This coding style bad practise?

[Martin P. Hellwig]

Hi all,

I created a class which creates a relative unique id string, now my 
program just works fine and as expected but somehow I get the feeling 
that I misused the __repr__ since I guess people expect to 'execute' a 
function in an instance instead of using it's representation string of 
the instance itself, could you elaborate whether you find this bad 
practice and if yes what would have been a better way to do it?

TIA

----- script -----
> import string
> import time
> 
> class IDGenerator(object):
>     """(serverID,subversion_length)
>     Create an ID from the server name, datetimestamp and version number.
>     Calling the instance returns the ID using the __repr__ class function
>     
>     Example usage:
>     >>> id = idgen('01',4)
>     >>> id
>     01_20060424_151903_1
>     >>> id
>     01_20060424_151905_2
>     >>> id
>     01_20060424_151905_3
>     >>> id
>     01_20060424_151906_4
>     >>> id
>     01_20060424_151907_1
>     >>>
>     >>> id = idgen(04,100)
>     >>> id
>     4_20060424_152043_001
>     
>     """
> 
>     def __init__(self,serverID,subversion_length):
>         self.ID = str(serverID)
>         self.length = int(subversion_length)
>         fill_length = len(str(self.length))
>         
>         def fill(number):
>             return(string.zfill(number,fill_length))
>         self.fill = fill
>             
> 
>     def __repr__(self):
>         # If the subversion length has been reached or the generator has not
>         # been defined, (re)define it, otherwise return the next value of the
>         # subversion.
>         try:
>             return_value = self.range_gen.next()
> 
>         except:
>             self.range_gen = ( number for number in range(1,self.length+1) )
>             return_value = self.range_gen.next()
> 
>         # Create the version stamp.
>         return_value = self.ID +\
>                        time.strftime("_%Y%m%d_%H%M%S_",time.gmtime())+\
>                        self.fill(return_value)
>         
>         # And return it.
>         return(return_value)
----- script -----

-- 
mph