编译时单例多于一次实例化检测 [英] Compile-time singleton more-than-one-time-instantiation detection

问题描述

是否可以创建一个模板元构造，该构造元可以在第一次（或前n次）调用时执行一条执行路径，而在一次以上（然后n次）调用时执行另一条执行路径？

Is it possible to create a template meta construction that can take one execution path first time (or first n times) it is called and another execution path if it is called more than once (more then n times)?

推荐答案

否。模板仅在编译时评估。

No. Templates are evaluated at compile time only.

问题在于运行时发生的事情（执行路径）。

现在应该可以在代码中构建此构造了，但它不是模板元结构（尽管它可以是模板元程序的一部分，但是进行测试的代码将是运行时代码（即普通代码）。）

The question is about things that happen at run-time (execution path).
Now it should be very possible to build this construct in code, but it is not a template meta-construct (though it can be part of a template meta-program, but the code that does the test will be runtime code (ie normal code)).

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