CODEWITHSUNDEEP
c++shared-librarieshourglass
Zarian
Zarian

Reputation: 41

How to pass vector<T> between library/module boundary using hourglass pattern?

The question is related to a talk by Stefanus Du Toit on hourglass pattern. Its a great talk, really helpful for library writers.

Youtube Link: https://youtu.be/PVYdHDm0q6Y

Slideshare Link: http://www.slideshare.net/StefanusDuToit/cpp-con-2014-hourglass-interfaces-for-c-apis

Ok here is the question:

Say I have to pass a std::vector<MyObject> across the library boundary. What is the best way to do this using hourglass pattern. I am concerned about the performance as well as keeping a clean interface. Given below is a set of example interfaces that I want to implement.

Clientside C++ interface:

void MyLibraryClass::DoSomething(const std::vector<MyObject>& objs);

C Interface:

???? (Not sure what is the best practice here)

Internall library C++ interface:

MyInternalLibraryClass::DoSomething(const std::vector<MyObjectImpl>& objs);

Hope this explains my question.

Upvotes: 4

Views: 336

Answers (1)

TheROE
TheROE

Reputation: 134

Best would to pass an array internally:

void do_something(MyObject* array, size_t count);

The internal class use something like std::span in its interface, since you are not modifying the vector, it would be more flexible and shouldn't require that much code changes.

Upvotes: 0

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