[Tutor] class instance with identity crisis

[Kent Johnson]

A couple of ideas:

You could have dry() return the new weapon:
   def dry(self):
     return Prune()

then the client code would be
weapon = weapon.dry()


You could have the weapon encapsulate another object and delegate to it.

Finally, you actually can change the class of an object just by assigning to self.__class__:
  >>> class A:
  ...   def show(self):
  ...     print "I'm an A"
  ...
  >>> class B:
  ...   def show(self):
  ...     print "I'm a B"
  ...
  >>> a=A()
  >>> a.__class__
<class __main__.A at 0x008CE750>
  >>> a.show()
I'm an A
  >>> a.__class__ = B
  >>> type(a)
<type 'instance'>
  >>> a.show()
I'm a B

So if you change
   self = Prune()
to
   self.__class__ = Prune

I think you will get the behaviour you are looking for.

I would look for another way to solve your problem, though - I agree with Pierre that this is likely 
to be confusing.

Kent

Barnaby Scott wrote:
> This is probably a very easy question, and one that I was shocked to find I
> was stuck on, having thought I understood classes!
> 
> I was wondering how you can get an instance of a class to change itself into
> something else (given certain circumstances), but doing so from within a
> method. So:
> 
> class Damson:
>     def __str__(self):
>         return 'damson'
> 
>     def dry(self):
>         self = Prune()
> 
> class Prune:
>     def __str__(self):
>         return 'prune'
> 
> weapon = Damson()
> weapon.dry()
> print weapon
> 
> All the old hands will of course know this will produce the output
> 
> damson
> 
> but something in me suggests it should produce
> 
> prune
> 
> After all, 'self' refers to the instance 'weapon'.
> 
> Obviously one could reassign weapon to a Prune outside the class definition,
> but I was hoping to write something in which, given certain circustances
> arising, the instance would change itself into something else.
> 
> Time to go back to school!
> 
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