57 lines
1.7 KiB
Plaintext
57 lines
1.7 KiB
Plaintext
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Python does not check returned types by default, however some methods are expected to return a specific type otherwise builtin functions will fail. Developers can also use type hints to specify which types they expect. Not following these type hints will most probably result in a runtime error.
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This rule raises an issue when a function or method:
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* does not return or yield a value of the expected type.
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* returns a value when no value should be returned.
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* returns no value when a return value is expected.
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== Noncompliant Code Example
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----
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class MyInt:
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def __init__(self):
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return self # Noncompliant. __init__ should return nothing. This will raise a TypeError.
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def __int__(self):
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return 3.0 # Noncompliant. __int__ should always return an integer
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int(MyInt()) # This will fail with "TypeError: __int__ returned non-int (type float)"
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def hello() -> str:
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return 42 # Noncompliant. Function's type hint asks for a string return value
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def should_return_a_string(condition) -> str:
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if condition:
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return "a string"
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# Noncompliant. The function returns None if the condition is not met
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def generator_noncompliant() -> Generator[int, float, str]:
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sent = yield '42' # Noncompliant
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return 42 # Noncompliant
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----
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== Compliant Solution
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----
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class MyInt:
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def __int__(self):
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return 3
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int(MyInt())
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def hello() -> str:
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return "Hello"
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def should_return_a_string() -> str:
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return "a string"
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def generator_ok() -> Generator[int, float, str]:
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sent = yield 42
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return '42'
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----
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== See
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* https://docs.python.org/3/library/typing.html[Python documentation - Support for type hints]
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* https://docs.python.org/3/reference/datamodel.html#special-method-names[Python documentation - Special method names]
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