C# - Can A Property Return A Default Value
Sep 27, 2011
Is there anyway to have a class that can return a default type without specifying the property.
If I had a class that had a few properties and one property returned a string value and others returned additional types, could I do the following?
Dim StudentGrade as new StudentGradeClass
'call and get default property
Dim CurrentGrade as string=StudentGrade
'instead of this
Dim CurrentGrade as string=StudentGrade.Current
The reason I am asking this is when I have classes that have other classes as properties and would like to just get a default return value,.
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Jan 5, 2009
I believe that the correct way to give a property a default value is to use the Default Attribute on the Property.[code]In the property window, the value that's displayed in a grid's property bag when it's newly dropped onto a form is False, not True. It does recognise that the default value should be True because it shows the value as bolded and then de-bolds it when we manualy set it to true - but it doesn't respect the default as the initial value. Is there any way of getting the property bag to respect the default value?
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Nov 1, 2009
in my following code, i get the warning doesn't return a value on all codepaths
Public Function getbacktrace(ByVal backtrace As Integer) As StackFrame
With New System.Diagnostics.StackTrace()
If .GetFrame(backtrace + 1) Is Nothing Then
exit function
[code]....
if i change exit function to return new stackframe,anyway, why doesn't Exit Function automatically returns a "dead" stackframe?
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Jan 18, 2012
Can a function return a value byref instead of the default byval? That is to say, allow me to directly edit the variable that it is retrieving instead of just giving me a copy of that variable.Right now I'm trying to write a function that will return, based on what the user has selected through a combobox, a particular setting (eg. My.Settings.somethingHere). I then want to be able to edit the setting directly through just calling the function. Is that at all possible?
[Code]...
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Dec 11, 2009
In vb.net datagridview the default Enter/Return key behavior is to move to the next row is there a quick and easy way to avoid that.
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Nov 26, 2009
So i have this code that changes the size and the font of the text but my problem is that how can i make the font and the size of the font to return back to default after it runs this code.
ListView1.Items.Add("Found Files In C: ")
My code
Dim Font As Font
Font = ListView1.Font
ListView1.Font = New Font(Font.Name, 32, FontStyle.Bold)
[Code].....
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Oct 7, 2010
For a given class, with a default property of list, you can access an instance object in the list by doing myClass.defProperty("key"). You can also achieve the same results by typing myClass.defProperty!Key.
I have been told that using the parenthesis and quotes is faster for the way the runtime accesses the Property, but I'd like to understand what is the difference and how do each work...
I understand C# has a similar behavior by replacing the parenthesis with square brackets.
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Mar 8, 2011
I'm attempting the following:Default Public Property Data(Of dataType)(ByVal key As String) As dataType
Get
Return DirectCast(values.Item(key), dataType)
End Get
Set(ByVal value As dataType)
values.Item(key) = value
End Set
End Property
[Code]...
It made more sense to make it a property, and it would be the default property of the class. The data type can not be specified on instantiation of the class, because it can contain multiple objects of different data types.
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Oct 15, 2009
I'm attempting the following:
Default Public Property Data(Of dataType)(ByVal key As String) As dataType
Get
Return DirectCast(values.Item(key), dataType)
[code].....
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Jan 5, 2012
I have a FontFamily property, but I don't know how set the default value:
Public UnitsFontFamilyProperty As DependencyProperty = DependencyProperty.Register("UnitsFontFamily", GetType(FontFamily), GetType(ValueAndUnit), New FrameworkPropertyMetadata(New
[Code]....
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Jun 13, 2011
I'm converting Visual Basic.Net code to C# in my project. But I have some doubts on how to convert Visual Basic default property to C#. The first option that comes to me are the indexers. Lets imagine the next code in Visual Basic
Public Class MyClass
Dim MyHash as Hashtable
Public sub New()
[Code]....
