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Creating an object dynamically using Reflection and running in a seperate thread

I would normally use code such as :

Dim Customer as new Customer
Dim t as new threading.threa d(AddressOf Customer.Displa yCustomer)
Customer.Custom erId=MyCustomer Id
t.start

Which would create a new thread to display a customer on the screen for example.

However, I have a problem with circular references in my objects which means that I have to load the customer object using reflection ie :

Dim Customer As Object

Dim dmsobj As New DmsObjects.Func tions

Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing) <--- this is a wrapper round some reflection code to load up the object

Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)

customer.displa ycustomer

This code works.

However, I want to do :

Dim Customer As Object

Dim dmsobj As New DmsObjects.Func tions

Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing)

Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)

Dim t As New Threading.Threa d(AddressOf Customer.Displa yCustomer)

t.Start()

This doesn't compile, due to latebinding, it complains that "Customer.Displ ayCustomer" is not a valid method.

How can I acheive this??

Many thanks in advance.

Simon

Nov 20 '05 #1
6 1926
Activator.Creat eInstance
"Simon Verona" <ne**@aphrodite uk.com> wrote in message news:uQ******** ******@TK2MSFTN GP09.phx.gbl...
I would normally use code such as :

Dim Customer as new Customer
Dim t as new threading.threa d(AddressOf Customer.Displa yCustomer)
Customer.Custom erId=MyCustomer Id
t.start

Which would create a new thread to display a customer on the screen for example.

However, I have a problem with circular references in my objects which means that I have to load the customer object using reflection ie :

Dim Customer As Object

Dim dmsobj As New DmsObjects.Func tions

Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing) <--- this is a wrapper round some reflection code to load up the object

Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)

customer.displa ycustomer

This code works.

However, I want to do :

Dim Customer As Object

Dim dmsobj As New DmsObjects.Func tions

Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing)

Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)

Dim t As New Threading.Threa d(AddressOf Customer.Displa yCustomer)

t.Start()

This doesn't compile, due to latebinding, it complains that "Customer.Displ ayCustomer" is not a valid method.

How can I acheive this??

Many thanks in advance.

Simon

Nov 20 '05 #2
Thanks for the pointer.. Unfortunately, I can't quite work out the syntax for using this.

Is it possible to put together an example of use ? Perhaps using my code as the example????

Thanks in advance.

Simon
"CJ Taylor" <no****@blowgoa ts.com> wrote in message news:vs******** ****@corp.super news.com...
Activator.Creat eInstance
"Simon Verona" <ne**@aphrodite uk.com> wrote in message news:uQ******** ******@TK2MSFTN GP09.phx.gbl...
I would normally use code such as :

Dim Customer as new Customer
Dim t as new threading.threa d(AddressOf Customer.Displa yCustomer)
Customer.Custom erId=MyCustomer Id
t.start

Which would create a new thread to display a customer on the screen for example.

However, I have a problem with circular references in my objects which means that I have to load the customer object using reflection ie :

Dim Customer As Object

Dim dmsobj As New DmsObjects.Func tions

Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing) <--- this is a wrapper round some reflection code to load up the object

Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)

customer.displa ycustomer

This code works.

However, I want to do :

Dim Customer As Object

Dim dmsobj As New DmsObjects.Func tions

Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing)

Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)

Dim t As New Threading.Threa d(AddressOf Customer.Displa yCustomer)

t.Start()

This doesn't compile, due to latebinding, it complains that "Customer.Displ ayCustomer" is not a valid method.

How can I acheive this??

Many thanks in advance.

Simon

Nov 20 '05 #3
* "Simon Verona" <ne**@aphrodite uk.com> scripsit:
Thanks for the pointer.. Unfortunately, I can't quite work out the syntax for using this.


For example (there are many other ways to use 'CreateInstance '):

\\\
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]
<http://www.mvps.org/dotnet>
Nov 20 '05 #4
I'm getting very confused.

I think the code that you've put in is the code to construct the object in the first place - I have very similar code that does this.

I can't work out how to write the code that is used when creating the thread:

ie in my code:

Dim Customer As Object
Dim dmsobj As New DmsObjects.Func tions
Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing)
Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)
Dim t As New Threading.Threa d(AddressOf Customer.Displa yCustomer)
t.Start()

I need to know what to put in place of the AddressOf Customer.Displa yCustomer when creating the thread. I'm sure that the reflection class allows you to create a delegate pointer to a specific method, but I can't work out how! It's getting very frustrating.

