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• What are the benefits and risks of moving to a Model Driven Architecture approach?

  - by Tone

  I work for a company with about 350 employees and we are in the process of growing. Our current codebase is not structured very well and we are looking both at how to improve it immediately (by organizing objects into namespaces, separating concerns, etc.) and moving to a model driven architecture approach, where we model and design everything first with uml, then generate code from that model. We have been looking heavily at Sparx Systems Enterprise Architect (EA) (which is UML 2.0 capable) and we are also considering the tools in VS 2010. I know there are other tools out there (Rational XDE being one) but I really do not think we can spend $1500+ per license at this point. I'm not looking for answers on which tool is better than another but more for experiences moving from a cowboy coding environment (that is, little planning and design, just jump in and start coding) to a model driven architecture. Looking back was it helpful to your organization? What are the pain points? What are the risks? What are the benefits?

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• Dynamic GUI Framework Designing

  - by user575715

  There is a Scenario to be developed for a 3-tier Application .We need to design a Framework or a utility sort of thing . In tradional aspect of GUI Designing , either we tend to create a static gui page and code the elements on it along with other properties of the elements such as (disabled/enabled,image source,name ,id ,which function to be called under onclick event.) or we tend to drag and drop the elements from the control pallete provided by variety of gui frameworks. Certain things i need to design a POC so that we can develop this concept. 1) There must a utility ,such that during creation of screen layout , that screen should be saved in the database(RDBMS) with a screen number. 2) All the Events related to that control should be saved in some other table which will be dynamically mapped during the calling of screen number by the user. 3) When the user call that screen ,a generic function should be invoked which'll call the screen file from the database and apply all the properties ,events,etc at runtime and the final output will be displayed to the user. This POC will help the us to customised the screens according to our usage.also all the code will seperated which can easily be used for some other development process. Thanks Amit Kalra

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• How do you use indent in vim for web development?

  - by Somebody still uses you MS-DOS

  I'm starting to use Linux and Vim at work. I'm starting to read vims documentation and creating my own .vimrc file and such. I'm a web developer working with HTML, XML, CSS, JS, Python, PHP, ZPT, DTML and SQL. I would like to have an indent feature like this one: for each language/set, a corresponding indent solution. So, in js, writing function test(){|} would turn in function test(){ | } If php, writing <?php function test(){|}: <?php function test(){ | } <?php> ...and such. Writing a function definition in Python, and then creating a for loop sentece, it would automatically create an indent. I'm starting with autoindent, smartindent, cindent but I'm a little confused about their differences. How do the indent in vim works? Am I supposed to download plugins for each language? Is the behavior I described possible with already existing plugins you're used to or do I have to create it? I keep seeing people using Vim and I'm trying to do this as well since the machine I'm using is too limited, but I'm afraid I won't be able to have a decent auto indenting solution in it. (I have used autoindenting in a little small project in Visual Studio, and really liked their approach. Is there a plugin for that?)

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• How Best to Replace PL/SQL with C#?

  - by Mike

  Hi, I write a lot of one-off Oracle SQL queries/reports (in Toad), and sometimes they can get complex, involving lots of unions, joins, and subqueries, and/or requiring dynamic SQL, and/or procedural logic. PL/SQL is custom made for handling these situations, but as a language it does not compare to C#, and even if it did, it's tooling does not, and if even that did, forcing yet another language on the team is something to be avoided whenever possible. Experience has shown me that using SQL for the set based processing, coupled with C# for the procedural processing, is a powerful combination indeed, and far more readable, maintainable and enhanceable than PL/SQL. So, we end up with a number of small C# programs which typically would construct a SQL query string piece by piece and/or run several queries and process them as needed. This kind of code could easily be a disaster, but a good developer can make this work out quite well, and end up with very readable code. So, I don't think it's a bad way to code for smaller DB focused projects. My main question is, how best to create and package all these little C# programs that run ad hoc queries and reports against the database? Right now I create little report objects in a DLL, developed and tested with NUnit, but then I continue to use NUnit as the GUI to select and run them. NUnit just happens to provide a nice GUI for this kind of thing, even after testing has been completed. I'm also interested in suggestions for reporting apps generally. I feel like there is a missing piece or product. The perfect tool would allow writing and running C# inside of Toad, or SQL inside of Visual Studio, along with simple reporting facilities. All ideas will be appreciated, but let's make the assumption that PL/SQL is not the solution.