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Dec 22, 2011
The following XAML produces an AmbiguousMatchException. The DataContext for myText is a DataTable consisting of > 1 row which contains a DataColumn named "test":
<TextBox Name="myText" Text="{Binding Path=Rows[0].Item[test]}"/>
When I modify the binding path syntax to the below example, the binding works as expected:
<TextBox Name="myText" Text="{Binding Path=Rows[0][test]}"/>
Given that the name of the DataTable is "myData", both of the following lines of code reference the contents of the column "test" on row 0:
myData.Rows(0)("test")
myData.Rows(0).Item("test")
Why doesn't the syntax that explicitly names the Item property appear to work in a binding scenario?
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Jan 12, 2012
I am inheriting my own DataGridView (say MyDataGridView) from the standard DataGridView control. What I want is that certain properties of MyDataGridView should have a different default value than what its base have. For example, AllowUserToAddRows, AllowUserToDeleteRows, AllowUserToResizeRows properties should have the default values of False; so that when I drag MyDataGridView into a form in the IDE, the default values shown in the properties grid should be False. Later on, if I want to change them to True from the grid, they will be set accordingly.
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Apr 2, 2010
I am new to classes, and I am new to Visual Basic in general, but I am working on a multi class program. The code seems to be correct, but I am trying on instantiate a class oject with the code:
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Jul 4, 2012
I am making a new class that requires a lot of input information. Some of the properties need to be set to a default value, however I do not want to hard code them into the class.
What do you think would be the most efficient way to populate these properties?
I've been thinking of making a new class to hold all the default props and pass them as one object into the new class as a single argument but it seems kind of clunky.
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Sep 16, 2009
Given a simple class like this:
Public Class clsOB
Implements System.ComponentModel.INotifyPropertyChanged
Private _Frequency As Double
Private _Value As Double
Public Event PropertyChanged(ByVal sender As Object, ByVal e As
[Code] .....
And then I'd like to do something like this:
Dim
o As
New
clsOB(50, 30)
o = 31
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Jan 12, 2010
What is the difference between these two methods for defining property value defaults? [code] Is there a reason to use one method over the other for defining the default property values in a class?
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May 23, 2012
I have a class classed class1.vb, it has a public property named prop1 with a get and a set clause. I add one to the value passed in the set clause and in the get clause return the value variable as determined in the set clause. However, I get an error on the variable in the get clause...
Public Property prop1()
Get
Return value
[Code].....
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Oct 28, 2010
I am getting a strange error when I try to build my solution. The error occurs when I am calling the oGetHeaderValue function and passing the parameters.
Dim oGetHeaderValue As New clsGetHeaderValue
Dim returnString As String
returnString = oGetHeaderValue(strInvoiceNumber, strOrderNumber)
The error message is: Class 'clsGetHeaderValue' cannot be indexed because it has no default property.
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Nov 11, 2010
I use the following line of code within a single method to explicitly check and trust an SSL cert from the following host: MyTrustedCompany.com:
ServicePointManager.ServerCertificateValidationCallback = Function(obj As [Object], certificate As X509Certificate, chain As X509Chain, errors As SslPolicyErrors) (certificate.Subject.Contains("CN=MyTrustedCompany.com"))
No problem with the code -> works perfectly 100%.
The problem is, it is too far reaching. I thought its scope would only be within the method I decalred it, but apparently it is a Shared property on the 'ServicePointManager' object, and must then persist for the entire application, which I do not want.
The problem is later I am calling web services of mine, etc and getting the "Could not establish a trust relationship..." exception. This is because in the line of code above I check for the host name of an SSL cert specefic to that method. I quickly tested Returning 'True' from the callback so all certs would be trusted instead of checking for a specefic name (i.e. MyTrustedCompany) and subsiquent requests worked. This is how I know this callback assignment reaches father than that single method. Sure I could extend the callback to include all other certitificate names, but what I would rather do is set the 'ServerCertificateValidationCallback' back to its default behavior. Like the pseudo code below:
ServicePointManager.ServerCertificateValidationCallback = Nothing 'Default checking behavior
How do I remove the custom validation and set it back to its default behavior?
