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  • Maintaining sort order of database table rows

    - by Lox
    Say I have at database table containing information about a news article in each row. The table has an integer "sort" column to dictate the order in which the articles are to be presented on a web site. How do I best implement and maintain this sort order. The problem I want to avoid is having the the articles numbered 1,2,3,4,..,100 and when article number 50 suddenly becomes interesting it gets its sort number set to 1 and then all articles between them must have their sort number increased by one. Sure, setting initial sort numbers to 100,200,300,400 etc. leaves some space for moving around but at some point it will break. Is there a correct way to do this, maybe a completely different approach? Added-1: All article titles are shown in a list linking to the contents, so yes all sorted items are show at once. Added-2: An item is not necessarily moved to the top of the list; any item can be placed anywhere in the ordered list.

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  • Visitor Pattern can be replaced with Callback functions?

    - by getit
    Is there any significant benefit to using either technique? In case there are variations, the Visitor Pattern I mean is this: http://en.wikipedia.org/wiki/Visitor_pattern And below is an example of using a delegate to achieve the same effect (at least I think it is the same) Say there is a collection of nested elements: Schools contain Departments which contain Students Instead of using the Visitor pattern to perform something on each collection item, why not use a simple callback (Action delegate in C#) Say something like this class Department { List Students; } class School { List Departments; VisitStudents(Action<Student> actionDelegate) { foreach(var dep in this.Departments) { foreach(var stu in dep.Students) { actionDelegate(stu); } } } } School A = new School(); ...//populate collections A.Visit((student)=> { ...Do Something with student... }); *EDIT Example with delegate accepting multiple params Say I wanted to pass both the student and department, I could modify the Action definition like so: Action class School { List Departments; VisitStudents(Action<Student, Department> actionDelegate, Action<Department> d2) { foreach(var dep in this.Departments) { d2(dep); //This performs a different process. //Using Visitor pattern would avoid having to keep adding new delegates. //This looks like the main benefit so far foreach(var stu in dep.Students) { actionDelegate(stu, dep); } } } }

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  • Why does C++ mandate that complex only be instantiated for float, double, or long double?

    - by templatetypedef
    According to the C++ ISO spec, §26.2/2: The effect of instantiating the template complex for any type other than float, double or long double is unspecified. Why would the standard authors explicitly add this restriction? This makes it unspecified, for example, what happens if you make complex<int> or a complex<MyCustomFixedPointType> and seems like an artificial restriction. Is there a reason for this limitation? Is there a workaround if you want to instantiate complex with your own custom type? I'm primarily asking this question because of this earlier question, in which the OP was confused as to why abs was giving bizarre outputs for complex<int>. That said, this still doesn't quite make sense given that we also might want to make complex numbers out of fixed-points types, higher-precision real numbers, etc. Thanks!

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  • Android 2.1 address bar causes change in viewport dimensions

    - by davehumyo
    Hi, I have a page that has a 100% width and height div in it (all surrounding elements are sized accordingly so that it does actually achieve 100% width and height). Below that div I have a second div with a fixed height. In mobile safari and blackberry everything is fine, when the page loads the dimensions are applied correctly (the top div filling the viewport) and the user can scroll down to reveal the second div. Android 2.1 also applies the dimensions correctly, but with an added quirk; when the user scrolls down and removes the address bar from the page, the dimensions of the div are recalculated to fill the viewport, causing the content to jump. Ideally I would like the dimensions of the div to remain static when the page is scrolled, but remain 100% so that it will fill the viewport regardless of device size or orientation. Does anyone know of any way to disable this recalculation? Thanks for any help you can provide.

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  • How to use a 3rd party control inside the viewmodel?

    - by Sander
    I have a 3rd party control which among other things performs loading of some data. I want my viewmodel to keep track of this load operation and adjust its own state accordingly. If it were up to me, I'd do the data loading far away from the view, but it is not. So, I seem to be in the situation where my viewmodel depends on my view. How do I best handle this? I feel rather dirty making the view publish events to the viewmodel but I don't see any other reasonable way to get this info into the viewmodel. A similar situation might crop up with standard controls, too - imagine if your viewmodel depends on the events coming from a MediaElement - how do you properly model this? Do you put the MediaElement into the viewmodel? That doesn't sound right. If publishing the events to the viewmodel is indeed the most reasonable way, is there some common pattern used for this? How do you do it?

