🚀 go-pugleaf

someone <someone@somewhere.com> writes:

> Does anyone know how to send "cout" to TMemo instead of sending it
> to console?

The Standard C++ Library is designed to allow this sort of tweaking.

C++ streams (such as std::cout) are of type std::ostream and have a
data member of type (pointer to) std::streambuf. std::ostream is
responsible for formatting (i.e. converting any kind of data into a
stream of characters); std::streambuf is the base class for classes
that forward that stream of characters to the console, a file, a
socket etc.

Obviously, what you want to do is to derive your own class from
std::streambuf, which, instead of forwarding the character stream to
the console or a file, adds it to a TMemo object.

This is an outline of how to do that:


Create your streambuf class:

class memo_streambuf : public std::streambuf
{
  public:
    memo_streambuf(TMemo &);

  protected:
    virtual int overflow(int c);

  private:
    TMemo &myBackend;
};

memo_streambuf::memo_streambuf(TMemo &m)
  : myBackend(m)
{
}

//virtual
int memo_streambuf::overflow(int c)
{
  if (c!=EOF)
    ; // append c to myBackend - I'm sure you know how to do that

  return c;
}


memo_streambuf is sort of a misnomer, because it doesn't have a
buffer. Therefore, overflow() will be called for each character.


Somewhere in your program, configure std::cout to use a memo_streambuf
object as its streambuf instead what it would use by default:

std::streambuf *savebuf;

void somefunc()
{
  savebuf = std::cout.rdbuf(new memo_streambuf(theMemo));
}


Later, before the program terminates, reset std::cout to its initial
streambuf object, and delete the memo_streambuf object:

void someotherfunc()
{
  delete std::cout.rdbuf(savebuf);
}