I was developing a small function when trying to run an enumerator across a list and then carry out some action. (Below is an idea of what I was trying to do. When trying to remove I got a "Collection cannot be modified" which after I had actually woken up I realised that tempList must have just been assigned myLists reference rather than a copy of myLists. After that I tried to find a way to say
[Code]...
I have a method where I'm taking a generic object and using TypeOf to check what has been passed through. Now I would like to pass it a List(Of T) (T being anything) and no matter what T is I'd like to do the same thing to this list. I tried the following:
public sub foo(ByVal obj As Object)
if TypeOf obj Is List(Of Object) Then
'do stuff
end if
end sub
but this doesn't seem to work if I pass it List(Of String), say. I suppose that List(Of Object) and List(Of String) are being treated as different objects, but I thought that since String is an object, the comparision might work.
Now I realise that this is as ugly as sin and I'm better off overloading the method to take List(Of T) as its parameter, but I'm mostly asking out of curiosity: is there a way of comparing the types List(Of Object1) and List(Of Object2) and getting a positive result, since they are both just List(Of T)?
I have a utility class that takes a generic list as a parameter.Code looks like:
Function DoStuff(collection as Object, elt as Object)
...
collection.Add(elt)
[code]....
I've created a two-worksheet template in Excel - the first sheet is for pretty charts, and the other sheet is for the data that drives those charts. I've written a vb.net 2005 app that can dump in all my data on the second worksheet, and the chart worksheet updates perfectly.I would like to do this report several times over in the same workbook. (So the tabs would read 'Person1 - Chart', 'Person1 - Data', 'Person2 - Chart', 'Person2 - Data', etc.)
My solution was to, for every person this report was going to be run for, copy the chart template, and then copy the data template. The problem is that every chart template that is created points to the original data worksheet. How can I set what worksheet each chart worksheet is pointing at?
I'm using VB.NET with .NET 2.0. I have two lists, and I want to compare the lists on a specific property in the object, not the object as a whole, and create a new list that contains objects that are in one list, but not the other.
myList1.Add(New Customer(1,"John","Doe")
myList1.Add(New Customer(2,"Jane","Doe")
myList2.Add(New Customer(1,"","")
Result in the above example would contain one customer, Jane Doe, because the identifier 2 wasn't in the second list.How can you compare these two List<T> or any IEnumerable<T> in .NET 2.0 (lacking LINQ)?
I have recently moved from VB 2003 to VB 2005. While I am finding a lot of the new features quite useful, I am having trouble with List (of T). I want to be able to do something like this
Function GetList(MyObjectType as Type) as datatable
Dim list as new List(of MyObjectType)
End Function
Function GetList(MyObjectType as String) as datatable
Dim list as new List(of GetType(MyObjectType))
End Function
VB 2005 does not allow me to do this at all. Must the "type of" be srongly declared at all times? Can't this be done dynamically?
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.
If I increase the capacity of a given list, or add elements until count>capacity, does this mean the program is actually copying the entire list's contents to a new space in memory (similar to redim preserve with arrays)? If so, than I have really been hurting the performance of my lists, as before I was inserting and adding without a second thought. This seems a strong restriction on the dynamic abilities of lists.
View 2 Repliesi have created a list of buttons using the following
Dim Butt(20) As Button
Dim i As Integer = 0
While (i <= 20)
Butt(i) = New Button
Me.Controls.Add(Butt(i))
i = i + 1
End While
this means that buttons are created in the code and not on the form to begin with, so I don't know how to create an event for the click of a button in a list. Is it possible to do it with a parameter for i so that there is only 1event for all buttons in the list, and i is the button index array clicked?
I want to create a generic list - but I want to specify the type at runtime - is there a way I can do this? using reflection perhaps?Something like this...
Public Shared Sub create(ByVal t As Type)
Dim myList As New Generic.List(Of t)
End Sub
Here are essential excerpts for the code creating the class and the page using it:
Imports System.Collections.ObjectModel
Public Class Test (Of T as xyz)
Inherits Collection (Of T)
[code].....
I have Crystal Reports 2008 installed on my win7 laptop but when i go to insert references from my application settings the CrystalDecisions references are missing and im not able to find them. Note: they do exist in my "c:windowsassembly" folder.
