Re: [C++-sig] dict.has_key works in a Python script, not in C++

[Stefan Seefeld]

On 03/03/2010 02:10 PM, Guillaume Seguin wrote:
I have a C++ object (named hello) exposed in a Python extension using 
boost::python version 1.42. This code works :

import my_ext

aaa = my_ext.hello('aaa')

d = { aaa:12345 }

assert aaa in d #This assertion is true, as expected
assert d.has_key(aaa) #This assertion is true, as expected

But if I do the same thing on the C++ side, using 
boost::python::dict::has_key, the is key is never found.

#This Python code
assert my_ext.find_key(d, aaa)

//Calls this C++ code
bool find_key(boost::python::dict d, const hello& key_to_find)
{
    return d.has_key(key_to_find);
}

I defined the operator == like this, but it is never called.

bool hello::operator == (const hello &h) const {
    return country == h.country;
}

And my boost class is exposed like this :

using namespace boost::python;
class_<hello>("hello", init<std::string>())
    .def(self == self)
    ;

I tried stepping through the code with gdb, but I got lost ... What am 
I missing ?  TIA

Python requires dictionary keys to be immutable. I wouldn't be surprised 
if it used object identity checks (such as address comparison) instead 
of a deep equal test, as a faster way to look up objects.

    Stefan


--

      ...ich hab' noch einen Koffer in Berlin...

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