显式模板实例化-什么时候使用？ [英] Explicit template instantiation - when is it used?

问题描述

休息几周后，我正尝试通过 Templates–一书扩展和扩展我的模板知识。 David Vandevoorde和Nicolai M. Josuttis撰写的《完整指南》，我现在想理解的是模板的显式实例化。

After few weeks break, I'm trying to expand and extend my knowlege of templates with the book Templates – The Complete Guide by David Vandevoorde and Nicolai M. Josuttis, and what I'm trying to understand at this moment is explicit instantiation of templates.

这样的机制实际上并没有问题，但是我无法想象我想要或想要使用此功能的情况。如果有人可以向我解释，我将不胜感激。

I don't actually have a problem with the mechanism as such, but I can't imagine a situation in which I would like or want to use this feature. If anyone can explain that to me I will be more than grateful.

推荐答案

直接从 https://docs.microsoft.com/en-us/cpp/cpp/explicit-instantiation ：

您可以使用显式实例化来创建模板化类或函数的实例化，而无需在代码中实际使用它。因为在创建使用模板进行分发的库（.lib）文件时有用，所以未实例化的模板定义不会放入目标（.obj）文件中。

You can use explicit instantiation to create an instantiation of a templated class or function without actually using it in your code. Because this is useful when you are creating library (.lib) files that use templates for distribution, uninstantiated template definitions are not put into object (.obj) files.

（例如，libstdc ++包含 std :: basic_string< char，char_traits< char>，allocator< char>> （即 std :: string ），因此每次使用 std :: string 的功能时，不需要将相同的功能代码复制到对象。编译器只需要将它们引用（链接）到libstdc ++。）

(For instance, libstdc++ contains the explicit instantiation of std::basic_string<char,char_traits<char>,allocator<char> > (which is std::string) so every time you use functions of std::string, the same function code doesn't need to be copied to objects. The compiler only need to refer (link) those to libstdc++.)

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