I wanted to write a function with a variable argument list. I want to explore my options. I'm pretty sure I came accross a boost template class that was designed for this purpose, but I can't think of the name of it? Can anyone tell me? or did I dream this up! Thanks
If you only need to accept a variable count of arguments of the same type, taking a container would be the common thing to do. Creation of the container however can be eased using Boost.Assign:
void f(const std::vector<int>& vec) {}
f(boost::assign::list_of(1)(2)(3)(4));
Alternatively you can go for operator overloading (e.g. of operator()
or operator<<
) yourself, similar to the approach taken by the standard library streams:
op() << arg1 << arg2 << arg3;
If you really want to provide a type-safe variadic function (without using C++0x features), Boost.Preprocessor can help. A generic example:
#define OUT(z, n, name) << name ## n
#define MAKE_FUNC(z, n, unused) \
template<class T BOOST_PP_ENUM_TRAILING_PARAMS(n, class T)> \
void func(T t BOOST_PP_ENUM_TRAILING_BINARY_PARAMS(n, T, t) ) { \
std::cout << t BOOST_PP_REPEAT(n, OUT, t) << std::endl; \
}
BOOST_PP_REPEAT(9, MAKE_FUNC, ~) // generates func() versions taking 1-10 arguments
func(1, "ab", 'c'); // prints "1abc"
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