Boost C++ Libraries

Nowadays, every C++ developer is familiar with the Resource Acquisition Is Initialization (RAII) technique. It binds resource acquisition and release to initialization and destruction of a variable that holds the resource. There are times when writing a special class for such a variable is not worth the effort. This is when Boost.ScopeExit comes into play.

Programmers can put resource acquisition directly in their code and next to it, they can write code that releases the resource using this library. For example (see also world.cpp): ^[1]

void world::add_person(person const& a_person) {
    bool commit = false;

    persons_.push_back(a_person);           // (1) direct action
    // Following block is executed when the enclosing scope exits.
    BOOST_SCOPE_EXIT(&commit, &persons_) {
        if(!commit) persons_.pop_back();    // (2) rollback action
    } BOOST_SCOPE_EXIT_END

    // ...                                  // (3) other operations

    commit = true;                          // (4) disable rollback actions
}