[转]C#使用CodeDom动态生成代码

原文链接：让代码帮我们写代码（一）
示例全部来自转载的文章，这里只是简单做了一些修改，留给自己以后使用。
定义一个 ClassDescription 类来帮助描述需要生成的 class 长啥样：

public class ClassDescription
{
    public string SpaceName { get; set; }
    public string AssemblyName { get; set; }
    public string ClassName { get; set; }
    public List<PropertyDescription> Properties { get; set; }
}
public class PropertyDescription
{
    public string Name { get; set; }
    public Type Type { get; set; }
    private string des = string.Empty;
    public string Des 
    {
        get 
        {
            return (des == string.Empty) ? Name : des;
        }
        set 
        {
            if (!string.IsNullOrWhiteSpace(value)) des = value;
        }
    }
}

用 ClassDescription 来定义 User 类，它里面有 2 个属性 Name，Age：

var userClassDesc = new ClassDescription()
{
    AssemblyName = "TestAssembly",
    SpaceName = "TestSpace",
    ClassName = "User",
    Properties = new List<PropertyDescription> {
        new PropertyDescription {
            Type = typeof(string),
            Name = "Name"
        },
        new PropertyDescription
        {
            Type = typeof(int),
            Name = "Age"
        }
    }
};

使用 CodeDom 来动态生成代码：

public static Type Generate(ClassDescription clazz)
{
    const string clzTemp =
        @"
        using System;
        using System.IO;
        using System.ComponentModel;
        namespace @moduleName 
        {
        
            public class @className 
            {
                @properties
                public void Load()
                {
                    //@loadMethod
                }
                
            }
        }
        ";
    const string propTemp = 
        @"
                [Description(""propDes"")] 
                public @type @propName { get;set; }
        ";
    
    var properties = new StringBuilder("");
    foreach (var item in clazz.Properties)
    {
        string strProp = propTemp
            .Replace("@propDes", item.Des)
            .Replace("@type", item.Type.Name)                    
            .Replace("@propName", item.Name);
       
        properties.AppendLine(strProp);
    }
    string sourceCode = clzTemp
        .Replace("@moduleName", clazz.SpaceName)
        .Replace("@className", clazz.ClassName)
        .Replace("@properties", properties.ToString());
    Console.WriteLine(sourceCode);
    var codeProvider = new CSharpCodeProvider();
    CompilerParameters param = new CompilerParameters();
    param.OutputAssembly = clazz.AssemblyName;
    param.ReferencedAssemblies.Add("System.dll");
    param.ReferencedAssemblies.Add("mscorlib.dll");            
    CompilerResults result = codeProvider.CompileAssemblyFromSource(param, sourceCode);
    Type type = null;
    if (result.Errors.Count > 0)
    {
        for (int i = 0; i < result.Errors.Count; i++) 
        {
            Console.WriteLine($"Errors{i}: {result.Errors[i]}");
        }
    }
    else 
    {
        type = result.CompiledAssembly.GetType($"{clazz.SpaceName}.{clazz.ClassName}");
    }
    return type;
}

代码测试：

Type type = Generate(userClassDesc);
dynamic user = Activator.CreateInstance(type, null);           
user.Name = "mj";
user.Age = 18;