Created by: matteolegna
Hi! I have spotted what I think is a bug. I am quite of a noob; hopefully, I am doing the right thing creating this pull request...
Addressed problem description
I've noticed that the Formula Node does not work when inputting an expression that lacks any variable. For example, typing x + 3 (given the default value for x of 0), it does correctly evaluate outputting 3. Typing 3 + 1 gives no result, as the for loop https://github.com/nortikin/sverchok/blob/e9cfe0c77f07844564a9121ba5821cad96701edf/nodes/number/formula3.py#L190 never runs if var_names == false
Solution description
zip_long_repeat(*objects) returns an empty iterator if objects is ([],).
My proposed fix is aimed to make objects equal to ([None],) when there are no variables in the expression. Thus list(zip_long_repeat(*objects)) = (None,) and the for loop runs once.
Preflight checklist
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Code changes complete. -
Manual testing done. -
Ready for merge.