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  • How to infer the type of a derived class in base class?

    - by enzi
    I want to create a method that allows me to change arbitrary properties of classes that derive from my base class, the result should look like this: SetPropertyValue("size.height", 50); – where size is a property of my derived class and height is a property of size. I'm almost done with my implementation but there's one final obstacle that I want to solve before moving on, to describe this I will first have to explain my implementation a bit: Properties that can be modified are decorated with an attribute There's a method in my base class that searches for all derived classes and their decorated properties For each property I generate a "property modifier", a class that contains 2 delegates: one to set and one to get the value of the property. Property Modifiers are stored in a dictionary, with the name of the property as key In my base class, there is another dictionary that contains all property-modifier-dictionaries, with the Type of the respective class as key. What the SetPropertyValue method does is this: Get the correct property-modifier-dictionary, using the concrete type of the derived class (<- yet to solve) Get the property modifier of the property to change (e.g. of the property size) Use the get or set delegate to modify the property's value Some example code to clarify further: private static Dictionary<RuntimeTypeHandle, object> EditableTypes; //property-modifier-dictionary protected void SetPropertyValue<T>(EditablePropertyMap<T> map, string property, object value) { var property = map[property]; // get the property modifier property.Set((T)this, value); // use the set delegate (encapsulated in a method) } In the above code, T is the Type of the actual (derived) class. I need this type for the get/set delegates. The problem is how to get the EditablePropertyMap<T> when I don't know what T is. My current (ugly) solution is to pass the map in an overriden virtual method in the derived class: public override void SetPropertyValue(string property, object value) { base.SetPropertyValue((EditablePropertyMap<ExampleType>)EditableTypes[typeof(ExampleType)], property, value); } What this does is: get the correct dictionary containing the property modifiers of this class using the class's type, cast it to the appropiate type and pass it to the SetPropertyValue method. I want to get rid of the SetPropertyValue method in my derived class (since there are a lot of derived classes), but don't know yet how to accomplish that. I cannot just make a virtual GetEditablePropertyMap<T> method because I cannot infer a concrete type for T then. I also cannot acces my dictionary directly with a type and retrieve an EditablePropertyMap<T> from it because I cannot cast to it from object in the base class, since again I do not know T. I found some neat tricks to infere types (e.g. by adding a dummy T parameter), but cannot apply them to my specific problem. I'd highly appreciate any suggestions you may have for me.

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  • How do I create a generic method with a generic in the where clause? (Man that's clear as mud!)

    - by Jordan
    Is there a way of doing this: protected void SubscribeToEvent<TEvent, TPayload>(Action<TPayload> a_action) where TEvent : CompositePresentationEvent<TPayload> { TEvent newEvent = _eventAggregator.GetEvent<TEvent>(); SubscriptionToken eventToken = newEvent.Subscribe(a_action); _lstEventSubscriptions.Add(new KeyValuePair<EventBase, SubscriptionToken>(newEvent, eventToken)); } without requiring the user to specify a TPayload parameter?

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  • What are the different methods for injecting cross-cutting concerns?

    - by Stacy Vicknair
    What are the different methods for injecting cross-cutting concerns into a class so that I can minimize the coupling of the classes involved while keeping the code testable (TDD or otherwise)? For example, consider if I have a class that requires both logging functionality and centralized exception management. Should I use DIP and inject both required concerns via an interface into the class that requires them? Should I use a service locater that I pass to each class that will require some cross cutting functionality? Is there a different solution altogether? Am I asking the wrong question entirely?

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  • Is it possible to create custom methods in entity classes in linq to sql

    - by doekman
    I have a table Site in SQL with (amongst others) three properties idReviewer1, idReviewer2, idReviewer3. Now I would like to create a methods on the entity class of Site to check if a user is a reviewer: partial class Site { public bool IsReviewer(int idUser) { return idReviewer1 == idUser || idReviewer2 == idUser || idReviewer3 == idUser; } } and I use it like this: return from s in db.Sites where s.IsReviewer(user) select s; However, Linq to SQL doesn't know how to translate this to SQL. I get the following error message: Method 'Boolean IsReviewer(Int32)' has no supported translation to SQL. I'd rather not write this: return from s in db.Sites where idReviewer1 == idUser || idReviewer2 == idUser || idReviewer3 == idUser select s; Is there any way to put this functionality in one place, without resorting to SQL?

