The first question is why you need to serialize the static members? Static members are associated with the class, not the instances, so it does not make sense to include them when serializing an instance. The first solution is to make those members not static. Or, if those members are the same in the original … Read more
The Standard requires (section 9.4.2): A static data member of literal type can be declared in the class definition with the constexpr specifier; if so, its declaration shall specify a brace-or-equal-initializer in which every initializer-clause that is an assignment-expression is a constant expression. In your “second attempt” and the code in Ilya’s answer, the declaration … Read more
They will persist for the duration of AppDomain. Changes done to static variable are visible across methods. MSDN: If a local variable is declared with the Static keyword, its lifetime is longer than the execution time of the procedure in which it is declared. If the procedure is inside a module, the static variable survives … Read more
Consider: template<typename T, T> struct value { }; template<typename T> struct HasStatics { static int a; // we force this to be initialized typedef value<int&, a> value_user; }; template<typename T> int HasStatics<T>::a = /* whatever side-effect you want */ 0; It’s also possible without introducing any member: template<typename T, T> struct var { enum { … Read more
While the exact details of the type system are implementation dependent, let me go into some more detail than just stating that it depends and you should not care. I’ll describe how it approximately works in Microsoft’s implementation (.NET) according to the book CLR via C# by Jeffrey Richter and the article See How the … Read more
TL;DR: Your example is well-defined. Merely dereferencing a null pointer is not invoking UB. There is a lot of debate over this topic, which basically boils down to whether indirection through a null pointer is itself UB. The only questionable thing that happens in your example is the evaluation of the object expression. In particular, … Read more
This was discussed on usenet some time ago, while i was trying to answer another question on stackoverflow: Point of Instantiation of Static Data Members. I think it’s worth reducing the test-case, and considering each scenario in isolation, so let’s look at it more general first: struct C { C(int n) { printf(“%d\n”, n); } … Read more
No, static members are associated with the Type, which is associated with the AppDomain it’s loaded in. Note that there doesn’t have to be any instances of HasStatic for the class to be initialized and the shared variable to have a reference to a List<string>. Unless you’re considering situations where AppDomains get unloaded, static variables … Read more
Your methods are missing the static keyword. Change function getInstanceByName($name=””){ to public static function getInstanceByName($name=””){ if you want to call them statically. Note that static methods (and Singletons) are death to testability. Also note that you are doing way too much work in the constructor, especially all that querying shouldn’t be in there. All your … Read more
PHP can’t parse non-trivial expressions in initializers. I prefer to work around this by adding code right after definition of the class: class Foo { static $bar; } Foo::$bar = array(…); or class Foo { private static $bar; static function init() { self::$bar = array(…); } } Foo::init(); PHP 5.6 can handle some expressions now. … Read more