AppDomain.DynamicDirectory Property

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

AppDomain.cs

Gets the directory that the assembly resolver uses to probe for dynamically created assemblies.

public:
 property System::String ^ DynamicDirectory { System::String ^ get(); };

public string? DynamicDirectory { get; }

member this.DynamicDirectory : string

Public ReadOnly Property DynamicDirectory As String

Property Value

String

The directory that the assembly resolver uses to probe for dynamically created assemblies.

Exceptions

AppDomainUnloadedException

The operation is attempted on an unloaded application domain.

Examples

The following example creates an application domain with a directory for dynamic assemblies, emits a dynamic assembly and stores it in the dynamic directory, and then loads the assembly into the new application domain and uses it.

The example creates an AppDomainSetup object and sets its ApplicationName property to "Example" and its DynamicBase property to "C:\DynamicAssemblyDir". The example then displays the DynamicBase property, to show that the hash code of the application name has been appended as a subdirectory of the path that was originally assigned.

Note

The base directory in this example is intended to be outside the probing path for the example application. Be sure to compile the example in a different location. Delete the base directory and all its subdirectories each time you run the example.

The example creates a new application domain, using the AppDomainSetup object. The example uses the DynamicDirectory property to retrieve the name of the directory, so it can create the directory. (The example could just as easily create the directory beforehand by concatenating the original path, the hash code of the application name, and the application name.)

The example has a GenerateDynamicAssembly method that emits an assembly named DynamicHelloWorld.dll and stores it in the new application domain's dynamic directory. The dynamic assembly contains one type, HelloWorld, that has a static method (Shared method in Visual Basic) named HelloFromAD. Calling this method displays the name of the application domain.

The Example class derives from MarshalByRefObject, so the example can create an instance of the class in the new application domain and call its Test method. The Test method loads the dynamic assembly by its display name and calls the static HelloFromAD method.

You can show that the dynamic directory is searched after the normal probing paths by writing code for an assembly named DynamicHelloWorld.dll and compiling it in the same directory as this example. The assembly must have a class named HelloWorld with a static method named HelloFromAD. This method does not have to have the same functionality as the one in the example; it can simply display a string to the console. The assembly must also have an AssemblyVersionAttribute attribute that sets its version to 1.0.0.0. When you run the example, the assembly you compiled in the current directory is found before the dynamic directory is searched.

using namespace System;
using namespace System::Reflection;
using namespace System::Reflection::Emit;

public ref class Example : MarshalByRefObject
{
public:
   void Test()
   {
      Assembly^ dynAssem = Assembly::Load(
         "DynamicHelloWorld, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null");

      Type^ myType = dynAssem->GetType("HelloWorld");
      myType->InvokeMember("HelloFromAD", BindingFlags::Public | 
         BindingFlags::Static | BindingFlags::InvokeMethod, 
         Type::DefaultBinder, nullptr, nullptr);
   }
};


static void GenerateDynamicAssembly(String^ location)
{
   // Define the dynamic assembly and the module. There is only one
   // module in this assembly. Note that the call to DefineDynamicAssembly 
   // specifies the location where the assembly will be saved. The 
   // assembly version is 1.0.0.0.
   //
   AssemblyName^ asmName = gcnew AssemblyName("DynamicHelloWorld");
   asmName->Version = gcnew Version("1.0.0.0");

   AssemblyBuilder^ ab = 
      AppDomain::CurrentDomain->DefineDynamicAssembly( 
         asmName, AssemblyBuilderAccess::Save, location);

   String^ moduleName = asmName->Name + ".exe";
   ModuleBuilder^ mb = ab->DefineDynamicModule(asmName->Name, moduleName);
   
   // Define the "HelloWorld" type, with one static method.
   TypeBuilder^ tb = mb->DefineType("HelloWorld", TypeAttributes::Public);
   MethodBuilder^ hello = tb->DefineMethod("HelloFromAD", 
      MethodAttributes::Public | MethodAttributes::Static, nullptr, nullptr);