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• Java, Massive message processing with queue manager (trading)

  - by Ronny

  Hello, I would like to design a simple application (without j2ee and jms) that can process massive amount of messages (like in trading systems) I have created a service that can receive messages and place them in a queue to so that the system won't stuck when overloaded. Then I created a service (QueueService) that wraps the queue and has a pop method that pops out a message from the queue and if there is no messages returns null, this method is marked as "synchronized" for the next step. I have created a class that knows how process the message (MessageHandler) and another class that can "listen" for messages in a new thread (MessageListener). The thread has a "while(true)" and all the time tries to pop a message. If a message was returned, the thread calls the MessageHandler class and when it's done, he will ask for another message. Now, I have configured the application to open 10 MessageListener to allow multi message processing. I have now 10 threads that all time are in a loop. Is that a good design?? Can anyone reference me to some books or sites how to handle such scenario?? Thanks, Ronny

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• How can I manage a FIFO-queue in an database with SQL?

  - by Jonas

  I have two tables in my database, one for In and one for Out. They have two columns, Quantity and Price. How can I write a SQL-query that selects the correct price? In example: If I have 3 items in for 75 and then 3 items in for 80. Then I have two out for 75, and the third out should be for 75 (X) and the fourth out should be for 80 (Y). How can I write the price query for X and Y? They should use the price from the third and forth row. In example, is there any way to SELECT the third row in the In-table? I can not use auto_increment as identifier for i.e. "third" row, because the tables will contain post for other items too. The rows will not be deleted, they will be saved for accountability reasons. SELECT Price FROM In WHERE ...? NEW database design: +----+ | In | +----+------+-------+ | Supply_ID | Price | +-----------+-------+ | 1 | 75 | | 1 | 75 | | 1 | 75 | | 2 | 80 | | 2 | 80 | +-----------+-------+ +-----+ | Out | +-----+-------+-------+ | Delivery_ID | Price | +-------------+-------+ | 1 | 75 | | 1 | 75 | | 2 | X | <- ? | 3 | Y | <- ? +-------------+-------+ OLD database design: +----+ | In | +----+------+----------+-------+ | Supply_ID | Quantity | Price | +-----------+----------+-------+ | 1 | 3 | 75 | | 2 | 3 | 80 | +-----------+----------+-------+ +-----+ | Out | +-----+-------+----------+-------+ | Delivery_ID | Quantity | Price | +-------------+----------+-------+ | 1 | 2 | 75 | | 2 | 1 | X | <- ? | 3 | 1 | Y | <- ? +-------------+----------+-------+

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• Problem with function calls [javascript]

  - by Samuel

  <script language="javascript"> function toggle(id) { alert('call'); if (document.getElementById(id).style.display == "none") { alert('now visible'); document.getElementById(id).style.display = ""; } else { alert('now invisible'); document.getElementById(id).style.display = "none"; } } </script> </head> <body onload="toggle('image1');alert('test_body');toggle('image2')"> <script language="javascript"> alert('test_pre_function'); toggle('image1'); alert('test_after_function'); toggle('image2'); </script> Looks like a lot of code but it's pretty simple so i think most of you won't have troubles with it. toggle() should toggle the display status of divs containing images. When the user enters the site the divs should hide, when everything is loaded the divs should show up. (onload) Strangely enough, the funtion in the body (not in the body tag) only work half, i get and alert 'test_pre_function' and i get an alert 'call' (out of the function), but that's it. The code in the body tag runs just fine. I find this weird because it's supposed to do exactly the same twice and one time it runs, another time not, so i guess i must have made some stupid mistake. Thanks for any help!

