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Read private variables between forms

P: n/a
Hello,
who gives one more shining solution to me?
My application load form "A". The form "A" by means of a push-button load
form "B" that in its turn by means of a push-button load form "C". Form "B"
contains one variable "Private"
"VarB". How I can read the value of "VarB" from form "C"? All
the form come loaded with the following brace of instructions:

Sub Button2_Click(ByVal sender As System.Object, ByVal and As
System.EventArgs) Handles Button2.Click
Dim frm As New frm<A/B/C >
frm.ShowDialog()
End Sub
In form "B" have declared a Property "RetVarB" that encapsulates the value
of "VarB".
From form "C" I succeed to read the value of "VarB" with the instruction:
m_varC =frm.RetVarB
if I declare "frm" like variable it only Public of the
Form "B". Not creed but that this is the only possible method. To me
it does not appeal to declare like "Public" the variable one "frm"
in the form "B"

Hello and Thanks.
Nov 21 '05 #1
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2 Replies


P: n/a
Add a module to your project, call it something like "globals" which
contains your variable. If you set the variable with the "Private" keyword,
you will not be able to read that variable in ANY of your forms. But if you
set it with the "Public" keyword, it will be accessible to all your forms --
from anywhere in your application.

BUT. that goes without saying: "Don't expose what you don't have to." which
basically means, you SHOULD set your variable with the "Private" keyword,
and then add either a "ReadOnly" accessor to read the variable.

For example:
Private _MyVariable As String 'this is a private variable: note the "_"
before the variable name.
'the accessor to read the value
Public ReadOnly Property MyVariable() As String 'note the readonly keyword
Get
Return _MyVariable 'Returns the value of the variable
End Get
End Property

Now if you want to read & write to the variable:
Private _MyVariable As String 'this is a private variable: note the "_"
before the variable name.
'the accessor to read the value
Public ReadOnly Property MyVariable() As String 'note the readonly keyword
Get
Return _MyVariable 'Returns as string value
End Get
Set (ByVal Value As String)
_MyVariable = Value 'accepts a string value
End Set
End Property

By Adding a module that is separate from your forms, you can contain any
number of variables with different accessors. You are not limited to
accessors to read/write to variables, you can use Subroutines "Sub" or
Functions. Example:

Public Sub SetMyVariable(ByVal Str As String)
'set the variable
_MyVariable = Str 'note Str is the parameter that in the routine.
End Sub

Public Funtion MyVariable(ByVal Str As String)
Try
'check to see if you're setting the variable
'or wanting to read from it
Select Case Str
Case "" 'nothing is being passed to the function
Case Else 'something is being passed to the function
'handle the case here
End Select
Catch (Ex As Exception)
Console.WriteLine("Exception: " & Ex.toString())
Exit Function
End Try
End Function

These are just a few examples of how you can deal with variables over
multiple forms. There are other, more efficient ways, but you'll discover
those on your own.

--
Message posted via http://www.dotnetmonster.com
Nov 21 '05 #2

P: n/a
One other thing: Regarding WinForms -- they are objects just like
everything in .NET so they should be treated as such. If you've got
variables that are contained in one form and you want to read them in
another form, you'll run into a hell of a lot of headaches, expecially if
you're destroying the form (object) after you close it -- which is what you
SHOULD do -- that is the reason you want to make sure variables that are
shared throught your application are centralized in a spot that can be
easily accessed by ANY form.

--
Message posted via http://www.dotnetmonster.com
Nov 21 '05 #3

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