less.css sharing variables across files

The best way to do this is to @import your LESS file with all your variables in it. Here's the syntax for the @import keyword:

// For LESS file includes,
@import "lib.less";
// or
@import "lib"; // infers the .less extension

// and for plain CSS includes which are added but not parsed by LESS
@import "style.css";

This works especially well if you serve CSS files to your users (as opposed to the in-browser less.js parsing) because the @import statement will compound your LESS and CSS files into one single CSS file. Maybe you can consider having one controller LESS file that includes your variables, then your other LESS and CSS files so that the end result is one single file you serve to the browser.

I imagine it would be something simple like this:

// Controller.less
@import "english.less";
@import "chart.less";