为模块化类的实例分配唯一的数字标识符 [英] Assigning Unique Numerical Identifiers to Instances of a Templated Class

问题描述

核心问题：
我想要能够接受一个模板类的实例，例如：

Core problem: I want to be able to take an instance of a templated class, say:

template<class a, class b, class c> class foo;

foo<int, float, double>;

然后执行以下操作：

foo<int, float, double>::value;  //Evaluates to a unique number
foo<long, float, double>::value; //Evaluates to a different unique number
foo<int, float, double>::value;  //Evaulates to the same unique number

除非，真的是：

template<class a, class b, class c>
int getUniqueIdentifier()
{
    return foo<a, b, c>::value;
}

当前解决方案尝试：

我想使用Boost :: MPL的可扩展关联序列，因为每个元素都有它自己的唯一标识符，但我想我需要能够改变序列的位置，插入不做。 >
我可能正在咆哮错误的树。 （在正侧，dayum，但MPL！）

Current Solution Attempt:
I'm thinking I want to use Boost::MPL's "Extensible Associative Sequence", since each element gets it's own unique identifier, but I think I need to be able to alter the sequence in place, which "insert" doesn't do.
I may be barking up the wrong tree. (On the plus side, dayum, but MPL!)

目的：

重新发明信号插座系统。组件使用交换机来创建和注册信道，这将使用唯一标识符将信道放在映射中，从而允许运行时通用性。我尝试查找Qt库作为例子，但我不能解析他们的缩写，我想我缺少一些正式的技术诀窍。

Purpose:
Reinventing the wheel on a Signals & Sockets system. Components make and register channels with a "switchboard", which would use the unique identifiers to put the channels in a map, allowing run-time versatility. I've tried looking up the Qt library as an example, but I can't parse their abbreviations, and I think I'm missing some formal know-how.

谢谢！

推荐答案

如果你想把东西放在一个地图上，需要一个按类型的键，使用 std :: type_info :: before（）。可能值得派生一个类，以便您可以提供运算符<，或者换行 std :: type_info :: before（）在二进制谓词中。

If you want to put things in a map, and need a per-type key, the proper solution is to use std::type_info::before(). It may be worthwhile to derive a class so you can provide operator<, alternatively wrap std::type_info::before() in a binary predicate.

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