C++, to return a various class instance how to create a template?

Question

I'm trying to make a function that returns "vector"

vector<Class A,B or C> _Class123::getVectorList();

or vector<struct A,B or c> _class123::getDataList();

Various classes are three classes that I define. depending on the logic, this function should return one of those.

in C++, is it possible with template?

You shouldn't use [reserved names](http://stackoverflow.com/questions/228783) for your types. — Mike Seymour, Nov 17 '13 at 16:02

score 3 · Answer 1 · answered Nov 17 '13 at 15:45

3

You sound like you want a discriminated union, in which case you might want to look into something like Boost.Variant:

Your function would then be:

std::vector<boost::variant<A,B,C> > _Class123::getVectorList();

answered Nov 17 '13 at 15:45

Stuart Golodetz

Just for curiosity: Is there a [tag:c++11] standard solution for this problem? – πάντα ῥεῖ Nov 17 '13 at 15:49
Thank you, but I couldn't use other lib. Is there any other way without ext.lib? – dipt Nov 17 '13 at 15:50
3

@user1060039: The other way is to write your own discriminated union. There's no standard type for that. But there's no sensible reason not to use this Boost library; it's header-only, with an unrestrictive license. – Mike Seymour Nov 17 '13 at 15:58
1

If you're not allowed to use boost', simply implement the variant data type yourself, this has gotten a lot easier in C++11 due to the relaxation of union. – Skeen Nov 17 '13 at 16:03
@g-makulik: No, there's no equivalent of Boost.Variant in the C++ Standard Library unfortunately (yet, at least). – Stuart Golodetz Nov 17 '13 at 16:16

1 Answers1