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• Should a programmer have mastery over C++

  - by Yogendra

  I was wondering if it is necessary for programmers to have expertise on at least 1 programming language? Programming languages like C#, java, VB.Net etc change every year or two. Should a programmer have mastery over C++, which is a stable language and rarely undergoes changes? I am a C# developer and using it for about 7 years now, I still don't have mastery on it. EDIT I think my question is being misunderstood. I am not against changes or evolution. I love the new features and abstraction provided by languages such as C#, VB, Java. And I keep waiting for new features if it makes a programmers life easy. But this fact also make this languages very difficult to master. They are continuously evolving. Languages like C++ have slow evolution cycle. So given this scenario, Is it helpful to be master of C++? This is what my original question meant. Note:- Based on the answers by friends below, I have understood that languages and framework are tools for expressing the concepts. Also it might be a good idea to express the concepts in different programming languages.

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• Generating jquery 'rules' from business model to UI in asp.net mvc

  - by jim

  Hi all, I've had a good look around and am certain that there's no matching question on SO, so here goes. Has anyone created a 'helper' method on their model that generates jquery (or plain javascript) rules validation dynamically, based on the criteria/rules that are contained within the object and taken from a repository (i.e. DB). What i'm thinking of is a discrete set of partial views (and associated models) that have rules at the business logic 'level' and rather than (or in combination with) validating the rule(s) at postback, translating the same rules into tightly focussed jquery methods that work identically at client (js) and server (c#) levels. I can see benefits here re performance. Also, the rules definitions could be created in a single place (in c#) and the jquery generated off of that, thus allowing single edits to update both code streams. I appreciate that there would be limitations imposed by language specific contstraints but the general principle could be quite interesting if used appropriately. I'm also aware that testibility could be an issue when using two different language structures and hoping to achieve similar test outcomes - but those aside... any thoughts or experiences of similar out there?? cheers jimi

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• Urgent Help not showing the grid on the page..

  - by kumar

  hello Friends, I have two user controlers 1) name.ascx 2) friends.ascx in both controlers Code is same just changing the Grid name and columns but URL pointing is differnt.. <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<JQGridMVCExamples.Models.OrdersJqGridModel>" %> <div> <%= Html.Trirand().JQGrid(Model.OrdersGrid, "JQGrid1") %> </div> <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<JQGridMVCExamples.Models.OrdersJqGridModel2>" %> <div> <%= Html.Trirand().JQGrid(Model.OrdersGrid2, "JQGrid2") %> </div> But what hapeening is for second gri JQGrid2 is not showing up.. but First Grid is showing.. when i do first time second grid execution is not shoiwng up but when I do after first grid.. I am getting the result but Frist grid columns I am getting not the second grid columns.. can any body have sujjestion on this? thanks

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• C# Type conversion between two similar Datatable objects

  - by Ali

  I have .NET project with sync framework and two separate Datasets for MS SQL and Compact SQL. in my base class I have a generic DataTable object. in my derived classed I assign Typed DataTable to the generic object based on whether the application is operating online or offline: example: if (online) _dataTable = new MSSQLDataSet.Customer; else _dataTable = new CompactSQLDataSet.Customer; Now every where in my code i have to check and do a cast based on the current network mode like this: public void changeCustomerID(int ID) { if (online) (MSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; else (CompactMSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; } but I don't think this is very efficient and I believe it can be done in a smarter way to only use one line of code by dynamically getting the Type of _dataTable on the run time. my problem is at the design time, in order to acess datatable porperties such as "CustomerID" it has to be casted to either MSSQLDataSet.CustomerDataTable or CompactMSSQLDataSet.CustomerDataTable. Is there a way to have a function or a operator to convert the _datatable to its runtime type but still be able to use it's design time properties which are the same between the two types? something like: ((aType)_dataTable)[i].CustomerID = value; //or GetRuntimeType(_dataTable)[i].CustomerID = value;

