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• How to read pair in freemarker

  - by Lukasz Rys

  Ok i'm having little trouble with reading pair. So I'm creating my pair private Pair<Integer, Integer> count(somethink) { int c1 = 2; int c2 = 4; return new Pair<Integer, Integer>(c1, c2); } And 'sending' it to ftl via java mv.addObject("counted", count(somethink)); I won't write everythink how it sends because I dont think it really matters with my issue. So i'm recieving it in "ftl". Then i was trying to 'read' it <#list counted?keys as key> <a href="#offerOrderTab"><@spring.message "someMsg"/>(${key}/${counted[key]})</a> </#list> After then i'm getting error Expecting a string, date or number here, Expression x is instead a freemarker.ext.beans.SimpleMethodModel As i suppose you dont iterate pairs (or I'm wrong?) i know its pair that contains only one key and one value but still i have to do send it that way and I thought its goin be to similar to iterating through map, in java i would use pair.first() and pair.second() but it doesn't work in ftl (ye i know it shouldnt work). I also tried to cast it to String by using ?string but it didnt work too

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• Performance Comparison of Shell Scripts vs high level interpreted langs (C#/Java/etc.)

  - by dferraro

  Hi all, First - This is not meant to be a 'which is better, ignorant nonionic war thread'... But rather, I generally need help in making an architecture decision / argument to put forward to my boss. Skipping the details - I simply just would love to know and find the results of anyone who has done some performance comparisons of Shell vs [Insert General Purpose Programming Language (interpreted) here), such as C# or Java... Surprisingly, I have spent some time on Google on searching here to not find any of this data. Has anyone ever done these comparisons, in different use-cases; hitting a database like in a XYX # of loops doing different types of SQL (Oracle pref, but MSSQL would do) queries such as any of the CRUD ops - and also not hitting database and just regular 50k loop type comparison doing different types of calculations, and things of that nature? In particular - for right now, I need to a comparison of hitting an Oracle DB from a shell script vs, lets say C# (again, any GPPL thats interpreted would be fine, even the higher level ones like Python). But I also need to know about standard programming calculations / instructions/etc... Before you ask 'why not just write a quick test yourself? The answer is: I've been a Windows developer my whole life/career and have very limited knowledge of Shell scripting - not to mention *nix as a whole.... So asking the question on here from the more experienced guys would be grealty beneficial, not to mention time saving as we are in near perputual deadline crunch as it is ;). Thanks so much in advance,

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• How is the C++ synthesized move constructor affected by volatile and virtual members?

  - by user1827766

  Look at the following code: struct node { node(); //node(const node&); //#1 //node(node&&); //#2 virtual //#3 ~node (); node* volatile //#4 next; }; main() { node m(node()); //#5 node n=node(); //#6 } When compiled with gcc-4.6.1 it produces the following error: g++ -g --std=c++0x -c -o node.o node.cc node.cc: In constructor node::node(node&&): node.cc:3:8: error: expression node::next has side-effects node.cc: In function int main(): node.cc:18:14: note: synthesized method node::node(node&&) first required here As I understand the compiler fails to create default move or copy constructor on line #6, if I uncomment either line #1 or #2 it compiles fine, that is clear. The code compiles fine without c++0x option, so the error is related to default move constructor. However, what in the node class prevents default move constructor to be created? If I comment any of the lines #3 or #4 (i.e. make the destructor non-virtual or make data member non-volatile) it compiles again, so is it the combination of these two makes it not to compile? Another puzzle, line #5 does not cause an compilation error, what is different from line #6? Is it all specific for gcc? or gcc-4.6.1?

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• What causes markup-controls to be null?

