Demonstration of -Begin {} and -End {} vs. Pipeline Flow of Control of Beforehand and Afterward Utility Functions

beforehand-afterward.ps1

function Beforehand {
    param(
        [Parameter(Mandatory,ValueFromPipeline)]
        $InputObject,

        [Parameter(Mandatory,Position=1)]
        [scriptblock]
        $ScriptBlock
    )
    begin   { . $ScriptBlock }
    process { ,$InputObject  }
}

function Afterward {
    param(
        [Parameter(Mandatory,ValueFromPipeline)]
        $InputObject,

        [Parameter(Mandatory,Position=1)]
        [scriptblock]
        $ScriptBlock
    )
    process { ,$InputObject  }
    end     { . $ScriptBlock }
}

"`n## Output from begin"


"`n### -Begin -End"

'a','b' | 
    % -Begin {'begin1'} -Process {"process1$_"} -End {'end1'} |
    % -Begin {'begin2'} -Process {"process2$_"} -End {'end2'}

# begin2
# process2begin1
# process2process1a
# process2process1b
# process2end1
# end2


"`n### Beforehand Afterward"

'a','b' | 
    Beforehand {'begin1'} | % {"process1$_"} | Afterward {'end1'} |
    Beforehand {'begin2'} | % {"process2$_"} | Afterward {'end2'}

# process2begin2
# process2process1begin1
# process2process1a
# process2process1b
# process2end1
# end2

"`n## No Output from begin"


"`n### -Begin -End"

'a','b' | 
    % -Begin {Write-Host 'begin1'} -Process {"process1$_"} -End {'end1'} |
    % -Begin {Write-Host 'begin2'} -Process {"process2$_"} -End {'end2'}

# begin1
# begin2
# process2process1a
# process2process1b
# process2end1
# end2


"`n### Beforehand Afterward"

'a','b' | 
    Beforehand {Write-Host 'begin1'} | % {"process1$_"} | Afterward {'end1'} |
    Beforehand {Write-Host 'begin2'} | % {"process2$_"} | Afterward {'end2'}

# begin1
# begin2
# process2process1a
# process2process1b
# process2end1
# end2