In the following
For Each <reference> IN <expression>is <expression> evaluated for each iteration of the loop? Specifically, if <expression> is costly to evaluate, would it be wise to evaluate it once before the For Each statement and keep the result in a local variable to use in the For Each statement?
Is there a way to change when an expression in a datacolumn is evaluated?
I'm trying to make a simple total function which sums the values of a particular column in a data grid. Normally the expression is evaluated when I leave from the datagridview, but I wish it to be evaluated when the row is changed.
re: Access of shared member constant member enum member or nested type through an instance qualifying expression may not be evaluated I understand that this warning means that you should not reference a shared member via an instance. However, in my test case Test2.t.x("3"), I don't understand why it thinks I'm using an instance, since t is also a shared member. Also, note Test3. See what happens when you change declaration of GetObject() As Object to As Test3. I think I understand the behavior (not eval'd until runtime)
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warinng message :- Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated.
syntax: lblMessage.ForeColor = Me.f_Color.FromArgb(ds.Tables("Events").Rows(MNo).Item("Color"))
I use .Net 2.0 on this one and i have a warning , i noticed that it runs over a line , here's the code:
Dim i = 0, y = 10
For i = 1 To 5
y = y + 100
Dim pic2 As New PictureBox
[code]....
'Warning 1 Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated.
I have a class with a static list of keys, and I have a static method called Remove() that removes a key from that list.Now what I understand from the contracts post conditions is that as the programmer of the class, I guarantee that the current public method does something specific, in this case : removing the element of the list.
Here's what I've written:
private static List<Keys> m_usedKeys; // private list of keys
public static void Remove(Keys _key)
{
[code]....
What I'm trying to "Ensure" here, is that the Remove() method removes the key for real from the list (Yes this might be a trivial example, but I get the error there.)when I write the Contract.Ensures() line, VS2010 gives me the following error :
Error 3 Detected expression statement evaluated for potential side-effect in contracts of method 'LibJungleTimer.KeyBind.Remove(System.Windows.Forms.Keys)'. (Did you mean to put the expression into a Requires, Ensures, or Invariant call?) C:UsersJoelDocumentsProgrammationJTJungleTimerLibJungleTimerKeyBind.cs 51
I think this error says that the expression m_usedKeys.remove(_key); has a potential side-effect. In fact, it has a side-effect, it removes a key from the list!If I try to write something like this instead :
Contract.Assert(!m_usedKeys.Any(x => x == _key));
well it compiles fine.
i changed a class variable to shared so i can access it in all instances of the class, but it caused an error. what is causing this, and how can i fix it?
Private
Shared img As Bitmap
Me
.img = bgImage
how do I overcome it? I have created a class and compiled into .dll This code
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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
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I thought it would be fun if I could write vb.net or c# code at runtime and the interpreter would automatically parse it like python does it, so I made a little program, which would do something similar. Basically it looks like this:
InputArgs = Console.ReadLine()
ParseInput(InputArgs.Split(" "))
Private Sub ParseInput(Args as List(Of String), Optional TempArgs as List(Of String))
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I know it's not a good system, but it show's the basics. So my question is: Is it possible to make vb.net or c# like python - interpreted at runtime?
Quick question, of which the quickest and easiest answer may well be to rearrange related code, but let's see...So I have an If statement (a piece of code which is a part of a full working solution written in C#) rewritten using VB.NET. I am aware the VB.NET IIf(a, b, c) method evaluates both b and a regardless of the trueness of the first evaluation, but this seems to be the case in my standard construct, too:
If (example Is Nothing Or example.Item IsNot compare.Item) Then
'Proceed
End If
[code].....
How can I get the variable My.Application.Info.Version.ToString to populate in the comments section?[code]..
View 2 RepliesI got this Error. below is my code.
GenerateTheList is function.Need help
Private Sub buttGenerate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles buttGenerate.Click
Dim thread1 As New Thread(New ThreadStart(GenerateTheList))
thread1.Start()
End Sub
While looking in the dataset designer for a database table I am doing in visual basic 2008 I found a line for expressions under the property menu for a specific column. I need to know the code that I would put in this expression line so that this column adds up the numbers I input into three other columns and displays that number in the column. I need it to automatically calculate this for each row in the database table.
View 13 RepliesI am trying to write following expression on a datacolumn. But it results in error:Replicate('*', nLevel) + NameWhere: Replicate() is a user defined function (in a module). nLevel and Name are two other columns in same data table.
View 3 RepliesI am using Flee to build a formula builder. It works great but the only problem I'm facing is that Flee doesn't understand Generic Methods I guess. I have a function called IIf declared in the expression context I'm using. [code]How can I work around this. I mean cannot , in sense, write all possible overloads of the function of all .net primitive types. What approach should I take.
