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Unified Diff: third_party/google-endpoints/future/builtins/newsuper.py

Issue 2666783008: Add google-endpoints to third_party/. (Closed)
Patch Set: Created 3 years, 11 months ago
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Index: third_party/google-endpoints/future/builtins/newsuper.py
diff --git a/third_party/google-endpoints/future/builtins/newsuper.py b/third_party/google-endpoints/future/builtins/newsuper.py
new file mode 100644
index 0000000000000000000000000000000000000000..a787f4bb9cb697f5b6861d4b67e0347f4683dc38
--- /dev/null
+++ b/third_party/google-endpoints/future/builtins/newsuper.py
@@ -0,0 +1,115 @@
+'''
+This module provides a newsuper() function in Python 2 that mimics the
+behaviour of super() in Python 3. It is designed to be used as follows:
+
+ from __future__ import division, absolute_import, print_function
+ from future.builtins import super
+
+And then, for example:
+
+ class VerboseList(list):
+ def append(self, item):
+ print('Adding an item')
+ super().append(item) # new simpler super() function
+
+Importing this module on Python 3 has no effect.
+
+This is based on (i.e. almost identical to) Ryan Kelly's magicsuper
+module here:
+
+ https://github.com/rfk/magicsuper.git
+
+Excerpts from Ryan's docstring:
+
+ "Of course, you can still explicitly pass in the arguments if you want
+ to do something strange. Sometimes you really do want that, e.g. to
+ skip over some classes in the method resolution order.
+
+ "How does it work? By inspecting the calling frame to determine the
+ function object being executed and the object on which it's being
+ called, and then walking the object's __mro__ chain to find out where
+ that function was defined. Yuck, but it seems to work..."
+'''
+
+from __future__ import absolute_import
+import sys
+from types import FunctionType
+
+from future.utils import PY3, PY26
+
+
+_builtin_super = super
+
+_SENTINEL = object()
+
+def newsuper(typ=_SENTINEL, type_or_obj=_SENTINEL, framedepth=1):
+ '''Like builtin super(), but capable of magic.
+
+ This acts just like the builtin super() function, but if called
+ without any arguments it attempts to infer them at runtime.
+ '''
+ # Infer the correct call if used without arguments.
+ if typ is _SENTINEL:
+ # We'll need to do some frame hacking.
+ f = sys._getframe(framedepth)
+
+ try:
+ # Get the function's first positional argument.
+ type_or_obj = f.f_locals[f.f_code.co_varnames[0]]
+ except (IndexError, KeyError,):
+ raise RuntimeError('super() used in a function with no args')
+
+ try:
+ # Get the MRO so we can crawl it.
+ mro = type_or_obj.__mro__
+ except (AttributeError, RuntimeError): # see issue #160
+ try:
+ mro = type_or_obj.__class__.__mro__
+ except AttributeError:
+ raise RuntimeError('super() used with a non-newstyle class')
+
+ # A ``for...else`` block? Yes! It's odd, but useful.
+ # If unfamiliar with for...else, see:
+ #
+ # http://psung.blogspot.com/2007/12/for-else-in-python.html
+ for typ in mro:
+ # Find the class that owns the currently-executing method.
+ for meth in typ.__dict__.values():
+ # Drill down through any wrappers to the underlying func.
+ # This handles e.g. classmethod() and staticmethod().
+ try:
+ while not isinstance(meth,FunctionType):
+ if isinstance(meth, property):
+ # Calling __get__ on the property will invoke
+ # user code which might throw exceptions or have
+ # side effects
+ meth = meth.fget
+ else:
+ try:
+ meth = meth.__func__
+ except AttributeError:
+ meth = meth.__get__(type_or_obj)
+ except (AttributeError, TypeError):
+ continue
+ if meth.func_code is f.f_code:
+ break # Aha! Found you.
+ else:
+ continue # Not found! Move onto the next class in MRO.
+ break # Found! Break out of the search loop.
+ else:
+ raise RuntimeError('super() called outside a method')
+
+ # Dispatch to builtin super().
+ if type_or_obj is not _SENTINEL:
+ return _builtin_super(typ, type_or_obj)
+ return _builtin_super(typ)
+
+
+def superm(*args, **kwds):
+ f = sys._getframe(1)
+ nm = f.f_code.co_name
+ return getattr(newsuper(framedepth=2),nm)(*args, **kwds)
+
+
+__all__ = ['newsuper']
+
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