Out of interest, the function dmsobj.LoadMeBy Name is as follows:

Public Shared Function LoadMeByName(By Val vstrAssemblyNam e As String, ByVal vstrClassName As String, ByVal vArgs() As Object) As Object
'************** *************** *************** *************** *************** **********
'dynamically load object from assembly for late binding purpose
' *************** *************** *************** *************** *************** **********
Dim objAssembly As Reflection.Asse mbly
Dim objtemp As Object
Dim Params() As Object
'MsgBox(Applica tion.StartupPat h)
If Dir(Application .StartupPath & "\" & vstrAssemblyNam e).Equals("") Then
Err.Raise(-1, "LoadMeByNa me", "assembly could not found, wrong assembly name given ")
Exit Function
End If
objAssembly = objAssembly.Loa dFrom(Applicati on.StartupPath & "\" & vstrAssemblyNam e)
objtemp = objAssembly.Cre ateInstance(vst rClassName, True, Reflection.Bind ingFlags.Create Instance, Nothing, vArgs, Nothing, Nothing)
If objtemp Is Nothing Then
Err.Raise(-1, "LoadMeByNa me", "assembly could not found, wrong assembly name given ")
Exit Function
End If
' LoadMeByName = objtemp
Return objtemp
End Function

Hopefully, somebody will take pity on me on a Friday!!

Many thanks in advance,
Simon
"Herfried K. Wagner [MVP]" <hi************ ***@gmx.at> wrote in message news:bq******** *****@ID-208219.news.uni-berlin.de...
* "Simon Verona" <ne**@aphrodite uk.com> scripsit:
Thanks for the pointer.. Unfortunately, I can't quite work out the syntax for using this.


For example (there are many other ways to use 'CreateInstance '):

\\\
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]
<http://www.mvps.org/dotnet>

Nov 20 '05 #5
Ahh

You can create a delegate, however, I wouldn't free thread it using AddressOf.

What does your threading code look like? Do you have it yet?

i.e.

Dim myThread as new System.Threadin g.Thread(Addres sOf myFunctionCall)

Now, you can't pass parameters to Threading start calls...

So,if your myFunctionCall is in another class, you have to instantiate it and set the proper "parameter" values... i.e using properties and then the myFunctionCall (which actually starts the execution on a new thread)

such that

Dim myObject as New myObject

myObject.Parame ter1 = [a paramter]
myObject.Parame ter2 = [another parameter]

Dim myThread as System.Threadin g.Thread

myThread = new System.Threadin g.Thread (AddressOf myObject.MyThre adStarterFuncti on)

myThread.Start( )

' do some stuff - new thread executes its stuff, you do whatever else you want... Join
'just shuts the thread down (read about thread states).

myThread.join()
"Simon Verona" <ne**@aphrodite uk.com> wrote in message news:ux******** ******@tk2msftn gp13.phx.gbl...
I'm getting very confused.

I think the code that you've put in is the code to construct the object in the first place - I have very similar code that does this.

I can't work out how to write the code that is used when creating the thread:

ie in my code:

Dim Customer As Object
Dim dmsobj As New DmsObjects.Func tions
Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing)
Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)
Dim t As New Threading.Threa d(AddressOf Customer.Displa yCustomer)
t.Start()

I need to know what to put in place of the AddressOf Customer.Displa yCustomer when creating the thread. I'm sure that the reflection class allows you to create a delegate pointer to a specific method, but I can't work out how! It's getting very frustrating.

