this post was submitted on 21 Nov 2024
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Python allows programmers to pass additional arguments to functions via comments. Now armed with this knowledge head out and spread it to all code bases.

Feel free to use the code I wrote in your projects.

Link to the source code: https://github.com/raldone01/python_lessons_py/blob/main/lesson_0_comments.ipynb

Image transcription:

from lib import add

# Go ahead and change the comments.
# See how python uses them as arguments.

result = add()  # 1 2
print(result)
result = add()  # 3 4
print(result)
result = add()  # 3 4 5 20
print(result)

Output:

3
7
32
all 46 comments
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[–] shotgun_crab@lemmy.world 6 points 46 minutes ago

This is some javascript level shit

[–] arisunz@lemmy.blahaj.zone 20 points 3 hours ago

I fucking hate this, thanks OP

[–] MrPoopyButthole@lemmy.world 48 points 5 hours ago

That's disgusting

[–] RichardoC@lemmy.world 31 points 5 hours ago

Thank you, I hate it

[–] bdonvr@thelemmy.club 98 points 6 hours ago (6 children)

IMO comments should never ever be parsed under any circumstances but I probably don't know enough to really speak on this

[–] jedibob5@lemmy.world 38 points 6 hours ago

No, your intuition is correct, this is extremely cursed.

[–] perviouslyiner@lemmy.world 23 points 5 hours ago* (last edited 3 hours ago) (1 children)

Seen in a code review (paraphrased):

image of a program which is estimating the size of an array by counting how many lines of source code were used to construct it

"Why does this break when you add comments in the middle?"

[–] bleistift2@sopuli.xyz 7 points 4 hours ago (3 children)

Why would python even expose the current line number? What’s it useful for?

[–] raldone01@lemmy.world 7 points 2 hours ago* (last edited 2 hours ago)

On a serious note:

This feature is actually very useful. Libraries can use it create neat error messages. It is also needed when logging information to a file.

You should however never ever parse the source code and react to it differently.

[–] Dicska@lemmy.world 9 points 4 hours ago

You underestimate the power of us, print debuggers.

[–] hackerwacker@lemmy.ml 6 points 4 hours ago (1 children)

Why wouldn't it? Lots of languages do. In C++ you have __LINE__.

[–] ddplf@szmer.info 1 points 2 hours ago

Because it doesn't seem like a useful feature. The only occasion I imagine this could be helpful is with logging to the console to track when the function breaks, but even then - still trivial to replace.

[–] Badland9085@lemm.ee 2 points 3 hours ago

One case where I find it useful, tho it operates in a more limited way, is code in block blocks within code comments in Rust, which are also printed out in the generated documentation. They essentially get ran as part of your unit tests. This is great for making sure that, eg, your examples left in code comments actually work, especially if they’re written in a way that functions like a unit test.

[–] peereboominc@lemm.ee 1 points 3 hours ago

Some languages use the comments to generate documentation. Something like

// function to add two numbers func Add(num1 int, num2 int)

[–] bjorney@lemmy.ca 4 points 4 hours ago

The add function in the example above probably traverses the call stack to see what line of the script is currently being executed by the interpreter, then reads in that line in the original script, parses the comment, and subs in the values in the function call.

This functionality exists so when you get a traceback you can see what line of code triggered it in the error message

[–] balsoft@lemmy.ml 2 points 5 hours ago (1 children)

It's quite useful to parse comments and generate documentation from them, either as plain old hypertext or in your editor with LSP.

[–] ramble81@lemm.ee 2 points 4 hours ago

That sounds fine if you have something reading the file independently. But the actual executable code should not be able to access its own comments.

[–] embed_me@programming.dev 21 points 5 hours ago (2 children)

As if I needed more reasons to start away from python

[–] Chais@sh.itjust.works 11 points 5 hours ago

You can so stupid shit in any language. I admit Python doesn't exactly make it difficult. A bit like JS, but different.

[–] bjorney@lemmy.ca 5 points 4 hours ago (1 children)
[–] verdigris@lemmy.ml 2 points 3 hours ago* (last edited 15 minutes ago) (1 children)

Being able to get the line number is very different from comments being parsed.

Edit: didn't realize this was custom code built to be cursed.