   // The method displays a message that contains the name of the application
   // domain where the method is executed.
   ILGenerator^ il = hello->GetILGenerator();
   il->Emit(OpCodes::Ldstr, "Hello from '{0}'!");
   il->Emit(OpCodes::Call, AppDomain::typeid->GetProperty("CurrentDomain")->GetGetMethod());
   il->Emit(OpCodes::Call, AppDomain::typeid->GetProperty("FriendlyName")->GetGetMethod());
   il->Emit(OpCodes::Call, Console::typeid->GetMethod("WriteLine", 
                            gcnew array<Type^> { String::typeid, String::typeid }));
   il->Emit(OpCodes::Ret);

   // Complete the HelloWorld type and save the assembly. The assembly
   // is placed in the location specified by DefineDynamicAssembly.
   Type^ myType = tb->CreateType();
   ab->Save(moduleName);
};

void main()
{
   // Prepare to create a new application domain.
   AppDomainSetup^ setup = gcnew AppDomainSetup();

   // Set the application name before setting the dynamic base.
   setup->ApplicationName = "Example";
   
   // Set the location of the base directory where assembly resolution 
   // probes for dynamic assemblies. Note that the hash code of the 
   // application name is concatenated to the base directory name you 
   // supply. 
   setup->DynamicBase = "C:\\DynamicAssemblyDir";
   Console::WriteLine("DynamicBase is set to '{0}'.", setup->DynamicBase);

   AppDomain^ ad = AppDomain::CreateDomain("MyDomain", nullptr, setup);
   
   // The dynamic directory name is the dynamic base concatenated with
   // the application name: <DynamicBase>\<hash code>\<ApplicationName>
   String^ dynamicDir = ad->DynamicDirectory;
   Console::WriteLine("Dynamic directory is '{0}'.", dynamicDir);

   // The AssemblyBuilder won't create this directory automatically.
   if (!System::IO::Directory::Exists(dynamicDir))
   {
      Console::WriteLine("Creating the dynamic directory.");
      System::IO::Directory::CreateDirectory(dynamicDir);
   }

   // Generate a dynamic assembly and store it in the dynamic 
   // directory.
   GenerateDynamicAssembly(dynamicDir);

   // Create an instance of the Example class in the application domain,
   // and call its Test method to load the dynamic assembly and use it.
   Example^ ex = (Example^) ad->CreateInstanceAndUnwrap( 
         Example::typeid->Assembly->FullName, "Example");
   ex->Test();
}

/* This example produces output similar to the following:

DynamicBase is set to 'C:\DynamicAssemblyDir\5e4a7545'.
Dynamic directory is 'C:\DynamicAssemblyDir\5e4a7545\Example'.
Creating the dynamic directory.
Hello from 'MyDomain'!
 */

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

public class AddDynamicBaseSnippet : MarshalByRefObject
{
   static void Main()
   {
      // Prepare to create a new application domain.
      AppDomainSetup setup = new AppDomainSetup();

      // Set the application name before setting the dynamic base.
      setup.ApplicationName = "Example";

      // Set the location of the base directory where assembly resolution
      // probes for dynamic assemblies. Note that the hash code of the
      // application name is concatenated to the base directory name you
      // supply.
      setup.DynamicBase = "C:\\DynamicAssemblyDir";
      Console.WriteLine("DynamicBase is set to '{0}'.", setup.DynamicBase);

      AppDomain ad = AppDomain.CreateDomain("MyDomain", null, setup);

      // The dynamic directory name is the dynamic base concatenated with
      // the application name: <DynamicBase>\<hash code>\<ApplicationName>
      string dynamicDir = ad.DynamicDirectory;
      Console.WriteLine("Dynamic directory is '{0}'.", dynamicDir);

      // The AssemblyBuilder won't create this directory automatically.
      if (!System.IO.Directory.Exists(dynamicDir))
      {
         Console.WriteLine("Creating the dynamic directory.");
         System.IO.Directory.CreateDirectory(dynamicDir);
      }

