VS 2010 Polymorphism Gone Awry?
May 20, 2011
I have a class that has two methods called "Add." One method excepts a FileInfoA object and the other excepts a DirectoryInfoA objectSo in my code, I'm adding FIAs and DIAs to property lists. But, it throws an exception because it's trying to process a FIA as a DIA, which means that the FIA is being added to the group of DIAs.I commented out the adding of DIAs to see if it would work and it did. When the DIA is commented out, the FIAs are filtered properly and the code executes properly.This is how my methods are declared:
VB.NET
''' <summary> ''' Adds a DirectoryInfoA class and adds it to one of the appropriate list. ''' </summary> ''' <param name="di">DirectoryInfo</param> '''
[code]....
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Jan 6, 2012
I have a function called Modify. It is delcared like so:Public Function Modify(Of SIMType As {New, DAOBase})(ByVal obj As DAOBase) As Boolean
You can see that this function is generic. It takes as a paramer a object that is a DAOBase or subclasses of DAOBase.Inside the modify function there is a call like so:
DAOToGP(obj)This is where the polymorphism comes into play. There are four or so subclasses I have created of DAOBase. I have written a DAOToGP() for each of these types. So in the Modify() function, when it calls the DAOToGP(obj), polymorphism should kick in and it should call the correct implementation of DAOToGP() depending on the type that I pass into Modify().
However, I get the following error:Error 20 Overload resolution failed because no accessible 'DAOToGP' can be called without a narrowing conversion:'Public Shared Function DAOToGP(distributor As Distributors) As Microsoft.Dynamics.GP.Vendor': Argument matching parameter 'distributor' narrows from 'SierraLib.DAOBase' to 'IMS.Distributors'.'Public Shared Function DAOToGP(product As Products) As Microsoft.Dynamics.GP.SalesItem': Argument matching parameter 'product' narrows from 'SierraLib.DAOBase' to 'IMS.Products'. C:Usersdvargo.SIERRAWOWIRESDocumentsVisual Studio 2010ProjectsSIMDev_2SIMIMSDVSIMLibGPGPSIMRunnerRunnersRunnerBase.vb 66 39 IMS
I am kind of at a loss here. I am not sure why it cant figure out which function to call.
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May 15, 2009
Okay this is a bit of a noobish question, but I ran across this today and it somewhat puzzles me WHY it would be this way.
Consider the following structure
Public Class Employee
Implements IPerson
Private _MyManager As Manager
[Code].....
Here is my question: I am wanting to have every person implement the IPerson interface, whether they are an employee, boss, or manager. However, they each have an attribute that refers to their leader (employees have a manager, managers have a boss, etc). Each implementation of their leader could be potentially differnt other than they fact that they implement the IAuthorityFigure interface. I am wanting to have the IPerson interface have a property for the IAuthorityFigure, but it throws a compiler error for me when I implement this b/c the IAuthorityFigure is not the same type as Boss or Manager (even though they implement the interface).
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Oct 29, 2011
i have assignment which using polymorphism to get answer. Below here is answer from the question.anyone give me a code using polymorphism to get this answer
i= 100, j= 200, k= 300
value for i =100
value for(i+j)/2= 150
value for(i+j+k)/3 =200
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Jan 31, 2012
I wasn't quite sure how to label this but that should cover it all. I am using Linq to Sql classes to query a SQL Server table. That part is working fine. I'd like to add the records to a listbox and not just text. I can do this and it works. To get it to display something meaningful in the listbox, I have to override the ToString() function.
So, I've taken the base class tblVendor and created a new sub class tblVendorListObject that inherits tblVendor and overrides ToString to return Me.vendorName. I then use a foreach loop to iterate through the records returned by the query. Next, I create a new instance of tblVendorListObject and attempt to assign the current item in the foreach loop to it.
[Code]...
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Nov 17, 2009
I have a couple of small classes to represent parts in a search filter. If the searched value equals NonValue the filter is supposed to do nothing. This is defined in a Base Class:
Private Class BaseFilter
Protected NonValue As Object
Protected sQueryStringBase As String = "AND {0} {1} {2} "[code]......
When I then create a StringFilter and check for allowed value:
Dim stf As New StringFilter()
stf.CheckNonValue(MyString)
I get a NullReferenceException (NonValue = Nothing) , when I expected the NonValue object to be String.Empty. Is this a bug in my code, or am I trying to achieve polymorphism in a wrong way?
