Recasting an object as a particular view

clinst · Dec 27, 2012

Lets start with the code

B4X:

Sub FillItems(Sel as String, ObjToFill As Object)

If ObjToFill Is Spinner Then
     Dim obj As Spinner
     obj = ObjToFill
Else If ObjToFill Is ListView Then
     Dim obj As ListView
     obj = ObjToFill
End If

... code ...

End Sub

I'm getting the error msg "Current declaration does not match previous one" occuring at the

B4X:

Dim obj As ListView

line.

Does B4A not allow this sort of thing or is there a proper way of doing this?

Erel · Dec 27, 2012

The problem is that you declared the same variable with two different types.

Change the code to:

B4X:

If ObjToFill Is Spinner Then
     Dim spn As Spinner = ObjToFill
Else If ObjToFill Is ListView Then
     Dim lst As ListView = ObjToFill
End If

clinst · Dec 27, 2012

I understand what you say but it doesn't fix the problem I'm afraid.

I am using the same variable so my code is shorter. ie instead of something like this:-

B4X:

If ObjToFill Is Spinner Then
     Dim spn As Spinner = ObjToFill
     ... code manipulating object ...
Else If ObjToFill Is ListView Then
     Dim lst as ListView = ObjToFill
     ... code manipulating object ...
End If

I wanted to do this:-

B4X:

If ObjToFill Is Spinner Then
     Dim obj As Spinner
Else If ObjToFill Is ListView Then
     Dim obj As ListView
End If

... code manipulating object

Ie Rather than having the manipulating code included a number of time (with all the issues with changes etc) I want it only include it once.

Erel · Dec 27, 2012

A variable can only be declared with one specific type.

You can create two classes (one for each type) and use CallSub to call a method that exists in both classes.

clinst · Dec 27, 2012

Fair enough

Any chance, in the future, this might be possible? My thinking comes from the way arrays are handled. If an array is dim'd again it just replaces the old array with the new one (as I understand it). The same is true for some functions, like messing with strings which just replace the old string with a new one.

Erel · Dec 27, 2012

You can redim a variable. However the variable type cannot be changed. The compiler must know the type during compilation.

Recasting an object as a particular view

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Recasting an object as a particular view

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