1 /****************************************************************************
2 **
3 ** DQt - D bindings for the Qt Toolkit
4 **
5 ** GNU Lesser General Public License Usage
6 ** This file may be used under the terms of the GNU Lesser
7 ** General Public License version 3 as published by the Free Software
8 ** Foundation and appearing in the file LICENSE.LGPL3 included in the
9 ** packaging of this file. Please review the following information to
10 ** ensure the GNU Lesser General Public License version 3 requirements
11 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
12 **
13 ****************************************************************************/
14 module qt.core.objectdefs_impl;
15 extern(C++):
16 
17 import qt.config;
18 import qt.core.atomic;
19 import qt.core.object;
20 import qt.helpers;
21 
22 /+ #ifndef QOBJECTDEFS_H
23 #error Do not include qobjectdefs_impl.h directly
24 #endif
25 
26 #if 0
27 #pragma qt_sync_skip_header_check
28 #pragma qt_sync_stop_processing
29 #endif
30 
31 class QObject; +/
32 
33 extern(C++, "QtPrivate") {
34     /+ template <typename T> struct RemoveRef { typedef T Type; };
35     template <typename T> struct RemoveRef<T&> { typedef T Type; };
36     template <typename T> struct RemoveConstRef { typedef T Type; };
37     template <typename T> struct RemoveConstRef<const T&> { typedef T Type; };
38 
39     /*
40        The following List classes are used to help to handle the list of arguments.
41        It follow the same principles as the lisp lists.
42        List_Left<L,N> take a list and a number as a parameter and returns (via the Value typedef,
43        the list composed of the first N element of the list
44      */
45     // With variadic template, lists are represented using a variadic template argument instead of the lisp way
46     template <typename...> struct List {};
47     template <typename Head, typename... Tail> struct List<Head, Tail...> { typedef Head Car; typedef List<Tail...> Cdr; };
48     template <typename, typename> struct List_Append;
49     template <typename... L1, typename...L2> struct List_Append<List<L1...>, List<L2...>> { typedef List<L1..., L2...> Value; };
50     template <typename L, int N> struct List_Left {
51         typedef typename List_Append<List<typename L::Car>,typename List_Left<typename L::Cdr, N - 1>::Value>::Value Value;
52     };
53     template <typename L> struct List_Left<L, 0> { typedef List<> Value; };
54     // List_Select<L,N> returns (via typedef Value) the Nth element of the list L
55     template <typename L, int N> struct List_Select { typedef typename List_Select<typename L::Cdr, N - 1>::Value Value; };
56     template <typename L> struct List_Select<L,0> { typedef typename L::Car Value; };
57 
58     /*
59        trick to set the return value of a slot that works even if the signal or the slot returns void
60        to be used like     function(), ApplyReturnValue<ReturnType>(&return_value)
61        if function() returns a value, the operator,(T, ApplyReturnValue<ReturnType>) is called, but if it
62        returns void, the builtin one is used without an error.
63     */
64     template <typename T>
65     struct ApplyReturnValue {
66         void *data;
67         explicit ApplyReturnValue(void *data_) : data(data_) {}
68     };
69     template<typename T, typename U>
70     void operator,(T &&value, const ApplyReturnValue<U> &container) {
71         if (container.data)
72             *reinterpret_cast<U *>(container.data) = std::forward<T>(value);
73     } +/
74     /+void operator ,(T)(T, ref const(ApplyReturnValue!(void)) ) {}+/
75 
76 
77     /*
78       The FunctionPointer<Func> struct is a type trait for function pointer.
79         - ArgumentCount  is the number of argument, or -1 if it is unknown
80         - the Object typedef is the Object of a pointer to member function
81         - the Arguments typedef is the list of argument (in a QtPrivate::List)
82         - the Function typedef is an alias to the template parameter Func
83         - the call<Args, R>(f,o,args) method is used to call that slot
84             Args is the list of argument of the signal
85             R is the return type of the signal
86             f is the function pointer
87             o is the receiver object
88             and args is the array of pointer to arguments, as used in qt_metacall
89 
90        The Functor<Func,N> struct is the helper to call a functor of N argument.
91        its call function is the same as the FunctionPointer::call function.
