I'm trying to search a generic list of 'User' business objects which has a property called 'Username': If (From u In colUsers Select u.Username Where Username.Equals(strUsername)).Count > 0 ThenI keep getting:Delegate to an instance method cannot have null 'this'.
View 16 Replies
D is a dictionary whose entry values are of Type T..What I'm attempting to do is have a delegate like "Serializer" below that I can invoke on an instance of T, such as "Entry.Value" below.Please see the "return Entry..." line below for my wishful thinking.[code]
View 2 RepliesPublic Class notifierMain
Public Class Contacts
Inherits List(Of row)
Public Sub New()
[code]....
When I debug this winforms application I get curType = "notifier.notifierMain+Contacts+row" I want to the Validate function to know it is in MyContacts. How do I do this?
How to use Generic List Where method based on index if there are mutiple 'similar' values, see example below
View 3 RepliesHere's the code I have but I'm getting syntax issues:
CODE:
I'm just looking to call ReadAndPopulate method for each item in aList. I know I can do it the traditional "For each a in aList...Next" way but wanted to learn how to do it with delegates.
Is it possible to pass multiple arguments to a delegate method from a list(Of T).ForEach call?So, I'd like to pass a listbox object to the delegate routine below:
Sub test()
Dim names As New List(Of String)
names.Add("Bruce")
names.Add("Alfred")
[code]....
Use the "new" keyword to create an object instance & Check to determine if the object is null before calling the method. I'm reading text from a text file using the following [Code]
View 9 RepliesI have a class myClass. MyClass has a property myName. I have a generic list myList(of myClass). I have to check if value of myName in all myClass objects in myList is same and is equal to a string myString. I have created a method:
Private Function IsMatching(ByVal objMyClass As MyClass, ByVal strMyString As String) As Boolean
If objMyClass.MyName = strMyString Then
Return True
Else
Return False
End If
End Function
Now I want to use is TrueForAll method of Generic list. How can I use it ?
If there was No second Parameter in IsMatching method, I could have simply used
myList.TrueForAll(AddressOf IsMatching)
But since there is a parameter strMyString, I dont understand how can I use IsTrueForAll method. How can I use IsTrueForAll method in this scenario.
Code:
Public Class SendPings
Shared Sub New()
AddHandler Post.Saved, AddressOf Post_Saved[code].....
I get a error" Method 'Private Shared Sub Ping(item As BlogEngine.Core.IPublishable, itemUrl As System.Uri)' does not have a signature compatible with delegate 'Delegate Sub WaitCallback(state As Object)'.
I have been using a pretty slick generic invoke method for UI updating from background threads. I forget where I copied it from (converted it to VB.NET from C#), but here it is: Public Sub InvokeControl(Of T As Control)(ByVal Control As t, ByVal Action As Action(Of t))
[Code]....
how to find a value in the System.Collections.Generic.List.I have:
Private ids As New List(Of Byte())
ids.add(New Byte(){&HA8,&H0F})
ids.add(New Byte(){&HFF,&H03})
ids.add(New Byte(){&H10,&H00})
I would like to find for example: &H10,&H00 in that list and if there isn't the stuff I wan't to find then how do I know that?
I have a custom list that inherits Generic.List and it has a method for deselecting all of the members named DeselectAll It has looked like this for a few weeks and has worked fine.
Public Sub DeselectAll()
MyBase.ForEach(Function(p As Publipostable) p.ModeEnvoiChoisi = Nothing)
End Sub
Today, it stopped working ?!? I reverted to an earlier version using delegates and that works fine...
Public Sub DeselectAll()
MyBase.ForEach(AddressOf DeselectModeEnvoi)
End Sub
[code]....
Edit: Stopped Working meaning it no longer sets the property p.ModeEnvoiChoisi to Nothing on each item in the list. The DeselectAll method gets called, but all the items retain their previous values...
from the documentation we have this: Multicast Delegate: Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.
so am i right to say that Multicast delegate is no different from a normal delegate other than the fact that it has arguments. so System.Action is a 'normal' delegate whereas System.Action(T)(Byval obj as T) is a multicast delegate?
Consider a MyForm class that contains a shadowed implementation of Show(). It also contains a CreateForm() method, which accepts an instance of the form and calls the shadowed sub:
[Code]....
I am trying to write a generic method, to avoid code duplication, which will create or activate a Form as an MDI children, based on its type. But I have to lines in error (see comments).
[Code]...
Consider:
Public MustInherit Class Column
Public ReadOnly Property ReturnSomethingUseful() As Object
Get
'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean'
cannot override 'Public Overridable Function ParseValue(sValue As String) As Object'
because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
I wrote a serializer (to Byte Array) for dictionaries that have a string key, but an object of some sort as its value.I've never implemented a generic type in a function or used a delegate before, so I'm a bit concerned about this being significantly slower than writing a serialization function for a specific type of Dictionary (Dictionary(Of String, MyClass) for example)Should this code be significantly slower due to the use of the generic type or the delegate?
[code]...
It works, and I could loop it and compare it to a more static Dictionary serializer, but I'm more concerned about when I start using this for a lot of different String/Object dictionary combinations, and it'll take me a long time to write a bunch of static dictionary serializers (that's what I'm hoping to avoid in the first place)edit: simplified intro text
Scroll to the bottom, EDIT 19 onwards. See @Chris's comments also for good examples
[code]...
