79 lines
2.2 KiB
Plaintext
79 lines
2.2 KiB
Plaintext
This rule raises an issue when strings or bytes are concatenated implicitly.
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== Why is this an issue?
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Python concatenates adjacent string or byte literals at compile time. It means that ``++"a" "b"++`` is equivalent to ``++"ab"++``.
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This is sometimes used to split a long string on multiple lines. However an implicit string concatenation can also be very confusing.
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In the following contexts it might indicate that a comma was forgotten:
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* when the two strings are on the same line. This could be interpreted as an incorrectly formatted tuple (parentheses are not mandatory to create a tuple, only the comma is).
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* when the strings are in a list, a set or a tuple.
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=== Code examples
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==== Noncompliant code example
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[source,python,diff-id=1,diff-type=noncompliant]
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----
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def func():
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return "item1" "item2" # Noncompliant: a comma is missing to return a tuple.
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["1" # Noncompliant: a comma is missing.
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"2",
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"a very" # Noncompliant: a "+" is missing.
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"long string"]
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----
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==== Compliant solution
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[source,python,diff-id=1,diff-type=compliant]
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----
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def func():
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return "item1", "item2"
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["1",
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"2",
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"a very" +
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"long string"]
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----
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=== Exceptions
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This rule will not raise any issues when there is a visible reason for the string concatenation:
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* when the quotes used for both strings are different. This can be used to avoid escaping quotes.
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* when the strings or bytes have different prefixes, i.e. "f" for f-strings, "r" for raw, "u" for unicode and no prefix for normal strings.
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* when strings are visibly split to avoid long lines of code, i.e. when the first string ends with a space, punctuation or ``++\n++``.
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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When the strings are on multiple lines:
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* "Add a "+" operator to make the string concatenation explicit; or did you forget a comma?"
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When the strings are on the same line:
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* "Merge these implicitly concatenated strings; or did you forget a comma?"
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=== Highlighting
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Primary: The end quote of the first concatenated string/bytes literal
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Secondary:
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* location: the starting quote of the next string/bytes/literal
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* no message
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endif::env-github,rspecator-view[]
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