C# - Iterate Through The Member Variables Of An Object?
May 14, 2011
I'm building a litle console app that involves a control hierarchy -- there are screens, and inside of screens you can compose controls together.
You can add controls to a screen by declaring member variables (which all inherit from AresControl). The control constructor takes a simple coordinate pair. It looks like this:
Public Class IntroScreen : Inherits AresScreen
'Controls
Private LabelSelect As New LabelControl(72, 0)
[Code]....
This would result in cleaner, convention-based code. But try as I might, I can't get it to work - I can walk the member variables of a type, but I need to walk the member variables of a live object.
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Jun 12, 2010
I have created a class called 'MyAddress' and in the form load event i am adding few objects of that class to the combobox. I want to know how should i set and read the values of the member variables of that selected item of the combobox. I have tried this and is working, but i am not sure whether it is the way to do
vb
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[code].....
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Dec 15, 2011
I'd like to have something like:
[Code]...
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Mar 23, 2011
I'm debuging an complex calculation object in my project, and I'd like to show its various and many properties in a textbox, to make my tests easier.
Can I do something like
for each p as someKindOfProperty in MyObject1
debug.print(p.name & " - " & debug.print p.value)
textbox1.text = textbox1.text & vbcrlf & p.name & " - " & p.value
next
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Aug 20, 2010
I read somewhere that interfaces can have member variables.Static final constants only, can use them without qualification in classes that implement the interface. On the other paw, these unqualified names pollute the namespace. You can use them and it is not obvious where they are coming from since the qualification is optional.
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Aug 6, 2010
Here is the structure that I have:
Friend Class StandardFormatFile
Friend fileType As String
Friend numberOfSeries As Integer
[code].....
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Sep 1, 2009
I'm trying to create an export Excel/CSV function that will iterate through a custom object and first output the property names and then output the values. I want to use reflection only where necessary so I'm attempting to save the property names when I output the headers and then reuse them to print the values. Is this possible? I'm a little weary of using reflection in a loop but is there a better way?
[Code]...
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Jun 9, 2010
I am generally not one to engage in subjective arguments over matters like variable naming, code formatting, etc. So I have no intention of starting an argument here.I just came across this (old) blog post which recommends not prefixing member variable names:
[Code]...
I get it: member variables can be lower camelCase, and public properties/methods can be PascalCase. But VB.NET is case-insensitive, so you can't really give a private member the same name as a public property except with a lower case first letter.I've generally prefixed member variables with an underscore, but I've been told that's not idiomatic.
So really I'm just curious: how do you name your member variables in VB.NET? And is there a "standard" way?
I'm not asking because I believe there's a "right" way or because I particularly want to change my style, and certainly not because I have any desire to tell others they're "wrong." Like I said, I'm just curious.
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Oct 12, 2010
How should I handle events in this situation I have "Class1" with a "PropertyHasChanged" event.In "Class2" I've declare a Public Member Variable WithEvents of Type Class1.As well, Class2 has the Event "OtherPropertyHasChange".In a Form Class I've declare a Public Member Variable WithEvents of Type Class2.The Form Member has access to the "OtherPropertyChange" Event but not the "PropertyHasChanged" Event.Question is,how do I accesss the Events of Class1 from the Form Class?
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Apr 25, 2009
I have a VB.NET project where I am able to iterate through the keys and values collections of a dictionary object using an index:
MyDictionary.Keys(idx)
MyDictionary.Values(idx)
When this code is taken from the test project and placed into the real project I get the following error:
'System.Collections.Generic.Dictionary(Of Double, String).KeyCollection' cannot be indexed because it has no default property.[code]...
In the line in sub search that says "dtf.Keys(idx) = 0" place your cursor after the right parenthesis and backspace you should get a tooltip that says, "<Extension> ElementAtOrDefault(index as Integer) as Double - index: the zero based element of the index to retrieve.
