Whats the difference between these two initialization methods for obj? I've seen both of these, but know know if there is an appropriate time to use one vs the other. I found this post which covers C#, but not sure if the same applies to VB.Net.[code]
View 3 Replies
How should class member variables be used in combination with class methods?Let's say I have a class 'C' with a member variable 'someData'.I call C.getData(), which does not return a value but instead puts data in C.someData. The class that instantiated 'C' first calls C.getData and then uses the data by accessing the member variable C.someData.I call C.getData() in the class that instantiated 'C' which is a function that returns data.I myself prefer the second way. But it also depends on the situation and it's a small difference. Is it 'bad' to have class methods that depend on the classes internal state? What are the best conventions?
View 2 RepliesI have main class of Races with mulitple properties. One of those properties has been defined as another class Runners.
So I have a race with multiple runners and when I try to update the data i get an instantiation error.
For the life of me I can't get it to work.
This is what I am trying to do...
In the clsRace class I have defined :
PublicProperty clsRunner(ByVal index AsLong) As clsRunner
Get
[Code].....
I am not sure how clear my question is by the title, but I am trying to make Class methods instead of Instance methods in Visual Basic that way I don't have to waste memory and code creating temporary objects to execute methods that don't need instance variables.
I am not sure if you can do that in VB but I know you can in Objective-C by using either a "+" or "-" sign in front of the method declaration. And in C++ (at least I think, I can't remember) you put the static keyword or const keyword in front of the function.How would I do this in VB if it is possible? Or should I just make a separate set of functions that are not members of a class?
i want to create an anonymous class in vb.net exactly like this:
[Code]...
Private Delegate Sub SetControlValueCallBack(ByVal value As Integer)
View 3 RepliesWhat is the difference between the following two statements (in terms of memory management):
Dim frm as New MyForm()
frm.Show()
VS
MyForm.Show()
I am originally a C# developer, how does the second one make sense or even compile for that matter in VB.NET? (Show() is not a Shared/Static method) What is happening in the second case?
When starting my application, I have a couple of classes which are required to read certain files in order to create a set of default data. The logical place (to me) to do this is in a Shared class constructor; the idea would be to throw a class-level event if the reading of the defaults file fails. Unfortunately, this does not work as attempting to access such an event, in order to attach a handler to it, fires the class constructor before the event has been attached. In a failing case, the constructor starts, fires the fail event, the constructor completes, and then the event handler is attached, after the event has fired.
The only other solution I can think of is to give the class a "typeInitialisedSuccessfully" boolean property and put a try/catch block around every call to construct an instance of the class, which seems unnecessarily kludgey to me. Can someone suggest a more elegant solution?
EDIT: Because this is a fundamental Class, used in one form or another across nearly all of our software tools, I would greatly prefer a solution that will notify future programmers that the type initialiser needs to be called, which is why I initially went towards the Shared Constructor as a solution.
In VB.Net is there any difference between the following three ways of initializing object variables
Method 1
Dim commandObject As SqlCommand
commandObject = New SqlCommand("MadeUpCommand")
Method 2
Dim commandObject As SqlCommand = New SqlCommand("MadeUpCommand")
Method 3
Dim commandObject As New SqlCommand("MadeUpCommand")
Is one more efficient than the others, or are they effectively all the same?
I want to know what are classes , objects , a namespace , subroutines,functions,methods,properties and differemce betweem byval and byref in your words.
View 18 RepliesI can't make difference between public class and private class and friend and protected friend class.
View 1 RepliesClass Foo
ReadOnly name As String
Public Sub New(name As String, dependentUpon As Foo)
Me.name = name
[code]....
The output of New Bar() is:
Dependent created. Dependent upon nothing.
Independent created. Dependent upon nothing.
It seems fields are initialized in the same order as they appear in the source code, which (a) leads to an unexpected result, and (b) seems a little puzzling, given that one is normally not permitted to read from uninitialized variables in .NET, yet that seems to be working fine above.I would've expected VB.NET to be smart enough to initialize referenced fields first, and only then those that reference it; i.e. I'd have liked to see this output instead:
Independent created. Dependent upon nothing.
Dependent created. Dependent upon Independent.
how to get VB.NET to behave like that instead, without simply having to swap the declaration order of dependent and independent inside class Bar?
how do I overcome it? I have created a class and compiled into .dll This code
[Code]...
In Visual Studio 2008, if I do this:
[Code]....
Does anyone here know how to get the above to work WITHOUT warnings being generated?
In the following code i get a warning at line 59:Warning 1: Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated.and.. At line 78 I get this Warning:
Warning 2 Property 'SelectedCustomer' doesn't return a value on all code paths. A null reference exception could occur at run time when the result is used.
The program compiles and runs well, but i cant' undesrtand the reason for these warnings. Any Idea ?
