理清了现代 C++ 中模板的地位。其中用 constexpr function 替代模板进行编译期计算可以说是现代 C++ 最重要的改进之一了。 constexpr 本身其实并不难以理解,非常直观。但是由于几乎每个 C++ 版本都在改进它,所以不同的 C++ 版本可以使用的内容差别很大,有时候可能给人一种inconsistency的感觉。
我们通过在constexpr构造函数声明之前加上关键字constexpr来定义它: // 字面值类类型classDebug{public:constexprDebug(boolb=true):hw(b),io(b),other(b){}constexprDebug(boolh,booli,boolo):hw(h),io(i),other(o){}constexprboolany()const{returnhw||io||other;}// must have a const member fu...
/* We can see a FIELD_DECL in a pointer-to-member expression. */ case FIELD_DECL: case PARM_DECL: case USING_DECL: return true; case AGGR_INIT_EXPR: case CALL_EXPR: /* -- an invocation of a function other than a constexpr function or a constexpr constructor. */ { tree fun = ...
/* We can see a FIELD_DECL in a pointer-to-member expression. */ case FIELD_DECL: case PARM_DECL: case USING_DECL: return true; case AGGR_INIT_EXPR: case CALL_EXPR: /* -- an invocation of a function other than a constexpr function or a constexpr constructor. */ { tree fun = ...
https://stackoverflow.com/questions/56469764/literal-class-type-member-function-constraints https://www.kdab.com/kdab-contributions-to-qt-5-0-part-4/ https://stackoverflow.com/questions/14307996/when-should-literal-classes-be-used-in-c
constexpr函数是能够在编译时期计算返回值的函数。如果函数的所有参数都是编译时常量，并且函数体内的计算...
constexpr修饰函数时表示该函数的返回值有可能是const expression。后置const修饰的成员函数表示该函数隐含...
Is it possible to initialize constexpr std::array member in a programtic way 3 Initialization of std::array with function pointer member function of constexpr object 1 Initialize constexpr array with template functions 1 How can I initialise a constexpr array with values using...
This is just a word of caution. C++14 will not be backwards compatible with C++11 in one aspect of constexpr functions. In C++11, when you define a constexpr member function, it implicitly obtains a const qualifier: The first declaration of function get
When a nonstatic member function that is not a constructor is declared with theconstexprspecifier, that member function is constant, and theconstexprspecifier has no other effect on the function type. The class of which that function is a member must be a literal type. ...