      // Generate a dynamic assembly and store it in the dynamic
      // directory.
      GenerateDynamicAssembly(dynamicDir);

      // Create an instance of the Example class in the application domain,
      // and call its Test method to load the dynamic assembly and use it.
      AddDynamicBaseSnippet ex = (AddDynamicBaseSnippet) ad.CreateInstanceAndUnwrap(
         typeof(AddDynamicBaseSnippet).Assembly.FullName, "Example");
      ex.Test();
   }

   public void Test()
   {
      Assembly dynAssem = Assembly.Load(
         "DynamicHelloWorld, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null");

      Type myType = dynAssem.GetType("HelloWorld");
      myType.InvokeMember("HelloFromAD", BindingFlags.Public |
         BindingFlags.Static | BindingFlags.InvokeMethod,
         Type.DefaultBinder, null, null);
   }

   private static void GenerateDynamicAssembly(string location)
   {
      // Define the dynamic assembly and the module. There is only one
      // module in this assembly. Note that the call to DefineDynamicAssembly
      // specifies the location where the assembly will be saved. The
      // assembly version is 1.0.0.0.
      //
      AssemblyName asmName = new AssemblyName("DynamicHelloWorld");
      asmName.Version = new Version("1.0.0.0");

      AssemblyBuilder ab =
         AppDomain.CurrentDomain.DefineDynamicAssembly(
            asmName, AssemblyBuilderAccess.Save, location);

      String moduleName = asmName.Name + ".exe";
      ModuleBuilder mb = ab.DefineDynamicModule(asmName.Name, moduleName);

      // Define the "HelloWorld" type, with one static method.
      TypeBuilder tb = mb.DefineType("HelloWorld", TypeAttributes.Public);
      MethodBuilder hello = tb.DefineMethod("HelloFromAD",
         MethodAttributes.Public | MethodAttributes.Static, null, null);

      // The method displays a message that contains the name of the application
      // domain where the method is executed.
      ILGenerator il = hello.GetILGenerator();
      il.Emit(OpCodes.Ldstr, "Hello from '{0}'!");
      il.Emit(OpCodes.Call, typeof(AppDomain).GetProperty("CurrentDomain").GetGetMethod());
      il.Emit(OpCodes.Call, typeof(AppDomain).GetProperty("FriendlyName").GetGetMethod());
      il.Emit(OpCodes.Call, typeof(Console).GetMethod("WriteLine",
                             new Type[] { typeof(String), typeof(String) }));
      il.Emit(OpCodes.Ret);

      // Complete the HelloWorld type and save the assembly. The assembly
      // is placed in the location specified by DefineDynamicAssembly.
      Type myType = tb.CreateType();
      ab.Save(moduleName);
   }
}

/* This example produces output similar to the following:

DynamicBase is set to 'C:\DynamicAssemblyDir\5e4a7545'.
Dynamic directory is 'C:\DynamicAssemblyDir\5e4a7545\Example'.
Creating the dynamic directory.
Hello from 'MyDomain'!
 */

open System
open System.Reflection
open System.Reflection.Emit

type Example() =
    inherit MarshalByRefObject()
    member _.Test() =
        let dynAssem = 
            Assembly.Load "DynamicHelloWorld, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"

        let myType = dynAssem.GetType "HelloWorld"
        myType.InvokeMember("HelloFromAD", BindingFlags.Public |||
            BindingFlags.Static ||| BindingFlags.InvokeMethod,
            Type.DefaultBinder, null, null)
        |> ignore

    static member GenerateDynamicAssembly(location: string) =
        // Define the dynamic assembly and the module. There is only one
        // module in this assembly. Note that the call to DefineDynamicAssembly
        // specifies the location where the assembly will be saved. The
        // assembly version is 1.0.0.0.
        let asmName = AssemblyName "DynamicHelloWorld"
        asmName.Version <- Version "1.0.0.0"

        let ab = AppDomain.CurrentDomain.DefineDynamicAssembly(asmName, AssemblyBuilderAccess.Save, location)

        let moduleName = asmName.Name + ".exe"
        let mb = ab.DefineDynamicModule(asmName.Name, moduleName)

