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https://issues.apache.org/jira/browse/ISIS-1897?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Dan Haywood closed ISIS-1897.
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> applib: the new ObjectContracts needs backward compatibility
> ------------------------------------------------------------
>
> Key: ISIS-1897
> URL: https://issues.apache.org/jira/browse/ISIS-1897
> Project: Isis
> Issue Type: Improvement
> Components: Core
> Reporter: Andi Huber
> Assignee: Andi Huber
> Priority: Major
> Fix For: 2.0.0-M1
>
>
> ObjectContracts seems to be heavily used with the incode platform.
> To ease migration, I've provided functional backward compatibility.
> However the old methods are now marked for deprecation!
>
>
> ----
> Isis until 1.16. uses reflection on every of these 4 calls ...
> {code:java}
> public class ApplicationPermission implements
> Comparable<ApplicationPermission> {
> ...
> private final static String propertyNames = "role, featureType,
> featureFqn, mode";
> @Override
> public int compareTo(final ApplicationPermission other) {
> return ObjectContracts.compare(this, other, propertyNames);
> }
> @Override
> public boolean equals(final Object obj) {
> return ObjectContracts.equals(this, obj, propertyNames);
> }
> @Override
> public int hashCode() {
> return ObjectContracts.hashCode(this, propertyNames);
> }
> @Override
> public String toString() {
> return ObjectContracts.toString(this, propertyNames);
> }
>
> ...
>
> }
> {code}
> ----
> Isis since 2.0.0 provides an optimized variant now: reflection is used only
> once at class initialization ...
> {code:java}
> public class ApplicationPermission implements
> Comparable<ApplicationPermission> {
> ...
> private final static String propertyNames = "role, featureType,
> featureFqn, mode";
>
> private final static ObjectContract<ApplicationPermission> contract
> = ObjectContracts.parse(ApplicationPermission.class, propertyNames);
> @Override
> public int compareTo(final ApplicationPermission other) {
> return contract.compare(this, other);
> }
> @Override
> public boolean equals(final Object other) {
> return contract.equals(this, other);
> }
> @Override
> public int hashCode() {
> return contract.hashCode(this);
> }
> @Override
> public String toString() {
> return contract.toString(this);
> }
>
> ...
>
> }
> {code}
> ----
> However the *recommended* way to use 'object contracts' now is to no longer
> resort to reflection.
> Parsing as shown above can be replaced by static method handles to enforce
> that properties actually exist (at compile-time)
> {code:java}
> private final static ObjectContract<ApplicationPermission> contract =
> ObjectContracts.contract(ApplicationPermission.class)
> .thenUse("role", ApplicationPermission::getRole)
> .thenUse("featureType", ApplicationPermission::getFeatureType)
> .thenUse("featureFqn", ApplicationPermission::getFeatureFqn)
> .thenUse("mode", ApplicationPermission::getMode);
> {code}
> If different then natural order comparators are needed then resort to Java's
> Comparator composition ...
> {code:java}
> private final static ObjectContract<ApplicationPermission> contract =
> ObjectContracts.contract(ApplicationPermission.class)
> .thenUse("role", ApplicationPermission::getRole,
> Comparator.naturalOrder())
> .thenUse("featureType", ApplicationPermission::getFeatureType,
> Comparator.reverseOrder())
> .thenUse("featureFqn", ApplicationPermission::getFeatureFqn,
> Comparator.nullsFirst(Comparator.naturalOrder()))
> .thenUse("mode", ApplicationPermission::getMode,
> Comparator.nullsLast(Comparator.naturalOrder()));
> {code}
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