Path: csiph.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
From: Tony van der Hoff <tony@vanderhoff.org>
Newsgroups: comp.lang.python
Subject: Accessing container's methods
Date: Mon, 7 Dec 2015 18:10:10 +0000
Lines: 61
Message-ID: <dcm0c2Fi2ktU1@mid.individual.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Trace: individual.net PxV0aFi9cwzyxRxGnTmHNw6mnf+NMtp/W9Do9kvMTSdjwUGOlw
Cancel-Lock: sha1:7QYDgrjkcfm6KQG1FD7zfYXHuo4=
X-Mozilla-News-Host: news://news.individual.net:119
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.4.0
Xref: csiph.com comp.lang.python:100096

Hi,

I have a class A, containing embedded embedded classes, which need to 
access methods from A.
.
A highly contrived example, where I'm setting up an outer class in a 
Has-a relationship, containing a number of Actors. The inner class needs 
to access a method of the outer class; here the method get_name.

I don't really want to make Actor a sub-class (is-a; it isn't) of Monty; 
that would raise all sorts of other problems.

Can anyone please advise me on how to achieve this magic?

# define the outer class
class Monty:
   def __init__( self, names ):
     self.actors = []

     i = 0
     for n in names:
       self.actors.append( Actor( n, i ) )
       i += 1	# here is a case for python supporting post-increment!

   def count_actors( self ):
     return len( self.actors )

   def list_actors( self ):
     h=[]
     for n in self.actors:
       h.append( n.get_name() )
     return h

# define the inner class
class Actor:
   def __init__ ( self, name, id ):
     self.name = name
     self.id = id

   def get_name( self ):

     # and here lies the problem;
     # AttributeError: Actor instance has no attribute 'count_actors'
     # how do I access the method in the enclosing class
     txt = "I'm Actor {} Number {} of {}".\
              format(  self.name, self.id, self.count_actors() )

     # this works, of course
     #txt = "I'm Actor \"{}\"; Number {}.  ".\
		format( self.name, self.id )

     return txt

if __name__ == '__main__':
   o = Monty( ["Cleese", "Idle", "Palin" ] )
   print "number: ",o.count_actors()
   a = o.list_actors()
   for l in a:
     print l

Thanks, Tony