bkietz commented on a change in pull request #9547:
URL: https://github.com/apache/arrow/pull/9547#discussion_r580503186
##########
File path: cpp/src/arrow/util/future.h
##########
@@ -493,6 +493,22 @@ class ARROW_MUST_USE_TYPE Future {
});
}
+ /// \brief Implicit constructor to create a future from a Result, enabling
use
+ /// of macros like ARROW_ASSIGN_OR_RAISE.
+ Future(Result<ValueType> res) : Future() { // NOLINT(runtime/explicit)
+ if (ARROW_PREDICT_TRUE(res.ok())) {
+ impl_ = FutureImpl::MakeFinished(FutureState::SUCCESS);
+ } else {
+ impl_ = FutureImpl::MakeFinished(FutureState::FAILURE);
+ }
+ SetResult(std::move(res));
+ }
+
+ /// \brief Implicit constructor to create a future from a Status, enabling
use
+ /// of macros like ARROW_RETURN_NOT_OK.
+ Future(Status s) // NOLINT(runtime/explicit)
Review comment:
```suggestion
Future(Status s) // NOLINT runtime/explicit
```
##########
File path: cpp/src/arrow/util/future.h
##########
@@ -493,6 +493,22 @@ class ARROW_MUST_USE_TYPE Future {
});
}
+ /// \brief Implicit constructor to create a future from a Result, enabling
use
+ /// of macros like ARROW_ASSIGN_OR_RAISE.
+ Future(Result<ValueType> res) : Future() { // NOLINT(runtime/explicit)
Review comment:
Some tools don't recognize the parenthesized form
```suggestion
Future(Result<ValueType> res) : Future() { // NOLINT runtime/explicit
```
##########
File path: cpp/src/arrow/util/future_test.cc
##########
@@ -392,6 +392,30 @@ TEST(FutureSyncTest, GetStatusFuture) {
}
}
+// Ensure the implicit convenience constructors behave as desired.
+TEST(FutureSyncTest, ImplicitConstructors) {
+ {
+ auto fut = ([]() -> Future<MoveOnlyDataType> {
+ return arrow::Status::Invalid("Invalid");
+ })();
+ AssertFailed(fut);
+ ASSERT_RAISES(Invalid, fut.result());
+ }
+ {
+ auto fut = ([]() -> Future<MoveOnlyDataType> {
+ return
arrow::Result<MoveOnlyDataType>(arrow::Status::Invalid("Invalid"));
+ })();
+ AssertFailed(fut);
+ ASSERT_RAISES(Invalid, fut.result());
+ }
Review comment:
Test case for the previous:
```suggestion
}
{
auto fut = ([]() -> Future<MoveOnlyDataType> { return
MoveOnlyDataType(42); })();
AssertSuccessful(fut);
}
```
##########
File path: cpp/src/arrow/util/future.h
##########
@@ -493,6 +493,22 @@ class ARROW_MUST_USE_TYPE Future {
});
}
Review comment:
For completeness, we could also support construction from ValueType:
```suggestion
}
/// \brief Implicit constructor to create a finished future from a value
Future(ValueType val) : Future() { // NOLINT runtime/explicit
impl_ = FutureImpl::MakeFinished(FutureState::SUCCESS);
SetResult(std::move(val));
}
```
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