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• Launch app with specific locale

  - by hermo

  Changing the locale for a device is done in the settings, and can't be done by an app AFAIK. I know how to force my own app to a specific locale, described e.g. here: http://www.tutorialforandroid.com/2009/01/force-localize-application-on-android.html So now to my question. Can I force, programatically, the local of an activity that isn't mine? I can imagine 2 ways this could be possible: Specifying the locale in an Intent used to start the activity. Access and manipulate the configuration of running activities (in the same way as I can modify my own activities' configurations). Any thoughts? Is it possible? Is it reasonable? I guess 2. would be more direct, but require some kind of permission (e.g. the modified atcitiy must allow it in the manifest file). But I'd settle for 1. or similar. What I want is to be able to see certain apps in a different language, but rather not change the system locale. E.g. the Android Market, that only displays comments in one language. Can't think of other things right now. Can't find much written on Locale in the documentation, what is and isn't possible. But hoping some undocumented feature might enable this :)

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• Code Analysis Warning CA1004 with generic method

  - by Vaccano

  I have the following generic method: // Load an object from the disk public static T DeserializeObject<T>(String filename) where T : class { XmlSerializer xmlSerializer = new XmlSerializer(typeof(T)); try { TextReader textReader = new StreamReader(filename); var result = (T)xmlSerializer.Deserialize(textReader); textReader.Close(); return result; } catch (FileNotFoundException) { } return null; } When I compile I get the following warning: CA1004 : Microsoft.Design : Consider a design where 'MiscHelpers.DeserializeObject(string)' doesn't require explicit type parameter 'T' in any call to it. I have considered this and I don't know a way to do what it requests with out limiting the types that can be deserialized. I freely admit that I might be missing an easy way to fix this. But if I am not, then is my only recourse to suppress this warning? I have a clean project with no warnings or messages. I would like to keep it that way. I guess I am asking "why this is a warning?" At best this seems like it should be a message. And even that seems a bit much. Either it can or it can't be fixed. If it can't then you are just stuck with the warning with no recourse but suppressing it. Am I wrong?

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• Is this XML file correct for RSS feeding?

  - by Hermet

  Hi guys I am generating a XML-RSS type file from PHP. The output for example is like this <?xml version="1.0" encoding="iso-8859-1"?> <rss version="2.0"> <channel> <title>Mi web mola</title> <link>http://www.dominio.com/blog.php</link> <language>es-ES</language> <description>Mallas y eso</description> <generator>Autor</generator> <item> <title>Articulo de prueba</title> <link>http://www.midominio.com/2342</link> <pubDate>14/06/2010</pubDate> <description><![CDATA[Descripcion de prueba bla bla bla]]></description> <content:encoded><![CDATA[Contenido prueba]]></content:encoded> </item> </channel> </rss> ... and all I can see in the Firefox preview is the title and the description of the blog, not the items, but in the source it appears correctly, so I've thought it must be a parse error or something like that.. What could be wrong? Again, excuse me for my bad english, and thank you very much.

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• How does Crystal Reports Runtime Licensing work?

  - by GluedHands

  I am designing an application in C# and I want to use some Crystal Reports in my application. I am selling this application as freelance to a small business. This is my first program that I have ever sold. I have Crystal Reports 2008 that I am using to design reports with. Do I need to get any kind of licensing from Business Objects to include the Crystal Reports Runtime for report printing in my application? Or do I not need to worry about it as long as I have a licensed version of Crystal Reports 2008 on my development machine. The client would only need be able to print the reports that I have designed on my machine, not design their own. The reports would be saved as a file. The application will load the saved report and print it with provided data. I did see this article which answers the most part of my question. However, it does not include whether it covers loading saved report documents? Any additional related information for a commercial product newbie is gladly appreciated.

