CODEWITHSUNDEEP
c++
wanghui
wanghui

Reputation: 11

What does Return<void> mean?

I saw a program in android source code ,it's about the return value in c++,please look the following ,Thanks!

Return<void> RadioResponse_v1_1::getIccCardStatusResponse(const RadioResponseInfo& info,
                                         const CardStatus& card_status) {
       rspInfo = info
       cardStatus = card_statu parent_v1_1.notify(info.serial30);
       return void();
}

My question is that the Return represent what?I've never seen this program before. Best Regards

Upvotes: 0

Views: 1097

Answers (1)

parktomatomi
parktomatomi

Reputation: 4079

It's hard to dig through all the layers of code generation of the android source code, but here is some documentation about it: https://source.android.com/devices/architecture/hidl-cpp/functions

It gets used in code generated from some hardware abstraction layer interface language used by AOSP. From the documentation:

Return objects store transport error indications as well as a T value (except Return).

...

Return objects have implicit conversion to and from their T value

So, in this case Return<T> is a container that can store a value or an error. This function doesn't return anything when it's successful, so it returns Result<void>. In functional programming languages, this is sometimes called an either: https://www.ibm.com/developerworks/library/j-ft13/index.html

EDIT: aha, here it is: https://android.googlesource.com/platform/system/libhidl/+/refs/heads/master/base/include/hidl/Status.h

Upvotes: 1

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