static-functions

问题 I have a relatively simple question, and although there are many posts about it on Google, I cannot find a single one that simply answers the question. So the short question is "Is it acceptable to mix static and non static methods in one class?". I guess I am really asking "is it good practice to stick with one type of method", or "are there things to consider when using both". For example, If I was building a class to cope with food in my fridge, which of the following (or what else) would

问题 I have a relatively simple question, and although there are many posts about it on Google, I cannot find a single one that simply answers the question. So the short question is "Is it acceptable to mix static and non static methods in one class?". I guess I am really asking "is it good practice to stick with one type of method", or "are there things to consider when using both". For example, If I was building a class to cope with food in my fridge, which of the following (or what else) would

问题 I have a base class and a derived one and I want to change base functions while keeping them static as they should be passed to other functions as static. How can I do that? 回答1: The ATL framework gets around the limitation of no virtual statics by making the base class be a template, and then having derived classes pass their class type as a template parameter. The base class can then call derived class statics when needed, eg: template< class DerivedType > class Base { public: static void

问题 We make a non-member function a friend of a class when we want it to access that class's private members. This gives it the same access rights as a static member function would have. Both alternatives would give you a function that is not associated with any instance of that class. When must we use a friend function? When must we use a static function? If both are viable options to solve a problem, how do we weigh up their suitability? Is there one that should be preferred by default? For

问题 I am building a qt application in which i am have to access ui elements. but i am getting error as invalid use of member 'foo::ui' in static member function The code is big so cant add here. Declaration of ui private: Ui::foo *ui; Initialization in Constructor foo::foo(QWidget *parent) : QMainWindow(parent), ui(new Ui::foo) { ui->setupUi(this); } Accessing in static function where it is giving error. ui->fp->setText("Some Text"); Static function declaration. static I eventCallback(PVOID i_pv

问题 I have a C file contains some static functions, how to use google test to test those static function? header file: test.h int accessData(); source file: test.c static int value; static int getData() { return value; } int accessData() { if(value != 0) { return getData(); } return 0; } static function is called by global function, but how to test those static function using google test? 回答1: One way to achieve this is to #include the C source file into your test source. Then, the static

问题 I have a basic class that containers two enumerators, one for input and one for output. It has two member functions which are both static. The first function is just a static function that returns a value based on the input. It will call the second function which is a constexpr function template that will return the constexpr values. You can see the full class here. class Foo { public: enum Input { INPUT_0 = 0, INPUT_1, INPUT_2 }; enum Output { OUTPUT_0 = 123, OUTPUT_1 = 234, OUTPUT_2 = 345 }

问题 Is there a reason why most function definition in device driver in linux code is defined as static? Is there a reason for this? I was told this is for scoping and to prevent namespace pollution, could anyone explain it in detail why static definition is used in this context? 回答1: Functions declared static are not visible outside the translation unit they are defined in (a translation unit is basically a .c file). If a function does not need to be called from outside the file, then it should

问题 In C++, when you have local variables in a static member function, does it mean those local variables are also implicitly static or are they really local? example: static void myClass::somefunc(int someint) { int myint = someint; // is myint really a local variable or does it change due to the static qualifier at function level? } Also, different threads from a thread pool running this function, does myint need to be protected by a lock? assuming that all values passed to it are different and

问题 I'm a bit confused on how constructors work in PHP. I have a class with a constructor which gets called when I instantiate a new object. $foo = new Foo($args); __construct($params) is called in the class Foo and it executes the appropriate initialization code. However when I use the class to call a static function, the constructor is called again. $bar = Foo::some_function(); //runs the constructor from Foo This causes the constructor to execute, running the object initialization code that I