[C++-sig] contained structure access

Graeme Lufkin gwl at u.washington.edu
Thu Nov 7 02:18:51 CET 2002

	Okay, I think I understand what's going on, and why
return_internal_reference<> does what I want.  I used it, and it works. 
But if the default behavior is to return a copy, why did the other
access/assignments work.  That is, in the python code: 
> >>> at = Atom()
> >>> print at.x
> 0.0
> >>> at.x = 42
> >>> print at.x
> 42.0
> >>> h = Holder()
> >>> print h.a.x
> 0.0
> >>> h.a.x = 43
> >>> print h.a.x
> 0.0
> >>> h.a = at
> >>> print h.a.x
> 42.0
	Why does 'at.x = 42' not also assign '42' to a temporary instance of
the 'x' member variable?  And it's not just built-in types, the
assignment of 'h.a = at' works, it doesn't assign 'at' to a temporary
'a'.  What am I missing?
	Another, unrelated question: Can operator[] be overloaded to act the
same in Python, that is like __getitem__ ?  I tried
	.def("__getitem__", &MyClass::operator[])
but it complained about sizeof() being applied to an unspecified type.
	Even more: overloading *= for a float.  My class overloads *= for
floats, and I'd like this to work in Python for integer and
floating-point python types.  So I did
	.def(self *= float())
similar to the tutorial example which uses int() instead.  Now I can do
the *= in Python, but only on integers!  For example, I can do
	foo = MyClass()
	foo *= 2
but when I try
	for *= 3.14
I get a 'TypeError: can't apply sequence to non-int' or something like
that.  Any thoughts?
	- Graeme Lufkin
	gwl at u.washington.edu
"The sleeper has awakened."

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