Measurements Unit Conversion - Structure of Class in VB.net
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29-10-2019 - |
Question
I'm working on a Unit Conversion Module. I've found several good ideas here, as well as on CodeProject. My code looks very similar to this C# code at http://www.codeproject.com/KB/cs/Unit_Conversion_Sample.aspx From the following you'll probably gather that I'm pretty new to programming:)
I've created a Units base class that I inherit to create each unit type.
Public Class Units
Private _unitvalue As Double
Private _unittype As [Enum]
Public Sub New(UnitValue As Double, UnitType As [Enum])
_unitvalue = UnitValue
_unittype = UnitType
End Sub
Public Property UnitValue() As Double
Get
Return _unitvalue
End Get
Set(value As Double)
_unitvalue = value
End Set
End Property
Public Property UnitType() As [Enum]
Get
Return _unittype
End Get
Set(value As [Enum])
_unittype = value
End Set
End Property
Public Overrides Function ToString() As String
Return String.Format("{0} {1}", UnitValue.ToString(), UnitType.ToString())
End Function
End Class
I then inherit this class to start creating Units with a Unit conversion function included.
Public Class WeightUnit
Inherits Units
Enum WeightSym
'Pounds
Lbs
'Kilograms
Kg
End Enum
Sub New(UnitValue As Double, UnitType As WeightSym)
MyBase.New(UnitValue, UnitType)
End Sub
Public Function Convert(toUnit As WeightSym) As WeightUnit
'Base Weight Unit is Lbs
Dim fromUnit As WeightSym
fromUnit = UnitType
Dim Lbs As Double = 0
Select Case fromUnit
'Standard
Case WeightSym.Lbs
Lbs = UnitValue
Case WeightSym.Kg
Lbs = UnitValue * 2.2046226
End Select
Dim toVal As Double = 0
'to unit based on Lbs
Select Case toUnit
'Standard
Case WeightSym.Lbs
toVal = Lbs
Case WeightSym.Kg
toVal = Lbs * 0.4535924
End Select
Return New WeightUnit(toVal, toUnit)
End Function
End Class
I need to create several different Unit types, such as Length, Pressure, etc. This is working well except for one issue. I'd like to be able to change the UnitType, and automatically update the UnitValue. Such that if the Unit object has a value of 1 and a type of Inch, and the type is changed to Cm, the value would update to 2.54.
Something like this.... I've seen examples of this, but the difference here is that, I can't specify the Covert function in my base class because it changes with each new UnitClass I create.
Public Property UnitType() As [Enum]
Get
Return _unittype
End Get
Set(value As [Enum])
_unittype = value
_unitvalue = Convert(value).UnitValue
End Set
End Property
I tried making the Property UnitType Overridable and creating a new Override Property for UnitType in each UnitClass that I created, but I failed to get that to work.
Any suggestions are much appreciated. Thanks much!
No correct solution