[C++-sig] Re: Calling a python function from C++

[David Abrahams]

Jeff Holle <jeff.holle at verizon.net> writes:

> Dave wrote:
>
> Why struggle?
> This should be:
>
> object    /* Returns a borrowed reference */
> getPythonFunction(string moduleName,string functionName)
> {
>     object _module(handle<>( PyImport_ImportModule(const_cast<char*>(moduleName.c_str())))); <<-- line 63 in Main.cpp
>
>     return _module.attr(functionName.c_str());
> }
>
> ------------------------------------------------------------------------
>
> Always a good question.
> The code doesn't compile as presented.

Oh, it should; GCC bug it looks like.

  object
  getPythonFunction(string moduleName,string functionName)
  {
      object _module = object(
          handle<>(
              PyImport_ImportModule(const_cast<char*>(moduleName.c_str()))
          )
      );

      return _module.attr(functionName.c_str());
  }

or 

  object
  getPythonFunction(string moduleName,string functionName)
  {
      object _module((
          handle<>(
              PyImport_ImportModule(const_cast<char*>(moduleName.c_str()))
          )
      ));

      return _module.attr(functionName.c_str());
  }

works.

> An underlining concern I have is error handling.  When
> PyImport_ImportModule fails, a NULL pointer is returned.
> Seems like the underlining machinery in "handle<>" is intolerant of
> this. 

What makes you say that?

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com