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• What's the correct place to share application logic in CakePHP?

  - by Pichan

  I guess simple answer to the question would be a component. Although I agree, I feel weird having to write a component for something so specific. For example, let's say I have a table of users. When a user is created, it should form a chain reaction of events, initiating different kinds of data related to the user all around the database. I figured it would be best to avoid directly manipulating the database from different controllers and instead pack all that neatly in a method. However since some logic needs to be accesed separately, I really can't have the whole package in a single method. Instead I thought it would be logical to break it up to smaller pieces(like $userModelOrController->createNew() and $candyStorageModelOrController->createNew()) that only interact with their respective database table. Now, if the logic is put to the model, it works great until I need to use other models. Of course it's possible, but when compared to loading models in a controller, it's not that simple. It's like a Cake developer telling me "Sure, it's possible if you want to do it that way but that's not how I would do it". Then, if the logic is put to the controller, I can access other models really easy through $this->loadModel(), but that brings me back to the previously explained situation since I need to be able to continue the chain reaction indefinitely. Accessing other controllers from a controller is possible, but again there doesn't seem to be any direct way of doing so, so I'm guessing I'm still not doing it right. By using a component this problem could be solved easily, since components are available to every controller I want. But like I wrote at the beginning, it feels awkward to create a component specifically for this one task. To me, components seem more like packages of extra functionality(like the core components) and not something to share controller-specific logic. Since I'm new to this whole MVC thing, I could've completely misunderstood the concept. Once again, I would be thankful if someone pointed me to the right direction :)

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• Speed comparison - Template specialization vs. Virtual Function vs. If-Statement

  - by Person

  Just to get it out of the way... Premature optimization is the root of all evil Make use of OOP etc. I understand. Just looking for some advice regarding the speed of certain operations that I can store in my grey matter for future reference. Say you have an Animation class. An animation can be looped (plays over and over) or not looped (plays once), it may have unique frame times or not, etc. Let's say there are 3 of these "either or" attributes. Note that any method of the Animation class will at most check for one of these (i.e. this isn't a case of a giant branch of if-elseif). Here are some options. 1) Give it boolean members for the attributes given above, and use an if statement to check against them when playing the animation to perform the appropriate action. Problem: Conditional checked every single time the animation is played. 2) Make a base animation class, and derive other animations classes such as LoopedAnimation and AnimationUniqueFrames, etc. Problem: Vtable check upon every call to play the animation given that you have something like a vector<Animation>. Also, making a separate class for all of the possible combinations seems code bloaty. 3) Use template specialization, and specialize those functions that depend on those attributes. Like template<bool looped, bool uniqueFrameTimes> class Animation. Problem: The problem with this is that you couldn't just have a vector<Animation> for something's animations. Could also be bloaty. I'm wondering what kind of speed each of these options offer? I'm particularly interested in the 1st and 2nd option because the 3rd doesn't allow one to iterate through a general container of Animations. In short, what is faster - a vtable fetch or a conditional?

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• Python logging in Django

  - by Jeff

  I'm developing a Django app, and I'm trying to use Python's logging module for error/trace logging. Ideally I'd like to have different loggers configured for different areas of the site. So far I've got all of this working, but one thing has me scratching my head. I have the root logger going to sys.stderr, and I have configured another logger to write to a file. This is in my settings.py file: sviewlog = logging.getLogger('MyApp.views.scans') view_log_handler = logging.FileHandler('C:\\MyApp\\logs\\scan_log.log') view_log_handler.setLevel(logging.INFO) view_log_handler.setFormatter(logging.Formatter('%(asctime)s %(name)-12s %(levelname)-8s %(message)s')) sviewlog.addHandler(view_log_handler) Seems pretty simple. Here's the problem, though: whatever I write to the sviewlog gets written to the log file twice. The root logger only prints it once. It's like addHandler() is being called twice. And when I put my code through a debugger, this is exactly what I see. The code in settings.py is getting executed twice, so two FileHandlers are created and added to the same logger instance. But why? And how do I get around this? Can anyone tell me what's going on here? I've tried moving the sviewlog logger/handler instantiation code to the file where it's used (since that actually seems like the appropriate place to me), but I have the same problem there. Most of the examples I've seen online use only the root logger, and I'd prefer to have multiple loggers.

