On Wednesday, 5 April 2017 at 09:31:09 UTC, harfel wrote:
Dear all,
Relatively new to D in general and PyD in particular, I am
trying to wrap some D classes I wrote for use in Python.
Following the documentation and code examples, I got the basic
functionality working. However, I am struggling with
implementing the magic functions __str__ and __hash__ of the
extension class. My current approach was to implement them as
ordinary member functions:
extern(C) void PydMain() {
module_init();
// Reaction
wrap_class!(PyReaction,
PyName!"Reaction",
Init!(MultiSet, MultiSet),
Property!(PyReaction.reactants),
Property!(PyReaction.products),
Repr!(PyReaction.repr),
Def!(PyReaction.py_str, PyName!"__str__"), // XXX needs slot
Def!(PyReaction.py_hash, PyName!"__hash__"), // XXX needs slot
)();
}
but this does not work. In Python:
Python 2.7.12+ (default, Sep 17 2016, 12:08:02)
[GCC 6.2.0 20160914] on linux2
Type "help", "copyright", "credits" or "license" for more
information.
from teest_module import *
r=Reaction({'a':1, 'b':1}, {'ab':1})
r.__hash__
<built-in method __hash__ of stochcalc.Reaction object at
0x7fc1c7f4a080>
r.__hash__()
1430289695L
hash(r)
8779391257096
According to related post for C++/SWIG
(http://stackoverflow.com/questions/25199233/str-not-called-when-printing-c-class-wrapped-for-python-with-swig), the reason is that these magic methods need to be implemented as slots, rather than ordinary member functions.
Is there a way to declare these slots in PyD? I noticed that
Repr does this for __repr__ and the operator overloads do this
of course for their respective slots, but I could not find
anything for __hash__ and __str__.
Any ideas?
Thanks!
I haven't chased the source but most likely __hash__ and __str__
will be "magically" generated from toHash() and toString()
respectively (both methods of Object,
see:https://dlang.org/phobos/object.html#.Object).
