DIY: Binding Lua5.3 with C++11

Let's bind C++ stuff to Lua5.3! :)

THE MEAT AND POTATOES

It might be enough to simple scripting for several projects.

BRUTEFORCE WAY

Our main weapon is C++, so the above code doesn't satisfies me. So, let's bind C++ classes and create instances from Lua.

It works fantastic. Then MyClass is able to be generated with scripting, and the garbage collector calls our destructor and delete it.
However, it might be unpleasant chore to make additional method and classes. The bind code is too long and messy!

HACKING

Let's make stuff fun. The most brilliant thing for us is we are living in future. Now, C++11 allow us what we couldn't do before.

Below code is all to bind MyClass:


Most simple binds are able to be written with lambda. So, for compile it C++11 must be enabled. To prevent crashes by scripting bug, define a GET_MYCLASS macro to ensure the first element of the Lua stack is our MyClass. Note that MyClass instances are constructed with placement new. In this case, the destructor must be called directly instead of calling delete operator.

BindClass defined like below:


As you can see, there is no MyClass dependencies. To avoid dependencies, I made a closer generator and put the class names and userdata creators into upvalue. Of course, BindClass can also be used for binding two or more extra classes.

CONCLUSION

Binding to Lua is not so complex and easy to learn. It's only combinations of small number of features such as stack and metatables. I saw programmers bothered increasing binding codes. I bet we can simplify them. Hope this helps to find your own solution.