(Probably obvious) .NET question - creating objects dynamically

[Jethro]

Hi all,

I have a solution, which contains several projects. Each project occupies
the same namespace, and compiles to s different .NET DLL

e.g.

MyNamespace.Thi sClass is in one DLL
MyNamespace.Tha tClass is in another DLL

I wish for a .NET EXE to be able to dynamically create an instance of either
on of the classes, given the classes name as a string.

I have tried using System.Reflecti on.Assembly calls, but watching in debug,
the Load call fails.

What would the mechanism be for doing this ?

thanks in advance.

[Herfried K. Wagner [MVP]]

Re: (Probably obvious) .NET question - creating objects dynamically

* "Jethro" <Jethro_uk@hotm ail.com> scripsit:[color=blue]
> I have a solution, which contains several projects. Each project occupies
> the same namespace, and compiles to s different .NET DLL
>
> e.g.
>
> MyNamespace.Thi sClass is in one DLL
> MyNamespace.Tha tClass is in another DLL
>
> I wish for a .NET EXE to be able to dynamically create an instance of either
> on of the classes, given the classes name as a string.
>
> I have tried using System.Reflecti on.Assembly calls, but watching in debug,
> the Load call fails.[/color]

\\\
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/>

[Jay B. Harlow [MVP - Outlook]]

Re: (Probably obvious) .NET question - creating objects dynamically

Jethro,
A variation of the Activator.Creat eInstance that I normally use.

I use System.Type.Get Type to return a Type object for the concrete class I
want (determined via the app.config). The strings in the app.config should
to be in "myproject.mycl ass, myassembly" format.

I use System.Activato r.CreateInstanc e to create an instance of the concrete
class.

' VB.NET sample
Dim s As String
s = ConfigurationSe ttings.AppSetti ngs("myplugin")

Dim t As Type
t = Type.GetType(s)

Dim obj As Object
obj = Activator.Creat eInstance(t)


' Or if you want to pass parameters to the constructor
obj = Activator.Creat eInstance(t, New Object() {p1, p2})
' the above calls the constructor that has two parameters.
' there are 7 or so overloads of CreateInstance,
' if you have default constructors or other needs

Dim plugin As MyPlugInBase
plugin = DirectCast(obj, MyBaseClass)

I use this in a couple of projects, works very well.

Hope this helps
Jay




"Jethro" <Jethro_uk@hotm ail.com> wrote in message
news:cajo2b$haa $1@hercules.bti nternet.com...[color=blue]
> Hi all,
>
> I have a solution, which contains several projects. Each project occupies
> the same namespace, and compiles to s different .NET DLL
>
> e.g.
>
> MyNamespace.Thi sClass is in one DLL
> MyNamespace.Tha tClass is in another DLL
>
> I wish for a .NET EXE to be able to dynamically create an instance of[/color]
either[color=blue]
> on of the classes, given the classes name as a string.
>
> I have tried using System.Reflecti on.Assembly calls, but watching in[/color]
debug,[color=blue]
> the Load call fails.
>
> What would the mechanism be for doing this ?
>
> thanks in advance.
>
>[/color]