[cap-talk] Potting the web-calculus in a paragraph
smagi at naasking.homeip.net
Fri Dec 16 12:45:40 EST 2005
Bill Frantz wrote:
>On 12/15/05, smagi at naasking.homeip.net (Sandro Magi) wrote:
>>So a brand can be likened to a class. Can anyone elaborate on the
>>differences from a class?
>In general, class is a compile-time notion. Brands are more run-time.
>One place I have seen brands used is in digital money demos. You define
>a class called purse. Each type of currency (think Euro, Dollar etc.)
>has its own brand. Purses can transfer funds between themselves if they
>are of the same currency. They use brands to identify whether the other
>purse in a transfer has the same currency. While two purses with
>different brands are instances of the same class, the brand difference
>means they represent different currencies.
Thanks for the clarification.
This sounds like units in measurement, where a Measurement is a class
whose instances encapsulate a numeric quantity and units; certain
operations generate a new set of units (ie. division), and certain other
operations (ie. comparison) is only possible between measurements with
the same units.
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