super not working in __del__ ?

[Fredrik Lundh]

Christopher J. Bottaro wrote:

>I get this exception when I run the following code:
>
> Exception exceptions.TypeError: 'super() argument 1 must be type, not None'
> in <bound method Txrposdn.__del__ of <__main__.Txrposdn object at
> 0xf6f7118c>> ignored

reading the documentation never hurts:

    http://docs.python.org/ref/customization.html

    "Warning: Due to the precarious circumstances under which __del__()
    methods are invoked, exceptions that occur during their execution are
    ignored, and a warning is printed to sys.stderr instead. Also, when
    __del__() is invoked in response to a module being deleted (e.g.,
    when execution of the program is done), other globals referenced by
    the __del__() method may already have been deleted. For this
    reason, __del__() methods should do the absolute minimum needed
    to maintain external invariants."

in this case,

  def __del__(self):
    super(self.__class__, self).__del__()

should do the trick.

in other cases, you may have to store references to important globals to class
or instance variables, or in bound arguments:

  def __del__(self, name=name):
    name(...)

or you could just wrap the cleanup in a try/except clause, since this only happens
when the interpreter is shutting down.

for cleanup details, see:

    http://www.python.org/doc/essays/cleanup.html

</F>