Class Property Access - Setup MyClass To Work Both Ways?
May 7, 2010
I can't seem to find the correct words to search for an answer. I'm using VS 2010 so I have auto-implemented properties.I have a class and I want to access the properties by a string.
Public Class MyClass
Property Prop1 As String
Property Prop2 As String[code].....
But, I also want to be able to access the variables something like this way....
Dim MyVar = New MyClass
MyVar.Items("Prop1") = "Prop1 Value"
MyVar.Items("Prop2") = "Prop2 Vaule"
I'm using VS 2010 so I have auto-implemented properties.I have a class and I want to access the properties by a string.[code]But, I also want to be able to access the variables something like this way.[code]How can I setup MyClass to work both ways?
I have a list of properties and values that i'd like to use to dynamically build an Expression(Of Func(Of MyClass,MyClass))
I can run through the list and create each Expression by itself, but the only way I know how to combine them would be to use Expression.And or Expression.AndAlso, but that returns a BinaryExpression rather than my original Expression(Of Func(Of MyClass,MyClass)).
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
I am experimenting with a transition from my application built in VB6 to vb.net. I know, about time. At the same time, i am making changes and improving upon the original. One area that I am working on is within my employee class. very standard class, nothing fancy. One change I want to make though is allow for an employee to be assigned more than one work location. Employee has (is assigned) Stores. In reading about collections, it appears they are different in .net (as they should be), but I don't know what the sytax changes will be to implement my changes.
I've been going through a VB book I had while in College, and was trying to figure out different ways of making programs work.One assignment was to create a multi-dimensional array to figure out wind chill factors. The only part I really can't get to work right is using 2 numericUpDown controls. Using 2 dropdown menus was obviously easy because the items are indexed, but as far as I know, numericUpDown controls are not indexed.
Instead I used 2 selectCase statements to determine the index in each updown control, then passed the indexes to a function to determine the answer.The numericUpDown controls both increment by 5, (wind from 5 to 30) (temp from -20 to 15)Just looking to see if someone has any ideas of a better way of doing this.
I have a function that updates a Client in the database. A client object is passed in, along with a string array of fields/properties that should be updated. I need a way of accessing each property in the client object, based on what is in the array. Basically, I am looking for the VB .NET equivalent to this javascript:
var fields = ["Firstname","Lastname","DOB"]; for(field in fields) {
I have a class that exposes an auto implemented property Enabled
[Code]...
But If I had not use an auto implemented property and declared my own backing-field as follows this is accessible from the subclass: Private _Enabled as Boolean ---- EDIT ---- The abve line is incorrect - this is not possible, it was in fact Protected in the original code which allowed access from the sub class See @JonSkeet answer ---- EDIT Of course I can just access Enabled from the sub class to work around this but can someone explain why this is the behaviour?
In C# .NET 3.5, is there a way to instantiate an object given its string name? For example, suppose I have a DLL (e.g., MyClass.DLL) which contains type MyClass. Is possible to write something like... Object myClass = SomeMethodToInstantiate("MyClass"); // ? Is it possible to do this in VB .NET 3.5?
I have application developed in vb.net 2005 with sql server database and also used crystal report in it. I have make the setup files using deployment wizard. Now the problem is that when I install the setup files, it work on some pcs while didnt run on some others.ramework 2.0 is in its prerequisites which I install before running setup. When I try to see error message, it gives server time out
I have application developed in vb.net 2005 with sql server database and also used crystal report in it. I have make the setup files using deployment wizard. Now the problem is that when I install the setup files, it work on some pcs while didnt run on some others. Framework 2.0 is in its prerequisites which I install before running setup. When I try to see error message, it gives server time out.
I have a very simple class that holds a few public properties - ID, Text, Colour, etc. and a Boolean called 'SelectedItem'. Just like the Checked property on RadioButtons, only one item can have its SelectedItem property set to True within a particular group. Note: there will be several separate groups (lists), each allowed to have only one item with SelectedItem = True.
My first thought was that I would probably just have to handle everything outside of the class, setting SelectedItem to False for every other item in a particular list when another item was selected. But that seems rather inelegant to me. So I've been trying to think of how this might be done within the class. For example: could I perhaps have a private string property called say "GroupName" - set in the New sub when adding a new instance of the class - and then use a private shared method to set every item's SelectedItem property to False, provided the item has the same GroupName as the newly selected item? I would have a go at doing this but I have no idea how to enumerate every instance of a class from within that class, or whether that's even possible. Is it? Or is there another (better) way to achieve my goal? Here is a cut-down version of what I've got so far:
Public Class ResourceItem Public ID As Integer Public Text As String[code]....
As can be seen: instead of instantiating a new ResourceItem and passing that as an argument to the manager's Add procedure, I'm simply passing the details of the new item and the procedure is creating the item from those. I don't know whether this is a good or bad idea - please advise - but I've done it because I couldn't figure out how to make the SelectedItem property only writeable by the manager, so I wanted to avoid having directly accessible objects that could have their SelectedItem property set to True without it deselecting all the other items in the same group. Of course that still leaves the possibility of setting a variable to one of the manager's list items and setting it from there, so I would still like to know how I could prevent that, if possible.
