LTAI Error handling (2)

"Let's Talk About It" solution:

System always generates error message at highest level of interaction

User is allowed to trace error source through abstracted application levels
(Error messages passed up 'command tree' reporting relative intention at each stage)

User is also allowed to inspect the state of the system at each level

Uses an eternalized library of error messages for each application

Eternalized error generator linked with application

Contrived example:

Scenario: desktop calculator

User types "n + =" without specifying the 2nd number

User/System dialogue:

SYS:"I cannot add two values, because there is only one value"
USER:"Why?"

SYS:"To get the two values, I needed to get the first value, which I did."
USER:"Then?"

SYS:"Then I needed to get the second value, but there is no more value."
USER:"Then?"

SYS: "To get the second value, I needed to check if there is any value in the workspace, but the workspace is empty."
USER: "Then?"

SYS: "That is all."