VS 2010 Struggling With OrderBy Lambda Expression?
Aug 24, 2011
I'm getting my feet wet with Lambda expressions and it's rather overwhelming.I have a UserPrincipal object called SelectedUser. I wish to get a sorted list of the user's groups This is what I have so far but when I include that code my application's form flashes a few times and closes! Also, what is the significance of the "r" in the "Return From r" statement?
Dim SortedGroups As PrincipalSearchResult(Of Principal) = GetSortedGroups(Me.SelectedUser.GetGroups())
Private Function GetSortedGroups(ByVal psp As PrincipalSearchResult(Of Principal)) As PrincipalSearchResult(Of Principal)
Return From r In psp.OrderBy(Function(t) t.Name)
End Function
I've got the following to sort entities by their job position. The desired order ist defined in another array. In C# this code works:[code]However I will have to convert this to VB.net. I read the equivalent would be something like the following:[code]This does not compile, gives me "Expression expected" right after the Function(x). What am I doing wrong?
I've been wondering about lambda expressions for a while now.Consider the following code..[code]But in the lambda expression I have access to all Sub Main's variables.
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
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
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.
In looking at Fuzzy Date Time Picker Control in C# .NET? Piotr Czaapla's answer to that question is exactly what I need. unfortunately, I'm a VB.NET guy and I'm not that familiar with lambda expresions, so my attempts to convert the code have resulted in hours of misplaced parenthesis and banging my head with a brick.
Any chance some bi-lingual wizard could convert the C# code to VB.net for me?
I will probably sound like a bad developer here, but I am attempting to convert some code from the following page from C# to VB.NET:The code I am having trouble converting is from Step 4 of "Joining a Multicast Group" on the page, and here is the code with the comment lines removed:
private void Join() { _receiveBuffer = new byte[MAX_MESSAGE_SIZE];
Public Function GetFunc(Of TSource, TResult) _ selector As Expression(Of Func(Of TSource, TResult)) _ As Func(Of TSource, TResult)
[code]....
UPDATE:I have the following issue, it's a part of a function:
Dim obj As Object = value For Each exp In expressions If obj Is Nothing Then Return [default]
[code]....
Exception Details:
ArgumentException:Object of type 'System.Linq.Expressions.Expression`1 [System.Func`3[System.Char,System.Char,System.Char]]'cannot be converted to type 'System.Func`3[System.Char,System.Char,System.Char]'.
If been try to convert some code I have from VB.net to C# but I just cannot get it working!first is the vb code I'm only interested in the line that has the Lambda Expression for the C#[code]......
I know in VB Lambda expressions must return a value and can only have one statement. But in my case I just need to execute a Sub that does not return a value. Is there a way to trick it by somehow returning a dummy value yet still call my Sub? If possible what would the syntax be like?
I am having an issue using the vb equivilant of the MAX lambda expression. at foos.Max(function(x) x.id) when I try to intellisense the property ID VS will not show it. But when i run the example it works. Is there something I am doing which is wrong, an i am just lucky it runs? [Code]
Private Sub InsertItemInCache(Of T)(ByVal item As CachedItem(Of T), ByVal dependency As AggregateCacheDependency, _ ByVal key As String, ByVal updateCallBack As CacheItemUpdateCallback)
I am Creating a Lambda Expression, but it' not getting me the write Out put :
Public Class Form1 Delegate Function GetLastChar(ByVal S As String) As String Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[code]....
I want Send a Name like "Arindam" and its return me "m", the last character.but in messagbox return value shows "fasle" I can't under stand why it's showing "False" instead of "m", the last character.
I am having a generic ListOf-collection holding the self-created User-object, I can filter for users by using lambda-expression like this: Dim reviewers As List(Of User) = users.Where(Function(u) u.DvRoleID = 2).ToList
Instead of using the lambda expression I can also write the function and call it as argument like this: Public Function GetReviewer1(ByVal u As User) As Boolean If u.DvRoleID = 2 Then Return True [Code] .....
Now the question: why can't I create a delegate having the same signature as the GetReviewer1 function and use the delegate as argument inside the where-clause like this: Delegate Function Criteria(ByVal u As User) As Boolean Public Function GetReviewer1(ByVal u As User) As Boolean If u.DvRoleID = 2 Then [Code] ..... The compiler does not accept the crit delegate as argument.
I am trying to see if the controller class name is the name of the controller name passed in. I think my lambda expression is wrong and that is why it isn't working properly. I am passing in the correct controller names, but the export variable is always null.
Public Function CreateController(requestContext As System.Web.Routing.RequestContext, controllerName As String)
In MSDN documentation defination about lambda expression is "A lambda expression is a function or subroutine without a name that can be used wherever a delegate is valid ". Here validity of delegate is necessery only when we are passing lambda expression as an argument to a method.
Where can I find complex LINQ examples made using VB.NET Lambda Expression syntax?During my searches I always found 101 LINQ Samples but they use the other notation and for me is not always clear how to transform that code into a lambda expression.
Should I be concerned about the performance of the Compile method here?[code]...
The reason I want the lambda expression is because I want that function to be able to get all the way through LINQ-to-SQL to be converted to SQL. The reason I want the direct version is because I have other code that I want to validate individual serial numbers before submitting changes. And I fear that GetValidSerialNumbers.Contains(serialNumber) will execute a more-complex-than-necesssary query.
With ASP.NET MVC 1.0, .NET 3.5 and C# you can easily pass a method a lambda expression that will do a "Response.Write" some content when it's executed within the method[code]...
I'm using SharpZipLib to compress files. The library is wrapped in a plugin interface, in a separate DLL. I pass the plugin dll a ByRef parameter to keep track of the compression progress.SharpZipLib, while compressing, will periodically call a delegate sub passed when launching the compression. I can't figure out how to update the ByRef parameter when the delegate is called. If I try to assign the ByRef variable in the body of a lamba expression, I get a 'ByRef' parameter '<parametername>' cannot be used in a lambda expression error.
