Fix DIP Parts to run with FreeCAD 0.18 and Python 3

[acisternino]

Fixes issue running the DIP Parts scripts with FreeCAD 0.18 and Python 3.

Mostly float division and import issues.

[easyw]

@acisternino
does your fix work both with py3 & py2 (i.e. FC 0.18 & FC0.17)?

[acisternino]

@easyw
I am sorry, I have tested it only with FC 0.18/Py3. I'll give it a try as soon as possible but I don't think it is compatible.

The integer division fixes probably are but the use of importlib.reload and other changes surely not.

Feel free to close this if you don't want to wait.

[easyw]

@acisternino
I can wait .. no hurry at all
If possible I would like to have it back compatible, but the need is not so important considering that the actual stable release is 0.18.4 and from now on all will be py3 only.

[Qbort]

the use of importlib.reload

The only alternative that works in python2 and python3 is imp.reload. However "imp" package is deprecated in Python3...

Shouldn't this repository move away from supporting python 2 anyway? See #315

I ask because I'm working on similar fixes for BGA packages and others that do not work with FC 0.18.

[easyw]

@Qbort

The only alternative that works in python2 and python3 is imp.reload.

a solution is already adopted here:

kicad-3d-models-in-freecad/cadquery/FCAD_script_generator/CP_Tantalum_SMD/main_generator.py

Lines 141 to 146 in e935e68

	def reload_lib(lib):
	if (sys.version_info > (3, 0)):
	import importlib
	importlib.reload(lib)
	else:
	reload (lib)

[acisternino]

Another solution could be using something like this:

try:
    reload          # Python 2.7
except NameError:
    from importlib import reload   # Python 3.4+

I'll try to find solutions for the other features.

[Qbort]

It would be good if we can agree the "best method" to do this. I am already in process of fixing all modules (see my PR #374) and what I have done is define the below function in cq_cad_tools.py

kicad-3d-models-in-freecad/cadquery/FCAD_script_generator/CP_Tantalum_SMD/main_generator.py

Lines 141 to 146 in e935e68

	def reload_lib(lib):
	if (sys.version_info > (3, 0)):
	import importlib
	importlib.reload(lib)
	else:
	reload (lib)

Then at the top of all files that use import, I added below 3 lines of code:

https://github.com/Qbort/kicad-3d-models-in-freecad/blob/python3_support/cadquery/FCAD_script_generator/4UCON_17809/main_generator.py#L109-L111

I'd rather agree this before I go too far with my changes on my PR #374 ...

[easyw]

I'd rather agree this before I go too far with my changes on PR

@Qbort this approach seems fine.. adding the code in a common module is requiring to check and fix all the generators... is what you are you going to do? If so I'm fine with this approach 😄

[easyw]

Another solution could be using something like this:

@acisternino in general I try to use [try excet] as little as possible inside the code... I would prefer to keep the first solution suggested