Passing a form object in a function

[Sebastian Santacroce]

Hi,
If I want to pass a form (forms I have created) to a
function what would I set the declaration as

for example

Dim p as existingForm
OpenForm (p, existingForm)
Function (P as windows.forms.f orm, thisForm as *******)
p=NEW thisForm
.....

What do I put in *******?

[William Ryan eMVP]

as ExistingForm. If I'm reading this right, you don't even need to pass the
P.
"Sebastian Santacroce" <se******@ilogi c.com> wrote in message
news:82******** *************** *****@phx.gbl.. .

Hi,
If I want to pass a form (forms I have created) to a
function what would I set the declaration as

for example

Dim p as existingForm
OpenForm (p, existingForm)
Function (P as windows.forms.f orm, thisForm as *******)
p=NEW thisForm
....

What do I put in *******?

[solex]

Dim p as existingForm

OpenForm(p)

Function(ByRef theForm as existingForm)
End Function
"Sebastian Santacroce" <se******@ilogi c.com> wrote in message
news:82******** *************** *****@phx.gbl.. .

Hi,
If I want to pass a form (forms I have created) to a
function what would I set the declaration as

for example

Dim p as existingForm
OpenForm (p, existingForm)
Function (P as windows.forms.f orm, thisForm as *******)
p=NEW thisForm
....

What do I put in *******?

[Sven Groot]

Sebastian Santacroce wrote:

Hi,
If I want to pass a form (forms I have created) to a
function what would I set the declaration as

for example

Dim p as existingForm
OpenForm (p, existingForm)
Function (P as windows.forms.f orm, thisForm as *******)
p=NEW thisForm
....

What do I put in *******?

If I read this right, you want to have a function that create an instance of
a type, without knowing a priori exactly what that type will be. Because
..Net doesn't have generics (yet), the only way to do this is using
reflection. Note that the example below will be slower than just using 'p =
new existingForm'.

First, I'd think the design of your program through to decide if you
*really* need this. But if you must do it, this is how:

Imports System.Reflecti on

Public Sub OpenForm(ByVal p As Windows.Forms.F orm, ByVal thisForm As Type)
Dim ci As ConstructorInfo = thisForm.GetCon structor(Type.E mptyTypes)
p = ci.Invoke(Nothi ng)
' do something with p.
End Sub

Dim p As existingForm
OpenForm(p, Type.GetType("Y ourNamespace.ex istingForm"))

Again, only do this if you have absolutely no alternative. It is ugly code,
hell to maintain, not very performant, and not type-safe.

--
Sven Groot

http://unforgiven.bloghorn.com

[Herfried K. Wagner [MVP]]

* "Sebastian Santacroce" <se******@ilogi c.com> scripsit:

If I want to pass a form (forms I have created) to a
function what would I set the declaration as

for example

Dim p as existingForm
OpenForm (p, existingForm)
Function (P as windows.forms.f orm, thisForm as *******)
p=NEW thisForm
....

What do I put in *******?

I am not sure what you want to do, but maybe you are looking for this:

\\\
Private Function CreateClassByNa me( _
ByVal PartialAssembly Name As String, _
ByVal QualifiedClassN ame As String _
) As Object
Return _
Activator.Creat eInstance( _
[Assembly].LoadWithPartia lName( _
PartialAssembly Name _
).GetType(Quali fiedClassName) _
)
End Function
///

Usage:

\\\
Dim c As Control = _
DirectCast( _
CreateClassByNa me( _
"System.Windows .Forms", _
"System.Windows .Forms.Button" _
), _
Control _
)
With c
.Location = New Point(10, 10)
.Size = New Size(80, 26)
.Text = "Hello World"
End With
Me.Controls.Add (c)
///

--
Herfried K. Wagner [MVP]
<URL:http://dotnet.mvps.org/>

[Sebastian Santacroce]

This is exactly what I was looking for but its not
working.
The
Type.GetType("Y ourNamespace.ex istingForm")

is returning "Nothing".
What would I put under "YourNamespace" ?
would one always exist.
This solution has only one project and I haven't created
any namespaces but the form is in a solution folder.
Is there something I'm missing?

Thanks.

-----Original Message-----
Sebastian Santacroce wrote:

Hi,
If I want to pass a form (forms I have created) to a
function what would I set the declaration as

for example

Dim p as existingForm
OpenForm (p, existingForm)
Function (P as windows.forms.f orm, thisForm as *******)
p=NEW thisForm
....

What do I put in *******?
If I read this right, you want to have a function that

create an instance ofa type, without knowing a priori exactly what that type will be. Because..Net doesn't have generics (yet), the only way to do this is usingreflection. Note that the example below will be slower than just using 'p =new existingForm'.

First, I'd think the design of your program through to decide if you*really* need this. But if you must do it, this is how:

Imports System.Reflecti on

Public Sub OpenForm(ByVal p As Windows.Forms.F orm, ByVal thisForm As Type) Dim ci As ConstructorInfo = thisForm.GetCon structor (Type.EmptyType s) p = ci.Invoke(Nothi ng)
' do something with p.
End Sub

Dim p As existingForm
OpenForm(p, Type.GetType("Y ourNamespace.ex istingForm"))

Again, only do this if you have absolutely no alternative. It is ugly code,hell to maintain, not very performant, and not type-safe.

--
Sven Groot

http://unforgiven.bloghorn.com

.

[Armin Zingler]

"Sebastian Santacroce" <se*******@ilog ic.com> schrieb

This is exactly what I was looking for but its not
working.
The
Type.GetType("Y ourNamespace.ex istingForm")

is returning "Nothing".
What would I put under "YourNamespace" ?
would one always exist.
This solution has only one project and I haven't created
any namespaces but the form is in a solution folder.
Is there something I'm missing?

Open the class view or the object browser.
--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

[Sven Groot]

Sebastian Santacroce wrote:

This is exactly what I was looking for but its not
working.
The
Type.GetType("Y ourNamespace.ex istingForm")

is returning "Nothing".
What would I put under "YourNamespace" ?
would one always exist.

The default root namespace for a VB.NET project is always the project name,
unless specified otherwise in the project properties.

--
Sven Groot

http://unforgiven.bloghorn.com

[Sven Groot]

Sven Groot wrote:

Public Sub OpenForm(ByVal p As Windows.Forms.F orm, ByVal thisForm As
Type)

Upon re-reading, it occurred to me you probably want the form instance to be
accessible through the passed first parameter once OpenForm has returned. In
which case you should put:
Public Sub OpenForm(ByRef p As Windows.Forms.F orm, ByVal thisForm As Type)

Note the ByRef instead of ByVal for the first parameter.

--
Sven Groot

http://unforgiven.bloghorn.com

[Sebastian]

So that worked great now.
I need to check if the form has been closed ie, the
variable has been disposed so I can recreate the form.

How would I check if the variable is disposed?

-----Original Message-----
Sebastian Santacroce wrote:

This is exactly what I was looking for but its not
working.
The
Type.GetType("Y ourNamespace.ex istingForm")

is returning "Nothing".
What would I put under "YourNamespace" ?
would one always exist.
The default root namespace for a VB.NET project is always

the project name,unless specified otherwise in the project properties.

--
Sven Groot

http://unforgiven.bloghorn.com

.