drop in replacement for stringstream that compiles to nothing

[jabbah]

hi

I find myself using stringstream all over my code just to build debug messages that I may or may not write to cout later. that is very comfortable while developing but is generally useless for productive code.

so I would like to have some construct that the compiler will remove in the case of NDEBUG. but I dont want to write #ifndef NDEBUG everywhere.

I have tried with this, but seemingly the compiler still cant completely remove NullStream because if I raise the loopcount to something like 10e7 it takes 3 seconds (with MSVS 2005 /O2, even longer with cygwin/gcc344 or ubuntu7.1/gcc413 -O3)

[code=c]
#include <iostream>
#include <string>
#include <sstream>
using namespace std;


class NullStream
{
public:
inline const NullStream& operator<< ( const string & s ) const
{
return *this;
}
inline const NullStream& operator<< ( int& i ) const
{
return *this;
}
inline const NullStream& operator<< ( unsigned int& i ) const
{
return *this;
}
};
inline ostream& operator<<( ostream& o, const NullStream& n)
{
return o;
}
inline ostream& operator<<( ostream& o, const stringstream& s )
{
o << s.str();
return o;
}
#ifdef NDEBUG
typedef NullStream LogStream;
#else
typedef ostringstream LogStream;
#endif




void main_logstream( )
{
cout << __FUNCTION__ << "\n";
LogStream buf;

double clock_begin = clock();

for ( unsigned int i = 0 ; i < 10e7 ; i++ )
{
buf << i << " ";
}
cout << "buffer: " << buf << "\n";
cout << "time: " << ( ( clock() - clock_begin ) / CLOCKS_PER_SEC ) << " s\n";
}
[/code]


I had expected that the compiler should be able to see that the body of that loop only consistst of a couple of calls to functions with empty bodies and thus the whole loop can be removed.

Anybody any suggestions?

[jabbah]

uups, seemingly the compiler wont even remove

[code=c]
for ( unsigned int i = 0 ; i < 10e7 ; i++ )
{
(void)0;
}
[/code]

am I asking for too much?

CORRECTION: Sorry, that was wrong, for(...){ (void)0; } does get removed!

[jabbah]

yet another correction: seemingly the (void)0; is removed but the (then empty) loop is not ... anyways ...

back to my orignial question - just in case anybody cares - ive not managed to get something that can be #define'd to (void)0 that can be used like a stream but now I have a bunch of macros like

[code=c]
#define logstream2( stream, m1, m2 ) \
if (true) { \
ostream& log_stream = stream; \
log_stream << m1 << m2; \
} else (void)0
[/code]
(and also logstream1, logstream3, etc)

This hasnt got the same interface as stream, ie operator<<(), but its the best I was able to achieve.