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  • How to export data which are mapped to enumerations

    - by Joshua
    I have a set of data which needs to be imported from a excel sheet, lets take the simplest example. Note: the data might eventually support uploading any locale. e.g. assuming one of the fields denoting a user is gender mapped to an enumeration and stored in the database as 0 for male and 1 for female. 0 and 1 being short values. If I have to import the values I cannot expect the user to punch in numbers (since they are not intuitive and is cumbersome when the enumerations are bigger), what would be the correct way to map to enumerations. Should we ask them to provide a string value in these cases (e.g. male or female) and provide the transformation to a enum in our code by wring a method public static Gender Gender.fromString(String value)

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  • How to hire a good ui designer

    - by Mark
    I have a webapp that can probably look better. Looking on jobs.stackoverflow, all I see for UI jobs are full-time positions. Is it possible to hire a good UI designer for freelance work? Where would I begin? And anyone know how much I would be looking at?

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  • How to use Unique Composite Key

    - by LifeH2O
    I have a table Item(ItemName*, ItemSize*, Price, Notes) I was making composite key of (ItemName,ItemSize) to uniquely identify item. And now after reading some answers on stackoverflow suggesting the use of UNIQUE i revised it as Item(ItemID*, ItemName, ItemSize, Price, Notes) But How to apply UNIQUE constraint on ItemName and ItemSize please correct if there is something wrong in question

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  • which is better, creating a materialized view or a new table?

    - by Carson
    I have some demanding mysql queries that are needed to grap same up-to-date datasets from 5-7 mysql tables. I am thinking of creating a table or materialized view to gather all demanding columns from other tables, so as to increase performance. If I create that table, I may need to do extra insert / update / delete operation each time other tables updated. if I create materialized view, I am worrying if the performance can be greatly improved. Because data from other tables are changing very frequently. Most likely, the view may need to be created first everytime before selecting it. Any ideas? e.g. how to cache? other extra measures I can do?

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  • Configuration and Model-View

    - by HH
    I am using the Model-View pattern on a small application I'm writing. Here's the scenario: The model maintains a list of directories from where it can extract the data that it needs. The View has a Configuration or a Setting dialog where the user can modify this list of directories (the dialog has a JList displaying the list in addition to add and remove buttons). I need some advice from the community: The View needs to communicate these changes to the model. I thought first of adding to the model these methods: addDirectory() and removeDirectory(). But I am trying to limit the number of methods (or channels) that the View can use to communicate with and manipulate the model. Is there any good practice for this? Thank you.

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  • Should Factories Persist Entities?

    - by mxmissile
    Should factories persist entities they build? Or is that the job of the caller? Pseudo Example Incoming: public class OrderFactory { public Order Build() { var order = new Order(); .... return order; } } public class OrderController : Controller { public OrderController(IRepository repository) { this.repository = repository; } public ActionResult MyAction() { var order = factory.Build(); repository.Insert(order); ... } } or public class OrderFactory { public OrderFactory(IRepository repository) { this.repository = repository; } public Order Build() { var order = new Order(); ... repository.Insert(order); return order; } } public class OrderController : Controller { public ActionResult MyAction() { var order = factory.Build(); ... } } Is there a recommended practice here?

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  • Are today's young programmers getting wrapped around the axle with patterns and practices?

    - by Robert Harvey
    Recently I have noticed a number of questions on SO that look something like this: I am writing a small program to keep a list of the songs that I keep on my ipod. I'm thinking about writing it as a 3-tier MVC Ruby on Rails web application with TDD, DDD and IOC, using a factory pattern to create the classes and a singleton to store my application settings. Do you think I'm taking the right approach? Do you think that we're handing novice programmers a very sharp knife and telling them, "Don't cut yourself with this"? NOTE: Despite the humorous tone, this is a serious (and programming-related) question.

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  • Alternatives to checking against the system time

    - by vikp
    Hi, I have an application which license should expire after some period of time. I can check the time in the applicatino against the system time, but system time can be changed by the administrator, therefore it's not a good idea to check against the system time in my opinion. What alternatives do I have? Thank you

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  • Why does C# allow abstract class with no abstract members?

    - by fatcat1111
    The C# spec, section 10.1.1.1, states: An abstract class is permitted (but not required) to contain abstract members. This allows me to create classes like this: public abstract class A { public void Main() { // it's full of logic! } } This is really a concrete class; it's only abstract in so far as one can't instantiate it. If inheritors don't actually have to provide implementation, then why call it abstract?

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  • Photoshop and Saving Quality

    - by ITg
    I'm making a simple image for the web which is a gradient with some text on in Photoshop CS4. The text doesn't seem to be of a great quality. If you look at the logo of stackoverflow you can see that its pretty accurate. Mine don't seem to render properly round the edges. Anyone know how to get the best quality? Photoshop CS4. Thanks.

