#ifndef DOXYGEN
Exec(Exec const&) = delete;
Exec& operator=(Exec const&) = delete;
-#endif
friend ExecSeq;
friend ExecPar;
friend XBT_PUBLIC void intrusive_ptr_release(Exec* e);
friend XBT_PUBLIC void intrusive_ptr_add_ref(Exec* e);
+#endif
static xbt::signal<void(Actor const&)> on_start;
static xbt::signal<void(Actor const&)> on_completion;