On Aug 3, 3:29 pm, Stuart Golodetz
<sgolod...@NdOiSaPlA.pMiPpLeExA.ScEom> wrote:
Just wondering if anyone can see a problem with the code below? The
intent is to allow you to construct strings "on-the-fly" via streaming,
e.g. f(OSSWrapper() << "Wibble " << 42). The code works, but I'm
concerned that it might not be the best practice in the world -
particularly the need to use a const reference to bind to the temporary,
and the ensuing need to make m_os mutable. Seems a bit icky to me! Is
there a better way?
Cheers,
Stu
#include <iostream>
#include <sstream>
#include <string>
class OSSWrapper
{
private:
mutable std::ostringstream m_os;
public:
operator std::string() const
{
return m_os.str();
}
template <typename T>
friend const OSSWrapper& operator<<(const OSSWrapper& ossw, const T& rhs)
{
ossw.m_os << rhs;
return ossw;
}
};
int main()
{
std::string s = OSSWrapper() << "Blah " << 23 << ' ' << 9.0;
std::cout << s << std::endl;
return 0;
}
Hi Stuart - and hi everybody, as this is my very first post here.
I'm no C++ expert, so I can only give my two cents.
The code you posted didn't compile on my machine (WinXP and
Code::Blocks 8.02) - it returned some kind of error telling
std::ios_base is private and cannot be accessed.
Converting the friend function to a normal const member function did
actually let it compile without any warning/error, and the program ran
as expected - and honestly I can see no reason for setting a member
function as a friend of its own class, but recall that I'm an
hobbyist.
I would post my code but I'm new here and I don't want to make the
mistake of doing others' work in their place, right here in my first
post. Please excuse me if I'm wrong.
As for my knowledge and my experience, after fixing that function
there would be no problem with your class - apart that the template
definition will have to be included in every compile unit it is used,
unless your compiler lets you use the export keyword.
Another issue I've met making a similar class is with std::endl, which
cannot be passed to your operator<<() function. About this, in my
code, I use to create a local "endl" constant setting it to a newline
character, just for my very ease - recall I'm an DIY-coder, again - I
know that some similar classes can be implemented allowing standard
manipulators, but that's just out of the scope of my skills, and maybe
also out of the scope of the original questions.
Have good coding, hope this helped you.
Cheers,
Francesco