Question

Occasionally, I have come across programming techniques that involve creating application frameworks or websites in Java, PHP or Python, but when complex algorithms are needed, writing those out in C or C++ and running them as API-like function calls within your Java/PHP/Python code.

I have been googling and searching around the net for this, and unless I don’t know the name of the practice, I can’t seem to find anything on it.

To put simply, how can I:

1. Create functions or classes in C or C++
2. Compile them into a DLL/binary/some form
3. Run the functions from –
   • Java
   • PHP
   • Python
4. I suspect JSON/XML like output and input must be created between the Java/PHP/Python and the C/C++ function so the data can be easily bridged, but that is okay.

I’m just not sure how to approach this technique, but it seems like a very smart way to take advantage of the great features of Java, PHP, and Python while at the same time utilizing the very fast programming languages for large, complex tasks.

The other thought going through my head is if I am creating functions using only literals in Java/PHP/Python, will it go nearly as fast as C anyway?

The specific tasks I’m looking to work with C/C++ on is massive loops, pinging a database, and analyzing maps. No work has started yet, its all theory now.

Answer 1

You can easily extend a python script with custom C++ code using Boost.Python, see this website for more details: http://www.boost.org/doc/libs/1_50_0/libs/python/doc/

This is how you can use it:

char const* greet()
{
   return "hello, world";
}

#include <boost/python.hpp>

BOOST_PYTHON_MODULE(hello_ext)
{
    using namespace boost::python;
    def("greet", greet);
}

You need to compile this into a shared library. You will get a .dll on windows and a .so on Linux. The library will include the necessary code to make it available to python. Example using it:

>>> import hello_ext
>>> print hello_ext.greet()
hello, world

Here are some more examples: http://www.boost.org/doc/libs/1_50_0/libs/python/doc/tutorial/doc/html/index.html

When using Boost.Python remember to link your shared object to python if you are not using weak dynamic linking. There are similar things for PHP and Java.

As for other languages, I never used a custom shared library with Java but did so with PHP and it was a pain using the native Api. I found using swig way more pleasant.