IDE :: Crash VS2010 IDE By Mixing Lambda Expressions With SyncLock?
Jun 30, 2011
Can someone who is using a 64 bit machine help me pintpoint this crash to either the VS2010 IDE itself or one of the plugins I have installed?
It's the code fragment below. When I copy & paste it into the Main() function of a new VB.Net console app on my Win7 64 bit machine, the VS IDE crashes and dies onthe spot, every time I try it.
Doing exactly the same on a 32 bit XP machine, nothing abnormal happens.
The 64 bit machine does have some IDE plug-ins installed, the biggest of which is DevExpress (the free version), so i think either one of those or the fact that the IDE is running on 64 bit must be the culprit.
This is the code. The static variable can also be made a module-level variable, with the same result.
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Nov 11, 2009
I see lambda expressions have become a very useful tool at some points in the language. I've been using them a lot and most of the time they fit really nice and make the code shorter and perhaps clearer.
Now.. I've seen some , I would say excessive use of them. Some people like them so much that try to use them everywhere they can.. Some times the C# code looks like a functional language. Other factors against are the cost using reflection by lambda and that not friendly to debugging.I would like to hear opinions about how good and how code clear it is to use more or less the lambda expressions. (this is not the better example, but let's say it was the trigger)I was writing the following code. The use of the delegate { return null; } helps me avoid having to ask if the event is null or not every time I have to use it.
public delegate ContactCellInfo.Guest AddGuest();
public event AddGuest GuestRequest = delegate { return null;}
Im using resharper and the wise resharper( even it some times literaly eats the memory) made me the following suggestion
public delegate ContactCellInfo.Guest AddGuest();
public event AddGuest GuestRequest = () => null;
At my point of view the code using the delegate looks clearer. I am not against the Lamdba expression just would like to hear some advices on how and when to use them.
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Jan 20, 2010
Functionally, is there any difference (apart from syntax onbviously) between lambda expressions in C# and VB.Net?EDIT: following up on CraigTP's answer: any references to the situation in .Net 4?EDIT: I'm asking because I'm used to C#, but for a next project the customer asks VB.Net. We're not a priori against that. We realize that most language constructs are supported in both languages. However, we're particularly fond of the way C# implements lambda expressions. We would like to have an overview of the differences with VB.Net
EDIT: accepted CraigTP's answer for pointing out what I currently consider the most important difference.
So to summarize: VB.Net 9 does not support multiline statements in a lambda expression, and a lambda must always return a value. Both of these issues are addressed in VB.Net 10
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Apr 20, 2012
Async Sub like this: Dim f As Func(Of Task) = Async Sub() End Sub Produces compiler error: error BC36670: Nested sub does not have a signature that is compatible with delegate 'System.Func(Of System.Threading.Tasks.Task)'.Equivalent C# code compiles fine:
Func<Task> f = async () => { };Rewriting Async Sub into Async Function make code works.
Why does Async Sub() is not convertible to delegate types with return value of type Task?
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Jul 4, 2010
how to convert this code to VB.net, can anybody help?
public static readonly DependencyProperty CommandProperty =
DependencyProperty.RegisterAttached(
"Command",
[code]...
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Feb 3, 2012
I have a List(of T) where T has a property that is a list of checkboxes, what I need is a Lambda expression that will count all the checked checkboxes in the list. I tried with:
[Code]...
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Jul 19, 2011
I just came across a bug in NHibernate which happens to already be raised: [url] I'm not sure if this applies to anything else other than enums but when using a Lambda from VB, it looks different to the same Lambda from C#.
C#:
Where(x => x.Status == EmployeeStatus.Active)
VB
Where(Function(x) x.Status = EmployeeStatus.Active)
They are the same as far as I'm aware? (My VB isn't great) If I put a break point on the same line of code, where the above code is passed into. In C# I get: On the same line when VB version is passed in, I get: Is this something I'm doing wrong? Is the result's the same, just displayed different between C#/VB?
Edit: Ok so they are displayed different, but they can't be the same because NHibernate cannot handle it. The C# version is handled perfectly fine by NHibernate, the VB version resolves in the following exception being thrown: [Code]
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Jul 25, 2011
I have an issue with building a project using the MSBuild (ver 4) from the command line when declaring lambda expression like this:
Private Sub Foo(ByVal s As String)
Dim WL = Sub(str As String)
If Not String.IsNullOrEmpty(str) Then[code]......
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Mar 6, 2009
I'm trying to expand my programming horizons, and LINQ and Lambda Expressions have popped up as some apparently very important topics. As I began reading articles on Lambda Expressions, it appears that Lambda Expressions are built heavily on the concept of Delegates. As I began reading articles on Delegates, it appears that Delegates are built heavily on the concept of callback functions. As I began reading articles on callback functions, .[code]Can anyone out there give me a simple, clear, concise definition of callback functions? Do I need to learn C or C++ to fully understand these concepts? Maybe a better question is: What do I need to know to be able to understand Delegates (they've always somewhat mystified me) and LINQ/Lambda Expressions (I haven't looked into these too much, but they're mystifying, too)?I don't mind doing research, but google searches are giving me way too much information.