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• BufferedImage.getGraphics() resulting in memory leak, is there a fix?

  - by user359202

  Hi friends, I'm having problem with some framework API calling BufferedImage.getGraphics() method and thus causing memory leak. What this method does is that it always calls BufferedImage.createGraphics(). On a windows machine, createGraphics() is handled by Win32GraphicsEnvironment which keeps a listeners list inside its field displayChanger. When I call getGraphics on my BufferedImage someChart, someChart's SurfaceManager(which retains a reference to someChart) is added to the listeners map in Win32GraphicsEnvironment, preventing someChart to be garbage collected. Nothing afterwards removes someChart's SurfaceManager from the listeners map. In general, the summarized path stopping a BufferedImage from being garbage collected, once getGraphics is called, is as follows: GC Root - localGraphicsEnvironment(Win32GraphicsEnvironment) - displayChanger(SunDisplayChanger) - listeners(Map) - key(D3DChachingSurfaceManager) - bImg(BufferedImage) I could have changed the framework's code so that after every called to BufferedImage.getGraphics(), I keep a reference to the BufferedImage's SurfaceManager. Then, I get hold of localGraphicsEnvironment, cast it to Win32GraphicsEnvironment, then call removeDisplayChangedListener() using the reference to the BufferedImage's SurfaceManager. But I don't think this is a proper way to solve the problem. Could someone please help me with this issue? Thanks a lot!

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• IPhone - Memory Management problems.

  - by user321721

  i am going over my code and trying to get a handle on proper memory management. This code: imageView = [[[UIImageView alloc] initWithImage:myImage] autorelease]; causes my application to crash. I am using multiple view controllers within a nav bar controller. The app works fine, i cant select a person from the first view controller (tableview) and it puts me to a list of that persons photos, i can then select a photo from that view controller (tableview) and move to a final view with a scrollview for viewing the photo. Once i hit back on the navbar the previous view loads (list of photos in a tableview) however the app crashes right before the row is deselected using this code: (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; if(RowSelected != nil) { [MainTableView deselectRowAtIndexPath:RowSelected animated:YES]; } } Row selected is stored when a the user clicks a row. If i leave the code as : imageView = [[UIImageView alloc] initWithImage:myImage]; The app runs fine. Am i doing something wrong? do i not need to autorelease this? Thanks!

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• PHP OAuth Twitter

  - by Sandhurst

  I have created a twitter app which I am using to post tweets. The problem that I am not able to resolve is everytime I have to allow access to my application. so lets say I need to tweet three messages, so all the three times I have to allow access to my app. I just need that once user has allowed access to my app, next time he should only be asked to allow acces is that when he/she relogins. Here's my code that I am using Share content on twitter"; include 'lib/EpiCurl.php'; include 'lib/EpiOAuth.php'; include 'lib/EpiTwitter.php'; include 'lib/secret.php'; $twitterObj = new EpiTwitter($consumer_key, $consumer_secret); $oauth_token = $_GET['oauth_token']; if($oauth_token == '') { $url = $twitterObj-getAuthorizationUrl(); echo ""; echo "Sign In with Twitter"; echo ""; } else { $twitterObj-setToken($_GET['oauth_token']); $token = $twitterObj-getAccessToken(); $twitterObj-setToken($token-oauth_token, $token-oauth_token_secret); $_SESSION['ot'] = $token-oauth_token; $_SESSION['ots'] = $token-oauth_token_secret; $twitterInfo= $twitterObj-get_accountVerify_credentials(); $twitterInfo-response; $username = $twitterInfo-screen_name; $profilepic = $twitterInfo-profile_image_url; include 'update.php'; } if(isset($_POST['submit'])) { $msg = $_REQUEST['tweet']; $twitterObj-setToken($_SESSION['ot'], $_SESSION['ots']); $update_status = $twitterObj-post_statusesUpdate(array('status' = $msg)); $temp = $update_status-response; header("Location: MessageStatus.html"); exit(); } ?