1: Public Class Form1
2:
3: 'Form level members
4: Private objCustomers As New ArrayList
[code]....
my question is simple. How do i add methods to the standard DataGridView control of VB.NET
I want to add some methods of my own to the class, but i tried inheritance and i get errors. What are the techniques out there to extend native classes in vb net
Example ^. I must be forgetting something or being really dumb.
View 3 RepliesIn this project I am making a grade calculator; I am modifying an existing code I have to have the following characteristics: I need to modify the DetermineGrade method so that it accepts the maximum number of points that can be earned on both tests (currently, the max number of points is 200: 100 points per test). For an A grade, the student must earn at least 90% of the total number of points. For a B, the student must earn at least 80%. For a C, at least 70%. For a D, at least 60%. If they earn less than 60% of the total points, then grade is F. Here is the exisint code I have for the DetermineGrade method specifically:
Public Sub DetermineGrade()
Dim intTotal As Integer
intTotal = _intScore1 + _intScore2
[code]......
I am trying to add shared members in derived classes and use that values in base classes...
I have base
class DBLayer
public shared function GetDetail(byval UIN as integer)
dim StrSql = string.format("select * from {0} where uin = {1}", tablename, uin)
end function
end class
[Code]..
currently there is error using the tablename variable of derived class in base class but i want to use it i dun know other techniques if other solutions are better then u can post it or u can say how can i make it work? confused...
Cannot appear to be able to get this function to not have the above error.Private Function GetIncidentActions(ByVal FromAgentID As Integer, ByVal ToAgentID As Integer, ByVal incidentAction As Integer, ByVal ActionDate As Date) As String
[Code]...
I have a class definition that I've seen other define properties that return collections of objects.
Public Property GetAllAdults() as Adults End Property I made the argument that this should be a method in the class, because it doesn't define an attribute of the class, and could not be extended with parameters. Is/Are there reasons why this should be defined as a property vs. a function?
I have a Public Class called "ClientConnection". Inside that class, I have a Public ReadOnly Property called "FileTransfers(ByVal TransferID)". The property returns an object of the class "FileTransfer". All methods in FileTransfer are set to public.
VS is able to discover the methods inside the parent class "ClientConnection". How would I expose the methods inside the sub-class "FileTransfer" that is returned by the property "FileTransfers(ByVal TransferID)"?
Public Class ClientConnection
'irreverent code removed
Public ReadOnly Property FileTransfers(ByVal TransferID As Integer)
[Code].....
I have a database table called Job. I have mapped this table using LINQ to SQL so that I have a class called Job.
What I want to do is add some methods to the Job class. The Job class is defined in the LINQ to SQL classes .dbml file. So, in order to add methods, or anything else to the Job class what should I do?
Should I create a partial class named Job and define the methods in there? Will that then get mixed in properly? Not sure how to proceed on this one.
Do I have to instantiate description every time for different method? Or should I use static? Here's how I'm doing this now: What is the best way of handling this kind of situations. it seems that I repeat this line:Dim description As BLLDescription = New BLLDescription() without any good reasn.
Protected Sub Button8_Click(sender As Object, e As System.EventArgs) Handles Button8.Click
Dim description As BLLDescription = New BLLDescription()
[Cdoe].....
I have a function that 2 derived classes use, but the third doesn't, would it make sense to just leave it in the base class, even though one of the 3 derived classes doesn't use it?The only way I could think of disallowing the third class is to basically create an intermediate class that is derived of the base, then the 2 that use the common function are derived off the second class.
Is it possible to prevent the 3rd class from using the function, while letting the two that are supposed to use it, use it?Does that just seem to go overboard, I mean as long as I don't "try" to call the function from the 3rd class, it shouldn't be a problem, I just was interested if there was a way to prevent it all together without a lot of hassle.
Is it possible to iterate through the properties and methods of a custom class, getting the details about those properties and methods in the process.[code]....
View 2 RepliesI have a database table called Job. I have mapped this table using LINQ to SQL so that I have a class called Job.What I want to do is add some methods to the Job class. The Job class is defined in the LINQ to SQL classes .dbml file. So, in order to add methods, or anything else to the Job class what should I do?Should I create a partial class named Job and define the methods in there? Will that then get mixed in properly? Not sure how to proceed on this one.
View 2 RepliesI have a database table called Job. I have mapped this table using LINQ to SQL so that I have a class called Job.What I want to do is add some methods to the Job class. The Job class is defined in the LINQ to SQL classes .dbml file. So, in order to add methods, or anything else to the Job class what should I do?Should I create a partial class named Job and define the methods in there? Will that then get mixed in properly? Not sure how to proceed on this one.
View 1 RepliesIn VB.NET or C#, is there a way to determine if a class has been extended with extension methods?
View 3 RepliesI created a Class that inherits List(Of TKey, TValue) and adds a few functions. Its purpose is not to add items to it at runtime, but when it is initialized. I would actually like to remove the add/delete methods from the class (as it currently exposes them from the inherited class).
[Code]...
