sage.sets: Doctest cosmetics

[mkoeppe]

Cherry-picked from #35095.

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[mantepse]

I am against replacing short lambda expressions with two line def in docstrings: they are a pain to copy into the repl.

[github-actions]

Documentation preview for this PR (built with commit 5ef67f5; changes) is ready! 🎉
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[mkoeppe]

I am against replacing short lambda expressions with two line def in docstrings: they are a pain to copy into the repl.

Are you referring to copying from the source code or from the formatted HTML documentation? Where exactly does it hurt?

[mantepse]

I am against replacing short lambda expressions with two line def in docstrings: they are a pain to copy into the repl.

Are you referring to copying from the source code or from the formatted HTML documentation? Where exactly does it hurt?

Copying from source code. It does work, but it is a painful. For example, modifying does not work as well, and also emacs doesn't offer autocompletion for functions defined in this way.

Also, I don't see a good reason for the replacement. What is the purpose?

[mkoeppe]

What is the purpose?

Coding style. In library code, such lambda assignments are flagged by pycodestyle, and they have been replaced already. Best to use a consistent style also in code examples.

[mkoeppe]

Copying from source code.

You know that you can copy the whole lines including prompts, yes?

[mantepse]

What is the purpose?

Coding style. In library code, such lambda assignments are flagged by pycodestyle, and they have been replaced already. Best to use a consistent style also in code examples.

I would agree that in very many cases the assignment is unnecessary, and could simply be inlined.

Otherwise, you could simply use the one-line form of def:

def f(x): return 2*x 

works just fine.

Copying from source code.

You know that you can copy the whole lines including prompts, yes?

Is there an editor that would not let you copy full lines?

[mkoeppe]

We appear to be miscommunicating. What's the exact problem that you are facing when copying multi-line definitions?

[mkoeppe]

use the one-line form of def:

def f(x): return 2*x 

Codestyle linters also don't like that

[mantepse]

It is a bit hard to explain if you do not use emacs.

I can go to the first line of the test in the documentation buffer, and press C-d, to run the snippet in the attached sage session. It will look as follows:

sage: %cpaste
Pasting code; enter '--' alone on the line to stop or use Ctrl-D.
:def rotate_permutation(p):
:    cycle = Permutation(tuple(range(1, len(p)+1)))
:    return Permutation([cycle.inverse()(p(cycle(i))) for i in range(1, len(p)+1)])
:--

If I do it this way (rather than copy-pasting), I at least get tab completion. However, if I now want to modify the definition slightly, it gets a bit cumbersome, at least for me.

I also find that the increased verbosity is another drawback.

I do see the point of using pycodestyle, but I would rather turn off that particular recommendation for doctests, or relax it to allow single line def statements.

[mkoeppe]

Is this sage-shell-mode?

[mantepse]

Yes

[mkoeppe]

I've reduced this PR to the subset of the changes that do not involve changing lambda assignments to defs.

[mantepse]

LGTM, thank you!

[mkoeppe]

Thanks.