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  • Java Webservice with generic methods

    - by danby
    Hi, I was wondering if it is possible to make a generic webservice method in java like this: @WebMethod public <T extends Foo> void testGeneric(T data){ However when I try to consume this with a Java client I get an error stating: [ERROR] Schema descriptor {http://####/}testGeneric in message part "parameters" is not defined and could not be bound to Java. I know it is possible to make a method that takes a parameter such as List and this generates correctly using JAX-WS. I don't mind if there is a solution that means I am tied to using only a particular technology. Thanks, Dan.

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  • Using Public/Private keys in reverse

    - by Wizzarding
    Hi, I have a situation where I need to make some data available for reading by anyone from a specific device, where the data is pre-loaded on the device, but I cannot allow anyone to create their own device and populate it with their own data in the same format. I know this sounds a little crazy, but there is a good reason! I was planning to use Public Key cryptography, encrypting the data with a public key, but then publishing the private key to anyone who wants to read the data. However, after looking at the RSACryptoServiceProvider and how it works it looks like I cannot just publish the private key as the private key can be used to create the public key. Could someone confirm that suspicion, or give me some hints on how I might be able to make this work! Many Thanks.

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  • Is it weird or strange to make multiple WCF Calls to build a ViewModel before presenting it?

    - by Nate Bross
    Am I doing something wrong if I need code like this in a Controller? Should I be doing something differently? public ActionResult Details(int id) { var svc = new ServiceClient(); var model = new MyViewModel(); model.ObjectA = svc.GetObjectA(id); model.ObjectB = svc.GetObjectB(id); model.ObjectC = svc.GetObjectC(id); return View(model); } The reason I ask, is because I've got Linq-To-Sql on the back end and a WCF Service which exposes functionality through a set of DTOs which are NOT the Linq-To-Sql generated classes and thus do not have the parent/child properties; but in the detail view, I would like to see some of the parent/child data.

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  • How do you handle ajax requests when user is not authenticated?

    - by LukLed
    How do you handle ajax requests when user is not authenticated? Someone enters the page, leaves room for an hour, returns, adds comment on the page that goes throuh ajax using jQuery ($.post). Since he is not authenticated, method return RedirectToRoute result (redirects to login page). What do you do with it? How do you handle it on client side and how do you handle it in controller?

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  • Linq-to-XML explicit casting in a generic method

    - by vlad
    I've looked for a similar question, but the only one that was close didn't help me in the end. I have an XML file that looks like this: <Fields> <Field name="abc" value="2011-01-01" /> <Field name="xyz" value="" /> <Field name="tuv" value="123.456" /> </Fields> I'm trying to use Linq-to-XML to get the values from these fields. The values can be of type Decimal, DateTime, String and Int32. I was able to get the fields one by one using a relatively simple query. For example, I'm getting the 'value' from the field with the name 'abc' using the following: private DateTime GetValueFromAttribute(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == "abc" select (DateTime)field.Attribute("value")).FirstOrDefault() } this is placed in a separate function that simply returns this value, and everything works fine (since I know that there is only one element with the name attribute set to 'abc'). however, since I have to do this for decimals and integers and dates, I was wondering if I can make a generic function that works in all cases. this is where I got stuck. here's what I have so far: private T GetValueFromAttribute<T>(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == attName select (T)field.Attribute("value").Value).FirstOrDefault(); } this doesn't compile because it doesn't know how to convert from String to T. I tried boxing and unboxing (i.e. select (T) (Object) field.Attribute("value").Value but that throws a runtime Specified cast is not valid exception as it's trying to convert the String to a DateTime, for instance. Is this possible in a generic function? can I put a constraint on the generic function to make it work? or do I have to have separate functions to take advantage of Linq-to-XML's explicit cast operators?

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  • Is a Multi-DAL Approach the way to go here?

