bkietz commented on a change in pull request #7318:
URL: https://github.com/apache/arrow/pull/7318#discussion_r434162682
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File path: cpp/src/arrow/compute/function.h
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@@ -229,5 +233,22 @@ class ARROW_EXPORT ScalarAggregateFunction
const std::vector<ValueDescr>& values) const;
};
+/// \brief A function that dispatches to other functions. Must override
+/// Function::Execute.
+///
+/// For Array, ChunkedArray, and Scalar Datum kinds, may rely on the execution
+/// of concrete Function types, but must handle other Datum kinds on its own.
+class ARROW_EXPORT MetaFunction : public Function {
+ public:
+ int num_kernels() const override { return 0; }
+
+ Result<Datum> Execute(const std::vector<Datum>& args, const FunctionOptions*
options,
+ ExecContext* ctx) const override;
+
+ protected:
Review comment:
Instead of refusing the bequest by default, I think it'd be better to
provide a pure virtual function for MetaFunction subclasses to override:
```suggestion
Result<Datum> Execute(const std::vector<Datum>& args, const
FunctionOptions* options,
ExecContext* ctx) const override {
return ExecuteImpl(args, options, ctx);
}
protected:
virtual Result<Datum> ExecuteImpl(const std::vector<Datum>& args, const
FunctionOptions* options,
ExecContext* ctx) const = 0;
```
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