referencing members of UDTs

[smydo]

Hi,

I'm having a headache trying to assign a variable that will reference a member of a user defined type, i.e

i've designed the type thus:

public type Details
A as variant
B as variant
......(so on and so forth)
end type

later in the programme I want to reference particular members of an instance of this type depending on a case statement; my idea is to set a variable that will be set for each Case e.g

case 1
variable = "A"
case 2
variable = "B"
etc

i then try to reference the member like:

if Details.variable = 0 then
....

it doesn't work and throws the error: 'Method or data member not found.' Is there any way you can reference a data member in this manner??

[si_the_geek]

I'm afraid I dont understand what you are trying to do, hopefully this will help you!

a Type is basically a data type (like String, or Integer), but it contains one or more data types.

So with your Details type you could do the following:

Dim my_var as Details
my_var.A = "hello"
my_var.B = 37
 
....
 
If my_var.B = 0 Then
  Msgbox "B is 0"
End If

[Bombdrop]

You can not use a UDT as you wish if you want to use a select case with a UDT it has to be something like this.

Option Explicit
Private Type test
x As String
y As Integer
End Type
 
Private q As test
Private Sub Command1_Click()
    Select Case q.x
        Case Is = 3
            MsgBox "cought it"
        Case Else
            MsgBox "not there"
    End Select
 
End Sub
 
Private Sub Form_Load()
    q.x = "bombdrop"
    q.x = 2
End Sub

Hope this helps

[smydo]

thanks Si but maybe I've made it sound more complicated than it is: all I want is to be able to use a variable that will identify which member of Details i want to get the value of, like say I want Details.A but I'm only going to know at runtime that i want "A" so for different situations I may want "B" or "C" etc, that's why I created the variable in the Case statements.

I would like to be able to reference the members dynamically by saying:

.....Details.variable.....

Hope that's a little clearer

[si_the_geek]

I'm afraid that's not possible using a Type, this is roughly equivalent tho:

Dim fred as Details
....
 
Select Case ....
case 1
   variable = fred.A
case 2
   variable = fred.B
...
 
if variable = 0 then

It sounds as though an Array could well be more appropriate in this case.

[smydo]

I was afraid you fellas would say that - I'll come up with some other work around.

Cheers though

[Bombdrop]

how about this

Option Explicit
 
Enum testType
x
y
End Enum
 
Private Type test
x As String
y As Integer
End Type
 
Private q As test
Private GetType As testType
Private Sub Form_Load()
    'Add the values in the UDT
    List1.AddItem x
    List1.AddItem y
 
    q.x = "bombdrop"
    q.y = 2
End Sub
 
Private Sub List1_Click()
    'on click assign the select listitem to then enum
    Dim i As Integer
    i = CInt(List1.Text)
    GetType = i
    Select Case GetType
 
        Case x
            MsgBox q.x
 
        Case y
            MsgBox q.y
 
    End Select
 
 
End Sub

hope this helps

[frigginjerk]

you should use a enumeration instead of a udt

[Mc Brain]

VB -> Using Objects

You need a class and a collection to do something like what you want.

[Mc Brain]

Try this

[Bombdrop]

I'm not sure the Class/collection route is need I stil believ my second pice of code is more in tune with what the poster whats.
The attached shows a cleaner version of my previous post.

[Mc Brain]

Sorry, but I think my approach is nicer. You're not using a "variable" to get to the member the user wants, but a select case to show one or other member. I think.... your code does not fit what smydo needs. But this is something he could only answer because your approach might fit perfectly on what he is doing.