16f6c0aecf
Inline adoc files when they are included exactly once. Also fix language tags because this inlining gives us better information on what language the code is written in.
57 lines
1.6 KiB
Plaintext
57 lines
1.6 KiB
Plaintext
== Why is this an issue?
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A common anti-pattern is to check that a key exists in a dictionary before retrieving its corresponding value and providing a default value otherwise. This pattern works but is less readable than the equivalent call to the built-in dictionary method "get()" with a default value.
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Note that if a default value is set for every key of the dictionary it is possible to use python's defaultdict instead.
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This rule raises an issue when a key presence is checked before retrieving its value or providing a default value. It only raises an issue when the default value is a hard-coded string, number, list, dictionary or tuple. Computed values will not raise an issue as they can have side-effects.
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=== Noncompliant code example
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[source,python]
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----
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result = "default"
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if "missing" in mydict:
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result = mydict["missing"] # Noncompliant
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if "missing" in mydict:
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result = mydict["missing"] # Noncompliant
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else:
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result = "default"
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if "missing" in mydict:
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result = mydict["missing"] # Compliant. No issue is raised as generate_value() might have some side-effect.
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else:
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result = generate_value()
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----
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=== Compliant solution
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[source,python]
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----
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result = mydict.get("missing", "default")
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# OR, if "default" is the default value for every key
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from collections import defaultdict
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mydict = defaultdict(lambda: "default")
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result = mydict["missing"]
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----
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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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Replace this key check and dictionary access with a call to "get(..., default)"
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endif::env-github,rspecator-view[]
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