Add-Type

Syntax

Add-Type
   [-TypeDefinition] <String>
   [-Language <Language>]
   [-ReferencedAssemblies <String[]>]
   [-OutputAssembly <String>]
   [-OutputType <OutputAssemblyType>]
   [-PassThru]
   [-IgnoreWarnings]
   [-CompilerOptions <String[]>]
   [<CommonParameters>]

Add-Type
   [-Name] <String>
   [-MemberDefinition] <String[]>
   [-Namespace <String>]
   [-UsingNamespace <String[]>]
   [-Language <Language>]
   [-ReferencedAssemblies <String[]>]
   [-OutputAssembly <String>]
   [-OutputType <OutputAssemblyType>]
   [-PassThru]
   [-IgnoreWarnings]
   [-CompilerOptions <String[]>]
   [<CommonParameters>]

Add-Type
   [-Path] <String[]>
   [-ReferencedAssemblies <String[]>]
   [-OutputAssembly <String>]
   [-OutputType <OutputAssemblyType>]
   [-PassThru]
   [-IgnoreWarnings]
   [-CompilerOptions <String[]>]
   [<CommonParameters>]

Add-Type
   -LiteralPath <String[]>
   [-ReferencedAssemblies <String[]>]
   [-OutputAssembly <String>]
   [-OutputType <OutputAssemblyType>]
   [-PassThru]
   [-IgnoreWarnings]
   [-CompilerOptions <String[]>]
   [<CommonParameters>]

Add-Type
   -AssemblyName <String[]>
   [-PassThru]
   [<CommonParameters>]

Description

The Add-Type cmdlet lets you define a Microsoft .NET Core class in your PowerShell session. You can then instantiate objects, by using the New-Object cmdlet, and use the objects just as you would use any .NET Core object. If you add an Add-Type command to your PowerShell profile, the class is available in all PowerShell sessions.

You can specify the type by specifying an existing assembly or source code files, or you can specify the source code inline or saved in a variable. You can even specify only a method and Add-Type defines and generates the class. On Windows, you can use this feature to make Platform Invoke (P/Invoke) calls to unmanaged functions in PowerShell. If you specify source code, Add-Type compiles the specified source code and generates an in-memory assembly that contains the new .NET Core types.

You can use the parameters of Add-Type to specify an alternate language and compiler, C# is the default, compiler options, assembly dependencies, the class namespace, the names of the type, and the resulting assembly.

Beginning in PowerShell 7, Add-Type does not compile a type if a type with the same name already exists. Also, Add-Type looks for assemblies in a ref folder under the folder that contains pwsh.dll .

Examples

Example 1: Add a .NET type to a session

This example adds the BasicTest class to the session by specifying source code that is stored in a variable. The BasicTest class is used to add integers, create an object, and multiply integers.

$Source = @"
public class BasicTest
{
  public static int Add(int a, int b)
    {
        return (a + b);
    }
  public int Multiply(int a, int b)
    {
    return (a * b);
    }
}
"@

Add-Type -TypeDefinition $Source
[BasicTest]::Add(4, 3)
$BasicTestObject = New-Object BasicTest
$BasicTestObject.Multiply(5, 2)

The $Source variable stores the source code for the class. The type has a static method called Add and a non-static method called Multiply .

The Add-Type cmdlet adds the class to the session. Because it's using inline source code, the command uses the TypeDefinition parameter to specify the code in the $Source variable.

The Add static method of the BasicTest class uses the double-colon characters ( :: ) to specify a static member of the class. The integers are added and the sum is displayed.

The New-Object cmdlet instantiates an instance of the BasicTest class. It saves the new object in the $BasicTestObject variable.

$BasicTestObject uses the Multiply method. The integers are multiplied and the product is displayed.

Example 2: Examine an added type

This example uses the Get-Member cmdlet to examine the objects that the Add-Type and New-Object cmdlets created in Example 1 .

[BasicTest] | Get-Member

TypeName: System.RuntimeType

Name                 MemberType Definition
----                 ---------- ----------
AsType               Method     type AsType()
Clone                Method     System.Object Clone(), System.Object ICloneable.Clone()
Equals               Method     bool Equals(System.Object obj), bool Equals(type o)
FindInterfaces       Method     type[] FindInterfaces(System.Reflection.TypeFilter filter...
...

[BasicTest] | Get-Member -Static

TypeName: BasicTest

Name            MemberType Definition
----            ---------- ----------
Add             Method     static int Add(int a, int b)
Equals          Method     static bool Equals(System.Object objA, System.Object objB)
new             Method     BasicTest new()
ReferenceEquals Method     static bool ReferenceEquals(System.Object objA, System.Object objB)

$BasicTestObject | Get-Member

TypeName: BasicTest

Name        MemberType Definition
----        ---------- ----------
Equals      Method     bool Equals(System.Object obj)
GetHashCode Method     int GetHashCode()
GetType     Method     type GetType()
Multiply    Method     int Multiply(int a, int b)
ToString    Method     string ToString()

The Get-Member cmdlet gets the type and members of the BasicTest class that Add-Type added to the session. The Get-Member command reveals that it's a System.RuntimeType object, which is derived from the System.Object class.

