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https://issues.apache.org/jira/browse/PARQUET-1321?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16507857#comment-16507857
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ASF GitHub Bot commented on PARQUET-1321:
-----------------------------------------
gszadovszky commented on a change in pull request #493: PARQUET-1321:
LogicalTypeAnnotation.LogicalTypeAnnotationVisitor#visit methods should have a
return value
URL: https://github.com/apache/parquet-mr/pull/493#discussion_r194342297
##########
File path:
parquet-column/src/main/java/org/apache/parquet/schema/LogicalTypeAnnotation.java
##########
@@ -834,45 +838,63 @@ public int hashCode() {
* The default implementation for each logical type specific visitor method
is empty.
* <p>
* Example usage: logicalTypeAnnotation.accept(new
LogicalTypeAnnotationVisitor() { ... });
+ *
+ * Every visit method returns {@link Optional#empty()} by default.
+ * It means that for the given logical type no specific action is needed.
+ * Client code can use {@link Optional#orElse(Object)} to return a default
value for unhandled types,
+ * or {@link Optional#orElseThrow(Supplier)} to throw exception if omitting
a type is not allowed.
*/
- public interface LogicalTypeAnnotationVisitor {
- default void visit(StringLogicalTypeAnnotation logicalTypeAnnotation) {
+ public interface LogicalTypeAnnotationVisitor<T> {
Review comment:
Thanks for adding the comments. I accept the concept of using Optionals here.
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> LogicalTypeAnnotation.LogicalTypeAnnotationVisitor#visit methods should have
> a return value
> -------------------------------------------------------------------------------------------
>
> Key: PARQUET-1321
> URL: https://issues.apache.org/jira/browse/PARQUET-1321
> Project: Parquet
> Issue Type: Improvement
> Components: parquet-mr
> Reporter: Nandor Kollar
> Assignee: Nandor Kollar
> Priority: Major
>
> LogicalTypeAnnotationVisitor inside LogicalTypeAnnotation is intended to be
> used by clients who would like to execute custom code which depends on the
> type of the logical type annotation. However, it is difficult to give back
> any result from the visitor, since both LogicalTypeAnnotation#accept, and
> LogicalTypeAnnotationVisitor has void return type.
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