Test If An Object Implements An Interface?
Sep 1, 2009I have an object parameter and I need to check if the object implements a specified interface in vb.net. How to test this?
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How To Test If Object Implements Defined Interface
Jun 5, 2011I use the IsAssignableFrom-method to check if the datasource of a bindingsource-object implements an interface i defined. The check happens inside the property-setter like this:
Private WithEvents _BindingSource As BindingSource
''' <summary>
''' BindingSource containing datasource in which search is executed.
''' </summary>
''' <remarks>Datasource must implement ISearchAndFindable.</remarks>
<Description("The BindingSource to search within."), Category("Data")> _
Public Property BindingSource() As BindingSource
[Code] .....
Drag Drop If Object Implements Interface
Sep 2, 2010I have an interface, for the sake of argument called MyInterface.I Have a Control Class, lets name it "Parent" that implements MyInterface.I have another Control Class that inherits Parent, called "Child".I have a final Control Class lets call it "Container", that accepts dragging the parent onto it.[code]I want to modify this not to only accept Parent, but to accept ANYthing that implements MyInterface. I can't figure out how the heck to get it to work. Even more confusing, if I drag the child onto Container, with the code as it is above(checking to see if a Parent was dropped), GetDataPresent always returns false. I would figure it would work, since Child inherited parent.[code]But it bombs and GetDataPresent returns false whether I dragged a Parent or a Child. I'm being an idiot somewhere..
View 1 RepliesCast A List Of Object To List Of Interface That Object Implements?
May 19, 2009I am working in VB.net and have a Class, Foo, that implements an interface, IBar.I have a List of Foo's, but I need to pass a list of IBar's into a function, but I keep getting casting errors, even when I use DirectCast.My code is [code]MainWorks works, but it would be really annoying and inefficient to have to do that everywhere I want to call this function.
View 4 RepliesC# - How To See If A Type Implements An Interface
Oct 25, 2010I need to know if a Type implements an interface. [Code] because the Interface IRule itself is assignable of IRule what raises a MissingMethodExcpetion if i try to create an instance:
ruleObj = CType(Activator.CreateInstance(typeAsm, True), Rule.IRule)
UPDATE2: IsAssignableFrom in combination with IsAbstract might be the best way to check if a given type implements an interface and is not the interface itself (what throws a MissingMethodException if you try to create an instance).
If GetType(Rule.IRule).IsAssignableFrom(typeAsm) AndAlso Not typeAsm.IsAbstract Then
Tell If A Class Implements An Interface?
Dec 4, 2009I've got a web user control (.ascx) which implements a couple of interfaces I wrote; namely IXMLBoundControl and ISectionOverridingControl.I've written a mini-CMS type application that dynamically loads controls onto the page based on information in a database. When I click a button on a web page (.aspx), I want to look at all the controls on that page, and determine if there is a control which implements the ISectionOverridingControl.
I've got my loop and I'm looping through the controls; that's fine. However I'm not sure what the best way is to determine whether or not the control implements the interface. What I'm doing at the moment (and works) is to try to cast each control into the ISectionOverridingControl and catching InvalidCastException: If I don't get the catch; I consider it's worked. If the exception is thrown then it doesn't implement the interface.
It's working, however, I consider this inefficient (relying on exceptions): surely there's a better way in VB.NET (I've seen an example in C# but it didn't convert to VB) to tell whether an instance of a class implements an interface or not?
.net - Use Mono.Cecil To Determine If A Type Implements An Interface?
Jun 23, 2012I had a look through the documentation on the Wiki, but it seems a bit thin. How do I determine if a type implements a given interface using Cecil? For my particular implementation it is important that I do not actually load the type into the AppDomain.m Here's the code that I have so far:
Dim outputModule As ModuleDefinition = ModuleDefinition.ReadModule(outputFile)
For Each assemblyType As TypeDefinition In outputModule.Types
'How to determine if assemblyType implements a specific interface?
Require That A Class Is A Windows.Forms.Control And Implements An Interface?
Nov 29, 2011I'm not sure that I'm doing the right thing here..I'm writing a user control that's supposed to be (fairly) generic. It's a bit like a modified email client specifically tailored to some of the internal things we do.
