Using An Enumerator To Parse A Collection?
Feb 13, 2009
If I am using an enumerator to parse a collection such as
Code:
''' <summary>
''' Checks to see if Node1 is a direct child of Node2
''' </summary>
[Code].....
The object comparison of Enumerator.Current and Node1 passes an option strict check, but should I for readability and or for any other reason cast it to the correct type? I know their object references will ultimately be checked the same way, but is it generaly bad form to assume this?
Second question. I recently came across the use of the Enumerator v/s a For/Each loop through the collection, does anyone know the pros/cons of the use of either in specifi situations. Where one is favorible to the other or where they should or should not be used?
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Apr 25, 2009
For
Each
Item As
DataRowView In
lbOrdersNeedToBeVoided.Items
[code]....
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Jul 20, 2010
I tried utilizing a collections Enumerator inside of a USING block to take care of the Enumerator.dispose call for me, however, I'm getting NullReferenceExceptions when trying to access the Enumerator.Current property after doing a MoveNext.
[Code]...
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May 21, 2009
I have these variables as shown below. The FadeMode is assigned on of the 3 integer values. I would like it to work like an enumerator, so that when I working with the code editor, IntelliSense offers a choice of the 3 possible values. Like x = Fademode.FadeOut
Const FadeIn As Integer = 0
Const FadeOut As Integer = 1
Const FadePause As Integer = 2
Friend FadeMode As Integer = FadeIn
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Jul 17, 2010
I am looking for a way to read an XML file at run time and construct an Enumerator from it. I got the reading and writing all working, it's just getting all the strings to create an enumerator that's the tricky part. I could get them into a collection of strings or maybe a dictionary, but not sure how to go about converting from these into an enumerator. The goal of this is to allow users to add and delete items from the underlying enumerators and eliminate writing hard coded enumerators. My idea is to allow users to extend the program without coding. This is a Winform vb app thats not using any database but just XML files to store and retrieve things.
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Dec 2, 2011
It looks like passing a list's enumerator to a function "byval" is quite different than passing it "byref". Essentially, regular "byval" passing will NOT change the caller's "enumerator.Current value", even if the function advances the enumerator. I was wondering if anyone knows why this is the case? Is an enumerator a primitive like an integer, without an object reference, and hence changes to it don't get reflected in the caller?This function is byval, and gets stuck in an infinite loop, spitting out "1" message boxes, because the enumerator's "current" never advances past 5.[code]The difference between the two functions is only whether the listFirstItem__ function accepts a byval or a byref enumerator.
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Aug 15, 2011
According to the language specification guide for VB.NET Section 10.9.3. The enumerator expression in a for each loop is copied over into memory. If I have a list of 10000 objects that list will be in memory twice for the code below?
dim myList as new list(of bobs)
'put 10000 bobs in my list
for each x In myList
'do something
next
If I were generating the list from a linqQuery or some other such query it would make sense to generate that list at the for each loop statement thus not having the list in memory twice for example.
for each x in myList.where(function(x) x.name = Y)
'do something
next
If the LINQ query is unreadable on the for each loop, do I forgo readability and just put it on the for each loop declaration line? Should I declare the list in its own variable and just bite the bullet and have the list exist twice in memory?
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Dec 30, 2009
if a call to For Each starts by calling the Enumerator's MoveNext, then Current, then MoveNext, then Current, and so on until MoveNext returns a False then it exits, am i right to say that the Reset is never called?initially i thought that Reset would be called when MoveNext returns False, i tried this (a msgbox would come if it was ever called but i got no msgbox at all)
[code]...
if that's the case, what exactly is the use of the reset in an ienumerator, and is it ok to leave it empty, as such
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Jun 8, 2012
I just want to parse simple expressions like IIF(FVAL(PFC) = TRUE, (IIF((ORGVAL(BAS, "2012/12/31") + ORGVAL(DA)) < 6500, (FVAL(BAS) + FVAL(DA)) * 12%, 780)), 0)`After parsing this I should be able to know what functions contains what parameters.
[Code]...
I'm stuck with .Net Framework 2.0, so no Linq or lambda expression goodies for me. Also I want to include the code in my custom library and not just reference it. Can anyone point me to some good library or code.
I just need to parse and not evaluate the expression and find what tokens are in use. After finding the tokens I need to change the expression string before parsing, like if the function ORGVAL is used then the parameter passed has has to be prefixed by an underscore. Like ORGVAL(BAS) will transform to ORGVAL(_BAS). Some functions can have tow parameters like ORGVAL(BAS, "2012/12/31") and this will transform to ORGVAL(_BAS, "2012/12/31")
NOTE: IF THERE ARE OTHER WAYS OF DOING IT PLEASE LET ME KNOW. I WOULD LOVE TO AVOID A PARSER AND LEXER.
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Sep 20, 2011
Is that possible to get current Enumerator (...or iterator? Don't know which tern is the correct one) in a LINQ query ? For example, I try to create a XML output (via LINQ to XML) of all currently loaded assemblies. [code] is it possible to somehow get current "index" (counter?) from LINQ's Selects? I would like to use it in XML. [code]
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Jan 15, 2010
Is it good practice to store sub-collections of item X inside a parent collection of item X for caching 'filter-queries' which are performed on the parent collection? (They won't be used together (as in color AND type).) Or is it also ok to just Loop over the collection and return the correct entities in a temporary collection?
[Code]...
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Sep 7, 2011
I have the following classes:
Product, Service and OrderItem
Product and Service must inherit OrderItem. So basically I want to store OrderItem object in my shopping cart and these object are store in a list.
