I am assuming "No", but I cannot find conclusive proof on Google to back this assumption. Using keywords of 'vb.net "generic operator overload"' yields exactly 1 result, and removing 'overload' gives more, but no direct statement to the issue.
My thinking is given an abstract class, it'd be great to be able to implement a generic operator overload that a derived class can use in such a case when said operator overload has to return a New copy of the derived class, yet the code for each overload is the same. If that makes any sense.
This touches back to my previous questions on my custom Enum class and overloading the bitwise operators (And, Or, Not, & Xor), but, this particular thought was prompted by a mere curiosity of "Can it be done?".
Here's what one of my custom enums basically look like:
The parent, EBase is nothing special, just hosting common Name and Value properties, plus two shared operators, op_Equality and op_Inequality.
Friend NotInheritable Class EExample
Inherits EBase
Private Sub New()
[Code]....
Then (in theory anyways), calling EExample.OneA Or EExample.FiveE would work because the compiler would know to call the generic operator overload from EBase, know that EExample.Enums matches the IEnums interface constraint, and automatically supply T.
That or I'm just swimming up a certain creek here without a paddle and over-analyzing things. But it's an interesting thought, no? What is StackOverflow's consensus? Do I need to lay off the Spice a little bit?
PS: I use /* */ style comments because Markdown doesn't handle VB-style properly.
PPS: I know that, in the last example, Return New T( ... ) is invalid, but I can't think of a proper syntax that would articulate the basic idea.
I have a question. In the framework, that was largely written before the generics came, you often see a function with lots of overloads to do something with different types. [code] and then have some kind of ifs/switch statements with typeof() to try to infer what the types are and what to do with them.What is best practise? Or what are the ideias that'd help me choose between a) and b)?
I read somewhere that older VB .net (pre VB .NET 2005?) couldn't use overloaded operators in a C# class. Is it true for overloaded cast operators?Either way do you guys think it's a disadvantage for a C# class library not to include them and arithmetic methods as actual methods for other languages, like:
I have defined a Sub in vb.net, with 'Of' type parameter like this:
[Code]...
I want to just add number1 and number2, But as you can see error has occured where i want to sum number1 and number2 saying that '+' is not defined for type 'VarType'. how to add these variables in Such Methods.
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?
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.
From what I can see online the Overloads keyword is optional but is there ever a time when it is necessary? It even seems to be an error when used in a Module.
What are the behaviors difference for the Previous Property of Other1 and Other2 Class.Note than the return type of the ovrloaded Previous Property of Other2 as bean changed to Other2 while it stay as Base for Other1.
Public Class Base Private _Previous as Base Protected Overridable ReadOnly Property Previous As Base
I am tightening up my coding with the Option Strict set to ON. It has now produced alot of errors. An example of this is:
If AllocatedDGV.Rows(i).Cells("RoomNumber").Value = RoomsAvailableDGV.Rows(j).Cells("RoomName").Value Then
It gives me the following error: Option Strict On disallows operands of type Object for operator '='. Use the 'Is' operator to test for object identity.
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 need to write an interface to get data to/from our data files.
We have a low level class that holds field values for each record read from the files.
This just holds two values, the value read from the file (DBValue) and the updated value that may need to be written back to the file (CurrentValue).
These values may be any of the standard value types (integer, date etc) or a string.
Either value (DBValue or CurrentValue) may be null if not defined.
I have written the class to manage this data which works fine while option strict is NOT on.
But we have an office policy of having option strict on all the time.
When I put option strict on, my object value comparisons fail with the error: "Option Strict On disallows operands of type Object for operator '='. Use the 'Is' operator to test for object identity."
Question, how should I change the following code to handle option strict on ...
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]
Do you really need this keyword to overload methods? What is the difference between using the overloads keyword vs. just having different method signatures?
I was familiar with the optional parameters in vb 6 and it made sense given the capabilities of the language but why the heck does VB.Net support optional parameters when there is method overloading? Which one should I use and is there a difference? If there is a difference when should I use each one?
I have recently come across some code that has the following. First there is a Interface with the following function Function Validate() As Boolean. That interface is then implemented in the an 'ABSTRACT' class like this. Public MustOverride Overloads Function Validate() As Boolean Implements IBusinessEntity.Validate
Question 1: Why use Overloads in the Abstract class implementation.
Question 2: The Abstract class is then inherited into a class (TestClass). In TestClass the Validate function is implemented as follows Public Overloads Overrides Function Validate() As Boolean. I understand the Overrides keyword is to insure that this is the version of the Validate that you want called and not the Abstract class version but why again use the keyword Overloads?
From what I understand you can overload a constructor of a class by simply changing the constructor signature. Also, you overload Methods and Properties of a class by using the Keyword Overloads. But why do it when your implementing an Interface method, or an Abstract Class method that's inherited.
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 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).
i'm accessing an access database and want to execute the following query
INSERT INTO sometable (date, field1, field2) SELECT ( ? AS Expr1, field1, field2) FROM othertable
? is a date i generate in code and field1,field2 belong to othertable i put it in a tableadapter and execute it by me.tableadapter.queryname(calculated date) but i get the error : Too many arguments to 'Public Overridable Overloads Function queryname() As Integer' Also if i try to generate the date in the query builder in the form dateserial(year(now),month(now),1-1)the query builder does not accept it?
I'm following this tutorial: [URL]..except I'm connecting to my own data source - a MS Access database.This is the query I have setup with the dataset:
SELECT Terminal_ID, SUM(Transaction_Quantity) AS Total FROM tblTransaction WHERE TransactionType_ID=3 and Transaction_DateTime>[@fromdate] GROUP BY Terminal_ID
The debug fails immediately because it needs the extra parameter so I change the code from:
Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 'TODO: This line of code loads data into the 'tetrisDataSet.tblTransaction' table. You can move, or remove it, as needed. Me.tblTransactionTableAdapter.Fill(Me.tetrisDataSet.tblTransaction)
[code].....
The error I get on build is:Too many arguments to 'Public Overridable Overloads Function Fill(dataTable As tetrisDataSet.tblTransactionDataTable) As Integer
...I gave it the extra parameter, so what gives? Something special I need to do as it's a datetime field?
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))
After having some trouble in my own code using String.Split and the Split(String(), Int32, StringSplitOptions) overload, I decided to look to the MSDN.I copied the entire VB.NET code example from this link: url...I placed it in a new class, and received the following errors (same errors as my own code example):[code]Why can my code not recogognize the string() parameter overloads to String.Split? Remember, i took the code from the MSDN link above, copied and pasted and it still did not work.I am counting on using the string() instead of char() overloads shown here: url...
