┌─────────────────────────────────┐
│ IStorage │
├─────────────────────────────────┤
│ + saveRecord(data): bool = 0 │ ◄── Pure Virtual Contract
│ + readRecord(id): string = 0 │
└────────────────┬────────────────┘
│
┌─────────┴─────────┐
▼ ▼
┌──────────────┐ ┌──────────────┐
│ SqlStorage │ │ RedisStorage │
└──────────────┘ └──────────────┘Useful for providing default cleanup logic in a pure virtual base destructor (virtual ~Base() = 0;).
#include <iostream>
#include <memory>
#include <vector>
// Abstract Base Class / Interface
class IPaymentGateway {
public:
virtual ~IPaymentGateway() = default;
// Pure Virtual Function
virtual bool processPayment(double amount) = 0;
};
class StripeGateway : public IPaymentGateway {
public:
bool processPayment(double amount) override {
std::cout << "[Stripe API] Successfully charged $" << amount << "\n";
return true;
}
};
class PayPalGateway : public IPaymentGateway {
public:
bool processPayment(double amount) override {
std::cout << "[PayPal API] Successfully routed $" << amount << "\n";
return true;
}
};
int main() {
std::vector<std::unique_ptr<IPaymentGateway>> gateways;
gateways.push_back(std::make_unique<StripeGateway>());
gateways.push_back(std::make_unique<PayPalGateway>());
for (const auto& gw : gateways) {
gw->processPayment(49.99);
}
return 0;
}virtual ~Interface() = default;) on all interface classes.override to ensure exact signature matching.