No Wishful Thinking
Guessing without knowing may be futile.
Consider web service
Withdraw
.
Has "balance" as input and output.
"Amount" to be withdrawn is a known input.
"Balance" is not known until runtime.
Precondition
is that
Balance > Withdrawal Amount
.
Whether that should be assumed may be determined by case.
But
Balance
should not be
Selectable
.
If
Balance
is required to be an exact amount,
and there is no way to make a sub-plan to make it so,
guessing that it is so is just futile.
This is needed even if you don't propagate property values.
Don't plan that you will win a Nobel Prize.
©2012
Charles Petrie
- permission to reproduce widely with attribution.