    - by Krisc
    Working on the data access / model layer in this little MVC2 project and trying to think things out to future projects. I have a database with some basic tables and I have classes in the model layer that represent them. I obviously need something to connect the two. The easiest is to provide some sort of 'provider' that can run operations on the database and return objects. But this is for a website that would potentially be used "a lot" (I know, very general) so I want to cache results from the data layer and keep the cache updated as new data is generated. This question deals with how best to approach this problem of dual DALS. One that returns cached data when possible and goes to the data layer when there is a cache miss. But more importantly, how to integrate the core provider (thing that goes into database) with the caching layer so that it too can rely on cached objects rather than creating new ones. Right now I have the following interfaces: IDataProvider is used to reach the database. It doesn't concern itself with the meaning of the objects it produces, but simply the way to produce them. interface IDataProvider{ // Select, Update, Create, et cetera access IEnumerable<Entry> GetEntries(); Entry GetEntryById(int id); } IDataManager is a layer that sits on top of the IDataProvider layer and manages the cache interface IDataManager : IDataProvider{ void ClearCache(); } Note that in practice the IDataManager implementation will have useful helper functions to add objects to their related cache stores. (In the future I may define other functions on the interface) I guess what I am looking for is the best way to approach a loop back from the IDataProvider implementations so that they can access the cache. Or a different approach entirely may be in order? I am not very interested in 3rd party products at the moment as I am interested in the design of these things much more than this specific implementation. Edit: I realize the title may be a bit misleading. I apologize for that... not sure what to call this question.

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  • whatz wrong in this SELECt query of MSSQL... ?

    - by user522211
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Dim SQLData As New System.Data.SqlClient.SqlConnection("Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True") Dim cmdSelect As New System.Data.SqlClient.SqlCommand("SELECT * FROM Table1 WHERE Date =" & TextBox1.Text & "'", SQLData) SQLData.Open() Dim dtrReader As System.Data.SqlClient.SqlDataReader = cmdSelect.ExecuteReader() While dtrReader.Read() For j As Integer = 1 To 31 Dim s As String = "s" & j If dtrReader(s.ToString()).ToString() = "b" Then Dim img As ImageButton = DirectCast(Panel1.FindControl(s.ToString()), ImageButton) img.ImageUrl = "~/Images/booked.gif" img.Enabled = False End If Next End While dtrReader.Close() SQLData.Close() End Sub SHOWS AN ERROR : Unclosed quotation mark after the character string ''.

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  • Generic TypeIdenitifier convertion.How?

    - by John
    How do I convert the TypeIdenitifier to a class type? I need to use implicit convertion. type TMyChildArray<T>=class(TMyArray<T>) private FData:Array of T; procedure AddEnd(); end; TTypeIdenitifierParentClass=class(TAnotherParentClass) protected TestField:Cardinal; end; procedure TMyChildArray<T>.AddEnd(); var elem:T; begin for elem in Fdata do TTypeIdenitifierParentClass(elem).TestField:=0; end; I get "Invalid typecast" on the implicit convertion "TTypeIdenitifierParentClass(elem).TestField:=0;". The principle I want to use is that the TypeIdenitifier will represent a class that descends from TTypeIdenitifierParentClass.There are many class types,but all of them descend that class. How do I do this?

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  • implementing security with session variables, how it is insecure

    - by haansi
    I am doing web based projects in dotnet. Currently I am implementing security using session variables. I keep current user id and user type in session and authenticate user from these session variables (say Session["UserId"],Session["UserName"] and Session["UserType"]). Please help me understand how this could be insecure. I've heard that such security can be broken and applications can be hacked very easily, like it is possible to get session id and directly connect to that session id etc. Please guide me on this.

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  • Java generic return tpye

    - by Colby77
    Hi, I'd like to write a method that can accept a type param (or whatever the method can figure out the type from) and return a value of this type so I don't have to cast the return type. Here is a method: public Object doIt(Object param){ if(param instanceof String){ return "string"; }else if(param instanceof Integer){ return 1; }else{ return null; } } When I call this method, and pass in it a String, even if I know the return type will be a String I have to cast the return Object. This is similar to the int param. How shall I write this method to accept a type param, and return this type?

