Re: [boost] [scope_guard] New revision available + naming consideration

From: Rob Stewart (stewart_at_[hidden])
Date: 2005-09-22 14:44:41

From: Jason Stewart <jstewart_at_[hidden]>
> 
> However, maybe using the shared_ptr semantics would work. I.e. if you 
> can create a guard that is "uninitialized" and then reset it later to 
> an active guard.
> 
> {
>          scope_guard g;
> 
>          if (some condition)
>          {
>                  g = scope_guard(my_undo_function);
>                  // do something here
>          }
> 
>          if (some other condition)
>          {
>                  // we changed our mind, dismiss it.
>                  g = scope_guard;
> 
>                  // or ...
>                  // g.dismiss();
>                  // g.reset(); // like shared_ptr
>          }
> }
> 
> It seems to me that is as easy to read as having an explicit "guard" 
> or "activate" command is. I confess though that I didn't follow the 
> early discussion closely so I apologize is this has been discussed already.

You're missing the usage of wanting to keep the original undo
behavior, ignore it in some portion of the code, and then
reinstate it later.  With the above, it appears that would entail
this sort of usage:

   scope_guard g(my_undo_function);
   ...
   g = scope_guard();
   ...
   g = scope_guard(my_undo_function);
   ...

That introduces a maintenance problem.  With the names we're
discussing, you'd write this instead:

   scope_guard g(my_undo_function);
   ...
   g.dismiss(); // or whatever name is selected
   ...
   g.protect(); // or whatever name is selected
   ...

-- 
Rob Stewart                           stewart_at_[hidden]
Software Engineer                     http://www.sig.com
Susquehanna International Group, LLP  using std::disclaimer;