How bad is “if (!this)” in a C++ member function?

Question

If I come across old code that does if (!this) return; in an app, how severe a risk is this? Is it a dangerous ticking time bomb that requires an immediate app-wide

Answer 1

If you have many GetLookup functions return NULL, then you're better off fixing code that calls methods using a NULL pointer. First, replace

if (!this) return NULL;

with

if (!this) {
  // TODO(Crashworks): Replace this case with an assertion on July, 2012, once all callers are fixed.
  printf("Please mail the following stack trace to myemailaddress. Thanks!");
  print_stacktrace();
  return NULL;
}

Now, carry on with your other work, but fix these as they roll in. Replace:

GetLookup(x)->Lookup(y)...

with

convert_to_proxy(GetLookup(x))->Lookup(y)...

Where conver_to_proxy does returns the pointer unchanged, unless it's NULL, in which case it returns a FailedLookupObject as in my other answer.