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  • Forcing EditorFor to prefix input items on view with Class Name?

    - by Kohan
    I have an EditorFor: <%: Html.EditorFor(model => model.Client, "ClientTemplate", new { editing = false })%> This will bind coming down to the view fine (as expected) but will not bind bind back when the model gets posted. This is due to the form id's not being prefixed with "Client." Usually in this situation i just pass in model and then bind the inputs to model.Client.PropertyName in the Template but this is not an option in this case as the template is used on two different viewmodels (that have client on). Any suggestions on getting this to bind properly? Many thanks, Kohan.

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  • sql server - framework 4 - IIS 7 weird sort from db to page

    - by ila
    I am experiencing a strange behavior when reading a resultset from database in a calling method. The sort of the rows is different from what the database should return. My farm: - database server: sql server 2008 on a WinServer 2008 64 bit - web server: a couple of load balanced WinServer 2008 64 bit running IIS 7 The application runs on a v4.0 app pool, set to enable 32bit applications Here's a description of the problem: - a stored procedure is called, that returns a resultset sorted on a particular column - I can see thru profiler the call to the SP, if I run the statement I see correct sorting - the calling page gets the results, and before any further elaboration logs the rows immediately after the SP execution - the results are in a completely different order (I cannot even understand if they are sorted in any way) Some details on the Stored Procedure: - it is called by code using a SqlDatAdapter - it has also an output value (a count of the rows) that is read correctly - which sort field is to be used is passed as a parameter - makes use of temp tables to collect data and perform the desired sort Any idea on what I could check? Same code and same database work correctly in a test environment, 32 bit and not load balanced.

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  • 398 row datalist slowing down modal open????

    - by Jreeter
    Hey guys I got a weird issue.. I have a datalist that's only loaded on pageload it contains 2 columns a name and date and has 398 rows.. In IE 7 and above(and prob previous version) when I open a modal via a button click it takes almost 5 seconds to open. HOWEVER, if I do not bind this datalist it's MUCH faster.. Also this is only happening in IE, Chrome, Firefox and opera both open the modal instantly with the datalist binded... Josh

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  • Multiple generic types in one container

    - by Lirik
    I was looking at the answer of this question regarding multiple generic types in one container and I can't really get it to work: the properties of the Metadata class are not visible, since the abstract class doesn't have them. Here is a slightly modified version of the code in the original question: public abstract class Metadata { } public class Metadata<T> : Metadata { // ... some other meta data public T Function{ get; set; } } List<Metadata> metadataObjects; metadataObjects.Add(new Metadata<Func<double,double>>()); metadataObjects.Add(new Metadata<Func<int,double>>()); metadataObjects.Add(new Metadata<Func<double,int>>()); foreach( Metadata md in metadataObjects) { var tmp = md.Function; // <-- Error: does not contain a definition for Function } The exact error is: error CS1061: 'Metadata' does not contain a definition for 'Function' and no extension method 'Function' accepting a first argument of type 'Metadata' could be found (are you missing a using directive or an assembly reference?) I believe it's because the abstract class does not define the property Function, thus the whole effort is completely useless. Is there a way that we can get the properties?

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  • RequireHttpsAttribute and Encrypted Request Data

    - by goatshepard
    I have a controller action that is accepting sensitive data. public ActionResult TakeSensitiveData(SensitiveData data){ data.SaveSomewhere(); } To ensure the data is secure I want to be certain requests are made using HTTPS (SSLv3, TLS 1). One of the approaches I've considered using was the RequireHttpsAttribute on my action: [RequireHttps] public ActionResult TakeSensitiveData(SensitiveData data){ data.SaveSomewhere(); } However, upon testing this I fiddler revealed that an HTTP request made to the action is 302 redirected to HTTPS. My question is this: If I've made a request that is 302 redirected to HTTPS haven't I already sent the sensitive data over HTTP before the redirect?

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  • Where are the function literals c++?

    - by academicRobot
    First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one.

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