Pre-defined Class In .net 2.0 To Hold A Single Generic-typed Mutable Field?
Jun 20, 2011
In a number of my projects, I find myself declaring a rather boring class:
[Code]...
to e.g. allow an object to give information to another object in such a way that the information can be mutated later wherever it goes. For example, in a Dictionary(Of String, Holder(Of SomeImmutableType)) it's possible to update the thing of SomeImmutableType without having to change the Dictionary itself (since the Dictionary's entry for a given key will always contain the same Holder object, that Holder object may be used as a lock).
[Code]...
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Jan 21, 2010
I can do this without problem.
Class A
End Class
Class B : Inherit A
End Class
Dim Obj1 As A = New B
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Oct 19, 2010
Consider a MyForm class that contains a shadowed implementation of Show(). It also contains a CreateForm() method, which accepts an instance of the form and calls the shadowed sub:
[Code]....
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Apr 13, 2012
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.
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Aug 14, 2010
I have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
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Nov 25, 2011
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]
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Aug 21, 2009
Is there anyone who knows how to set a field value to a value that I typed? I have an Xtragrid, binded to sql database and I wanna set the dateedited column to todays date when user changes any field on the grid . Since I'm using devexpress I can't just type columnname and set the text to the value I wanted.
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Mar 16, 2010
I am using Dataset created by the wizard with BindingSource and Binding Navigator
For example, I placed a Textbox on the form, and bind it to a field.
I was trying to compare the field value stored in the sql server database with the data I have on my form.
Let say I run the form, and Textbox1 get it is value from the first row in mytable from BindingSource (let say value 1000) [code]...
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Jan 17, 2012
I am using a Strongly Typed Dataset as DAL. I want to return a single column from my table for that i wrote the code as
SELECT DISTINCT Floor
FROM Room
WHERE (Building = @Building)
But when i previewed the data, it shows me all the columns of the table with Null Value and the column with primary key has -1 value. This condition raise an Exception when i link this query to a ComboBox ..
cmbFloor.DataSource = da.GetFloorByBuilding(cmbBuilding.Text)
cmbFloor.DisplayMember = "Floor"
Error: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.
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May 7, 2010
I am trying to use the DGV to view various properties from a variety of different class instances. Is it possible to bind each cell individually?
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May 21, 2009
I have Visual Basics 2008 express and I tried to make a autotyper, so this is my
Button1: Timer1.Start
Timer1: Timer2.Start
Timer2: SendKeys.Send(Textbox.text)
Button2: Timer2.Stop
So it was my first try ever with VB and it kind of worked... Only 2 problems;
1. Button 2 doesn't really work, I have to click it really many times, then go to a different window, then click it really many times again, in the meantime it keeps on spamming
2. How do I make my autotyper press enter every single time after the textbox message was typed?
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Jul 20, 2010
The problem is, I've never created a class before, not in VB, Java, or anything. I know all the terms associated with classes, I understand at a high level how classes work no problem. But I suck at the actual details of making one.[code]...
As for the Getter and Setter, the reason I put the question marks in is because I want to return the whole array there. The class will eventually have other properties which are basically permutations of the same data, but this is the full set that I will use when I want to save it out or something. Now I want to return the whole Array, but typing "Return fullDataSet()" doesn't seem like a good idea. I mean, the name of the property is "fullDataSet()." It will just make some kind of loop. But there is no other data to return.
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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]
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Dec 15, 2010
I have an interface 'ICRUDable' and a class called ClientAddress which implements the ICRUDable interface.
My understanding of OOP would lead me to believe that if I declare a System.Data.Linq.Table(Of ICRUDable) then I should be able to put ClientAddress's in there.
The code I have tried includes;
Dim dc As New CRMDataContext
Dim items = dc.ClientAddresses
and
[Code]....
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Nov 20, 2010
I'm trying to create a strongly-typed Dictionary class in VB.NET.I'm tired of typing Dim people as Dictionary(Of String, Person)and want to make a PersonDictionary class so I can say Dim people as PersonDictionary.My reference material says to create a new class that inherits the DictionaryBase class. Then override the Add, Remove, and Item Sub/Properties.It seems like a pretty common pattern, is there an easier way?
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Mar 10, 2009
I need a simple class with only one Public property and no Public methods (the final Class will be more complex, but for testing this is all I need). The Property is "Item" and takes a "String" as a parameter. It returns a "String" based on the parameter. I then want be able to add instances of this object to a List or Array, and then Bind it to a Repeater or a ListView......most importantly, I want to be able to then refer to values in my simple Class via the Eval function:
<%# Eval("SomeIDString**") %>**.
I can't Bind at all unless I declare the Item property as the Default property...why?
When I use "Eval", I get an error in the lines of "[some property] does not exists". indeed it doesn't, because everything is accessed via the Item property. it then does works if I replace "Eval" with "Container.DataItem". Is there a way to use Eval instead of Container.DataItem? I would rather not have my class inherit any other classes because I want to keep it clean from supurfulous properties and/or methods.