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• INSERT INTO ...SELECT syntax error in join operator

  - by user1477356

  I'm trying to write a shopping basket into a order + orderline in a sql database from C# asp.net. the orderline will contain a ordernumber, total price, productid, quantity etc. for every item in the basket. The order itself will contain the ordernumber as primary key and will be linked to the different lines through it. Everything worked fine yesterday, but now as i tried to use a SELECT command in the insert into statement to get things more dynamic i'm getting the above described syntax error. Does anybody know what's wrong with this statement: INSERT INTO [order] (klant_id,totaalprijs,btw,subtotaal,verzendkosten) SELECT klant.id , SUM(orderregel.totaalprijs) , SUM(orderregel.btw) , SUM(orderregel.totaalprijs) - SUM(orderregel.btw) , 7.50 FROM orderregel INNER JOIN klant ON [order].klant_id = klant.id WHERE klant.username = 'jerry' GROUP BY id; the ordernumber in the "order" table is on autonumber, in the asp codebehind there is a for each which handles the lines being written for every product, there's an index set on 0 outside of this loop and is heightened with 1 every end of it. The executenonquery of the order is only executed once at the beginning of the first loop and the lines are added after with MAX(ordernumber) as ordernumber. I hope i have provided enough information and somebody is capable of helping me. Thanks in advance!

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• guide for creating addins for Visual Studio 2010?

  - by JMarsch

  Hello: 2 questions actuall: Is there a good comprensive guide out there for creating add-ins for Visual Studio? Here's a weird specific problem -- I'm trying to get my add-in to load. The code that the wizard stubs into the OnConnect method will add it to the toolbar, but only if it passes this "if" statement: if (connectMode == ext_ConnectMode.ext_cm_UISetup) The problem is that connectMode never seems to equal ext_cm_UISetup. It always seems to equal ext_cm_AfterStartup, and My AddIn never appears on the toolbar. I could cheat and short-circuit the if, but since Visual Studio put that code there, I bet it's right, and I have something else wrong. According to the docs, the value should only ever be ext_cm_UISetup once -- the first time VS encounters the addin. So I probably need to somehow make VS forget about the add-in, but I can't find anywhere to do that. And by the way, isn't that exceptionally delicate? The reason I'm in this pickle is because I happened to get an exception on the first try, so now I can never try again?? Can't be right.

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• C++, Ifstream opens local file but not file on HTTP Server

  - by fammi

  Hi, I am using ifstream to open a file and then read from it. My program works fine when i give location of the local file on my system. for eg /root/Desktop/abc.xxx works fine But once the location is on the http server the file fails to open. for eg http://192.168.0.10/abc.xxx fails to open. Is there any alternate for ifstream when using a URL address? thanks. part of the code where having problem: bool readTillEof = (endIndex == -1) ? true : false; // Open the file in binary mode and seek to the end to determine file size ifstream file ( fileName.c_str ( ), ios::in|ios::ate|ios::binary ); if ( file.is_open ( ) ) { long size = (long) file.tellg ( ); long numBytesRead; if ( readTillEof ) { numBytesRead = size - startIndex; } else { numBytesRead = endIndex - startIndex + 1; } // Allocate a new buffer ptr to read in the file data BufferSptr buf (new Buffer ( numBytesRead ) ); mpStreamingClientEngine->SetResponseBuffer ( nextRequest, buf ); // Seek to the start index of the byte range // and read the data file.seekg ( startIndex, ios::beg ); file.read ( (char *)buf->GetData(), numBytesRead ); // Pass on the data to the SCE // and signal completion of request mpStreamingClientEngine->HandleDataReceived( nextRequest, numBytesRead); mpStreamingClientEngine->MarkRequestCompleted( nextRequest ); // Close the file file.close ( ); } else { // Report error to the Streaming Client Engine // as unable to open file AHS_ERROR ( ConnectionManager, " Error while opening file \"%s\"\n", fileName.c_str ( ) ); mpStreamingClientEngine->HandleRequestFailed( nextRequest, CONNECTION_FAILED ); } }