  - by Earlz

  Ok, I have a very strange problem. I have a regular UserControl with some controls in the markup. At Page_Load these controls are still null. And I have tried EnsureChildControls It is laid out like this: Masterpage - Page - mycontrol1 - mycontrol2 - problemcontrol ProblemControl is where the controls are null. MyControl1 contains MyControl2. MyControl2 is another UserControl which contains ProblemControl in it's markup. Masterpage is nothing special and Page contains MyControl1 in it's markup. The only oddity is that ProblemControl is created dynamically at Page_Init. Everything works fine until I get to ProblemControl where none of the controls are being created. ProblemControl has the proper things all set such as the Page and Parent property. I do not see any problems. The source code for all of these(except ProblemControl) is pretty extensive, so I'm hoping someone can just give me some troubleshooting tips for this problem and if anyone has encountered it before. Also, I can place ProblemControl on another Page control and it will work fine, it's something about mycontrol1 and/or mycontrol2. But we've never had any problems with mycontrol1 and mycontrol2 doesn't have anything I can see wrong with it. (which I've been tediously analyzing for the past few hours). Has anyone else had this same problem? Are there any common things to check for?

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• Using the JPA Criteria API, can you do a fetch join that results in only one join?

  - by Shaun

  Using JPA 2.0. It seems that by default (no explicit fetch), @OneToOne(fetch = FetchType.EAGER) fields are fetched in 1 + N queries, where N is the number of results containing an Entity that defines the relationship to a distinct related entity. Using the Criteria API, I might try to avoid that as follows: CriteriaBuilder builder = entityManager.getCriteriaBuilder(); CriteriaQuery<MyEntity> query = builder.createQuery(MyEntity.class); Root<MyEntity> root = query.from(MyEntity.class); Join<MyEntity, RelatedEntity> join = root.join("relatedEntity"); root.fetch("relatedEntity"); query.select(root).where(builder.equals(join.get("id"), 3)); The above should ideally be equivalent to the following: SELECT m FROM MyEntity m JOIN FETCH myEntity.relatedEntity r WHERE r.id = 3 However, the criteria query results in the root table needlessly being joined to the related entity table twice; once for the fetch, and once for the where predicate. The resulting SQL looks something like this: SELECT myentity.id, myentity.attribute, relatedentity2.id, relatedentity2.attribute FROM my_entity myentity INNER JOIN related_entity relatedentity1 ON myentity.related_id = relatedentity1.id INNER JOIN related_entity relatedentity2 ON myentity.related_id = relatedentity2.id WHERE relatedentity1.id = 3 Alas, if I only do the fetch, then I don't have an expression to use in the where clause. Am I missing something, or is this a limitation of the Criteria API? If it's the latter, is this being remedied in JPA 2.1 or are there any vendor-specific enhancements? Otherwise, it seems better to just give up compile-time type checking (I realize my example doesn't use the metamodel) and use dynamic JPQL TypedQueries.

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• Dynamic Select boxes page load

  - by Chris

  Hello, I have a dynamic chained select box that I am attempting to show the value of on a page load. In my chained select box, it will default to the first option within the select box on page load, could anyone provide assitance? I stumbled upon this thread, but I can't seem to translate what they are doing with that answer to my language of CF. Dynamic chained drop downs on page refresh Here is the JS script I am using. function dynamicSelect(id1, id2) { // Feature test to see if there is enough W3C DOM support if (document.getElementById && document.getElementsByTagName) { // Obtain references to both select boxes var sel1 = document.getElementById(id1); var sel2 = document.getElementById(id2); // Clone the dynamic select box var clone = sel2.cloneNode(true); // Obtain references to all cloned options var clonedOptions = clone.getElementsByTagName("option"); // Onload init: call a generic function to display the related options in the dynamic select box refreshDynamicSelectOptions(sel1, sel2, clonedOptions); // Onchange of the main select box: call a generic function to display the related options in the dynamic select box sel1.onchange = function() { refreshDynamicSelectOptions(sel1, sel2, clonedOptions); } } } function refreshDynamicSelectOptions(sel1, sel2, clonedOptions) { // Delete all options of the dynamic select box while (sel2.options.length) { sel2.remove(0); } // Create regular expression objects for "select" and the value of the selected option of the main select box as class names var pattern1 = /( |^)(select)( |$)/; var pattern2 = new RegExp("( |^)(" + sel1.options[sel1.selectedIndex].value + ")( |$)"); // Iterate through all cloned options for (var i = 0; i < clonedOptions.length; i++) { // If the classname of a cloned option either equals "select" or equals the value of the selected option of the main select box if (clonedOptions[i].className.match(pattern1) || clonedOptions[i].className.match(pattern2)) { // Clone the option from the hidden option pool and append it to the dynamic select box sel2.appendChild(clonedOptions[i].cloneNode(true)); } } } Thanks so much for any assistance