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Mar 24, 2011
Suppose I have an interface IFoo with implementation classes VideoFoo, AudioFoo, and TextFoo. Suppose further that I cannot modify any of that code. Suppose that I would then like to write a function that acts differently based on the runtime type of IFoo, such as
[Code]...
Then I have to do my "If TypeOf ... Is" again. How can I refactor this to take advantage of the polymorphism of the implementations of IFoo without manually checking the types? (in VB.NET, though my question applies to C# too)
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Sep 16, 2011
In VB.NET, say I have a function Public Function Foo(ByVal currentShape as Shape) Instead up passing in a Shape object, I pass in a subclass of Shape called Square like such: Dim square As Square = new Square() Foo(square). Do I need to convert my Square object to a Shape object before passing it in? If so, how do I do this?
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Mar 8, 2010
Can you define this :
Class
Object
Inheritance
Polymorphism
Abstraction
And could you make it easy to understand I'm having a hard time to understand those terms.
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Jan 29, 2010
In a program I am writing (in VB.NET, 2008), I have 2 classes, "Receipt" and "Group", each with similar properties, both implementing a custom interface entitled "IIDUser". In my program, I have a number of lists of "Receipt" and "Group", declared like:Friend receipts as List(Of Receipt)
I have written a few functions that apply equally to managing both lists of receipts and groups, declared like this one:Friend Function getNextAvailableUserLabel(ByRef theList As IList(Of IIDUser), ByVal startLabel As Short) As Short
Then called like this:getNextAvailableUserLabel(receipts, s)
I did all this in an attempt for interface-based polymorphism, as I thought writing 2 identical functions (except for that one would be for lists of receipts while the other for lists of groups) would be bad practice (and waste time). However, I get an "InvalidCastException" during runtime. It is explained, "Unable to cast object of type 'System.Collections.Generic.List`1[Receipt_Sorter_v2.Receipt]' to
[Code]...
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Feb 16, 2012
I'm trying to create a class for storing data on People with another class to store their Bank Transactions.Ideally, this all be hidden away and leave only simple statments, declarations and functions available to the programmer.[code]I know this is possible as these exist in the Listbox Class though can't figure out how it's done.
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Oct 2, 2010
When trying to import CrystalDecisions.CrystalReports.Engine, and CrystalDecisions.Shared. I'm getting a green line. What might be the problem?
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Jan 8, 2012
I'm new to visual basic, used it for a few months. My friend is addicted to using a program called Wpe Pro [URL].. and he wanted me to make it more advanced and able to do more stuff.if you no anything about this program please message me
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Aug 4, 2011
VB.Net 2010 program .exe on PC with Excel 2007 gives error when cannot find Excel version 14, which is Excel 2010 I have developed a program in VB.Net 2010 which reads from an Excel spreadsheet. It works fine in the IDE on my computer. I built an .msi and executed it on my computer. I get "Error: 53 - Could not load file or assembly 'Microsoft.Office.Interop.Excel, Version=14.0.0.0, Culture=neutral,PublicKeyToken=71e9bce111e9429c' or one of its dependencies. The system cannot find the file specified."
The only version of Excel on my computer is 2007, which is version 12.0.6557.5000. The version the error says it needs, version 14, is actually the version of Excel 2010.I have put in MsgBox statements to find where the error occurs.
[Code]...
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Jan 5, 2011
At present I have wrote an application (in-house CRM, vb .net 2010) which allows me to send emails under the selected customer & I categorised these emails.As these are categorised I can return data to display email history in my program by using search criteria:
Dim oMail As Outlook.MAPIFolder = oNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderSentMail)
Dim sSearch As String
sSearch = "[Categories] = '" + "[" + tAccount.Text.Trim + "]" + "(" + tShipTo.Text.Trim + ")'"
Dim oItems As Outlook.Items = oMail.Items.Restrict(sSearch)
However the limitation to the above is it only looks at sent items & no other folder.My ideal solution would be to display all email correspondence for a certain contact.
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Jun 6, 2012
The situation: when i build my project (or publish) Visual Basic 2010 makes and exe and a couple ddl files. when i run the project with the .exe and the other files the program works perfectly.
My problem: I want to share it with friends and it is just a verry little program ( a n internet radio) so i want it to be 1 .exe with out any other instalation needed so i can easly share it to anyone who wants it. when i make an even smaller program and Debud->build it, it is only 1 exe and no instalation needed. so is there a way to make my program to 1 exe only?
