Chapter 9. Inline Extensions

Although Perl is a very powerful language, there are still some things that it cannot do by itself: it can't communicate directly with hardware or take advantage of complex mathematical libraries. Other things it can do, but not very quickly: you can ask Perl to rotate an image by reading in and parsing the image file format, doing all the transformations on a really big array, and writing it out again, but that takes a lot of time and effort. It's far better to ask a C library to do this for you, and the way to do this is to write an extension to allow Perl to talk to the C library. In fact, many graphical interfaces to Perl are merely extensions talking to the relevant C libraries.

The usual way to write an extension to bridge Perl and C is to use a complex and awkward intermediary language called XS (extension subroutines). If you want to do things the complex and awkward way, I suggest reading perlxstut in the Perl documentation, or my Extending and Embedding Perl (Manning). However, since one of the cardinal virtues of a Perl programmer is laziness, there has to be a less complex and awkward way to do it, right?

Thankfully, there is; Brian Ingerson got fed up with writing XS and ended up writing a very clever Perl module called Inline to do it for him. As we'll see later in the chapter, Inline has become generalized to handle languages other than C, so the module we'll look at for now is called Inline::C.