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Strongly Typed Key Value Collections within a For Next loopI am writing a windows application using vb.net on the 1.1 framework. We have in the application, some strongly typed collections that have been written as classes that do not inherit from collection base, but use an internal collection, to hold the objects and then implement IEnumerator, see example below, Public Class AttributeCollection Implements IEnumerable Protected intCollection As New Collection Public Overridable Sub Add(ByVal Attr As Attribute) intCollection.Add(Attr, Attr.Name) End Sub Public Sub Remove(ByVal Attr As Attribute) intCollection.Remove(Attr.Name) End Sub Public Sub Remove(ByVal AttrName As String) intCollection.Remove(AttrName) End Sub Public Function Count() As Integer Return intCollection.Count End Function Default ReadOnly Property Item(ByVal AttrName As String) As Attribute Get Return CType(intCollection.Item(AttrName), Attribute) End Get End Property Default ReadOnly Property Item(ByVal index As Integer) As Attribute Get Return CType(intCollection.Item(index), Attribute) End Get End Property Public Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator Return intCollection.GetEnumerator End Function End Class These collection allow us to do a for each loop down the collection, For each attr as Attribute in someAttrCollection .... code Next However, we are having problems with this type of collection so are moving to inheriting our strongly typed collections from collectionbase. However collectionbase does not use Key Value pairs. We have tried inheriting from DictionaryBase, but that then stops all the for next loops from working as the items it returns are dictionary entries, not the internal objects we wish to get. I know if we inherit from DictionaryBase we can change to a For each attr as Attribute in someAttrCollection.Values but there are 10's of thousands of lines of code, and we would prefer not to have to change our for next loops if possible. So the question, how do we create a strongly typed key value pair collection that allows a for next down the created collection returning the objects contained in the value part? How the question is understood. Thanks in advance for any help or advice. Regards, Simon. Hi,
The code is in c# but I think this article will help. http://www.codeproject.com/csharp/hashlistarticle.asp Ken -------------------- Show quoteHide quote "Simon" <s@v.c> wrote in message news:43e9c74c$0$6955$ed2619ec@ptn-nntp-reader02.plus.net... > Hi all, > > I am writing a windows application using vb.net on the 1.1 framework. > > We have in the application, some strongly typed collections that have been > written as classes that do not inherit from collection base, but use an > internal collection, to hold the objects and then implement IEnumerator, > see example below, > > > Public Class AttributeCollection > > Implements IEnumerable > > Protected intCollection As New Collection > > Public Overridable Sub Add(ByVal Attr As Attribute) > intCollection.Add(Attr, Attr.Name) > End Sub > > Public Sub Remove(ByVal Attr As Attribute) > intCollection.Remove(Attr.Name) > End Sub > > Public Sub Remove(ByVal AttrName As String) > intCollection.Remove(AttrName) > End Sub > > Public Function Count() As Integer > Return intCollection.Count > End Function > > Default ReadOnly Property Item(ByVal AttrName As String) As Attribute > Get > Return CType(intCollection.Item(AttrName), Attribute) > End Get > End Property > Default ReadOnly Property Item(ByVal index As Integer) As Attribute > Get > Return CType(intCollection.Item(index), Attribute) > End Get > End Property > > Public Function GetEnumerator() As System.Collections.IEnumerator > Implements System.Collections.IEnumerable.GetEnumerator > Return intCollection.GetEnumerator > End Function > > > End Class > > These collection allow us to do a for each loop down the collection, > > For each attr as Attribute in someAttrCollection > ... code > Next > > However, we are having problems with this type of collection so are moving > to inheriting our strongly typed collections from collectionbase. However > collectionbase does not use Key Value pairs. We have tried inheriting from > DictionaryBase, but that then stops all the for next loops from working as > the items it returns are dictionary entries, not the internal objects we > wish to get. > > I know if we inherit from DictionaryBase we can change to a > For each attr as Attribute in someAttrCollection.Values > > but there are 10's of thousands of lines of code, and we would prefer not > to have to change our for next loops if possible. > > So the question, how do we create a strongly typed key value pair > collection that allows a for next down the created collection returning > the objects contained in the value part? > > How the question is understood. > > Thanks in advance for any help or advice. > Regards, > Simon. > Thanks for the reply Ken,
