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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