2.3. Python Coding Guidelines¶
These coding guidelines MUST be applied to all
The source files MUST be successfully checked by running the waf command
check_guidelines before files can be merged into the master branch of the
The following rules generally apply and follow the naming schema
2.3.1. Filenames (
The following rules apply for filenames of Python scripts.
Python Script Filenames
The general file naming rules MUST be applied (see Section 2.1.1), except that dashes (
-) SHOULD not be used.
Python scripts MUST use
.pyas file extension, except for waf build scripts which use
wscriptas file name.
For example the valid file names for batch scripts are
my-script.py(not recommended, as the script is not importable)
my_script.py(recommended, the script is importable)
2.3.2. Header (
Python file header
Python source and header files MUST start with the following header:
1#!/usr/bin/env python3 2# -*- coding: utf-8 -*- 3# 4# Copyright (c) 2010 - 2021, Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V. 5# All rights reserved. 6# 7# SPDX-License-Identifier: BSD-3-Clause 8# 9# Redistribution and use in source and binary forms, with or without 10# modification, are permitted provided that the following conditions are met: 11# 12# 1. Redistributions of source code must retain the above copyright notice, this 13# list of conditions and the following disclaimer. 14# 15# 2. Redistributions in binary form must reproduce the above copyright notice, 16# this list of conditions and the following disclaimer in the documentation 17# and/or other materials provided with the distribution. 18# 19# 3. Neither the name of the copyright holder nor the names of its 20# contributors may be used to endorse or promote products derived from 21# this software without specific prior written permission. 22# 23# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 24# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 26# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE 27# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 29# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 30# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 31# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 32# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33# 34# We kindly request you to use one or more of the following phrases to refer to 35# foxBMS in your hardware, software, documentation or advertising materials: 36# 37# - "This product uses parts of foxBMS®" 38# - "This product includes parts of foxBMS®"
2.3.3. Syntax (
The following rules apply for syntax of Python scripts
Python syntax rules
Python 2 only syntax MUST NOT be used.
Python 3 only syntax MAY be used.
Code MUST work in Python 3.6 or greater.
2.3.4. Formatting (
Uniform formatting makes code easier to read to all developers.
Python formatting rules
Python source files are checked for correct formatting by
black configuration can be found in
2.3.5. Static program analysis (
Static program Analysis helps to detected code smells and errors in an early stage of development.
Python static program analysis rules
Python sources files are statically checked by
configuration can be found in
2.3.6. No platform specific code (
No platform specific code
Python scripts MUST use platform independent code where ever possible. If platform specific is required, it MUST be guarded.
Example Listing 2.38 shows how to write platform acceptable platform specific code.
1 2import os 3import platform 4 5 6def some_function(): 7 """Just a dummy function""" 8 if platform.uname().system.lower().startswith("win"): 9 print("Some Windows code") 10 else: 11 print("Feature only support on windows") 12 13 path = "some/path" # bad - works on all platforms, but no good style 14 path = "some\\path" # bad - works only on Windows 15 path = os.path.join("some", "path") # good - works on every platform 16 print(path)
wscript Specific rules (
source or might be less readable if they are split over
multiple lines (as
black would format it like this on default). Therefore
source might be written as follows, if it increases
1 2import os 3 4 5def build(bld): 6 """builds something...""" 7 # fmt: off 8 # pylint: disable=line-too-long 9 includes = [ 10 # ... 11 os.path.join("..", "..", "os", "freertos"), 12 os.path.join("..", "..", "os", "freertos", "include"), 13 os.path.join("..", "..", "os", "freertos", "portable", "ccs", "arm_cortex-r5"), 14 # ... 15 ] 16 # pylint: enable=line-too-long 17 # fmt: on
# fmt: offdisables black on formatting starting from that line and
# pylint: disable=line-too-longdisables the pylint error message starting from that line.
# fmt: onre-activates black on formatting starting from that line and
# pylint: enable=line-too-longre-activates the pylint error message starting from that line.