proxy-pattern

问题 Context I was trying to implement a nD array like container. Something that would wrap an underlying sequence container and allow to process it as a container of containers (of...): arr[i][j][k] should be a (eventually const) reference for _arr[(((i * dim2) + j) * dim3) + k] . Ok until there, arr[i] has just to be a wrapper class over the subarray... And when I tried to implement interators, I suddenly realized that dragons were everywhere around: my container is not a standard compliant

问题 I think this may be a case where I know the answer but just don't like it. My starting point was an earlier question, Hibernate @Entity conflict with Spring @Autowired for non-column object. I have an @Entity which is "naturally" linked in a one-to-many relationship with another set of entities. In my example, I'm calling it an ItemEntity, and it has a (very) large price history. So large, that having Hibernate lazy-load is a performance killer because real use cases never need all of the

问题 Can you give any good explanation what is the difference between Proxy and Decorator ? The main difference I see is that when we assume that Proxy uses composition and Decorator uses aggregation then it seems to be clear that by using multiple (one or more) Decorators you can modify/ add functionalities to pre-existing instance (decorate), whereas Proxy has own inner instance of proxied class and delegates to it adding some additional features (proxy behaviour). The question is - Does Proxy

问题 I was going through one of the Articles on Proxy pattern. Read the Comments After the Explanation In this article there are few downsides mentioned for Proxy Patterns, but I am not able to understand: 1) The downside here is 'magic' could be happening that an extender is unaware of (a 'black-box' problem). Please explain the magic . 2) A proxy can mask the life-cycle and state of a volatile resource from its client. A client may call the proxy not realizing that the resource is currently

问题 Suppose we have some Foo object that allows: cout << myFoo[3]; myFoo[5] = "bar"; This calls for a proxy design-pattern (detailed by Scott Meyers here) But now let us suppose every myFoo[i] is also a Foo instance. myFoo[7] = Foo{...}; myFoo[5] = "bar"; // Foo has a Foo(std::string) non-explicit constructor I'm close to having an implementation, but I can't get rid of one final pesky "forward declaration/ incomplete type" error. Firstly, let's get the easy one out of the way: // x =

问题 As I understood both Adapter and Proxy patterns make two distinct/different classes/objects compatible with each for communication. And both of them are Structural patterns. I am getting that both of them are pretty much similar with each other. Can some one explain what exactly make(s) them different? EDIT: I went through this question. But I'd rather like to have a close comparison between Adapter and Proxy. 回答1: Adapter: It allows two unrelated interfaces to work together through the

问题 Suppose I have a simple vector class where elements are accessed through a proxy class. Vector class: class vec { public: vec(int len) { length = len; data = new double [len]; } proxy operator[](int i) { if (i >= 0 && i < length) { return proxy(i, data); } else { std::cerr << "AHHHH!\n"; exit(1); } } private: int length; double * data; }; Proxy class: class proxy { public: proxy(int i, double * d) { index = i; data = d; } void operator=(double rhs) { data[index] = rhs; } private: int index;

问题 I use this code to override the window.alert function. The function replaces breaks by \r\n. It works fine in Firefox, but ofcourse not in IE. Im getting the error: Property or method not supported. (function() { var proxied = window.alert; window.alert = function(txt) { txt = txt.replace(/<br>/g, "\r\n"); return proxied.apply(this, arguments); }; })(); Please help me find the solution! Thank you 回答1: I would do this, in case window.alert is not a "real" function in IE: (function() { var

问题 I'm trying to wrap a Python PyObject* in an Object class. In Python, everything is a PyObject* . A list is a PyObject* , and each item in the list is itself a PyObject* . Which could even be another list. etc. I'm trying to allow fooList[42] = barObj style syntax by means of a Proxy pattern (here). Now that I have that working, I want to extend it so that fooList[42] can be used as an Object . Specifically I want to be able to handle... fooList[42].myObjMethod() fooList[42].myObjMember = ...

问题 I'm trying to wrap a Python PyObject* in an Object class. In Python, everything is a PyObject* . A list is a PyObject* , and each item in the list is itself a PyObject* . Which could even be another list. etc. I'm trying to allow fooList[42] = barObj style syntax by means of a Proxy pattern (here). Now that I have that working, I want to extend it so that fooList[42] can be used as an Object . Specifically I want to be able to handle... fooList[42].myObjMethod() fooList[42].myObjMember = ...