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• return Queryable<T> or List<T> in a Repository<T>

  - by Danny Chen

  Currently I'm building an windows application using sqlite. In the data base there is a table say User, and in my code there is a Repository<User> and a UserManager. I think it's a very common design. In the repository there is a List method: //Repository<User> class public List<User> List(where, orderby, topN parameters and etc) { //query and return } This brings a problem, if I want to do something complex in UserManager.cs: //UserManager.cs public List<User> ListUsersWithBankAccounts() { var userRep = new UserRepository(); var bankRep = new BankAccountRepository(); var result = //do something complex, say "I want the users live in NY //and have at least two bank accounts in the system } You can see, returning List<User> brings performance issue, becuase the query is executed earlier than expected. Now I need to change it to something like a IQueryable<T>: //Repository<User> class public TableQuery<User> List(where, orderby, topN parameters and etc) { //query and return } TableQuery<T> is part of the sqlite driver, which is almost equals to IQueryable<T> in EF, which provides a query and won't execute it immediately. But now the problem is: in UserManager.cs, it doesn't know what is a TableQuery<T>, I need to add new reference and import namespaces like using SQLite.Query in the business layer project. It really brings bad code feeling. Why should my business layer know the details of the database? why should the business layer know what's SQLite? What's the correct design then?

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• Self organizing layouts

  - by user613326

  Quite a while ago i was more in websites building then i am now. In my time there where huge debates about what to use; tables or pure CSS alternatives. I went out of the webdesigning, but now an old question re-surfaces. What i would like to create is a web page design that depending on screensize, would self organize the page into columns, so that for example on a PDA it would show 1 column On an old computer monitor, it would show 2 colomns, and on a widescreen laptop it would show 3 columns. I forgot how this was called and how it was done in the past, it had to do with XML and storing data seperate from design (if i remember well), perhaps these days better methods exist to do that, does this, anyone ring this a bell ? Also i note a lot is possible with Jquery and and brouwser depending webkits. But i need to make sure that it would run on all (modern) brouwsers : Iexplorer, Firefox, chrome And Jquery is nice too, but i am kinda woried that some day one of these brouwser vendors decides that jscript like java isnt enabled by default (or is that very unlikely ?)11 Perhaps someone can point me to a method that is the prefered way to do this.

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• TinyMCE loading lang/plugins/theme from incorrect directory

  - by Anonymous

  I am having trouble with TinyMCE. When it is searching for the lang, theme, and plugins, it is supposed to look in the directory where the base script files are located. however, instead of doing that, it is using the current loaded page as the root for searching. I am looking at the "loadScripts" function in the src file, but changing the path doesn't seem to provide any meaningful effect. Here is the unmodified loadScripts function for your review: // Load scripts function loadScripts() { if (s.language) sl.add(tinymce.baseURL + '/langs/' + s.language + '.js'); if (s.theme && s.theme.charAt(0) != '-' && !ThemeManager.urls[s.theme]) ThemeManager.load(s.theme, 'themes/' + s.theme + '/editor_template' + tinymce.suffix + '.js'); each(explode(s.plugins), function(p) { if (p && p.charAt(0) != '-' && !PluginManager.urls[p]) { // Skip safari plugin for other browsers if (!isWebKit && p == 'safari') return; PluginManager.load(p, 'plugins/' + p + '/editor_plugin' + tinymce.suffix + '.js'); } }); // Init when que is loaded sl.loadQueue(function() { if (!t.removed) t.init(); }); }; loadScripts(); }

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• What is better: Developing a Web project in MVC or N -Tier Architecture?

