Re: what is the semantic of a ref to a function or functor
tomgee wrote:
class factorial
{
public:
[...]
void operator()() { ... }
int result() const { return res; }
[...]
};
factorial f(10);
boost::thread thrd(boost::ref(f));
// boost::thread thrd(f) would result in f.result()==0
I happen to find that if I remove boost::ref from boost::thread
thrd(boost::ref(f)); the result would result in f.result() changing
from a correct value(3628800) to 0.
Well, I would say that the correct value is zero, just that it is not the
one you expected. The thing you are falling over is the fact that 'f' is
copied, so the factorial doing the computation and the one from which you
request the result are two different instances.
Note: for such cases, I wouldn't normally overload operator() for this but
instead use boost::bind() to create a functor and use a natural name for
the function that does the computation. That way, the glue-code between the
program logic and boost::thread is concentrated in one place.
Uli
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