C# - Reflection

The .Net Framework provides a reflection capability that allows you to obtain information about assemblies, modules and types as well as being able to dynamically create instances of types. In this article, I explain how to get type information and create instances dynamically. Let's start with a simple example with an existing .Net class. Consider at run-time, you want to get a list of class properties. To achieve this, we must first import the System.Reflection namespace. Once imported the Type class can be used to get details about a class using the GetType() method as seen in the example below.

1. using System;  
2. using System.Reflection;  
3.  
4. class Program  
5. {  
6.     static void Main(string[] args)  
7.     {  
8.         PropertyInfo[] propInfoList = Type.GetType("System.DateTime").GetProperties();  
9.  
10.         foreach (PropertyInfo propInfo in propInfoList)  
11.         {  
12.             Console.WriteLine(propInfo.Name);  
13.         }  
14.  
15.         Console.ReadKey();  
16.     }  
17. } 

In the above code the GetProperties() method will return an array of PropertyInfo objects for the System.DateTime Type. The PropertyInfo class has a Name property, which will return the public property name of the reflecting class. To get a list of non public properties, you can use a bitmask comprised of System.Reflection.BindingFlags as shown in the example below.

1. PropertyInfo[] propInfoList = Type.GetType("System.DateTime").GetProperties(BindingFlags.NonPublic | BindingFlags.Instance); 

We can also use the GetMethod() method to get a list of public methods.

1. MethodInfo[] methodInfoList = Type.GetType("System.DateTime").GetMethods();  
2.  
3. foreach (MethodInfo methodInfo in methodInfoList)  
4. {  
5.     Console.WriteLine(methodInfo.Name);  
6. } 

BindingFlags can also be used to get a list of non public methods. Reflection can also be used to get a list of all class attributes using the GetCustomAttributes() method.

1. object[] attrs = Type.GetType("System.String").GetCustomAttributes(true);  
2.  
3. foreach (Attribute attr in attrs)  
4. {  
5.     Console.WriteLine(attr.ToString());  
6. } 

You can also filter the attributes if you need to find a particular attribute.

1. object[] attrs = Type.GetType("System.String").GetCustomAttributes(Type.GetType("System.SerializableAttribute"), true);