I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
..
..
..
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
..
..
..
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler complains
Is there a good way to do this?
Thanks
13  1492 
Just Me, I have two forms. Each contains a property, say Prop.
Is there a good way to do this?
Polymorphism, one of the tenants of OO, is a good way to do this. You can
use either Class Inheritance or Interface Implementation to achieve this
Polymorphism.
' Class Inheritance
Public Class BaseForm
Inherits System.Windows.Forms.Form
Public Property Prop As Integer
...
End Class
Public Class Form1
Inherits BaseForm
...
End Class
Public Class Form2
Inherits BaseForm
...
End Class
Public FormBeingUsed as BaseForm
FormBeingUsed= Form1
FormBeingUsed.Prop=123
FormBeingUsed=Form2
FormBeingUsed.Prop=123
' Interface Implementation
Public Interface IProp
Public Property Prop As Integer
...
End Interface
Public Class Form1
Inherits System.Windows.Forms.Form
Implements IProp
Public Property Prop As Integer Implements IProp.Prop
...
End Class
Public Class Form2
Inherits System.Windows.Forms.Form
Implements IProp
Public Property Prop As Integer Implements IProp.Prop
...
End Class
Public FormBeingUsed as IProp
FormBeingUsed= Form1
FormBeingUsed.Prop=123
FormBeingUsed=Form2
FormBeingUsed.Prop=123
You could define Prop to be Overridable in BaseForm or define an
OnPropChanged method that the BaseForm.Prop.Set method calls when the value
changes if you need derived forms to know about the value of Prop
changing...
I would favor Class Inheritance over Interface Implementation as normally
Class Inheritance will produce less code.
Hope this helps
Jay
" Just Me" <gr****@a-znet.com> wrote in message
news:u1**************@TK2MSFTNGP09.phx.gbl...I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
" Just Me" <gr****@a-znet.com> schrieb: I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
\\\
Public Interface IUsable
Property Used As Boolean
End Interface
Public Class Form1
Inherits Form
Implements IUsable
Public Property Used() As Boolean Implements IUsable.Used
...
End Property
...
End Class
Public Class Form2
...
End Class
..
..
..
Dim f As IUsable
If...Then
f = New Form1()
Else
f = New Form2()
End If
f.Used = True
///
Another approach would use a common base class that adds a 'Used' property
to the form class and from which 'Form1' and 'Form2' inherit.
--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>
Just Me, I have two forms. Each contains a property, say Prop.
Is there a good way to do this?
Polymorphism, one of the tenants of OO, is a good way to do this. You can
use either Class Inheritance or Interface Implementation to achieve this
Polymorphism.
' Class Inheritance
Public Class BaseForm
Inherits System.Windows.Forms.Form
Public Property Prop As Integer
...
End Class
Public Class Form1
Inherits BaseForm
...
End Class
Public Class Form2
Inherits BaseForm
...
End Class
Public FormBeingUsed as BaseForm
FormBeingUsed= Form1
FormBeingUsed.Prop=123
FormBeingUsed=Form2
FormBeingUsed.Prop=123
' Interface Implementation
Public Interface IProp
Public Property Prop As Integer
...
End Interface
Public Class Form1
Inherits System.Windows.Forms.Form
Implements IProp
Public Property Prop As Integer Implements IProp.Prop
...
End Class
Public Class Form2
Inherits System.Windows.Forms.Form
Implements IProp
Public Property Prop As Integer Implements IProp.Prop
...
End Class
Public FormBeingUsed as IProp
FormBeingUsed= Form1
FormBeingUsed.Prop=123
FormBeingUsed=Form2
FormBeingUsed.Prop=123
You could define Prop to be Overridable in BaseForm or define an
OnPropChanged method that the BaseForm.Prop.Set method calls when the value
changes if you need derived forms to know about the value of Prop
changing...
I would favor Class Inheritance over Interface Implementation as normally
Class Inheritance will produce less code.
Hope this helps
Jay
" Just Me" <gr****@a-znet.com> wrote in message
news:u1**************@TK2MSFTNGP09.phx.gbl...I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
Every once in a while I ask a question that results in especially
interesting answers.
