String interpolation of hashtable values in PowerShell

I've got a hashtable:

$hash = @{ First = 'Al'; Last = 'Bundy' }

I know that I can do this:

Write-Host "Computer name is ${env:COMPUTERNAME}"

So I was hoping to do this:

Write-Host "Hello, ${hash.First} ${hash.Last}."

...but I get this:

Hello,  .

How do I reference hash table members in string interpolation?

Write-Host "Hello, $($hash.First) $($hash.Last)."

"Hello, {0} {1}." -f $hash["First"] , $hash["Last"]

With the addition of a small function, you can be a bit more generic, if you wish. Watch out, though, you're executing potentially untrusted code in the $template string.

Function Format-String ($template) 
{
    # Set all unbound variables (@args) in the local context
    while (($key, $val, $args) = $args) { Set-Variable $key $val }
    $ExecutionContext.InvokeCommand.ExpandString($template)
}

# Make sure to use single-quotes to avoid expansion before the call.
Write-Host (Format-String 'Hello, $First $Last' @hash)

# You have to escape embedded quotes, too, at least in PoSh v2
Write-Host (Format-String 'Hello, `"$First`" $Last' @hash)

String interpolation of hashtable values in PowerShell

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