How to set a including path in the Gjs code?

Question

As i could see, the Gjs imports, loads only /usr/share/gjs-1.0 and /usr/lib/gjs-1.0 by default. I want to modularize an application, like we can do with node, but i must find modules relative to the script file.

I found this two ways to add include paths:

1. gjs --include-path=my-modules my-script.js
2. GJS_PATH=my-modules gjs my-script.js

...but both are related to the current directory, not to the file (obliviously), and they needed to be declared on the command line, making this unnecessarily complex.

How can i set a including path in the Gjs code? (So i can make this relative to the file)

Or... There is another way to import files from anywhere, like in python?

(Please, you don't need to propose to use a shellscript launcher to solve the --include-path and GJS_PATH problem. That is obvious, but less powerful. If we do not have a better solution, we survive with that.)

Answer 1

As Douglas says, you do need to modify imports.searchPath to include your library location. Using . is simple, but depends on the files always being run from the same directory location. Unfortunately finding the directory of the currently executing script is a huge hack. Here's how Gnome Shell does it for the extensions API

I've adapted this into the following function for general use:

const Gio = imports.gi.Gio;

function getCurrentFile() {
    let stack = (new Error()).stack;

    // Assuming we're importing this directly from an extension (and we shouldn't
    // ever not be), its UUID should be directly in the path here.
    let stackLine = stack.split('\n')[1];
    if (!stackLine)
        throw new Error('Could not find current file');

    // The stack line is like:
    //   init([object Object])@/home/user/data/gnome-shell/extensions/[email protected]/prefs.js:8
    //
    // In the case that we're importing from
    // module scope, the first field is blank:
    //   @/home/user/data/gnome-shell/extensions/[email protected]/prefs.js:8
    let match = new RegExp('@(.+):\\d+').exec(stackLine);
    if (!match)
        throw new Error('Could not find current file');

    let path = match[1];
    let file = Gio.File.new_for_path(path);
    return [file.get_path(), file.get_parent().get_path(), file.get_basename()];
}

Here's how you might use it from your entry point file app.js, after defining the getCurrentFile function:

let file_info = getCurrentFile();

// define library location relative to entry point file
const LIB_PATH = file_info[1] + '/lib';
// then add it to the imports search path
imports.searchPath.unshift(LIB_PATH);

Wee! now importing our libraries is super-easy:

// import your app libraries (if they were in lib/app_name)
const Core = imports.app_name.core;

Answer 2

You need to set or modify imports.searchPath (which is not obvious because it doesn't show up with for (x in imports)print(x)). So this:

imports.searchPath.unshift('.');
var foo = imports.foo;

imports the file “foo.js” as the foo object.

This is compatible with Seed, although there imports knows it has a searchPath.

(Earlier versions of this answer were substantially less accurate and more inflammatory. Sorry).