Strange behavior with ternary operator

[sadseeker]

I noticed strange behavior while trying to use ternary operator with boost::python::dict and list.
I'm trying to do something like this

using py = boost::python;

py::dict globals;
py::dict dict;
py::list list;
bool condition = true;
globals["mol"] = condition ? dict : list;
py::exec("print(type(mol))", globals);

What I expected: <class 'list'> or <class 'dict'>
What I got: <class 'Boost.Python.function'>

Is it expected behavior? Then can someone explain me why?
Or this is a bug?

[stefanseefeld]

I wouldn't be surprised if this behaviour is the result of expression templates at work.
Try using a temporary variable to prevent lazy evaluation of the expression on the right-hand side.
Also, to confirm: what is the result of calling the function you got ? That is, what is the output of
py::exec("print(type(mol()))", globals); ?

[sadseeker]

Thanks for answer.
I can fix this by using simple if-else or casting dict and list to py::object explicitly.
But I wonder if this is expected behavior or bug

---

py::exec("print(type(mol()))", globals); ?

Probably <class 'list'> because I saw in debugger that &object::ptr would be written to globals["mol"].
Although I can't test right now

---

PS:

py::exec("print(type(mol()))", globals); ?

output:

PythonException:
Type: ArgumentError
Value: Python argument types in
None.None()
did not match C++ signature:
None(class boost::python::api::object {lvalue})
Traceback:
 <string> : 1

[e-kwsm]

globals["mol"] = condition ? dict : list;

Here dict and list must have the same type.

Try the folowing code

  globals["foo"] = true ? false : 123;  // false is converted to (int)0
  globals["bar"] = false;
  boost::python::exec("print(foo, bar)", globals);

which prints

0 False

See https://stackoverflow.com/a/8535301.