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Jul 7, 2010
what are delegates?How are the lambda expressions related to the delegates?
reading the msdn about the delegates is really confusing me ;so i need a start off from here before moving on to the msdn.
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Jul 1, 2011
To streamline code, I increasingly rely on lambda expressions. But I may have hit against the wall in the attempt of removing an event handler set by a lambda expression. This really eludes me. The code below shows two samples: Alt1 uses a plain lambda expression as delegate and works fine: the object size increases as the numeric control varies. However, the drawback is that the handler cannot be removed:
RemoveHandler Me.upDnScale.ValueChanged, Sub(sender As Object, e As Object) ScaleObject1(sender, e, objTgt)
According to this MSDN article, a variable should be used to set/remove lambda based handlers. Alt2 shows a couple of attempts, but none works.
[Code]...
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Feb 22, 2010
I have a type lets call it "MyType". I have a List(Of MyType). Here is what i'm doing: MyList.Sum(Function(x) x.MyFieldToTotal) "MyFieldToTotal" is a decimal. For the life of me i can't figure out why x above is an object rather than a type of "MyType". Shouldn't Type Inferencing be working in this case? Even in intellisense i get "selector as System.Func(Of MyType) as Decimal"
[Code]...
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May 21, 2012
Currently I am searching through my list to find Customers that match on Address.
I need to match on both address and city. How do I rewrite my lambda Expression to match both criteria?
CustomerList.FindAll(Function(c) c.Address = addressToMatch)
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Jul 2, 2011
How to remove a handler set up by a lambda expression? According to this MSDN article, lambda expression should be assigned to variables which should be used to define handler operators. So far, I have used lambda expessions w/o variables.
For instance, the following works:
Private Sub ScaleObjectInit1(ByVal objSrc As NumericUpDown, ByVal objTgt As FrameworkElement) ...
AddHandler Me.upDnScale.ValueChanged, Sub (sender As Object, e As Object) ScaleObject1 (sender, e, objTgt)
End Sub
Private Sub ScaleObject1(ByVal sender As Object, ByVal e As Object, ByVal objTgt As FrameworkElement)
[Code] .....
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Nov 16, 2009
I'm still trying to get my head around the whole "Lambda Expressions" thing.
Can anyone here give me an example ordering by multiple columns using VB.Net and Linq-to-SQL using a lambda expression?
Here is my existing code, which returns an ordered list using a single-column to order the results:
Return _dbContext.WebCategories.OrderBy(Function(c As WebCategory) c.DisplayOrder).ToList
Note: The WebCategory object has a child WebPage object (based on a foreign key). I'd like to order by WebPage.DisplayOrder first, then by WebCategory.DisplayOrder.
I tried chaining the order bys, like below, and though it compiled and ran, it didn't seem to return the data in the order I wanted.
Return _dbContext.WebCategories.OrderBy(Function(c As WebCategory) c.DisplayOrder).OrderBy(Function(c As WebCategory) c.WebPage.DisplayOrder).ToList
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Mar 16, 2009
I have an untyped dataset returned from my WebService. The user wants to dynamically construct a query referencing tables and columns and specifying values to test for.I have looked at Lambda Expressions and the Expressions.Expression Namespace. I think these provide the answer I'm looking for, but I'm not certain how to go about contructing the linq expressions to extract the datarows I'm looking for.
I plan on limiting the result to one datatable that the query will result in and i"ll provide the joins from the user's constructs.For a simple example I have a DataTable with (n) rows called "Table", and in it there is a computed column called "b_IsActive" that has the expression "Convert(IsActive, 'System.Boolean')". The user wants to retrieve all rows in "Table" where field "b_IsActive" is true.
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May 20, 2009
I'm looking for an advanced level VB.NET book which covers LINQ and Lambda Expressions.Generally I read C# .NET books due to lack of good VB.NET books when it comes to generic .NET Framework related subjects. However Lambda and LINQ is quite different in C# and VB.NET I'm looking for an advanced level VB.NET book on this subjec
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Jun 29, 2010
While reading an article by Deborah Kurata "Getting ready for VB10" under the section "Better Support for Lambda" she mentions using multi-line Lamba for debugging. So I tried it out on a class and worked just as she described (see figure 1). Now I am wondering if this can be done in regards to ForEach with a Dictionary as shown in figure 2. I am asking as when attempting to mimic the ForEach in figure 1 I get a message indicating there is no signature suitable for doing the multi-line Lambda statement for a ForEach
Private Sub Example()
Dim Taxpayers = New List(Of Taxpayer) From
{New Taxpayer With {
[code].....
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Jun 21, 2011
Im hearing about this, can someone explain it to me or please show some basic code of Lambda with explanation.