Out of interest, the function dmsobj.LoadMeBy Name is as follows:

Public Shared Function LoadMeByName(By Val vstrAssemblyNam e As String, ByVal vstrClassName As String, ByVal vArgs() As Object) As Object
'************** *************** *************** *************** *************** **********
'dynamically load object from assembly for late binding purpose
' *************** *************** *************** *************** *************** **********
Dim objAssembly As Reflection.Asse mbly
Dim objtemp As Object
Dim Params() As Object
'MsgBox(Applica tion.StartupPat h)
If Dir(Application .StartupPath & "\" & vstrAssemblyNam e).Equals("") Then
Err.Raise(-1, "LoadMeByNa me", "assembly could not found, wrong assembly name given ")
Exit Function
End If
objAssembly = objAssembly.Loa dFrom(Applicati on.StartupPath & "\" & vstrAssemblyNam e)
objtemp = objAssembly.Cre ateInstance(vst rClassName, True, Reflection.Bind ingFlags.Create Instance, Nothing, vArgs, Nothing, Nothing)
If objtemp Is Nothing Then
Err.Raise(-1, "LoadMeByNa me", "assembly could not found, wrong assembly name given ")
Exit Function
End If
' LoadMeByName = objtemp
Return objtemp
End Function

Hopefully, somebody will take pity on me on a Friday!!

Many thanks in advance,
Simon
"Herfried K. Wagner [MVP]" <hi************ ***@gmx.at> wrote in message news:bq******** *****@ID-208219.news.uni-berlin.de...
* "Simon Verona" <ne**@aphrodite uk.com> scripsit:
Thanks for the pointer.. Unfortunately, I can't quite work out the syntax for using this.


For example (there are many other ways to use 'CreateInstance '):

\\\
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]
<http://www.mvps.org/dotnet>

Nov 20 '05 #6
Ahhh

my bad... sorry had to re read it again...

help://MS.VSCC.2003/MS.MSDNQTR.2003 FEB.1033

has instructions on how to create a delegate... I hope this helps.
"Simon Verona" <ne**@aphrodite uk.com> wrote in message news:ux******** ******@tk2msftn gp13.phx.gbl...
I'm getting very confused.

I think the code that you've put in is the code to construct the object in the first place - I have very similar code that does this.

I can't work out how to write the code that is used when creating the thread:

ie in my code:

Dim Customer As Object
Dim dmsobj As New DmsObjects.Func tions
Customer = dmsobj.LoadMeBy Name("DMSCustom er.dll", "DMSCustomer.Cu stomer", Nothing)
Customer.Custom er = dms.data("Activ ityLog", 5, RowNo)
Dim t As New Threading.Threa d(AddressOf Customer.Displa yCustomer)
t.Start()

I need to know what to put in place of the AddressOf Customer.Displa yCustomer when creating the thread. I'm sure that the reflection class allows you to create a delegate pointer to a specific method, but I can't work out how! It's getting very frustrating.

Out of interest, the function dmsobj.LoadMeBy Name is as follows:

Public Shared Function LoadMeByName(By Val vstrAssemblyNam e As String, ByVal vstrClassName As String, ByVal vArgs() As Object) As Object
'************** *************** *************** *************** *************** **********
'dynamically load object from assembly for late binding purpose
' *************** *************** *************** *************** *************** **********
Dim objAssembly As Reflection.Asse mbly
Dim objtemp As Object
Dim Params() As Object
'MsgBox(Applica tion.StartupPat h)
If Dir(Application .StartupPath & "\" & vstrAssemblyNam e).Equals("") Then
Err.Raise(-1, "LoadMeByNa me", "assembly could not found, wrong assembly name given ")
Exit Function
End If
objAssembly = objAssembly.Loa dFrom(Applicati on.StartupPath & "\" & vstrAssemblyNam e)
objtemp = objAssembly.Cre ateInstance(vst rClassName, True, Reflection.Bind ingFlags.Create Instance, Nothing, vArgs, Nothing, Nothing)
If objtemp Is Nothing Then
Err.Raise(-1, "LoadMeByNa me", "assembly could not found, wrong assembly name given ")
Exit Function
End If
' LoadMeByName = objtemp
Return objtemp
End Function

Hopefully, somebody will take pity on me on a Friday!!

Many thanks in advance,
Simon
"Herfried K. Wagner [MVP]" <hi************ ***@gmx.at> wrote in message news:bq******** *****@ID-208219.news.uni-berlin.de...
* "Simon Verona" <ne**@aphrodite uk.com> scripsit:
Thanks for the pointer.. Unfortunately, I can't quite work out the syntax for using this.


For example (there are many other ways to use 'CreateInstance '):

\\\
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]
<http://www.mvps.org/dotnet>

Nov 20 '05 #7

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