What is a Wrapper?
A wrapper is a design pattern used in object-oriented programming to extend or modify the functionality of an object at runtime. It involves creating a new class that \"wraps\" around an existing class and adds new behavior or modifies the behavior of the original class. The wrapper class exposes the same interface as the original class and forwards calls to the underlying object. Wrappers are useful for adding functionality without modifying existing code.How to Implement a Wrapper?
To create a wrapper, we start by defining an interface that both the original class and the wrapper class implement. The wrapper class then holds a reference to the original class and implements the same interface. It can add new methods or modify existing ones by overriding them and calling the corresponding methods of the original class. When a client requests an operation, it can instantiate either the original class or the wrapper class and rely on the same interface to interact with both.When to Use a Wrapper?
There are many scenarios where a wrapper can be useful. Some examples include: - Caching: A wrapper can intercept calls to an object and cache the results, so subsequent calls can retrieve the data faster. This is especially useful when the original object performs expensive computations. - Logging: A wrapper can log the input and output of methods in an object, allowing for debugging and auditing purposes. - Security: A wrapper can restrict access to certain methods or data of an object, enforcing security policies. - Instrumentation: A wrapper can add new functionality to an object, like profiling or monitoring. In general, a wrapper should be used when we need to add behavior to an object that wasn't originally designed for that purpose. It is a way to achieve extensibility and modularity in a complex system. In conclusion, a wrapper is a powerful tool in the developer's toolbox. It allows us to add functionality to an object without modifying its original code, providing a way to extend and customize the behavior of an application. By implementing a wrapper, we can improve performance, add security, and enhance the user experience of our software.