UseProcessBlockForPipelineCommand.md

UseProcessBlockForPipelineCommand

Severity Level: Warning

Description

Functions that support pipeline input should always handle parameter input in a process block. Unexpected behavior can result if input is handled directly in the body of a function where parameters declare pipeline support.

Example

Wrong

Function Get-Number
{
	[CmdletBinding()]
	Param(
		[Parameter(ValueFromPipeline)]
		[int]
		$Number
	)
	
	$Number
}

Result

PS C:\> 1..5 | Get-Number
5

Correct

Function Get-Number
{
	[CmdletBinding()]
	Param(
		[Parameter(ValueFromPipeline)]
		[int]
		$Number
	)
	
	process
	{
		$Number
	}
}

Result

PS C:\> 1..5 | Get-Number
1
2
3
4
5