View 1 RepliesI have a page to which i send some variables with the GET method. In my VB back-end i get those variables using Page.Request.QueryString("<name>")If i then use the IsNumeric method to make shure it is an numeric string i get True back as value.
When i then try to transform the string to an Integer using val, cìnt, Integer.Parse or cType I get an error saying that my string could not be converted to a integer.So i made an error page which gives me all the info i need to deal with the problem (view below) Exception Message: Conversion from string "" to type 'Integer' is not valid.
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IsNumeric confirms that it is a numeric string and that it should be convertable to an Integer. So why won't it work. I don't think that my code should provide any extra information because it only gets the querystrings, uses IsNumeric and then tries to convert them.
I recently learned of the IIF(A,B,C) function. I'm a long time VB/VB.NET Coder who recently spent a lot of time coming up to speed in SQL coding. One (obvious) common thing to do in SQL is something like the following:
select (case where @var = 0 then MyTable.Val1 else MyTable.Val2 end) from MyTable
IIF(A,B,C) will allow me to do this in VB.NET... all on one line.
However, I have read that both B and C are evaluated no matter what A evaluates to.
I can think of some obvious situations where this is a bad thing such as:
Dim X as integer = IIF(SomeBoolean = true, ExpensiveFunction1(), ExpensiveFunction2())
As I will be including this in my repertoire, are there any more subtle situations where I may get myself into trouble using IIF? It's a pretty big departure in some situations from using the old fashioned:
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From this code
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If I put New Action(AddressOf PrivateMesage), then I get the following error: Bounds can be specified only for the top-level array when initializing an array of arrays. on the following code
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I must convert string data from a CNC that is arithmetic expression to a number that I can use in a VB application that I wrote. The following is what I get out of the cnc. [18722*65536+19377]/67108864. I need to evaluate this expression in my VB ap. The format of the string is not always the same as what I have illustrated.
View 2 RepliesI am calling this function when a button is CLICKED and received the error; The name "The" is not permitted in this context. Valid expression are constants, constants expression, and (in some contexts) variables. Column names are not permitted. Unclosed quotation mark after the character string 'True)'.
The function is as follows;
Private Sub Save()
Dim conn As SqlConnection = GetDbConnection()
Dim query As String
Dim cmd As New SqlCommand
I would like to know the equivalent expresion in VB for this C# expression: Container.TotalRowCount > 0 ? Math.Ceiling(((double)(Container.StartRowIndex + Container.MaximumRows) / Container.MaximumRows)) : 0
View 3 Repliesi have a string similar to this one:
Hi, <<
ame>> <<surname>>, this is an example << est>>.
I what a regex that match and split this string in:
"Hi, "
<<
ame>>
" "
[code]....
I tried this one: (<<*.*?>>)|(>>*.*?<<), but doesn't work.
What is the vb.net expression of this c# expression ?
Frame.GetController<ShowNavigationItemController>().CustomShowNavigationItem += new EventHandler<CustomShowNavigationItemEventArgs>(WindowController1_CustomShowNavigationItem);
I'm not sure if this is possible but I would like to associate a class name reference to a shared member method / property / variable. Consider:
Public Class UserParameters
Public Shared Reference As Object
Public Shared Function GetReference() As Object
[Code]....
In another part of the program I would like to simply call UserParameters and have it return Reference either by aliasing GetReference or the variable directly.
I am trying to emulate the Application, Request, or Session variable:
Session(0) = Session.Item(0)
I am dumb founded at this statement....maybe its just too many hours/days of doing C# to VB.Net conversion but i am drawing a blank on this conversion.
List<string> sColors = new List<string>(this.CustomPaletteValues.Split(','));
try {
List<Color> colors = sColors.ConvertAll<Color>(s => (Color)(new ColorConverter().ConvertFromString(s)));
What i have so far:
Dim colors As List(Of Color) = sColors.ConvertAll(Of Color)(....)
As you can see its the content of the lambda that i am hitting a brick wall with.
I saw an example of using Expression Builders, and creating your own Custom Expression Builder Classes here: [Url] However, I fail to see the value in using this approach. It doesn't seem much easier than programmatically setting values in your code behind. As far as I can tell, the only thing you can do with them is set properties. Maybe they would be useful for setting defaults on certain controls? Can anyone shed light on where this ASP.NET feature becomes powerful?
View 4 RepliesThe code you posted while similar to VB6 has method and syntax that is very similar to Crystal Reports Scripting Language
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i didn't want to trust this one to any number of online conversion websites that I often use.I don't need to convert the declarations, just the expression '(byte)((flen & 0xff00) >> 8)'in
byte[] sendFrameData = new byte[280
ushort flen
sendFrameData[7] = (byte)((flen & 0xff00) >> 8);
'I am having trouble with the line "senda = suba(sendaobj, EventArgs.Empty)". [code]...
View 12 Replies