Monday, July 26, 2010

2010-07-26. Scripting with V8

Map scripting

After a long break in writing here I'm back again, and the project has taken some nice steps forward. We have been researching useful scripting languages for map scripting. This process isn't what I'm most interested in, nor does it produce cool images, so I haven't been too motivated to write about it before. I will now, shortly.

To implement complex behaviour in maps we need to use some scripting language. Common scripting languages include Javascript, Lua and Python, among others. These all have been good candidates for us.

At first I took a look at embedding Python into a C++ program. Python's micromanagement of resources, like manually incrementing and decrementing reference counters, looked shuddering. It's also a rather slow language, typical efficiency (compared to C) being around 1/200th.

I had also heard horror stories about people needing ridiculous optimizations in their Lua scripts to get even decent speed. On the other hand, Google's Chrome is one of the fastest web browsers out there when it comes to Javascript. And Google's Javascript engine, V8, is out there for free. And it natively supports C++ too. Javascript by itself isn't a dirty language either. Sounds like a dream, no?

I took some time to experiment with it. I wrote wrappers to understand it better, experimented with it, made test APIs and tools and other small libraries for it. It worked somewhat, but I ended up rewriting stuff too many times, trying to find a clean general solution for my needs.

There wasn't too much documentation for the new V8 library yet so I ended up having lots of trouble and frustration with it. I had gotten it to work, even in a way that would be useful for a small project, but I couldn't get it clean enough to use in a large game, without the frustration of having to cope with dirty code.

On top of that, when trying to compile Sad Umbrella for Arch Linux, it then appeared that the V8 release didn't even compile; it had constructs in the source code that weren't supported by the newest GCC version. Maybe they have fixed it by now, maybe not, but that wasn't the only Linux distribution having problems with V8. Many other people reported difficulties getting V8 from their Linux distribution's repositories, and it would be almost impossible to get V8 for a handheld device. If we ever decided to port the game for one.

I feel the library is still too immature for actual use by 3rd parties.

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