Call A Member Through Its Parent's Type That Shadowed A Parent Class Implementation?
Aug 3, 2011
This is a challenging one that got me stumped while I was coding today. Suppose I am running the Sub Test1() and Test2() and would like to print out the value of the Shadows method of the instance of the object I am passing in to TestCall() (see below - it is clearer) using the following restrictions:
Can't change the contents of Class A, B, and C
Can't change Sub Test1() and Sub Test2()
TestCall() can't have an if, select case etc. statement that tries to figure out the type
[code].....
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Feb 27, 2012
VB Reference parent member of a class through a child when using List Of(T)?
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Jun 24, 2009
I have a main form, and some sub forms, and each sub form can have some sub forms. When I have multiple sub forms open, and I try to get data from the parent form, it returns the data from the wrong parent form.For example I have two instances of Mainform.subform running. If I do something like this in a child form of one instance of the subform. It returns data from the other subform.
dim l = Mainform.subform.listofdata
Edit:I am using visual Studio 2008. Winforms, form designed using designer. In my mainform I am doing this
Protected Friend frmMain as Mainform
frmmain = new mainform
In frmMain I am doing this
Protected Friend frmsub as new Subform'
frmsub = new subform
[code]....
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Feb 16, 2010
I will try to explain what I need.Let's say that I have a class like this:
Public Class Example1 Public Sub ToBeCalled()
[Code]...
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Apr 10, 2010
I would like to know if there is some simple code to release a child control from it's parent control, without having to name the parent control. In pseudocode, I'm looking for something like this:
[Code]...
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Sep 25, 2011
I have a class inhert ToolStripButton. it builds a new toolstrip button. the button will be added to the toolstrip which is on main form.
I will need call function in the main form. what's the right way to do this?
now, I pass the main form when create the class. but I guess the right way is to raise the event in main form.
but, how about the properties in main form?
if I raise the event, will it run the event first, then go to the next line of the class? or, just raise event, then go to the next line in the class immediately?
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Feb 8, 2012
I am trying to create a project in VB 2010 like I have in VB6. In VB6 I have a parent form which opens a child form. The child form displays calls (customers) on a spread sheet control that are on hold. The user selects the call in the child form, it calls a sub in the parent form passing a record number to identify the customer. The parent form then "pulls" up the call and and connects the user to the caller with all of the customers information.So, I haven't done this in VB NET and I have searched to see if this would be done the same way in .NET as it was in VB6, but I haven't found much decisive information. Is a parent/child form the way to do this?
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Jan 12, 2011
I have a bunch of VB.NET programs that have a general purpose logging function to log events, errors, exceptions, etc. It looks like this:
Sub LogMe(Msg as string)
LstLog.items.add(now.tostring & " " & Msg)
End Sub
I wrote a few VB.NET DLLs that contain classes used my my VB.NET programs. In thoses DLL classes, I would like to also trap some events, errors, exceptions, etc. But I want them to be logged using my main LogMe function. Here is some pseudo-code of what I was looking for:
' Main program code
imports MyLib
' Initialize program
[Code]...
I assume I will need to define Delegates to save my LogMe fonction pointer
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Feb 8, 2009
main Form1 has button1. What code do I need in button_click event to call and run Form2(or dialog1) which has been added to the project.
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Feb 21, 2011
main Form1 has button1. What code do I need in button_click event to call and run Form2(or dialog1) which has been added to the project.
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Jun 7, 2012
I want to created a nested class that can only be visible to and instantiated from the parent class.But I also want to be able to use an instance of the nested class through a public variable of the parent class.I tried making the nested class private, or making the nested class' constructor private, but it won't compile.Is it possible to do this in .NET?
[Code]...
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Feb 5, 2011
E.g. I have a class:
Namespace Common
Public Class AClass
Public Class BClass
[code]....
How can I use BClass without saying AClass.BClass, I've see some existing code using this format, but I can't find the setting.
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Nov 17, 2009
I'm trying to make an MDI parent form to call other forms. I have put this code which I found in a post here into the main form which I added to my project as an MDI parent form:
[Code]...
