GH-15292: [C++] Typeclass alias is missing in ExtensionArray #15293
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Which issue does this PR close?
Closes #15292
Rationale for this change
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:
Current it fails to compile with message:
No type named 'TypeClass' in 'arrow::ExtensionArray'
.