[ale] Q: directing stream I/O _the_C++_way_

[John Mills]

Fletch --


On Sat, 27 Nov 2004, Fletch wrote:

> I want to say that you should be able to declare an ostream and assign
> either an ofstream or cout as desired.
> 
> ostream& log;  <-------[initializing to 'cout' => same whine]-----+
>                                                                   |
> if( logfilename ) {                                               |
>   ofstream logfile( logfilename.c_str() );                        |
>   log = logfile;                                                  |
    ^^^^^^^^^^^^^---- This doesn't compile. I get:                  |
                                                                    V
Switchbox.cpp:38: `logging' declared as reference but not initialized
/usr/include/c++/3.2.3/bits/ios_base.h: In member function 
   `std::basic_ios<char, std::char_traits<char> >& std::basic_ios<char, 
   std::char_traits<char> >::operator=(const std::basic_ios<char, 
   std::char_traits<char> >&)':
/usr/include/c++/3.2.3/bits/ios_base.h:427: `std::ios_base& 
   std::ios_base::operator=(const std::ios_base&)' is private
Switchbox.cpp:133: within this context
make: *** [Switchbox.o] Error 1

> } else {
>   log = cout;
> }

 - John Mills
   john.m.mills at alum.mit.edu