Add copy button to code examples

[churnikov]

Hi!

I'm planning to move this work to this repo.

@AA-Turner Suggested to me in this PR python/cpython#107037 (comment) to do that. Please tell me, what do you think :)
Do you agree that that's a good idea?

If so, I guess I would need to rewrite this function, right?
https://github.com/python/python-docs-theme/blob/main/python_docs_theme/static/copybutton.js

[AA-Turner]

We'd probably want to evaluate what exists in the literature thus far; it might be that the copybutton.js that I rewrote is redundant. It functions to hide certain Pygments classes denoting output from interactive console display blocks.

Should we decide to add a "click to copy" button, I think the functionality should be merged with the existing button.

A

[churnikov]

May I ask you, what do you mean by "We'd probably want to evaluate what exists in the literature thus far;"? :)

[AA-Turner]

E.g. https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Interact_with_the_clipboard; https://clipboardjs.com/ -- there are many ways to and libraries for interacting with the clipboard -- ought we abandon our JavaScript, ought we adopt a pre-existing library, ought we use the browser APIs, etc.

A

[ferdnyc]

FYI, there's also a pre-made sphinx_copybutton extension available, that uses clipboard.js.

(Which, btw, can):

1. Automatically remove prompts from the copied lines:

   copybutton_prompt_text = r">>> |\.\.\. "
   copybutton_prompt_is_regexp = True
   copybutton_remove_prompts = True  # (default)

2. Copy only lines with prompts, when it finds prompts:

   copybutton_only_copy_prompt_lines = True  # (default)

3. Copy multiple wrapped lines and re-assemble them, if the first one starts with a prompt:

   copybutton_line_continuation_character = "\\"

Full docs: https://sphinx-copybutton.readthedocs.io/

[tomasr8]

If there's still interest in having this feature, I can give it a go. I would suggest to use navigator.clipboard which has been supported by all major browsers for >5 years at this point.

We also already have a function which can strip the prompt markers from the code so the implementation (bar the UI) should be relatively simple.

[ferdnyc]

@tomasr8 That function also removes the output lines from interactive sessions, which I think is an important part of being able to copy/paste commands from those sessions.

If I might be permitted a bit of feature creep, I notice that the prompt characters in the listings are styled user-select: none so that they don't get caught up in manual copy actions.

Rather than having the "strip out the prompts and output" button, it might be easier to just style the output as non-selectable as well, so that even manual selects would only get the input lines. (The copy button could then copy only the same elements, automatically.)

It's not too useful if selecting and copying this:

>>> 2 + 2
4
>>> 50 - 5*6
20
>>> (50 - 5*6) / 4
5.0
>>> 8 / 5  # division always returns a floating-point number
1.6

gets you this on the clipboard:

2 + 2
4
50 - 5*6
20
(50 - 5*6) / 4
5.0
8 / 5  # division always returns a floating-point number
1.6

...Because without the prompts, that's completely confusing. Almost better to leave the prompts IN, than to end up with that. But better still, seems to me, if it gets you this:

2 + 2

50 - 5*6

(50 - 5*6) / 4

8 / 5  # division always returns a floating-point number

...which is what happens if you copy after activating the "remove prompts and output" button, but could just as easily happen automatically right from the start.

[ferdnyc]

(And the only thing required for things to work that way is adding div.highlight span.go to the user-select: none style rules already in place for div.highlight span.gp and others.)

[tomasr8]

(And the only thing required for things to work that way is adding div.highlight span.go to the user-select: none style rules already in place for div.highlight span.gp and others.)

One other place which might not be so simple is traceback text which does not have any easily selectable classes (it's currently handled in getHideableCopyButtonElements as well).