Do less

[simoncozens]

This skips over steps which are not necessary for font conversion when generating UFO files. See #673

[anthrotype]

LGTM

can you fix the lint failure before merge?

Also can you tell us what the speed savings are for an average font?

[anthrotype]

maybe list exactly what is dropped

[simoncozens]

import glyphsLib
from timeit import timeit

def convert_minimal():
    glyphsLib.load_to_ufos("SofiaSans-VF-New.glyphs", minimal=True)

def convert_maximal():
    glyphsLib.load_to_ufos("SofiaSans-VF-New.glyphs", minimal=False)

minimal = timeit(convert_minimal, number=15)
maximal = timeit(convert_maximal, number=15)
print("minimal=True: %f" % minimal)
print("minimal=False: %f" % maximal)

minimal=True: 68.512878
minimal=False: 44.625200

Yes, that's right. Avoiding running unnecessary code takes 54% longer. I don't understand it either.

[simoncozens]

Looks like it's caching/data locality issues with the parser. Here's another test:

import glyphsLib
from timeit import timeit

parsed = glyphsLib.GSFont("SofiaSans-VF-New.glyphs")

def convert_minimal():
    glyphsLib.to_ufos(parsed, minimal=True)

def convert_maximal():
    glyphsLib.to_ufos(parsed, minimal=False)

maximal = timeit(convert_maximal, number=10)
minimal = timeit(convert_minimal, number=10)
print("minimal=True: %f" % minimal)
print("minimal=False: %f" % maximal)

# Try other order, just to make sure.
minimal = timeit(convert_minimal, number=10)
maximal = timeit(convert_maximal, number=10)
print("minimal=True: %f" % minimal)
print("minimal=False: %f" % maximal)

minimal=True: 21.209306
minimal=False: 22.644560
minimal=True: 20.398469
minimal=False: 21.063948

So what - 5% faster generating UFOs?

[simoncozens]

I'd like to get this merged, but it's kind of a breaking change.

For the majority use case (building fonts), it makes things faster and it also avoids certain stupid bugs: I have a build failing because there's a background glyph with a non-existent component - which shouldn't make any difference to the build process, but means that complete UFOs can't be generated, which stops everything dead.

But for the glyphs<->UFO<->glyphs workflow, changing the default to be "minimal=True" might muck things up. So I would like to check with @belluzj and @madig before merging.

(An obvious alternative is that we set default to "minimal=False" and turn on "minimal=True" in build systems. Yeah, that's clearly better...)

[anthrotype]

turn on "minimal=True" in build systems

I believe that's preferable

[anthrotype]

LGTM thanks