Filters (shallow-)copy glyph set by default

[madig]

The filter seems to not draw a dottedCircle into a UFO, unless you pass in the glyphset/layer expliticly:

from ufoLib2 import Font
from ufo2ft.filters.dottedCircleFilter import DottedCircleFilter
ufo = Font()
ufo.info.xHeight = 500
philter = DottedCircleFilter()
philter(ufo)
assert "dottedCircle" in ufo or "uni25CC" in ufo

Fails on the assert. It passes if you call philter(ufo, ufo.layers.defaultLayer).

Is this intended behavior?

[anthrotype]

definitely not intended behaviour. is this only happening with DottedCircleFilter or with any other filter?

[madig]

As Cosimo found:

ufo2ft/Lib/ufo2ft/util.py

Line 61 in 5a5f6df

self = cls((g.name, g) for g in layer)

This shallow copy is fine if you mod existing glyphs, but here we add a glyph, landing it in nirvana. @anthrotype says we should maybe change all instances of glyphSet = _GlyphSet.from_layer(font) to glyphSet = font.layers.defaultLayer in filters. The problem doesn't typically come up because ufo2ft's preprocessor code makes and uses its own glyphsets and passes them in explicitly, whereas here we implicitly want the current UFO to be modified.