I would like to check if a property's type is an interface (not a specific interface, but any interface).
dim __PropertyInfo As PropertyInfo
dim b as boolean = isinterface(__PropertyInfo)
[code].....
I'm currently trying to create a class that is a composition of the SqlDataAdapter class (as unfortunately you can't inherit from it). In order to try and make it as similar as possible I'm using all the same inherits and interfaces as is documented on MSDN.The problem that I am having is that there are some properties where the interface specifies that the type of the property is IDbCommand. But in the SqlDataAdapter the property type is SqlCommand.
View 3 RepliesI am trying to implement the Strategy design pattern using interfaces.However, while developing some code I stumbled upon something strange.The type of the object is not verified in design-time.Observe the following code.Notice that Foo implements IFoo and Bar DOES NOT implement this interface.No error is shown when trying this:[code]This code compiles fine. No error is shown in Visual Studio.However, when I run this piece of code, I receive an InvalidCastException.The output of the console:[code]
View 1 RepliesI'm having some very weird issues with interfaces right now.
I have a very simple setup. In one of my class, I have a Property implementing a Property from an Interface.
In my class it's like:
Private _oForm As IForm
Public Property Form As IForm Implements IContainer.Form
Set(value As IForm)
[Code]...
I have like dozens of interfaces like this working throughout my project and I can't believe this simple one can't work!
Is there a way for implementers of an interface where a ReadOnly property is defined to make it a complete Read/Write Property ?
Imagine I define an interface to provide a ReadOnly Property (i.e., just a getter for a given value) :
Interface SomeInterface
'the interface only say that implementers must provide a value for reading
ReadOnly Property PublicProperty As String
End Interface
This means implementers must commit to providing a value. But I would like a given implementer to also allow setting that value. In my head, this would mean providing the Property's setter as part of the implementation, doing something like this :
Public Property PublicProperty As String Implements SomeInterface.PublicProperty
Get
Return _myProperty
[code]....
I want to declare a property as an interface collection of an interface, and I want to instanciate the explicit type later, in the constructor. Something like this.
Public Class LicenseFile
Implements ILicenseFile
Public Property Collection As IList(Of ILicenseFileDataNode)
[Code]....
In short, the question is "Why It Didn't work"? This is a simplified scenario, but It's easy to take a workarround, But I need understand the reason because It's fails.
I use check boxes and place them on my user interface (See attachment)I have coded the code for "select all" button :
Code:
Private Sub checkedall_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles checkedall.Click
Dim chkboxes, outs As New Collection()
[code]....
I could not seems to check all the boxes. Is there something wrong with it? I am not sure how to assign array to check boxes.
I am building a software which will be used to create a remote desktop connection. However I'm getting this error:
Unable to cast COM object of type 'System.__ComObject' to interface type 'MSTSCLib.IMsTscNonScriptable'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{C1E6743A-41C1-4A74-832A-0DD06C1C7A0E}' failed
due to the following error: Δεν υποστηρίζεται τέτοια διασύνδεση (Exception from HRESULT: 0x80004002 E_NOINTERFACE)).
[Code]...
In trying to add a bit of usage variety to a generic class I'm working on, I ran into this issue with trying to cast an object into an interface instance where the interface is defined inside the generic class.
[Code]...
I have been trying to use vb2008 to automatically update CustomDocumentProperties fields that I have set up within a pro-forma document. I can load the Word application and word document without problems.I want to update the CustomDocumentProperties fields with data read from a dB. To do this I am assuming that I need to iterate through the CustomDocumentProperties fields within the word document and when one is "found" that matches the data I wish to merge then assign the dB value to the field.The problem is that I am getting an exception error when I try to reference the document customdocumentproperties
"Error : Unable to cast the COM object of type 'System._ComObject' to interface type 'Microsoft.Office.Interop.Word.CustomProperties'. ...... "
my code looks like;
Dim WordApp As Word._Application
Dim odoc As Word._Document
Dim BContinue As Boolean = True
[code].....
I have a number of controls (Device1, Device2, etc.) that all inherit from BaseDeviceControl. In the DragEnter event handler I am trying to test for the correct type by using the BaseDevvceControl like this....
[Code]....
I have a requirement where I need to have a "type safe" way of accessing property names, without actually instantiating an object to get to the property. To give an example, consider a method that takes as arguments a list of IMyObject and a string that represents a property name (a property that exists in IMyObject).
The methods implementation will take the list and access all the objects in the list using the property name passed... for some reason or another, we won't dwell on that!!
Now, I know that you can do this using an instantiated object, something like ...
Dim x as MyObject = nothing
Dim prop As PropertyInfo = PropHelper.GetProperty(Of MyObject)(Function() x.MyProperty)
Where my helper method uses reflection to get the name of the property as a string - there are numerous examples of this flying around on the web!
But I don't want to have to create this pointless object, I just want to do something like MyObject.MyProperty! Reflection allows you to iterate through a types properties and methods without declaring an object of that type... but I want to access a specific property and retrieve the string version of its name without iteration and without declaring an object of that type!
The main point here is that although I am trying to get the property name as a string... this is done at run time... at compile time, I want this to be type safe so if someone changes the property name, the compilation will break.
I have a number of pages which implement the same interface:[code]The function doSomethingToTextBox takes a textBox item as a parameter and performs some action on it.I know the textBox is contained on every page which implements my interface, and that it has the same name on each page.My question is: how can I declare the textBox as an interface property? This will remove the need to pass the textBox as a parameter to doSomethingToTextBox()I must also add that I'm currently accessing the TextBox using get/set methods defined as part of the interface - I don't want to have to implement these methods for each page as they are exactly the same on each page.