The Get-Member Static parameter gets the static properties and methods of the BasicTest class. The output shows that the Add method is included.

The Get-Member cmdlet gets the members of the object stored in the $BasicTestObject variable. $BasicTestObject was created by using the New-Object cmdlet with the BasicTest class. The output reveals that the value of the $BasicTestObject variable is an instance of the BasicTest class and that it includes a member called Multiply .

Example 3: Add types from an assembly

This example adds the classes from the NJsonSchema.dll assembly to the current session.

Set-Location -Path $PSHOME
$AccType = Add-Type -AssemblyName *jsonschema* -PassThru

Set-Location uses the Path parameter to specify the $PSHOME variable. The variable references the PowerShell installation directory where the DLL file is located.

The $AccType variable stores an object created with the Add-Type cmdlet. Add-Type uses the AssemblyName parameter to specify the name of the assembly. The asterisk ( * ) wildcard character allows you to get the correct assembly even when you aren't sure of the name or its spelling. The PassThru parameter generates objects that represent the classes that are added to the session.

Example 4: Call native Windows APIs

This example demonstrates how to call native Windows APIs in PowerShell. Add-Type uses the Platform Invoke (P/Invoke) mechanism to call a function in User32.dll from PowerShell. This example only works on computers running the Windows operating system.

$Signature = @"
[DllImport("user32.dll")]public static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);
"@

$ShowWindowAsync = Add-Type -MemberDefinition $Signature -Name "Win32ShowWindowAsync" -Namespace Win32Functions -PassThru

# Minimize the PowerShell console

$ShowWindowAsync::ShowWindowAsync((Get-Process -Id $pid).MainWindowHandle, 2)

# Restore the PowerShell console

$ShowWindowAsync::ShowWindowAsync((Get-Process -Id $Pid).MainWindowHandle, 4)

The $Signature variable stores the C# signature of the ShowWindowAsync function. To ensure that the resulting method is visible in a PowerShell session, the public keyword was added to the standard signature. For more information, see ShowWindowAsync function .

The $ShowWindowAsync variable stores the object created by the Add-Type PassThru parameter. The Add-Type cmdlet adds the ShowWindowAsync function to the PowerShell session as a static method. The command uses the MemberDefinition parameter to specify the method definition saved in the $Signature variable. The command uses the Name and Namespace parameters to specify a name and namespace for the class. The PassThru parameter generates an object that represents the types.

The new ShowWindowAsync static method is used in the commands to minimize and restore the PowerShell console. The method takes two parameters: the window handle, and an integer that specifies how the window is displayed.

To minimize the PowerShell console, ShowWindowAsync uses the Get-Process cmdlet with the $PID automatic variable to get the process that is hosting the current PowerShell session. Then it uses the MainWindowHandle property of the current process and a value of 2 , which represents the SW_MINIMIZE value.

To restore the window, ShowWindowAsync uses a value of 4 for the window position, which represents the SW_RESTORE value.

To maximize the window, use the value of 3 that represents SW_MAXIMIZE .

Parameters

-AssemblyName

-CompilerOptions

-IgnoreWarnings

-Language

-LiteralPath

-MemberDefinition

-Name

-Namespace

-OutputAssembly

-OutputType

-PassThru

-Path

-ReferencedAssemblies

-TypeDefinition

-UsingNamespace

Inputs

None

You can't pipe objects to this cmdlet.

Outputs

None

By default, this cmdlet returns no output.

Type

When you use the PassThru parameter, this cmdlet returns a System.Type object representing the new type.

Notes

The types that you add exist only in the current session. To use the types in all sessions, add them to your PowerShell profile. For more information about the profile, see about_Profiles .

Type names and namespaces must be unique within a session. You can't unload a type or change it. If you need to change the code for a type, you must change the name or start a new PowerShell session. Otherwise, the command fails.

In Windows PowerShell (version 5.1 and below), you need to use Add-Type for anything that isn't already loaded. Most commonly, this applies to assemblies found in the Global Assembly Cache (GAC). In PowerShell 6 and higher, there is no GAC, so PowerShell installs its own assemblies in $PSHome . These assemblies are automatically loaded on request, so there's no need to use Add-Type to load them. However, using Add-Type is still permitted to allow scripts to be implicitly compatible with any version of PowerShell.

Assemblies in the GAC can be loaded by type name, rather than by path. Loading assemblies from an arbitrary path requires Add-Type , since those assemblies cannot not be loaded automatically.

Related Links

• about_Profiles
• about_Quoting_Rules
• Add-Member
• New-Object
• OutputAssemblyType
• Platform Invoke (P/Invoke)
• Where-Object