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• Echoing variable construct instead of content

  - by danp

  I'm merging two different versions of a translations array. The more recent version has a lot of changes, over several thousand lines of code. To do this, I loaded and evaluated the new file (which uses the same structure and key names), then loaded and evaluated the older version, overwriting the new untranslated values in the array with the values we already have translated. So far so good! However, I want to be able to echo out the constructor for this new merged array so I can cut and paste it into the new translation file, and have job done (apart from completing the rest of the translations..). The code looks like this (lots of different keys, not just index): $lang["index"]["chart1_label1"] = "Subscribed"; $lang["index"]["chart1_label2"] = "Unsubscribed"; And the old.. $lang["index"]["chart1_label1"] = "Subscrito"; $lang["index"]["chart1_label2"] = "Não subscrito"; After loading the two files, I end up with a merged $lang array, which I then want to echo out in the same form, so it can be used by the project. However, when I do something like this.. foreach ($lang as $key => $value) { if (is_array($value)) { foreach ($value as $key2 => $value2) { echo "$lang['".$key."']"; // ... etc etc } } } ..obviously I get "ArrayIndex" etc etc instead of "$lang". How to echo out $lang without it being evaluated..? Once this is working, can add in the rest of the brackets etc (I realise they are missing), but just want to make this part work first. If there's a better way to do this, all ears too! Thanks.

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• How to configure multiple mappings using FluentHibernate?

  - by chris.baglieri

  First time rocking it with NHibernate/Fluent so apologies in advance if this is a naive question. I have a set of Models I want to map. When I create my session factory I'm trying to do all mappings at once. I am not using auto-mapping (though I may if what I am trying to do ends up being more painful than it ought to be). The problem I am running into is that it seems only the top map is taking. Given the code snippet below and running a unit test that attempts to save 'bar', it fails and checking the logs I see NHibernate is trying to save a bar entity to the foo table. While I suspect it's my mappings it could be something else that I am simply overlooking. Code that creates the session factory (note I've also tried separate calls into .Mappings): Fluently.Configure().Database(MsSqlConfiguration.MsSql2008 .ConnectionString(c => c .Server(@"localhost\SQLEXPRESS") .Database("foo") .Username("foo") .Password("foo"))) .Mappings(m => { m.FluentMappings.AddFromAssemblyOf<FooMap>() .Conventions.Add(FluentNHibernate.Conventions.Helpers .Table.Is(x => "foos")); m.FluentMappings.AddFromAssemblyOf<BarMap>() .Conventions.Add(FluentNHibernate.Conventions.Helpers .Table.Is(x => "bars")); }) .BuildSessionFactory(); Unit test snippet: using (var session = Data.SessionHelper.SessionFactory.OpenSession()) { var bar = new Bar(); session.Save(bar); Assert.NotNull(bar.Id); }

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• std::ifstream buffer caching

