> Behalf Of Manuel Bleichner
> In a module I have a huge number of classes of the form:
>
> class A(object):
> connected_to = [B, C]
> <other attributes...>
>
> class B(object)
> connected_to = [C]
> <other attributes...>
>
> class C(object)
> connected_to = [A]
> <other attributes...>
>
> As you see, classes A and B reference classes that are not
> yet defined when the class is being defined.
> It will raise a NameError: 'B'.
How about a connection broker?
Simple example:
#############################
connections = {}
def Register( obj ):
try:
connections[obj.name]['obj'] = obj
except KeyError:
connections[obj.name] = { 'obj' : obj, 'connected_to' : [] }
def ConnectTo( objname, obj ):
try:
connections[objname]['connected_to'].append( obj )
except KeyError:
connections[objname] = { 'obj' : None, 'connected_to' :
[obj] }
class ConnectionObject:
def __str__(self):
return self.name
class A(ConnectionObject):
def __init__(self):
self.name = 'A'
Register( self )
ConnectTo( 'B', self )
class B(ConnectionObject):
def __init__(self):
self.name = 'B'
Register( self )
ConnectTo( 'A', self )
ConnectTo( 'C', self )
class C(ConnectionObject):
def __init__(self):
self.name = 'C'
Register( self )
ConnectTo( 'A', self )
a = A()
b = B()
c = C()
for (key, val) in connections.iteritems():
print 'object: %s (%s)' % ( key, val['obj'] )
str_vals = []
for obj in val['connected_to']:
str_vals.append( str( obj ) )
print '\tconnections from:', str_vals
#############################
Output:
object: A (A)
connections from: ['B', 'C']
object: C (C)
connections from: ['B']
object: B (B)
connections from: ['A']
object: D (None)
connections from: ['C']
Regards,
Ryan Ginstrom
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