[–] bjorney@lemmy.ca 7 points 2 hours ago* (last edited 2 hours ago) (1 children)

You should look at how OPs example works first maybe

The python interpreter isn't parsing comments, the add() function is just getting the current line number from the call stack context, and using a regex to spit out the numbers to the right of the "#" on the current executing line of the source code.

[–] verdigris@lemmy.ml 1 points 16 minutes ago

Yeah fair I was just assuming this was standard library, I see your point now.

[–] scrubbles@poptalk.scrubbles.tech 52 points 7 hours ago (1 children)

checks the community to make sure I'm in programmer humor

Yeah that checks out

[–] raldone01@lemmy.world 19 points 6 hours ago* (last edited 6 hours ago) (1 children)

You know that this is acutally working right??? 😊

Yup, just one of those posts that could of course work in either

[–] Ephera@lemmy.ml 24 points 6 hours ago (1 children)
[–] OsrsNeedsF2P@lemmy.ml 13 points 4 hours ago

Yup, the function actually goes and finds the code that calls it and parses the comment.

Disgusting.

[–] doeknius_gloek@discuss.tchncs.de 28 points 6 hours ago (3 children)

This does not actually work, right? Right?

[–] FourPacketsOfPeanuts@lemmy.world 21 points 5 hours ago* (last edited 5 hours ago) (1 children)
[–] tetris11@lemmy.ml 8 points 5 hours ago
[–] justcallmelarry@lemmy.dbzer0.com 33 points 6 hours ago* (last edited 6 hours ago) (1 children)

The add() function (that is available in the source code) basically uses some built in debugging tools to find out where in the code the function is called, and then parses the comment from the file and uses it for adding stuff.

I’ve never tried (becuse why would you…) but something similar can probably be built in any interpreted language

It’s not something Python does by design

[–] N0x0n@lemmy.ml 8 points 6 hours ago* (last edited 6 hours ago) (4 children)

Thanks :) ! Could you tell me what use case/purpose such function can have from a dev perspective?

[–] bjorney@lemmy.ca 5 points 4 hours ago

This stuff is normally used for creating human readable error messages. E.g. printing the line of your code that actually set off the exception

[–] McWizard@lemmy.zip 3 points 4 hours ago

We actually use method comments for user documentation as well. Only on specific business methods, but it's nice to have a good comment for the dev and a tooltip for the user at the same time.

[–] vort3@lemmy.ml 6 points 6 hours ago

I'd say nothing that can't be achieved by docstrings.

[–] justcallmelarry@lemmy.dbzer0.com 3 points 6 hours ago* (last edited 6 hours ago) (1 children)

This specific use case? To make a meme, mainly ¯\(ツ)

As for the components: Parsing comments have been used for stuff like type hints / formatting / linting, tho generally not at run time (afaik).

The tooling for finding out where something is called from can be used to give a better understanding of where things go wrong when an exception happens or similar, to add to logs.

I would say that in general you don’t need either functionality except for certain edge-usecases

[–] N0x0n@lemmy.ml 2 points 4 hours ago* (last edited 4 hours ago)

Thank you ! 😄

[–] FourPacketsOfPeanuts@lemmy.world 33 points 7 hours ago

Every day further from god's light etc...

[–] davel@lemmy.ml 5 points 4 hours ago (1 children)

What? There is no lib module.

$ python3.13 -c 'import lib'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import lib
ModuleNotFoundError: No module named 'lib'
$
[–] b34k@lemmy.ml 5 points 4 hours ago (1 children)

OP wrote this add() function and has provided their own lib module in the source code.

[–] davel@lemmy.ml 10 points 4 hours ago

Oh, so it’s not Python that’s cursed.

One of Python’s design philosophies is—or at least was—“we are all consenting adults here.” If you really want to turn Python into Brainfuck, the interpreter isn’t going to stop you.

[–] LolaCat@lemmy.ca 18 points 6 hours ago

I feel sick

[–] WILSOOON@programming.dev 6 points 6 hours ago

Why, just why

[–] muntedcrocodile@lemm.ee 6 points 6 hours ago

Makes sence if u think about it. We use comments as docstrings that the interpreter has an understanding of. Python lets u fuck with its internals (at least in an immutable manner) so why not fuck with comments.