  - by ledokol

  Hello everybody, In my application I'm trying to merge sorted files (keeping them sorted of course), so I have to iterate through each element in both files to write the minimal to the third one. This works pretty much slow on big files, as far as I don't see any other choice (the iteration has to be done) I'm trying to optimize file loading. I can use some amount of RAM, which I can use for buffering. I mean instead of reading 4 bytes from both files every time I can read once something like 100Mb and work with that buffer after that, until there will be no element in buffer, then I'll refill the buffer again. But I guess ifstream is already doing that, will it give me more performance and is there any reason? If fstream does, maybe I can change size of that buffer? added My current code looks like that (pseudocode) // this is done in loop int i1 = input1.read_integer(); int i2 = input2.read_integer(); if (!input1.eof() && !input2.eof()) { if (i1 < i2) { output.write(i1); input2.seek_back(sizeof(int)); } else input1.seek_back(sizeof(int)); output.write(i2); } } else { if (input1.eof()) output.write(i2); else if (input2.eof()) output.write(i1); } What I don't like here is seek_back - I have to seek back to previous position as there is no way to peek 4 bytes too much reading from file if one of the streams is in EOF it still continues to check that stream instead of putting contents of another stream directly to output, but this is not a big issue, because chunk sizes are almost always equal. Can you suggest improvement for that? Thanks.

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• using asp.net membership provider in a dll

  - by Keith Barrows

  I've used Membership Providers in web apps over the last several years. I now have a new "request" for an internal project at work. They would like a service (not a web service) to do a quick authenticate against. Basically, exposing the ValidateUser(UserName, Password) method... I am building this in a DLL that will sit with our internal web site. What is the best approach to make this work? The DLL will not reference the web app and the web app will reference the DLL. How do I make the DLL aware of the Membership Provider? TIA PS: If this has been answered elsewhere please direct me to that... EDIT: I found an article on using ASP.NET Membership with WinForms and/or WPF applications. Unfortunately, these depend on an app.config file. A DLL appears to not use the app.config once published. If I am wrong, please set me straight! The article is here: http://aspalliance.com/1595_Client_Application_Services__Part_1.all

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• Optimize INSERT / UPDATE / DELETE operation

  - by clime

  I wonder if the following script can be optimized somehow. It does write a lot to disk because it deletes possibly up-to-date rows and reinserts them. I was thinking about applying something like "insert ... on duplicate key update" and found some possibilities for single-row updates but I don't know how to apply it in the context of INSERT INTO ... SELECT query. CREATE OR REPLACE FUNCTION update_member_search_index() RETURNS VOID AS $$ DECLARE member_content_type_id INTEGER; BEGIN member_content_type_id := (SELECT id FROM django_content_type WHERE app_label='web' AND model='member'); DELETE FROM watson_searchentry WHERE content_type_id = member_content_type_id; INSERT INTO watson_searchentry (engine_slug, content_type_id, object_id, object_id_int, title, description, content, url, meta_encoded) SELECT 'default', member_content_type_id, web_member.id, web_member.id, web_member.name, '', web_user.email||' '||web_member.normalized_name||' '||web_country.name, '', '{}' FROM web_member INNER JOIN web_user ON (web_member.user_id = web_user.id) INNER JOIN web_country ON (web_member.country_id = web_country.id) WHERE web_user.is_active=TRUE; END; $$ LANGUAGE plpgsql; EDIT: Schemas of web_member, watson_searchentry, web_user, web_country: http://pastebin.com/3tRVPPVi. (content_type_id, object_id_int) in watson_searchentry is unique pair in the table but atm the index is not present (there is no use for it). This script should be run at most once a day for full rebuilds of search index.

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• Calling NSFetchedResultsController & CoreData experts

