method Summary

Modifier and Type	Method	Description
static <T> List<Discoverer>	all(Function<Class<T>,? extends Iterable<T>> func)	Gets all Discoverers made available through Iterable, as well as a Discoverer that is itself backed by the Iterable.
<U> List<U>	discover(Class<U> c)	Discovers implementations of some Class c.
default <U extends Comparable<U>> Optional<U>	discoverMax(Class<U> c)	Finds the maximum implementation of any Comparable c.
default <U extends Comparable<U>> Optional<U>	discoverMin(Class<U> c)	Finds the minimum implementation of any Comparable c.
default Discoverer	except(Class<?>... classes)	Wraps up this Discoverer into a Discoverer that only discoverers classes classes
default Discoverer	onlyFor(Class<?>... classes)	Wraps up this Discoverer into a Discoverer that only discoverers classes classes
static Discoverer	union(Iterable<Discoverer> discoverers)	Accumulates multiple Discoverers into one mega-Discoverer
static <T> Discoverer	using(Function<Class<T>,? extends Iterable<T>> func)	Creates a Discoverer operating via Function.

Method Detail

discover

<U> List<U> discover(Class<U> c)

Discovers implementations of some Class c.

Type Parameters:

U - the Type of the Class being searched for

Parameters:

c - the Class being searched for

Returns:

a List of implementations of c

using

static <T> Discoverer using(Function<Class<T>,? extends Iterable<T>> func)

Creates a Discoverer operating via Function.

NB: The Function input is extremely important for e.g. JPMS compatibility. This puts the code loading the services into the user's module, allowing access to all of the services exposed to (and used by) the calling module. Otherwise, all service interfaces would have to be used by this module, which is not extensible.

Type Parameters:

T - the Class we attempt to discover, and consequently the supertype of all implementations contained in the Iterable

Parameters:

func - the Function generating a Iterable of implementations provided a Class

Returns:

A Discoverer backed by func

all

static <T> List<Discoverer> all(Function<Class<T>,? extends Iterable<T>> func)

Gets all Discoverers made available through Iterable, as well as a Discoverer that is itself backed by the Iterable.

It is highly recommended to call this method using List<Discoverer> discoverers = Discoverers.all(ServiceLoader::load);

Type Parameters:

T - the Class we attempt to discover, and consequently the supertype of all implementations contained in the Iterable

Parameters:

func - the Function generating a Iterable of implementations provided a Class. Notably, this callback has the module scope of the caller, which is useful for circumnavigating module permissions when using e.g. JPMS. If we instead used ServiceLoader.load(Class) directly, we'd only be able to discover implementations whose interface was used by module org.scijava.discovery.

It is in the user's best interest to make this Function as general as possible.

Returns:

A List of Discoverers, including a Discoverer backed by func, and all Discoverers found by func

union

static Discoverer union(Iterable<Discoverer> discoverers)

Accumulates multiple Discoverers into one mega-Discoverer

Parameters:

discoverers - the Discoverers to be wrapped

Returns:

the mega-Discoverer

onlyFor

default Discoverer onlyFor(Class<?>... classes)

Wraps up this Discoverer into a Discoverer that only discoverers classes classes

Parameters:

classes - the Classes

Returns:

the wrapping

except

default Discoverer except(Class<?>... classes)

Wraps up this Discoverer into a Discoverer that only discoverers classes classes

Parameters:

classes - the Classes

Returns:

the wrapping

discoverMax

default <U extends Comparable<U>> Optional<U> discoverMax(Class<U> c)

Finds the maximum implementation of any Comparable c.

Type Parameters:

U - the Type of c

Parameters:

c - the Class, extending Comparable that the returned implementation must implement

Returns:

the maximum implementation of c

discoverMin

default <U extends Comparable<U>> Optional<U> discoverMin(Class<U> c)

Finds the minimum implementation of any Comparable c.

Type Parameters:

U - the Type of c

Parameters:

c - the Class, extending Comparable that the returned implementation must implement

Returns:

the minimum implementation of c