On quinta-feira, 2 de agosto de 2012 16.02.43, Marc Mutz wrote: > Need to be careful with templates. Can't use add the unrestricted noexcept > there, need to use noexcept(noexcept(expr)), which is even uglier
template<typename T> inline uint qHash(const T &t, uint seed)
Q_DECL_NOEXCEPT_EXPR(noexcept(qHash(t)))
{ return (qHash(t) ^ seed); }
template <typename T1, typename T2> inline uint qHash(const QPair<T1, T2>
&key, uint seed = 0)
Q_DECL_NOEXCEPT_EXPR(noexcept(qHash(key.first, seed)) &&
noexcept(qHash(key.second, seed)))
{
...
}
By the way, I'm running into an issue which I'm not entirely sure whether it's
a design issue. Imagine this case:
class Object
{
void f();
void g() noexcept(same noexcept status as f);
};
That is, I want to declare g to be as noexcept as its sibling function f. How?
All of these options fail:
noexcept(noexcept(f))
-> evaluates to true
noexcept(noexcept(Object::f))
-> error: invalid use of non-static member function ‘void Object::f()'
noexcept(noexcept(f()))
-> error: cannot call member function ‘void Object::f()’ without object
noexcept(noexcept(this->f()))
-> error: invalid use of ‘this’ at top level
noexcept(noexcept(Object().f()))
-> error: invalid use of incomplete type ‘struct Object’
Any suggestions?
My actual use-case is of a function declared in a base-class: I want
QMutex::lock() to be noexcept if QBasicMutex::lockInternal() is noexcept. In
that particular case, it works like this:
class QMutex : public QBasicMutex
{
static QBasicMutex *dummyBasicMutex() noexcept;
public:
void lock() noexcept(noexcept(dummyBasicMutex()->lockInternal()));
};
But it's ugly.
--
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
Software Architect - Intel Open Source Technology Center
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