![]() I'd venture that it's much more common to take advantage of template metaprogramming that someone else has done for you - eg. Template metaprogramming is potentially very powerful, but the number of cases where this example is useful and important enough for performance are tiny.īut it is a useful technique in C++ since it allows the language to do a lot of powerful tricks that would otherwise be out of reach. How big a part of C++ was I missing out on?Ī case like that, not often at all. How often do you people use this? I have been using C++ for a while now,īut never used this before. The down side to it is that it has to be calculated at compile time, so if your n is determined at runtime then you can't use that method. In some vanishingly small number of cases, that might make quite a difference. It's faster - theoretically the compiler will expand the set of templates at compile time such that Factorial::value is simply a single constant. What is the advantage of using this rather than normal runtime factorial calculation? Syntactically, template is reserved to mark an explicit template specialization, instead of a template without parameters: template ![]() But a template without any explicit argument is possible - it has default arguments: template Struct Factorial2 Ī template without any parameters is not possible. The best way to think of a template is to do something similar to what the compiler does: consider the template as a class, where you replace the template parameter with an actual value of that type.įactorial::value is equivalent to: // generated by the compiler when Factorial::value is encountered in code: You do not usually see this form as defining templates rarely uses constants in the template parameters. See Boost meta-programming library to get a hint of what can be done.Ī template declaration can be made on classes/types, on values and on pointers. Such functionality is rarely achieved using this method, but metaprogramming is used more and more nowadays. How big a part of C++ was I missing out on?
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |