C++ assignment to boost::python::object doesn't work. Why? -

according documentation, assignment here should work, doesn't:

#include <boost/python.hpp> #include <iostream>  int main(int, char **) {     using namespace boost::python;     py_initialize();      object test = object(2.05); //this works fine     test = 3.05;                //compiler error      std::cout << extract<double>(test) << std::endl;      py_finalize();     return 0; } 

here's compiler output:

g++ -std=c++1y -i/usr/local/cellar/python3/3.5.0/frameworks/python.framework/versions/3.5/include/python3.5m -i/usr/local/cellar/boost/1.59.0/include -o0 -g3 -wall -c -fmessage-length=0 -mmd -mp -mf"test.d" -mt"test.d" -o "test.o" "../test.cpp" ../test.cpp:9:10: error: no viable overloaded '='     test = 3.05;     ~~~~ ^ ~~~~ /usr/local/cellar/boost/1.59.0/include/boost/python/object_core.hpp:241:9: note: candidate function (the implicit move assignment operator) not viable: no known conversion 'double' 'boost::python::api::object' 1st argument   class object : public object_base         ^ /usr/local/cellar/boost/1.59.0/include/boost/python/object_core.hpp:241:9: note: candidate function (the implicit copy assignment operator) not viable: no known conversion 'double' 'const boost::python::api::object' 1st argument   class object : public object_base         ^ 1 error generated. make: *** [test.o] error 1 

the documentation states that:

object msg = "%s bigger %s" % make_tuple(name,name); 

demonstrates can write c++ equivalent of "format" % x,y,z in python, useful since there's no easy way in std c++.

however, can't work. why isn't boost::python able auto convert double? actually, not doubles, type.

here's environment info:

• osx yosemite
• llvm 6.1.0
• python 3.5.0
• boost 1.59.0
• eclipse ide

edit: works

int main(int, char **) {     py_initialize();      //object test = object(2.05); //this works fine     //test = 3.05;                //compiler error      str name = "test";     str name = name.upper();     object msg = "%s bigger %s" % make_tuple(name,name);      std::cout<<std::string(extract<const char*>(msg))<<std::endl;      py_finalize();     return 0; } 

so it's looking cannot assign c++ types without first creating boost::python object forever suggesting.

because object constructor explicit

  template <class t>   explicit object(t const& x); 

it's forbidden use implicit conversion object = t();. can use following thing:

object test = object(2.05);