Why doesn't $hash.key syntax work inside the ExpandString method?

Question

The following Powershell script demonstrates the issue:

$hash = @{\'a\' = 1; \'b\' = 2}
Write-Host $hash[\'a\']        # => 1
Write-Host $hash.a                   


        

Answer 1

The ExpandString api is not exactly meant for use from PowerShell scripts, it was added more for C# code. It's still a bug that your example doesn't work (and I think it's been fixed in V4), but it does mean there is a workaround - one that I recommend for general use.

Double quoted strings effectively (but not literally) call ExpandString. So the following should be equivalent:

$ExecutionContext.InvokeCommand.ExpandString('$($hash.a)')
"$($hash.a)"