RTTI in Error Handling
How can I use RTTI to implement a robust error handling system that provides detailed type information?
Using RTTI to implement a robust error handling system can provide detailed type information, making debugging and error tracking more effective.
Here's an approach to create such a system. First, create a base Exception class:
#include <stdexcept>
#include <string>
#include <typeinfo>
class Exception : public std::runtime_error {
public:
Exception(const std::string& message)
: std::runtime_error(message) {}
virtual std::string getTypeName() const {
return typeid(*this).name();
}
};Implement specific exception types:
#include <stdexcept>
#include <string>
#include <typeinfo>
class Exception : public std::runtime_error {/*...*/};
class NetworkException : public Exception {
public:
NetworkException(const std::string& message)
: Exception(message) {}
};
class DatabaseException : public Exception {
public:
DatabaseException(const std::string& message)
: Exception(message) {}
};Create an error handling function that uses RTTI:
#include <iostream>
#include <stdexcept>
#include <string>
#include <typeinfo>
class Exception : public std::runtime_error {/*...*/};
class NetworkException : public Exception {/*...*/};
class DatabaseException : public Exception {/*...*/};
void handleException(const Exception& e) {
std::cout << "Exception type: "
<< e.getTypeName() << '\n';
std::cout << "Error message: "
<< e.what() << '\n';
if (typeid(e) == typeid(NetworkException)) {
std::cout
<< "Network-specific error handling...\n";
} else if (typeid(e) == typeid(DatabaseException)) {
std::cout
<< "Database-specific error handling...\n";
} else {
std::cout
<< "Generic error handling...\n";
}
}Use the error handling system:
#include <iostream>
#include <stdexcept>
#include <string>
#include <typeinfo>
class Exception : public std::runtime_error {/*...*/};
class NetworkException : public Exception {/*...*/};
class DatabaseException : public Exception {/*...*/};
void handleException(Exception&) {/*...*/}
void simulateError(int errorType) {
if (errorType == 1) {
throw NetworkException("Connection failed");
} else if (errorType == 2) {
throw DatabaseException("Query execution failed");
} else {
throw Exception("Unknown error");
}
}
int main() {
for (int i = 0; i < 3; ++i) {
try {
simulateError(i);
} catch (const Exception& e) {
handleException(e);
std::cout << "-------------------\n";
}
}
}Exception type: class Exception
Error message: Unknown error
Generic error handling...
-------------------
Exception type: class NetworkException
Error message: Connection failed
Network-specific error handling...
-------------------
Exception type: class DatabaseException
Error message: Query execution failed
Database-specific error handling...
-------------------This system provides several benefits:
- Detailed type information: The
getTypeName()method uses RTTI to provide the exact type of the exception. - Type-specific handling: The
handleException()function usestypeidto perform type-specific error handling. - Extensibility: New exception types can be easily added by deriving from
Exception. - Hierarchical error handling: You can catch specific exceptions or base class exceptions as needed.
To make this system even more robust, you could:
- Add stack trace information to exceptions.
- Implement logging of exceptions with their type information.
- Create a factory for exceptions that registers them in a central registry, similar to the reflection system discussed earlier.
Remember that while RTTI provides powerful capabilities, it does come with a small runtime cost. In most cases, this cost is negligible compared to the benefits of detailed error information, but it's something to keep in mind for performance-critical systems.
Run Time Type Information (RTTI) and typeid()
Learn to identify and react to object types at runtime using RTTI, dynamic casting and the typeid() operator