On 02/23/2012 12:04 PM, Holger Joukl wrote:
Hi,
I'm trying to instrument a wrapped class with custom __setattr__
mechanics:
.def("__setattr__",&MyExtensionClass::setattr)
How can I call the base class __setattr__ from within setattr and not run
into infinite recursion?
I.e. the analogon in C++ to
class Foo(object):
... def __setattr__(self, attr, value):
... print "custom __setattr__"
... object.__setattr__(self, attr, value)
...
foo = Foo()
foo.x = 23
custom __setattr__
foo.x
23
To actually write to my instance dict I currently do
PyObject* __dict__ = PyObject_GetAttrString(m_self, const_cast<char*>
("__dict__"));
PyDict_SetItemString(__dict__, name, value.ptr());
inside MyExtensionClass::setattr (where m_self is PyObj*)
Is there a better way?
Everything I can think of (e.g. extract the base class from __bases__[0]
and call its setattr) is functionally equivalent and not any prettier.
On a sidenote, I initially thought I could wrap the __dict__ in bp::dict()
to
use its nice Python-like API for item assignment but this seems to always
make a copy of the __dict__.
I.e something like
bp::dict bp_dict(__dict__);
bp_dict[name] = value;
won't work.
The trick is to do:
bp::dict bp_dict = bp::extract<bp::dict>(__dict__);
bp_dict[name] = value;
Just calling the bp::dict invokes Python's dict constructor, which does
a copy.
Jim
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