Null operators demo for RTPSUG 2020-03-04

RTPSUG-Null.ps1

break

#region Null Coalescing Operator (??)

# Returns value on the left if it's not null
# Otherwise the right had side is evaluated and returned

$Left ?? $Right


#region The Old Way

$TheThing = $null

if ($null -eq $TheThing) {
	"Nope, it wasn't there!"
} else {
	$TheThing
}

#endregion

#region The New Way

$TheThing = $null

(!$TheThing) ?? "Nope, it wasn't there!"

#endregion

#region And with a value assigned?

$TheThing = 'This is a value'

$TheThing ?? "Nope, it wasn't there!"

#endregion

#region Both Sides Can Be Evaluated

(Get-ChildItem -Path .\ -EA SilentlyContinue) ?? (Get-Date | Select-Object *)

#endregion

#endregion

#region Null Assignment Operator (??=)

# Assignes the value on the right, only if the left is null

#region The Old Way

$TheThing = $null

if ($null -eq $TheThing) {
	$TheThing = "Fallback Value"
}

$TheThing

#endregion

#region The New Way

$TheThing = $null

$TheThing ??= "Fallback Value"

$TheThing

#endregion

#region Existing Value

$TheThing = 'Existing Value'

$TheThing ??= "Fallback Value"

$TheThing

#endregion

#endregion

#region Experimental: Null Conditional Access (?. and ?[])

# Access members and index items on potentially null variables without errors

Get-ExperimentalFeature -Name PSNullConditionalOperators
Enable-ExperimentalFeature -Name PSNullConditionalOperators

#region Methods

$BitsService.Stop()

${BitsService}?.Stop()

#endregion

#region Index

$Users[0]

${Users}?[0]

#endregion

#region Combined

${Users}?[0]?.SamAccountName ?? 'Nothing'

#endregion

#endregion