Way To Implement IComparable (Of T) Or IComparer(Of T) If Class Is Not A Generic Class
Feb 19, 2010
I am working on a general helper class to sort ListView SubItems. I wrote a base class that has much of the code I need. It includes a MustOverride for the Compare method so that the various inherited classes can implment their own comparisons based upon their type. For the value types, I end up with very similar code such as the following, where x and y are ListViewItems: Public Overloads Overrides Function Compare(ByVal x As Object, ByVal y As Object, ByVal sortColumnIndex As Integer, ByVal sortOrder As System.Windows.Forms.SortOrder) As Integer [code]
I am trying to create a class implementing the generic IComparer of my own class "Stellungen" (which translates to positions, like on a chess or checkers board).
This is what I got: Private Class comparer(Of Stellung) Implements System.Collections.Generic.IComparer(Of Stellung) Public Function Compare(x As Stellung, y As Stellung) As Integer Implements System.Collections.Generic.IComparer(Of Stellung).Compare End Function End Class
Problem is: inside the function I have no access to any fields of my class. If I start off with x. Intellisense will only give me .Equals, .GetHashCode - the methods you get on a type but not on an instance. Visual Studio 10 also highlights this, in the definition of the function the bits "x as Stellung" and "y as Stellung" are written in light blue, meaning it is a type and not an actual object. How do I access the things I want to compare inside my class?
I need to create unit testing project for my current website. The currentw ebsite si written in VB. All unit testing examples are using interface to create mock object. My current VB class does not implment any interface. Can I add interface and implement it to my current class and functions without affecting or changing codes to any pages in my website that call the functions? For examples my current class is like:
This question spawned from an example jmc gave to someone on how to use a structure to implement IComparable... now I always thought that structures could only be used to store basic things like this:
vb.net Private Structure PersonStruct Dim FirstName As String Dim Surname As String Dim HouseNumber As Integer End Structure
but it turns out you can define functions, subs, delegates and even events, all from within a structure. So that made me think... whats the real differences between a Structure and a Class? JMC highlighted one difference and that was not being able to create a new instance of a structure and pass in arguments to be initialized but apart from the lack of constructors is there really much difference? I assume there must be as Classes seem to get used a hell of a lot more than structures but I dont really understand why there is a need for both of them if they are so similar... I mean if classes have a few more features then why ever use a structure? Are they more 'lightweight' or something?
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 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]
If Class X is within the scope of Class Y, is X a subclass of Y?If Class A is a sub Class of B, then is Class B considered a super class of A?if Class C inherits Class D is Class D a superclass or parent of Class C?if Class E extends Class F then we can consider Class E a child of F?if Class G inherits Class H and is within the scope of Class I then who is the parent of Class G? Classes that inherits Class J and classes that are within Class J are all sub classes of Class J?
I need to have a dynamic URL preferably from a Test Classformatting this design pattern to handle dynamic links from tests. instead of a constant HomePageURL.
Namespace TestDesign Public Class HomePage Inherits IE
I want to modify the base Array class by creating a new class called "FileArray".I have some text files that are read into a string array. Each element in the array is a line from the text file. I want to update the GetValue method by overloading it or overriding it so that it will update some value that will give an indication to what the last line was. I have a couple of ideas on how I can do this:
1) Use a public integer, like intLine, that gets updated everytime GetValue is called.
2) Create a new property of Array, such as "LastLine" that would return the last line number (which would basically be the last index value +1) and then use a public array to store the files (though this is less desirable as the array may be used by several different functions)
An easier way would be to be able to determine the last element that was returned, which is basically what I think I am describing above.
Say I want to know more about a class mshtml.htmlinputelement for example.Say I want to know. What is his parent classes? What interface the class implement? How do I do so through object browser?
I have put this code in the global form Inherits System.Windows.Forms.Form. And then in the form that will inherit this from the global Inherits MenuStrip. "MenuStrip" is what the global form is called. But keep getting this error: Error1Base class 'MenuStrip' specified for class 'Lesson2' cannot be different from the base class 'System.Windows.Forms.Form' of one of its other partial types.
I have the following sample code in a VB.NET console application. It compiles and works, but feels like a hack. Is there a way to define EmptyChild so that it inherits from Intermediate(Of T As Class) without using the dummy EmptyClass?