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May 27, 2010
How should class member variables be used in combination with class methods?Let's say I have a class 'C' with a member variable 'someData'.I call C.getData(), which does not return a value but instead puts data in C.someData. The class that instantiated 'C' first calls C.getData and then uses the data by accessing the member variable C.someData.I call C.getData() in the class that instantiated 'C' which is a function that returns data.I myself prefer the second way. But it also depends on the situation and it's a small difference. Is it 'bad' to have class methods that depend on the classes internal state? What are the best conventions?
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Sep 11, 2009
I wonder if anyone can help me - I've not done much with reflection but understand the basic principles.What I'm trying to do:I'm in the process of developing a class that gathers a lot of information about the local system, network, etc... to be used for automated bug reporting. Instead of having to change my test harness every time I add a new property, I'd (ideally) like to be able to serialise the lot as an XML string and just display that in a textbox.
Unfortunately, the Framework won't use the default XML serializer on read-only properties (which almost all of mine are) as they wouldn't deserialize properly [Not sure I agree with the assumption that anything serialized must be de-serializable - MS says this is a feature "by design" which I suppose I can understand - Perhaps a tag to indicate that it should be serialized anyway would be advantageous?]
The initial approach was to make properties gettable and settable (with a throw exception on the setter) but the amount of work tidying this up afterwards seems a little excessive and I would want the properties to be read-only in the final version.What I need help with:My current plan is to use reflection to recursively iterate through each (public) property of my topmost gathering class. The problem is, the samples I've seen don't handle things recursively. Additionally, I only want to inspect an object's properties if it's in one of my assemblies - Otherwise just call .ToString on it.
If I don't have the inspection limited to my assembly, I assume I'll get (say) a string which then contains a Length which in turn will have .Tostring method.For the purposes of this project, I can almost guarantee no circular references within my code and as this will only be used as a development tool so I'm not too concerned about it running amok now and then.
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Jun 6, 2011
I am currently making a server monitoring application that pings the server to check its uplink, so far it creates all the picture boxes and labels for each server, and then pings the server, although I have a picture that I want to change dependant on the result.
Below is the code I am currently using, the problem occurs with the objectname variable which allows dynamic coding, where i get a error, saying that "Public member 'image' on type 'String' not found".
Private Sub Ping()
Dim i As Integer
Dim objectName As System.Object
For i = 1 To count - 1
[code].....
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Jun 2, 2011
how do I overcome it? I have created a class and compiled into .dll This code
[Code]...
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Aug 13, 2009
In Visual Studio 2008, if I do this:
[Code]....
Does anyone here know how to get the above to work WITHOUT warnings being generated?
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May 31, 2010
In the following code i get a warning at line 59:Warning 1: Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated.and.. At line 78 I get this Warning:
Warning 2 Property 'SelectedCustomer' doesn't return a value on all code paths. A null reference exception could occur at run time when the result is used.
The program compiles and runs well, but i cant' undesrtand the reason for these warnings. Any Idea ?
1: Public Class Form1
2:
3: 'Form level members
4: Private objCustomers As New ArrayList
[code]....
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Mar 10, 2010
I've got 3 forms that have exactly the same functions, so I decided to create an interface.
public Interface IExample
public sub Add()
Public sub Edit()
[code]....
At this point, objfrmExample is now instantiated, even though I've not done a "objfrmExpample = new [what-goes-here?] " and I'm curious as to why.I could possibly guess that because you cannot instantiate an interface variable, then vb.net automatically creates an instance. But thats just a guess. The question is , what is meant by declaring a variable of type Interface, and how does it work?
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Apr 28, 2011
Cannot appear to be able to get this function to not have the above error.Private Function GetIncidentActions(ByVal FromAgentID As Integer, ByVal ToAgentID As Integer, ByVal incidentAction As Integer, ByVal ActionDate As Date) As String
[Code]...
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May 29, 2010
I have a routine that accepts a List of Objects, a property name and a value to search for and simply returns whether or not it found it.The code I have hangs up at the For loop in the findit routine.[code]
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Nov 29, 2009
I'm writing a Generic for LINQ to SQL CUD. I
'Generic Insert
Public Shared Sub Add(Of T As Class)(ByVal entity As T)
Using db As New APIUDataContext()
[code]....
