invoke-environment.ps1

function Invoke-Environment {
# Source: http://stackoverflow.com/a/4385011/2608
# and https://github.com/nightroman/PowerShelf/blob/master/Invoke-Environment.ps1
    param
    (
	    [Parameter(Mandatory=1)][string]$Command,
	    [switch]$Output,
	    [switch]$Force
    )
    $stream = if ($Output) { ($temp = [IO.Path]::GetTempFileName()) } else { 'nul' }
    $operator = if ($Force) {'&'} else {'&&'}
    foreach($_ in cmd /c " $Command > `"$stream`" 2>&1 $operator SET") {
	    if ($_ -match '^([^=]+)=(.*)') {
		    [System.Environment]::SetEnvironmentVariable($matches[1], $matches[2])
	    }
    }
    if ($Output) {
	    Get-Content -LiteralPath $temp
	    Remove-Item -LiteralPath $temp
    }
}
# Configures the environment as per the VS Developer Command Prompt.
function As-VSPrompt {
    # VS 2013
    Invoke-Environment '"%VS120COMNTOOLS%\vsvars32.bat"'
}