Trim a string with C++ [2]

I've wrote a blog to discuss how to trim a string in C++. Now I find an other way in high performance, see the implements below: 

#include <string>
#define  STRING_TRIM_DROPS    " \t"

std::string& trim(std::string &s)
{
    static std::string drops = STRING_TRIM_DROPS;  // A char list specifies which characters should be trimmed.

    if (s.empty())
    {
        return s;
    }

    s.erase(0, s.find_first_not_of(drops));
    s.erase(s.find_last_not_of(drops) + 1);
    return s;
}

Yes, using string::erase() method is the fastest way I ever met.