V1022. Exception was thrown by pointer. Consider throwing it by value instead.
The analyzer has detected an exception thrown by pointer. A more common practice is to throw exceptions by value and catch them by reference. When thrown by pointer, an exception may never be caught as it is supposed to be caught by reference. In addition, the catching part will have to call the 'delete' operator to destroy the object created to avoid a memory leak.
Consider the following example:
throw new std::runtime_error("error");
Throwing an exception by pointer is not a mistake in itself, of course. Such exceptions can be properly caught and handled. But in practice, this is inconvenient and leads to errors. The arguments against throwing exceptions by pointer are as follows:
- You have to take care of destroying the object yourself by calling the 'delete' operator.
- You cannot use 'catch(...)' since the program does not know how to destroy the object.
- This is a non-standard way of error reporting, and other parts of the program may fail to handle such exceptions properly.
- If you have run out of dynamic memory, an attempt to create a new object using the 'new' operator may fail too.
So, throwing exceptions by pointer can be considered an anti-pattern, which should be rewritten into correct code.
- Deb Haldar. Top 15 C++ Exception handling mistakes and how to avoid them. (Mistake # 6: Not Throwing an exception by value)
- Discussion on StackOverflow. throw new std::exception vs throw std::exception.
- Discussion on StackOverflow. C++: Throwing exceptions, use 'new' or not?
- Discussion on StackOverflow. c++ exception : throwing std::string.
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You can look at examples of errors detected by the V1022 diagnostic.