AppDomain.DefineDynamicAssembly Method (AssemblyName, AssemblyBuilderAccess, Evidence)

 
obsoleteCodeEntityM:System.AppDomain.DefineDynamicAssembly(System.Reflection.AssemblyName,System.Reflection.Emit.AssemblyBuilderAccess) Note: This API is now obsolete.

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

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

<ObsoleteAttribute("Assembly level declarative security is obsolete and is no longer enforced by the CLR by default.  See http://go.microsoft.com/fwlink/?LinkID=155570 for more information.")>
Public Function DefineDynamicAssembly (
	name As AssemblyName,
	access As AssemblyBuilderAccess,
	evidence As Evidence
) As AssemblyBuilder

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

A dynamic assembly with the specified name and features.

Exception Condition
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 Evidencethrough 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.

System_CAPS_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 sample 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 ofMyDynamicType. 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.


Imports System
Imports System.Reflection
Imports System.Reflection.Emit

Module Test

   Sub Main()
      Dim currentDomain As AppDomain = AppDomain.CurrentDomain

      InstantiateMyDynamicType(currentDomain)   'Failed!

      AddHandler currentDomain.AssemblyResolve, AddressOf MyResolveEventHandler

      InstantiateMyDynamicType(currentDomain)   'OK!
   End Sub 'Main

   Sub InstantiateMyDynamicType(domain As AppDomain)
      Try
         ' You must supply a valid fully qualified assembly name here.
         domain.CreateInstance("Assembly text name, Version, Culture, PublicKeyToken", "MyDynamicType")
      Catch e As Exception
         Console.WriteLine(e.Message)
      End Try
   End Sub 'InstantiateMyDynamicType

   Function MyResolveEventHandler(sender As Object, args As ResolveEventArgs) As System.Reflection.Assembly
      Return DefineDynamicAssembly(DirectCast(sender, AppDomain))
   End Function 'MyResolveEventHandler

   Function DefineDynamicAssembly(domain As AppDomain) As System.Reflection.Assembly
      ' Build a dynamic assembly using Reflection Emit API.

      Dim assemblyName As New AssemblyName()
      assemblyName.Name = "MyDynamicAssembly"

      Dim assemblyBuilder As AssemblyBuilder = domain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run)
      Dim moduleBuilder As ModuleBuilder = assemblyBuilder.DefineDynamicModule("MyDynamicModule")
      Dim typeBuilder As TypeBuilder = moduleBuilder.DefineType("MyDynamicType", TypeAttributes.Public)
      Dim constructorBuilder As ConstructorBuilder = typeBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, Nothing)
      Dim ilGenerator As ILGenerator = constructorBuilder.GetILGenerator()

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

      typeBuilder.CreateType()

      Return assemblyBuilder
   End Function 'DefineDynamicAssembly

End Module 'Test 

SecurityPermission

to load an assembly with evidence. Associated enumeration: SecurityPermissionFlag.ControlEvidence.

.NET Framework
Available since 1.1
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