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Merged
merged 1 commit into from
Jun 30, 2025
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gh-131885: update documented signatures for csv.{writer,reader} #136085

merged 1 commit into from
Jun 30, 2025

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adamtheturtle
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@adamtheturtle adamtheturtle commented Jun 29, 2025 •
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…ter` have some positional-only arguments

import csv

with open("example.csv", "w", newline='') as csvfile:
    csv.writer(csvfile=csvfile)  # TypeError:  expected at least 1 argument, got 0
import csv

csv.reader(csvfile="a")  # TypeError:  expected at least 1 argument, got 0

📚 Documentation preview 📚: https://cpython-previews--136085.org.readthedocs.build/

@adamtheturtle
pythongh-131885: �Update csv.rst to describe that csv.reader and `c…
5ddc2ff 
…sv.writer` have some positional-only arguments


```python
import csv

with open("example.csv", "w", newline='') as csvfile:
    csv.writer(csvfile=csvfile)  # TypeError:  expected at least 1 argument, got 0
```

```python
import csv

csv.reader(csvfile="a")  # TypeError:  expected at least 1 argument, got 0
```
@bedevere-app bedevere-app bot added awaiting review docs Documentation in the Doc dir skip news labels Jun 29, 2025
@github-project-automation github-project-automation bot moved this to Todo in Docs PRs Jun 29, 2025
@bedevere-app bedevere-app bot mentioned this pull request Jun 29, 2025
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LGTM.

Reading the source, I was a little confused at first:

cpython/Modules/_csv.c

Lines 1090 to 1100 in bd928a3

if (!PyArg_UnpackTuple(args, "reader", 1, 2, &iterator, &dialect)) {
Py_DECREF(self);
return NULL;
}
self->input_iter = PyObject_GetIter(iterator);
if (self->input_iter == NULL) {
Py_DECREF(self);
return NULL;
}
self->dialect = (DialectObj *)_call_dialect(module_state, dialect,
keyword_args);

PyArg_UnpackTuple unpacks positional arguments, so I would have thought that csv.writer(file, dialect="...") wouldn't work, but the catch is that _call_dialect checks if the dialect was non-NULL, and extracts it from the keywords if it is. But, there's nothing similar for csvfile, so this is the correct description for the docs.

@picnixz picnixz changed the title gh-131885: Update csv.rst to describe that csv.reader and `csv.wri… gh-131885: update documented signatures for csv.{writer,reader} Jun 29, 2025
@ZeroIntensity ZeroIntensity added needs backport to 3.13 bugs and security fixes needs backport to 3.14 bugs and security fixes labels Jun 30, 2025
@ZeroIntensity ZeroIntensity merged commit 75f4059 into python:main Jun 30, 2025
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Thanks @adamtheturtle for the PR, and @ZeroIntensity for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

@github-project-automation github-project-automation bot moved this from Todo to Done in Docs PRs Jun 30, 2025
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Jun 30, 2025
@adamtheturtle @miss-islington
pythongh-131885: Update documented signatures for `csv.{writer,reader…
2013f28 
…}` (pythonGH-136085)

(cherry picked from commit 75f4059)

Co-authored-by: Adam Dangoor <[email protected]>
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Jun 30, 2025
@adamtheturtle @miss-islington
pythongh-131885: Update documented signatures for `csv.{writer,reader…
85ac14b 
…}` (pythonGH-136085)

(cherry picked from commit 75f4059)

Co-authored-by: Adam Dangoor <[email protected]>
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bedevere-app bot commented Jun 30, 2025

GH-136120 is a backport of this pull request to the 3.14 branch.

@bedevere-app bedevere-app bot removed the needs backport to 3.14 bugs and security fixes label Jun 30, 2025
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bedevere-app bot commented Jun 30, 2025

GH-136121 is a backport of this pull request to the 3.13 branch.

@bedevere-app bedevere-app bot removed the needs backport to 3.13 bugs and security fixes label Jun 30, 2025
@adamtheturtle adamtheturtle deleted the patch-3 branch June 30, 2025 13:33
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Thanks!

ZeroIntensity pushed a commit that referenced this pull request Jun 30, 2025
@miss-islington @adamtheturtle
[3.13] gh-131885: Update documented signatures for `csv.{writer,reade…
ad5f88e 
…r}` (GH-136085) (GH-136121)

gh-131885: Update documented signatures for `csv.{writer,reader}` (GH-136085)
(cherry picked from commit 75f4059)

Co-authored-by: Adam Dangoor <[email protected]>
ZeroIntensity pushed a commit that referenced this pull request Jun 30, 2025
@miss-islington @adamtheturtle
[3.14] gh-131885: Update documented signatures for `csv.{writer,reade…
ed7719a 
…r}` (GH-136085) (GH-136120)

gh-131885: Update documented signatures for `csv.{writer,reader}` (GH-136085)
(cherry picked from commit 75f4059)

Co-authored-by: Adam Dangoor <[email protected]>
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