On 1/26/2013 8:17 AM, Rainer Schuetze wrote:
On 26.01.2013 16:53, deadalnix wrote:
On Saturday, 26 January 2013 at 10:52:59 UTC, Rainer Schuetze wrote:
On 26.01.2013 11:40, Johannes Pfau wrote:
Yes, I just wanted to point out a common source for such bugs, it's not
the GC's fault. It's great that the documentation of toStringz mentions
that issue. What I meant is most of the time we use toStringz() like
this:
string str;
c_function(str.toStringz());
This is only valid if c_function doesn't store the pointer, but newbies
might miss that and just copy this nice looking example code for other
c functions. There's nothing we can do about that though, interfacing
to C just is a little bit dangerous.
It is even dangerous if it is only used temporarily during that
function call, but copied elsewhere in the C heap and cleared on the
stack:
struct param_struct { const char* name; };
void c_function(const char*p)
{
param_struct* ps = new param_struct;
ps->name = p;
p = 0;
doSomething(ps);
delete ps;
}
Imagine a garbage collection while executing doSomething...
That isn't an issue as the pointer will e found at upper level in the
stack anyway.
"p = 0;" clears the only existing reference on the stack.
No, because ps is on the stack, and ps points to a copy of p. Hence, that code
snippet is GC safe.