It's all gone quiet since Edit 19ish and @Chris reinforcing the issue with a good example (thank you Chris). I'll make the question a little easier (and attempt to tidy up all of the above), can anyone prove this is not an MS bug or similar? It seems to be something under the hood is not correctly wired up for VB.Net with regards to Nullable Structures and Events? However, all other cases using the Nullable Structures does appear to work?
Write an overload for every numeric type or if possible constrain a generic extension method to just numeric types.
View 2 RepliesIn C#, I could do something like this:
EventHandler handler = this.SomeEvent;
...which would allow me to, for example, do:
Delegate[] attachedHandlers = handler.GetInvocationList();
In VB.NET, I can't seem to figure out how to do a similar thing.
This doesn't work:
Dim handler As EventHandler = Me.SomeEvent
...due to the following error:
Public Event SomeEvent(sender As
Object, e As EventArgs)' is an event,
and cannot be called directly. Use a
'RaiseEvent' statement to raise an
event.
But this doesn't work either: [Code] So how can I actually get an EventHandler from an event in VB.NET? The only idea that's immediately coming to mind is to use reflection, but that seems pretty ridiculous.
I am trying to create a list of a generic type in vb.net 2.0 framework.
This is the generic type definition:
Public Class GenericParamMap(Of T)
Public Sub New(ByVal pParamName As String, ByVal pPropValue As T)
mParamName = pParamName
[Code]....
The compiler does not allow a "T" in the method's parameter because it's not defined, but I'm not sure how or where to define it. I thought it was okay to have a generic method definition.
I'm trying to code a class of RandomNumber. One of the class methods needs to populate a "List (Of RandomNumber)" ... which was passed as a parameter to the method ... with 10 random numbers between 1 and 50. DEAD SIMPLE :)
View 6 RepliesI have some code in c#
BeginInvoke(new MethodInvoker( delegate() {myAppMethod_Tick(sender, e); }));
Now, When I tried to convert that code to vb.net I have below..
BeginInvoke(New MethodInvoker(Function() Do myAppMethod_Tick(sender, e) End Function))
But it does not compile.. What's problem for it?
Because my c# application works ok without any problem..
may i know how to implement a delegate method into my project> currently i am using the serial port polling method by using a timer to read from the serial port, but now i am changing the method to delegate part.i have the code for the delegate part updating to the text box control but how do i modify it to update the mainform with my program codes.
The part for the delegate code is here
'---Event handler for the DataReceived event---
Private Sub DataReceived( _
ByVal sender As Object, _
ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) _
[code]....
I am trying to write a generic function that will check each database parameter to see if it is null, and if so, return DBNull; if not, return the object.So here is my function:
Public Shared Function CheckForNull(ByVal obj As Object) As Object
If obj <> Nothing Then Return obj Else Return DBNull.Value
End Function
[code].....
I have two class like this[code]...
The red code does not works. How do I get the type of data to declare, for example, a Specific Instance(Of integer) if Data is integer, and also Specific (of SomeClass) if Data is SomeClass?
I have a class C(Of T). I want to determine if some given value has type C, regardless of what T is. For example, I might want to determine if a value is a strongly-typed list, regardless what type of items the list stores. I just need to know how to do it in VB.net. In Java the syntax is like this:
var result = obj instance of Gen2<?>;
I'm looping all the properties in an object via reflection:
For Each p As PropertyInfo In values.[GetType]().GetProperties()
If p.CanRead Then
'Do stuff
End If
Next
how to determine whether the property in question is a generic List(Of T)? If it is I need to loop the list itself.
I've experimented with GetType and TypeOf but have not managed to get anything working.
To clarify, I want to keep this generic. I do not want to specify the type of T, I need to loop the list items and call the ToString method on each item. T could be one of a number of different types (application specific reference types). Is it possible to do this without specifying types?
(VB.NET 2005 with .Net 2.0)
i have issue returning a list in a web method. here is the code
<WebMethod()> _
Public Function getTags(para_parents As String) As List(Of getTypeDetailsByParentName_Result)()
Dim context As New PPEntities
[code]....
the error is
Value of type 'System.Collections.Generic.List(Of SaftyonRoad.getTypeDetailsByParentName_Result)' cannot be converted to '1-dimensional array of System.Collections.Generic.List(Of SaftyonRoad.getTypeDetailsByParentName_Result)'
it seems always at this time I cant figure out how to do something maybe it has something to do with lunchtime.
Im having trouble using a method that is defined by an outside company
This is a link to their integration guide:
[URL]
This is their documentation for the class Im trying to use
OrderQueryWebService Class
This class is for SID in particular and is made for use with the notification methods. This is for the Order Query Web Service specifically, allowing clients to return the status of transactions for their merchant, whenever they want to.
Methods
/ <summary>
/ Pass through the variables required and receive a list of Transaction
objects showing transaction status
[Code].....
The MerchantCode, the MerchantUsername, the MerchantPassword are all good the List is a custom type called SetComHash.Transaction
Everytime I try adding a string to the list such as the transactionNumber and some other values it gives me a type error:
"Value of type string cannot be converted to 'SetcomHash.Transaction'
