There is a better way to do this as of Ruby 2.7, which is Module.const_source_location. > Admin.const_source_location(:LIMIT) #=> [“SOME_PATH/user.rb”, 2] References: Ruby 2.7 adds Module#const_source_location ruby-core.doc Bonus from @ulysse-bn: To have a quick access to this method, you can add it to IRB config like this: ~/.irbrc # displays path of constant # # Usage: … Read more
It’s because const implies internal linkage by default, so your “definition” isn’t visible outside of the translation unit where it appears. In this case, by far the best solution is to put the declaration (extern int const n;) in a header file, and include that in both a.cpp and b.cpp. The linkage is determined by … Read more
Edit Sep 2022: With Typescript 4.9 we can now use satisfies operator: type MyType = { name: string } const x ={ name: ‘test’, // Autocompleted, typesafe } as const satisfies MyType x.name // type is ‘test’ (not string) And if for some reason, you can’t use satisfies, it’s fairly easy to replicate the same … Read more
void myfunc(const char x); This means that the parameter x is a char whose value cannot be changed inside the function. For example: void myfunc(const char x) { char y = x; // OK x = y; // failure – x is `const` } For the last one: int myfunc() const; This is illegal unless … Read more
In ECMAScript 6 you can use computed values for object keys: var CONSTANT_A = 0, CONSTANT_B = 1 var state_machine = { [CONSTANT_A]: function () { return ‘a’ }, [CONSTANT_B]: function () { return ‘b’ } }; console.log(state_machine) This does not work in Internet Explorer 11 nor in Safari browsers: https://kangax.github.io/compat-table/es6/#test-object_literal_extensions_computed_properties
Flaws Your proposed solution is not safe in a way you want it to be. One can use untyped integer constants to create new values of unary having a different int value than 1 or -1. See this example: p := unary.Positive fmt.Printf(“%v %d\n”, p, p) p = 3 fmt.Printf(“%v %d\n”, p, p) Output will … Read more
Usually you should prefer std::string over plain char pointers. Here, however, the char pointer initialized with the string literal has a significant benefit. There are two initializations for static data. The one is called static initialization, and the other is called dynamic initialization. For those objects that are initialized with constant expressions and that are … Read more
YES you can but only for int types. If you want your static member to be any other type, you’ll have to define it somewhere in a cpp file. class A{ private: static const int a = 4; // valid static const std::string t ; // can’t be initialized here … … }; // in … Read more
const is pointless when the argument is passed by value since you will not be modifying the caller’s object. Wrong. It’s about self-documenting your code and your assumptions. If your code has many people working on it and your functions are non-trivial then you should mark const any and everything that you can. When writing … Read more
Anywhere in one compilation unit (usually a .cpp file) would do: foo.h class foo { static const string s; // Can never be initialized here. static const char* cs; // Same with C strings. static const int i = 3; // Integral types can be initialized here (*)… static const int j; // … OR … Read more