TOPIC about_Types.ps1xml SHORT DESCRIPTION Explains how the Types.ps1xml files let you extend the Microsoft .NET Framework types of the objects that are used in Windows PowerShell. LONG DESCRIPTION The Types.ps1xml file in the Windows PowerShell installation directory ($pshome) is an XML-based text file that lets you add properties and methods to the objects that are used in Windows PowerShell. Windows PowerShell has a built-in Types.ps1xml file that adds several elements to the .NET Framework types, but you can create additional Types.ps1xml files to further extend the types. For example, by default, array objects (System.Array) have a Length property that lists the number of objects in the array. However, because the name "length" does not clearly describe the property, Windows PowerShell adds an alias property named "Count" that displays the same value. The following XML adds the Count property to the System.Array type. <Type> <Name>System.Array</Name> <Members> <AliasProperty> <Name>Count</Name> <ReferencedMemberName> Length </ReferencedMemberName> </AliasProperty> </Members> </Type> To get the new AliasProperty, use a Get-Member command on any array, as shown in the following example. Get-Member -inputobject (1,2,3,4) The command returns the following results. Name MemberType Definition ---- ---------- ---------- Count AliasProperty Count = Length Address Method System.Object& Address(Int32 ) Clone Method System.Object Clone() CopyTo Method System.Void CopyTo(Array array, Int32 index): Equals Method System.Boolean Equals(Object obj) Get Method System.Object Get(Int32 ) ... As a result, you can use either the Count property or the Length property of arrays in Windows PowerShell. For example: C:\PS> (1, 2, 3, 4).count 4 C:\PS> (1, 2, 3, 4).length 4 Creating New Types.ps1xml Files The .ps1xml files that are installed with Windows PowerShell are digitally signed to prevent tampering because the formatting can include script blocks. Therefore, to add a property or method to a .NET Framework type, create your own Types.ps1xml files, and then add them to your Windows PowerShell console. To create a new file, start by copying an existing Types.ps1xml file. The new file can have any name, but it must have a .ps1xml file name extension. You can place the new file in any directory that is accessible to Windows PowerShell, but it is useful to place the files in the Windows PowerShell installation directory ($pshome) or in a subdirectory of the installation directory. When you have saved the new file, use the Update-TypeData cmdlet to add the new file to your Windows PowerShell console. If you want your types to take precedence over the types that are defined in the built-in file, use the PrependData parameter of the Update-TypeData cmdlet. Update-TypeData affects only the current console. To make the change to all future consoles, export the console, or add the Update-TypeData command to your Windows PowerShell profile. Types.ps1xml and Add-Member The Types.ps1xml files add properties and methods to all the instances of the objects of the specified .NET Framework type in the affected Windows PowerShell console. However, if you need to add properties or methods only to one instance of an object, use the Add-Member cmdlet. For more information,see Add-Member. Example: Adding an Age Member to FileInfo Objects This example shows how to add an Age property to file objects (System.IO.FileInfo). The age of a file is the difference between its creation time and the current time in days. It is easiest to use the original Types.ps1xml file as a template for the new file. The following command copies the original file to a file called MyTypes.ps1xml in the $pshome directory. copy-item Types.ps1xml MyTypes.ps1xml Next, open the Types.ps1xml file in any XML or text editor, such as Notepad. Because the Age property is calculated by using a script block, find a <ScriptProperty> tag to use as a model for the new Age property. Copy the XML between the <Type> and </Type> tags of the code to create the script property. Then, delete the remainder of the file, except for the opening <?xml> and <Types> tags and the closing </Types> tag. You must also delete the digital signature to prevent errors. Begin with the model script property, such as the following script property, which was copied from the original Types.ps1xml file. <?xml version="1.0" encoding="utf-8" ?> <Types> <Type> <Name>System.Guid</Name> <Members> <ScriptProperty> <Name>Guid</Name> <GetScriptBlock>$this.ToString()</GetScriptBlock> </ScriptProperty> </Members> </Type> </Types> Then, change the name of the .NET Framework type, the name of the property, and the value of the script block to create an Age property for file objects. <?xml version="1.0" encoding="utf-8" ?> <Types> <Type> <Name>System.IO.FileInfo</Name> <Members> <ScriptProperty> <Name>Age</Name> <GetScriptBlock> ((get-date) - ($this.creationtime)).days </GetScriptBlock> </ScriptProperty> </Members> </Type> </Types> After you save the file and close it, use an Update-TypeData command, such as the following command, to add the new Types.ps1xml file to the current console. The command uses the PrependData parameter to place the new file in a higher precedence order than the original file. (For more information about Update-TypeData, see Update-TypeData.) update-typedata -prependpath $pshome\MyTypes.ps1xml To test the change, use a Get-ChildItem command to get the PowerShell.exe file in the $pshome directory, and then pipe the file to the Format-List cmdlet to list all of the properties of the file. As a result of the change, the Age property appears in the list. get-childitem $pshome\powershell.exe | format-list -property * PSPath : Microsoft.PowerShell.Core\FileSystem::C:\WINDOWS... PSParentPath : Microsoft.PowerShell.Core\FileSystem::C:\WINDOWS... PSChildName : powershell.exe PSDrive : C PSProvider : Microsoft.PowerShell.Core\FileSystem PSIsContainer : False Age : 16 VersionInfo : File: C:\WINDOWS\system32\WindowsPow... InternalName: POWERSHELL OriginalFilename: PowerShell.EXE ... You can also display the Age property of the file by using the following command. (get-childitem $pshome\powershell.exe).age 16 The XML in Types.ps1xml Files The <Types> tag encloses all of the types that are defined in the file. There should be only one pair of <Types> tags. Each .NET Framework type mentioned in the file should be represented by a pair of <Type> tags. The type tags must contain the following tags: <Name>: A pair of <Name> tags that enclose the name of the affected .NET Framework type. <Members>: A pair of <Members> tags that enclose the tags for the new properties and methods that are defined for the .NET Framework type. Any of the following member tags can be inside the <Members> tags. <AliasProperty>: Defines a new name for an existing property. The <AliasProperty> tag must have a pair of <Name> tags that specify the name of the new property and a pair of <ReferencedMemberName> tags that specify the existing property. For example, the Count alias property is an alias for the Length property of array objects. <Type> <Name>System.Array</Name> <Members> <AliasProperty> <Name>Count</Name> <ReferencedMemberName>Length</ReferencedMemberName> </AliasProperty> </Members> </Ty...
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