UPDATE: I didn't use the code above in the end, deciding instead to go with Cyborgx37's solution - which seems to work perfectly well for me despite the warnings about best practice. I also realised I would need to use the same class in another scenario where multiple items could be selected, so it was easy to add a Boolean property to the manager to enable that.
Public Class MyColorsClass 'Constructors Public Sub New() 'Empty Constructor
[code]....
However, if the empty constructor was called to instatiate this class then the colortype is not yet set. Therefore, if one accesses the 'IsColorCool' property it will always return 'False'. Now for the sake of this example, I must keep the empty constructor as part of the class.Now I could add some code in the 'IsPropertyCool' to check and see if a ColorType has been defined, and throw an exception if it has not been set, but I don't really want to do that.I also could always move the logic OUT of the property and into a method on the class called 'DefineIfColorIsCool' or something, and make the owness on the caller to make sure the method was called if they want to use the property 'IsColorCool'?
Public Class airplane Private var_num_seats As Integer Private var_num_engines As Integer
[code]....
Obviously, I don't wish that the class Glider has the method "start_engines" neither the property "num_engines". Otherwise, other child classes may have. How can I supress these property and method in child class, not just ignoring (if I can)?
I have procedure (Import) that calls a for a new instance of frmImportData. I also have a class name clsBatch that has a data table property called prpParametersTable.For some reason, I get an error (indicated below with ERROR>>>) when trying to assign prpParameterTable to cv_dtImport2. The error states "Object reference not set to an instance of an object.". Why does this error not happen when I assign dtBP to cv_dtImport1? Both cv_dtImport1 and cv_dtImport2 are equal to Nothing and in my Import procedure dtBP = prpParametersTable.
Public Sub Import(ByVal clsB As clsBatch) Try Me.cv_clsB = clsB
I have three class files, accounts.vb and transactions.vb in addition to my form.vb. I am unable to retrieve a member variable from on class from inside the other. When the combobox index changes, the program loads the correct account (checking or saving) from two different sequential files. I don't think I have the calcBalance procedure in the correct class file. And that is what I am having trouble with. Accessing it to display it. [Code]
The default installation of my setup project is as follows:
[ProgramFilesFolder][Manufacturer][ProductName]
The problem is PC in Europe don't have a "Program Files" folder, it's in a different language.When I remove [ProgramFilesFolder] from the setup program, the installation doesn't work. I would like to install the application in C:AppFolder,
start with I was given a program by a friend that was created in Excel 2003 with the help of Visual Basic Editor. He said he used Visual Basic 2003, which he is not 100% sure about. Anyways he used CurLine in the program and when I try to open it in Excel 2007 and then open the Visual Basic Editor and run the program I get the following error:Run-time error '-2147418113 (8000ffff)':Could not get the CurLine property. Unexpected call to method or property access.
I'm looking for a tutorial on how to Adding a list(of Class) or Collection as another Class's Property.What I am after is something like the Columns Collection for the DatagridView control.I would like to add Items in the graphics screen. Where the item list is displayed in the left panel and the selected Item properties are displayed in the right panel.
This code snippet was converted from the c# snippet on this link A ChildWindow management service for MVVM applications There are two classes in this snippet first is my confirmessage class
[Code]...
Now this works fine in C# , however in vb,net the line where I add the event handler generates the following error on the message.callback property : Property access must assign to the property or use its value I am tearing out my hair on this I have never used the Action of T delegate before so could i be missing something simeple ? I can provide the c# code as well.
got an ErrorProperty access must assign to the property or use its value.Here i attach the code which have an error.In this program i tried to add data into form . I also create button , textbox. i am using visual studio 2005 and sql 2005. i also have attach the imagece
Private Sub btnregister_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnregister.Click admin1.LoginDataSet.staff(Me.NAMETextBox.Text, Me.TELEPHONEMaskedTextBox.Text,
I have a class that has the following property that is generated by the methods in the constructor.
Public Class clsLoadTables Private _ds As New DataSet Public Property ds() As DataSet Get
[CODE]........................
My problem is that I do not want to inherit this class, but I have other classes that need to access the ds DataSet property. If at all possible I would like to not use inheritance and not load my datatable more than once in the program.
Here is my failed attempt to access the property inside another class that is not inheriting clsLoadTables:
[CODE].........................
How I can access this dataset that I want to load only once in the program from many classes without using class inheritance or a global module?
I know that an interface can contain another interface within it.But;can a class contain another class within it?Can an interface contain another interface within it?
I have a Class that will automate processes based on a set of variables. I have a finite number of boolean variables. If True, the process will run, if False, it won't.If a variable is True, I'll add it's corresponding process to a Queue of processes.What I'd like to know, is how should I setup the processes? Should it be in the new class or form class? Should it be at class level or not?
I was thinking I could just setup each process at Class level:
VB.NET Private p1 As New ProcessPrivate p2 As New ProcessPrivate p3 As New Process
Then, before the process is added to the Queue, I'll assign the appropriate properties.
Is there a better way? Or will this work just fine?