        // Define the "HelloWorld" type, with one static method.
        let tb = mb.DefineType("HelloWorld", TypeAttributes.Public)
        let hello = 
            tb.DefineMethod("HelloFromAD", MethodAttributes.Public ||| MethodAttributes.Static, null, null)

        // The method displays a message that contains the name of the application
        // domain where the method is executed.
        let il = hello.GetILGenerator()
        il.Emit(OpCodes.Ldstr, "Hello from '{0}'!")
        il.Emit(OpCodes.Call, typeof<AppDomain>.GetProperty("CurrentDomain").GetGetMethod())
        il.Emit(OpCodes.Call, typeof<AppDomain>.GetProperty("FriendlyName").GetGetMethod())
        il.Emit(OpCodes.Call, typeof<Console>.GetMethod("WriteLine", [| typeof<string>; typeof<String> |]))
        il.Emit OpCodes.Ret

        // Complete the HelloWorld type and save the assembly. The assembly
        // is placed in the location specified by DefineDynamicAssembly.
        let myType = tb.CreateType()
        ab.Save moduleName

// Prepare to create a new application domain.
let setup = AppDomainSetup()

// Set the application name before setting the dynamic base.
setup.ApplicationName <- "Example"

// Set the location of the base directory where assembly resolution
// probes for dynamic assemblies. Note that the hash code of the
// application name is concatenated to the base directory name you
// supply.
setup.DynamicBase <- "C:\\DynamicAssemblyDir"
printfn $"DynamicBase is set to '{setup.DynamicBase}'."

let ad = AppDomain.CreateDomain("MyDomain", null, setup)

// The dynamic directory name is the dynamic base concatenated with
// the application name: <DynamicBase>\<hash code>\<ApplicationName>
let dynamicDir = ad.DynamicDirectory
printfn $"Dynamic directory is '{dynamicDir}'."

// The AssemblyBuilder won't create this directory automatically.
if not (System.IO.Directory.Exists dynamicDir) then
    printfn "Creating the dynamic directory."
    System.IO.Directory.CreateDirectory dynamicDir
    |> ignore

// Generate a dynamic assembly and store it in the dynamic
// directory.
Example.GenerateDynamicAssembly dynamicDir

// Create an instance of the Example class in the application domain,
// and call its Test method to load the dynamic assembly and use it.
let ex = ad.CreateInstanceAndUnwrap(typeof<Example>.Assembly.FullName, "Example") :?> Example
ex.Test()

(* This example produces output similar to the following:

DynamicBase is set to 'C:\DynamicAssemblyDir\5e4a7545'.
Dynamic directory is 'C:\DynamicAssemblyDir\5e4a7545\Example'.
Creating the dynamic directory.
Hello from 'MyDomain'!
 *)

Imports System.Reflection
Imports System.Reflection.Emit

Public Class Example 
   Inherits MarshalByRefObject
   
   Shared Sub Main(args() As String)

      ' Prepare to create a new application domain.
      Dim setup As New AppDomainSetup()

      ' Set the application name before setting the dynamic base.
      setup.ApplicationName = "Example"
      
      ' Set the location of the base directory where assembly resolution 
      ' probes for dynamic assemblies. Note that the hash code of the 
      ' application name is concatenated to the base directory name you 
      ' supply. 
      setup.DynamicBase = "C:\DynamicAssemblyDir"
      Console.WriteLine("DynamicBase is set to '{0}'.", setup.DynamicBase)

      Dim ad As AppDomain = AppDomain.CreateDomain("MyDomain", Nothing, setup)
      
      ' The dynamic directory name is the dynamic base concatenated with
      ' the application name: <DynamicBase>\<hash code>\<ApplicationName>
      Dim dynamicDir As String = ad.DynamicDirectory 
      Console.WriteLine("Dynamic directory is '{0}'.", dynamicDir)

