Powershell utilities for locating Python installations from Windows registry

python_locator.ps1

function Get-DefaultPython {

    $pythonVersions = (get-item HKCU:\Software\Python\PythonCore).GetSubKeyNames()
    $pythons = $pythonVersions  | %{Get-ItemProperty "hkcu:\Software\Python\PythonCore\$_"}

    # favor most recent version of Python and x64 version of Python over x86 version
    
    $x64Pythons = $pythons | ?{$_.SysArchitecture.StartsWith("64")} | Sort-Object -Property SysVersion -Descending
    if ($x64Pythons.Length -gt 0)
    {
        return $x64Pythons[0].PSChildName
    }
    
    $x86Pythons = $pythons | ?{$_.SysArchitecture.StartsWith("32")} | Sort-Object -Property SysVersion -Descending
    if ($x86Pythons.Length -gt 0)
    {
        return $x86Pythons[0].PSChildName
    }

    throw "Python not installed"
}

function Get-PythonFolder {
[CmdletBinding()]
Param()
DynamicParam 
{
    $pythonVersions = (get-item HKCU:\Software\Python\PythonCore).GetSubKeyNames()

    # from https://github.com/beatcracker/Powershell-Misc/blob/master/New-DynamicParameter.ps1
    New-DynamicParameter -Name version -ValidateSet $pythonVersions -Type ([string])
}
process 
{
    $version = $PSBoundParameters["version"]
    if ($version -eq $null)
    {
        $version = Get-DefaultPython
    }
    (Get-ItemProperty "hkcu:\Software\Python\PythonCore\$version\InstallPath")."(default)";
}
}