Caching Propertyinfo Of Abstract Class?
Jan 19, 2012
I've been playing around with implementing an abstract base class that using reflection accomplishes SQL to Object mapping.
I did some benchmarks and decided I wanted to implement a caching strategy for the property info of the objects (to prevent future lookups on them). My first instinct was to try and implement something like this.
Public MustInherit Class BaseModel
Implements IFillable
Private Shared PropertyCache As List(Of PropertyInfo)
[Code]....
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Jan 6, 2010
I created a vb.net dll which I am using in an unmanaged c++ project.When I try to create an object of the class, I am getting an error:cannot instantiate abstract class.Why would my class be abstract? How can I modify it so that it won't be abstract?
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Mar 30, 2011
I have one interface that contains four functions. I have about 20 classes that implement this interface. Throughout each class, I see a lot of duplicate code, for example, there are constants declared at the beginning that are in every class. The method implementations (logic) of the interface are mostly the same.It contains duplicate structures. Is this a case where I can eliminate a lot of duplicate classes by implementing an abstract class instead of an interface. What I am striving for is too be able to put common methods from the abstract class as non-abstract methods and then methods that need their own implementation would be marked over-ridable. Can I put consts and structures in abstract classes? If so, that would eliminate a lot of duplicate code across the classes. Is there anything else I should look out for in the classes as a sign that I probably should be use an abstract class instead of an interface.
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Sep 8, 2011
I'd like to make sure each of the subclasses has a certain nested class whose actual fields are up to the developer.
Nesting an abstract class inside the base abs. class doesn't seem to do the trick because during actual coding, both the nested abs. class and the nested class in the subclass both are available (show up in intellisense).
Having the base class implement an interface that includes a class doesn't work since interfaces only refer to methods that can be implemented, not classes (meaning implementing the interface requires implements methods, but says nothing about classes in the interface.
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Jan 31, 2011
understanding difference between an interface and an abstract class which has no function with implementation?which is better abstract cls or interface in term of speed, features..?
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May 13, 2010
I am developing a web app but is not satisfied with is architecture that I am following. The architecture is plain old conventional 3 tier architecture. What i want is follow some design pattern or architecture that will be help me in decoupling my code.I have idea about MVC and MVP architectures for Web App but i need different from that. I want to use OOPS concepts using abstract classes and interfaces, polymorphism etc in my app but not MVC and MVP. I dont know why?
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Mar 4, 2011
explain to me the differences between an abstract class and a class marked MustInherit?
Both can implement shared and instance constructors and logic. Both can/must be inherited.
So why use one over the other and what is the difference?
Edit: Sincerely apologize I have got my languages mixed up. Will mark correct answer as soon as I am allowed.
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Mar 31, 2010
I am trying to compile the following code and i am getting the error[code]...
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Jul 6, 2010
Basically, I have a custom child form class which has events that will be passed to the parent. In the custom child form, I have a declaration of a "MustInherit" class that inherits the DevExpress User Control Class.
The reason for this, is I have many user controls that derive from this base class, and the child form can have an instance of any one of these controls, and doesnt care which. The only requirement is that the child form can handle the same events from each type of control the same way.
Some watered down code snippets(still pretty long unfortunately):
'''Inherited Class
Public Class ChildControlInheritedClass
[Code].....
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Dec 28, 2011
If i have a class called A and a class called B, if B inherits A that means A is the super class and B is the subclass. I have been asked to describe why class A is not an abstract class but as i see it class A is an abstract class A, as it has been created for Class B to use in the future, is it something to do with Class B not being able to access the fields in Class A as although they are private by default?
[Code]...
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Aug 25, 2009
By Default code behind looks like --
Partial Public
Class InhAbs
[code].....
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Nov 19, 2010
I have an abstract class in vb.net with two subclasses. In the abstract class I have a constuctor that looks like this:[code]I would like to create a second constructor that doesn't take any arguments and just initializes the args to default values.[code]When I attempt to create a new subclass using the second constructor the compiler complains that I'm missing two args to the constructor.Is there a reason I can't overload the constructor in the abstract class?
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Jul 5, 2009
What is the difference between a class with protected constructors and a class marked as MustInherit? (I'm programming in VB.Net but it probably equally applies to c#). The reason I ask is because I have an abstract class that I want to convert the constructors to shared/static methods. (To add some constraints). I can't do this because it's not possible to create an instance in the shared function.
[Code]...
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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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Oct 7, 2011
I have recently come across some code that has the following. First there is a Interface with the following function Function Validate() As Boolean. That interface is then implemented in the an 'ABSTRACT' class like this.
Public MustOverride Overloads Function Validate() As Boolean Implements IBusinessEntity.Validate
Question 1: Why use Overloads in the Abstract class implementation.
Question 2: The Abstract class is then inherited into a class (TestClass). In TestClass the Validate function is implemented as follows Public Overloads Overrides Function Validate() As Boolean. I understand the Overrides keyword is to insure that this is the version of the Validate that you want called and not the Abstract class version but why again use the keyword Overloads?
From what I understand you can overload a constructor of a class by simply changing the constructor signature. Also, you overload Methods and Properties of a class by using the Keyword Overloads. But why do it when your implementing an Interface method, or an Abstract Class method that's inherited.