Are there interfaces I need to implement? Also, the reason I want to use Eval, is that as much as possible, I want to make the use of this Class simple, so the coder doesn't need to worry about special cases. I just want it to work, much like the DataTable Class, but with a much simpler, lighter-weight implementation.
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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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Apr 24, 2010
I am developing a new project for my daily office use using access database with vb 2005.
In this project I have one bounded datagridview and it is ready to use.
I want to alter a particular field value in the datagridview regularly. so whenever I click the rowheader that particular field should be editable with a combobox with some value, after selection of the value and leaving that particular cell it should be updated with the appropriate record in the database.
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Mar 9, 2010
with editing a single field of a database. variable dS is my dataset variable in which i have filled with the tables of my database. since its my first time in database management with vb.net
Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
If txtPOno.Text = "" Or txtDate.Text = "" Or txtSuppCode.Text = "" Or rBOM < 0 Or
[Code].....
inorder to pass. honestly, i really think that im using a BRUTE FORCE method.
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May 9, 2012
can someone please help me with a textbox? I have created a new class and require this textbox field within a sub in the new class but i get Error1 'TextBox1' is not declared. It may be inaccessible due to its protection level.I have tried MyClass.TextBox1 = Form1.TextBox1 but I get declaration expected.
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Feb 14, 2012
In trying to add a bit of usage variety to a generic class I'm working on, I ran into this issue with trying to cast an object into an interface instance where the interface is defined inside the generic class.
[Code]...
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Jan 20, 2012
Is there a way to define a class such that there can be only a single instance of that class?
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Sep 15, 2010
I have a column in a table that contains a message and I want this message to be displayed in a label. Here is my code which currently doesn't populate the label.
Protected conString As String = ConfigurationManager.AppSettings("sqldirectory")
Dim cnn As New SqlConnection(conString)
Dim cmd As New SqlCommand("select message from [database].[dbo].[table]")
[Code]....
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Mar 20, 2009
I'm using an access database in a program that I'm making for my school, the user is able to select an item from the menu, then it sends it to a list box, there is also a textbox to put a quantity of how much of the item you want. I have a field in my database called Amout Ordered, I want to update it with the amount of each item ordered, and I can't figure out how.
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Apr 30, 2009
What I'm trying to do - VB 2005 express and sql 2005 express editions - Trying to set up just a basic hardware/software inventory program. As is I've got separate tables for computer and software licenses...with ComputerID and LicenseID primary keys respectively...where I'm bumping into walls is that I wanted to be able to link them together with a foreign key, for example the computer record would have a foreign key for LicenseID and when a license would get installed the ID would go in and there'd be a nice pretty link. However I run into scenarios where a computer might not have any software installed...or might have more than 1 software item. Or a single software item may be installed on 1 computer, multiple computers, or nowhere. It possible to have that single foreign key field link to multiple records from the opposite table?
What was originally suggested to me was to have a 3rd table called Installations. It'd have 3 rows...one named InstallationID as the primary key, and 2 foreign key rows named ComputerID and LicenseID that linked to the other tables, so that when a license was installed, a record would be added to the Installations table, and later on when we wanted to see where all a particular license was installed or what licenses a single computer had, the table could be filtered by computer ID or license ID and all matching records could be displayed. When I tried that out though I'm having a heck of a time getting the correct items to display.
Just as a basic test i set up a new form and dragged the tables onto it from the Data Sources window using "Details" view for each of them, so that it set up the table adapters and binding sources and navigator for me. I got rid of the auto-added labels + textboxes on the form and added just a couple new textboxes, 1 linked to the licenseID and one to another row i had in that table for productkey...tested it and it moves through the records fine and the correct data shows up in each box to correspond with the other. now though I'd like to add another control to display each of the ComputerIDs that are linked to the particular license being displayed in the other controls via the foreign keys routing through the Installations table, but I'm not having much luck.
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Nov 28, 2010
For example the user has typed a list of names in a text field (1 on each line)
jerry
mark
mark93
ewji84
fjkewo93
the program will auto fill this in the submission form jerry
when it finished the first registration now moves on to the second string:
mark
and so on....
I already made the multiline text boxes and the main functionality of my bot,
all I need now is the program to submit multiple keywords from user input and it should be 1 keyword in the field per submission.
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Sep 17, 2010
I am trying to upate date value as well as time value to a single datetime field.I can update date or time by using today.date or today.time separately.But I don't know how to update both to one field.
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Jul 9, 2009
I have this working for a single field in a text but im trying to add more than one fields data .[code]...
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Jun 9, 2011
i connect database with vb.net and also i receive a single value from my receiver through serial port. now i want to match this single data with one field of database. i have attached my code.
Public Class Form1
Private Sub OPEN_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[Code].....
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Jun 16, 2010
I am saving a text field that may contain a single of double quote.' or "If i use a double quote in my SQL save funciton I can save and use single Quotes. When I use a Single quote I can save Double Quotes. Yet not both.People use both, so I would like to know how I could change the delimiter to something other than a Double Quote for my text saves
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