Accessing overridden __builtin__s?

bruno at modulix onurb at xiludom.gro
Tue Mar 14 10:27:06 CET 2006

garyjefferson123 at wrote:
> I'm having a scoping problem.  I have a module called SpecialFile,

The convention is to use all_lowercase names for modules, and CamelCase
for classes.

> which defines:
> def open(fname, mode):
>   return SpecialFile(fname, mode)

This shadows the builtin open() function.

> class SpecialFile:

Old-style classes are deprecated, please use new-style classes

>   def __init__(self, fname, mode):
>     self.f = open(fname, mode)
>     ...
> The problem, if it isn't obvioius, is that the open() call in __init__
> no longer refers to the builtin open(), but to the module open().  So,
> if I do:
> f =, mode)
> I get infinite recursion.
> How do I tell my class that I want to refer to the __builtin__ open(),
> and not the one defined in the module?

You can use Steven's solution, or keep a reference to the builtin open()
function before defining your own open() function:

builtin_open = open
def open(fname, mode):
  return SpecialFile(fname, mode):

class SpecialFile(object):
  def __init__(self, fname, mode):
    self.f = builtin_open(fname, mode)

bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in 'onurb at xiludom.gro'.split('@')])"

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