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Add notes about s[i] in Common Sequence Operations #134976

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Yzi-Li opened this issue May 31, 2025 · 4 comments
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Add notes about s[i] in Common Sequence Operations #134976

Yzi-Li opened this issue May 31, 2025 · 4 comments
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@Yzi-Li
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Yzi-Li commented May 31, 2025 •
edited by bedevere-app bot
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Documentation

Operation Result Notes
s[i] ith item of s, origin 0 (3)
  1. If i or j is negative, the index is relative to the end of sequence s: len(s) + i or len(s) + j is substituted. But note that -0 is still 0.

We can add a note: If the sequence is empty or i is outside the sequence range, IndexError will be raised.

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@Yzi-Li Yzi-Li added the docs Documentation in the Doc dir label May 31, 2025
@bedevere-app bedevere-app bot mentioned this issue May 31, 2025
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@picnixz
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picnixz commented May 31, 2025

I'm surprised that there is nothing about IndexError on this page

@terryjreedy
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I believe that while negative indexes are implemented for (most?) builtins, this is not necessarily the case for all sequences.

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picnixz commented May 31, 2025 •
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Note (3) still says:

If i or j is negative, the index is relative to the end of sequence s: len(s) + i or len(s) + j is substituted. But note that -0 is still 0.

So the common sequence operations assume that negative indices should be supported by arbitrary sequences.

picnixz pushed a commit that referenced this issue Jun 8, 2025
@Yzi-Li
gh-134976: document the exception type that can be raised by s[i] (#…
158e516 
…134977)
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Jun 8, 2025
@Yzi-Li @miss-islington
pythongh-134976: document the exception type that can be raised by `s…
1b6b15c 
…[i]` (pythonGH-134977)

(cherry picked from commit 158e516)

Co-authored-by: Yongzi Li <204532581+Yzi-Li@users.noreply.github.com>
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Jun 8, 2025
@Yzi-Li @miss-islington
pythongh-134976: document the exception type that can be raised by `s…
45dc45f 
…[i]` (pythonGH-134977)

(cherry picked from commit 158e516)

Co-authored-by: Yongzi Li <204532581+Yzi-Li@users.noreply.github.com>
This was referenced Jun 8, 2025
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Merged
picnixz pushed a commit that referenced this issue Jun 8, 2025
@miss-islington @Yzi-Li
[3.14] gh-134976: document the exception type that can be raised by `…
483a462 
…s[i]` (GH-134977) (#135258)

gh-134976: document the exception type that can be raised by `s[i]` (GH-134977)
(cherry picked from commit 158e516)

Co-authored-by: Yongzi Li <204532581+Yzi-Li@users.noreply.github.com>
picnixz pushed a commit that referenced this issue Jun 8, 2025
@miss-islington @Yzi-Li
[3.13] gh-134976: document the exception type that can be raised by `…
47a828e 
…s[i]` (GH-134977) (#135259)

gh-134976: document the exception type that can be raised by `s[i]` (GH-134977)
(cherry picked from commit 158e516)

Co-authored-by: Yongzi Li <204532581+Yzi-Li@users.noreply.github.com>
@picnixz
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picnixz commented Jun 8, 2025

Thank you!

@picnixz picnixz closed this as completed Jun 8, 2025
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