In the proxy extra functionality can be provided, for example caching when operations on the real object are resource intensive, or checking preconditions before operations on the real object are invoked. Use of the proxy can simply be forwarding to the real object, or can provide additional logic. A proxy is a wrapper or agent object that is being called by the client to access the real serving object behind the scenes. Using the proxy pattern, a class represents the functionality of another class.Ī proxy, in its most general form, is a class functioning as an interface to something else. The Door object can be replaced by the SecuredDoor and the SecuredDoor class does not introduce any new methods, it only extends the functionality of the open_method of the Door class. That requires the objects of your subclasses to behave in the same way as the objects of your superclass. Objects of a superclass shall be replaceable with objects of its subclasses without breaking the application. This conforms to the Liskov Substitution Principle.
In the case of proxy pattern, you can substitute primary object with the proxy object without any additional changes in the code. Notice how the class Door was called from SecuredDoor via composition. This method gets extended in the SecuredDoor class and in this case, I’ve just added a print statement to the method of the latter class. Here, the Door class has a single method called open_method which denotes the action of opening on the Door object. The above code snippet concretizes the example given before. > Adding security measure to the method of Let me better explain it using the code example below. The door’s main functionality is to open but there is a proxy added on top of it to add some functionality. it can be opened either using access card or by pressing a button that bypasses the security. Have you ever used an access card to go through a door? There are multiple options to open that door i.e. The Proxy Patternīefore diving into the academic definition, let’s try to understand the Proxy pattern from an example. So I thought I’d document it here for future reference. However, recently there is one design pattern that I find myself using over and over again to write more maintainable code and that is the Proxy pattern.
Instead of littering your code with seemingly over-engineered patterns, you can almost always take the advantage of Python’s first-class objects, duck-typing, monkey-patching etc to accomplish the task at hand. Python’s dynamic nature and the treatment of functions as first-class objects often make Java-ish design patterns redundant. Also, in the realm of dynamic languages, design patterns have the notoriety of injecting additional abstraction layers to the core logic and making the flow gratuitously obscure.
In Python, there’s a saying that design patterns are anti-patterns.
0 kommentar(er)