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• SQL with HAVING and temp table not working in Rails

  - by chrisrbailey

  I can't get the following SQL query to work quite right in Rails. It runs, but it fails to do the "HAVING row_number = 1" part, so I'm getting all the records, instead of just the first record from each group. A quick description of the query: it is finding hotel deals with various criteria, and in particular, priortizing them being paid, and then picking the one with the highest dealrank. So, if there are paid deal(s), it'll take the highest one of those (by dealrank) first, if no paid deals, it takes the highest dealrank unpaid deal for each hotel. Using MAX(dealrank) or something similar does not work as a way to pick off the first row of each hotel group, which is why I have the enclosing temptable and the creation of the row_number column. Here's the query: SELECT *, @num := if(@hid = hotel_id, @num + 1, 1) as row_number, @hid := hotel_id as dummy FROM ( SELECT hotel_deals.*, affiliates.cpc, (CASE when affiliates.cpc 0 then 1 else 0 end) AS paid FROM hotel_deals INNER JOIN hotels ON hotels.id = hotel_deals.hotel_id LEFT OUTER JOIN affiliates ON affiliates.id = hotel_deals.affiliate_id WHERE ((hotel_deals.percent_savings = 0) AND (hotel_deals.booking_deadline = ?)) GROUP BY hotel_deals.hotel_id, paid DESC, hotel_deals.dealrank ASC) temptable HAVING row_number = 1 I'm currently using Rails' find_by_sql to do this, although I've also tried putting it into a regular find using the :select, :from, and :having parts (but :having won't get used unless you have a :group as well). If there is a different way to write this query, that'd be good to know too. I am using Rails 2.3.5, MySQL 5.0.x.

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• IP Address Validation Help

  - by Zubair1

  I am using this IP Validation Function that I came across while browsing, it has been working well until today i ran into a problem. For some reason the function won't validate this IP as valid: 203.81.192.26 I'm not too great with regular expressions, so would appreciate any help on what could be wrong. If you have another function, I would appreciate if you could post that for me. The code for the function is below: public static function validateIpAddress($ip_addr) { global $errors; $preg = '#^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}' . '(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$#'; if(preg_match($preg, $ip_addr)) { //now all the intger values are separated $parts = explode(".", $ip_addr); //now we need to check each part can range from 0-255 foreach($parts as $ip_parts) { if(intval($ip_parts) > 255 || intval($ip_parts) < 0) { $errors[] = "ip address is not valid."; return false; } return true; } return true; } else { $errors[] = "please double check the ip address."; return false; } }

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• Spring annotation-based container configuration context:include & exclude filters

  - by lisak

  Hey, first off I point to the similar question. I spent more than an hour to set this up, but PathMatchingResourcePatternResolver still scans everything. I have one common.xml (that is imported from specific.xml) and a specific.xml bean definition file. The context is loaded from specific.xml. In common.xml there is this element: <context:component-scan base-package="cz.instance.transl"> <context:exclude-filter type="aspectj" expression="cz.instance.transl.model..* &amp;&amp; cz.instance.transl.service..* &amp;&amp; cz.instance.transl.hooks..*"/> </context:component-scan> Where classes in packages like cz.instance.transl.service.* should not be subject of scanning, but everything else in here cz.instance.transl.* should be scanned through. But PathMatchingResourcePatternResolver marks everything as matching resources. It is the same with regex. BTW: in xml style configuration, one can have many components that share a common.xml beans via "import resource" when loading context. How this is done when Annotation-based container configuration is used ?

