[scope] The comparison with Boost.ScopeExit is unfair

From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2023-12-01 17:25:50

Hi All,
This is not a review yet. I am just looking at the front page of the docs,
and I think the comparison with Boost.ScopeGuard is unfair.

You are comparing C++03 Boost.ScopeGuard with C++11 Boost.Scope. Try
comparing it with C++03 Boost.Scope.
Otherwise compare C++11 to C++11, and there Boost.ScopeGuard has a nicer
syntax:

 int compute()
    {
        // Reset variables on return
        BOOST_SCOPE_EXIT(this_)
        {
            this_->x = 0;
            this_->y = 0;
        };

        return x + y;
    }

Regarding the example with exceptions, nobody would use
Boost.ScopeGuard like this. A robust usage is in Boost.ScopeGuard's
docs:

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
    };

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

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

}

Which is longer, but usable in coroutines. Whereas Boost.Scope's
solution is not usable in coroutines.

Only after these changes are applied, I think is the comparison fair.

Regards,

&rzej;