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|
"""Python version compatibility support for minidom."""
# This module should only be imported using "import *".
#
# The following names are defined:
#
# isinstance -- version of the isinstance() function that accepts
# tuples as the second parameter regardless of the
# Python version
#
# NodeList -- lightest possible NodeList implementation
#
# EmptyNodeList -- lightest possible NodeList that is guarateed to
# remain empty (immutable)
#
# StringTypes -- tuple of defined string types
#
# GetattrMagic -- base class used to make _get_<attr> be magically
# invoked when available
# defproperty -- function used in conjunction with GetattrMagic;
# using these together is needed to make them work
# as efficiently as possible in both Python 2.2+
# and older versions. For example:
#
# class MyClass(GetattrMagic):
# def _get_myattr(self):
# return something
#
# defproperty(MyClass, "myattr",
# "return some value")
#
# For Python 2.2 and newer, this will construct a
# property object on the class, which avoids
# needing to override __getattr__(). It will only
# work for read-only attributes.
#
# For older versions of Python, inheriting from
# GetattrMagic will use the traditional
# __getattr__() hackery to achieve the same effect,
# but less efficiently.
#
# defproperty() should be used for each version of
# the relevant _get_<property>() function.
#
# NewStyle -- base class to cause __slots__ to be honored in
# the new world
#
# True, False -- only for Python 2.2 and earlier
__all__ = ["NodeList", "EmptyNodeList", "NewStyle",
"StringTypes", "defproperty", "GetattrMagic"]
import xml.dom
try:
unicode
except NameError:
StringTypes = type(''),
else:
StringTypes = type(''), type(unicode(''))
# define True and False only if not defined as built-ins
try:
True
except NameError:
True = 1
False = 0
__all__.extend(["True", "False"])
try:
isinstance('', StringTypes)
except TypeError:
#
# Wrap isinstance() to make it compatible with the version in
# Python 2.2 and newer.
#
_isinstance = isinstance
def isinstance(obj, type_or_seq):
try:
return _isinstance(obj, type_or_seq)
except TypeError:
for t in type_or_seq:
if _isinstance(obj, t):
return 1
return 0
__all__.append("isinstance")
if list is type([]):
class NodeList(list):
__slots__ = ()
def item(self, index):
if 0 <= index < len(self):
return self[index]
def _get_length(self):
return len(self)
def _set_length(self, value):
raise xml.dom.NoModificationAllowedErr(
"attempt to modify read-only attribute 'length'")
length = property(_get_length, _set_length,
doc="The number of nodes in the NodeList.")
def __getstate__(self):
return list(self)
def __setstate__(self, state):
self[:] = state
class EmptyNodeList(tuple):
__slots__ = ()
def __add__(self, other):
NL = NodeList()
NL.extend(other)
return NL
def __radd__(self, other):
NL = NodeList()
NL.extend(other)
return NL
def item(self, index):
return None
def _get_length(self):
return 0
def _set_length(self, value):
raise xml.dom.NoModificationAllowedErr(
"attempt to modify read-only attribute 'length'")
length = property(_get_length, _set_length,
doc="The number of nodes in the NodeList.")
else:
def NodeList():
return []
def EmptyNodeList():
return []
try:
property
except NameError:
def defproperty(klass, name, doc):
# taken care of by the base __getattr__()
pass
class GetattrMagic:
def __getattr__(self, key):
if key.startswith("_"):
raise AttributeError, key
try:
get = getattr(self, "_get_" + key)
except AttributeError:
raise AttributeError, key
return get()
class NewStyle:
pass
else:
def defproperty(klass, name, doc):
get = getattr(klass, ("_get_" + name)).im_func
def set(self, value, name=name):
raise xml.dom.NoModificationAllowedErr(
"attempt to modify read-only attribute " + repr(name))
assert not hasattr(klass, "_set_" + name), \
"expected not to find _set_" + name
prop = property(get, set, doc=doc)
setattr(klass, name, prop)
class GetattrMagic:
pass
NewStyle = object
|
