errors.CompositionError

A contracted transformation’s precondition on an input is not implied

Usage

errors.CompositionError(
    report,
    consumer,
    param,
    producer,
    guarantees,
)

by what the contracted transformation producing that input guarantees.

Import it from sverify.errors. It is raised when the link is built: when a transform is called on another contracted transformation’s result, or on a node (sverify.Node) built from one, stored or not. The message names both sides, for example “doubled needs (.amount >= 0) (it may be FALSE on some rows) on ‘t’; not_null only guarantees .amount.notnull()”. With on_unproved="check" and a bound input, the precondition is checked on the data instead; with on_unproved="warn" it is a warning.

Attributes

report: The Report of the failed proof of the link.
consumer: The name of the transformation whose precondition failed.
param: The parameter of consumer that received the input.
producer: The name of the contracted transformation that produced it.