about_Functions_Advanced

TOPIC
	about_Functions_Advanced

SHORT DESCRIPTION
	Introduces advanced functions that act similar to cmdlets.

LONG DESCRIPTION
	Advanced functions allow you to write functions that can perform operations 
	that are similar to the operations you can perform with cmdlets. Advanced 
	functions are helpful when you want to quickly write a function without 
	having to write a compiled cmdlet using a Microsoft .NET Framework 
	language. These functions are also helpful when you want to restrict the
	functionality of a compiled cmdlet or when you want to write a function 
	that is similar to a compiled cmdlet.
 

	There is a difference between authoring a compiled cmdlet and an advanced
	function. Compiled cmdlets are .NET Framework classes that must be written
	in a .NET Framework language such as C#. In contrast, advanced functions 
	are written in the Windows PowerShell script language in the same way that
	other functions or script blocks are written.


	Advanced functions use the CmdletBinding attribute to identify them as 
	functions that act similar to cmdlets. The CmdletBinding attribute is 
	similar to the Cmdlet attribute that is used in compiled cmdlet classes to
	identify the class as a cmdlet. For more information about this attribute,
	see about_Functions_CmdletBindingAttribute.


	The following example shows a function that accepts a name and then prints
	a greeting using the supplied name. Also notice that this function defines
	a name that includes a verb (Send) and noun (Greeting) pair similar to the
	verb-noun pair of a compiled cmdlet. However, functions are not required 
	to have a verb-noun name. 


		function Send-Greeting
		{
		[CmdletBinding()]
		Param(
			[Parameter(Mandatory=$true)]
			[string] $Name
		)
		Process
		{
			write-host ("Hello " + $Name + "!")
	}
	}


	The parameters of the function are declared by using the Parameter 
	attribute. This attribute can be used alone, or it can be combined with 
	the Alias attribute or with several other parameter validation attributes.
	For more information about how to declare parameters (including dynamic
	parameters that are added at runtime), see
	about_Functions_Advanced_Parameters. 
 

	The actual work of the previous function is performed in the Process 
	block, which is equivalent to the ProcessingRecord method that is used by 
	compiled cmdlets to process the data that is passed to the cmdlet. This 
	block, along with the Begin and End blocks, is described in the 
	about_Functions_Advanced_Methods topic.


	Advanced functions differ from compiled cmdlets in the following ways: 

		- Advanced function parameter binding does not throw an exception when 
		an array of strings is bound to a Boolean parameter.

		- The ValidateSet attribute and the ValidatePattern attribute cannot 
		pass named parameters.

		- Advanced functions cannot be used in transactions.

   
SEE ALSO
	about_Functions_Advanced_CmdletBindingAttribute
	about_Functions_Advanced_Methods
	about_Functions_Advanced_Parameters 
	Windows PowerShell Cmdlets (http://go.microsoft.com/fwlink/?LinkID=135279)