Incompatibility of group type reported as problem

[frankrolf]

My colleague @misbatabassum found an issue regarding the Problems report in DesignspaceEdit.

• when a designspace file is opened without the default source being open in RF, no problems are reported
• when a designspace file is opened and the default source is also open in RF, all kerning groups report mismatches, like this:

While the glyphs in the respective groups are actually the same, it is the data type of the group representation which differs (tuple vs list).

I attached an example project to reproduce this behavior:

Scenario 1:

• open Robofont
• open .designspace file via drag-drop on Robofont
• navigate to Problems tab → no Problems.

Scenario 2:

• open Robofont
• open ss_0.ufo
• open .designspace file via Extensions → DesignspaceEdit → Open …
• navigate to Problems tab → all kerning groups mismatch

designspace_edit_group_members.zip

Digging around in the code, I found that this could be circumvented by changing this line from

if sourceGroupMembers != defaultGroupMembers:

to

if list(sourceGroupMembers) != list(defaultGroupMembers):

— but that really just is a band-aid solution.

Probably something is going on here. It seems a different kind of font object is returned via AllFonts as there is via _instantiateFont. Ideally, those should be the same.

This behavior has been reproduced in Robofont 4.3 (public), as well as Robfont Version 4.4b (build 2304041121).

[frankrolf]

I dug some more, and indeed the compared object is different: one of the UFOs is open in RF, the other is submitted as a path to _instantiateFont:

from ufoProcessor import DesignSpaceProcessor
open_font = CurrentFont()
dp = DesignSpaceProcessor()
instantiated_font = dp._instantiateFont('ss_2.ufo')

print(type(open_font))
print(type(instantiated_font))

<class 'lib.fontObjects.fontPartsWrappers.RFont'>
<class 'defcon.objects.font.Font'>