cython/cython

Coercing a sliced C array to Python should create a list

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#2,159 opened on Mar 17, 2018

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 (3 comments) (0 reactions) (0 assignees)Python (1,517 forks)batch import
Cython Language FeatureType Analysisenhancementgood first issuehelp wanted

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Description

Cython already copies a C array into a Python list automatically on object coercion. It should do the same for sliced C arrays, e.g.

def test():
    cdef int i
    cdef int a[100]
    for i in range(100):
        a[i] = i**2
    return a[:20]  # rejected by type analysis

Currently results in Cannot convert 'int *' to Python object.

Contributor guide

Research direction
Examine Cython's type analysis for C array slicing and object coercion. Identify the location in the code where conversions are defined and extend it to handle sliced arrays.
Tech stack
python
Domain
tooling
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
PythonCython
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65