about_Script_Blocks

TOPIC
	about_Script_Blocks

SHORT DESCRIPTION
	Defines what a script block is and explains how to use script blocks in 
	the Windows PowerShell programming language.


LONG DESCRIPTION
	In the Windows PowerShell programming language, a script block is a 
	collection of statements or expressions that can be used as a single unit. 
	A script block can accept arguments and return values.

	Syntactically, a script block is a statement list in braces, as shown in 
	the following syntax:


		{<statement list>}


	A script block returns the output of all the commands in the script block, 
	either as a single object or as an array.

	Like functions, a script block can include parameters. Use the Param 
	keyword to assign named parameters, as shown in the following syntax: 


		{
			param ([type]$parameter1 [,[type]$parameter2])
			<statement list>
	}


	In a script block, unlike a function, you cannot specify parameters outside 
	the braces.


	Like functions, script blocks can include the DynamicParam, Begin, Process, 
	and End keywords. For more information, see about_Functions and 
	about_Functions_Advanced.


  Using Script Blocks

	A script block is an instance of a Microsoft .NET Framework type 
	(System.Management.Automation.ScriptBlock). Commands can have script 
	block parameter values. For example, the Invoke-Command cmdlet has a 
	ScriptBlock parameter that takes a script block value, as shown in this 
	example:


		C:\PS> invoke-command -scriptblock  { get-process }
		Handles  NPM(K)	PM(K)	 WS(K) VM(M)   CPU(s)	 Id ProcessName
		-------  ------	-----	 ----- -----   ------	 -- -----------		
			999	28	39100	 45020   262	15.88   1844 communicator
			721	28	32696	 36536   222	20.84   4028 explorer   
		. . .		 


	The script block that is used as a value can be more complicated, as 
	shown in the following example:


		C:\PS> invoke-command -scriptblock { param ($uu = "Parameter"); 
			"$uu assigned." }  
		Parameter assigned.


	The script block in the preceding example uses the Param keyword to 
	create a parameter that has a default value. The following example uses 
	the Args parameter of the Invoke-Command cmdlet to assign a different 
	value to the parameter:


		C:\PS> invoke-command -scriptblock {param ($uu = "Parameter"); 
			"$uu assigned."} -args "Other value"
		Other value assigned.


	You can assign a script block to a variable, as shown in the following 
	example:


		C:\PS> $a = {param ($uu = "Parameter"); "$uu assigned."}


	You can use the variable with a cmdlet such as Invoke-Command, as shown 
	in the following example:


		C:\PS> invoke-command -scriptblock $a -args "Other value"
		Other value assigned.


	You can run a script block that is assigned to a variable by using the 
	call operator (&), as shown in the following example:


		C:\PS> &$a 
		Parameter assigned.


	You can also provide a parameter to the script block, as shown in the 
	following example:


		C:\PS> &$a "Other value"
		Other value assigned.


	If you want to assign the value that is created by a script block to a 
	variable, use the call operator to run the script block directly, as 
	shown in the following example:


		C:\PS> $a = &{param ($uu = "Parameter"); "$uu assigned."}
		C:\PS> $a
		Parameter assigned.


	For more information about the call operator, see about_Operators.


SEE ALSO
	about_Functions
	about_Functions_Advanced
	about_Operators