virtualenv.py 文件源码

def get_installed_pythons():
        try:
            python_core = winreg.CreateKey(winreg.HKEY_LOCAL_MACHINE,
                                           "Software\\Python\\PythonCore")
        except WindowsError:
            # No registered Python installations
            return {}
        i = 0
        versions = []
        while True:
            try:
                versions.append(winreg.EnumKey(python_core, i))
                i = i + 1
            except WindowsError:
                break
        exes = dict()
        for ver in versions:
            try:
                path = winreg.QueryValue(python_core, "%s\\InstallPath" % ver)
            except WindowsError:
                continue
            exes[ver] = join(path, "python.exe")

        winreg.CloseKey(python_core)

        # Add the major versions
        # Sort the keys, then repeatedly update the major version entry
        # Last executable (i.e., highest version) wins with this approach
        for ver in sorted(exes):
            exes[ver[0]] = exes[ver]

        return exes