How to wrap a class's methods?

[Grant Edwards]

On 2005-02-17, Mathias Waack <M.Waack at gmx.de> wrote:

> How about using a delegator: 
>
> class Wrapper:
>   funcs = ("login", "list", "search")
>   def __init__(self, classobj):
>     self.__wrapped = classobj()
>   def __getattr__(self, attr):
>     if attr in Wrapper.funcs:
>       def f(*args):
>         f1 = getattr(self.__wrapped, attr)
>         s,r = f1(args)
>         if s != 'OK': raise NotOk((s,r))
>         return r
>       return f
>     # raise some exception here
> imap = Wrapper(imaplib.IMAP4_SSL)
>
> If you wrap all methods you can ignore the if-test.

I'm not, and the other methods should behave "normally":

class Wrapper:
  funcs = ("login", "list", "search")
  def __init__(self, classobj):
    self.__wrapped = classobj()
  def __getattr__(self, attr):
    if attr in Wrapper.funcs:
      def f(*args):
        f1 = getattr(self.__wrapped, attr)
        s,r = f1(args)
        if s != 'OK': raise NotOk((s,r))
        return r
    else:
      f = getattr(self.__wrapped, attr)
    return f

> PS: note that we're wrapping the instance's methods, not the class's
> methods!

You're right.

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