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FEM coding_conventions

src/Mod/Fem/coding_conventions.md

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FEM coding_conventions

These coding rules apply to FEM module code only. Other modules or the base system may use different coding rules especially in naming policy of Python.

Spelling

  • Be mindful of spelling. Spell checks are quite often neglected.

  • Utilize codespell to discover and quickly correct spelling errors.

    bash
    # Find typos
codespell -q 2 -S *.ts -S *.dyn -S *.svg -L childs,dof,dum,freez,methode,nd,normaly,programm,som,uint,vertexes,inout  src/Mod/Fem/

# Interactively fix said typos
codespell -i 3 -w -S *.ts -S *.dyn -S *.svg -L childs,dof,dum,freez,methode,nd,normaly,programm,som,uint,vertexes,inout  src/Mod/Fem/

    Notes:

    1. We recommend running the dev version as it uses the most up to date typo dictionaries.
    2. To find the most amount of typos we recommend running a quick pip install --upgrade See the codespell docs for more info.

Python and C++

Code formatting

  • All files should have a license header
  • Unix line endings will be used:
    • a .gitattributes file has been added to ensure line endings of text files are LF
    • use ?w=1 in link address to suppress line ending changes on github
  • never use mixed line endings on one file
  • 4 Spaces for indent (in this file too ;-))
  • no trailing white spaces

Python

Code formatting

  • except W503 all Python code is pep8 compliant
  • maximal line length is 100
  • double quotes as string identifier

Exceptione

Imports

  • Only one import per line.
    • on import from 'some_package' import 'some_module'. There should only be one 'some_module' per line.
    • on import from 'some_module' import 'some_method'. There should only be one 'some_method' per line.
  • Each import group should be sorted alphabetically.
  • First the 'import some_module' ones, afterwards the 'from some_module import something'.
  • First absolute path imports than relative path imports.
  • On relative path imports first the one dot ones, afterwards the two dot ones.
  • Star import should not be used at all (from some_module import *).
  • Python imports should be grouped into groups:
    • Standard library imports
    • One empty line
    • Third-party imports
    • One empty line
    • non Gui FreeCAD specific imports
      • from module FreeCAD
      • One empty line
      • other modules, but not FEM
      • One empty line
      • FEM specific imports
        • absolute imports
        • One empty line
        • relative imports
      • One empty line
    • FreeCAD Gui imports:
      • The import of Gui modules should be guarded by a 'if FreeCAD.GuiUp:'
      • On Gui only modules the guard is not needed
      • Same as above but without a empty line
      • Standard library imports
      • Third-party Gui imports
      • FreeCAD-specific imports from module FreeCADGui
      • other FreeCAD Gui imports
      • FEM Gui imports
  • The above paragraphs highly reduces merge conflicts.

Naming policy

  • snake_case_names
  • ClassNames, variable_names_without_capitals and CONSTANTS_USE_CAPITALS, functions_without_capitals
  • Function expected to return a value should indicate what is expected, so is_mesh_valid is a good name, but check_mesh is not a good name
  • Class names, method names and variable that are locally and not supposed to be used for scripting should start with underscore like _MyInternalClass

Python code formatting tools

  • flake8 in source code directory on Linux shell
bash
find src/Mod/Fem/ -name "*\.py" | xargs -I [] flake8 --ignore=E266,W503 --max-line-length=100 []
  • LGTM
  • TODO: check pylint
  • Automatic code formatter will not be used for existent code
  • For new code if someone would like to use a code formatter black should be used

Coding

  • print() vs. FreeCAD.Console.PrintMessage()
    • FreeCAD.Console.PrintMessage() or Log or Error should be used
    • print() should be used for debugging only
    • forum topic
    • BTW: Console prints need a new line where as print does not need one
  • type checking:
    • do not use hasattr(obj, "Proxy") and obj.Proxy.Type
    • use method is_of_typ(obj, "TypeString") from module femtool.femutils
  • ActiveDocument
    • try to avoid the use of App.ActiveDocument or FreeCAD.ActiveDocument
    • instead try to use some_obj.Document instead
    • try to avoid the use of Gui.ActiveDocument or FreeCADGui.ActiveDocument
    • instead try to use some_obj.ViewObject.Document or some_view_obj.Document
    • activeDocument() is more robust than ActiveDocument
    • forum topic
    • FreeCAD Python console
      • in code examples which will be copied in FreeCAD Python console
      • it is common to use App.ActiveDocument.some_obj or method

Documenting

Python style is preferred over Doxygen style - see ccx tools module in fem tools package - see forum topic

Module structure

  • task panels should go into a separate package too
    • according pep8 imports should be on module beginning
    • if task panel class in inside viewprovider module, the imports needed for task panel are module beginning too
    • might be some special plot module or what ever is needed
    • if this is not available the object can not even created
    • if task panel is separate the object can be createdh

C++

Naming policy

  • CamelCase names

Code formatting

  • slashes
    • Do not use to many slashes in a row. This could cause trouble with Doxygen.
    • see PR with comment

Icons

Naming plicy