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Jan 12, 2012
I am inheriting my own datagridview (say MyDataGridView) from the standard datagridview control. What I want is that certain properties of MyDataGridView should have a different default value than what its base have. For example, AllowUserToAddRows,
[Code]...
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Mar 20, 2009
Option Strict Off
Option Explicit On
Module ModGlobal
[Code].....
End ModuleI am getting this warning s when i upgrade from VB 6 to VB.NET .,I am verz new to this Visual Basic .
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Mar 11, 2009
I need to set the default property of a dotNet Control used by an VB6 Application.
<ComClass(myControl.ClassId, myControl.InterfaceId, myControl.EventsId)> _
<DefaultProperty("NewProperty")> _
Public Class myControl
[code]....
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Apr 26, 2012
I am newer in VB NET.
VB code:
Public Class InputBox
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim a, b, S, p
a = InputBox("Enter length")
b = InputBox("Enter width")
S = a * b
p = a + a + b + b
End Sub
End Class
In InputBox lines i get this error:
Class 'LearningVB.InputBox' cannot be indexed because it has no default property.
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Jan 9, 2010
I create a class "Planet" that can be inherited. One of the purposes of inheriting is to create a template with different default property values. Eg:
Public Sub New
MyBase.New
MyBase.ForeColor = Red
[code]....
Now, to stop the defaults serializing in the InitializeComponent method, there are 2 ways:If I've implemented the properties using the 'DefaultValue' attribute, and made them overridable, the attribute can be overriden with the new value.The problem with this is, there's no way to just make just the attributes overridable, as opposed to the whole property.I could implement every property with protected Reset'PropertyName' and ShouldSerialize'PropertyName' methods. However, this is a bit of a pain in the arse.Is it, generally, an important consideration to ensure that someone who overrides your base class has the ability to change the default values of a property?
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Apr 18, 2011
The BackColor of the forms in Visual Studio are a light grey, called Control in the Properties panel. How would I set the BackColor property of a Label to this default color?
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Aug 24, 2010
I am creating a customised version of the ListView control and there are several of the properties that a ListView has that I would like to be set to a different value to the ListView default when a user goes to use my user control.
From what I've found there seems to be a number of people suggesting just set them in the constructor, but to the best of my knowledge that would just mean that the user would not be able to change the properties in the PropertyGrid in the VS IDE.I assume this is probably something extremely simple that I have overlooked.
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Nov 29, 2011
Am getting: "Structure cannot be indexed because it has no default property". What am I doing wrong?
With grid.Rows(10).Cells
Dim note As New Note With {.ID = "Blah", _
.Date = "1/1/2011", _
.Message = "AAA", _
[code]....
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Jun 23, 2010
I have been trying to create a custom control based on the ListBox called FileListBox. I followed Microsoft's walkthrough but am having some trouble.
What I want is to add another property to the ListBox called SafeItems which is an ObjectCollection of strings (like the Items property). I will use the Items property to store a collection of Filenames as strings and I would like to store the corresponding SafeFilenames in the SafeItems collection.
This is what I've tried:
FileListBox.Designer.vb
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class FileListBox
Inherits System.Windows.Forms.ListBox
[Code].....
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Feb 27, 2012
I have some code I inherited which has a lot of warnings that I would like to get removed. Many are of the form Property '<propertyname>' doesn't return a value on all code paths. I know why it is saying this, I'm just trying to determine what the correct 0 impact way of fixing this is.[code]Unfortuantely if I put this in my code (having changed the local variable name to avoid collisions) it then complains that it is being used before it has been assigned a value.Try to analyze IL in LinqPad (not sure if this is a good test or not) reveals that the empty method is the same as the above that Reflector gave me but it is different from return Nothing and return "".What can I use to get rid of this warning while guaranteeing the code runs 100% the same? [code]I'm not sure what ldloc.0 does here. I'm wondering if it is trying to get something from a register which will be null and if that is therefore the same as ldnull in this situation but I havent' ever really studied IL much before...
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