反思与泛型类型 [英] Reflection and generic types

问题描述

我在写一些code的一类构造函数遍历类的所有属性和调用一个普通的静态方法，它从外部API填充我的课了数据。所以，我有这个作为一个例子类：

I'm writing some code for a class constructor which loops through all the properties of the class and calls a generic static method which populates my class with data from an external API. So I've got this as an example class:

public class MyClass{
  public string Property1 { get; set; }
  public int Property2 { get; set; }
  public bool Property3 { get; set; }

  public static T DoStuff<T>(string name){
    // get the data for the property from the external API
    // or if there's a problem return 'default(T)'
  }
}

现在在我的构造我想是这样的：

Now in my constructor I want something like this:

public MyClass(){
  var properties = this.GetType().GetProperties();
  foreach(PropertyInfo p in properties){
    p.SetValue(this, DoStuff(p.Name), new object[0]);
  }
}

所以上面的构造函数将抛出一个错误，因为我不提供泛型类型。

So the above constructor will thrown an error because I'm not supplying the generic type.

那么，如何通过在属性的类型？

So how do I pass in the type of the property in?

推荐答案

你想打电话DoStuff＆LT; T＆GT;以T =每个属性的类型？在这种情况下，原样你需要使用反射和MakeGenericMethod - 即

Do you want to call DoStuff<T> with T = the type of each property? In which case, "as is" you would need to use reflection and MakeGenericMethod - i.e.

var properties = this.GetType().GetProperties();
foreach (PropertyInfo p in properties)
{
    object value = typeof(MyClass)
    .GetMethod("DoStuff")
    .MakeGenericMethod(p.PropertyType)
    .Invoke(null, new object[] { p.Name });
    p.SetValue(this, value, null);
}

然而，这不是很pretty的。在现实中，我不知道它会不会只是为了更好地有：

However, this isn't very pretty. In reality I wonder if it wouldn't be better just to have:

static object DoStuff(string name, Type propertyType);
... and then
object value = DoStuff(p.Name, p.PropertyType);

什么是仿制药给你在这个例子吗？需要注意的是值类型仍然会得到反射通话过程中盒装等 - 而且当时拳击<一个href="http://msmvps.com/blogs/jon_skeet/archive/2008/10/08/why-boxing-doesn-t-keep-me-awake-at-nights.aspx"相对=nofollow>不是那么糟糕，因为你可能会认为。

最后，在许多情况下，TypeDescriptor.GetProperties（）比Type.GetProperties（）更合适。 - 允许灵活的对象模型等

Finally, in many scenarios, TypeDescriptor.GetProperties() is more appropriate than Type.GetProperties() - allows for flexible object models etc.

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