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  • What are the disadvantages of using a StringBuilder?

    - by stickman
    I know that StringBuilder is more efficient than a normal string when processing code which modifies the string value a lot because although strings act like value types, they are actually reference, which makes them immutable so every time we change it, we need to create a new reference in memory. My question is that, why doesn't .NET just use stringBuilder by default? There must be some disadvantages of it over just using String. Can anyone tell me what they are? The only thing I can think of is perhaps it is a heavier object and it takes more time to instantiate so if you aren't changing the string too much, this would override the benefits of StringBuilder

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  • 'Caching' a large table in ASP.NET

    - by TheNewGuy
    I understand that each page refresh, especially in 'AjaxLand', causes my back-end/code-behind class to be called from scratch... This is a problem because my class (which is a member object in System.Web.UI.Page) contains A LOT of data that it sources from a database. So now every page refresh in AjaxLand is causing me to making large backend DB calls, rather than just to reuse a class object from memory. Any fix for this? Is this where session variables come into play? Are session variables the only option I have to retain an object in memory that is linked to a single-user and a single-session instance?

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  • Programming terms - field, member, properties (C#)

    - by Petr
    Hi, I was trying to find meaning of this terms but especially due to language barrier I was not able to understand what they are used for. I assume that "field" is variable (object too?) in the class while "property" is just an object that returns specific value and cannot contain methods etc. By "member" I understand any object that is declared on the class level. But these are just my assumptions based on commented code samples where some careful programmers used "property region" etc. I would really appreciate if someone could explain it to me.

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  • How to link .lib library in linux

    - by giga
    I'm pretty new to c programming and want to port a windows c application to linux. My code uses a .lib file va_g729.lib - is it possible to use the same library in Linux and compile it with gcc? All my .c and .h files along with the one .lib files are in the same directory. What I'm doing now is executing this command in the directory: gcc *.c -lm and I get following errors: lbcodec2.c:(.text+0xa6b): undefined reference to `va_g729a_init_encoder' lbcodec2.c:(.text+0xa83): undefined reference to `va_g729a_encoder' collect2: error: ld returned 1 exit status Is it possible to link the .lib file and compile with gcc? Thanks.

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  • Global Import/using Aliasing in .NET

    - by Josh Stodola
    Using import aliasing in a single class, we can reference class library namespaces by assigning our own custom alias like this: ' VB Imports Db = Company.Lib.Data.Objects // C# using Db = Company.Lib.Data.Objects; And then we are able to reference the classes inside of Company.Lib.Data.Objects by using the Db alias that we assigned. Is it possible to do this at the global level so that the alias is applied to the entire solution instead of the given file? Currently, we are working with web applications, so I was hoping we could add something to web.config, but I am also interested in whether or not this is possible with windows forms, console apps, and/or class libraries.

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  • Check constraint on table lookup

    - by bzamfir
    Hi, I have a table, department , with several bit fields to indicate department types One is Warehouse (when true, indicate the department is warehouse) And I have another table, ManagersForWarehouses with following structure: ID autoinc WarehouseID int (foreign key reference DepartmentID from departments) ManagerID int (foreign key reference EmployeeID from employees) StartDate EndDate To set new manager for warehouse, I insert in this table with EndDate null, and I have a trigger that sets EndDate for previous record for that warehouse = StartDate for new manager, so a single manager appears for a warehouse at a certain time. I want to add two check constraints as follows, but not sure how to do this do not allow to insert into ManagersForWarehouses if WarehouseID is not marked as warehouse Do not allow to uncheck Warehouse if there are records in ManagersForWarehouses Thanks

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  • ASP.NET - How can I cache user details for the duration of their visit?

    - by rockinthesixstring
    I've built a Repository that gets user details Public Function GetUserByOpenID(ByVal openid As String) As User Implements IUserRepository.GetUserByOpenID Dim user = (From u In dc.Users Where u.OpenID = openid Select u).FirstOrDefault Return user End Function And I'd like to be able to pull those details down IF the user is logged in AND IF the cached data is null. What is the best way to create a User object that contains all of the users details, and persist it across the entire site for the duration of their visit? I Was trying this in my Global.asax, but I'm not really happy using Session variables. I'd rather have a single object with all the details inside. Private Sub BaseGlobal_AcquireRequestState(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.AcquireRequestState If Session("UserName") Is Nothing AndAlso User.Identity.IsAuthenticated Then Dim repo As UrbanNow.Core.IUserRepository = New UrbanNow.Core.UserRepository Dim _user As New UrbanNow.Core.User _user = repo.GetUserByOpenID(User.Identity.Name) Session("UserName") = _user.UserName() Session("UserID") = _user.ID End If End Sub

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  • How do you make the script wait for the status of an Ajax get request before continuing?