Answers that not only solve but have some academically interesting value.
I think these answers both helped and stimulated.
Thanks
" Just Me" <gr****@a-znet.com> wrote in message
news:u1**************@TK2MSFTNGP09.phx.gbl... I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
Every once in a while I ask a question that results in especially
interesting answers.
Answers that not only solve but have some academically interesting value.
I think these answers both helped and stimulated.
Thanks
" Just Me" <gr****@a-znet.com> wrote in message
news:u1**************@TK2MSFTNGP09.phx.gbl... I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
What's going on below. It looks like late binding is used for sender.Index
since Object does not have an index property.
Private Sub HandleTool_Click(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim Index As Integer = sender.Index
If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Thanks again
" Just Me" gr****@a-znet.com> wrote in message I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
What's going on below. It looks like late binding is used for sender.Index
since Object does not have an index property.
Private Sub HandleTool_Click(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim Index As Integer = sender.Index
If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Thanks again
" Just Me" gr****@a-znet.com> wrote in message I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
Just Me,
It looks like late binding to me. Do you have Option Strict On at the top of
the source file?
I use Option Strict On at the top of every source file as I prefer compile
time errors over hard to track down run time errors.
Where I need to use late binding (such as COM interop with CDO), I isolate
the late binding to a small isolated module in the far corner of my app... If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Declaring a variable as Object does not enable late binding, you need to use
Option Strict Off to enable late binding, when you use late binding you run
the risk (a potentially high risk) have having hard to track down run time
errors, instead of obvious compile time errors. Not to mention that late
binding is generally a couple of magnitudes slower then early binding...
Unfortunately Option Strict Off is the default under project properties. I
normally include Option Strict On (or Off) in each source file, so its
obvious to other developers (who may link to the file) that the file does or
does not intend on using late binding...
Hope this helps
Jay
" Just Me" <gr****@a-znet.com> wrote in message
news:uv**************@tk2msftngp13.phx.gbl... What's going on below. It looks like late binding is used for sender.Index
since Object does not have an index property.
Private Sub HandleTool_Click(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim Index As Integer = sender.Index
If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Thanks again
" Just Me" gr****@a-znet.com> wrote in messageI have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
Just Me,
It looks like late binding to me. Do you have Option Strict On at the top of
the source file?
I use Option Strict On at the top of every source file as I prefer compile
time errors over hard to track down run time errors.
Where I need to use late binding (such as COM interop with CDO), I isolate
the late binding to a small isolated module in the far corner of my app... If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Declaring a variable as Object does not enable late binding, you need to use
Option Strict Off to enable late binding, when you use late binding you run
the risk (a potentially high risk) have having hard to track down run time
errors, instead of obvious compile time errors. Not to mention that late
binding is generally a couple of magnitudes slower then early binding...
Unfortunately Option Strict Off is the default under project properties. I
normally include Option Strict On (or Off) in each source file, so its
obvious to other developers (who may link to the file) that the file does or
does not intend on using late binding...
Hope this helps
Jay
" Just Me" <gr****@a-znet.com> wrote in message
news:uv**************@tk2msftngp13.phx.gbl... What's going on below. It looks like late binding is used for sender.Index
since Object does not have an index property.
Private Sub HandleTool_Click(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim Index As Integer = sender.Index
If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Thanks again
" Just Me" gr****@a-znet.com> wrote in messageI have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
I do have Option Strict Off.
I didn't know late binding was possible.
Thanks for the info
"Jay B. Harlow [MVP - Outlook]" <Ja************@msn.com> wrote in message
news:OD**************@tk2msftngp13.phx.gbl... Just Me,
It looks like late binding to me. Do you have Option Strict On at the top
of the source file?
I use Option Strict On at the top of every source file as I prefer compile
time errors over hard to track down run time errors.
Where I need to use late binding (such as COM interop with CDO), I isolate
the late binding to a small isolated module in the far corner of my app...
