Embedded libraries

RoboFont comes with batteries included – that is, common functionality for building font-related tools come with the application. Several core Python libraries are embedded and ready to use in your scripts.

Developers can rely on RoboFont for keeping essential libraries up-to-date: RoboFont updates also include updates to all embedded libraries, if they are available.

In some cases, however, it may be necessary to use a different version of a library that comes with RoboFont – for example, the latest development version, an older version without a recent bug, your own private fork etc.

Overriding embedded libraries

The recommended way of overriding embedded modules in RoboFont is using the external_packages folder, which can be found inside your user’s Application Support folder. (If this folder does not yet exist, you’ll have to create it manually.)

/Users/myUsername/Library/Application Support/RoboFont/external_packages

RoboFont scans this folder during start-up and loads these packages first, so they have precedence over everything else which is loaded later.

Using the external_packages folder will install packages for RoboFont 3 only – not for the system-level Python.

Example: Using the development version of fontTools

As an example, imagine that you need to use the latest version of fontTools from GitHub instead of the one that comes embedded in RoboFont.

The first step is downloading the fontTools source code. You can do that by downloading and extracting the zip, or by using git clone:

cd my/parent/folder
git clone http://github.com/fonttools/fonttools.git

Once you have the source code in your machine, there are two ways to make the package available to RoboFont:

  1. moving or copying the whole package into the external_packages folder
  2. creating a .pth file pointing to the package’s location

Checking the current version of a library

Use Python to check which version of a library RoboFont is using:

import fontTools

This is the version which comes embedded with RoboFont:


This is the locally installed version:

Last edited on 01/09/2021