Flake8#
This is a command line lint tool that verifies that your style meets standards. Many people, including myself, detest the pedantic verification of spaces and line lengths. However, the tool will help assure that your code looks correct. Once you get comfortable writing code to the standards, it’ll go quickly and naturally. And, your code will be nicely readable!
Important!
Do not install flake8 using the Packages functionality/tab in Replit. In order to have the proper versioning, we need to
install flake8 version 5.0.4 (whereas the default version is 6.0.0). If the flake8 is not installed already, you can
install the correct version by going to the shell tab and typing in: poetry add 'flake8 5.0.4'. Don’t forget the quotes.
Turned off in tox.ini
Codes |
Descriptions |
|---|---|
W291 |
Trailing whitespace: a line has a space at the end. Although this does assure that a coding file is super clean and professional, it is way more annoying than useful. This error is ignored |
W292 |
This warning code indicates that there are no newline (blank) lines at the end of the file. This can appear to be contradictory to W391, which is also turned off. |
W391 |
This warning code indicates a blank line at the end of a file. If your file has 10s of blank lines at the end, you’ll get dinged. One blank line? Let’s ignore it. |
W504 |
This warning code indicates a line break after a binary operator. It reminds you that there should not be a line break between a binary operator (e.g., +, -, *, /) and its second operand. I figure, if it compiles and looks fine, go for it! |
E121 |
This error code indicates an indentation error. It is raised when there are inconsistencies in the indentation of code blocks, such as mismatched or inconsistent indentation levels. |
E402 |
This error code indicates a module-level import not at the top of the file. It reminds you that all imports should be placed at the beginning of the file before any other statements or code. |
tox.ini#
Important!
Do NOT modify tox.ini yourself. Mr. Stride’s unit tests will not accept any changes you make to this file.
If you fail flake8, then you’ll be penalized.
E501 line too long#
The spirit of the rule is fabulous: your code needs to be readable and lines that are too long detract from readability.
Furthermore, replit has a nifty, built-in funtion to help correct these errors: simply type ctrl+s.
(Sometimes ctrl+s doesn’t work.)
However, the default 80-character line length (although not completely arbitrary) is too short for modern development
and it doesn’t allow for other good conventions such as:
descriptive identifier names that are longer
concise, inline development style
perserving vertical real estate
We will be customizing the maximum line length to be 110 and this length will be strictly enforced. This is done by adding the
the following configuration to tox.ini:
max-line-length = 110
Why 80?
There are two good reasons why 80 was the chosen default length.
When you print code out onto paper, the typical horizontal length of a sheet of paper would allow for 80 characters to be printed. Back in the old days, computer programmers would print code out onto paper for review.
Monitors were lower resolution and typically would not allow more than 80 characters to be displayed horizontally across the screen.
Old Days of Printing
Back in the old days, many printers were called dot matrix printers where each character was comprised of an 6x7 matrix of visible dots. The paper was continuous stationary : each page was linked to the prior page via perforation and had holes on the sides to allow the printer to feed the paper through.
Egregiously long lines need to be fixed!