#SOURCE: http://code.activestate.com/recipes/474070-creating-a-single-instance-application/

from win32event import CreateMutex
from win32api import CloseHandle, GetLastError
from winerror import ERROR_ALREADY_EXISTS

class Singleinstance:
    """ Limits application to single instance """

    def __init__(self):

        self.mutexname = "testmutex_{D0E858DF-985E-4907-B7FB-8D732C3FC3B9}"
        self.mutex = CreateMutex(None, False, self.mutexname)
        self.lasterror = GetLastError()
    
    def alreadyrunning(self):

        return (self.lasterror == ERROR_ALREADY_EXISTS)
        
    def __del__(self):

        if self.mutex:
            CloseHandle(self.mutex)