I get an error message which say FrmEmbed is not defined. How can I correct this?
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Jan 1, 2012
I have Class1 and class2 which is inside class1, VB.NET code:
Public Class class1
Public varisbleX As Integer = 1
Public Class class2
[code]....
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Apr 11, 2009
I have a 'property management class' that contains several functions and properties. I have several other classes that use the 'management class' as a property to derive the value of several of its other properties.Is there a way for me to reference the outer class from the 'management class' functions without having to pass it as a parameter? I ask because several different classes can have this 'management class' as a property and am having a hard time typing the parameter.
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Mar 30, 2010
This is a bit of a continuation from a previous post for which AtmaWeapon was very informative.
Problem:
A parent class has a sub class with various properties. A property of the parent class is a List(of T) with T = the sub class The issue is how to store data in the sub class of the instantiated parent
Some example code (hopefully formatted correctly):
Code:
'=========== Class Definitions =============
Public Class courseClass
Public Class timeTableClass
[Code].....
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Jan 2, 2010
I have a Parent Class Called Fuselage that containsfour child classes called Forebody, CenterBody, AftBody, and CrossSection. CrossSection classcontains objects common to Forebody, CenterBody, and Aftbody (example: width). How do I access thewidth property in CrossSection from within the classForebody?
Public Class Fuselage
Dim Forebody As ClsSection
Dim Centerbody As ClsSection
[code].....
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Dec 16, 2009
If Class X is within the scope of Class Y, is X a subclass of Y?If Class A is a sub Class of B, then is Class B considered a super class of A?if Class C inherits Class D is Class D a superclass or parent of Class C?if Class E extends Class F then we can consider Class E a child of F?if Class G inherits Class H and is within the scope of Class I then who is the parent of Class G? Classes that inherits Class J and classes that are within Class J are all sub classes of Class J?
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Feb 3, 2009
I could put a Textbox in a Panel then that panel is placed in a TabPage, how do I go out going through the hierarchy of the Textbox parent until reaching the TabPage? My purpose for this is if I want to focus on a Textbox then of course I would have to also select the TabPage where it is located, is there an easier way than what I am planning to do?
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Mar 31, 2012
I have a problem that is frustrating me to no end, I have a overrideable function in a parent class, and the override function in the child class, like below:
[Code]...
When i debug, the value is produced, but it doesn't carry over to the parent class of ski.RetailPrice()what seems to be the problem here?
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Feb 28, 2011
I am creating an xlsx reader / writer for my application (based on OpenXML SDK 2.0). I want to read xlsx files and store the data contained in each row in a DTO/PONO. Further I want to read the xlsx file and then modify it and save it.Now my problem is not with the OpenXML SDK, I can do what I need to do.My problem is on how to structure my components. Specifically I have problems with the polymorphism at the lowest level of a Spreadsheet, the cell.A cell in Excel/OpenXML can have different types of data associated with it. Like a Time, Date, Number, Text or Formula. These different type need to be handled differently when read/written from/to a spreadsheet.I decided to have a common interface for all subtypes like TextCell, NumberCell, DateCell etc.Now when I read the cell from the spreadsheet the Method/Factory can decide which type of cell to create.
Now because the cell is an abstract from the real implementation it does not know / does not need to know of what type it is. For writing / modifying the cell I solve this problem by calling .write(ICellWriter) on the cell I want to persist. As the cell itself knows what type of data it contains, it knows which method of ICellWriter it needs to call (static polymorpism).Writing to the xlsx file is no problem. My problem is, how do I get the data out of my cell into my DTO/PONO without resorting to type checking -> If TypeOf variable is ClassX then doesomething End If. As Methods / Properties have to have different Signatures and differentiating by only using a different return type is not allowed.The holder (collection, in this case a row of a table/spreadsheet) of the objects (refering to the cells) does not know the concrete implementations. So for writing a cell I pass it a Cellwriter. This Cellwriter has overloaded methods like Write(num as Integer), Write(text as String), Write(datum as Date). The cell object that gets this passed to it then calls the Write() method with the data type it holds. This works, as no return value is passed back.After some thinking about the problem I came to realize that it's not possible without reflection or knowledge of what type of cell I am expecting. Basically I was trying to recreate a spreadsheet or something with similar functionality and way too abstract/configurable for my needs.