View 3 RepliesI am new to VB.NET, just landed a job fresh out of school (well still in school), but I am having trouble with VB...alot of it is getting used to the IDE itsself (we use VB 2010).t does alot of the work for you which is cool but I am having some trouble understanding some concepts.Here are my questions: How to call classes named an initialized on a DSS skeleton to a new page. And the functionalities of building a collection. (also the differences of a generic
View 5 RepliesI have 3 similar functions, that only change based on numeric type:
<Extension()> _
Public Function ToNullableShort(ByVal str As String) As Short?
Dim intReturn As Short
[Code].....
I was trying to make a generic function out of this, but couldn't do it. How can I make a generic function that will take a specific T and make it a Nullable(of T)?
I have a gridview which can be filtered from one or more values in a querystring. That all works great: e.g. "?subject=Maths&authorName=Bond_James&type=Magazine" The values passed to the query string come from 3 drop down lists: Subject, Author, Type.What I'd like is when the user presses "Filter" it will take the selected values from the drop down lists and pass them to the querystring - it could be 1 value, 2, or all 3 (like above).
The drop down lists have an item called "All Subjects" / "All Author" / "All Type" each with a value of -1. The idea being that if the user leaves these items selected then the Filter button just ignores them.
Here is my code so far:
Protected Sub buttonFilterGo_Click(ByVal sender As Object, ByVal e As EventArgs) Handles buttonFilterGo.Click
Dim queryString As String
Dim selectedAuthorString As String = "author=" & dropAuthorList.SelectedItem.Value
[code]....
Also, one more thing. How do I get the drop down lists to have the filters selected when the page re loads?
EDIT: I changed the default values of the drop down lists to "" - this leaves the URL looking messy though ?author=&subject=&type= This works, is it the best way?
I have two lists. One list is a list of names, the other list is a list of how many times each name is found in the first list noted in the database
so...
Nick
John
Jim
Jack
is the firs tlist
10
13
13
2
is the second list. Nick had 10, john 13 and so on.I want to sort the second list from large to small, but have the index for the first list still linked to the correct amount of calls.i do it this way so I can
for x = 0 to num_of_names
string = lst_name(x) & "-" & lst_count(x)
next x
We have migrated our Vb6 application to VB.NET using a third party tool. Now we are in a process of Refactoring and introducing object oriented concepts in the application.
In VB6, we were using structures in many places. As a part of introducing object oriented programming,
1. is it a good idea of changing all Structures to Classes? or Is there a concept of "Generic Structure" similar to Generic collections, Generic classes?
2. Can some one guide me any source containing guide lines or best practices for applications that are migrated to VB.NET from VB6 and implementing object oriented programmaing.
I have a copying error with my program. I am trying to copy the internet cache folder, and the error states that some files cannont be copied (read only maybe?) How can i make it copy, or just skip the uncopyable files?
My.Computer.FileSystem.CopyDirectory(Environment.GetFolderPath(Environment.SpecialFolder.Internet Cache), "d:My Documents")
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 have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
I am trying to construct a generic interface class with generic functions. My goal was to use this to implement multiple worker classes for database interaction that have the same basic functionality. Each class will deal with different object for example, category, product or supplier but unless the the functions in the interface are generic that this won't work.This is the interface code that I have but I don't know if I have done it correctly. [code]
View 2 RepliesI know how to check whether an item exists in a list using (MyList.Contains), But I do not know how to check the whole list. For example (use one button and one richtextbox):
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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]...
If i have an object that implements an interface (and don't know the exact object) i can call a sub (DoSomething) by going:
vb
Dim iObj = trycast(something, iInterface)
if iObj isnot nothing then
iObj.DoSomething()
end if
How can I do this for a Generic? such as...
vb
Public Class TestClass(of T)
Public sub DoSomething()
....
end class
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]....
I can do this without problem.
Class A
End Class
Class B : Inherit A
End Class
Dim Obj1 As A = New B
I want to add References from my another project. How Can I do that.
View 3 RepliesI code primarily in vb.net. I've been doing basic dependency injection manually and am looking to learn more about DI/IoC and maybe use a DI/IoC framework/container like Ninject. There are lots of examples and write-ups using Java and C# code. I'm looking for the best resources for vb.net programmers. Likewise, is there a particular framework that would be easiest for a vb.net programmer to pick up?
View 3 RepliesI am trying out Modi but i cant seem to find the references to add. I have office2k7 but cant find Microsoft Office Document Imaging 12.0 Type Library in com tab. Also cant find the dll in C:Program FilesCommon FilesMicrosoft SharedMODI
View 2 RepliesI am using vb.net 2005.After I rebuild the solution that has many projects, some references in a project are always dropped.I have to manully add them again.
View 1 Replies