Re: Anonymous union rules against constructors & assignment

<johnchx2@yahoo.com> wrote in message
news:1149633364.561734.56320@i39g2000cwa.googlegroups.com...


'memcpy doesn't work on non-PODs' !!!

Wow! That's bad news.

So, let's say I had this:

class A {... }* a;

foo()
{void* p=malloc(sizeof(A));

 new(p) A();

 a=(A*)malloc(sizeof(A));

 memcpy(a,p,sizeof(A)); // Doesn't work if A is non-POD?

 free(p);

 a->method();

 delete a;
}

If memcpy doesn't work on non-POD objects then something truly fundamental
has changed, e.g. C++ has become C#.

I don't care how non-POD objects are laid out, because I don't intend to
exploit their layout. I only require that I have the option that I may
overlay their storage with other data, AND that I be given credit for
knowing that the non-POD objects may require construction with placement
new, may require custom non-default assignment, and may require destruction.

All that's required is changing a compiler error to a warning:

"Error: Union member object must have default assign-copy operator"
to
"Warning: Union member object does not have default assign-copy operator"

That's all. It's such a weeny little thing.

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