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  • anti-if campaign

    - by Andrew Siemer
    I recently ran against a very interesting site that expresses a very interesting idea - the anti-if campaign. You can see this here at www.antiifcampaign.com. I have to agree that complex nested IF statements are an absolute pain in the rear. I am currently on a project that up until very recently had some crazy nested IFs that scrolled to the right for quite a ways. We cured our issues in two ways - we used Windows Workflow Foundation to address routing (or workflow) concerns. And we are in the process of implementing all of our business rules utilizing ILOG Rules for .NET (recently purchased by IBM!!). This for the most part has cured our nested IF pains...but I find myself wondering how many people cure their pains in the manner that the good folks at the AntiIfCampaign suggest (see an example here) by creating numerous amounts of abstract classes to represent a given scenario that was originally covered by the nested IF. I wonder if another way to address the removal of this complexity might also be in using an IoC container such as StructureMap to move in and out of different bits of functionality. Either way... Question: Given a scenario where I have a nested complex IF or SWITCH statement that is used to evaluate a given type of thing (say evaluating an Enum) to determine how I want to handle the processing of that thing by enum type - what are some ways to do the same form of processing without using the IF or SWITCH hierarchical structure? public enum WidgetTypes { Type1, Type2, Type3, Type4 } ... WidgetTypes _myType = WidgetTypes.Type1; ... switch(_myType) { case WidgetTypes.Type1: //do something break; case WidgetTypes.Type2: //do something break; //etc... }

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  • jQuery's draggable grid

    - by Art
    It looks like that the 'grid' option in the constructor of Draggable is relatively bound to the original coordinates of the element being dragged - so simply put, if you have three draggable divs with their top set respectively to 100, 200, 254 pixels relative to their parent: <div class="parent-div" style="position: relative;"> <div id="div1" class="draggable" style="top: 100px; position: absolute;"></div> <div id="div2" class="draggable" style="top: 200px; position: absolute;"></div> <div id="div3" class="draggable" style="top: 254px; position: absolute;"></div> </div> Adn all of them are getting enabled for dragging with 'grid' set to [1, 100]: draggables = $('.draggable'); $.each(draggables, function(index, elem) { $(elem).draggable({ containment: $('#parent-div'), opacity: 0.7, revert: 'invalid', revertDuration: 300, grid: [1, 100], refreshPositions: true }); }); Problem here is that as soon as you drag div3, say, down, it's top is increased by 100, moving it to 354px instead of being increased by just mere 46px (254 + 46 = 300), which would get it to the next stop in the grid - 300px, if we are looking at the parent-div as a point of reference and "grid holder". I had a look at the draggable sources and it seem to be an in-built flaw - they just do all the calculations relative to the original position of the draggable element. I would like to avoid monkey-patching the code of draggable library and what I am really looking for here is the way how to make the Draggable calculate the grid positions relative to containing parent. However if monkey-patching is unavoidable, I guess I'll have to live with it. Thanks!

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  • Feature categories for a social network

    - by mafutrct
    Not sure if this question belongs on SO. Anyway, please let me try to clarify the issue. I'm currently planning a social program. It's basically a chat server with the major additional ability to play games. I'd like to create categories of features that are offered to users. My question is, are there any useful standard feature categories? Does not have to be specific to my case, I'm interested in the general case as well. Just to give you an idea of what I'm thinking: functional e.g. play games social e.g. chatting operational e.g. 24/7 service availability I'm entirely unsure if this is the right place to ask, if you know of any better site to ask please don't hesitate to add a comment.

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  • Which fieldtype is best for storing PRICE values?

    - by BerggreenDK
    Hi there I am wondering whats the best "price field" in MSSQL for a shoplike structure? Looking at this overview: http://www.teratrax.com/sql_guide/data_types/sql_server_data_types.html We have datatypes called money, smallmoney, then we have decimal/numeric and lastly float and real Name, memory/disk-usage and value ranges: Money: 8 bytes (values: -922,337,203,685,477.5808 to +922,337,203,685,477.5807) Smallmoney: 4 bytes (values: -214,748.3648 to +214,748.3647) Decimal: 9 [default, min. 5] bytes (values: -10^38 +1 to 10^38 -1 ) Float: 8 bytes (values: -1.79E+308 to 1.79E+308 ) Real: 4 bytes (values: -3.40E+38 to 3.40E+38 ) My question is: is it really wise to store pricevalues in those types? what about eg. INT? Int: 4 bytes (values: -2,147,483,648 to 2,147,483,647) Lets say a shop uses dollars, they have cents, but I dont see prices being $49.2142342 so the use of a lot of decimals showing cents seems waste of SQL bandwidth. Secondly, most shops wouldn't show any prices near 200.000.000 (not in normal webshops at least... unless someone is trying to sell me a famous tower in Paris) So why not go for an int? An int is fast, its only 4 bytes and you can easily make decimals, by saving values in cents instead of dollars and then divide when you present the values. The other approach would be to use smallmoney which is 4 bytes too, but this will require the math part of the CPU to do the calc, where as Int is integer power... on the downside you will need to divide every single outcome. Are there any "currency" related problems with regionalsettings when using smallmoney/money fields? what will these transfer too in C#/.NET ? Any pros/cons? Go for integer prices or smallmoney or some other? Whats does your experience tell?

