Hello,

This is probably more of a design question rather than a specific question about vb6.

I’m creating a class module with a number of property let and property get variables. The property let variables are used in a fairly complex spring formula and the output will be property get variables.

e.g.

Public Property Let TubeODInMM(TubeODInMM As Single)
vTubeODInMM = TubeODInMM
End Property
Public Property Let CurtainSectionThkInMM(CurtainSectionThkInMM As Single)
vCurtainSectionThkInMM = CurtainSectionThkInMM
End Property
Public Property Let CurtainWidthInMM(CurtainWidthInMM As Single)
vCurtainWidthInMM = CurtainWidthInMM
End Property

Public Property Get TorqueClosed()
TorqueClosed = vTorqueClosed
End Property
Public Property Get TorqueOpened()
TorqueOpened = vTorqueOpen
End Property
Public Property Get RadiusClosed()
RadiusClosed = vRadiusClosed
End Property
Public Property Get RadiusOpened()
RadiusOpened = vRadiusOpened
End Property

From a design point of view, is it better to let the user of the object set the input properties; execute a GetSpring() method and then read the output properties e.g.

Dim objSpring as New clsSpring

ObjSpring.TubeODInMM=127
ObjSpring.CurtainWidthInMM =2400
Etc.
ObjSpring.GetSpring()
VRadiusClosed= ObjSpring.RadiusClosed
VRadiusOpened= ObjSpring.RadiusOpened
Etc.

or set the input properties and automatically run internally in the object GetSpring() procedure when the user selects a output property e.g.

Dim objSpring as New clsSpring

ObjSpring.TubeODInMM=127
ObjSpring.CurtainWidthInMM =2400
Etc.
VRadiusClosed= ObjSpring.RadiusClosed
VRadiusOpened= ObjSpring.RadiusOpened
Etc.

Inside the class
Public Property Get TorqueClosed()
    Call GetSpring()
TorqueClosed = vTorqueClosed
End Property

Thanks

hi there...

My point of view: if you call getspring in every property you will call it maybe more times that is needed, because if you want to read all the values you will call it every time it tries to read...

I prefer the first method: let the user call getspring and them let him choose which data he want.

HTH

Gonzalo

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tough question.
Forcing the caller to call a method before accessing the output parameter can bring bad code errors.
You can use an internal variable (boolean) that is set to true every time a property changes, like

public property let ff(c)
m_changed = (c <> m_c)

and then in every property get you call GetSpring if m_changed is true (and set m_changed to false). In this way you call GetSpring only once, and the caller does not have to take any action

Personally, I prefer to have the caller to call explicitally a method to apply the new properties, like you are doing now

"There are two ways to write error-free programs. Only the third one works."
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Thank you both for your replies. I'll design the code based on your answers!