Public MustInherit Class OrderItem
Private m_enuItemType As TypeOfItem = TypeOfItem.None
Private m_strUserID As Integer[code].....
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Feb 8, 2010
I have been researching for a couple of days now and to no avail. Does Anyone know how to make a custom collection that take advantage of the collection editor? I would like to be able to have 3 Color Values, 1 Boolean and 1 String.
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Jul 25, 2011
I'm trying to support Basic.NET on my framework so I'm trying to convert C# 4 code to Basic.NET 10. Microsoft is committed to "co-evolve" these two but I'm having a problem with collection initialization... I found that I can initialize a collection much like in C#:
[Code]...
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Apr 15, 2009
I've got the following ADO.NET Entity Framework Entity Data Model:I want to find all the Policyholders with both a Service of a given Id and also a Keyword of a given Status.
This LINQ Does Not Work:
Dim ServicesId As Integer = ...
Dim KeywordStatus As Integer = ...
Dim FoundPolicyholders = From p As Policyholder In db.PolicyholderSet.Include("Keywords").Include("Services") _
Where p.Services.Id = ServicesId _
And p.Keywords.Status = KeywordStatus _
Select p
The Where clause cannot search the p.Services and p.Keywords EntityCollections in that way.
[Code]...
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Apr 6, 2012
currently in my application I have a Global Collection that is a Collection of Collections.Currently I am trying to add items/ elements to one of the child collections of the Global Collection but I am unable to use the collections methods of the child.When I assign a variable to the child collection and return the collection it is just an object with the collection inside.
Ex:
Dim GlobalCollection as New Collection
Dim ChildCollection1 as New Collection
Dim tempCurrentCollection[code]......
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Dec 17, 2009
I've been working with a CMS called InsiteCreations 2008. I'm running into an error I just can't wrap my head around. I would even be willing to compensate anyone a small amount over paypal, for a solution. The error is rare in occurance, and appears when clicking about 3-4% of links to other pages within our CMS.The full code page is quite large, but there seems to be only one function associated with the error. The error also only appears when not logged into the CMS. If logged into the CMS, clicking the link simply displays the page as normal. I have already checked permissions on the page from the CMS admin console, and it is public.
The error message is as follows:
Server Error in '/' Application.Collection index must be in the range 1 to the size of the collection.
Description:
An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
[code]....
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Apr 15, 2011
search the collection of a collection in my LINQ Where clause?
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Apr 14, 2011
Take the following scenario:
Public Class Store
Public Overridable Property Areas As List(Of Area)
End Class
Public Class Area
[code]....
What's the quickest way to get a total count of shelves for a store? I.e. for a store I get the total count of areas by using Areas.Count Or will I need to loop through each area and tally the count of shelves?
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Mar 25, 2011
I have an ASP.NET app with lots of textboxes all over the page that need updating at various points through program execution. These textboxes actually belong to a certain class, so for easy updating I thought I could create a Dictionary(Of string, object) and add the control.ID and the control to it and then for updating do something like this:
[Code]...
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Jun 26, 2012
I need to convert a VB Collection to a modern one, like Dictionary or Hashtable. For my approach, I need the Collection's KEYS. Googling tells me that it's impossible. Re-writing the entire application using new collections is not an option as the application is really old and large (converted from VB6 to VB.Net).Using the old Collection also is not good - as there are new components in development.Converting a - for example - Hashtable to Collection works:
using VBCollection = Microsoft.VisualBasic.Collection;
public static VBCollection ToVBCollection(this Hashtable table)
{
[code]....
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Aug 12, 2009
I have a collection of lines and as i loop through through the collection, i need to see if it aleady contains a certain line; however, the contains method wants a string and i have stored lines, so how can i use this method to see if my line is already in the collection so i don't place it in there twice?
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Aug 4, 2011
Is it possible to print to a collection(), then prompt to print the collection?
[Code]....
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Jul 29, 2010
I'm still relatively new to parsing xml documents into SQL. I am trying to parse one node out of an xml document.[code]...
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Sep 29, 2009
What's the easiest way in VB.NET to parse this XML? Here's an example of the full source:View Source XML I believe that the XML can be read directly into a class structure that matches the XML's structure.Let's take a bit of the XML from the above example,
<?xml version="1.0" encoding="UTF-8" ?>
- <kml xmlns="http://earth.google.com/kml/2.0">
- <Response>
[code]....
How do I handle nested collections, for example, the Placemark collection in this example?
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Sep 17, 2011
I have an app that the user selects information and it writes to an XML file. The user can increase and decrease the information in the XML file so it is dynamic. The other app reads the xml file and uses it to complete tasks. Since the XML is dynamic my code needs to account for that. Right now I have only allowed the XML to have up to four values in a certain node, I would like to allow more but I will need to increase the Select Case function.[code]
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May 5, 2011
I am making a change to an existing process. Currently the csv file (which can have embedded "," with the field in quotes), is being passed to my module as a IO.StreamReader, pStreamReader.
[Code]...
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Oct 31, 2010
parsing text that i have loaded in to my textbox Using ofd1 As New OpenFileDialog ofd1.InitialDirectory = "F:"
If ofd1.ShowDialog = DialogResult.OK Then RichTextBox2.Text = My.Computer.FileSystem.ReadAllText(ofd1.FileName)
End If
End Using
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Apr 6, 2010
create a function that parses the input "4+7-4/4*4=" from instr into an array named tokens(1000), as string, and returns the number of arrays, or perhaps a negative number if there is an error in the input.
Dim tokens(1000) As String
Private Sub btnGo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGo.Click
[code].....
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Nov 1, 2009
I have XML data like this:[code]I would like to return the name of the places. How may I extract this data using Visual Basic?
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