  - by Starx

  I have asked a similar question before and got an convincing answer as well? http://stackoverflow.com/questions/2843311/what-is-difference-of-developing-a-website-in-mvc-and-3-tier-or-n-tier-architectu Due to the conclusion of this question I started developing projects in N-tier Architecture. Just about an hour ago, I asked another question, about what is the best design pattern to create interface? There the most voted answer is suggesting me to use MVC architecture. http://stackoverflow.com/questions/2930300/what-is-the-best-desing-pattern-to-design-the-interface-of-an-webpage Now I am confused, First post suggested me that both are similar, just a difference that in N-tier, the tier are physically and logically separated and one layer has access to the one above and below it but not all the layers. I think ASP.net used 3 Tier architecture while developing applications or Web applications. Where as frameworks like Zend, Symphony they use MVC. I just want to stick to a pattern that is best suitable for WebProject Development? May be this is a very silly confusion? But if someone could clear this confusion, that would be very greatful?

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• AJAX UpdatePanel.Visible Property not working with Javascript

  - by Ahmet Altun

  I have code below. I want to hide the update panel by using Javascript (without going to server) when the user clicks Hide button. Although javascript funciton seems to be working fine in debugging, it does not hide! <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" % <script type="text/javascript" language="javascript"> function Show() { document.getElementById("UpdatePanel1").Visible = true; } function Hide() { document.getElementById("UpdatePanel1").Visible = false; } </script> <asp:ScriptManager ID="ScriptManager1" runat="server"> </asp:ScriptManager> <asp:Button ID="btnShow" runat="server" Text="Show" OnClientClick="Show(); return false;" /> <asp:Button ID="BtnHide" runat="server" Text="Hide" OnClientClick="Hide(); return false;" /> <asp:UpdatePanel ID="UpdatePanel1" runat="server"> <ContentTemplate> <br /> <asp:TextBox ID="TextBox1" runat="server" TextMode="MultiLine"></asp:TextBox> <br /> <asp:Button ID="btnSubmit" runat="server" Text="Gönder" onclick="btnSubmit_Click" /> <br /> </ContentTemplate> </asp:UpdatePanel> </div> </form>

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• best REGEXP friendly Text Editors + most powerful REGEXP syntax?

  - by John

  I am fluent with Microsoft Visual 2005 regular expressions and they are a big time saver. I seem to learn them best by having a vaguely organized cheat sheet thrown at me, at which point I read just a little and play with them until I understand what's going on. That learning approach has worked well for me, for now. I would really like to take this to the next level though. Basically -- What is the REGEXP convention that is generally regarded as the most open-ended and powerful? VS2005 Regexps seem kind of gimped, so maybe I'm a kid playing in a sandbox. Are there text editors out there that can perform a highlight all matches, list lines containing string, or some kind of powerful function like that in conjunction with the very strongest REGEXP language? If not I can just use multiple programs and a weird technique but I'd like to avoid that. I wonder if a stronger REGEXP language or a "stronger" regEXP writer might be able to have his search match all results on all lines even by clicking a "find next" by adding some simple criteria to the search. Anyway, please provide advice!

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• Firefox handles xxx.submit(), Safari doesn't ... what can be done?

  - by Prairiedogg

  I'm trying to make a pull down menu post a form when the user selects (releases the mouse) on one of the options from the menu. This code works fine in FF but Safari, for some reason, doesn't submit the form. I re-wrote the code using jquery to see if jquery's .submit() implementation handled the browser quirks better. Same result, works in FF doesn't work in safari. The following snippets are from the same page, which has some django template language mixed in. Here's the vanilla js attempt: function formSubmit(lang) { if (lang != '{{ LANGUAGE_CODE }}') { document.getElementById("setlang_form").submit(); } } Here's the jquery attempt: $(document).ready(function() { $('#lang_submit').hide() $('#setlang_form option').mouseup(function () { if ($(this).attr('value') != '{{ LANGUAGE_CODE }}') { $('#setlang_form').submit() } }); }); and here's the form: <form id="setlang_form" method="post" action="{% url django.views.i18n.set_language %}"> <fieldset> <select name="language"> {% for lang in interface_languages %} <option value="{{ lang.code }}" onmouseup="formSubmit('{{ lang.name }}')" {% ifequal lang.code LANGUAGE_CODE %}selected="selected"{% endifequal %}>{{ lang.name }}</option> {% endfor %} </select> </fieldset> </form> My question is, how can I get this working in Safari?

