- exception psi4.driver.UpgradeHelper(old, new, version, elaboration)¶
Error called on previously valid syntax that now isn’t and a simple syntax transition is possible.
It is much preferred to leave the old syntax valid for a release cycle and have the old syntax raise a deprecation
FutureWarning. For cases where the syntax just has to jump, an UpgradeHelper can be used to trap the old syntax at first error and suggest the new.
An UpgradeHelper can also be used after the
FutureWarningdescribed above has expired. Then the body of the code can be deleted while the definition is preserved, and an UpgradeHelper called in place of the body to guide users with lagging syntax.