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• Mono Develop 2.4.1 + linq error.

  - by Nev_Rahd

  I just started to learn Mono Develop Installed Mono Develop 2.4.1 and trial version of Mono Touch. my Code: using System; using System.Xml.Linq; using System.Collections.Generic; namespace RSSReader { public static class RSSRepository { public static IList<FeedItem> GetFeeds(string url) { XDocument rssFeed = XDocument.Load(url); Console.Write(rssFeed.ToString()); var feeds = new List<FeedItem>(); try { var query = from item in rssFeed.Descendants("item") select new FeedItem { Title = item.Element("title").Value, Published = DateTime.Parse(item.Element("pubDate").Value), Url = item.Element("link").Value }; feeds = query.ToList(); } catch (Exception ex){ Console.WriteLine(ex.Message); } return feeds; } } } This is throwing an error: An implementation of 'select' query expression pattern could not be found. Are you missing 'System.linq' using directive or 'System.Core.dll' assembly reference? I got both references to System.Xml.Linq and System.Core What am i missing ?

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• Apache friendly urls

  - by HaukurHaf

  Hi everyone. I've got a small CMS system written in PHP and running on Apache. The format of the URLs this CMS system uses/generates is: /display.php?PageID=xxx where xxx is just some integer number. As you can see, those URLs are not very friendly, neither for users nor search engines. I believe that using mod_rewrite (or something like that) and .htaccess files I should be able to configure Apache for URL-rewriting. I have searched for information about this before but I did not find any easy method to do this, it always involved messing with regular expressions, which I'm not very familiar with. Since the website in question is really simple and small, just 5-10 different pages, I would really like to be able to just hard-code the configuration, without any special rules or regexps. I'd just like to map a friendly URL to an actual URL, perhaps like this: /about = /display.php?PageID=44 /products = /display.php?PageID=34 etc. Is it possible to configure the mod_rewrite plugin in a basic way like this? Could someone explain the easiest method to do this? Explain it to me as if I was a child :-) Thanks in advance!

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• Error compiling basic java code

  - by Michael Younani

  New to java. Practicing coding by following a book. Heres my code: class Motorcycle { //Three instance variables - make and color are strings. while a boolean refers to TRUE OR FLASE(in this case off or on) String make; String color; boolean engineState; void startEngine() { if (engineState == true) System.out.print("The engine is already on."); else { engineState = true; System.out.print("The engine is now on."); } void showAtts() { System.out.print("This motorcycle is a " + color + " " + make); if (engineState ==true) System.out.print("The engine is on."); else System.out.print("The engine is off."); } } } When I compile I get 2 errors: 1) illegal start of expression 2) ; expected I can't pin point the problem. If anyone can direct me or hint me please do.

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• SQL Server 2008 - Full Text Query

  - by user208662

  Hello, I have two tables in a SQL Server 2008 database in my company. The first table represents the products that my company sells. The second table contains the product manufacturer’s details. These tables are defined as follows: Product ------- ID Name ManufacturerID Description Manufacturer ------------ ID Name As you can imagine, I want to make this as easy as possible for our customers to query this data. However, I’m having problems writing a forgiving, yet powerful search query. For instance, I’m anticipating people to search based on phonetical spellings. Because of this, the data may not match the exact data in my database. In addition, I think some individuals will search by manufacturer’s name first, but I want the matching product names to appear first. Based on these requirements, I’m currently working on the following query: select p.Name as 'ProductName', m.Name as 'Manufacturer', r.Rank as 'Rank' from Product p inner join Manufacturer m on p.ManufacturerID=m.ID inner join CONTAINSTABLE(Product, Name, @searchQuery) as r Oddly, this query is throwing an error. However, I have no idea why. Squiggles appear to the right of the last parenthesis in management studio. The tool tip says "An expression of non-boolean type specified in a context where a condition is expected". I understand what this statement means. However, I guess I do not know how COntainsTable works. What am I doing wrong? Thank you

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• Adding custom UITableViewCell crashes the simulator.