Module Module1 Sub Main() Dim Child1 = New RealChild()[code].....
The other way to do this would be to move the generic code out of the Base class and then create 2 Intermediate classes like this [code]...
Then RealChild would inherit from the generic Intermediate and EmptyChild would inherit from the non-generic Intermediate. My problem with that solution is that the Base class is in a separate assembly and I need to keep the code that handles the generic type in that assembly. And there is functionality in the Intermediate class that does not belong in the assembly with the Base class.
I created two classes. One class is StudentClass and the other is HomeroomClass. The HomeroomClass contains a readonly property as a generic list of the StudentClass. [code]...
I am really trying to follow the DRY principle. I have a sub that looks like this?
Private Sub DoSupplyModel OutputLine("ITEM SUMMARIES") Dim ItemSumms As New SupplyModel.ItemSummaries(_currentSupplyModel, _excelRows) ItemSumms.FillRows()
i've got a Class like this public Class Cart(Of Item) Public Sub New(ByVal a As Integer, ByVal ParamArray items As Item())but i do not see how to create an instance of it: Dim block_names As New Cart(Of String, 5I)i get something like "type expected" o.O
We are developing an application for our shop floor. This program will be tracking material through the shop and we need to capture any errors the program generates, but we don't need to stop the program for all errors. I have some code to do a screen capture and put it in a database with exception.tostring data for debugging.
What we would like to do, is create an exception from the base class, but provide additional properties to allow us to set a severity and a user friendly error message. I would like to encapsulate this in a class that we would call in the catch of a try/catch, set the properties on the class, have the class record the data to the database, then raise the exception to the main program to display only the user friendly message and severity. The main program would then determine the severity and based on the severity stop the program or just display a discreet msg and continue to process.
Does anyone have an example of a custom exception class derived from exception that does something similar, or if I heading in the wrong direction, does anyone have a better solution?
ok this is the thing I have right now which is working quite well beside its a bit slow:
Public Function GetList() As List(Of SalesOrder) Try Dim list As New List(Of SalesOrder) Dim ds As DataSet ds = cls.GetSalesOrderList 'CLS is the data access class
I am creating a generic class that is Implementing IList(Of T) which requires that I implement the GetEnumorator of both IEnumerable(Of T) and IEnumerable. When looking at the members of IList(Of T) I see only one GetEnumorator function, yet it implements IEnumerable(Of T) and IEnumerable. How can I use one function to implement both interfaces when the function definitions only vary by return type?
Public Function GetList() As List(Of SalesOrder) Try Dim list As New List(Of SalesOrder) Dim ds As DataSet
[code]....
Now once I start retrieving more than 10000 records from the table, the loop takes long time to load values into generic class. Is there any way that I can get rid of loop? Can I do something like the following with the generic class?
txtSearch.AutoCompleteCustomSource.AddRange(Array. ConvertAll(Of DataRow, String)(BusinessLogic.ToDataTable.ConvertTo(WorkOr derList).Select(), Function(row As DataRow) row("TradeContactName")))
I am trying to serialize a class that contains a generic list, and I am finding it all works with the exception of the generic list property. That is to say the other properties are serialized fine and no error is produced.
I have in the past serialized an arraylist - but I thought it was possible to do a generic list in the same way.
Am I missing something or is it not possible to serialize/deserialize a generic list - I have read mixed comments on this..
The relevant parts of the class that gets serialized is defined as..
<XmlInclude(GetType(cConfigUser)), _ Serializable(), XmlRoot(ElementName:="Config")> _ Public Class cConfig
I have created a Interface and a couple classes that implement this Interface. I am in the process of developing a Shared Class that utilizes the functions that each of the individual classes have, due to the interface implementation.What i need to know is how do i develop this Shared Class so that way each of the methods within it are restricted to a single data type. This single data type needs to be restricted to any class that has implemented the Interface.
Some examples:
Public Interface IVector(Of T) Sub Add(ByVal v2 as T)
[code]....
As you can see it would allow me to develop one form, since i have standardized the required Subs/Functions for any class the implements the IVector interface. As i am still in developement, i was wondering if my current understanding of the method generics is correct in its current form or what i would have to do to make the Generic Shared Class work in the fashion that i am looking for in the example implementation.
