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attached my code to show my problem. It seems to work (partially) so far, but not the vector<int> where I get a compile error. This is my first try with SFINAE in that way. Are the conditions correct and robust enough? How to compile it? Did I forgot one use case? Using this small helper would simplify some post processing.

What visit() overload did you intend to call for vector<int>? Note that enable_if condition: mpl::and_< boost::has_range_const_iterator<VisitableT>, boost::is_void<typename VisitorT::result_type> >,

seems to be fulfilled for vector<int> case, doesn't it? But it's obviously not the right overload, as int is not variant.

thank you, you did point out it; unfortunately, my extension doesn't compile. Thanks, Olaf

Am 26.05.2013 15:20, schrieb Igor R:

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What visit() overload did you intend to call for vector<int>? Note that enable_if condition: mpl::and_< boost::has_range_const_iterator<VisitableT>, boost::is_void<typename VisitorT::result_type> >,

seems to be fulfilled for vector<int> case, doesn't it? But it's obviously not the right overload, as int is not variant.

thank you, you did point out it; unfortunately, my extension doesn't compile.

Because you actually should apply is_variant metafunction to the value_type of the container, not to the container itself: mpl::not_, <....> is_variant<typename VisitableT::value_type>,

Now, I've got it; thanks a lot Igor!