Hi all,

The Python binding in libxml2 uses the following code for __repr__():

class xmlNode(xmlCore):
    def __init__(self, _obj=None):
        self._o = None
        xmlCore.__init__(self, _obj=_obj)

    def __repr__(self):
        return "<xmlNode (%s) object at 0x%x>" % (self.name, id (self))

With Python 2.3.4 I'm seeing warnings like the one below:
<frozen module libxml2>:2357: FutureWarning: %u/%o/%x/%X of negative int will return a signed string in Python 2.4 and up


I believe this is caused by the memory address having the sign bit set, causing builtin_id() to return a negative integer.

I grepped around in the Python standard library and found a rather awkward work-around that seems to be slowly propagating to various module using the "'%x' % id(self)" idiom:

Lib/asyncore.py:
        # On some systems (RH10) id() can be a negative number.
        # work around this.
        MAX = 2L*sys.maxint+1
        return '<%s at %#x>' % (' '.join(status), id(self)&MAX)


$ grep -r 'can be a negative number' *
Lib/asyncore.py: # On some systems (RH10) id() can be a negative number.
Lib/repr.py: # On some systems (RH10) id() can be a negative number.
Lib/tarfile.py: # On some systems (RH10) id() can be a negative number.
Lib/test/test_repr.py: # On some systems (RH10) id() can be a negative number.
Lib/xml/dom/minidom.py: # On some systems (RH10) id() can be a negative number.


There are many modules that do not have this work-around in Python 2.3.4.

Wouldn't it be more elegant to make builtin_id() return an unsigned long integer? Is the performance impact too great?

A long integer is used on platforms where SIZEOF_VOID_P > SIZEOF_LONG (most 64 bit platforms?), so all Python code must be prepared to handle it already...

Troels
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