Handle footprint name as string

[akosmarton]

If the footprint name contains only numeric characters, it should be converted to string to ensure the proper rules checking.

[cpresser]

This looks simple enough.
But I have no clue why this change is needed. Can you elaborate on that?
Do you have an example footprint where this patch changes the outcome of the check script?

[cpresser]

also convert to str here.

[cpresser]

same as above.

[akosmarton]

For example Molex uses numeric-only part numbers.

You can see the error message below if the module name contains only numeric characters:

./check_kicad_mod.py ~/work/sharkrf-kicad-library/footprints/srf_Molex.pretty/5051100892.kicad_mod

Traceback (most recent call last):
  File "./check_kicad_mod.py", line 117, in <module>
    rule.check()
  File "/home/makos/work/kicad-library-utils/pcb/rules/F7_4.py", line 140, in check
    return any([self.checkPads(module.pads)])
  File "/home/makos/work/kicad-library-utils/pcb/rules/F7_4.py", line 46, in checkPads
    exposed_pad_search = re.search('\-\d+[EP]{2}', fpName, re.IGNORECASE)
  File "/usr/lib64/python3.8/re.py", line 201, in search
    return _compile(pattern, flags).search(string)
TypeError: expected string or bytes-like object

[evanshultz]

That is not a valid footprint name for this library. See our footprint naming scheme at https://kicad-pcb.org/libraries/klc/F3.6/. And these check scripts are for those guidelines/rules. So as @cpresser said, this doesn't hurt anything but it's not needed when building footprints that conform to the rules of this library.

[cpresser]

I think this is a use full addition anyway. The scripts should not throw a cryptic error message just because the user put in stupid input.

The next logical step is to create a F3.py that actually checks that rule. I just skimmed over the F3 section of KLC, and it seems there is no way a footprint can only contain numbers. So we could check that.
And perhaps throw a warning if its number of characters is <3.
And throw errors if it contains evil code-points (thinking of emojis, german umlauts, ...)

[chschlue]

german umlauts

Those are still considered evil?
SCNR

[chschlue]

Bad jokes aside, we might have to (and be able to) relax naming rules. See KiCad/kicad-symbols#2938

[cpresser]

Nevertheless, we can have a script output a warning if non latin chars are used.
A good check would verify that any char is present in the kicad font. Basically an explicit whitelist.

Somewhat off-topic
Footprint-names are also file-names. Yay!
I have no clue how the Pi would do as filename for windows/linux/mac users. With different locales even more complication could arise.

[chschlue]

Yes, I'm not opposed to this PR.

OT: True, the π example is a symbol. But all supported platforms can handle multibyte filenames and assuming there have already been users calling their schematics MyCool80'sHeävÿMëtälPCB.sch or something without issue, I guess KiCad's codebase isn't too brittle.

Even more OT: I wonder how many ERP systems these π parts broke along the supply chain ;)

Edit: Not to mention Cyrillic/Greek/Arabic/whatever users in general.