Advanced Windows PowerShell Scripting Video Training

Advanced Windows PowerShell Scripting Video Training
Advanced Windows PowerShell Scripting Video Training

Thursday, October 13, 2016

Avoid Displaying Information

When teaching PowerShell, I use Write-Host often just to display what is going on.  It may be to show the result of an IF or SWITCH construct.  Maybe to let us know that a value incremented.  In practice, I avoid placing text on the screen unless the user specifically asks for it. Write-Host places information directly onto the screen.  Write-Verbose and Write-Information places information in a data stream that eventually ends up on your screen.  This is bad for a few reasons.

First of all, the extra screen candy can be frustrating to watch.  Second, it takes time to write anything to the screen.  This is never good.  You should only display information if necessary and give the user a chance to suppress that information.  I decided to do a little test between Write-Host, Write-Verbose, Write-Information, and displaying nothing.  The code below loops 100 times for each command and again where nothing is performed in the loop.

Function Test-DisplayHost
{
    For($X = 0 ; $X -lt 100 ;$X++)
    {
        Write-Host "Write-Host $X" -ForegroundColor green
    }
}

Function Test-DisplayVerbose
{
    For($X = 0 ; $X -lt 100 ;$X++)
    {
        Write-Verbose "Write-Verbose $X" -Verbose
    }
}

Function Test-DisplayInformation
{
    For($X = 0 ; $X -lt 100 ;$X++)
    {
        Write-Information "Write-Information $X" -InformationAction Continue
    }
}

Function Test-NoDisplay
{
    For($X = 0 ; $X -lt 100 ;$X++)
    {
      
    }
}

Write-Host "Testing Write-Host" -ForegroundColor Cyan
$WriteHost = Measure-Command -Expression {
    Test-DisplayHost

}

Write-Host "Testing Write-Information" -ForegroundColor Cyan
$WriteVerbose = Measure-Command -Expression {
    Test-DisplayVerbose

}

Write-Host "Testing Write-Information" -ForegroundColor Cyan
$WriteInformation = Measure-Command -Expression {
    Test-DisplayInformation

}

Write-Host "Testing Nothing" -ForegroundColor Cyan
$WriteNoting = Measure-Command -Expression {
    Test-NoDisplay

}

Write-Host "Write-Host        | $($WriteHost.Ticks)"
Write-Host "Write-Verbose     | $($WriteVerbose.Ticks)"
Write-Host "Write-Information | $($WriteInformation.Ticks)"
Write-Host "Write nothing     | $($WriteNoting.Ticks)"

Here is the final output:

Write-Host        | 1167467
Write-Verbose     | 400858
Write-Information | 599326
Write nothing     | 6445

Two things that I took note of when running this code multiple times. The first is Write-Host always took longer.  The second, not displaying anything is always faster. 

The lessons learned here is to use Write-Verbose and Write-Information.  This allows the user to call the extra screen candy if they want, and suppress it when they do not.  Remember that Write-Information is a PowerShell 5 cmdlet.


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