[openbeos] Re: [OT] Re: Pointer or reference?

  • From: "Steve Folta" <steve@xxxxxxxxx>
  • To: <openbeos@xxxxxxxxxxxxx>
  • Date: Thu, 1 Apr 2004 00:12:17 -0800 (PST)

"Scott MacMaster" <scott@xxxxxxxxxxxxxxxxxx> wrote:
> If an object deletes itself then that applies [sic: implies?] that the
> object is the owner of itself.  In c++ programs this is never.  Thus an
> object in c++ should never delete itself.

This is wrong.  The concept of ownership is not even expressible in C++. 
So there are no constraints on who can own whom.  Certainly an object can
own itself.  As someone else pointed out, a reference-counted object can
be considered self-owning -- and that's a well-known idiom that can even
be found in Stroustrop.

I created a language where ownership *was* expressed, and was the basis of
all memory management.  But I never got it fully working well, and in the
end I ripped it out and put in a garbage collector.

>> This is also why creating objects on
>> the stack is incorrect. An automatic (stack) variable can only be
>> accessed from the thread that created it.
> That's definitely wrong.  I'm certain I've accessed the stack from a
> seperate thread.  In any case, I decided to run a test program.  I
> initialized a int to 10 in one thread, later I displayed and changed the
> value in another thread, the back in the first thread I displayed the
> value again.  Everything worked perfectly and as expected.

It can be done, but it requires very careful synchronization of the
threads.  I'd consider it a bad practice.

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