Rebuild the named instances in a designspace 5 file based on the axis labels. Use with caution!

make_named_instances_from_axis_labels.py

import argparse
from itertools import product
import sys
from fontTools.designspaceLib import DesignSpaceDocument


def main():
    parser = argparse.ArgumentParser(
        description="Makes new named instances based on the axis labels"
    )
    parser.add_argument("input", help="The source .designspace file")
    parser.add_argument("output", help="The destination .designspace file")
    args = parser.parse_args()

    doc = DesignSpaceDocument.fromfile(args.input)
    defaultSource = doc.findDefault()
    familyName = defaultSource.familyName
    doc.instances = []

    allLabels = [[(axis.name, label) for label in axis.axisLabels] for axis in doc.axes]
    for labels in product(*allLabels):
        styleName = " ".join(label.name for _, label in labels if not label.elidable)
        if not styleName:
            styleName = doc.elidedFallbackName
        location = {axisName: label.userValue for axisName, label in labels}
        doc.addInstanceDescriptor(
            familyName=familyName, styleName=styleName, userLocation=location
        )

    doc.write(args.output)


if __name__ == "__main__":
    main()