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• Java extends classes - Share the extended class fields within the super class.

  - by Bastan

  Straight to the point... I have a class public class P_Gen{ protected String s; protected Object oP_Gen; public P_Gen(String str){ s = str; oP_Gen = new Myclass(this); } } Extended class: public class P extends P_Gen{ protected Object oP; public P(String str){ oP = new aClass(str); super(str); } } MyClass: public class MyClass{ protected Object oMC; public MyClass(P extendedObject){ oMc = oP.getSomething(); } } I came to realize that MyClass can only be instantiated with (P_Gen thisObject) as opposed to (P extendedObject). The situation is that I have code generated a bunch of classes like P_Gen. For each of them I have generated a class P which would contains my P specific custom methods and fields. When I'll regenerate my code in the future, P would not be overwritten as P_Gen would. ** So what happened in my case???!!!... I realized that MyClass would beneficiate from the info stored in P in addition to only P_Gen. Would that possible? I know it's not JAVA "realistic" since another class that extends P_Gen might not have the same fields... BY DESIGN, P_Gen will not be extended by anything but P.... And that's where it kinda make sens. :-) at least in other programming language ;-) In other programming language, it seems like P_Gen.this === P.this, in other word, "this" becomes a combination of P and P_Gen. Is there a way to achieve this knowing that P_Gen won't be extended by anything than P?

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• C++ STL Map vs Vector speed

  - by sub

  In the interpreter for my experimental programming language I have a symbol table. Each symbol consists of a name and a value (the value can be e.g.: of type string, int, function, etc.). At first I represented the table with a vector and iterated through the symbols checking if the given symbol name fitted. Then I though using a map, in my case map<string,symbol>, would be better than iterating through the vector all the time but: It's a bit hard to explain this part but I'll try. If a variable is retrieved the first time in a program in my language, of course its position in the symbol table has to be found (using vector now). If I would iterate through the vector every time the line gets executed (think of a loop), it would be terribly slow (as it currently is, nearly as slow as microsoft's batch). So I could use a map to retrieve the variable: SymbolTable[ myVar.Name ] But think of the following: If the variable, still using vector, is found the first time, I can store its exact integer position in the vector with it. That means: The next time it is needed, my interpreter knows that it has been "cached" and doesn't search the symbol table for it but does something like SymbolTable.at( myVar.CachedPosition ). Now my (rather hard?) question: Should I use a vector for the symbol table together with caching the position of the variable in the vector? Should I rather use a map? Why? How fast is the [] operator? Should I use something completely different?

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• Data Warehouse: Modelling a future schedule

  - by Pat

  I'm creating a DW that will contain data on financial securities such as bonds and loans. These securities are associated with payment schedules. For example, a bond could pay quarterly, while a mortage would usually pay monthly (sometimes biweekly). The payment schedule is created when the security is traded and, in the majority of cases, will remain unchanged. However, the design would need to accomodate those cases where it does change. I'm currently attempting to model this data and I'm having difficulty coming up with a workable design. One of the most commonly queried fields is "next payment date". Users often want to know when a security will pay next. Therefore, I want to make it as easy as possible for them to get the next payment date and amount for each security. Also, users often run historical queries in which case they'd want the next payment date and amount as of a specific point in time. For example, they may want to look back at 1/31/09 and query the next payment dates (which would usually be in February 2009 for mortgages). It's also common that they want to query a security's entire payment schedule, which might consist of 360 records (30 year mortgage x 12 payments/year). Since the next payment date and amount would be changing each month or even biweekly, these fields wouldn't seem to fit into a slow-changing dimension very well. It would probably make more sense to use a fact table, but I'm unsure of how to model it. Any ideas would be greatly appreciated.

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