AMDG Ovanes Markarian wrote:
Hello *,
I have some pre-processor sequence in form of:
(X1) (X2) (X3) (X4)
which is expanded by BOOST_PP_SEQ_FOR_EACH to template parameters:
some_template<X1, X2, X3, X4> ...
My problem now is that some of Xn parameters can be a template instantiation and that actually causes PP to think, that there are more parameters to the function applied by ..._SEQ_FOR_EACH. Example: some_other_template<T1, T2> cause preprocessor to think that there are 2 params some_other_template<T1 and T2>.
Putting the parameter into additional braces like ((X4)) results in the template:
some_template<X1, X2, X3, (X4)> and that results in a compiler error. I know this construct can switch off ADL, but I don't know why it result here in a compiler error, since I fully qualify the X4 (from which namespace it is). Is there any way to treat Xn as a single paramer but during the final pre-processing stage get rid of additional braces?
There are a couple of ways to do it. You can make each element of the Seq to be itself a seq and then call BOOST_PP_SEQ_ENUM on the inside: ((X1)) ((X2)) ((some_other_template<T1)(T2>)) Another way is to use template metaprogramming (X1)(X2)(parenthesize_type(wrap<some_other_template<T1, T2>>)) template<class T> struct unparenthesize { typedef T type; }; template<class T> struct unparenthesize<parenthesized_type(wrap<T>)> { typedef T type; }; In Christ, Steven Watanabe