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May 26, 2010
Basics Details:
VS 2010
Making an Addin for Excel 2010
Win 7
Problem:I am not getting the cursor (4 arrowheads) for moving the form.I am using the Panel1_MouseHover to display the cursor. Right now if I choose any other cursor then it is working but the same cursor also displays when I hover the mouse over any other control. I want the cursor to show only in the areas of the Panel where there are no controls.How do I show Tooltips for the images? The play,stop,next, previous,playlist,Hideme(with the smiley),volume are all images and not buttons?
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Jun 21, 2010
Well I used the Visual Studio 2010 installer to install my application and I want it to be able to change the version displayed in the in the Add/ Remove Programs (in the Control Panel). How can I do this without going through the install wizard again?
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Aug 19, 2011
If I create a DLL using VB 2010 express can it be used by previous versions of of .Net (3.5, 2.0)? Will the DLL use .Net 4.0 components, which is what I want. I don't see a way to force that to be the case.
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Mar 26, 2012
this is my very first posting and I must say I am desperate. I have a VB assignment due in 2 days and I am so lost. I have written a code to draw some graphic, just a basic house, tree, sun etc. I have also written a code to magnify said graphics which were all the specifications of my Assignment 1 part A. Now for Part B I am being asked to extend my program so that: A - My graphic can be drawn using different colour schemes designed by me but chosen by the user B - My graphic or an appropriate part of it can be animated around the picture box if the user chooses to do so. C - Error checking is included.
[Code]....
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Jul 16, 2011
it's just for a program registration. i would store all of the registration codes in the access database, then export it to XML, then upload it to my web host. I would then somehow connect it to my Visual Basics login form (Which I have already made). If this can't be done, having them register through the form and having all the allowed codes on the internet (So i can easily edit them)!
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Mar 7, 2012
Is it ok to install my VS 2010 Ultimate even if I already have VB 2010 Express Edition? or should I uninstall the express edition first?
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Aug 11, 2011
well until a few day ago. I don't know what I have introduced to cause the problem but now, whenever I load the project, VS 2010 (SP1) crahes. If I delete the project's suo file, the project loads (really quickly) and all is well until I exitVS 2010. When I re-run it and try to load the project, it crashes again unless I delete the suo file.The program can be built for x64 and x86. Now, when I reload the project (after deleting the suo file), it comes up in Debug - Any CPU mode. I can change from Debug to Release and from Any CPU to x86 but if I try and change from x86 to x64, VS 2010 crashes.This is not always the case though. If I build the x86 version and then switch to x64, all is well and I can build the x64 version. Obviously, there's something wonky going on.
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Feb 14, 2011
I need to write from VS 2010 vb.net dataset into a newly created xlsx file.
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Nov 3, 2011
Here are my questions concerning VB 2010 Express:
1. I've registered my VB 2010 Express, will it still expire?
2. Will the applications I made using VB 2010 Express expire after some time?
3. Is it OK to write my code in the designer.vb file? I don't know why, but when I started writing my application it took me to the designer.vb instead of form1.vb code.
4. I've been working on an application for a week now, but suddenly I can no longer access my Design View(Shift-F7). All my codes are written on the [form name].Designer.vb. I can still view my codes but I cant access my form layout. On the solution explorer, my forms no longer have the 'form icon'. When i press Shift-F7 nothing happens. Right-clicking the form on the solution explorer doesn't show 'View Designer' option. How can I fix this?
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May 16, 2012
I have a datagridview populated from a CSV file in vb.net. I have 2 datepickers, 1 button. see the attached images. Image1->before filtering
[Code]...
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Nov 6, 2011
Dont be afraid to spam the thread with things you can create.The more the better!
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Mar 18, 2012
I'm having a little trouble trying to read a word document in vb. how to get the text out of the word document would be great.
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Apr 1, 2012
Syntax error (missing operator) in query expression '''system time'''.this is the error that appears
this is my code:
Dim sqlCmd As String
Dim x As Date
x = Format(Now(), "General Date")
[code].....
the fields in the tables are all text fields.is there any way to fix this error? perhaps it is in my query but i really cant find a solution.is there an alternative to get what i want my program to do?it is basically entering an ID number and finding the record with the same idnumber and putting the system time on the timein field for that record.
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Apr 20, 2010
I have the following extension method. However, when I type "File." this method doesn't pop-up. What did I wrong?
[Code]...
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