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  • Best practice to modularise a large Grails app?

    - by Mulone
    Hi all, A Grails app I'm working on is becoming pretty big, and it would be good to refactor it into several modules, so that we don't have to redeploy the whole thing every time. In your opinion, what is the best practice to split a Grails app in several modules? In particular I'd like to create a package of domain classes + relevant services and use it in the app as a module. Is this possible? Is it possible to do it with plugins? Cheers, Mulone

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  • top-k selection/merge

    - by tcurdt
    I have n sorted lists. These lists are quite long (300000+ tuples). Selecting the top 10 of the individual lists is of course trivial - they are right at the head of the lists. Where it gets more interesting is when I want the top 10 of all the sorted lists. The question is whether there is an algorithm to calculate the combined top 10 having the correct order while cutting off the long tail of the lists. The goal is to reduce the required space. And if there is: How does one find the limit where is is safe to cut? Note: The actual counts are not important. Only the order is.

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  • Javascript libraries + JQuery plugins contradict? How to debug?

    - by Metafaniel
    This is somewhat a newbie question... I effort everyday to learn, so please understand ;) I'm not the very best expert, but I can do a decent job good looking and functional websites or web applications. My main tools are PHP5, HTML5, CSS2 y 3, a database (SQLite, MySQL) and Javascript and JQuery. I'm not an expert at all in Javascript. I often find interesting JQuery plugins or tutorials and try to mix them up to do the functionality needed. This time I'm mixing maybe too much plugins and js files from different sources. In fact, my app do what I want except for certain behaviors... There are no errors, everything looks fine, but the misbehavior persists. So maybe I need to specify a class I don't know about, or one contradicts another one from another plugin and I just can't understand, for example, why a <button type="button">DON'T submit</button> just submits the form... Anyway, my point is: Do you people know a way to debug this situations??? Is there a generic tool, suggestion, workflow or something to help me understand conflicts or omissions between libraries or plugins??? (Javascript libraries, my own Javascripts and JQuery plugins)??? I hope it is a way! THANKS A LOT FOR YOUR HELP AND COMPREHENSION! =)

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  • Strange CSS Positioning issue with a fader on a responsive site

    - by EPICWebDesign
    I'm developing a prototype responsive wordpress theme version of my homepage. I'm running into issues with the fader on the homepage. http://dev.epicwebdesign.ca/epicblog/ When the image switches, it uses position:absolute to overlay the pictures, then goes back to position:relative. I need to make the absolute be relative to the bottom left corner of the menu instead of the top left corner of #wrap so it doesn't overlap. I tried putting it in a container div like this: http://wiki.orbeon.com/forms/doc/contributor-guide/browser#TOC-Absolutely-positioned-box-inside-a-box-with-overflow:-auto-or-hidden but that doesn't seem to work. Any ideas? There are major CSS compatibility issues in IE, try it in chrome. It should look similar to http://epicwebdesign.ca. When the browser window is shrunk horizontially, the whole theme compensates.

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  • What's the proper way of importing option lists into an Android app?

    - by Scott
    I have been storing option lists for my Android app in a cloud table. For example, categories like "historical fiction","biography","science fiction", etc. I see the following pros and cons: Pro: I can make changes to the list without sending an app update to Google Play Not normalized - I can use the text in my other data tables instead of a reference ID Con: App needs to take time to download from the web each time (or at least check for changes) English only I believe the "proper" way to do this is the use the XML resource files. But I need to make sure the selection references correctly with my data. That is, my app needs to understand that "Poetry" and "Poesía" are the same thing. Is the correct thing to do: Forget about it since I'll never get to the point where I'm translating my app anyway Use a string-array and use the index (0...x) to know what the selection is Use a 2-dimensional string-array with a reference ID in the first column and the text in the second?

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