How To: Compile every language from Vim

Warning: This post is for users of the Vim text editor. It might not be relevant to you unless you have been using it already or want a compelling argument to start doing so.

One of the many reasons I like Vim is how easy it is to set up a workable environment for any programming language. For most popular languages, filetype recognition and syntax highlighting are already in there. What I like to do further, is to set up easy compilation and running from within Vim with the click of a button. This post will show how.

We are concerned with single source files, useful for when you are starting out in a new language, doing programming competitions or merely experimenting with language features, and want a little more control than you can get with a REPL.

Setting up C compilation

We are going to start with gcc and C compilation (a sufficiently non-trivial example), but we will look at a few others in the end. To compile a file test.c with gcc into test.out, we write

$ gcc -o test.out test.c

When editing a file in Vim, you can run a command for the native terminal by preceding it with :!. For example, in Unix, try writing

:!ls

So, if we know that our filename is test.c, we can now compile and run without resorting to an external terminal window

:!gcc -o test.out test.c && ./test.out

Note we were assuming that the current directory is the directory of the file we are editing, which is not always the case. This will not be a problem as we generalize.

Now, this is already quite convenient, but what if we had longer filenames? Turns out, there is a shortcut for getting the filename, it's "%". Back to Vim:

:!gcc -o ?? "%" && ??

"%" will expand into "test.c", but how can we get test.out? We need Vim's filename modifiers. :p gives us the full path and :r removes the extension. So what we need is

:!gcc -o "%:p:r.out" "%:p" && "%:p:r.out"

This would work for every file, all that's left now is to put it in .vimrc. I like to map it to F9 like so:

autocmd FileType c map :!gcc --o "%:p:r.out" "%:p" && "%:p:r.out"

And we're good to go! Restart Vim and hit F9 while editing a C file to see it happen.

Other languages

Java classes present us with new kinds of issues, but they still fall to Vim's file modifiers. We use :h to get the classpath and :t helps us get the class name by stripping the path away.

autocmd FileType java map :!javac "%:p" && java -cp "%:p:h" "%:t:r"

Interpreted languages are even easier, here's ruby:

autocmd FileType ruby map :!ruby "%:p"

Further tips

If you want to separate compilation and execution, that's easy too. I've also added a "| more" to make sure the first error does not leave the screen.

autocmd FileType c map :!gcc --o "%:p:r.out" "%:p" more autocmd FileType c map :!"%:p:r.out"

Documentation

Although :p, :r, :h and :t should be sufficient for most cases, there is much more you can do with file modifiers. Hit up

:!help filename-modifiers

To find out more.