compile-time

By an abstract class I mean the class with at least one pure virtual method. I want the compilation to fail, if the check shows that the class is not abstract. Is it even possible? Use std::is_abstract . #include <type_traits> static_assert(std::is_abstract<T>(), "T ought to be abstract."); See it in action . 来源： https://stackoverflow.com/questions/21369036/how-to-check-if-the-class-is-abstract-at-compile-time

I had nested partially specialized template code working with VS 2015 until I discovered that it was not standards-compliant . I want it to be so I twisted my code to overcome the former issue and also that one and have now hit a hard wall. Using variadic templates and partial specialization I would like to fill an array at compile-time given a fixed set of parameters. What I want to achieve also seems similar to this answer but I did not manage to make it work. Consider the following program: #include <cstdlib> template <typename T, std::size_t Size> struct Array; template <typename T, std:

Delphi - can I write my own compile-time functions for const and var declarations, executable at compiler time. Standard Delphi lib contain routines like Ord(), Chr(), Trunc(), Round(), High() etc, used for constant initialization. Can I write my own, to execute routine at compile-time and use the result as constant? Johan You cannot write your own intrinsic functions. Because that requires compiler magic. However there may be other options to achieve your goal. Preprocessor The only way is to use a preprocessor. There are several: http://wiki.delphi-jedi.org/wiki/JEDI_Pre_Processor The Delphi

Is it possible to sort elements at compile time in C? Syntax is of secondary importance, I was thinking of a macro like this: SORT(9, -1, 12, 4) // expands to: -1, 4, 9, 12 SORT(dog, cat, cow) // expands to: cat, cow, dog but I won't frown at any API as long as it sorts without issuing a single CPU instruction. The requirements are pretty lax: Pure C, no C++ . Staying within the C standard would be nice but established language extensions are fair game. Compiler is the only tool allowed . Unix sort or home-brewed code generators are not welcome as they complicate the build step. Any element

I want to compare meta programming and use of constexpr in c++0x. then I write a fib function in both model. when I use meta programming model, answer print out very fast because it calculated in compile time. but when I use constexpr funcion it calculate value in run time, not in compile time. I using g++( gcc ) 4.8 .can any body help me? #include <iostream> using namespace std; #define NUM 42 template <unsigned int N> struct Fibonacci { enum { value = Fibonacci<N - 1>::value + Fibonacci<N - 2>::value }; }; template <> struct Fibonacci<1> { enum { value = 1 }; }; template <> struct Fibonacci

I have referred many questions in SO on this topic, but couldn't find any solution so far. One natural solution was mentioned here: Determining endianness at compile time . However, the related problems mentioned in the comments & the same answer. With some modifications, I am able to compile a similar solution with g++ & clang++ ( -std=c++11 ) without any warning. static_assert(sizeof(char) == 1, "sizeof(char) != 1"); union U1 { int i; char c[sizeof(int)]; }; union U2 { char c[sizeof(int)]; int i; }; constexpr U1 u1 = {1}; constexpr U2 u2 = {{1}}; constexpr bool IsLittleEndian () { return u1

I want to enforce (compile time) array with 5 elements of a particular type I couldn't find a solution so resorted to a workaround by creating a tuple (This is abusive I know) typealias FiveElementArray = (MyType,MyType,MyType,MyType,MyType) // mock array by using typed tuple It works for my needs - until I need to access an element by index at runtime. For instance: var DB = FiveElementArray // the tuple of 5 elements tableView(tableView : UITableView,cellForRowAtIndexPath:indexPath) -> UITableViewCell { // would like to populate with the value at index DB[indexpath.row] // no such syntax for