92      */
93     /+ template<class T> using InvokeGenSeq = typename T::Type;
94 
95     template<int...> struct IndexesList { using Type = IndexesList; };
96 
97     template<int N, class S1, class S2> struct ConcatSeqImpl;
98 
99     template<int N, int... I1, int... I2>
100     struct ConcatSeqImpl<N, IndexesList<I1...>, IndexesList<I2...>>
101         : IndexesList<I1..., (N + I2)...>{};
102 
103     template<int N, class S1, class S2>
104     using ConcatSeq = InvokeGenSeq<ConcatSeqImpl<N, S1, S2>>;
105 
106     template<int N> struct GenSeq;
107     template<int N> using makeIndexSequence = InvokeGenSeq<GenSeq<N>>;
108 
109     template<int N>
110     struct GenSeq : ConcatSeq<N/2, makeIndexSequence<N/2>, makeIndexSequence<N - N/2>>{};
111 
112     template<> struct GenSeq<0> : IndexesList<>{};
113     template<> struct GenSeq<1> : IndexesList<0>{};
114 
115     template<int N>
116     struct Indexes { using Value = makeIndexSequence<N>; };
117 
118     template<typename Func> struct FunctionPointer { enum {ArgumentCount = -1, IsPointerToMemberFunction = false}; };
119 
120     template <typename, typename, typename, typename> struct FunctorCall;
121     template <int... II, typename... SignalArgs, typename R, typename Function>
122     struct FunctorCall<IndexesList<II...>, List<SignalArgs...>, R, Function> {
123         static void call(Function &f, void **arg) {
124             f((*reinterpret_cast<typename RemoveRef<SignalArgs>::Type *>(arg[II+1]))...), ApplyReturnValue<R>(arg[0]);
125         }
126     };
127     template <int... II, typename... SignalArgs, typename R, typename... SlotArgs, typename SlotRet, class Obj>
128     struct FunctorCall<IndexesList<II...>, List<SignalArgs...>, R, SlotRet (Obj::*)(SlotArgs...)> {
129         static void call(SlotRet (Obj::*f)(SlotArgs...), Obj *o, void **arg) {
130             (o->*f)((*reinterpret_cast<typename RemoveRef<SignalArgs>::Type *>(arg[II+1]))...), ApplyReturnValue<R>(arg[0]);
131         }
132     };
133     template <int... II, typename... SignalArgs, typename R, typename... SlotArgs, typename SlotRet, class Obj>
134     struct FunctorCall<IndexesList<II...>, List<SignalArgs...>, R, SlotRet (Obj::*)(SlotArgs...) const> {
135         static void call(SlotRet (Obj::*f)(SlotArgs...) const, Obj *o, void **arg) {
136             (o->*f)((*reinterpret_cast<typename RemoveRef<SignalArgs>::Type *>(arg[II+1]))...), ApplyReturnValue<R>(arg[0]);
137         }
138     };
139 #if defined(__cpp_noexcept_function_type) && __cpp_noexcept_function_type >= 201510
140     template <int... II, typename... SignalArgs, typename R, typename... SlotArgs, typename SlotRet, class Obj>
141     struct FunctorCall<IndexesList<II...>, List<SignalArgs...>, R, SlotRet (Obj::*)(SlotArgs...) noexcept> {
142         static void call(SlotRet (Obj::*f)(SlotArgs...) noexcept, Obj *o, void **arg) {
143             (o->*f)((*reinterpret_cast<typename RemoveRef<SignalArgs>::Type *>(arg[II+1]))...), ApplyReturnValue<R>(arg[0]);
144         }
145     };
146     template <int... II, typename... SignalArgs, typename R, typename... SlotArgs, typename SlotRet, class Obj>
147     struct FunctorCall<IndexesList<II...>, List<SignalArgs...>, R, SlotRet (Obj::*)(SlotArgs...) const noexcept> {
148         static void call(SlotRet (Obj::*f)(SlotArgs...) const noexcept, Obj *o, void **arg) {
149             (o->*f)((*reinterpret_cast<typename RemoveRef<SignalArgs>::Type *>(arg[II+1]))...), ApplyReturnValue<R>(arg[0]);
150         }
151     };
152 #endif
153 
154     template<class Obj, typename Ret, typename... Args> struct FunctionPointer<Ret (Obj::*) (Args...)>
155     {
156         typedef Obj Object;
157         typedef List<Args...>  Arguments;
158         typedef Ret ReturnType;
159         typedef Ret (Obj::*Function) (Args...);
160         enum {ArgumentCount = sizeof...(Args), IsPointerToMemberFunction = true};
161         template <typename SignalArgs, typename R>
162         static void call(Function f, Obj *o, void **arg) {
