js8544 opened a new pull request, #15293:
URL: https://github.com/apache/arrow/pull/15293
# Which issue does this PR close?
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If this is not a [minor
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Then could you also rename the pull request title in the following format?
GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}
or
MINOR: [${COMPONENT}] ${SUMMARY}
In the case of old issues on JIRA the title also supports:
ARROW-${JIRA_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}
PARQUET-${JIRA_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}
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Closes #15292
# Rationale for this change
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All array classes have the `using TypeClass = xxx` type alias except for
ExtensionArray.
With the alias, it will be easier to write templated inline visitors such as
the following code block:
```Cpp
class ExampleVisitor {
public:
template <typename T>
Status Visit(const T& arr) {
if constexpr (arrow::is_number_type<typename T::TypeClass>::value) {
///
} else {
///
}
return Status::OK();
}
};
```
Current it fails to compile with message: `No type named 'TypeClass' in
'arrow::ExtensionArray'`.
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