I have read this article, and it seems to be similar to what we already do with our collections, by implementing interfaces on a base class, and handling the objects in the collection internally, as I have shown in the example, in my first post. The current way we create our collections, similar to the article, is working as we want in the windows app, however we are having problems with these internal type collections in the ASP.NET app that uses the same objects, which we cannot fathom, I have several posts in the ASP.NET newsgroup regarding this. We have converted a few of them to be implicitly inherited from collectionbase, and the problems seem to have abated, although we think it's too soon to say the problems are solved. There are some of these collections that need to be key value type collections, and they are used in loads of places, that we do not want to change the code. So I was kind of hoping there would be a way to inherit from one of the base collections, and retain the key value relationship, but be able to simply For each down the collection, not the collection.values. Regards, Simon. Show quoteHide quote "Ken Tucker [MVP]" <vb***@bellsouth.net> wrote in message news:OPQRpcKLGHA.3492@TK2MSFTNGP09.phx.gbl... > Hi, > > The code is in c# but I think this article will help. > http://www.codeproject.com/csharp/hashlistarticle.asp > > Ken > -------------------- > "Simon" <s@v.c> wrote in message > news:43e9c74c$0$6955$ed2619ec@ptn-nntp-reader02.plus.net... >> Hi all, >> >> I am writing a windows application using vb.net on the 1.1 framework. >> >> We have in the application, some strongly typed collections that have >> been written as classes that do not inherit from collection base, but use >> an internal collection, to hold the objects and then implement >> IEnumerator, see example below, >> >> >> Public Class AttributeCollection >> >> Implements IEnumerable >> >> Protected intCollection As New Collection >> >> Public Overridable Sub Add(ByVal Attr As Attribute) >> intCollection.Add(Attr, Attr.Name) >> End Sub >> >> Public Sub Remove(ByVal Attr As Attribute) >> intCollection.Remove(Attr.Name) >> End Sub >> >> Public Sub Remove(ByVal AttrName As String) >> intCollection.Remove(AttrName) >> End Sub >> >> Public Function Count() As Integer >> Return intCollection.Count >> End Function >> >> Default ReadOnly Property Item(ByVal AttrName As String) As Attribute >> Get >> Return CType(intCollection.Item(AttrName), Attribute) >> End Get >> End Property >> Default ReadOnly Property Item(ByVal index As Integer) As Attribute >> Get >> Return CType(intCollection.Item(index), Attribute) >> End Get >> End Property >> >> Public Function GetEnumerator() As System.Collections.IEnumerator >> Implements System.Collections.IEnumerable.GetEnumerator >> Return intCollection.GetEnumerator >> End Function >> >> >> End Class >> >> These collection allow us to do a for each loop down the collection, >> >> For each attr as Attribute in someAttrCollection >> ... code >> Next >> >> However, we are having problems with this type of collection so are >> moving to inheriting our strongly typed collections from collectionbase. >> However collectionbase does not use Key Value pairs. We have tried >> inheriting from DictionaryBase, but that then stops all the for next >> loops from working as the items it returns are dictionary entries, not >> the internal objects we wish to get. >> >> I know if we inherit from DictionaryBase we can change to a >> For each attr as Attribute in someAttrCollection.Values >> >> but there are 10's of thousands of lines of code, and we would prefer not >> to have to change our for next loops if possible. >> >> So the question, how do we create a strongly typed key value pair >> collection that allows a for next down the created collection returning >> the objects contained in the value part? >> >> How the question is understood. >> >> Thanks in advance for any help or advice. >> Regards, >> Simon. >> > > The guidance (for 1.1) is to inherit from CollectionBase. To do what you
need, you may just need to modify the Item property as follows: Default ReadOnly Property Item(ByVal AttrName As String) As Attribute Get for each child as Attribute in List if Child.ID=AttrName then return Child end if Next 'Nothing found, NOTHING will be returned End Get End Property Jim Wooley Show quoteHide quote "Simon" <s@v.c> wrote in message news:43e9c74c$0$6955$ed2619ec@ptn-nntp-reader02.plus.net... > Hi all, > > I am writing a windows application using vb.net on the 1.1 framework. > > We have in the application, some strongly typed collections that have been > written as classes that do not inherit from collection base, but use an > internal collection, to hold the objects and then implement IEnumerator, > see example below, > > > Public Class AttributeCollection > > Implements IEnumerable > > Protected intCollection As New Collection > > Public Overridable Sub Add(ByVal Attr As Attribute) > intCollection.Add(Attr, Attr.Name) > End Sub > > Public Sub Remove(ByVal Attr As Attribute) > intCollection.Remove(Attr.Name) > End Sub > > Public Sub Remove(ByVal AttrName As String) > intCollection.Remove(AttrName) > End Sub > > Public Function Count() As Integer > Return intCollection.Count > End Function > > Default ReadOnly Property Item(ByVal AttrName As String) As Attribute > Get > Return CType(intCollection.Item(AttrName), Attribute) > End Get > End Property > Default ReadOnly Property