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AppDomain.DefineDynamicAssembly Method (AssemblyName, AssemblyBuilderAccess, Evidence)

Defines a dynamic assembly using the specified name, access mode, and evidence.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)
public AssemblyBuilder DefineDynamicAssembly(
	AssemblyName name,
	AssemblyBuilderAccess access,
	Evidence evidence
)

Parameters

name
Type: System.Reflection.AssemblyName

The unique identity of the dynamic assembly.

access
Type: System.Reflection.Emit.AssemblyBuilderAccess

The mode in which the dynamic assembly will be accessed.

evidence
Type: System.Security.Policy.Evidence

The evidence supplied for the dynamic assembly. The evidence is used unaltered as the final set of evidence used for policy resolution.

Return Value

Type: System.Reflection.Emit.AssemblyBuilder
Represents the dynamic assembly created.

Implements

_AppDomain.DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess, Evidence)
ExceptionCondition
ArgumentNullException

name is null.

ArgumentException

The Name property of name is null.

-or-

The Name property of name begins with white space, or contains a forward or backward slash.

AppDomainUnloadedException

The operation is attempted on an unloaded application domain.

Only fully trusted callers can supply their evidence when defining a dynamic Assembly. The runtime will map the Evidence through the security policy to determine the granted permissions. Partially trusted callers must supply a null evidence. If evidence is null, the runtime copies the permission sets, that is, the current grant and deny sets, from the caller's Assembly to the dynamic Assembly being defined and marks policy as resolved.

If the dynamic Assembly is saved to disk, subsequent loads will get grants based on policies associated with the location where the Assembly was saved.

This method should only be used to define a dynamic assembly in the current application domain. For more information, see the Load(AssemblyName) method overload.

NoteNote:

During the development of code that emits dynamic assemblies, it is recommended that you use an overload of the DefineDynamicAssembly method that specifies evidence and permissions, supply the evidence you want the dynamic assembly to have, and include SecurityPermissionFlag.SkipVerification in refusedPermissions. Including SkipVerification in the refusedPermissions parameter ensures that the MSIL is verified. A limitation of this technique is that it also causes SecurityException to be thrown when used with code that demands full trust.

The following example demonstrates the DefineDynamicAssembly method and the AssemblyResolve event.

First, the code example tries to create an instance of MyDynamicType by calling the CreateInstance method with an invalid assembly name, and catches the resulting exception.

The code example then adds an event handler for the AssemblyResolve event, and again tries to create an instance of MyDynamicType. During the call to CreateInstance, the AssemblyResolve event is raised for the invalid assembly. The event handler creates a dynamic assembly that contains a type named MyDynamicType, gives the type a parameterless constructor, and returns the new dynamic assembly. The call to CreateInstance then finishes successfully, and the constructor for MyDynamicType displays a message at the console.

using System;
using System.Reflection;
using System.Reflection.Emit;

class Test {
   public static void Main() {
      AppDomain currentDomain = AppDomain.CurrentDomain;

      InstantiateMyDynamicType(currentDomain);   // Failed!

      currentDomain.AssemblyResolve += new ResolveEventHandler(MyResolveEventHandler);

      InstantiateMyDynamicType(currentDomain);   // OK!
   }

   static void InstantiateMyDynamicType(AppDomain domain) {
      try {
         // You must supply a valid fully qualified assembly name here. 
         domain.CreateInstance("Assembly text name, Version, Culture, PublicKeyToken", "MyDynamicType");
      } catch (Exception e) {
         Console.WriteLine(e.Message);
      }
   }   

   static Assembly MyResolveEventHandler(object sender, ResolveEventArgs args) {
      return DefineDynamicAssembly((AppDomain) sender);
   }

   static Assembly DefineDynamicAssembly(AppDomain domain) {
      // Build a dynamic assembly using Reflection Emit API.

      AssemblyName assemblyName = new AssemblyName();
      assemblyName.Name = "MyDynamicAssembly";

      AssemblyBuilder assemblyBuilder = domain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
      ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("MyDynamicModule");
      TypeBuilder typeBuilder = moduleBuilder.DefineType("MyDynamicType", TypeAttributes.Public);
      ConstructorBuilder constructorBuilder = typeBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, null);
      ILGenerator ilGenerator = constructorBuilder.GetILGenerator();

      ilGenerator.EmitWriteLine("MyDynamicType instantiated!");
      ilGenerator.Emit(OpCodes.Ret);

      typeBuilder.CreateType();

      return assemblyBuilder;
   }
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
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