Manipulators

[Barguast]

I've got a HTML-based Log class which I've designed to work in the same way as streams to allow for formatting. Now I want to have a manipulator similar to endl which will insert <BR> at the current position.

Can someone tell me how to code a manipulator like this?

[CornedBee]

The typical stream manipulator is simply a function that takes a single argument, in its full versions:

// Flag manipulator
ios_base &name(ios_base &stream) {
  // insertion/extraction action
  return stream;
}

// State manipulator
template<typename C, typename T = std::char_traits<C> >
basic_ios<C, T> &name(basic_ios<C, T> &stream) {
  return stream;
}

// Input manipulator
template<typename C, typename T = std::char_traits<C> >
basic_istream<C, T> &name(basic_istream<C, T> &stream) {
  return stream;
}

// Output manipulator
template<typename C, typename T = std::char_traits<C> >
basic_ostream<C, T> &name(basic_ostream<C, T> &stream) {
  return stream;
}

The << and >> operators are overloaded to allow such functions to be inserted, the operators then call the function.


Parametrized manipulators like setw are something different.