proxy-pattern | 易学教程

How do the Proxy, Decorator, Adapter, and Bridge Patterns differ?

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问题 I was looking at the Proxy Pattern, and to me it seems an awful lot like the Decorator, Adapter, and Bridge patterns. Am I misunderstanding something? What's the difference? Why would I use the Proxy pattern versus the others? How have you used them in the past in real world projects? 回答1: Proxy, Decorator, Adapter, and Bridge are all variations on "wrapping" a class. But their uses are different. Proxy could be used when you want to lazy-instantiate an object, or hide the fact that you're

Proxy pattern in Python

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问题 I have a lots of class implemented in my code. Now I realise that for each method invoked for all these classes I need to add a line: with service as object: So I'm trying to use the Proxy pattern to automatically do the job, this is my example code class A(object): def __init__(self, name): self.name = name def hello(self): print 'hello %s!' % (self.name) def __enter__(self): print 'Enter the function' return self def __exit__(self, exc_type, exc_value, traceback): print 'Exit the function'

mixing constructor and apply traps on the Javascript Proxy object

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问题 I have a class that I'd like to apply a proxy to, observing method calls and constructor calls: Calculator.js class Calc { constructor(){} add(a, b) { return a+b; } minus(a, b) { return a-b; } } module.exports = Calc; index.js const Calculator = require('./src/Calculator'); const CalculatorLogger = { construct: function(target, args, newTarget) { console.log('Object instantiated'); return new target(...args); }, apply: function(target, thisArg, argumentsList) { console.log('Method called'); }

How to create a dynamic proxy in Kotlin common code?

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问题 If I'm on the JVM I can do this: object Playground { class DynamicInvocationHandler : InvocationHandler { @Throws(Throwable::class) override operator fun invoke(proxy: Any, method: Method, args: Array<Any>): Any { LOGGER.info("Invoked method: {}", method.name) return 42 } companion object { private val LOGGER = LoggerFactory.getLogger( DynamicInvocationHandler::class.java) } } @JvmStatic fun main(args: Array<String>) { val proxy = Proxy.newProxyInstance( Playground::class.java.classLoader,

Javascript Proxy and spread syntax, combined with console.log

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问题 So, I was playing around with Proxy objects and while trying to see how they mix with spread syntax and de-structuring, I stubled upon this weird behavior: const obj = { origAttr: 'hi' } const handler = { get(target, prop) { console.log(prop); return 1; }, has(target, prop) { return true; }, ownKeys(target) { return [...Reflect.ownKeys(target), 'a', 'b']; }, getOwnPropertyDescriptor(target, key) { return { enumerable: true, configurable: true }; } } const test = new Proxy(obj, handler); const

Python proxy class

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问题 I'm trying to create a Proxy class to another class. I want this class to be passed into the proxy in its constructor and then for the proxy to dynamically create all the same methods of this class on itself. This is what I hvae so far which is not working: import inspect from optparse import OptionParser class MyClass: def func1(self): print 'MyClass.func1' def func2(self): print 'MyClass.func1' class ProxyClass: def __init__(self): myClass = MyClass() members = inspect.getmembers(MyClass,

How to exactly work the Spring Inheritance-based Proxies configuration?

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问题 I am studying for the Spring Core certification and I am finding some doubts related to the proxying notion. So on the study material I find the following quiz: There is a Java configuration class that contains the following methods: @Bean public AccountRepository accountRepository(){ return new JdbcAccountRepository(); } @Bean public TransferService transferService1() { TransferServiceImpl service = new TransferServiceImpl(); service.setAccountRepository(accountRepository()); return service;

If In Proxy Pattern we have interface instead of actual concrete Subject in Proxy class is it equivalent to Decorator Pattern

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问题 Proxy pattern delegates the request to the Real subject after doing some additional processing like applying checks if request needs to be processed or not based on may be some credential checks. It has class diagram as below Proxy class has a direct reference to the concrete Subject. Decorator Pattern enriches the behavior of the component [like proxy it also does some additional processing and delegates the operation to the real component]. The class diagram of this pattern is similar to

How to create a dynamic proxy in Kotlin common code?

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If I'm on the JVM I can do this: object Playground { class DynamicInvocationHandler : InvocationHandler { @Throws(Throwable::class) override operator fun invoke(proxy: Any, method: Method, args: Array<Any>): Any { LOGGER.info("Invoked method: {}", method.name) return 42 } companion object { private val LOGGER = LoggerFactory.getLogger( DynamicInvocationHandler::class.java) } } @JvmStatic fun main(args: Array<String>) { val proxy = Proxy.newProxyInstance( Playground::class.java.classLoader, arrayOf<Class<*>>(MutableMap::class.java), DynamicInvocationHandler()) as MutableMap<String, String>

Python proxy class

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I'm trying to create a Proxy class to another class. I want this class to be passed into the proxy in its constructor and then for the proxy to dynamically create all the same methods of this class on itself. This is what I hvae so far which is not working: import inspect from optparse import OptionParser class MyClass: def func1(self): print 'MyClass.func1' def func2(self): print 'MyClass.func1' class ProxyClass: def __init__(self): myClass = MyClass() members = inspect.getmembers(MyClass, predicate=inspect.ismethod) for member in members: funcName = member[0] def fn(self): print 'ProxyClass.