Re: doubt related to 'new' in MFC
David Ching wrote:
"Doug Harrison [MVP]" <dsh@mvps.org> wrote in message
news:pa6q83daglle64295srne9bjsudbeglts6@4ax.com...
If you are using delete, you're probably writing code that is not
exception-safe. Use smart pointers instead.
Would you further explain this? How is using delete not exception safe? Is
it simply because the code which calls delete may not be executed if there
is an exception? Would moving such code to the finally block fix this?
It's not obvious to me how smart pointers are any better at this, other than
the dtor is always called, but the the delete call would always as well, if
it were in a finally block.
Why? If the object is to exist until the program terminates, and its
clean-up involves nothing the OS won't do, it's a waste of time to delete
it, or even for the compiler to arrange to call a destructor for an object
that has static storage duration.
The reason I religiously delete all data members that I new is because I
don't want to assume how my class is going to be used, and what it's
expected lifetime is. This is different than perhaps what you are talking
about, but in these days of rampant copy/paste, your code that merely
instantiates a global var for the lifetime of an app could easily be copied
into a method of an object whose lifetime is more transient.
David:
Standard C++ does not have a finally concept, but with RAII it is not
needed. The RAII idiom ensures that memory or other resources are always
released automatically, whether or not exceptions are thrown.
In RAII, uses of new and new [] are always wrapped, e.g. by
std::auto_ptr or std::vector, and so no explicit delete's or delete []'s
appear in client code.
But I agree with you and the other David that, one way or another, all
memory and resources should be released before program termination. Not
to do so gives me the shivers also.
--
David Wilkinson
Visual C++ MVP