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https://issues.apache.org/jira/browse/GROOVY-12031?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18082972#comment-18082972
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ASF GitHub Bot commented on GROOVY-12031:
-----------------------------------------
Copilot commented on code in PR #2553:
URL: https://github.com/apache/groovy/pull/2553#discussion_r3291070512
##########
src/main/java/org/codehaus/groovy/runtime/DefaultGroovyMethods.java:
##########
@@ -15068,6 +15068,33 @@ public void remove() {
}
}
+
//--------------------------------------------------------------------------
+ // takeIf
+
+ /**
+ * Returns this object if it satisfies the given predicate, or {@code null}
+ * otherwise. Useful for guarding a value through a chain, particularly
with
+ * the Elvis or safe-navigation operators.
+ * <pre class="language-groovy groovyTestCase">
+ * assert 'hello'.takeIf{ it.startsWith('h') } == 'hello'
+ * assert 'hello'.takeIf{ it.startsWith('z') } == null
+ * assert ('input'.takeIf{ it.startsWith('http') } ?: "https://input";) ==
'https://input'
+ * assert [1, 2, 3].takeIf{ !it.isEmpty() }?.size() == 3
+ * assert [].takeIf{ !it.isEmpty() }?.size() == null
+ * </pre>
+ * The predicate is invoked with the receiver as its argument; the receiver
+ * is not used as a delegate. The receiver is passed through to the
predicate
+ * unchanged, including when it is {@code null}.
+ *
+ * @param self the object to test
+ * @param condition the predicate applied to {@code self}
+ * @return {@code self} if {@code condition.test(self)} is {@code true},
otherwise {@code null}
+ * @since 6.0.0
+ */
+ public static <T> T takeIf(T self, Predicate<T> condition) {
+ return condition.test(self) ? self : null;
Review Comment:
The parameter type `Predicate<T>` is unnecessarily invariant for a
general-purpose GDK method. Using `Predicate<? super T>` makes the API more
flexible (e.g., allows a `Predicate<Object>` to be used when `T` is a subtype)
without changing behavior.
> Provide a DGM#takeIf method
> ---------------------------
>
> Key: GROOVY-12031
> URL: https://issues.apache.org/jira/browse/GROOVY-12031
> Project: Groovy
> Issue Type: New Feature
> Reporter: Paul King
> Assignee: Paul King
> Priority: Major
>
> Matching Kotlin's method of the same name.
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