  - by nevva

  Im trying to build my application using a custom UITableViewCell. This is the code in my UIViewController that adds the viewCell to the table: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"------- Tableview --------"); static NSString *MyIdentifier = @"MyIdentifier"; MyIdentifier = @"aCellIdentifier"; MyTableCell *cell = (MyTableCell *)[tableView dequeueReusableCellWithIdentifier:MyIdentifier]; if(cell == nil) { NSArray *[[NSBundle mainBundle] loadNibNamed:@"tblCellView" owner:self options:nil]; cell = tblCell; } [cell setLabelText:[NSString stringWithFormat:@"indexpath.row: %d", indexPath.row]]; //cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:MyIdentifier] autorelease]; return cell; } if i uncomment the line above "return cell" it returns a regular UITableViewCell without any errors, but as soon as i try to implement my custom cell it crashes with this error: ------- Tableview -------- 2010-04-23 11:17:33.163 SogetGolf[26935:40b] * Assertion failure in -[UITableView _createPreparedCellForGlobalRow:withIndexPath:], /SourceCache/UIKit_Sim/UIKit-984.38/UITableView.m:4709 2010-04-23 11:17:33.164 SogetGolf[26935:40b] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath:' 2010-04-23 11:17:33.165 SogetGolf[26935:40b] Stack: ( ... I have configured the .xib file as one should with the proper outlets. And the identifier of the UITableViewCell corresponds with name im trying to load from NSBundle

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• "'Objects' may not respond to 'functions'" warnings.

  - by Andrew

  Hello all, for the last couple of weeks I've finally gotten into Obj-C from regular C and have started my first app. I've watched tutorials and read through a book along with a lot of webpages, but I know I've only just begun. Anyway, for most of the night and this morning, I've been trying to get this code to work, and now that it will compile, I have a few warnings. I've searched and found similar problems with solutions, but still no dice. What I'm trying to do is put an array made from a txt document into the popup list in a combo box. AwesomeBoxList.h: #import <Cocoa/Cocoa.h> @interface AwesomeBoxList : NSObject { IBOutlet NSComboBox *ComboBoz; } -(NSArray *) getStringzFromTxtz; - (void) awesomeBoxList; @end AwesomeBoxList.m: #import "AwesomeBoxList.h" @implementation AwesomeBoxList -(NSArray *)getStringzFromTxtz { ... return combind; } - (void) awesomeBoxList { [ComboBoz setUsesDataSource:YES]; [ComboBoz setDataSource: [ComboBoz getStringzFromTxtz]: //'NSComboBox' may not respond to 'getStringzFromTxtz' [ComboBoz comboBox:(NSComboBox *)ComboBoz objectValueForItemAtIndex: [ComboBoz numberOfItemsInComboBox:(NSComboBox *)ComboBoz]]]; /*'NSComboBox' may not respond to '-numberOfItemsInComboBox:' 'NSComboBox' may not respond to '-comboBox:objectValueForItemAtIndex:' 'NSComboBox' may not respond to '-setDataSource:' */ } @end So, with all of these errors and my still shallow knowledge of Obj-C, I must be making some sort of n00b mistake. Thanks for the help.

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• Scalably processing large amount of comlpicated database data in PHP, many times a day.