The view is composed of two main pieces, a message list and a viewer. I need this viewer to be interchangeable, so if someone wants a different style of view they can simply handle an event and change a property. My original idea was to just have an INoteViewer, but since I'm adding it to my form I also need to guarantee that this object is a Windows.Forms.Control of some sort.
Should I continue along these lines and maybe raise an ArgumentException if I can't cast it to INoteViewer, or should I go a different direction and create a class that inherits from Windows.Forms.Control?
Storing An Object That Implements Multiple Interfaces And Derives From A Certain Base (.net)
Dec 7, 2010In .net, it's possible to use generics so that a function can accept arguments which support one or more interfaces and derive from a base type, even if there does not exist any single type from which all valid argument types derive. For example, one could say: Sub Foo(Of T As {IInterface1, IInterface2, SomeBaseType})(Param as T) And be allowed to pass any derivative of SomeBaseType which implements both IInterface1 and IInterface2. This will work even if SomeBaseType does not support Interface1 and Interface2, and classes which do implement those interfaces don't share any common ancestor that also implements them. This can be very convenient if one won't need to keep the parameter anywhere after the function has exited. Unfortunately, I can't figure out a way to persist the passed-in parameter in such a way that it can later be passed to a similar function, except perhaps by using Reflection. Is there any nice way of doing that?
The closest I've been able to come up with is to define an interface INest (perhaps not the best name-- thus:
Interface INest(Of Out T)
Function Nest() As T
End Interface
And for any interface that will be used in combination with others or with base-class "constraint", define a generic version as illustrated below:
Interface IFun1
' Any members of the interface go here, e.g. ...'
Sub DoFun1()
[CODE]...
A class which will support multiple interfaces should declare itself as implementing the generic ones, with itself as the type argument.
Class test123a
Inherits sampleBase
Implements IFun1(Of test123a), IFun2(Of test123a), IFun3(Of test123a)
End Class
If that is done, one can define a function argument or class variable that supports multiple constraints thusly: Dim SomeField as IFun1(Of IFun2(Of IFun3(Of sampleBase)))
And then assign to it any class derived from sampleBase, which implements those interfaces. SomeField will implement IFun1; SomeField.Nest will implement IFun2; SomeField.Nest.Nest will implement IFun3. Note that there's no requirement that IFun1, IFun2, IFun3, or sampleBase share any common derivation other than the generic interfaces inheriting from INest(Of T). Note also that, no matter how many INest-derived interfaces a class implements, it only needs to define one implementation of INest(Of T).Nest. Not exactly beautiful, but there are two nice things about it: (1) any concrete class which in fact implements the necessary interfaces can be assigned directly to a field declared as above, without a typecast; (2) while fields which chain the types in a different order are not assignment compatible, they may be typecast to each other. Is there any better way to store something in such a way that it's "known" to support multiple interfaces and derive from a certain base type? Given that one can write such code in a type-safe manner, it would seem like the .net 2.0 CLR could probably support such a thing quite nicely if compilers offered a little assistance.
Storing An Object That Implements Multiple Interfaces And Derives From A Certain Base (.net)?
Jan 24, 2012I was looking through some legacy code we have and I noticed something that struck me as particularly odd.Say we have the concrete class TestClass. TestClass implements the interface ITestClass.What sort of behavior should I expect in the following case, then? (I didn't realize this was even possible)
Dim testClass as TestClass = Nothing
Try
testClass = New ITestClass
[code].....
.NET Class Inherits A Base Class And Implements An Interface (works In C#)?
Apr 9, 2010I am trying to create a class in VB.NET which inherits a base abstract class and also implements an interface. The interface declares a string property called Description. The base class contains a string property called Description. The main class inherits the base class and implements the interface. The existence of the Description property in the base class fulfills the interface requirements. This works fine in C# but causes issues in VB.NET.
[Code]...
Interface And Graphics :: Link A Class / Object To An Interface?