163             FunctorCall<typename Indexes<ArgumentCount>::Value, SignalArgs, R, Function>::call(f, o, arg);
164         }
165     };
166     template<class Obj, typename Ret, typename... Args> struct FunctionPointer<Ret (Obj::*) (Args...) const>
167     {
168         typedef Obj Object;
169         typedef List<Args...>  Arguments;
170         typedef Ret ReturnType;
171         typedef Ret (Obj::*Function) (Args...) const;
172         enum {ArgumentCount = sizeof...(Args), IsPointerToMemberFunction = true};
173         template <typename SignalArgs, typename R>
174         static void call(Function f, Obj *o, void **arg) {
175             FunctorCall<typename Indexes<ArgumentCount>::Value, SignalArgs, R, Function>::call(f, o, arg);
176         }
177     };
178 
179     template<typename Ret, typename... Args> struct FunctionPointer<Ret (*) (Args...)>
180     {
181         typedef List<Args...> Arguments;
182         typedef Ret ReturnType;
183         typedef Ret (*Function) (Args...);
184         enum {ArgumentCount = sizeof...(Args), IsPointerToMemberFunction = false};
185         template <typename SignalArgs, typename R>
186         static void call(Function f, void *, void **arg) {
187             FunctorCall<typename Indexes<ArgumentCount>::Value, SignalArgs, R, Function>::call(f, arg);
188         }
189     };
190 
191 #if defined(__cpp_noexcept_function_type) && __cpp_noexcept_function_type >= 201510
192     template<class Obj, typename Ret, typename... Args> struct FunctionPointer<Ret (Obj::*) (Args...) noexcept>
193     {
194         typedef Obj Object;
195         typedef List<Args...>  Arguments;
196         typedef Ret ReturnType;
197         typedef Ret (Obj::*Function) (Args...) noexcept;
198         enum {ArgumentCount = sizeof...(Args), IsPointerToMemberFunction = true};
199         template <typename SignalArgs, typename R>
200         static void call(Function f, Obj *o, void **arg) {
201             FunctorCall<typename Indexes<ArgumentCount>::Value, SignalArgs, R, Function>::call(f, o, arg);
202         }
203     };
204     template<class Obj, typename Ret, typename... Args> struct FunctionPointer<Ret (Obj::*) (Args...) const noexcept>
205     {
206         typedef Obj Object;
207         typedef List<Args...>  Arguments;
208         typedef Ret ReturnType;
209         typedef Ret (Obj::*Function) (Args...) const noexcept;
210         enum {ArgumentCount = sizeof...(Args), IsPointerToMemberFunction = true};
211         template <typename SignalArgs, typename R>
212         static void call(Function f, Obj *o, void **arg) {
213             FunctorCall<typename Indexes<ArgumentCount>::Value, SignalArgs, R, Function>::call(f, o, arg);
214         }
215     };
216 
217     template<typename Ret, typename... Args> struct FunctionPointer<Ret (*) (Args...) noexcept>
218     {
219         typedef List<Args...> Arguments;
220         typedef Ret ReturnType;
221         typedef Ret (*Function) (Args...) noexcept;
222         enum {ArgumentCount = sizeof...(Args), IsPointerToMemberFunction = false};
223         template <typename SignalArgs, typename R>
224         static void call(Function f, void *, void **arg) {
225             FunctorCall<typename Indexes<ArgumentCount>::Value, SignalArgs, R, Function>::call(f, arg);
226         }
227     };
228 #endif
229 
230     template<typename Function, int N> struct Functor
231     {
232         template <typename SignalArgs, typename R>
233         static void call(Function &f, void *, void **arg) {
234             FunctorCall<typename Indexes<N>::Value, SignalArgs, R, Function>::call(f, arg);
235         }
236     };
237 
238     /*
239         Logic that checks if the underlying type of an enum is signed or not.
240         Needs an external, explicit check that E is indeed an enum. Works
241         around the fact that it's undefined behavior to instantiate
242         std::underlying_type on non-enums (cf. §20.13.7.6 [meta.trans.other]).