  - by Eph

  I'm soon to be working on a project that poses a problem for me. It's going to require, at regular intervals throughout the day, processing tens of thousands of records, potentially over a million. Processing is going to involve several (potentially complicated) formulas and the generation of several random factors, writing some new data to a separate table, and updating the original records with some results. This needs to occur for all records, ideally, every three hours. Each new user to the site will be adding between 50 and 500 records that need to be processed in such a fashion, so the number will not be steady. The code hasn't been written, yet, as I'm still in the design process, mostly because of this issue. I know I'm going to need to use cron jobs, but I'm concerned that processing records of this size may cause the site to freeze up, perform slowly, or just piss off my hosting company every three hours. I'd like to know if anyone has any experience or tips on similar subjects? I've never worked at this magnitude before, and for all I know, this will be trivial to the server and not pose much of an issue. As long as ALL records are processed before the next three hour period occurs, I don't care if they aren't processed simultaneously (though, ideally, all records belonging to a specific user should be processed in the same batch), so I've been wondering if I should process in batches every 5 minutes, 15 minutes, hour, whatever works, and how best to approach this (and make it scalable in a way that is fair to all users)?

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• How do I authenticate an ADO.NET Data Service?

  - by lsb

  Hi! I've created an ADO.Net Data Service hosted in a Azure worker role. I want to pass credentials from a simple console client to the service then validate them using a QueryInterceptor. Unfortunately, the credentials don't seem to be making it over the wire. The following is a simplified version of the code I'm using, starting with the DataService on the server: using System; using System.Data.Services; using System.Linq.Expressions; using System.ServiceModel; using System.Web; namespace Oslo.Worker { [ServiceBehavior(AddressFilterMode = AddressFilterMode.Any)] public class AdminService : DataService<OsloEntities> { public static void InitializeService( IDataServiceConfiguration config) { config.SetEntitySetAccessRule("*", EntitySetRights.All); config.SetServiceOperationAccessRule("*", ServiceOperationRights.All); } [QueryInterceptor("Pairs")] public Expression<Func<Pair, bool>> OnQueryPairs() { // This doesn't work!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! if (HttpContext.Current.User.Identity.Name != "ADMIN") throw new Exception("Ooops!"); return p => true; } } } Here's the AdminService I'm using to instantiate the AdminService in my Azure worker role: using System; using System.Data.Services; namespace Oslo.Worker { public class AdminHost : DataServiceHost { public AdminHost(Uri baseAddress) : base(typeof(AdminService), new Uri[] { baseAddress }) { } } } And finally, here's the client code. using System; using System.Data.Services.Client; using System.Net; using Oslo.Shared; namespace Oslo.ClientTest { public class AdminContext : DataServiceContext { public AdminContext(Uri serviceRoot, string userName, string password) : base(serviceRoot) { Credentials = new NetworkCredential(userName, password); } public DataServiceQuery<Order> Orders { get { return base.CreateQuery<Pair>("Orders"); } } } } I should mention that the code works great with the signal exception that the credentials are not being passed over the wire. Any help in this regard would be greatly appreciated! Thanks....

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• Tell bots apart from human visitors for stats?

  - by Pekka

  I am looking to roll my own simple web stats script. The only major obstacle on the road, as far as I can see, is telling human visitors apart from bots. I would like to have a solution for that which I don't need to maintain on a regular basis (i.e. I don't want to update text files with bot-related User-agents). Is there any open service that does that, like Akismet does for spam? Or is there a PHP project that is dedicated to recognizing spiders and bots and provides frequent updates? To clarify: I'm not looking to block bots. I do not need 100% watertight results. I just want to exclude as many as I can from my stats. In know that parsing the user-Agent is an option but maintaining the patterns to parse for is a lot of work. My question is whether there is any project or service that does that already. Bounty: I thought I'd push this as a reference question on the topic. The best / most original / most technically viable contribution will receive the bounty amount.

