索引开关语句，还是等价的？ .net，C＃ [英] indexed switch statement, or equivalent? .net, C#

问题描述

我想建立一个接受一个字符串参数的方法，一个我想返回一个基于参数的特定成员的对象。因此，最简单的方法是构建一个switch语句：

I want to build a method which accepts a string param, and an object which I would like to return a particular member of based on the param. So, the easiest method is to build a switch statement:

public GetMemberByName(MyObject myobj, string name)
{
   switch(name){
     case "PropOne": return myobj.prop1;
     case "PropTwo": return myobj.prop2; 
   }
}

这工作正常，但我可能会结束一个相当大的列表...所以我好奇，如果有一种方式，没有编写一堆嵌套的if-else结构，以索引的方式完成这一点，以便通过索引找到匹配字段，而不是通过交换机找到，直到找到了一个匹配。

This works fine, but I may wind up with a rather large list... So I was curious if there's a way, without writing a bunch of nested if-else structures, to accomplish this in an indexed way, so that the matching field is found by index instead of falling through a switch until a match is found.

我考虑使用 Dictionary< string，something> 来快速访问匹配的字符串（作为键成员），但是由于我想要访问一个传入对象的成员，我不知道这可以如何实现。

I considered using a Dictionary<string, something> to give fast access to the matching strings (as the key member) but since I'm wanting to access a member of a passed-in object, I'm not sure how this could be accomplished.

• 我专门设法避免反射等等，以实现非常快速的实现。我可能会使用代码生成，所以解决方案不需要很小/紧密等。

• I'm specifically trying to avoid reflection etc in order to have a very fast implementation. I'll likely use code generation, so the solution doesn't need to be small/tight etc.

我最初正在构建一个字典，但每个对象正在初始化它。所以我开始把它移到一个可以根据键 - 一个switch语句查找值的单一方法。但是，由于我不再索引，我恐怕连续查找调用这个方法会很慢。

I originally was building a dictionary of but each object was initializing it. So I began to move this to a single method that can look up the values based on the keys- a switch statement. But since I'm no longer indexed, I'm afraid the continuous lookups calling this method would be slow.

SO：我正在寻找一种将索引/散列查找（如Dictionary使用）的性能与返回特定属性的方法相结合，在对象中。我可能会在每个类中使用静态方法。

SO: I am looking for a way to combine the performance of an indexed/hashed lookup (like the Dictionary uses) with returning particular properties of a passed-in object. I'll likely put this in a static method within each class it is used for.

推荐答案

这是一个简单的方法可以使用字典：

Here's an easy way you can use a dictionary:

    Dictionary<string, Func<MyObject, object>> propertyNameAssociations;

    private void BuildPropertyNameAssociations()
    {
        propertyNameAssociations = new Dictionary<string, Func<MyObject, object>>();
        propertyNameAssociations.Add("PropOne", x => x.prop1);
        propertyNameAssociations.Add("PropTwo", x => x.prop2);
    }

    public object GetMemberByName(MyObject myobj, string name)
    {
        if (propertyNameAssociations.Contains(name))
            return propertyNameAssociations[name](myobj);
        else
            return null;
    }

这篇关于索引开关语句，还是等价的？ .net，C＃的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！