  - by JK

  I am having a few nagging issues with NSFetchedResultsController and CoreData, any of which I would be very grateful to get help on. Issue 1 - Updates: I update my store on a background thread which results in certain rows being delete, inserted or updated. The changes are merged into the context on the main thread using the "mergeChangesFromContextDidSaveNotification:" method. Inserts and deletes are updated properly, but updates are not (e.g. the cell label is not updated with the change) although I have confirmed the updates to come through the contextDidSaveNotifcation, exactly like the inserts and deleted. My current workaround is to temporarily change the staleness interval of the context to 0, but this does not seem like the ideal solution. Issue 2 - Deleting objects: My fetch batch size is 20. If an object is deleted by the background thread which is in the first 20 rows, everything works fine. But if the object is after the first 20 rows and the table is scrolled down, a "CoreData could not fulfill a fault" error is raised. I have tried resaving the context and reperforming the frc fetch - all to no avail. Note: In this scenario, the frc delegate method "didChangeObject...." is not called for the delete - I assume this is because the object in question had not been faulted at that time (as it is was outside the initial fetch range). But for some reason, the context still thinks the object is around, although is has been deleted from the store. Issue 3 - Deleting sections : When the deletion of a row leads to the deletion of a section, I have gotten the "invalid number of rows in section???" error. I have worked around this by removing the "reloadSection" line from the NSFetchedResultsChangeMove: section and replacing it with "[tableView insertRowsAtIndexPaths...." This seems to work, but once again, I am not sure if this is the best solution. Any help would be greatly appreciated. Thank you!

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• is it possible to make one click fires two events or more by javascript?

  - by NewInAlbert

  I am currently making a temporary download page for website visitor. The page includes a form, after the visitor fills the form up, the site will take them to the pdf download page. In the download page, there are some pdf files download links (I am just using a tag.). However, i wanna make a onclick event to those links, once they have been clicked, the page will refresh automatically or redirect to other pages. <a href="/file.pdf" onClick="window.location.reload()">The File</a> I have tried the jquery way as well. <a href="/file.pdf" id="FileDownload">The File</a> <script> $("#FileDownload").click(function(){ location.reload(); }); </script> But all the them are not working. Do you masters have any good ideas about this, many thanks. P.S. What if I wanna add a countdown after a file is being started download, and then do page reload when countdown finishes. Looks like have asked several questions... Thanks a ton in advance.

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• Android: Associating Browser to File Type in App

  - by tekmunki

  I'm attempting to write a simple app that associates a file type to the browser; this is assuming the browser will open the file locally... If this doesn't work, the local file - editor will be fine. I have an option of auto-mailing .ELC files from a custom app, they are basically html formatted TEXT or TXT only files; I would like to associate the .elc extension so that it will open direct from mail rather than just "Save to SD Card" as a mail option. Here's the code I'm at right now; AndroidManifest.xml: ELCViewer.java: package com.tekmunki.ELCViewer; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; public class ELCViewer extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); TextView tv = new TextView(this); tv.setText("ELC Viewer Installed! Now, when you receive the ELC files, they will open in the browser."); setContentView(tv); } } 1) How do I make the browser associated with the ELCViewer Activity? (Do I need to make a second activity, or can that all be done in the manifest?) 2) How do I make it persist after the app has been ran once?

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• Two Objects created with the same Address in Flex

  - by James

  Hi, I have an issue in flex which is causing a bit of a headache! I am adding objects to an ArrayCollection but in doing so, another ArrayCollection is also picking up these changes even though there is no binding occurring. I can see from the debug that the two ACs have the same address but for the life of me can't figure out why. I have two Array Collections: model.index.rows //The main array collection model.index.holdRows //The array collection that imitates the above This phantom data binding occurs only for the first iteration in the loop and for all others it will just write it the once. The reason this is proving troublesome is that it creates duplicate entries in my datagrid. public override function handleMessage(message:IMessage):void { super.handleMessage(message); if (message is IndexResponse) { var response:IndexResponse = message as IndexResponse; model.index.rows.removeAll(); model.index.indexIsEmpty = response.nullIndex; if (model.index.indexIsEmpty !== true) { //Update the index model from the response. Note: each property of the row object will be shown in the UI as a column in the grid response.index.forEach(function(entry:EntryData, i:int, a:Array):void { var row:Object = { fileID: entry.fileID, dadName: entry.dadName }; entry.tags.forEach(function(tag:Tag, i:int, a:Array):void { row[tag.name] = tag.value; }); model.index.rows.addItem(row); }); if(model.index.indexForNetworkView == true){ model.index.holdRows.source = model.index.holdRows.source.concat(model.index.rows.source); model.index.indexCounter++; model.index.indexForNetworkView = false; controller.indexController.showNetwork(model.index.indexCounter); } model.index.rows.refresh(); controller.networkController.show(); } } Has anyone else who has encountered something simillar propose a solution?