Apr 21, 2010I'm trying to make a .dll that contains a lot of basic functionality that a program can use. Currently i am trying to use interfaces to make a lot of this functionallity independend of the program using it but i hit a snag. The Basic idea is that a programmer will create his own object using the interface discribed in my .DLL file. Then implements those functions as he likes. He can then instanciate a controller (found in the same DLL) and sends his custom object implementing the interface to that Controller. The controller can then be started and will take over all the work. I do not know what type of object is send to the controller and idealy i want to program it in such a fashion that i shouldn't care as long as the object send implements that interface.In code I am trying to achieve the following: (quite simplyfied)
.Dll:
Code:
Public Interface MyInterface '<----Decleration of the interfaceFunction GetData() As Integer
Function SetData(Data As Integer)
end interface
[code]....
this propperly. I know that the second i set the interface adaptor in the Controller VS comes nagging that it can not be converted to a "MyInterface" Class. Obviously i am doing something wrong. I can change the datatype that the controller expects to the "MyController" type but that would completely ruin the whole idea of flexibillity. I am hoping someone sees what i am trying to do and can point out where i made the thinking error.
Error: Option Strict On Disallows Operands Of Type Object For Operator '='. Use The 'Is' Operator To Test For Object Identity
Jan 27, 2010I am tightening up my coding with the Option Strict set to ON. It has now produced alot of errors. An example of this is:
If AllocatedDGV.Rows(i).Cells("RoomNumber").Value = RoomsAvailableDGV.Rows(j).Cells("RoomName").Value Then
It gives me the following error: Option Strict On disallows operands of type Object for operator '='. Use the 'Is' operator to test for object identity.
Option Strict On Disallows Operands Of Type Object For Operator Use The 'Is' Operator To Test For Object Identity
Apr 6, 2012I need to write an interface to get data to/from our data files.
We have a low level class that holds field values for each record read from the files.
This just holds two values, the value read from the file (DBValue) and the updated value that may need to be written back to the file (CurrentValue).
These values may be any of the standard value types (integer, date etc) or a string.
Either value (DBValue or CurrentValue) may be null if not defined.
I have written the class to manage this data which works fine while option strict is NOT on.
But we have an office policy of having option strict on all the time.
When I put option strict on, my object value comparisons fail with the error: "Option Strict On disallows operands of type Object for operator '='. Use the 'Is' operator to test for object identity."
Question, how should I change the following code to handle option strict on ...
This is all running on Visual Studio 2010
[Code]...
.net - Interface Variables (ie Dim X As Iinterface = Object?) And Also If Object Is A Form?
Mar 10, 2010I've got 3 forms that have exactly the same functions, so I decided to create an interface.
public Interface IExample
public sub Add()
Public sub Edit()
[code]....
At this point, objfrmExample is now instantiated, even though I've not done a "objfrmExpample = new [what-goes-here?] " and I'm curious as to why.I could possibly guess that because you cannot instantiate an interface variable, then vb.net automatically creates an instance. But thats just a guess. The question is , what is meant by declaring a variable of type Interface, and how does it work?
Return An Array Of Object Interface's Rather Than An Object?
Mar 4, 2009I have an interface that describes an specialized list in my application...
[Code]....
Is there a way to make an interface serializable, or am I going to have to convert each of my objects into a concrete class implementing the interface, and then return that class?
Test If Stream Object Is Open?
Jun 30, 2009Is there a way to test if a streamreader or streamwrite is open? My application is something like this[code]...
View 7 RepliesTest To See If One Object Is Similar To Another Without Testing Each Property?
Jun 9, 2011Object.Equals I can understand but has anyone got or written an Object.Similar function? I want to test every property and value of two objects to see if they are similar or not,I can understand we can have say two red Ferrari cars but they can not occupy the same space in the same universe!!However they could look similar / identical in every other aspect. I know two cars don't make one object so they are NOT equal.In a similar fashion at run time we could put two Button1 buttons on a Form but they could have separate locations. I want to test two objects that only have the PROPERTY of color or a set of other similar simple properties.How can I test to see if one object is similar to another without testing each property,[code].....
View 15 Replies[2005] What Is The Operand To Test For Object Identity
Feb 27, 2009Private Sub cbxSubject_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbxSubject.SelectedIndexChanged
Select Case cbxCategory.SelectedItem
[code]....
I get this error message:Option Strict On disallow operands of type Object for operator '='. Use the 'Is' operator to test for object identity.But I don't know how to correct this.
Casting An Object Through An Interface (.NET 3.5)?