243     */
244     template<typename E, typename Enable = void>
245     struct IsEnumUnderlyingTypeSigned : std::false_type
246     {
247     };
248 
249     template<typename E>
250     struct IsEnumUnderlyingTypeSigned<E, typename std::enable_if<std::is_enum<E>::value>::type>
251             : std::integral_constant<bool, std::is_signed<typename std::underlying_type<E>::type>::value>
252     {
253     };
254 
255     /*
256        Logic that checks if the argument of the slot does not narrow the
257        argument of the signal when used in list initialization. Cf. §8.5.4.7
258        [dcl.init.list] for the definition of narrowing.
259        For incomplete From/To types, there's no narrowing.
260     */
261     template<typename From, typename To, typename Enable = void>
262     struct AreArgumentsNarrowedBase : std::false_type
263     {
264     };
265 
266     template <typename T>
267     using is_bool = std::is_same<bool, typename std::decay<T>::type>;
268 
269     template<typename From, typename To>
270     struct AreArgumentsNarrowedBase<From, To, typename std::enable_if<sizeof(From) && sizeof(To)>::type>
271         : std::integral_constant<bool,
272               (std::is_floating_point<From>::value && std::is_integral<To>::value) ||
273               (std::is_floating_point<From>::value && std::is_floating_point<To>::value && sizeof(From) > sizeof(To)) ||
274               ((std::is_pointer<From>::value || std::is_member_pointer<From>::value) && QtPrivate::is_bool<To>::value) ||
275               ((std::is_integral<From>::value || std::is_enum<From>::value) && std::is_floating_point<To>::value) ||
276               (std::is_integral<From>::value && std::is_integral<To>::value
277                && (sizeof(From) > sizeof(To)
278                    || (std::is_signed<From>::value ? !std::is_signed<To>::value
279                        : (std::is_signed<To>::value && sizeof(From) == sizeof(To))))) ||
280               (std::is_enum<From>::value && std::is_integral<To>::value
281                && (sizeof(From) > sizeof(To)
282                    || (IsEnumUnderlyingTypeSigned<From>::value ? !std::is_signed<To>::value
283                        : (std::is_signed<To>::value && sizeof(From) == sizeof(To)))))
284               >
285     {
286     };
287 
288     /*
289        Logic that check if the arguments of the slot matches the argument of the signal.
290        To be used like this:
291        Q_STATIC_ASSERT(CheckCompatibleArguments<FunctionPointer<Signal>::Arguments, FunctionPointer<Slot>::Arguments>::value)
292     */
293     template<typename A1, typename A2> struct AreArgumentsCompatible {
294         static int test(const typename RemoveRef<A2>::Type&);
295         static char test(...);
296         static const typename RemoveRef<A1>::Type &dummy();
297         enum { value = sizeof(test(dummy())) == sizeof(int) };
298 #ifdef QT_NO_NARROWING_CONVERSIONS_IN_CONNECT
299         using AreArgumentsNarrowed = AreArgumentsNarrowedBase<typename RemoveRef<A1>::Type, typename RemoveRef<A2>::Type>;
300         Q_STATIC_ASSERT_X(!AreArgumentsNarrowed::value, "Signal and slot arguments are not compatible (narrowing)");
301 #endif
302     };
303     template<typename A1, typename A2> struct AreArgumentsCompatible<A1, A2&> { enum { value = false }; };
304     template<typename A> struct AreArgumentsCompatible<A&, A&> { enum { value = true }; };
305     // void as a return value
306     template<typename A> struct AreArgumentsCompatible<void, A> { enum { value = true }; };
307     template<typename A> struct AreArgumentsCompatible<A, void> { enum { value = true }; };
308     template<> struct AreArgumentsCompatible<void, void> { enum { value = true }; };
309 
310     template <typename List1, typename List2> struct CheckCompatibleArguments { enum { value = false }; };
311     template <> struct CheckCompatibleArguments<List<>, List<>> { enum { value = true }; };
312     template <typename List1> struct CheckCompatibleArguments<List1, List<>> { enum { value = true }; };
313     template <typename Arg1, typename Arg2, typename... Tail1, typename... Tail2>
314     struct CheckCompatibleArguments<List<Arg1, Tail1...>, List<Arg2, Tail2...>>
315     {
316         enum { value = AreArgumentsCompatible<typename RemoveConstRef<Arg1>::Type, typename RemoveConstRef<Arg2>::Type>::value
317                     && CheckCompatibleArguments<List<Tail1...>, List<Tail2...>>::value };
318     };
319 
320     /*
321        Find the maximum number of arguments a functor object can take and be still compatible with
322        the arguments from the signal.