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• Localisable Resources: how can (should one?!) wrap a UI layer source as a BL layer service?

  - by Ciel

  A service that returns localised strings could be wrapped in a service, so that it could be used both locally (eg in an MVC app) and remotely (eg possibly Silverlight). But...if sticking with the standard practice of creating resources in the UI assembly, that would in effect make a lower layer (BL/Services) have to have a ref on a higher layer (UI)...a definite no-no. And whereas a lot of AppWide resources (eg: AppName, OK, Cancel, etc.) could be defined in a Common cross-cutting assembly, and the BL/ResourceSerouce could ref and wrap those, that doesn't work in a a Modular App, where the Core app should have no binding to/knowledge of any Module. One solution could be to have each module, once mounted in mem, 'register' their Resource files with the service, who would then return it to the service (rather a long round trip, but at least consistent as a service, and potentially resources/images could be shared with other resources). Secondly, that may work in a web app...but not sure how that pattern could be extended to a Silverlight modular app (the round tripping becomes prohibitive). ie...what are best practices for allowing Resources to be to be defined by the UI designer, in a higher level, but served from the lower BL layer, as a Service? Or is there a better way of understanding/solving the problem?

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• How do I avoid a race condition in my Rails app?

  - by Cathal

  Hi, I have a really simple Rails application that allows users to register their attendance on a set of courses. The ActiveRecord models are as follows: class Course < ActiveRecord::Base has_many :scheduled_runs ... end class ScheduledRun < ActiveRecord::Base belongs_to :course has_many :attendances has_many :attendees, :through => :attendances ... end class Attendance < ActiveRecord::Base belongs_to :user belongs_to :scheduled_run, :counter_cache => true ... end class User < ActiveRecord::Base has_many :attendances has_many :registered_courses, :through => :attendances, :source => :scheduled_run end A ScheduledRun instance has a finite number of places available, and once the limit is reached, no more attendances can be accepted. def full? attendances_count == capacity end attendances_count is a counter cache column holding the number of attendance associations created for a particular ScheduledRun record. My problem is that I don't fully know the correct way to ensure that a race condition doesn't occur when 1 or more people attempt to register for the last available place on a course at the same time. My Attendance controller looks like this: class AttendancesController < ApplicationController before_filter :load_scheduled_run before_filter :load_user, :only => :create def new @user = User.new end def create unless @user.valid? render :action => 'new' end @attendance = @user.attendances.build(:scheduled_run_id => params[:scheduled_run_id]) if @attendance.save flash[:notice] = "Successfully created attendance." redirect_to root_url else render :action => 'new' end end protected def load_scheduled_run @run = ScheduledRun.find(params[:scheduled_run_id]) end def load_user @user = User.create_new_or_load_existing(params[:user]) end end As you can see, it doesn't take into account where the ScheduledRun instance has already reached capacity. Any help on this would be greatly appreciated.

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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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• The best way to write a jQuery plugin - If there is such a way?

