CodeQL documentation

Deprecated slice method

ID: py/deprecated-slice-method
Kind: problem
Severity: warning
Precision: very-high
Tags:
   - maintainability
Query suites:
   - python-security-and-quality.qls

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The __getslice__, __setslice__ and __delslice__ methods have been deprecated since Python 2.0. In general, no class should implement these methods.

The only exceptions to this rule are classes that inherit from list and override __getitem__, __setitem__ or __delitem__. Since list implements the slicing methods any class inheriting from list must implement the the slicing methods to ensure correct behavior of __getitem__, __setitem__ and __delitem__. These exceptions to the rule will not be treated as violations.

Recommendation

Delete the slicing method. Any functionality should be moved to the equivalent __xxxitem__ method:

  • __getslice__ should be replaced with __getitem__
  • __setslice__ should be replaced with __setitem__
  • __delslice__ should be replaced with __delitem__

References