old_contents: """
  Interpolate OpenType Layout tables (GDEF / GPOS / GSUB).
  """
  from __future__ import print_function, division, absolute_import
  from fontTools.misc.py23 import *
  from fontTools.ttLib import TTFont
  from fontTools.varLib import models, VarLibError, load_designspace
  from fontTools.varLib.merger import InstancerMerger
  import os.path
  import logging
  from pprint import pformat
  
  log = logging.getLogger("fontTools.varLib.interpolate_layout")
  
  
  def interpolate_layout(designspace_filename, loc, master_finder=lambda s:s, mapped=False):
  	"""
  	Interpolate GPOS from a designspace file and location.
  
  	If master_finder is set, it should be a callable that takes master
  	filename as found in designspace file and map it to master font
  	binary as to be opened (eg. .ttf or .otf).
  
  	If mapped is False (default), then location is mapped using the
  	map element of the axes in designspace file.  If mapped is True,
  	it is assumed that location is in designspace's internal space and
  	no mapping is performed.
  	"""
  
  	axes, internal_axis_supports, base_idx, normalized_master_locs, masters, instances = load_designspace(designspace_filename)
  
  
  	log.info("Building interpolated font")
  	log.info("Loading master fonts")
  	basedir = os.path.dirname(designspace_filename)
  	master_ttfs = [master_finder(os.path.join(basedir, m['filename'])) for m in masters]
  	master_fonts = [TTFont(ttf_path) for ttf_path in master_ttfs]
  
  	#font = master_fonts[base_idx]
  	font = TTFont(master_ttfs[base_idx])
  
  	log.info("Location: %s", pformat(loc))
  	if not mapped:
  		loc = {name:axes[name].map_forward(v) for name,v in loc.items()}
  	log.info("Internal location: %s", pformat(loc))
  	loc = models.normalizeLocation(loc, internal_axis_supports)
  	log.info("Normalized location: %s", pformat(loc))
  
  	# Assume single-model for now.
  	model = models.VariationModel(normalized_master_locs)
  	assert 0 == model.mapping[base_idx]
  
  	merger = InstancerMerger(font, model, loc)
  
  	log.info("Building interpolated tables")
  	merger.mergeTables(font, master_fonts, ['GPOS'])
  	return font
  
  
  def main(args=None):
  	from fontTools import configLogger
  
  	import sys
  	if args is None:
  		args = sys.argv[1:]
  
  	designspace_filename = args[0]
  	locargs = args[1:]
  	outfile = os.path.splitext(designspace_filename)[0] + '-instance.ttf'
  
  	# TODO: allow user to configure logging via command-line options
  	configLogger(level="INFO")
  
  	finder = lambda s: s.replace('master_ufo', 'master_ttf_interpolatable').replace('.ufo', '.ttf')
  
  	loc = {}
  	for arg in locargs:
  		tag,val = arg.split('=')
  		loc[tag] = float(val)
  
  	font = interpolate_layout(designspace_filename, loc, finder)
  	log.info("Saving font %s", outfile)
  	font.save(outfile)
  
  
  if __name__ == "__main__":
  	import sys
  	if len(sys.argv) > 1:
  		sys.exit(main())
  	import doctest
  	sys.exit(doctest.testmod().failed)
  
new_contents: """
  Interpolate OpenType Layout tables (GDEF / GPOS / GSUB).
  """
  from __future__ import print_function, division, absolute_import
  from fontTools.misc.py23 import *
  from fontTools.ttLib import TTFont
  from fontTools.varLib import models, VarLibError, load_designspace
  from fontTools.varLib.merger import InstancerMerger
  import os.path
  import logging
  from pprint import pformat
  
  log = logging.getLogger("fontTools.varLib.interpolate_layout")
  
  
  def interpolate_layout(designspace_filename, loc, master_finder=lambda s:s, mapped=False):
  	"""
  	Interpolate GPOS from a designspace file and location.
  
  	If master_finder is set, it should be a callable that takes master
  	filename as found in designspace file and map it to master font
  	binary as to be opened (eg. .ttf or .otf).
  
  	If mapped is False (default), then location is mapped using the
  	map element of the axes in designspace file.  If mapped is True,
  	it is assumed that location is in designspace's internal space and
  	no mapping is performed.
  	"""
  
  	axes, internal_axis_supports, base_idx, normalized_master_locs, masters, instances = load_designspace(designspace_filename)
  
  
  	log.info("Building interpolated font")
  	log.info("Loading master fonts")
  	basedir = os.path.dirname(designspace_filename)
  	master_ttfs = [master_finder(os.path.join(basedir, m.filename)) for m in masters]
  	master_fonts = [TTFont(ttf_path) for ttf_path in master_ttfs]
  
  	#font = master_fonts[base_idx]
  	font = TTFont(master_ttfs[base_idx])
  
  	log.info("Location: %s", pformat(loc))
  	if not mapped:
  		loc = {name:axes[name].map_forward(v) for name,v in loc.items()}
  	log.info("Internal location: %s", pformat(loc))
  	loc = models.normalizeLocation(loc, internal_axis_supports)
  	log.info("Normalized location: %s", pformat(loc))
  
  	# Assume single-model for now.
  	model = models.VariationModel(normalized_master_locs)
  	assert 0 == model.mapping[base_idx]
  
  	merger = InstancerMerger(font, model, loc)
  
  	log.info("Building interpolated tables")
  	merger.mergeTables(font, master_fonts, ['GPOS'])
  	return font
  
  
  def main(args=None):
  	from fontTools import configLogger
  
  	import sys
  	if args is None:
  		args = sys.argv[1:]
  
  	designspace_filename = args[0]
  	locargs = args[1:]
  	outfile = os.path.splitext(designspace_filename)[0] + '-instance.ttf'
  
  	# TODO: allow user to configure logging via command-line options
  	configLogger(level="INFO")
  
  	finder = lambda s: s.replace('master_ufo', 'master_ttf_interpolatable').replace('.ufo', '.ttf')
  
  	loc = {}
  	for arg in locargs:
  		tag,val = arg.split('=')
  		loc[tag] = float(val)
  
  	font = interpolate_layout(designspace_filename, loc, finder)
  	log.info("Saving font %s", outfile)
  	font.save(outfile)
  
  
  if __name__ == "__main__":
  	import sys
  	if len(sys.argv) > 1:
  		sys.exit(main())
  	import doctest
  	sys.exit(doctest.testmod().failed)
  
subject: use DesignSpaceDocument instead of varLib.designspace