If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Declaring a variable as Object does not enable late binding, you need to
use Option Strict Off to enable late binding, when you use late binding
you run the risk (a potentially high risk) have having hard to track down
run time errors, instead of obvious compile time errors. Not to mention
that late binding is generally a couple of magnitudes slower then early
binding...
Unfortunately Option Strict Off is the default under project properties. I
normally include Option Strict On (or Off) in each source file, so its
obvious to other developers (who may link to the file) that the file does
or does not intend on using late binding...
Hope this helps
Jay
" Just Me" <gr****@a-znet.com> wrote in message
news:uv**************@tk2msftngp13.phx.gbl... What's going on below. It looks like late binding is used for
sender.Index since Object does not have an index property.
Private Sub HandleTool_Click(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim Index As Integer = sender.Index
If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Thanks again
" Just Me" gr****@a-znet.com> wrote in messageI have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
Just Me,
Late binding is possible, but it is not recommended.
I only use it in very select cases, which normally involves COM interop to
COM objects that are intended for VBScript (all parameters & properties are
type Object). Even then I try to isolate the late binding or encapsulate it
in classes where I have a heavy dose of DirectCasts (casting the property or
return value to its actual type).
Remember that late binding is inherently slower (as the method or property)
needs to be looked up at runtime rather compile time. These look ups can
fail, or an unexpected implicit conversion may occur which can create hard
to track down run time errors...
So in your case I strongly recommend using what Herfried & I initially
suggested!
Hope this helps
Jay
" Just Me" <gr****@a-znet.com> wrote in message
news:%2****************@TK2MSFTNGP14.phx.gbl... I do have Option Strict Off.
I didn't know late binding was possible.
Thanks for the info
"Jay B. Harlow [MVP - Outlook]" <Ja************@msn.com> wrote in message
news:OD**************@tk2msftngp13.phx.gbl... Just Me,
It looks like late binding to me. Do you have Option Strict On at the top
of the source file?
I use Option Strict On at the top of every source file as I prefer
compile time errors over hard to track down run time errors.
Where I need to use late binding (such as COM interop with CDO), I
isolate the late binding to a small isolated module in the far corner of
my app...
If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Declaring a variable as Object does not enable late binding, you need to
use Option Strict Off to enable late binding, when you use late binding
you run the risk (a potentially high risk) have having hard to track down
run time errors, instead of obvious compile time errors. Not to mention
that late binding is generally a couple of magnitudes slower then early
binding...
Unfortunately Option Strict Off is the default under project properties.
I normally include Option Strict On (or Off) in each source file, so its
obvious to other developers (who may link to the file) that the file does
or does not intend on using late binding...
Hope this helps
Jay
" Just Me" <gr****@a-znet.com> wrote in message
news:uv**************@tk2msftngp13.phx.gbl... What's going on below. It looks like late binding is used for
sender.Index since Object does not have an index property.
Private Sub HandleTool_Click(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim Index As Integer = sender.Index
If so, why isn't that a solution to the problem I posted below?
That is, using: Public FormBeingUsed as Object
Thanks again
" Just Me" gr****@a-znet.com> wrote in message
I have two forms. Each contains a property, say Prop.
I do
Public FormBeingUsed as Form
.
.
.
Then I do
FormBeingUsed= Form1
or maybe
FormBeingUsed=Form2
.
.
.
then I want to do
FormBeingUsed.Prop=123
Of course, because Form does not have a property Prop the compiler
complains
Is there a good way to do this?
Thanks
Just Me,
I miss something in the answers
FormBeingUsed= new Form2
if typeof formbeingused Is Form2 then
Directcast(FormBeingUsed,Form2).Prop=123
end if
When this was already told, than sorry
I hope this helps anyway something?
Cor
I already received good answers.
Thanks anyway!
"Cor Ligthert" <no************@planet.nl> wrote in message
news:uM**************@tk2msftngp13.phx.gbl... Just Me,
I miss something in the answers
FormBeingUsed= new Form2
if typeof formbeingused Is Form2 then
Directcast(FormBeingUsed,Form2).Prop=123
end if
When this was already told, than sorry
I hope this helps anyway something?
Cor
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