Deep Copy Generic List Of Classes
Aug 15, 2006
If I have a generic.list(of ClassA), is there a simple way to create a deep copy of this list that will not affect the original copy? It seems to work if I have a generic list of Structures, but for some reason the copy constructor for lists of classes only copies pointers to the elements (or maybe a pointer to the whole list?). I would move to structures if it were not for the fact that I can't find a way to edit the members in the structs in the list. eg:list(0).a = 5 'Does not workIs there some way to get around this without declaring an instance of that structure, like this:dim str as StructA = list(0)str.a = 5I'd
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Dec 16, 2009
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.
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Dec 1, 2010
As I understand it a shallow copy is like a CLONE copy of an object where the values for each property are independent of one another whereas a DEEP copy is a copy that uses the same memory locations and therefore if you change a value in one it is also shown in the second item ( By Reference to the same memory locations ).So my main question is, when dealing with CLASSEs, STRUCTUREs etcetera containing REFERENCE types.is there anyway to quickly create a CLONE or shallow copy of an OBJECT or not ? The only way I can think of is to put the item into a one dimensional array and use the CLONE method for an array. [code]
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Jan 31, 2010
Is there any way possible to deep copy a Control? Just want to know if its possible
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Jan 20, 2010
I have created a form with a tab control that I want to be able to make a copy of in such a way that all the child controls and their data are copied as well. I have tried this:
Dim NewPage as TabPage = tcViews.TabPages.Item(0)
tcViews.TabPages.Add(NewPage)
I end up with a reference to the first page. That is, if I change something in the old page, it changes in the new one as well. I believe this is because VB.NET treats assignments of classes as references, rather than values. Hence only the memory address of the original is copied, so essentially both refer to the same tab page in memory. I also tried serialization and deserialization.
The TabPage is apparently not serializable. And I heard about MemberwiseClone, but it isn't accessible, according to Visual Studio. There doesn't appear to be a Clone method available either. How do I make a new tab page that is totally independent of the original, but that has copies of the original page's controls and their property data, which can then be edited independently of the originals?
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Aug 5, 2011
If I instantiate an object within a function in VB.NET and return it, does it return it be reference or by value. IE - should I be worried about performance if I write something like this:
Public Function ret_obj_func() As big_object
Dim ret_obj As New big_obj(<lots of stuff>)
Return ret_obj
End Function
If I call this function from somewhere else, will it instantiate the object in the ret_obj and then create a deep copy to pass back a copy to the caller, Or will it just pass back a reference?
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Feb 6, 2012
I am trying to make a deep copy by adding a clone property to my class.
[Code]...
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Apr 27, 2009
Essentially what I want to do is copy a WebBrowser object such that I can do the equivalent of "Open In New Tab" or "Open In New Window" actions, maintaining any posted data. I don't just want to navigate to the same URL as in the original WebBrowser object, rather I want to repeat the HttpWebRequest.
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Mar 13, 2010
I have a button ad a list box, the button when clicked lets the user select a directory on the HDD, and then the app is meant to list all the sub directory's of that folder int he list box. However I cant seem to get it to list just the sub directory names, not the full paths, and also to only scan by 1 folder deep (selected foldersub folder).
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Jun 30, 2011
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.
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Jul 28, 2010
This is the code I'm trying to develop:
Public Structure Statistic(Of t)
Dim maxStat As t
Dim curStat As t
[Code].....
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Mar 21, 2012
I have a generic function in VB.Net. I also have two classes called A and B. Is it possible to allow the generic constraints on my function to allow the Type to be either class A or B? Class A and B do not share any base classes except for object.
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Aug 2, 2010
I need to create a generic for all the classes having common data.I am having a Test.xsd dataset.In that dataset I am having 3 Table Adapter.
pgaddressTableAdapter1
pgaddressTableAdapter2
pgaddressTableAdapter3
Code is here. You can see all these classes having same methods. I want to create a generic class for these class.
[Code]...
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May 25, 2010
I'm trying to create a base interface for a class of mine that uses generics. However, I cannot figure out how to declare a property of the interface when its type won't be defined until the class is initialized.
To clarify, consider List(of T), which according to msdn, implements IList (among other things). Note that IList is not the same as its generic counterpart IList(Of T). So that mean any List(of T) can be converted to IList, which simply returns an object for its items. That's what I want to do with MyClass(of T), be able to cast it as IMyClass regardless of what T is.
But when I try such as:
Interface IMyClass
Prop A as Object
Class MyClass(of T) Implements IMyClass
Prop A as T Implements IMyClass.A
I get a signature error for the last line, even though object is broader than T. What am I doing wrong, or how exactly did Microsoft manage to make List(of T) implement IList?
