Paul Brannan: Avoiding Pitfalls in C Extensions

Kevin — Fri, 02 Nov 2007 14:24:00 -0600

What’s a strategy for playing werewolf? Paying attention to the details of what is going on. This is a also a good strategy for writing C extensions to ruby – maybe you’re pair programming and maybe you’re not, but if you have a bug, your code will likely crash hard; pay attention!

Don’t be afraid to write a ruby extension, but there are definitely things that you should be aware of before you start:

you will often have two objects that are representing the same thing, but one is the C object and one is the ruby object – do not give these variables the same name! Use a naming convention that differentiates them
ranges for your data types are important during conversions!
allocate resources and deallocate resources in the same place if possible!
do not destroy an object that does not belong to you!
check function return values!
make sure you use rb_ensure!
executing arbitrary code and using tainted data are potential security concerns!
unit testing is hard, as many C libraries were not built with unit testing in mind, but functional tests that execute your extension code are quite necessary!
convert C++ exceptions to ruby exceptions at C++/Ruby boundaries and vice versa!
use the Pstore database if you need a database – it’s simple!
implement to_s and inspect for any custom classes! they’re useful!
use virtual destructors when doing inheritance!
there are tools to help – Rice, etc!
damn straight!

notkeepingitreal.com: Paul Brannan: Avoiding Pitfalls in C Extensions

Paul Brannan: Avoiding Pitfalls in C Extensions