    - by codeninja
    Basically what I'm doing is checking for the existence of an object, if it's not found, the script will try to load the source file using getScript. I only want to check this once though then return true or false to the function that calls fetch() fetch:function(obj){ ... isReady = false; $.getScript(obj.srcFile,function(){ isReady=true; warn("was able to load object "+key); }); return isReady; } but return kicks in before the script loads =/ later the script is loaded but the function returned false. This is the beauty of asynchronous I suppose... What's the best way to handle this... Maybe I could check again at some other point if the object exists? Or maybe there's a better way to do this where I dont have to potentially lock the browser?

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  • Should I convert data arrays to objects in PHP in a CouchDB/Ajax app?

    - by karlthorwald
    I find myself converting between array and object all the time in PHP application that uses couchDB and Ajax. Of course I am also converting objects to JSON and back (for sometimes couchdb but mostly Ajax), but this is not so much disturbing my workflow. At the present I have php objects that are returned by the CouchDB modules I use and on the other hand I have the old habbit to return arrays like array("error"="not found","data"=$dataObj) from my functions. This leads to a mixed occurence of real php objects and nested arrays and I cast with (object) or (array) if necessary. The worst thing is that I know more or less by heart what a function returns, but not what type (array or object), so I often run into type errors. My plan is now to always cast arrays to objects before returning from a function. Of course this implies a lot of refactoring. Is this the right way to go? What about the conversion overhead? Other ideas or tips?

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  • linq2sql left join with "multiselect"

    - by just_azho
    Hi, folks I'm trying to achieve following by linq2sql, but not successful. I've Member and Reference tables. DB is design in such a manner that Member can have multiple (=0) References. What I want as a result of query is, list (rows) of members, where all references of the member are "collected" in one column. What I had achieved is following query, but for this one there exist a row for each Reference. var refs = (from m in db.Members join r in db.References on m.PID equals r.PID into g from o in g.DefaultIfEmpty() select new { member = m, name = (o == null ? "" : o.NameSurname) }); I feel I need to insert SelectMany somewher :) Could you please give hints on achieving the goal?

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  • Initializing a value through a Session variable

    - by William Calleja
    I need to Initialize a value in a Javascript by using a c# literal that makes reference to a Session Variable. I am using the following code <script type="text/javascript" language="javascript" > var myIndex = <%= !((Session["myIndex"]).Equals(null)||(Session["myIndex"]).Equals("")) ? Session["backgroundIndex"] : "1" %>; However the code above is giving me a classic Object reference not set to an instance of an object. error. Why? Shouldn't (Session["myIndex"]).Equals(null) capture this particular error?

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  • Common type for generic classes of different types

    - by DinGODzilla
    I have (for example) Dictionary of different generic types (d1, d2, d3, d4) and I want to store them in something var d1 = new Dictionary<int, string>(); var d2 = new Dictionary<int, long>(); var d3 = new Dictionary<DateTime, bool>(); var d4 = new Dictionary<string, object>(); var something = ??? //new List<object> {d1, d2, d3, d4}; Is there any other way how to store that in something with common denominator different than object? Thanks :-)

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  • Updating the collections of entities with NHibernate the correct way

    - by karel_evzen
    A simple question regarding how NHibernate works: I have a parent entity that has a collection of other child entities. Those child entities have a reference to the parent entity they belong to. Now I want to implement an Add method to the parent entity that would add a child to it. Should that Add method only add the child to its new parents collection, or should it also update the parent reference of the child or should it also remove the added entity from its previous parents collection? Do I have to do all these things in that method or will NHibernate do something for me? Thanks.

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  • Hibernate + Spring + session + cache

    - by andromeda
    We are using Hibernate with Spring for our Java application. We find out that when a session update something in database other sessions can not see the update. For example user1 get the account balance from database then user2 increase the balance , if user1 get the object another time he see the account balance before updating (seems that session use the value from its cache) but we want to get the updated object with new account balance. User1 use one session during all activity that is different from user2 session. Is any configuration to force to get the updated object from database? or any other help?

