.net - Create A Generic IsEmpty Extension - Output Is "False"?
Jul 21, 2011
I'm trying to create a generic IsEmpty extension but am having problems specifically with dictionaries: The functions I have created:
<Extension()> Function IsEmpty(null As DBNull) As Boolean
Return True
End Function[code].....
For my purposes, booleans and numerics are never "empty".The problem is that dictionaries are using the generic (Of T)(val As T) function instead of the (collection As ICollection) function.
i.e.
Dim dict As New Dictionary(Of String,String)
Response.Write(dict.IsEmpty)
output is "False"
I tried using (Of K,V)(collection As ICollection(Of KeyValuePair(Of K,V))) to no avail.What am I doing wrong?
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May 30, 2012
After looking at this thread.>>
How to randomize the alphabet I have decided to make it into an extension method for a String and a List.
Note: Please see the following post if you are still using VB.Net 2002, 2003 or 2005
this code is for use with 2008 and later versions of VB.Net
String.Mix and also List.Mix I was trying to write a generic extension method for every Enumerable(Of T)
I settled on just doing it for a STRING
[Code]...
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May 14, 2012
I wrote the following generic LINQ extension for calculating weighted average in Visual Basic 2010:
<Extension()>
Function WeightedAverage(Of T)(ByVal source As IEnumerable(Of T),
ByVal selectorValue As Func(Of T, Integer),
ByVal selectorWeight As Func(Of T, Integer)) As Double
Dim weightedValueSum As Double
Dim weightSum As Integer
[Code] .....
How can I call this function as an Aggregate function of another LINQ query? I tried it in the following way:
Dim q1 = From jd In oContext.JobDatas
Where jd.Year = 2011
Select jd
Dim q2 = Aggregate num In q1 Into WeightedAverage(num.AvSalary, num.NumPosHolder)
The Visual Basic 2010 editor is telling me that the second query (q2) of the following code is not valid statement. On the comma between the first an second argument it's saying: ")" required.
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Dec 16, 2010
I have a custom list that inherits Generic.List and it has a method for deselecting all of the members named DeselectAll It has looked like this for a few weeks and has worked fine.
Public Sub DeselectAll()
MyBase.ForEach(Function(p As Publipostable) p.ModeEnvoiChoisi = Nothing)
End Sub
Today, it stopped working ?!? I reverted to an earlier version using delegates and that works fine...
Public Sub DeselectAll()
MyBase.ForEach(AddressOf DeselectModeEnvoi)
End Sub
[code]....
Edit: Stopped Working meaning it no longer sets the property p.ModeEnvoiChoisi to Nothing on each item in the list. The DeselectAll method gets called, but all the items retain their previous values...
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Sep 16, 2010
Write an overload for every numeric type or if possible constrain a generic extension method to just numeric types.
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Nov 14, 2011
I'm working against a SQL Server database that regularly has DateTime columns that can be null. I'm using LINQ to SQL to connect my WinForms (VB.NET) program to the data. I've extended some of the LINQ objects and added a couple of Nullable(Of DateTime) properties. Basically, I'm calculating whether a particular value exists. The value is a DateTime. If it doesn't exist, I want to create a Nullable(Of DateTime) object (structure, whatever) with the HasValue property set to False.
[Code]....
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Dec 22, 2009
I have this one line property
Public ReadOnly Property DateToUniversal(ByVal dt As Nullable(Of Date)) As String
Get
Return If(dt.HasValue, dt.Value.ToString("u").Substring(0, 10), "")
[code].....
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Dec 4, 2011
1. my program to be the default program for this extension2. when I open the file, I want it to make specific things in the program window3. the things that the file did, I want to be remembered next time I open the program.I want my program to have a better look, so I decided to make Theme Packs for it, and post them on program's website. That's why I want a code for all these things.
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Sep 7, 2011
I have a profile program, were you enter in your personal data such as name, address, phone, company, website, ect, then when you save it, it saves to a file extension like *.pdt, then I can open the file with the extension *.pdt, and all the text fields saved in the *.pdt appear in there correct text fields.
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Jul 24, 2011
I like to create an extension method to Image.FromStream Public Shared Function FromStream(ByVal stream As System.IO.Stream) As System.Drawing.Image
With possibility to cancel processing like Public Shared Function FromStream(ByVal stream As System.IO.Stream, ByVal CloseTask As ManualResetEvent) As System.Drawing.Image
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Jul 1, 2009
I found out how to create file extensions on my PC and I want to open my program with the file extension, but how would I be able to load the text in the file extension into a textbox on my form if that's what the extension is for? And another question, how could I make a file extension that would act like a folder? Like store images and sound files and things like that.
