but in typescript this.constructor.prop causes error “TS2339: Property ‘prop’ does not exist on type ‘Function’”. Typescript does not infer the type of constructor to be anything beyond Function (after all … the constructor might be a sub class). So use an assertion: class SomeClass { static prop = 123; method() { (this.constructor as typeof SomeClass).prop; … Read more
In the context of a class, static variables are on the class scope (not the object) scope, but unlike a const, their values can be changed. class ClassName { static $my_var = 10; /* defaults to public unless otherwise specified */ const MY_CONST = 5; } echo ClassName::$my_var; // returns 10 echo ClassName::MY_CONST; // returns … Read more
Clang seems to be in the right. When accessing a static member with the member access syntax [class.static/1]: A static member s of class X may be referred to using the qualified-id expression X::s; it is not necessary to use the class member access syntax to refer to a static member. A static member may … Read more
Yes, you are just lucky 🙂 The extern “C” is one language linkage for the C language that every C++ compiler has to support, beside extern “C++” which is the default. Compilers may supports other language linkages. GCC for example supports extern “Java” which allows interfacing with java code (though that’s quite cumbersome). extern “C” … Read more
With this code: class var items: [AnyObject] { return [AnyObject]() } you are not creating a stored property – instead it’s a computed property, and the worst part is that every time you access to it, a new instance of [AnyObject] is created, so whatever you add to it, it’s lost as soon as its … Read more
C++17 and above Use inline static variables for non-dynamic initialization: struct Foo { inline static int I = 0; }; And use function local static variables otherwise: struct Foo { static std::string& Bar() { static std::string S = compute(); return S; } }; C++14 and below Use function local statics, as they are plain easier … Read more
I get asked questions like this all the time. Basically the question boils down to “when a fact about a declared member can be deduced by the compiler should the explicit declaration of that fact be (1) required, (2) optional, or (3) forbidden?” There’s no one easy answer. Each one has to be taken on … Read more
In C++03 we were only allowed to provide an in class initializer for static member variables of const integral of enumeration types, in C++11 we could initialize a static member of literal type in class using constexpr. This restriction was kept in C++11 for const variables mainly for compatibility with C++03. We can see this … Read more
You cannot override static methods or fields of any type in Java. public class User extends BaseModel { static String table = “user”; //snip } This creates a new field User#table that just happens to have the same name as BaseModel#table. Most IDEs will warn you about that. If you change the value of the … Read more
Enums are great for lightweight state information. For example, your color enum (excluding blue) would be good for querying the state of a traffic light. The true color along with the whole concept of color and all its baggage (alpha, color space, etc) don’t matter, just which state is the light in. Also, changing your … Read more