Currently there are some anomalies in the Quantity package. The current package does not properly distinguish between date/time/datetime and other kinds of quantities. Date/times are not 'amounts', so the + and - operators should not be defined.
On an 'amount', the + and - operators are defined as in normal maths, i.e. stuff + more stuff = stuff and stuff - some stuff = less stuff. No matter what you do, you only have one type of stuff - like a lump of clay that you pull apart and stick together.
Date/times on the other hand (but not durations) are 'offsets' from an origin, and + and - don't make sense (you can't add two dates, two times, or two date/times; you can subtract them, but you don't end up with the same kind, you get a duration).
The general nature of the change needed is therefore to properly distinguish 'normal' quantities from Date, Time and Date/Time. This will simplify the model and software implementations based on it, while losing no semantics.
Activity
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Fixed
Details
Assignee
JeffJ
JeffJ
Reporter
JeffJ
JeffJ
Priority
Minor
Created February 1, 2007 at 12:00 AM
Updated February 26, 2007 at 12:00 AM
Resolved February 26, 2007 at 12:00 AM
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Minor
Currently there are some anomalies in the Quantity package. The current package
does not properly distinguish between date/time/datetime and other kinds of
quantities. Date/times are not 'amounts', so the + and - operators should not be
defined.
On an 'amount', the + and - operators are defined as in normal maths,
i.e. stuff + more stuff = stuff and stuff - some stuff = less stuff.
No matter what you do, you only have one type of stuff - like a lump of clay
that you pull apart and stick together.
Date/times on the other hand (but not durations) are 'offsets' from an origin,
and + and - don't make sense (you can't add two dates, two times, or two
date/times; you can subtract them, but you don't end up with the same kind,
you get a duration).
The general nature of the change needed is therefore to properly distinguish
'normal' quantities from Date, Time and Date/Time. This will simplify the model
and software implementations based on it, while losing no semantics.