Re: [boost] try... catch... finally?

From: Andrey Semashev (andysem_at_[hidden])
Date: 2007-04-09 02:07:31

Hello Gregory,

Monday, April 9, 2007, 4:36:36 AM, you wrote:

> Well, I'm very late to this thread of discussion, but I'd like to add my
> $0.02.

> Why would we go through so much complexity? Remember the simple and basic
> principle of RAII? In situations like this, you just make a simple wrapper
> of the FILE*, with an implementation similar to that of a smart pointer such
> as the auto_ptr, and let's name it auto_cfile, with a "FILE*&()" operator
> member function to expose the FILE* it protects:

> auto_cfile f(std::fopen("/etc/passwd","r"));
> ..... (uses of  f as if it were a FILE*)

> and the FILE* is automatically closed by auto_cfile's dtor when it goes out
> of scope.

> No need of a "try ... catch" block at all, much less of "finally," which is
> an unnecessary addition in C#, IMHO.

> <snip>

In a case as simple as FILE* I may agree with you. But sometimes I
have to do something more complicated than fclose, and this something
is not associated with any handle like FILE*. For example, I can
express the code to be executed inevitably, even if an exception
occurs at some point, as a scope guard.

void foo()
{
  // some code here...

  BOOST_SCOPE_GUARD_BEGIN(whatever)
  {
    // This code is executed even if the function below
    // throws. This function may be out of this module's
    // scope, so I generally don't know (and don't care)
    // wether it does throw or not, and if it does, what
    // it does throw.
  }
  BOOST_SCOPE_GUARD_END;

  bar();
}

Another good use case for scope guards is making rollbackable code.
But I see, this implementation doesn't support that.

-- 
Best regards,
 Andrey                            mailto:andysem_at_[hidden]