SCons and vim

I recently played around with SCons, a build system alternative to GNU/Make. It is quite handy and relieves programmers from a lot of work. Building a program from two C files is as easy as putting

Program(['foo.c', 'bar.c'])

into a SConstruct file and running scons which will compile object files from foo.c and bar.c and link them to program foo. Cleaning up everything is easy, too. scons -c will do the trick. Apart from being easy for daily use, SCons is quite powerful. SConstruct files are Python scripts and so you get the whole power of a programming language for creating your builds.

As I revealed in an earlier post, I like the vim editor very much. When I started editing SConstruct files, I also wanted to use vim's beautiful syntax highlighting abilities with it. In command mode, you can type set filetype=python and syntax coloring works. But in real life, you don't want to type this every time you edit a file, so it would be nice, if vim detects the file type for you. It does this automatically for .c, .cpp, .sh and many more file types, but up to now it does not know about SConstruct and SConscript.

However, extending vim to recognize these is very easy using vim's autocmd features. These
let you specify actions that will be taken upon certain events, for instance when a new buffer is opened. I added two lines to my .vimrc in order to get SCons files highlighted as Python code:

autocmd BufReadPre SConstruct set filetype=python
autocmd BufReadPre SConscript set filetype=python

The syntax for autocmds is easy: After the autocmd keyword you specify the event for which you want to register this command. In our case it is before a new buffer (=file) is read. Thereafter you specify a pattern for which this applies. In our case SConstruct and SConscript files are handled, it is also possible to use regexes here. In the last part we specify the command that is executed upon the event. Here we set the file type to be Python and voila, syntax coloring works.