On 12/7/2015 1:10 PM, Tony van der Hoff wrote:
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!
This is actually a case for using enumerate:
for i, name in enumerate(names):
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
return list(self.actors) # or perhaps even faster
return self.actors[:]
# define the inner class
class Actor:
def __init__ ( self, name, id ):
self.name = name
self.id = id
Tkinter, and I presume tk, works by creating circular references.
widgets get a reference to a master widget, and container get a
reference to widgets that are placed (or packed or gridded) therein.
Widgets have an explicit .destroy method (inherited from tcl/tk) to undo
the circularity. It works, but it is not completely without problems.
--
Terry Jan Reedy
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