  - by Nick Lowman

  There are quite a few ways to write plugins i.e. here's a nice example and what I've seen quite a lot of lately is the following code pattern and it's used by Doug Neiner here; (function($){ $.formatLink = function(el, options){ var base = this; base.$el = $(el); base.el = el; base.$el.data("formatLink", base); base.init = function(){ base.options = $.extend({}, $.formatLink.defaultOptions, options); //code here } base.init(); }; $.formatLink.defaultOptions = { }; $.fn.formatLink = function(options){ return this.each(function(){ (new $.formatLink(this, options)); }); }; })(jQuery); So, can anyone tell me the benefits of using the pattern above rather than the one below. I can't see the point in calling the $.extend function for every element in the jQuery stack (above), where the example below only does this once and then works on the stack. To test it I created two plugins, using both patterns, which applied styles to about 5000 li elements and the code below took about 1 second whereas the pattern above took about 1.3 seconds. (function($){ $.fn.formatLink = function(options){ var options = $.extend({}, $.fn.formatLink.defaultOptions, options || {}); return this.each(function(){ //code here }); }); $.fn.formatLink.defaultOptions ={} })(jQuery);

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• Use of properties vs backing-field inside owner class

  - by whatispunk

  I love auto-implemented properties in C# but lately there's been this elephant standing in my cubicle and I don't know what to do with him. If I use auto-implemented properties (hereafter "aip") then I no longer have a private backing field to use internally. This is fine because the aip has no side-effects. But what if later on I need to add some extra processing in the get or set? Now I need to create a backing-field so I can expand my getters and setters. This is fine for external code using the class, because they won't notice the difference. But now all of the internal references to the aip are going to invoke these side-effects when they access the property. Now all internal access to the once aip must be refactored to use the backing-field. So my question is, what do most of you do? Do you use auto-implemented properties or do you prefer to always use a backing-field? What do you think about properties with side-effects?

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• How do I save the edits for a checkbox that implements an email notification?

  - by Ralph The Mouf

  On my site, a user gets email notifications when someone comments on their profile, or comments on their blog etc...I have made a email settings page that has checkboxes to allow the user to decide to receive emails or not. This is what I am wrapping around the email notification code chunck for the pages that have the php mail: <?php if(isset($_POST['email_toggle']) && $_POST['email_toggle'] == 'true') { if(isset($_POST['commentProfileSubmit']) && $auth) { $query etc $to = etc } } My question is what do I put on the email settings script that has the actual check boxes to make them stay checked or unchecked once you submit your settings? Another words what do I put in the if(isset portion to implement the changes? if(isset($_POST['email_toggle']) && $_POST['email_toggle'] == 'true') { /* what do I put here? */ header("Location: Profile.php?id=" . $auth->id); mysql_query($query,$connection); /* input/check boxes and submit button */ <tr> <td class="email_check"> <input type="checkbox" name="email_toggle" value="true" checked="checked" /> Receive email Notifications When Someone Answers A Question You've Answered </td> </tr> <tr> <td> <input style="margin:10px 0px 0px 10px;" class="submit" type="submit" name="email_toggle" value="Save Settings" /> </td> </tr> }

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• My list item's child label elements disappear in IE on accordion menu opening

  - by Scott B

  I've got an app that's working pretty flawlessly in Chrome and FF, however, when I view it in IE, all is well until I click on a header element to activate it (jQuery accordion). What happens then is that I see a brief flash where the content is there, then suddenly the entire left column disappears. This column is generated by a floated label element with a class of ".left" as seen below... <ul class="menu collapsible"> <li class='expand sectionTitle'><a href='#'>General Settings</a> <ul class='acitem'> <li class="section"> <label class="left">This item if floated left with a defined width of 190px via css. This is the item that's disappearing after a brief display</label> <input class="input" value="input element here" /> <label class="description">This element has a margin-left:212px; set via css in order to be positioned to the right of the label element as if in an adjacent table cell. When I add a max-width property to this element, it disappears in IE too!</label> </li> </ul> </li> </ul> As you can see from the comments in the code above (for the two label elements) the description label disappears once I set a max-width on it (I don't have a max-width on the left label element, but it disappears nonetheless). The initial view of this UL menu is fine (note the expand class declaration which makes this part of the accordion open at startup. Its not until I click the "General Settings" to toggle it closed, then back open, that the left class elements disappear (and only in IE)

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