Quantities and Units

I am implementing a model defined with quantity data having {value,
multiplier, unit} where
multiplier is  m, c, k, M, etc
unit is V, A, Hz, W, etc

So I am looking for what quantities/units packages are around before
trying to write my own.

I have downloaded [1] and had a poke around there with the tests.  Are
there any further examples around of how to use it and to define new
units?  I notice that Voltage=Joules/Columb is not defined.

Is anyone have any familiar with ports of packages mentioned here [2]
[3] [4] from other platforms?

cheers, Ben

[1] http://www.squeaksource.com/Units.html
[2] http://www.cincomsmalltalk.com/publicRepository/Quantities.html
[3] http://www.smalltalking.net/goodies/Dolphin/ (scroll to bottom)
[4] http://comments.gmane.org/gmane.comp.lang.smalltalk.squeak.general/55894

Hi Ben,

Gabriel Cotelli wrote: nice to have a detailed background on this. So now I have Aconcagua
installed and am experimenting setting up units 'newton' and 'joule' as
shown in the code at the bottom of this post.  Now line 008 (called from
line 016) is failing since line 010 tries to find 'newton' in the
'units' dictionary but cannot since it was stored instead by line 014 as
key: 'meter.kilogram/second^2' - due to line 006 as shown in the
attached image [1] - which is due to 'name' calling 'nameForOne' which
is...
    DividedUnit>>nameForOne
        ^numerator name asString , '/' , denominator name asString

I then noticed that section Future Work of the paper says "We have not
implemented any kind of functionality to allow well known composed units
to be named, such as Joule (equivalent to m*m*Kg/s*s )."   Has anyone
else progressed "named composed units" since 2005?

For my try, the closest example I found is method
'UnitsTestResource>>createMinute' which ultimately works because method
'name'  fulfilled by...
    ProportionalDerivedUnit>>nameForOne
        ^nameForOne        
where the instanceVariable 'nameForOne' is set at object creation.

I could add a similar instanceVariable to DividedUnit and perhaps have...
    DividedUnit>>nameForOne
       nameForOne
            ifNil: [^numerator name asString , '/' , denominator name
asString]
            ifNotNil: [ ^nameForOne ].

but I'm not sure what that might break... Any advice would be appreciated.

cheers, Ben

[1] DividedUnit Inspector on Newton.png


Code reference for above discussion...
----
"Based on UnitsTestResource>>setup have the following code to implement
units 'newton' and 'joule'  "
"Naming"
"001" UnitsTestResource>>newtonName  
"002"     ^'newton'          
"003" UnitsTestResource>>jouleName      
"004"     ^'joule'
"Creating"
"005" UnitsTestResource>>createNewton    
"006"     ^(self kilogram * self meter) / ( self second * self second)
"007" UnitsTestResource>>createJoule    
"008"     ^(self newton) * (self meter)
"Accessing"
"009" UnitsTestResource>>newton        
"010"    ^units at: self newtonName
"011" UnitsTestResource>>joule      
"012"    ^units at: self jouleName
---
"and where existing addUnit is defined as..."
"013" UnitsResource>>addUnit: aUnit
"014"     units at: aUnit name put: aUnit.      "units is a Dictionary"
"I appended the following to existing UnitsTestResource>>setup..."
"015"         self addUnit: self createNewton.
"016"         self addUnit: self createJoule.
---
"as a reference for creating a named unit there is existing..."
"017 UnitsResource>>createMinute
"018"     ^ProportionalDerivedUnit baseUnit: self second
conversionFactor: 60 named: self minuteName
----