View 1 RepliesI have an Interface defined like this:
Public Interface ISegment
''' <value>
''' The offset where the span begins
'''</value>
[code]....
The problem is that when I try to use the interface in another class, it tells me that Offset and Length are not members of ISegment. Clearly they are. Here is the code that uses the interface
Public Sub UpdateSegmentListOnDocumentChange(Of ISegment)(ByVal list As List(Of ISegment), ByVal e As DocumentEventArgs) Implements IDocument.UpdateSegmentListOnDocumentChange
[code]....
We have an interface, which can be grossly simplified as:
[Code]...
Consider the following case:
Public Interface IHasDateUpdated
Property DateUpdated As DateTime
End Interface
Public Class MyClass
[code]....
Now, assuming I was referencing an instance of MyClass as an IHasDateUpdated; how would I determine the actual name of the property that implements the interface property via reflection?For example:
Dim x As IHasDateUpdated = New MyClass()
' How do I derive "MyDateUpdated" from "x" using x.DateUpdated?
I am trying to develop a simple interface for allowing quick lists to be generated from classes. Basically, the interface needs to return an ID and a Name. However, some classes have a calculated name property which is read only, others just use a read/write name property. Basically, all I care is that it has a getter, it does not matter if the property has a setter. How can I write this interface to handle either or without throwing compile errors?
View 1 RepliesI have a vb2008 combo box with the DropDownStyle property set to DropDownList.Now, when I set the text property to something programatically nothing happens. That is, the "something" doesn't show up on the control with list collapsed. It still doesn't show even if I force an update(If DropDownStyle property is set to DropDown, setting the text property programatically works fine, even without forcing an update).
View 4 RepliesI am using JustMock to mock interfaces for unit testing, but perhaps I'm not doing it right.[code]...
I want to mock this interface and set that property so that it can be read by consumers of the interface.Beginning with[code]...
I have the following
Imports System
Imports System.Collections.Generic
Imports System.Drawing
Imports System.Linq
Imports System.Windows.Forms
[Code] .....
But I am getting this error:
Error1Class 'DemoPlugInTwo' must implement 'ReadOnly Property name() As String' for interface 'Interfaces.IPlugins'. Implementing property must have matching 'ReadOnly' or 'WriteOnly' specifiers.C:Documents and SettingsOwnerMy DocumentsVisual Studio 2008ProjectsDemoPlugInThreeDemoPlugInThreeDemoPlugInThree.vb1420DemoPlugInThree
I am getting similar errors for the other property and method. I have them set as read only.
How can i change the backcolor property of an object to an rgb value?
i do as it says in the help:
Code:
dim ink as long
ink = rgb(233,126,190)
lblInkPot.BackColor = ink
but i get the error "Value of type "Long" cannot be converted to "system.drawing.color"", but it specifically tells you in help to use "long"...
This used to work.
<AcceptVerbs(HttpVerbs.Post)> _
Function Widget(ByVal collection As FormCollection) As ActionResult
...
If ... Then
[code]....
I upgraded to ASP.NET MVC 2 Beta and ASP.NET MVC 2 Futures Assembly for Beta and now ToValueProvider() fails with this compile-time error: Interface 'System.Web.Mvc.IValueProvider' cannot be indexed because it has no default property How do I use ModelState.SetModelValue() if not with collection.ToValueProvider()?
I already have one year experienced in c++, and built many private applications.My question is simple to ask, and simple to answer I think.When I select an item in a listview, I want the full item to be selected. Now only the TEXT in the listview item is selected. I've made a picture to clearify my problem.The picture in the link below is splitted up in two pictures. It shows what I currently have, and what I want (my aim)
View 4 RepliesI 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
While learning to use LINQ in VB.NET, I came across the following:Dim x As IEnumerable = (some LINQ query)
If you can't instantiate an interface, but only a concrete implementation of it, why is this allowed? Is there some difference between doing Dim x as (Type) and Dim x as New (Type)?
I am working on a project that has several different codes. These codes all basically are used this way:
CodeKey
Description
GetList
GetSpecific
SetProperties
All of my classes implement this. I am hesitent, however, to use an interface because of one problem--the type Codes vary by type. Some are strings, some are integers, some are bytes. The only way I could see using an interface would be to make the typeCode an object in the interface and then cast whenever I needed to use it, but that seems a bit silly. Any ideas? This is in VB.NET.
I am looking to implement the ability to compare and sort classes in my model. All of the objects in my model will need some common functionality regarding to comparisons so I created an abstract BaseComparer that implements IComparer.
Public MustInherit Class BaseComparer(Of T)
Implements IComparer(Of T)
End Class
[code].....
I can tell when the user clicks on my picturebox. Can I tell which mouse button was used? Left or right?
View 1 Replieswhat is the difference between declaring a variable in this way
ByVal
List As IEnumerable as
a parametre in a function
Dim
[Code]....
I would like to have a command prompt type interface on my form. The only thing I am aware of is a textbox, but there are no facilities to have commands and output scroll without keeping the entire history in a variable. That would be an ever increasing variable, which is ridiculous. Is there an alternate way to use a textbox as a command prompt, or is there something else I can do. Another note, is the use of an array. I know I can increase an array with commands, but this is no good either, because some responses in the box need to be paragraphs in length, so even a separate array for command and output is too cumbersome.
View 6 Replies
