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ducto.expr module

Safe expression evaluator using Python’s ast module.

Allows mathematical expressions with whitelisted variables and functions. Rejects any AST node type not in the allowlist (no eval/exec).

exception ducto.expr.ExpressionError​

Bases: Exception

Raised on invalid or unsafe expressions.

ducto.expr.evaluate_expression(expr: str, variables: dict[str, float | int]) → float​

Safely evaluate a validated expression.

Args: : expr: Expression string to evaluate. variables: Mapping of variable names to their numeric values.

Returns: : Numeric result of the expression evaluation.

Raises: : ExpressionError: If the expression is invalid or references : unknown variables.

ducto.expr.validate_expression(expr: str) → None​

Validate that an expression string is safe and syntactically valid.

Args: : expr: Expression string to validate.

Raises: : ExpressionError: If the expression contains disallowed constructs.