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• Applying MVVM to ASP.NET

  - by Moussa

  Hi everyone, I am learning MVVM and i want to use it with ASP.NET. Some of the examples that i found on the internet uses XAML for the view. Is there a way to use a regular ASP.NET page instead of XAML for the view? Here is a XAML example: <UserControl x:Class="MVVMExample.DetailView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> <Grid x:Name="LayoutRoot" Background="White" DataContext="{Binding CurrentContact}"> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition/> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <TextBlock Text="Name:" HorizontalAlignment="Right" Margin="5"/> <TextBlock Text="{Binding FullName}" HorizontalAlignment="Left" Margin="5" Grid.Column="1"/> <TextBlock Text="Phone:" HorizontalAlignment="Right" Margin="5" Grid.Row="1"/> <TextBlock Text="{Binding PhoneNumber}" HorizontalAlignment="Left" Margin="5" Grid.Row="1" Grid.Column="1"/> </Grid> </UserControl> Thank you for your time.

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• In Java, is there a gain in using interfaces for complex models?

  - by Gnoupi

  The title is hardly understandable, but I'm not sure how to summarize that another way. Any edit to clarify is welcome. I have been told, and recommended to use interfaces to improve performances, even in a case which doesn't especially call for the regular "interface" role. In this case, the objects are big models (in a MVC meaning), with many methods and fields. The "good use" that has been recommended to me is to create an interface, with its unique implementation. There won't be any other class implementing this interface, for sure. I have been told that this is better to do so, because it "exposes less" (or something close) to the other classes which will use methods from this class, as these objects are referring to the object from its interface (all public method from the implementation being reproduced in the interface). This seems quite strange to me, as it seems like a C++ use to me (with header files). There I see the point, but in Java? Is there really a point in making an interface for such unique implementation? I would really appreciate some clarifications on the topic, so I could justify not following such kind of behavior, and the hassle it creates from duplicating all declarations.

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• Python vs all the major professional languages [closed]

  - by Matt

  I've been reading up a lot lately on comparisons between Python and a bunch of the more traditional professional languages - C, C++, Java, etc, mainly trying to find out if its as good as those would be for my own purposes. I can't get this thought out of my head that it isn't good for 'real' programming tasks beyond automation and macros. Anyway, the general idea I got from about two hundred forum threads and blog posts is that for general, non-professional-level progs, scripts, and apps, and as long as it's a single programmer (you) writing it, a given program can be written quicker and more efficiently with Python than it could be with pretty much any other language. But once its big enough to require multiple programmers or more complex than a regular person (read: non-professional) would have any business making, it pretty much becomes instantly inferior to a million other languages. Is this idea more or less accurate? (I'm learning Python for my first language and want to be able to make any small app that I want, but I plan on learning C eventually too, because I want to get into driver writing eventually. So I've been trying to research each ones strengths and weaknesses as much as I can.) Anyway, thanks for any input

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• trouble with state monad composition

  - by user1308560

  I was trying out the example given at http://www.haskell.org/haskellwiki/State_Monad#Complete_and_Concrete_Example_1 How this makes the solution composible is beyond my understanding. Here is what I tried but I get compile errors as follows: Couldn't match expected type `GameValue -> StateT GameState Data.Functor.Identity.Identity b0' with actual type `State GameState GameValue' In the second argument of `(>>=)', namely `g2' In the expression: g1 >>= g2 In an equation for `g3': g3 = g1 >>= g2 Failed, modules loaded: none. Here is the code: See the end lines module StateGame where import Control.Monad.State type GameValue = Int type GameState = (Bool, Int) -- suppose I want to play one game after the other g1 = playGame "abcaaacbbcabbab" g2 = playGame "abcaaacbbcabb" g3 = g1 >>= g2 m2 = print $ evalState g3 startState playGame :: String -> State GameState GameValue playGame [] = do (_, score) <- get return score playGame (x:xs) = do (on, score) <- get case x of 'a' | on -> put (on, score + 1) 'b' | on -> put (on, score - 1) 'c' -> put (not on, score) _ -> put (on, score) playGame xs startState = (False, 0) main str = print $ evalState (playGame str) startState

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• Performance of stored proc when updating columns selectively based on parameters?

