static

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 2 years ago . Improve this question I wish to create a helper class with public static methods only. I declare a class instead of namespace, because I will befriend this class with others so that it can operate on their private members as well. Is this considered a bad OOP practice? Is there an

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed last month . Improve this question I was asking my self while coding in Java, does the import static com.example.method is a good the to do or is it better to import the whole class. 回答1: Depends on the context, not exist an explicit rule to use in all the cases. But the most common use is

问题 I have a class called cache. It is an generic, abstract class responsible for handling the global cache for forever type extends the class. My question is, if I have a static variable under the base class, will the static variable be unique per extending type or will it be the same for all types that extend Cache. For example the interface: Cache<K, V> private static Cache<K, V> [creates a cache store on first load] static V get(K key); Then I have an implementing class: PersonCache extends

问题 I have a requirement to get the details of the current user who has been loggedIn. To get the details, we can use the SecurityContextHolder.getContext() and extract the details. According to, SecurityContextHolder, SecurityContext and Authentication Objects By default, the SecurityContextHolder uses a ThreadLocal to store these details, which means that the security context is always available to methods in the same thread of execution . Using a ThreadLocal in this way is quite safe if care

问题 I have the following code: template <typename T> class A { public: static int a; }; class B { public: static A<int> a1; static A<double> a2; }; int B::a1::a = 0; --> It gives an error "a1 is not a class, namespace, enumeration" (I am using llvm compiler in XCode. I can reproduce the problem with gcc as well.) How can I Declare/define/initialize a static member variable of template classes as static member variables of a class? 回答1: Static members are defined base on their class. a is static

问题 i want to serve static files in pyramids via request.static_url('some_file'). Due to several services, my templates got lines like: <script type="text/javascript" src="${request.static_url('dbas:static/first')}"></script> <script type="text/javascript" src="${request.static_url('websocket:static/second')}"></script> But unfortunately the method static_url() only delivers links with http as url_scheme, but i want https . How can I achieve this? Thanks! 回答1: Easy, you only need to specify the

问题 Can anybody who may have any idea compiling Qt 5.8 Open Source statically with PostgreSQL support on Windows. I tried all the options known to me including the below. I'm using qt 5.8 sources on Windows 10 x64. configure -opensource -confirm-license -debug-and-release -static -platform win32-msvc2015 -nomake examples -nomake tests -sql-psql PSQL_LIBS="C:\PSQL\9.6\lib\libpq.lib" -I C:\PSQL\9.6\include\libpq -I C:\PSQL\9.6\include -L C:\PSQL\9.6\lib\libpq.lib After running the config above, I

问题 Say we have some external linkage using the extern keyword. I have (in class1.cpp): MyClass* myClassVar = NULL; The constructor initializes the above, and destructor deletes. Then in class2.cpp and class3.cpp there is: extern MyClass* myClassVar; These classes use myClassVar (doing the usual null checks etc). Would a Singleton be preferred? (I know globals are bad etc, and a Singleton is just syntax sugar). Is there an advantage to change the above code to the below? static Singleton&

问题 Say we have some external linkage using the extern keyword. I have (in class1.cpp): MyClass* myClassVar = NULL; The constructor initializes the above, and destructor deletes. Then in class2.cpp and class3.cpp there is: extern MyClass* myClassVar; These classes use myClassVar (doing the usual null checks etc). Would a Singleton be preferred? (I know globals are bad etc, and a Singleton is just syntax sugar). Is there an advantage to change the above code to the below? static Singleton&

问题 Look, I know static classes can't inherit or implement. The question is "what the heck is the right C# + OOP pattern to implement this?". "This" is described below: I want to define a common set of both definition and implementation for a group of classes where all but one type should be static. Namely, I want to make some arbitrary base converters where each have exactly the same four members: // Theoritical; static classes can't actually implement interface IBaseConverter { int Base { get;