当我寻找 System.Linq.Expression 功能(在代码中创建表达式树、编译它们、执行它们)时,我问自己这是否也可以用于类创建 - 特别是泛型类。
我期望类似 Expression.Class() 或 Expression.GenericClass() 的东西。查看这些方法,我没有看到任何这些方法。这将非常实用,因为我可以动态地构建业务对象——即时的。其实这就是我所需要的。如果 .net c# 中有另一种方法,我也感兴趣。
最佳答案
All-In-One Framework codeplex 项目中有一个示例说明如何执行此操作 http://1code.codeplex.com/
// Define the assembly and the module.
AppDomain appDomain = AppDomain.CurrentDomain;
AssemblyName assemblyName = new AssemblyName("EmittedAssembly");
AssemblyBuilder assembly = appDomain.DefineDynamicAssembly(
assemblyName, AssemblyBuilderAccess.RunAndSave);
// An assembly is made up of executable modules. For a single-module
// assembly, the module name and file name are the same as the
// assembly name.
ModuleBuilder module = assembly.DefineDynamicModule(
assemblyName.Name, assemblyName.Name + ".dll");
/////////////////////////////////////////////////////////////////////
// Declare the types (classes).
//
// Declare the class "ClassA"
TypeBuilder classA = module.DefineType("ClassA", TypeAttributes.Public);
// Declare the class "ClassB"
TypeBuilder classB = module.DefineType("ClassB", TypeAttributes.Public);
// Define the fields stringField, classBField
FieldBuilder stringField = classA.DefineField("stringField",
typeof(string), FieldAttributes.Private);
FieldBuilder classBField = classA.DefineField("classBField",
classB, FieldAttributes.Public);
/////////////////////////////////////////////////////////////////////
// Define the property ClassBProperty
PropertyBuilder classBProperty = classA.DefineProperty(
"ClassBProperty", PropertyAttributes.None, classB, null);
// The special set of attributes for the property set&get methods
MethodAttributes getSetAttr = MethodAttributes.Public |
MethodAttributes.SpecialName | MethodAttributes.HideBySig;
// Define the "get" accessor method for ClassBProperty
MethodBuilder classBGetProp = classA.DefineMethod(
"get_ClassBProperty", getSetAttr, classB, Type.EmptyTypes);
ILGenerator classBGetIL = classBGetProp.GetILGenerator();
classBGetIL.Emit(OpCodes.Ldarg_0);
classBGetIL.Emit(OpCodes.Ldfld, classBField);
classBGetIL.Emit(OpCodes.Ret);
// Define the "set" accessor method for ClassBProperty
MethodBuilder classBSetProp = classA.DefineMethod(
"set_ClassBProperty", getSetAttr, null, new Type[] { classB });
ILGenerator sampleSetIL = classBSetProp.GetILGenerator();
sampleSetIL.Emit(OpCodes.Ldarg_0);
sampleSetIL.Emit(OpCodes.Ldarg_1);
sampleSetIL.Emit(OpCodes.Stfld, classBField);
sampleSetIL.Emit(OpCodes.Ret);
// Map the get&set methods to PropertyBuilder
classBProperty.SetGetMethod(classBGetProp);
classBProperty.SetSetMethod(classBSetProp);
/////////////////////////////////////////////////////////////////////
// Define a method that uses the classBField
MethodBuilder classAMethod = classA.DefineMethod("ClassAMethod",
MethodAttributes.Public);
// Define the list generics and ienumerable generic
Type listOf = typeof(List<>);
Type enumOf = typeof(IEnumerable<>);
Type listOfClassA = listOf.MakeGenericType(classA);
Type enumOfClassA = enumOf.MakeGenericType(classA);
// Define the method, ClassBMethod, for ClassB
MethodBuilder classBMethod = classB.DefineMethod("ClassBMethod",
MethodAttributes.Public, typeof(void), new Type[] { listOfClassA });
classBMethod.DefineParameter(1, ParameterAttributes.None, "list");
// Write the body of ClassAMethod that calls ClassBMethod
ILGenerator ilgenA = classAMethod.GetILGenerator();
ilgenA.Emit(OpCodes.Nop);
ilgenA.Emit(OpCodes.Ldarg_0);
ilgenA.Emit(OpCodes.Ldfld, classBField);
ilgenA.Emit(OpCodes.Ldnull);
ilgenA.Emit(OpCodes.Callvirt, classBMethod);
ilgenA.Emit(OpCodes.Ret);
/////////////////////////////////////////////////////////////////////
// Create the types.
//
classA.CreateType();
classB.CreateType();
/////////////////////////////////////////////////////////////////////
// Save the assembly.
//
assembly.Save(assemblyName.Name + ".dll");
抱歉,这有点长..:-P
关于c# - 在 .net c# 代码中创建类类型,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3378033/