[Python-ideas] Custom Code Folding: Standardized Rules and Syntax?

Steven D'Aprano steve at pearwood.info
Sun Jul 16 11:15:59 EDT 2017

Hi Connor, and welcome!

On Sun, Jul 16, 2017 at 10:37:26AM -0400, Connor Farrell wrote:
> Background: I work in scientific computing and use Community Pycharm IDE.
> I'm a religious follower of the 'readability counts' mantra, and two things
> I find myself doing often are:
> - Writing custom code folds to segregate code, from groups of classes in a
> file, to groups of lines in an individual function. While spacing works
> great to separate ideas, my IDE allows me to collapse the entirety of the
> code in exchange for a line of English. For my purposes, this enhances
> readability immensely, as first time users are confronted with an
> explanation of the contents, rather than the code itself with a comment on
> top. I find comments don't draw the eye, and also don't have the ability to
> their code as well.

I'm afraid I'm having a lot of difficulty understanding this. I think 
the last sentence is missing a word. Comments don't have the ability to 
**what** their (whose?) code?

Which IDE are you using? When you say it collapses the "entirety of the 
code", do you mean the entire file?

> - Writing high level code, such as __init__ calls for large aggregates,
> with one keyworded argument per line (plus dict unpackings at the end),
> sort of like a simple XML file.

Even if I accept that this is a reasonable design for __init__, I would 
not agree that it is a reasonable design for "high level code" in 

> This allows me to make parameters explicit
> for other users, and optionally provide a comment indicating physical
> units, cite sources, and/or give a list of tag/enum options for every
> parameter. In the end I have 30+ line inits, but the readability is 10x
> greater.

Perhaps I might be convinced if I saw some actual code, but from your 
description alone, it doesn't sound particularly more readable. Why 
would I want to read citations in the parameter list of a method? I want 
to call the method, not do peer review on the theory behind it.

> My IDE doesn't yet offer to fold long parameter lists by default,
> but I think it makes sense.


Personally, I don't find code folding a big help. Perhaps once in a blue 
moon. I'm glad you like it and that it helps you.

> In the end, I end up with very well folded code (except for large parameter
> lists) and a bunch of co-workers asking about all the "editor-fold"
> comments that don't work in their API.

I'm afraid I'm not understanding you here either. What's an 
"editor-fold" comment? What do they mean by API? API for which 
application? How does the programming interface to an application relate 
to code folding in a text editor?

> Python was a trail-blazer in terms of emphasizing the importance of code
> readability and effective syntax. I think that we should consider some sort
> of standard for folding comments, if not only to promote stronger code
> organizations. I know standards don't usually interact with IDEs, but hey,
> the 'typing' module is pretty dang nice.
> TL;DR: Code folding is great, custom code folding is great, let's upgrade
> it to a language feature.

What does that even mean? Are you suggesting that the Python interpreter 
should raise a SyntaxError or something if your code was written in an 
editor that didn't support code folding? How would it know?

Python is a programming language. The source code is text. I should be 
able to write Python code in NotePad if I want. Why should the Python 
core devs try to force every text editor and IDE fold code exactly the 
same way? That sounds awful to me. People choose different editors 
because they like different features, and that may include the 
particular way the editor folds code. Or to not fold it at all.

I'm sorry to be so negative, but I don't understand your proposal, and 
the bits that I *think* I understand sound pretty awful to me. Perhaps 
you can explain a bit better what you mean and why it should be a 
language feature, apart from "I want everyone to lay out their source 
code the way I do". Because that's what it sounds like to me.


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