PY-EXCE0001 · broad_try_literal_setup

Count literal local setup assignments needlessly protected by a broad try.

This is a deterministic rule for python. Read its implementation.

Definition

Inspect ordinary try statements inside functions. Report a try when its body starts with one or more assignments of a literal ast.Constant to one simple local name, another body statement follows, and that next statement contains an explicit operation that can raise. Calls, imports, attribute or subscript access, arithmetic, comparison, assertion, raising, iteration, context management, and awaiting are the exact protected-operation set. Moving the literal assignments immediately before the try narrows which failures the handlers catch.

Evidence

Each finding identifies every movable local name, the exact source range of the leading setup, and the first protected operation. No automatic edit is offered because comments and the indentation of a compound statement require a concrete-syntax transformation. The value is the number of try regions opening with movable literal setup.

Exceptions

Abstain at module or class scope, for try statements with finally, for exception-group try*, and when a candidate name is declared global or nonlocal. Annotated, chained, destructuring, attribute, subscript, computed, or type-commented assignments are not proven non-raising. A try containing only literal setup and a non-raising return is not reported.

Examples

Bad

try:
    mode = "rb"
    payload = stream.read()
except OSError:
    recover()

Good

mode = "rb"
try:
    payload = stream.read()
except OSError:
    recover()

Keep a computed setup expression inside when evaluating it belongs to the recovery boundary.

References

• Cites “The Python Tutorial”, Handling Exceptions. Open reference
• Cites “The Python Language Reference”, the try statement. Open reference
• Cites “Clean Code in Python”, Error Handling