Is it legal (and moral) for a member function to say delete this
?
As long as you’re careful, it’s okay (not evil) for an object to commit suicide (delete
this
).
Here’s how I define “careful”:
- You must be absolutely 100% positively sure that
this
object was allocated vianew
(not bynew[]
, nor by , nor a local object on the stack, nor a namespace-scope / global, nor a member of another object; but by plain ordinarynew
). - You must be absolutely 100% positively sure that your member function will be the last member function invoked on
this
object. - You must be absolutely 100% positively sure that the rest of your member function (after the
delete
this
line) doesn’t touch any piece ofthis
object (including calling any other member functions or touching any data members). This includes code that will run in destructors for any objects allocated on the stack that are still alive. - You must be absolutely 100% positively sure that no one even touches the
this
pointer itself after thedelete
this
line. In other words, you must not examine it, compare it with another pointer, compare it withnullptr
, print it, cast it, do anything with it.
Naturally the usual caveats apply in cases where your this
pointer is a pointer to a base class when you don’t have a .
如果在析构函数中调用delete this,则会陷入死循环:
class TDel{public: TDel() { x = 1; } virtual ~TDel() { printf("This is Dstr\n"); printf("delete this now\n"); delete this; }private: int x;};int main(){ TDel *td = new TDel; delete td;}
结果如下:
This is Dstrdelete this nowThis is Dstrdelete this nowThis is Dstrdelete this nowThis is Dstrdelete this nowThis is Dstrdelete this now...
https://isocpp.org/wiki/faq/freestore-mgmt#delete-this