  - by kprobst

  I'm trying to figure out if this is relatively well-performing T-SQL (this is SQL Server 2008). I need to create a stored procedure that updates a table. The proc accepts as many parameters as there are columns in the table, and with the exception of the PK column, they all default to NULL. The body of the procedure looks like this: CREATE PROCEDURE proc_repo_update @object_id bigint ,@object_name varchar(50) = NULL ,@object_type char(2) = NULL ,@object_weight int = NULL ,@owner_id int = NULL -- ...etc AS BEGIN update object_repo set object_name = ISNULL(@object_name, object_name) ,object_type = ISNULL(@object_type, object_type) ,object_weight = ISNULL(@object_weight, object_weight) ,owner_id = ISNULL(@owner_id, owner_id) -- ...etc where object_id = @object_id return @@ROWCOUNT END So basically: Update a column only if its corresponding parameter was provided, and leave the rest alone. This works well enough, but as the ISNULL call will return the value of the column if the received parameter was null, will SQL Server optimize this somehow? This might be a performance bottleneck on the application where the table might be updated heavily (insertion will be uncommon so the performance there is not a problem). So I'm trying to figure out what's the best way to do this. Is there a way to condition the column expressions with something like CASE WHEN or something? The table will be indexed up the wazoo as well for read performance. Is this the best approach? My alternative at this point is to create the UPDATE expression in code (e.g. inline SQL) and execute it against the server. This would solve my doubts about performance, but I'd rather leave this in a stored proc if possible.

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• Custom Image Button and Radio/Toggle Button from Common Base Class

  - by Wonko the Sane

  Hi All, I would like to create a set of custom controls that are basically image buttons (it's a little more complex than that, but that's the underlying effect I'm going for) that I've seen a few different examples for. However, I would like to further extend that to also allow radio/toggle buttons. What I'd like to do is have a common abstract class called ImageButtonBase that has default implementations for ImageSource and Text, etc. That makes a regular ImageButton implementation pretty easy. The issue I am having is creating the RadioButton flavor of it. As I see it, there are at least three options: It would be easy to create something that derives from RadioButton, but then I can't use the abstract class I've created. I could change the abstract class to an interface, but then I lose the abstract implementations, and will in fact have duplication of code. I could derive from my abstract class, and re-implement the RadioButton-type properties and events (IsChecked, GroupName, etc.), but that certainly doesn't seem like a great idea. Note: I have seen http://stackoverflow.com/questions/2362641/how-to-get-a-group-of-toggle-buttons-to-act-like-radio-buttons-in-wpf, but what I want to do is a little more complex. I'm just wondering if anybody has an example of an implementation, or something that might be adapted to this kind of scenario. I can see pros and cons of each of the ideas above, but each comes with potential pitfalls. Thanks, wTs

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• Reusing named_scope to define another named_scope

  - by Sergei Kozlov

  The problem essence as I see it One day, if I'm not mistaken, I have seen an example of reusing a named_scope to define another named_scope. Something like this (can't remember the exact syntax, but that's exactly my question): named_scope :billable, :conditions => ... named_scope :billable_by_tom, :conditions => { :billable => true, :user => User.find_by_name('Tom') } The question is: what is the exact syntax, if it's possible at all? I can't find it back, and Google was of no help either. Some explanations Why I actually want it, is that I'm using Searchlogic to define a complex search, which can result in an expression like this: Card.user_group_managers_salary_greater_than(100) But it's too long to be put everywhere. Because, as far as I know, Searchlogic simply defines named_scopes on the fly, I would like to set a named_scope on the Card class like this: named_scope from_big_guys, { user_group_managers_salary_greater_than(100) } - this is where I would use that long Searchlogic method inside my named_scope. But, again, what would be the syntax? Can't figure it out. Resume So, is named_scope nesting (and I do not mean chaining) actually possible?

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