How to call operator<< on "this" in a descendant of std::stringstream?
class mystream : public std::stringstream
{
public:
void write_something()
{
this << "something";
}
};
This results in the following two compile errors on VC++10:
error C2297: '<<' : illegal, right operand has type 'const char [10]'
error C2296: '<<' : illegal, left operand has type 'mystream *const '
Judging from the second one, thi开发者_运维知识库s is because what this
points at can't be changed, but the << operator does (or at least is declared as if it does). Correct?
Is there some other way I can still use the <<
and >>
operators on this
?
mystream *const
means that this
is a constant pointer to a non-constant object. The problem is that you're trying to stream-insert into a pointer -- you must insert into a stream. Try the following.
*this << "something";
The destructor of an stringstream (actually a basic_stringstream<char>
) is not virtual, and as all classes from the C++ SL, you're not really supposed to derive from them...
Depending on what exactly you want to do, I will tell you to prefer composition to inheritance, and maybe create your own templated << and >> operators that will use your underlying stream. Or maybe it is wiser not to use a stringstream as a member.
精彩评论