.net - Storing An Object To Use In Multiple Classes?
Mar 23, 2010
I am wondering the best way to store an object in memory that is used in a lot of classes throughout an application. We have multiple databases, 1 per customer. We also have a master table and each row is detailed information about the databases such as database name, server IP it's located and a few config settings.
I have an application that loops through those multiple databases and runs some updates on them. The settings I mentioned above are updated each loop iteration into memory. The application then runs through series of processes that include multiple classes using this data. The data never changes during the processes, only during the loop iteration.
The variables are related to a customer, so I have them stored in a customer class. I suppose I could make all of the members shared or should I use a singleton for the customer class? I've never actually used a singleton, only read they are good in this type of situation. Are there better solutions to this type of scenario? Also, I could have plans for this application to be multithreaded later.
In .net, it's possible to use generics so that a function can accept arguments which support one or more interfaces and derive from a base type, even if there does not exist any single type from which all valid argument types derive. For example, one could say: Sub Foo(Of T As {IInterface1, IInterface2, SomeBaseType})(Param as T) And be allowed to pass any derivative of SomeBaseType which implements both IInterface1 and IInterface2. This will work even if SomeBaseType does not support Interface1 and Interface2, and classes which do implement those interfaces don't share any common ancestor that also implements them. This can be very convenient if one won't need to keep the parameter anywhere after the function has exited. Unfortunately, I can't figure out a way to persist the passed-in parameter in such a way that it can later be passed to a similar function, except perhaps by using Reflection. Is there any nice way of doing that?
The closest I've been able to come up with is to define an interface INest (perhaps not the best name-- thus:
Interface INest(Of Out T) Function Nest() As T End Interface
And for any interface that will be used in combination with others or with base-class "constraint", define a generic version as illustrated below:
Interface IFun1 ' Any members of the interface go here, e.g. ...' Sub DoFun1()
[CODE]...
A class which will support multiple interfaces should declare itself as implementing the generic ones, with itself as the type argument.
Class test123a Inherits sampleBase Implements IFun1(Of test123a), IFun2(Of test123a), IFun3(Of test123a) End Class
If that is done, one can define a function argument or class variable that supports multiple constraints thusly: Dim SomeField as IFun1(Of IFun2(Of IFun3(Of sampleBase)))
And then assign to it any class derived from sampleBase, which implements those interfaces. SomeField will implement IFun1; SomeField.Nest will implement IFun2; SomeField.Nest.Nest will implement IFun3. Note that there's no requirement that IFun1, IFun2, IFun3, or sampleBase share any common derivation other than the generic interfaces inheriting from INest(Of T). Note also that, no matter how many INest-derived interfaces a class implements, it only needs to define one implementation of INest(Of T).Nest. Not exactly beautiful, but there are two nice things about it: (1) any concrete class which in fact implements the necessary interfaces can be assigned directly to a field declared as above, without a typecast; (2) while fields which chain the types in a different order are not assignment compatible, they may be typecast to each other. Is there any better way to store something in such a way that it's "known" to support multiple interfaces and derive from a certain base type? Given that one can write such code in a type-safe manner, it would seem like the .net 2.0 CLR could probably support such a thing quite nicely if compilers offered a little assistance.
I was looking through some legacy code we have and I noticed something that struck me as particularly odd.Say we have the concrete class TestClass. TestClass implements the interface ITestClass.What sort of behavior should I expect in the following case, then? (I didn't realize this was even possible)
Dim testClass as TestClass = Nothing Try testClass = New ITestClass
I have propetie get set classes, and a constructor to quickly set them all.The only concern I have is that the byval in the constructor class and the byval in the set() properties, might be inefficient because the parameter is copied twice? Should I use ByRef? Or is that too dangerous?
'Config data for an Environment. Public Class Environment Private msEnvName As String
In Java you can store a class in a separate file and instantiate it from a method in another file as long as the class file is in the same directory but this doesn't seem to work in Visual Basic.
I am at a new company and I am building a wizard for a web app, (.Net/4.0). The user goes to a few separate screens during the wizard process and must return to the original screen before completion of the wizard. This is different from how they normally do this. But this is how it is TO BE DONE.
One option is to store the result of each panel in the main screen in the DB. So then, when the user leaves & redirects back. I could check for a querystring then call a datareader and populate original values appropriately.
My understanding of classes/objects is that you create a class that acts as a "template".From there you simply declare an object of that class and operate directly on that object.eg, object.methods, object.properties etc.That's my limited understanding.I've got a huge form in another project that is crying out for a decent class structure to hold references to a multitude of numbered textboxes.
2)The program needs to access particular chunks(for example (0,20) to (50,20)
3)The program will open multiple files and process each into it's own 2D array (400,20)
What I have right now is code capable of creating the array, but no way to store the array so that I can open a new file and process that data into another large array. Someone mentioned the generics List(of T) might be a good way to store each new array as you could use the Add function. I have done some research on the List(of T) class but I'm not totally convinced that is the way to go. I'm just looking for some direction as I've just started on .net this year.
I'm trying to store three images from a form (PictureBox's) into a SQL Database (MSSQL2008) The below does what I want but is clearly inefficient. Any pointers on what to change to improve this?
Private Sub SaveImages() Dim ConStr As String = "Data Source=SERVERSQL2008;Initial Catalog=NorthPole;Integrated Security=True"
I have a VB2010 application that must run as multiple instances on the same PC (it is a controlling/monitoring program of several devices, each instance of the program control one device)
Of course, the same application must save its own setting in different place, one for each device. For example, if I start the application for the device 3, I have to save the setting in a place marked as "3", in this way, when I start the application for device 4 it will load the settings for device 4 and not 3.