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Dec 14, 2009
Is it possible to shorten the following function to a lambda expression?Or (to do the trick by myself) what is the best and most understandable for beginners tutorial for lambda in vb.net?[code]
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Aug 14, 2009
Can you mix vb and c# files in the same project for a class library? Is there some setting that makes it possible? I tried and none of the intellisense works quite right, although the background compiler seems to handle it well enough (aside from the fact that I, then, had 2 classes in the same namespace with the same name and it didn't complain). We're trying to convert from VB to C# but haven't finished converting all the code. I have some new code I need to write, but didn't really want to make a new project just for it
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Jun 24, 2010
i wanta fileshare i think thats what it called prob not but his my code make it vb 2008 ||...these are two DIFFERENT EXE's
FILESHARE = "@JIOJDOSIAMDOSMAMPCA@"
public class shareReciever
Private sub btn1_click(blah)[code].....
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Jul 23, 2010
I'm using the WndProc To get messages about USB flashdrives connecting and removing from the users computer. It works grand. I also use WMI queries to get the info about the flashdrives. It works as it shouold. The problem is when both of these are in the same solution. I ended up creating an extra .EXE that uses the WMI queries to get the drive info and output the info to a CSV file which my Main will parse. I tries creating a seperate class of each and i also tried to make a DLL that I import to no avail.
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Mar 15, 2009
This is my first post as I don't like to ask questions without making sure I've exhausted all other means. I'm new to VB2008 and programming in general but I'm learning. I want to do several simple tasks. Doing each separately is easy but when I put them together I don't know what to do. For one thing to work all the code must be changed and everything else doesn't work.
1. Plot a graph of data from a DAQ. I can do this by using a Timer1_tick method and displaying the data on the linegraph as long as the timer is turned on. I've decided to stick with this method of acquisition. I want to acquire data for long periods of time (perhaps 3 hours) so a timer is pretty good. No problems here.
2. Apply a filter to remove noise from the plot dynamically as the data comes in so that I get a smooth curve instead of a jagged graph. I know I can do this with for loops if I'm using an array. But how do I do it since I'm using a timer? Here the problem begins.
3. Log every piece of the filtered data that the timer is getting to be exported to a CSV file. I learned how to do this with do loops but not with a timer or array. But I really need to use the timer this time.
4. Acquire statistics for the data like maximum value, minimum value, and average value dynamically as the data changes. I know how to do this with an array of data after all the data is acquired. But How do I do this with a timer while the data is still being collected?
5. Monitor the data coming in to execute an alarm (Or event, like stopping the acquisition) when the data coming in has plateaued and is constant (eg: The voltage I'm monitoring starts to become constant and becomes one constant value) - Ok I don't know anything about this.
6. Execute a mathematical operation on the data that has been acquired (post acquisition) like finding gradients and such. Basically this means "How do I now manipulate the data I have and where is this data stored?"
Here's my starting code that gathers data with a timer. How do I work from here?:
Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As
System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
Timer1.Enabled = False
[code]....
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Mar 29, 2012
My app is basically console based but I need a Form to run in background. Adding a form in the app works but using Form1.Show didn't work, so I used VB.NET Application.Run(New Form1) However, in Form1_Load Me.Hide didn't work. I have no idea why. It works in buttons or other components in the same form.
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Oct 9, 2010
First let me start off by saying that I have dealt with Winsock for MANY years and am attempting to convert my project over from vb6 to VB.Net.This program was made to handle up to 70 connections at a time and constantly sending data from Server to clients and back.
There is one packet however, that reaches up to be around 177kb when sent. The sockets are set up to sent 1kb at a time.... (No other packet actually uses the whole kb). It seems that after the server sends this large packet... the client receives the data out of order. After debugging and monitoring I find that it normally happens between 3-4kb. While the first 3 are good and in order.My question is, is there a different system I should use instead of just Sockets (I have had similar problems with TCPClient) and/or can someone maybe link me to a sample project that would not have this error?
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Aug 8, 2010
I am currently writing a VB.net app to control an Integra AV receiver. I have success controlling it via Serial, but it also has a network port for TCP control. I can control it using CommandFusion iPhone app but am now wanting to create a windows app to control it. I have created client/server software that I use to talk from one PC to the which works well. So I am going to use the same client software to talk to the AV receiver. I can connect fine to it, I just haven't quite got the protocol right to actually control it.
[Code]...
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Sep 15, 2010
I was just wondering if mixing SyncLock blocks and Monitor.Enter/Exit statements is dangerous. I know SyncLock uses Monitor and a Try block in the background, but are there any problems with using the two together for thread synchronization?
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May 28, 2012
I am pretty new to multi-threading in general and I would like to know how can I lock a shared integer variable to not be accessed by other threads while it is read/updated by an other thread.When I try do do SyncLock myInteger, I get that error : Error 6 'SyncLock' operand cannot be of type 'Integer' because 'Integer' is not a reference type.
Here a simplified example of what I mean
Private Shared myInteger As Integer
Private Sub MySub()
SyncLock myInteger ' This does not work
' read/write a new value to myInteger
End SyncLock
End Sub
MySub is called by multiple instances of the class, and running in multiple threads?
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Mar 25, 2011
Is there simple way to SyncLock an object that can be null? And before you ask for it, yes, I know that it isn't logical to perform a SyncLock on a null variable. However, that would simplify my code because right now, I have no choice but to perform a null check all over the place before calling a SyncLock.
[Code]...
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