Source code for tt.errors.evaluation

"""Exception type definitions related to expression evaluation."""

from .base import TtError

[docs]class EvaluationError(TtError): """An exception type for errors occurring in expression evaluation. This exception type should be sub-classed and is not meant to be raised explicitly. """
[docs]class InvalidBooleanValueError(EvaluationError): """An exception for when an invalid truth or don't care value is passed. Here's an example where we attempt to evaluate a \ :class:`BooleanExpression <tt.expressions.bexpr.BooleanExpression>` with an invalid value passed through ``kwargs``:: >>> from tt import BooleanExpression >>> b = BooleanExpression('A or B') >>> b.evaluate(A=1, B='brian') Traceback (most recent call last): ... tt.errors.evaluation.InvalidBooleanValueError: "brian" passed as \ value for "B" is not a valid Boolean value """
[docs]class NoEvaluationVariationError(EvaluationError): """An exception type for when evaluation of an expression will not vary. Let's see an example where we attempt to make a :class:`TruthTable \ <tt.tables.truth_table.TruthTable>` from an expression that has no symbols nor variation in its results:: >>> from tt import TruthTable >>> t = TruthTable('1 or 0') Traceback (most recent call last): ... tt.errors.evaluation.NoEvaluationVariationError: This expression is \ composed only of constant values """