May 14, 2010I have an object that inherits from an interface. I can create and return the following:
Dim o As IRequest
o = New Request
Return o
This works fine. Now I want to return a List(Of Requests), so I try the following:
Dim o As List(Of IRequest)
o = New List(Of Request)
Return o
The error below is being given on o = New List(Of Request)
System.Collections.Generic.List(Of MyObjects.Request)' cannot be converted to System.Collections.Generic.List(Of MyInterfaces.IRequest)'.Consider using 'System.Collections.Generic.IEnumerable(Of MyInterfaces.IRequest)'
Interfaces - Is ISomething An Interface Or An Object Or Both
Oct 13, 2011I'm working on learning VB.Net after having programmed in VB6, VBA, and VBScript for several years. I'm assuming that something that begins with the letter I is an interface. However, a lot of places I see people/documentation referring to what appears to be class objects that begin with I. I guess I'm under the impression that Interfaces are contracts that class objects can agree to.
[Code]...
C# - Naming Convention For Interface Implementator's Object?
Sep 16, 2010What is the most commonly used convention (in C# and VB) to name object, when I want to emphesize that it is an instance of class that implements some interface. Like here:
//is iDisp correct name?
protected void Dispose(IDisposable iDisp)
{
iDisp.Dispose();
Console.WriteLine("Disposed");
}
Declaring A Variable Of Type Interface And Object
Oct 19, 2010what is the difference between declaring a variable in this way
ByVal
List As IEnumerable as
a parametre in a function
Dim
[Code]....
How To Cast Interface To Object (DailySchedule Class)
Jul 1, 2010I have a base class called Schedule and three classes inherited: DailySchedule, WeeklySchedule, MontlySchedule. Now I would like to build a form in which users can modify the schedule and I have to compile different parts of it depending on whether the schedule is daily, weekly or monthly. Then I want to have back the schedule modified. Which object can I use on the form?
I thought to implement on the base class an interface iSchedule and to pass the interface to the form, but when I'm on the form constructor how can I cast the interface to the correct class? e.g. in the form constructor I will have a sched variable as iSchedule, I can see that, for example, is a DailySchedule from an interface property called Type. But how can I cast the interface to an instance of the DailySchedule class and to access to its members?
Indicate That An Entity Framework Object Is Implementing An Interface?
Feb 1, 2011I have to begin saying that I'm working with Visual Basic. The problem is that I have a Entity Framework object and I want to indicate that this object implements a interface, for example:
Public Interface ICatalog
Property created_at() As Date
Property id() As Long
End Interface
Those properties are allready in the object. In c# I've done this just by declaring a partial class of the object and indicates that implements that interface, but in basic is not working, I supouse that is because of the language sintaxis used to declare that a property is implementing some property of the interface, for example:Public Property created_at() As Date Implements ICatalog.created_at
Interface And Graphics - Random Object Movement
Sep 27, 2010This is another question about my galaga like game. I want the enemies to move to a random spot one pixel away at each tick of a timer. How would I go about doing this?
View 6 RepliesInterface In A Function Or Similar Verification For An Object?
Sep 6, 2010Lets say I have function returns an object and that object has 10 properties. for example
myStudent.ID
myStudent.Name
myStudent.Surname
[code].....
Word 10 Interface Error 'that Method Is Not Available On That Object'
Jun 28, 2011Does anybody know why I get the error 'that method is not available on that object' when I try to interface with Word 10? Our software works fine with Word 7 and previous
View 1 RepliesArgument Not Specified For Parameter 'test' Of 'Public Shared Function TestThis(test As String)'?
Sep 25, 2010I don't understand the error, Argument not specified for parameter 'test' of 'Public Shared Function TestThis(test As String)'.
Partial Public Class Form1
Shared Sub ReceiveCallback(ByVal ar As IAsyncResult)
Form1.Invoke(TestThis, New Object(){"test"}) 'error
[code].....
Call An Event On An Object That Originated In An Interface From Another Location
May 23, 2011How can I raise an event from another class which implements an interface that contains an event?
Public Interface IMyEvent
Event MyEvent()
End Interface
[Code].....
Note the comment - that code doesn't work. How can I raise an event like this, if it's contained within another class through an interface?