如何根据变量值惯用地调用 C++ 函数? [英] How to idiomatically call C++ functions based on variable value?

问题描述

假设我有一个数据类型 enum TreeTypes { TallTree, ShortTree, MediumTree }.

Suppose I have a data type enum TreeTypes { TallTree, ShortTree, MediumTree }.

而且我必须根据一种特定的树类型初始化一些数据.

And I have to initialize some data based on one particular tree type.

目前我已经编写了这段代码:

Currently I have written this code:

int initialize(enum TreeTypes tree_type) {
    if (tree_type == TallTree) {
        init_tall_tree();
    }
    else if (tree_type == ShortTree) {
        init_short_tree();
    }
    else if (tree_type == MediumTree) {
        init_medium_tree();
    }
    return OK;
}

但这是某种愚蠢的代码重复.我没有使用任何强大的 C++ 功能，例如模板.

But this is some kind of stupid code repetition. I am not using any of the powerful C++ capabilities like templates.

我怎样才能更好地编写这段代码?

How could I write this code better?

谢谢，博达·西多.

推荐答案

您的代码适用于两个或三个值，但您是对的，当您拥有数百个值时，您需要一些更具工业实力的东西.两种可能的解决方案:

Your code is OK for two or three values, but you are right, you need something more industrial strength when you have hundreds of them. Two possible solutions:

• 使用类层次结构，而不是枚举 - 然后您可以使用虚函数并让编译器计算出要调用的实际函数

• use a class hierarchy, not enums - you can then use virtual functions and have the compiler work out which actual function to call

创建一个枚举映射 -> 函数，你在启动时初始化它 - 然后你的函数调用变成类似于 map[enum]->func()

create a map of enum -> function, which you initialise at startup - your function calls then become something like map[enum]->func()

模板在这里不能很好地工作，因为您试图在运行时做出决定，而模板在编译时做他们的事情.

Templates don't work so well here, because you are trying to make a decision at run-time, whereas templates do their stuff at compile-time.

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