Item(ByVal index As Integer) As Attribute > Get > Return CType(intCollection.Item(index), Attribute) > End Get > End Property > > Public Function GetEnumerator() As System.Collections.IEnumerator > Implements System.Collections.IEnumerable.GetEnumerator > Return intCollection.GetEnumerator > End Function > > > End Class > > These collection allow us to do a for each loop down the collection, > > For each attr as Attribute in someAttrCollection > ... code > Next > > However, we are having problems with this type of collection so are moving > to inheriting our strongly typed collections from collectionbase. However > collectionbase does not use Key Value pairs. We have tried inheriting from > DictionaryBase, but that then stops all the for next loops from working as > the items it returns are dictionary entries, not the internal objects we > wish to get. > > I know if we inherit from DictionaryBase we can change to a > For each attr as Attribute in someAttrCollection.Values > > but there are 10's of thousands of lines of code, and we would prefer not > to have to change our for next loops if possible. > > So the question, how do we create a strongly typed key value pair > collection that allows a for next down the created collection returning > the objects contained in the value part? > > How the question is understood. > > Thanks in advance for any help or advice. > Regards, > Simon. > Hi Jim,
Thanks for taking the time to reply, What you describe is not the problem, we can easily change the collections to inherit from collectionbase, but that takes away the key value pairing, which we require. If we inherit from any of the key value type collection bases then the For Next construct down the collection no longer works, and we have to change all our for next loops to go down the values property within the collection which we do not want to do. So we are looking for a key Value type collection base, where the For Next works on the collection itself, and for nexts down the values stored, not the key value pairs. Regards, Simon. Show quoteHide quote "Jim Wooley" <jwool***@bellsouth.net> wrote in message news:eH9tz0NLGHA.2912@tk2msftngp13.phx.gbl... > The guidance (for 1.1) is to inherit from CollectionBase. To do what you > need, you may just need to modify the Item property as follows: > > Default ReadOnly Property Item(ByVal AttrName As String) As Attribute > Get > for each child as Attribute in List > if Child.ID=AttrName then > return Child > end if > Next > 'Nothing found, NOTHING will be returned > End Get > End Property > > Jim Wooley > > > "Simon" <s@v.c> wrote in message > news:43e9c74c$0$6955$ed2619ec@ptn-nntp-reader02.plus.net... >> Hi all, >> >> I am writing a windows application using vb.net on the 1.1 framework. >> >> We have in the application, some strongly typed collections that have >> been written as classes that do not inherit from collection base, but use >> an internal collection, to hold the objects and then implement >> IEnumerator, see example below, >> >> >> Public Class AttributeCollection >> >> Implements IEnumerable >> >> Protected intCollection As New Collection >> >> Public Overridable Sub Add(ByVal Attr As Attribute) >> intCollection.Add(Attr, Attr.Name) >> End Sub >> >> Public Sub Remove(ByVal Attr As Attribute) >> intCollection.Remove(Attr.Name) >> End Sub >> >> Public Sub Remove(ByVal AttrName As String) >> intCollection.Remove(AttrName) >> End Sub >> >> Public Function Count() As Integer >> Return intCollection.Count >> End Function >> >> Default ReadOnly Property Item(ByVal AttrName As String) As Attribute >> Get >> Return CType(intCollection.Item(AttrName), Attribute) >> End Get >> End Property >> Default ReadOnly Property Item(ByVal index As Integer) As Attribute >> Get >> Return CType(intCollection.Item(index), Attribute) >> End Get >> End Property >> >> Public Function GetEnumerator() As System.Collections.IEnumerator >> Implements System.Collections.IEnumerable.GetEnumerator >> Return intCollection.GetEnumerator >> End Function >> >> >> End Class >> >> These collection allow us to do a for each loop down the collection, >> >> For each attr as Attribute in someAttrCollection >> ... code >> Next >> >> However, we are having problems with this type of collection so are >> moving to inheriting our strongly typed collections from collectionbase. >> However collectionbase does not use Key Value pairs. We have tried >> inheriting from DictionaryBase, but that then stops all the for next >> loops from working as the items it returns are dictionary entries, not >> the internal objects we wish to get. >> >> I know if we inherit from DictionaryBase we can change to a >> For each attr as Attribute in someAttrCollection.Values >> >> but there are 10's of thousands of lines of code, and we would prefer not >> to have to change our for next loops if possible. >> >> So the question, how do we create a strongly typed key value pair >> collection that allows a for next down the created collection returning >> the objects contained in the value part? >> >> How the question is understood. >> >> Thanks in advance for any help or advice. >> Regards, >> Simon. >> > > 
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