323        Value is the number of arguments, or -1 if nothing matches.
324      */
325     template <typename Functor, typename ArgList> struct ComputeFunctorArgumentCount;
326 
327     template <typename Functor, typename ArgList, bool Done> struct ComputeFunctorArgumentCountHelper
328     { enum { Value = -1 }; };
329     template <typename Functor, typename First, typename... ArgList>
330     struct ComputeFunctorArgumentCountHelper<Functor, List<First, ArgList...>, false>
331         : ComputeFunctorArgumentCount<Functor,
332             typename List_Left<List<First, ArgList...>, sizeof...(ArgList)>::Value> {};
333 
334     template <typename Functor, typename... ArgList> struct ComputeFunctorArgumentCount<Functor, List<ArgList...>>
335     {
336         template <typename D> static D dummy();
337         template <typename F> static auto test(F f) -> decltype(((f.operator()((dummy<ArgList>())...)), int()));
338         static char test(...);
339         enum {
340             Ok = sizeof(test(dummy<Functor>())) == sizeof(int),
341             Value = Ok ? int(sizeof...(ArgList)) : int(ComputeFunctorArgumentCountHelper<Functor, List<ArgList...>, Ok>::Value)
342         };
343     };
344 
345     /* get the return type of a functor, given the signal argument list  */
346     template <typename Functor, typename ArgList> struct FunctorReturnType;
347     template <typename Functor, typename ... ArgList> struct FunctorReturnType<Functor, List<ArgList...>> {
348         template <typename D> static D dummy();
349         typedef decltype(dummy<Functor>().operator()((dummy<ArgList>())...)) Value;
350     }; +/
351 
352     // internal base class (interface) containing functions required to call a slot managed by a pointer to function.
353     extern(C++, class) struct QSlotObjectBase {
354     private:
355         QAtomicInt m_ref;
356         // don't use virtual functions here; we don't want the
357         // compiler to create tons of per-polymorphic-class stuff that
358         // we'll never need. We just use one function pointer.
359         alias ImplFn = ExternCPPFunc!(void function(int which, QSlotObjectBase* this_, QObject receiver, void** args, bool* ret));
360         const(ImplFn) m_impl;
361     protected:
362         enum Operation {
363             Destroy,
364             Call,
365             Compare,
366 
367             NumOperations
368         }
369     public:
370         /+ explicit +/this(ImplFn fn)
371         {
372             this.m_ref = QAtomicInt(1);
373             this.m_impl = fn;
374         }
375 
376 //        pragma(inline, true) int ref_()/+ noexcept+/ { return m_ref.ref_(); }
377 /*        pragma(inline, true) void destroyIfLastRef()/+ noexcept+/
378         { if (!m_ref.deref()) m_impl(Operation.Destroy, &this, null, null, null); }
379 */
380         pragma(inline, true) bool compare(void** a) { bool ret = false; m_impl(Operation.Compare, &this, null, a, &ret); return ret; }
381         /+ inline void call(QObject *r, void **a)  { m_impl(Call,    this, r, a, nullptr); } +/
382     protected:
383         ~this() {}
384     private:
385         /+ Q_DISABLE_COPY_MOVE(QSlotObjectBase) +/
386 @disable this(this);
387 /+this(ref const(QSlotObjectBase));+//+ref QSlotObjectBase operator =(ref const(QSlotObjectBase));+/    }
388 
389     // implementation of QSlotObjectBase for which the slot is a pointer to member function of a QObject
390     // Args and R are the List of arguments and the return type of the signal to which the slot is connected.
391     /+ template<typename Func, typename Args, typename R> class QSlotObject : public QSlotObjectBase
392     {
393         typedef QtPrivate::FunctionPointer<Func> FuncType;
394         Func function;
395         static void impl(int which, QSlotObjectBase *this_, QObject *r, void **a, bool *ret)
396         {
397             switch (which) {
398             case Destroy:
399                 delete static_cast<QSlotObject*>(this_);
400                 break;
401             case Call:
402                 FuncType::template call<Args, R>(static_cast<QSlotObject*>(this_)->function, static_cast<typename FuncType::Object *>(r), a);
403                 break;
404             case Compare:
405                 *ret = *reinterpret_cast<Func *>(a) == static_cast<QSlotObject*>(this_)->function;
406                 break;
407             case NumOperations: ;
408             }
409         }
410     public:
411         explicit QSlotObject(Func f) : QSlotObjectBase(&impl), function(f) {}
412     };
413     // implementation of QSlotObjectBase for which the slot is a functor (or lambda)
414     // N is the number of arguments
415     // Args and R are the List of arguments and the return type of the signal to which the slot is connected.
