ru.vyarus.dropwizard.guice.module.context.unique

Interface DuplicateConfigDetector

All Known Implementing Classes:

LegacyModeDuplicatesDetector

public interface DuplicateConfigDetector

Configuration items may be registered by class (extension, installer) or by instance (guicey bundle, guice module). Duplicates are obvious for class registrations: one class - one extension instance (no matter how much times this class was registered). But for instances it's not so obvious. For example, in dropwizard you can register multiple instances of the same bundle (and it's often very useful!). But, sometimes, there are common bundles (or guice modules), used by multiple other bundles (and so declared by all of them). In this case it would be desirable to register common bundle just once (and avoid duplicate).

Default deduplication logic for instances will consider equal objects as duplicate. In cases, when it is impossible to properly implement equals method (e.g. 3rd party class), custom deduplication detector could be implemented.

Since:

03.07.2019

See Also:

with legacy guicey behaviour implementation (always one instance per class)

Method Summary

Modifier and Type	Method and Description
java.lang.Object	getDuplicateItem(java.util.List<java.lang.Object> registered, java.lang.Object newItem) Called every time when configured object (guicey bundle or guice module) of the same type is already registered.

Method Detail

getDuplicateItem

java.lang.Object getDuplicateItem(java.util.List<java.lang.Object> registered,
                                  java.lang.Object newItem)

Called every time when configured object (guicey bundle or guice module) of the same type is already registered. Note that method is called only if new instance is not equal to any registered instances of the same type. Method must return duplicate object from already registered.

For example, if 3 or more instances of the same type are registered then method would be called for each new configured instance (in case of 3 registrations - 2 method calls, assuming that instances are not equal).

Parameters:

registered - already registered items

newItem - new item to check

Returns:

duplicate object from already registered (to mark this one as duplicate to already registered)