从文本名称实例化一个类 [英] Instantiate a class from its textual name

问题描述

不要问我为什么，但我需要做到以下几点：

Don't ask me why but I need to do the following:

string ClassName = "SomeClassName";  
object o = MagicallyCreateInstance("SomeClassName");

我想知道有多少种方法做，这是和接近其方案中使用。

I want to know how many ways there are to do this is and which approach to use in which scenario.

例如：

• Activator.CreateInstance


• Assembly.GetExecutingAssembly.CreateInstance（）


• 任何其他的建议将是AP preciated

这问题并不意味着是一个开放式的讨论，因为我相信只有这么多的方法可以做到这一点。

This question is not meant to be an open ended discussion because I am sure there are only so many ways this can be achieved.

推荐答案

下面就是该方法可能看起来是这样的：

Here's what the method may look like:

private static object MagicallyCreateInstance(string className)
{
    var assembly = Assembly.GetExecutingAssembly();

    var type = assembly.GetTypes()
        .First(t => t.Name == className);

    return Activator.CreateInstance(type);
}

上面的code假定：

The code above assumes that:

• 您正在寻找一类是在当前执行的程序集（这可以调整 - 只需更改组装来无论你需要）


• 恰好有一个类你在一个组装查找名称


• 类有一个默认的构造函数

• you are looking for a class that is in the currently executing assembly (this can be adjusted - just change assembly to whatever you need)
• there is exactly one class with the name you are looking for in that assembly
• the class has a default constructor

更新：

下面是如何让所有从给定的类派生（在相同的程序集的定义）的类：

Here's how to get all the classes that derive from a given class (and are defined in the same assembly):

private static IEnumerable<Type> GetDerivedTypesFor(Type baseType)
{
    var assembly = Assembly.GetExecutingAssembly();

    return assembly.GetTypes()
        .Where(baseType.IsAssignableFrom)
        .Where(t => baseType != t);
}

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