416     template<typename Func, int N, typename Args, typename R> class QFunctorSlotObject : public QSlotObjectBase
417     {
418         typedef QtPrivate::Functor<Func, N> FuncType;
419         Func function;
420         static void impl(int which, QSlotObjectBase *this_, QObject *r, void **a, bool *ret)
421         {
422             switch (which) {
423             case Destroy:
424                 delete static_cast<QFunctorSlotObject*>(this_);
425                 break;
426             case Call:
427                 FuncType::template call<Args, R>(static_cast<QFunctorSlotObject*>(this_)->function, r, a);
428                 break;
429             case Compare: // not implemented
430             case NumOperations:
431                 Q_UNUSED(ret);
432             }
433         }
434     public:
435         explicit QFunctorSlotObject(Func f) : QSlotObjectBase(&impl), function(std::move(f)) {}
436     };
437 
438     // typedefs for readability for when there are no parameters
439     template <typename Func>
440     using QSlotObjectWithNoArgs = QSlotObject<Func,
441                                               QtPrivate::List<>,
442                                               typename QtPrivate::FunctionPointer<Func>::ReturnType>;
443 
444     template <typename Func, typename R>
445     using QFunctorSlotObjectWithNoArgs = QFunctorSlotObject<Func, 0, QtPrivate::List<>, R>;
446 
447     template <typename Func>
448     using QFunctorSlotObjectWithNoArgsImplicitReturn = QFunctorSlotObjectWithNoArgs<Func, typename QtPrivate::FunctionPointer<Func>::ReturnType>; +/
449 }
450 
451 extern(D) struct DQtStaticSlotObject(Params...)
452 {
453     QSlotObjectBase base;
454     alias Dg = void delegate(Params);
455     Dg dg;
456 
457     extern(C++) static void impl(int which, QSlotObjectBase *this_, QObject r, void **a, bool *ret)
458     {
459         import core.stdcpp.new_;
460         switch (which) {
461         case QSlotObjectBase.Operation.Destroy:
462             cpp_delete(cast(DQtStaticSlotObject*)(this_));
463             break;
464         case QSlotObjectBase.Operation.Call:
465             (cast(DQtStaticSlotObject*)(this_)).dg();
466             break;
467         case QSlotObjectBase.Operation.Compare: // not implemented
468         case QSlotObjectBase.Operation.NumOperations:
469             //Q_UNUSED(ret);
470         default:
471         }
472     }
473 public:
474     this(Dg dg)
475     {
476         base = QSlotObjectBase(&impl);
477         this.dg = dg;
478     }
479 }
480 
481 extern(D) struct DQtMemberSlotObject(T, alias F, Params...) if(is(T: QObject))
482 {
483     QSlotObjectBase base;
484 
485     /* Need to use a custom mangling, because the template parameters
486      * may not have a C++ mangling. */
487     pragma(mangle, DQtMemberSlotObject.mangleof ~ "__impl")
488     extern(C++) static void impl(int which, QSlotObjectBase *this_, QObject r, void **a, bool *ret)
489     {
490         import core.stdcpp.new_;
491         import std.traits;
492         switch (which) {
493         case QSlotObjectBase.Operation.Destroy:
494             cpp_delete(cast(DQtMemberSlotObject*)(this_));
495             break;
496         case QSlotObjectBase.Operation.Call:
497             mixin("extern(" ~ functionLinkage!F ~ ") ReturnType!F delegate(Parameters!F) dg;");
498             dg.ptr = cast(void*)r;
499             dg.funcptr = &F;
500             mixin((){
501                 import std.conv;
502                 string r;
503                 r = "dg(";
504                 foreach(i; 0..Params.length)
505                 {
506                     r ~= text("*cast(Params[", i, "]*)a[", i + 1, "], ");
507                 }
508                 r ~= ");";
509                 return r;
510                 }());
511             break;
512         case QSlotObjectBase.Operation.Compare: // not implemented
513         case QSlotObjectBase.Operation.NumOperations:
514             //Q_UNUSED(ret);
515         default:
516         }
517     }
518 public:
519     @disable this();
520     this(int dummy)
521     {
522         base = QSlotObjectBase(&impl);
523     }
524 }