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Nov 18, 2009
Implement singleton in a parent class.Infact what I want is that All the childs etc. should use same instance of the parent.
I have implemented singleton, Changed the scope of parent class's constructor to "Protected". But in the application when ever the new child's constructor is called i.e. "Dim abc as New Ch1()" the constructor of Parent is called (as it is Proctected and can be access from child).
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Nov 18, 2009
implement singleton in a parent class. Infact what I want is that All the childs etc. should use same instance of the parent.
I have implemented singleton, Changed the scope of parent class's constructor to "Protected". But in the application when ever the new child's constructor is called i.e. "Dim abc as New Ch1()" the constructor of Parent is called (as it is Proctected and can be access from child). Which is undesired behaviour.
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Oct 12, 2011
I have a listview "CategoriesList" and i have a repeater "NewsRepeater" inside the listview "CategoriesList"
<asp:ListView ID="CategoriesList" runat="server" DataKeyNames="CatID" DataSourceID="CategoriesListODS"
EnableModelValidation="True">
[Code]....
how to pass the catID from the listview and make it as SelectParameters in ObjectDataSource "NewsRepeaterODS"?
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May 14, 2009
I would like to have a form class that is called from a button on a parent form and would like a button on the child form to set a property on the parent form. Can anyone explain the best way to go about this or direct me to a good article?
[Code]...
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Jun 24, 2009
In general, according to the OOP paradigm, my understanding of encapsulation basically says:
-If a member is private, it can only be accessed by the class.
-If a member is protected, it can only be accessed by the base class and any derived classes.
-If a member is public, it can be accessed by anyone.
If I have a nested class, can I declare a property to be accessible only to that class and the parent class it's nested within? For example:[code]In the example, I cannot directly access myNestedObject.myInt or myNestedObject.myDbl from an instance of ContainerClass if those members are Private or Protected. But suppose I don't want to make them Public,because then they are TOO exposed: they can be altered from anywhere, not just within a Container Class object. Declaring them Friend would still be too weak as that would allow them to be altered from anywhere within the application.
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May 6, 2010
I have a collection class, say ITEMS, that inherits a Dictionary (of String, SINGLEITEM). From the SINGLEITEM class, I would like to reference a property in the parent ITEMS class, what is the best way to do this? For example, say the ITEMS class has an IsDirty property and I would like to set that if ANY of the contained SINGLEITEM objects is modified, what's the best way to go about doing this?
I know I could add a reference to the collection class in each SINGLEITEM class (since I override the ADD method, I could make this assignment), but this seems like overkill.
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Nov 2, 2009
I've created a class that inherits from Dictionary(Of TKey, TValue) called KeyCopyDictionary(Of TKey, TValue). I'm now trying to use a pre-existing function which returns a Dictionary(Of String, String) and assigning it to a variable of type KeyCopyDictionary(Of String, String). I'm getting an invalid cast exception. Is it not possible to assign a variable of a parent type to a variable of its child type? I've tried DirectCast and CType to no avail on this...
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Jun 27, 2012
I have 2 pages. parent.aspx and child.aspx. In parent.aspx, i use colorbox and send some value for the child.aspx to popup.
[code]...
child.aspx will popup and shows ASPxGridView base on the value passing from parent.aspx. User will select the data from ASPxGridView. the selected data need to send back to the parent page. I code it in child.aspx.vb page.My problem is how can i get the value from child.aspx.vb and pass it to parent.aspx ?
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Jun 3, 2011
I have two forms. Form A and Form B. Form A has a datagrid that is populated from a SQL Database Table query. When a button is pressed Form B is launched that allows you to add a record to the database table. I need for the datagrid to be refreshed and show the newly added record when I close form B and go back to the parent.
[Code]...
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