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Jan 27, 2010
I have an interface that i have declared some of the basic internal functions, subs, properties, etc. This interface is then implemented into 3 pre-defined classes. These classes are end-use classes so they dont get derived or inherited elsewhere. I am trying to create a generic shared class that can operate on each of these 3 predefined classes and potentially more as long as they implement the interface.
[Code]...
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Oct 1, 2009
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)
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Mar 23, 2011
Public 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?
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May 3, 2012
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)'
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Apr 7, 2011
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'
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Oct 29, 2010
What would be the fastest way to sort a list that contains a list of objects, based upon another list? An example follows:Say I have multiple lists of employees. Each individual list has a common property value, say "Department". So I have a list of employees, in one list they all have the department string value of "Sales". In another list all the objects have a department value of "Finance". These lists of employees are then contained in a list which holds them all.
I have a second list, which should drives the sort order of the employee lists. The second list simply contains a list of strings like, "Finance", "Sales", "IT" and so on. I'd like my lists of customers to be sorted in the order of "Finance", "Sales", etc.I'm using VB.NET in .NET 2.0
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Jan 5, 2011
Dim x = GetType(List(Of )) 'valid statement
Dim list As New List(Of String)
Now I want to see if list is a List(Of T) variable: Dim isList = TypeOf list Is List(Of ) On the last line I get a compile error: "Type Expected". Is there any cheap-performance TypeOf operator alternative for generics?
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Mar 12, 2009
I have converted c# .cs to vb:= I have 6 errors on:
Red "List" says Too few type arguments to system.Collections.Generic.List(Of T)'
Orange "Calendar" says Value of type 'System.Windows.Forms.Control.ControlCollection' cannot be converted to 'Form1.Kobush.Windows.Forms.Appointment'.
[code]....
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Oct 26, 2011
This is probably a really basic question - but I have a list of items (custom objects) being passed from one winform (.net 3.5) to another. I want to create a local list to store changes that only get persisted if the user clicks save. Currently if the user clicks cancel - the changes are still applied in the first form because I assume the objects are reference type.I have the save working as it calls a service layer to do the save and then refreshes the other form - but not the cancel.
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Oct 13, 2011
i m getting a collection of data in list's object. And from this list i want to get the maximum id.`
Dim objinfo As List(Of AlbumInfo) = objPhotos.GetPhotos_Alb_ID(Me.ModuleId, hdd_AlbID.Value)
Dim Photo_Image As String = ""
Dim str As String = Photo_Image & fu_Photo.PostedFile.FileName.Substrng(fu_Photo.PostedFile.FileName.LastIndexOf("."))
[code]....
this returns the "0"th positions id from Convert.ToString(objinfo.Item("0").Photo_Id + 1)but i want to get the last item's id.
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Jan 5, 2011
i have list of string like this :
Dim totalPrice As New List(Of Integer)
how can i get sum of column(0) (C# or VB) ?
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Jan 17, 2011
<div class=PhorumReadBodyText>Hi, I have a problem with adding of items to generic list, problem is when I insert 1. item to the list, everithing is ok, but if I insert second item, first and second has same values.
code looks like that (asp.net 4.0): </div> <div class=PhorumReadBodyText> </div> <div class=PhorumReadBodyText>Partial Class _Default
Inherits System.Web.UI.Page
[Code]...
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Jan 17, 2011
I have a problem with adding items to generic list, problem is when I add 1. item to the list, everything is ok, but when I add second, first and second has the same values...
This is code (asp.net 4.0):
Partial Class _Default
Inherits System.Web.UI.Page
<Serializable()>
Public Class Product
Shared Property Material As String
[URL]
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Aug 26, 2009
In my VB.net application I am populating my customer object and looping through it as shown below.As there are thousands of customers, I want to do it 500 customers at a time.Is there anyway I can have one more For loop to process 500 customers at one shot in vB.netI am not using LinQ as the database is Oracle.[code]
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Apr 30, 2010
I want my loop to loop until it reaches the last string in my generic list. I know I could simply insert the last index of the list as an integer but I want to be able to use this if my list grows too. How could I achieve this?
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May 14, 2009
I have been reading extensively about searching generic lists in VB.NET with the usage of delegates.However, I still cannot seem to grasp how to achieve what I want to, which I believe is frustratingly simple! I have a list populated with instances of an object with three parameters (fields/ variables).When I receive a new object to add to the list I want to search the list for the "layer" field.If the field matches then I will replace that row (object) in the list with the new object, if no match is found then I will add it to the list. [code]
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