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Dec 30, 2011
I have a question related with VB.Net Code. I see that the DataTable we can use: DataTable(0)'This return a DataRow with the selected index In the intellisense I see that this functionality can achieve with a extension... but, If I create a extension, always I need refer the Extension before to use it
[Code]...
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Nov 18, 2009
I don't really know how to use compression in VB.net, so I was wondering if someone could explain it to me. I'm also wondering if it is possible to create a compressed file with your own extension.
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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 8, 2009
I'd like to do something like this:
Private _myCollection As IList(Of T)
Public Property MyProperty(Of T)() as IList(Of T)
Get
[Code]....
Basically, I want to have a collection of items that may be of any type. Then, I'll be able to do something like this:
Dim myPropertyValue as <the type of some value>
if (MyProperty.Contains(<some value>))
myPropertyValue = CType(MyProperty(<some value>), <the type of some value>)
How can I do this? Or is there a better way than using a generic type?
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Apr 28, 2010
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()
[Code]...
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Apr 1, 2009
I am attempting to create a generic function that the students in my introductory VB .NET course can use to search a single dimension array of a structure.[code]...
My question is: Is there a way to reference the individual structure fields in the array from inside the function? I was trying to make it generic so that the student could simply pass their array into the function - their structure may be named differently than mine and the field names may be different.
I suspect there are other ways to deal with this situation, but I was trying to keep it to just a simple single-dimension array of a structure. I don't think it is possible to do what I want, but I wondered what others thought.
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Apr 19, 2010
I was trying to create a generic Dictionary that implements IXmlSerializable (credit to Charles Feduke).
Here is my trial:
Sub Main()
Dim z As New SerializableDictionary(Of String, String)
z.Add("asdf", "asd")
[Code].....
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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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Mar 19, 2010
How can I create a generic constructor? (ie. BaseClass.FromXml(<param>). I'm not sure how to describe this but I'm trying to create a base class that contains a shared (factory) function called FromXml. I want this function to instantiate an object of the proper type and then fill it via an XmlDocument.
For example, let's say I have something like this: [Code]
I'd like to be able to do something like this:
Dim myObject As CustomObject = CustomObject.FromXml(source)
Is this possible?
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Jul 9, 2009
I'm trying to create a generic ListView user control that can be used over and over again in different projects. I've got all the basics done but I want to be able to act on click events in the from not the user control. In other words if someone right clicks on the listview, for example, I want the form to know it and be able to act on it.
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Feb 14, 2011
say I have two POCOs I'm using in EF code first
Public class C1
property F1 as integer
End Class
Public class C2
property F2 as String
End Class
I want to have a function that will create a list either of C1 or C2, to be used in some generic operation, such that
[Code]...
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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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Dec 3, 2009
Why would I use an extension method instead of just creating non-extension sub or function?
For ex, I could have an extension function called IsNullOrEmptyOrAllSpaces on String, which does a check as its name implies. Or I can write a stand alone function that does the same thing. Other than having the extension show up in Intellisense, is there any advantage? Is a call to the extension quicker/more efficient than a call to a regular function?
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Oct 20, 2009
I'm sort of repeating the same steps. There's got to be a way to shorten it.I was able to shorten it before by making a generic function to create the radio buttons.This is the before the rewrite
Public Sub LoadPanels(ByVal tblClient As DataTable)
Dim count As Integer = 20
Dim tooltip As New ToolTip
Dim countName As Integer = 0
[Code]...
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Sep 17, 2008
I am trying to create bitmap with my text and transformation. I am sure that there is no error in my code. Because this code is worked previously. Here is my code.
[Code]...
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Mar 16, 2010
Here is my code, I cannot produce the output in the lstresults.Text box
Public Class Expense_Report
Const expenseDivide As Double = 50
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
[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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Sep 22, 2011
I'm a really new programmer, teaching myself VB .net
Basically I need user input text from fields in a panel assembled and some parts formatted ( basically italic) and displayed in text box. Really the same as MS Word dose for citation references, then it displays the input correctly.[code]...
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Aug 9, 2011
I would like to be able to create a function where I can change the probability of a number being outputtedI am creating (Well have created) a slot machine game but the outputs are completely random and I would like to change the odds. Is this possible and if so could someone show me or direct me in what I should do to create this function.
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