[Tutor] Borg di borg di borg (or: Swedish chef)

[Albert-Jan Roskam]

Hi Pythonistas,

I have three classes, Generic, Test and Test2. Generic contains a load method that loads a file. This may only be done once, as a file_read_open error is returned if the file is open already and an attempt is made to re-open it. The file may be opened from Test or Test2. After a lot of playing with a "counter" class variable, I realized this may be a legitimate use case for the Borg pattern (http://code.activestate.com/recipes/66531). Is the code below the right way to apply the Borg pattern?


somefile = "/home/albertjan/Desktop/somefile.txt"

class Borg(object):

    counter = 0
    _state = {}

    def __init__(self):
        self.__dict__ = self._state

class Generic(Borg):
    
    def __init__(self):
        super(Generic, self).__init__()
        self.loaded = self.load()
        print "@state", Borg._state
        print self.loaded
        
    def load(self):
        """ Only one file at a time may be opened, or else
        there will be an open-read error"""
        Borg.counter += 1
        return open(somefile)

class Test(Generic):
    
    def __init__(self):
        if Borg.counter == 0:
            self.theFile = Generic().load()
        self.theFile = Borg._state["loaded"]
        print self.theFile

class Test2(Generic):

    def __init__(self):
        if Borg.counter == 0:
            self.theFile = Generic().load()       
        self.theFile = Borg._state["loaded"]
        print "---", self.theFile
        print Borg.counter
        

b2 = Test2()
b1 = Test()


Thank you in advance!

Regards,
Albert-Jan


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All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a 
fresh water system, and public health, what have the Romans ever done for us?
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