Re: [Boost-users] Can't compile very simple snippet that uses boost::tuple

From: Stuart Dootson (stuart.dootson_at_[hidden])
Date: 2004-11-28 06:36:34

On Sat, 27 Nov 2004 19:25:20 -0800, Frank Astier <fastier_at_[hidden]> wrote:
> I am pretty sure it's because of my lack of skills with templates...
> Still, I don't understand why I can stream a vector if it's on its own,
> but not if it's stored in a boost::tuple. And it works with a std::pair!
> Any hint?
> 
> 
> int main(int, char**)
> {
>         vector<float> v;
>         cout << v;       // Works fine
> 
>         pair<vector<float>, pair<int, int> > p;
>         cout << p;       // Works fine
> 
>         tuple<vector<float> > t;
>         cout << t;       // <== WON'T COMPILE
> }
> 
> Thanks,
> 
> Frank

I suspect it's because you need to define the operator<< for vector in
the same namespace as vector (i.e. std) for the tuples operator<< to
be able to find it. It's called 'argument dependent lookup'.

Stuart Dootson