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Andrew Brault's Units Package for Squeak 2.8/2.9a

The Units package allows you to represent, convert, and perform arithmetic with physical unit values (e.g. distances, velocities, accelerations, etc).

There is not much formal documentation, but most of the classes in this package have comments. The most important methods are those in Unit and UnitValue. You should look through all those.

To add your own units, see the classes BaseUnit, DerivedUnit, NamedUnit, and PrefixedUnit, and look through the initialization code. You should duplicate what is done there to add your own units. Remember to send Unit initialize to make your changes take effect.

Note that you can send  Unit printAbbreviated: true  or  Unit printAbbreviated: false  to control how units print.

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• System Modification Details

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License

A copy of his message is provided below:

Date: Thu, 4 Mar 1999 13:29:30 -0500 (EST)
From: Andrew Brault <ajb@...>
To: Helge Horch <Helge.Horch@...>
Subject: Re: [ANN] Units for Squeak

On Thu, 4 Mar 1999, Helge Horch wrote:
> Folks,
>
> I have finished porting Andrew Braults Units package for Squeak. The
> current version is available at

Very cool!  Thanks!
BTW you have my permission to remove the "giftware"
notice from the Squeak port and add whatever licensing
terms are appropriate for Squeak.

-ajb

'Create unit values by sending #units: to a number.'
2 units: #inches.
  2 inches

'You can add, divide, multiply, and subtract unit values.'
(2 units: #inches) / (3 units: #seconds).
  (2/3) inches per second

'Adding or subtracting units does appropriate conversions.'
(14 units: #feet) + (10 units: #meters).
  46.8083989501312 feet

'You can also explicitly convert values.'
(15 units: #miles) / (1 units: #hours)
	convertTo: (Unit meters / Unit seconds).
  6.7056 meters per second

'You can use 'derived' units such as the newton.'
3 units: #newtons.
  3 newtons

'You can expand such a value into base SI units.'
(3 units: #newtons) baseUnits.
  3000 gram meters per square second

'To see kilograms rather than grams, factor with respect to kilograms.'
(3 units: #newtons) factor: Unit kilograms.
  3 kilogram meters per square second

'Unit values can also be compared (provided they are dimensionally consistent.'
(1 units: #inches) < (3 units: #centimeters).
  true

"Creating additional units is easy:"
| microfortnight |
microfortnight := PrefixedUnit
	prefixName: 'micro'
	unit: (DerivedUnit
			abbreviation: 'FN'
			name: 'fortnight'
			pluralName: 'fortnights'
			value: (14 units: #days)).
(1 units: microfortnight) baseUnits "value asFloat"
  (756/625) seconds

All faults and bugs are probably mine, so I highly welcome feedback and bug reports. The changeset is provided as-is, use this software at your own risk. No warranty of fitness for any purpose is claimed, implicitly or otherwise. There are a few minor changes to the base classes:

• both SmallInteger>>/ and Float>>/ now send #isZero instead of = 0
• Number>>units: is used to make UnitValues

• replaces #anySatisfy: with #contains:
• adds Number>>isZero back
• replaces the exception references in SmallInteger>>/ and Float>>/ with self error: 'division by zero'