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Oct 15, 2008
Basicly I'm downloading XML files with the Webclient class for processing and caching in a local database. There are three different categories of data, each contains 1 to n numbers of XML files. To retrieve the XML file I ask the server with following parameters in the URL:
[Code]...
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Aug 23, 2005
An argument exception is thrown when attempting to use PropertyInfo.SetValue to set the value of a property in my business objects.The argument is thrown because of wrong data type, even though a valid cast could be made.Is there a way to dynamically cast the object type into the underlying PropertyType of the PropertyInfo object without having to test the FullName property explicitly as show below?
Select Case prop.PropertyType.FullName
Case "System.String"
prop.SetValue(obj, tbx.Text, Nothing)
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Feb 15, 2010
I have an abstract class which requires a delegate to function. I pass the delegate into the constructor. Now that I have a non default constructor I need to call the abstract class's constructors from the concrete class which means that I need to use MyBase.New(...). I have included a quick example below.
Public MustInherit Class BaseClass
Public Delegate Sub WorkMethod()
Private _Work As WorkMethod
[code]....
I have tried to do this but I keep getting the following error: "Implicit reference to object under construction is not valid when calling another constructor".Can I not do what I am trying to do above? I initially had the delegate setup in its own setter method. But then I am creating a deceptive API because it does require a point to a method to work properly.
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Sep 16, 2010
I currently have a control that called MyGridview that inherits Gridview. It has a paging template within it for customized paging options, and I'm at the point where I want to cache the initial datasource for better performance.I haven't done this in a long time, so perhaps there is a different solution these days with the newer frameworks.Before, I simply used a Cache object that was named whatever the gridview was named. I couldn't use the same gridview name through the application though.Is there a best way to have a cache object, or some other object like a session within the control to store those unique datasets for paging and sorting?
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Jan 8, 2010
I'm pulling data from a Lotus Notes database, this works fine but when I change the data and pull it again, it doesn't take the changes, a restart solves this so it must be getting cached somewhere, how do I prevent it?[code]...
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Jul 27, 2009
Is it possible to cache dataset which is accessible globally.Example: One windows service creates a dataset and caches it.Another Web Application and Windows application references that cache and populates in datagrid.
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May 14, 2012
I need to implement caching in Asp.net web application My need to store data with different ID's. So which method is better ?
Use a dictionary variable. Insert the data (key as ID and data as value).
Dim mDict As New Dictionary(Of String, String)
mDict .Add(bID, uwtTree.WriteXmlString(True, True))
Cache.Insert("mTree", mDict)
[Code]....
Which method is the best way ? Or is there any other method exists ? I am using .Net 3.5 /IIS 7 (VB.Net).
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Jul 5, 2010
Is there a way to disable asp.net caching on selected page. It would be nice if this can be done from the web.config.
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Feb 24, 2011
I'm having a http handler that is retrieving images from the file system on the server. I need to cache these images on the client side(browser). For that thing i'm doing the following code
context.Response.Clear()
context.Response.ClearHeaders()
context.Response.ClearContent()
[Code].....
The thing happening with this is ... When i switch between the tabs its taking it from the cache... but when i hit the browsers refresh button its again going to the file system on the server. how to cache these images on the client side.
P.S: Cant do markup caching for all the pages im my application.
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Aug 6, 2010
I have been googling for hours and trying to figure this out, and I just can't.I have 1 webbrowser control on a form, webbrowser1. Once I load a page, say google.com, if I use webbrowser1.refresh() or webbrowser1.navigate("google.com"), it's not reloading the page, it has it cached so it's just reloading the cache. This is terribly apparent especially on pages like forums or craigslist.
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Mar 19, 2012
I've tried applying several suggestions found on the web, but still experiencing cached results when querying CRM 2011 with linq. My web.config reads as follows, which is supposed to disable result caching:[code]I can live with that, but it would be nicer, instead of recreating the context, to have a way of ensuring no caching either in code or in web.config.
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Sep 29, 2010
I'm not sure I wrote the headline right, but I've got a service that holds a password in memory. It's notification thing, and so will be running 24/7 ideally.
It uses a password to some other resources that I send to it at startup in a UPD packet.
I'd like to find a way to instruct windows never to stick that value in the disk cache so if the worst happened, the theoretical bad guy couldn't pick apart the cache and find the password.
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Nov 19, 2011
I'm making a webbrowser for the pc's on my school, but I want to clear cache & clear cookies everythime someone exit's the webbrowser. Is there a simple code for it?
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Oct 5, 2009
A quick question on caching dataset objects. How can I know if the data is changed in Sql when caching data? I don't want to specify time constraints but used a strategy where data is changed in sql and I have to refresh my cache?
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Feb 27, 2009
We have data that's updated nightly in a database residing in the same instance as my app's database. So to save on database calls, I want to cache this static-for-the-day data into a List(Of MyObject). From a theory point of view, should this cached List(Of ) be cached in the presentation layer code, via a global variable? Should it be in a global variable in the .DLL?I'm thinking in the .DLL, because I created a service layer, which is exposed publicly to the GUI and makes calls to the data access layer inside the .DLL:
Public Shared Function Search(ByVal criteria As Core.Other.Customer) As List(Of Core.Other.Customer)
' TODO: Check the customer cache to see if it has been populated yet. If not, populate it.
If 1 = 1 Then
[code]....
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