Re: Garbage collection in C++

From:

anon <anon@no.invalid>

Newsgroups:

comp.lang.c++

Date:

Tue, 18 Nov 2008 15:35:09 +0100

Message-ID:

<gfujqs$3n9$1@news01.versatel.de>

Chris M. Thomasson wrote:

"James Kanze" <james.kanze@gmail.com> wrote in message
news:39609efb-1a8d-4a37-8daa-f12dc1b2159a@w1g2000prk.googlegroups.com...
On Nov 16, 3:54 pm, Sam <s...@email-scan.com> wrote:
[...]

So they seek for a security blanket called "garbage
collection", so they don't have to worry about it, and can
proceed to churn out their spaghetti code without worry, just
like they do in Java.

That is, of course, the most obvious bullshit I've ever seen.
There are cases where garbage collection isn't appropriate, and
cases where it is necessary.

Humm.. Can you give an example or two of a scenario in which a GC is
absolutely required/necessary? For some reason, I can't seem to think of
one off the top of my head. What am I missing? Perhaps I misunderstand
your use of the word "necessary"...

1) without gc

class A
{
};

A* foo()
{
   A *a = NULL;
   A *b = NULL;

   a = new A;
   try
   {
     b = new A;
   }
   catch(...)
   {
     delete(a);
   }

   // do something

   return a;
}

2) with GC
class A
{
};

A* foo()
{
   std::auto_ptr< A > a( new A );
   std::auto_ptr< A > b( new A );

   // do something

   return a.release();
}

Would this do?

Another example:

class X
{
   public:
     X()
     {
       throw 1111;
     }
};

class A
{
public:
   A() : a( new int ), b( new X )
   {
   }
// memory leak when b throws

   int *a;
   X *b;
};

vs

class A
{
public:
   A() : a( new int ), b( new X )
   {
   }
// OK

   std::auto_ptr< int > a;
   std::auto_ptr< X > b;
};