56 lines
1.6 KiB
Plaintext
56 lines
1.6 KiB
Plaintext
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This rule raises an issue when "f-strings" are deeply nested.
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== Why is this an issue?
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Through https://peps.python.org/pep-0701/[PEP 701], Python 3.12 lifts restrictions on how to construct "f-strings".
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Prior to Python 3.12, it was not possible to reuse string quotes when nesting "f-strings". Therefore, the maximum level of nesting was:
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[source,python]
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----
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f"""{f'''{f'{f"{1+1}"}'}'''}"""
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----
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It is now possible to arbitrarily nest "f-strings" by reusing string quotes. The following snippet is therefore valid:
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[source,python]
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----
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f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}"
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----
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It is, however, not recommended to nest "f-strings" too deeply as this would make the code confusing and hard to maintain.
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This rule will raise an issue when "f-string" literals are nested 3 times or more.
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== How to fix it
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To fix this issue, refactor the code to avoid nesting "f-string" literals too deeply. This may be done by introducing new variables to store intermediate results.
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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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hello = "Hello"
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name = "John"
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my_string = f"{f"{f"{hello}"},"} {name}!" # Noncompliant: deep nesting of "f-strings" is confusing
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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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hello = "Hello"
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name = "John"
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greeting = f"{f"{hello}"},"
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my_string = f"{greeting} {name}!" # Compliant
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----
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== Resources
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=== Documentation
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* PEP 701 - https://peps.python.org/pep-0701/[Syntactic formalization of "f-strings"]
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* Python Release Notes - https://docs.python.org/3/whatsnew/3.12.html#what-s-new-in-python-3-12[What’s New In Python 3.12]
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