Prefix Assignment Operator in Powershell

So powershell (and most languages) have an assignment by addition operator that works with string by adding the new string to the tail of the original

For example this:

$targetPath += "\*"

Will do the same thing as this:

$targetPath = "$targetPath\*"

Is there an operator that can do the same thing, but by prefixing the current string?

Of course, I can do the following, but I'm looking for something slightly terser

$targetPath = "Microsoft.PowerShell.Core\FileSystem::$targetPath"

Answer

August 11, 2015

Mathias R. Jessen

PowerShell doesn't - but the .NET [string] type has the Insert() method :

PS C:\> "abc".Insert(0,"xyz")
xyzabc

You still can't shortcut the assigment though, it would become:

$targetPath = $targetPath.Insert(0,'Microsoft.PowerShell.Core\FileSystem::')

Alternatively, create a function that does it for you:

function Prepend-StringVariable {
    param(
        [string]$VariableName,
        [string]$Prefix
    )

    # Scope:1 refers to the immediate parent scope, ie. the caller
    $var = Get-Variable -Name $VariableName -Scope 1
    if($var.Value -is [string]){
        $var.Value = "{0}{1}" -f $Prefix,$var.Value
    }
}

And in use:

PS C:\> $targetPath = "C:\Somewhere"
PS C:\> Prepend-String targetPath "Microsoft.PowerShell.Core\FileSystem::"
PS C:\> $targetPath
Microsoft.PowerShell.Core\FileSystem::C:\Somewhere

Although I'd generally recommend against this pattern (writing back to variables in ancestral scopes unless necessary)