Powershell closures

As a follow up to the previous article, I needed to warn you (and me) about powershell closures. They didn’t work as i expected

	$Foo = 1
	Write-Host "I expect Foo to be 1: " $Foo
	function New-Closure {
	param([Scriptblock] $Expression, $Foo = 2)
	& $Expression
	}
	New-Closure -Expression {
	Write-Host "I expected Foo to be 1, but was 2: " $Foo
	}
	New-Closure -Expression {
	Write-Host "I expected Foo to be 1, and it is: " $Foo
	}.GetNewClosure()

view raw closure-demo.ps1 hosted with ❤ by GitHub

The confusion point for me was that $Foo can be changed by the invoker, unless we add the .GetNewClosure().

As in the previous article the parameter name $ResourceGroupName is very common, it’s best to always use the .GetNewClosure() on the ScriptBlock