Error message from Generic Update.Value of member 'Id' of an object of type 'TestAuthor' changed.A member defining the identity of the object cannot be changed.Consider adding a new object with new identity and deleting the existing one instead.What do I need to modify the Generic Update?
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Apr 29, 2009
I was trying to make a reference with a constant but of course I can't do that and before hand I get this error "Refrence to a nonshare member requires an object references" But umm I know I need to make an instance but I really am confused how for the construct. Here is my code: THis is just the class
Public
Class Information
Private CarsDecimal
As
[Code]....
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Nov 16, 2011
I have a combo box that is populated with a list of objects (corresponding to all employee rows from a database that meet the criteria IsTech). These are not entity objects though, I have created my own class that stores the member values of each row from the DB. I have set the DisplayMemberPath to EmployeeId so the Combo box display the EmployeeId ( an integer ) member of my object. Ie. right now there are only 2 IsTech employees in my DB so the combobox displays the numbers 3 and 8 ( their EmployeeIDs).
[Code]...
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Jun 22, 2009
I'm not sure if I'm going mad, it's always a possibility. But is it possible to call a shared member of a class given its 'System.Type' object?
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Nov 30, 2011
I have a function that will be passed an object that contains MANY variables. These variables all get stored in a database. Later a new object will be passed to my function and most of the time it will be identical. But sometimes one or two variables will be different and I'll have to take various actions based on those changes. Other than looping through every variable and comparing it to every stored version of that variable, how might I do this? Can I some how generate a hash value for an entire object? Since the object will be the same most if the times it is passed to me this would be a quick way to determine that nothing has changed.
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Oct 10, 2010
I want to make my own xml-serializer class because I need other formatting than the System.Xml.Serialization.XmlSerializer does. My idea is to treat properties of primitive type (such as Integer, Double, String) as XmlAttributes.To properly implement a usable Xml-Serialization I need to know which variables point to the same object (the binary serialization behaves this way). Because one object should be serialized only once in order that the connections don't get lost.On the side of XmlSerialisation I have the idea to insert a path to the class as a special XmlAttribute.
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Aug 10, 2010
I am writting a VB .net (3.5) applivcation which references a COM object. I can call methods on the COM object fine provided that they don't require any variables to be passed. I have been told that you can only pass a maximum of one varaible to a COM object, I really don't believe that it true
for example
objsession.connect()
works fine
but
[Code]...
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Oct 6, 2008
This is my first post here at Xtreme VB Talk. I just started programming 2 semesters ago. I am currently working on a program but I am having a little trouble with the length. I am trying to take the integer entered in a text box and using it inside the name of another object.
[Code]...
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Jun 12, 2011
I am trying to figure out how to use variables to define which object to update. I could of course use a case statement to pick the object based on a variable, but it seems to me like there should be a more direct way. Here is a smaller example of what I would like to do.In my form I have 4 picture boxes (pbox1, pbox2, pbox3, and pbox4). I then want to change the image in one of the boxes, but the box I want to change will be determined by a variable (say maybe a randomly generated number). Is there some way to dynamically concatenate the "pbox" with the number that VB would understand it and use it as an object?In this example I could easily build a case statement to handle the selection, but in my real program there will be many more than 4 options.
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Jun 18, 2009
project i'm working on for school. Need to make a grade calculator thing but I'm trying to make my code more efficient.
This is what I have at the moment:
txtID.Text = ListBox1.SelectedIndex
txtFname.Text = namesarr(ListBox1.SelectedIndex, 0)
[code].....
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Jan 12, 2012
I have got this error No default member found for type 'VB$AnonymousDelegate_0(Of SqlDataReader,String,Object)'.
My Code is below
dsBranch.Tables.Add(GetDataTableFromSQLReader(dr, "")) - Calling
Private Function GetDataTableFromSQLDataReader(ByVal dr As SqlDataReader, ByVal TableName As String)
[code]....
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