composition

问题 (An earlier question, Recursively (?) compose LINQ predicates into a single predicate, is similar to this but I actually asked the wrong question... the solution there satisfied the question as posed, but isn't actually what I need. They are different, though. Honest.) Given the following search text: "keyword1 keyword2 ... keywordN" I want to end up with the following SQL: SELECT [columns] FROM Customer WHERE ( Customer.Forenames LIKE '%keyword1%' OR Customer.Forenames LIKE '%keyword2%' OR .

问题 I know, somebody had asked the same question about this case, but i still don't really get it, i need a specific answer. Thank you :D 回答1: Since Gangnus did not correctly explain the meaning of composition, I'll have to do it. As explained by Gangnus, an aggregation is a special form of association with the intended meaning of a part-whole-relationship , but without a precise semantics (the UML spec says: "Precise semantics of shared aggregation varies by application area and modeler"). For

问题 So i'm not too sure how to phrase this properly, but say I wanted to get the sum of all odd numbers in a list, do I have two functions (sumList and getOddNumbers) and combine them into sumOddList or is there a way to put these two together in a single function? If there isnt a better function, how exactly would I combine them into sumOddList? getOddNumbers :: [Integer] -> [Integer] getOddNumbers [] = [] getOddNumbers (x:xs) |odd x = x:getOddNumbers xs |otherwise = getOddNumbers xs sumList ::

问题 In traditional MDI applications some objects (Forms) will be created when a command occurs (Ex. pressing a ribbon button), so it maybe a composition point. I'm confiused about composition root in such applications. I read somewhere that we can use a ViewModelLocator which looks like Service Locator pattern. As you know the service locator pattern is denounced by some people. Now please advice me about this issue. Thanks in advance. 回答1: Whether or not a ViewModelLocator is a Service Locator

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 8 years ago . The inner class is always inside the outer class. If we removed the outer class, the inner class would also be destroyed. I'm not concerned about memory release, I am only thinking about the concept. And this is

问题 For example, suppose we had the functions double(x) = 2 * x , square(x) = x ^ 2 and sum(x,y) = x + y . What is a function compose such as compose(compose(sum, square), double) = x^2 + 2*x ? Notice that I'm asking a function that can be used for functions of any arity. For example, you could compose f(x,y,z) with g(x) , h(x) , i(x) into f(g(x), h(x), i(x)) . 回答1: This is a common Haskell idiom, applicative functors: composed = f <$> g1 <*> g2 <*> ... <*> gn (A nicer introduction can be found

问题 Despite using composition over inheritance? If so, is there any solution for it at the language level? 回答1: As VonC wrote, but I'd like to point out something. The fragile base class problem is often blamed on virtual methods ( dynamic dispatch of methods – this means if methods can be overridden, the actual implementation that has to be called in case of such an overridden method can only be decided at runtime). Why is this a problem? You have a class, you add some methods to it, and if

问题 Suppose we have an object obj of type Object such that System.out.println(obj) produces {a=Some text, b=Some more text, c=Even more text} . Now we want to make a new object obj2 that is just {a=Some text} (i.e., the fields b and c are pruned from obj ). So we define a class A as follows: class A { String a; } Then we initialize obj2 as follows: A obj2 = (A) obj . Unfortunately, I get a run time error when doing this. Question: How do we define obj2 as outlined above? 回答1: Assume that you have

问题 Is it possible to extend only some specific part from multiple classes? Example: class Walker { walk() { console.log("I am walking"); } // more functions } class Runner { run() { console.log("I am running"); } // more functions } // Make a class that inherits only the run and walk functions 回答1: You can pick and choose which methods from other classes you want to add to an existing class as long as your new object has the instance data and methods that the methods you are adding expect to be

问题 In Scala, I've seen the constructs trait T extends S and trait T { this: S => used to achieve similar things (namely that the abstract methods in S must be defined before an instance may be created). What's the difference between them? Why would you use one over the other? 回答1: I'd use self-types for dependency-management: This trait requires another trait to be mixed in. And I'd use inheritance to refine another trait or interface. Just as an example: trait FooService trait FooRemoting {