//: C01:Cleanup.cpp // Exceptions clean up complete objects only. #include <iostream> using namespace std; class Trace { static int counter; int objid; public: Trace() { objid = counter++; cout << "constructing Trace #" << objid << endl; if(objid == 3) throw 3; } ~Trace() { cout << "destructing Trace #" << objid << endl; } }; int Trace::counter = 0; int main() { try { Trace n1; // Throws exception: Trace array[5]; Trace n2; // Won't get here. } catch(int i) { cout << "caught " << i << endl; } } ///:~
Listado 2.7. C01/Cleanup.cpp
constructing Trace #0 constructing Trace #1 constructing Trace #2 constructing Trace #3 destructing Trace #2 destructing Trace #1 destructing Trace #0 caught 3
//: C01:Rawp.cpp // Naked pointers. #include <iostream> #include <cstddef> using namespace std; class Cat { public: Cat() { cout << "Cat()" << endl; } ~Cat() { cout << "~Cat()" << endl; } }; class Dog { public: void* operator new(size_t sz) { cout << "allocating a Dog" << endl; throw 47; } void operator delete(void* p) { cout << "deallocating a Dog" << endl; ::operator delete(p); } }; class UseResources { Cat* bp; Dog* op; public: UseResources(int count = 1) { cout << "UseResources()" << endl; bp = new Cat[count]; op = new Dog; } ~UseResources() { cout << "~UseResources()" << endl; delete [] bp; // Array delete delete op; } }; int main() { try { UseResources ur(3); } catch(int) { cout << "inside handler" << endl; } } ///:~
Listado 2.8. C01/Rawp.cpp
UseResources() Cat() Cat() Cat() allocating a Dog inside handler