      ' The AssemblyBuilder won't create this directory automatically.
      If Not System.IO.Directory.Exists(dynamicDir) Then 
         Console.WriteLine("Creating the dynamic directory.")
         System.IO.Directory.CreateDirectory(dynamicDir)
      End If

      ' Generate a dynamic assembly and store it in the dynamic 
      ' directory.
      GenerateDynamicAssembly(dynamicDir) 

      ' Create an instance of the Example class in the application domain,
      ' and call its Test method to load the dynamic assembly and use it.  
      Dim ex As Example = CType( _
         ad.CreateInstanceAndUnwrap( _
            GetType(Example).Assembly.FullName, "Example"), Example)
      ex.Test()
   End Sub

   Public Sub Test() 

      Dim dynAssem As [Assembly] = Assembly.Load(
         "DynamicHelloWorld, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null")

      Dim myType As Type = dynAssem.GetType("HelloWorld")
      myType.InvokeMember("HelloFromAD", BindingFlags.Public Or _
         BindingFlags.Static Or BindingFlags.InvokeMethod, _
         Type.DefaultBinder, Nothing, Nothing) 'New Object() {})
   End Sub


   Private Shared Sub GenerateDynamicAssembly(ByVal location As String)
      
      ' Define the dynamic assembly and the module. There is only one
      ' module in this assembly. Note that the call to DefineDynamicAssembly 
      ' specifies the location where the assembly will be saved. The 
      ' assembly version is 1.0.0.0.
      '
      Dim asmName As New AssemblyName("DynamicHelloWorld")
      asmName.Version = New Version("1.0.0.0")

      Dim ab As AssemblyBuilder = _
         AppDomain.CurrentDomain.DefineDynamicAssembly( _
            asmName, AssemblyBuilderAccess.Save, location)

      Dim moduleName As String = asmName.Name & ".dll"
      Dim mb As ModuleBuilder = ab.DefineDynamicModule(asmName.Name, moduleName)
      
      ' Define the "HelloWorld" type, with one static method.
      Dim tb As TypeBuilder = mb.DefineType("HelloWorld", TypeAttributes.Public)
      Dim hello As MethodBuilder = tb.DefineMethod("HelloFromAD", _
         MethodAttributes.Public Or MethodAttributes.Static, Nothing, Nothing)

      ' The method displays a message that contains the name of the application
      ' domain where the method is executed.
      Dim il As ILGenerator = hello.GetILGenerator()
      il.Emit(OpCodes.Ldstr, "Hello from '{0}'!")
      il.Emit(OpCodes.Call, GetType(AppDomain).GetProperty("CurrentDomain").GetGetMethod())
      il.Emit(OpCodes.Call, GetType(AppDomain).GetProperty("FriendlyName").GetGetMethod())
      il.Emit(OpCodes.Call, GetType(Console).GetMethod("WriteLine", _
                             New Type() { GetType(String), GetType(String) }))
      il.Emit(OpCodes.Ret)

      ' Complete the HelloWorld type and save the assembly. The assembly
      ' is placed in the location specified by DefineDynamicAssembly.
      Dim myType As Type = tb.CreateType()
      ab.Save(moduleName)
   End Sub
End Class 

' This example produces output similar to the following:
'
'DynamicBase is set to 'C:\DynamicAssemblyDir\5e4a7545'.
'Dynamic directory is 'C:\DynamicAssemblyDir\5e4a7545\Example'.
'Creating the dynamic directory.
'Hello from 'MyDomain'!

Remarks

To set the dynamic directory, assign a base directory path to the AppDomainSetup.DynamicBase property of the AppDomainSetup object that will be used to create the new application domain. The base directory path you assign to the property is modified by the addition of a subdirectory whose simple name is the hash code of the string you assign to the AppDomainSetup.ApplicationName property, so the format of the base directory is original path\hash code. The dynamic directory is a subdirectory of this base directory. Its simple name is the value of the AppDomainSetup.ApplicationName property, so its format is original path\hash code\application name.