PowerShell pass by reference not working for me

问题

I'm trying to make a simple swap function in PowerShell, but passing by reference doesn't seem to work for me.

function swap ([ref]$object1, [ref]$object2){
  $tmp = $object1.value
  $object1.value = $object2.value
  $object2.value = $tmp
}

$a = 1
$b = 2
$a, $b
swap ([ref]$a) ,([ref]$b)
$a, $b

This SHOULD work, but no...

Output:
    1
    2
    1
    2

What did I do wrong?

回答1:

Call like this:

swap ([ref]$a) ([ref]$b)

The mistake of using , is described in the Common Gotchas for PowerShell here on Stack Overflow.

回答2:

By the way, PowerShell has a special syntax to swap values, and there isn't a need to use $tmp:

$a,$b = $b,$a

回答3:

Firstly, you're calling it wrong. Putting a comma in the call to swap means you're passing an array of them to objects as the first parameter. If you were to correct it...

swap ([ref]$a) ([ref]$b)

...it would then work.

来源：https://stackoverflow.com/questions/7149783/powershell-pass-by-reference-not-working-for-me