Of course all labels and similar stuffs must refer the starting device: i.e. the mdi caption must report "device 4", and so on...
In vb6 I created a shortcut with a command line and made my application accepting command line parameters.
In this way I could start the application passing the device number too. For example "myapp.exe 3" start my application for the device 3.
I stored all settings in several INI file, each one for a device: setting1.ini, setting2.ini, setting3.ini, ....
I was wondering if in vb2010 would be a better way to do that.
I create a string array from a bunch of files that were dropped on a control after that i use a loops to pass that data into an array of my pictureObjects object (just stores filePath info and some other things).for some reason after it's been passed to the control the "My.Computer.FileSystem.RenameFile" doesn't seem to work at all... it's a valid file name and everthing.
Dim sFileArray() As String = e.Data.GetData(DataFormats.FileDrop)
'load sFileArray into new array of picureObjects ReDim dropedPicture(sFileArray.Length) Dim dropedOnPictureBox As Integer[code]......
I downloaded a .net component that I would like to make consumable by COM clients. This component allows one to create a DXF file (Cad drawing). The problem is that the component is composed of quite a few class files, some inherit another. All the examples I found only show one file no namespaces etc. [Code]
I'm a long-time developer but semi-new to Visual Studio .NET and VB.NET. I've been working on an application for months, written in Visual Basic .NET. It's a rewrite of a popular IDE of mine that's originally written in assembly. What I'm trying to do in VB.NET is have multiple TabPage classes that inherit from TabPage, ofcourse, but each having it's own methods for common functions like Cut, Copy, Paste, etc. so that when I call tab.Cut(), the TabPage class for the currently-selected tab is the one used. In each custom TabPage class, I'll have a New instance of the main control that goes in that tab.
I think there would be a problem when I loop through the TabPages since the Foreach routine can only use one object type, as far as I know (TabPage).Currently I have only one custom TabPage class called Page that obviously inherits from TabPage, has additional properties and also methods that allow editing functions for whatever control is selected to be displayed for the tab. For example, when I call the New constructor, I supply the editor type as a parameter: dim tab as New Page(HEX_EDITOR).I have edit controls such as text, syntax editor, hex editor, bitmap editor, HTML editor, HTML browser. This means I get a new instance of all of those controls each time a new Page is added to the TabControl. I'm currently disposing of the unneeded editors depending on which editor is the one needed. The scheme is not preferred but it works great for now as I work on other areas of the IDE.
I have one class with <Serialize> attribute called Tree. And Tree class has an arraylist of TreeNode classes. Is it possible to use Soap to convert the Tree class and arraylist of TreeNode classes to one xml file or binary file? If it is possible, do i need to use <Serialize> attribute on TreeNode classes too? If not, what should i do then?
all classes inherit docMain and addTemplateToList( X ) adds x to a List(Of docMain). Now my question is: Is there a better way to do what's done in the code sample? I thought of something like:
I am integrating two disparate data sources where each value may depend on one or more other derived elements.This app runs as a windows service.Currently all my code is in a single class.I am upgrading to 2010 and wondering if best practices would be to break out my functions into multiple classes - there are over 100 data elements that need to be constructed. The following is an example of a couple derived items:(Is there a better way to do this - when complete I will pass this app off to someone else to support and want to make sure I give them the best beginning.[code]......
Is it possible to have multiple classes in a namespace and be able to reference the functions within the clases if the Major class is instaniatated from another class?? for instacnce:
Namespace Database Public Class Data Public Class Prepare
I'm still teaching myself how to bind and use observable collection. One problem that I'm a little confused on is binding multiple classes/observable collection to one page. In other words, if I have a PersonName class and a AnimalName class, I have to create two separate observalbe collections for each? How would I set the datacontext when a page only allows one?
[code]...
Now If I add another class, how would I combine the two on the binding part and collection part.
Okay, say I have a class named "ChannelList", and it raises an event named "FoundChannel"
But what I'M wanting to do is create multiple classes of different names that use that class, but I want to have all of the "FoundChannel" events be handled under one single sub routine?
I want to be able to incorporate some constant definitions and enum types in multiple classes of mine.Something akin to including a header file in C++. How do I do this best in VB.NET? I'm having a hard time because the only way I can see to do it is to inherit a class with the definitions in it but there is no multiple inheritance in vb.net so I am having some issues with that.
while making my irc bot i need to send many different irc commands such as join channel, change mode, kick user message, topic channel message and so on. All these commands are currently process individually in a public sub on the irc connection thread.
Public Sub Write(ByVal command As String) _streamWriter.WriteLine(command) _streamWriter.Flush()
[Code]....
Would you have a load of public sub's to handle each or maybe something else?
I'm developing a new functionality for web site project with VB.NET default language in VS 2008. As my preferred language is C# I create subfolder for C# code in the App_Code folder and add appropriate codeSubDirectories element to web.config file. The problem is that I can't refer VB.NET classes in my C# code. All VB.NET classes and structures are placed in global namespace in the App_Code. But even if I place some VB.NET class in the same namespace I've use for my classes in C#, I still can't use them.
I have a serializable Message class that has a Data As Object property that I'm using as a generic holder for information to be sent via a system that uses a combination of push technology and/or IPC to communicate with any other programs that are interested in the information. This allows the communication piece to be agnostic of the information it transmits.
I was serializing this Data As Object as a Byte[], since I was worried about how an Object being serialized and transmitted across the network would behave on the other side. However, when deserializing I get errors about being unable to find the assembly for the types stored within my Data As Object property, because I'm deserializing in the assembly that contains the Message class... not the assembly that contains the type that Data As Object originally was.I was wondering if I'd lose the type information and be unable to cast it back to the type I want at the other end. Perhaps it's not possible to pass a type as an Object via another assembly without it knowing about my type?