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  • Carousel stopped working

    - by DenMed
    I can't get why, but suddenly my Bootstrap Carousel stopped working. I want it starts onload. Error from Chrome Console: Uncaught TypeError: Object [object Object] has no method 'carousel' :3000/assets/application.js?body=1:18 (anonymous function) :3000/assets/application.js?body=1:18 jQuery.Callbacks.fire jquery-1.7.2.js:1076 jQuery.Callbacks.self.fireWith jquery-1.7.2.js:1194 jQuery.extend.ready jquery-1.7.2.js:436 DOMContentLoaded jquery-1.7.2.js:950 In my application.js: $('.carousel').carousel({ interval: 2000 }) In my layout: <%= javascript_include_tag 'jquery-1.7.2', 'jquery.validate.min','application' %> Where is problem ?

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  • XPath to find an element with a similar sibling

    - by user364902
    Suppose I have this XML: <x> <e a='1' b='A'/> <e a='1' b='B'/> <e a='1' b='A'/> </x> I'd like to write an xpath to find any elements e which: Have attribute @b = 'A' Have the same value for attribute @a The xpath can't reference the literal value of attribute @a, however. It can reference the literal value of attribute @b. Or more generally, I want to find if there are any instances where there are two or more elements e[@b=A'] with the same value for attribute @a. Is this possible?

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  • PHP fb error posting story to user wall

    - by user237925
    I got an error from last 6 hrs. and stuck on it.While running my code i got this error again and again "Request failed with code: 400, message: {"error":{"message":"(#100) Object Invalid Value: Object at URL 'http://stayingnear.com/index.php?r=apartment\u00252Fview&id=1' of type 'stayingnearapp:apartment' is invalid because the given value '7.2853779052137E+14' for property 'fb:app_id' could not be parsed as type 'fbid'.","type":"OAuthException","code":100}}" is it the access token problem or what,and how can i handle this problem ?

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  • Flex: Problem with CollectionEvent on ArrayCollection

    - by dasnervtdoch
    Hi there, got a reference to an arrayCollection and add event listener like this: collection.addEventListener(CollectionEvent.COLLECTION_CHANGE, onCollectionChange); that´s fine. Now some other component does have the same reference and is adding items to and removing items from that collection. Each time the handler is called: private function onProjectPersonsChange(event:Event):void { if (event.kind == CollectionEventKind.ADD) { //do something } else if (event.kind == CollectionEventKind.REMOVE) { //do something //here is the problem: event.items.length = 0 } else { trace('CollectionEvent: kind not handled!'); } } Does somebody know why the removed item is not in 'items'? Thanks in advance!

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  • Singleton wrapper for Context

    - by kpdvx
    I'm considering creating a singleton wrapper for a Context so my model objects, if necessary, can open and read from a database connection. My model objects do not have access to a Context, and I'd like to avoid needing to pass a reference to a Context from object to object. I was planning to place into this singleton a reference to the Context returned by Application.getApplicationContext(). This singleton object would be initialized in my custom Application instance before anything else would need to or have a chance to use it. Can anyone think of a reason to not do this?

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  • scala coalesces multiple function call parameters into a Tuple -- can this be disabled?

    - by landon9720
    This is a troublesome violation of type safety in my project, so I'm looking for a way to disable it. It seems that if a function takes an AnyRef (or a java.lang.Object), you can call the function with any combination of parameters, and Scala will coalesce the parameters into a Tuple object and invoke the function. In my case the function isn't expecting a Tuple, and fails at runtime. I would expect this situation to be caught at compile time. object WhyTuple { def main(args: Array[String]): Unit = { fooIt("foo", "bar") } def fooIt(o: AnyRef) { println(o.toString) } } Output: (foo,bar)

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  • Accessing primitive properties from objects stored in a NSDictionary

    - by ChrisS
    Apologies if this is a basic question, I am just starting with Objective-C and trying to wrap things around in my head! I have a simple class of the form: @interface Whatever : NSObject { int somePrimitive; SomeObject* someObject; } @property (nonatomic) int somePrimitive; @property (nonatomic, retain) SomeObject* someObject; The class is more involved that this, but this illustrates the purpose. When I store instances of this class in a NSMutableDictionary: Whatever *whatever = [[Whatever alloc] init]; whatever.somePrimitive = 1; whatever.someObject = ...; [myDictionary setObject:whatever forKey:@"someKey"]; and then try to retrieve the object later: Whatever *result = [myDictionary valueForKey:@"someKey"]; then, result.someObject is ok to reference but, result.somePrimitive crashes. Does the NSDictionary not copy over the primitives of the object? Is the rule that the object stored in a dictionary should only contain objects?

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