blog: jl_signal, code: iterating through signal connections

gistfile1.cpp

// A sample Emit() method on a signal object for slots that take
// two arguments.
void Emit( TArg1 a1, TArg2 a2 ) const
{
    // Here, the iterator is just a pointer to a list node.
    // Incrementing the iterator means that we just follow the node's
    // "next" pointer. But what happens if the current node is freed
    // before the iterator can be incremented?
    for ( ConnectionListIter i = m_oConnections.begin();
          i.isValid();
          ++i )
    {
        i->delegate.invoke( a1, a2 );
    }

    // I also considered the following design, which solves the
    // above problem by moving it to a different location.
    // What if, by invoking the delegate, we disconnect the NEXT
    // delegate? We're still left with a corrupt iterator.
    ConnectionListIter i = m_oConnections.begin();
    while ( i.isValid() )
    {
        ConnectionNode* c = *i;
        ++i;
        c->delegate.invoke( a1, a2 );
    }
}