53 lines
1.1 KiB
Bash
53 lines
1.1 KiB
Bash
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#!/usr/bin/env bash
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#
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# Copyright (c) 2019 The Bitcoin Core developers
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# Distributed under the MIT software license, see the accompanying
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# file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#
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# Detect when a mutable list or dict is used as a default parameter value in a Python function.
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export LC_ALL=C
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EXIT_CODE=0
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OUTPUT=$(git grep -E '^\s*def [a-zA-Z0-9_]+\(.*=\s*(\[|\{)' -- "*.py")
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if [[ ${OUTPUT} != "" ]]; then
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echo "A mutable list or dict seems to be used as default parameter value:"
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echo
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echo "${OUTPUT}"
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echo
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cat << EXAMPLE
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This is how mutable list and dict default parameter values behave:
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>>> def f(i, j=[], k={}):
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... j.append(i)
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... k[i] = True
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... return j, k
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...
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>>> f(1)
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([1], {1: True})
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>>> f(1)
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([1, 1], {1: True})
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>>> f(2)
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([1, 1, 2], {1: True, 2: True})
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The intended behaviour was likely:
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>>> def f(i, j=None, k=None):
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... if j is None:
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... j = []
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... if k is None:
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... k = {}
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... j.append(i)
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... k[i] = True
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... return j, k
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...
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>>> f(1)
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([1], {1: True})
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>>> f(1)
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([1], {1: True})
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>>> f(2)
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([2], {2: True})
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EXAMPLE
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EXIT_CODE=1
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fi
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exit ${EXIT_CODE}
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