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• Should I store generated code in source control

  - by Ron Harlev

  This is a debate I'm taking a part in. I would like to get more opinions and points of view. We have some classes that are generated in build time to handle DB operations (in This specific case, with SubSonic, but I don't think it is very important for the question). The generation is set as a pre-build step in Visual Studio. So every time a developer (or the official build process) runs a build, these classes are generated, and then compiled into the project. Now some people are claiming, that having these classes saved in source control could cause confusion, in case the code you get, doesn't match what would have been generated in your own environment. I would like to have a way to trace back the history of the code, even if it is usually treated as a black box. Any arguments or counter arguments? UPDATE: I asked this question since I really believed there is one definitive answer. Looking at all the responses, I could say with high level of certainty, that there is no such answer. The decision should be made based on more than one parameter. Reading the answers below could provide a very good guideline to the types of questions you should be asking yourself when having to decide on this issue. I won't select an accepted answer at this point for the reasons mentioned above.

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• dynamically horizontal scalable key value store

  - by Zubair

  Hi, Is there a key value store that will give me the following: Allow me to simply add and remove nodes and will redstribute the data automatically Allow me to remove nodes and still have 2 extra data nodes to provide redundancy Allow me to store text or images up to 1GB in size Can store small size data up to 100TB of data Fast (so will allow queries to be performed on top of it) Make all this transparent to the client Works on Ubuntu/FreeBSD or Mac Free or open source I basically want something I can use a "single", and not have to worry about having memcached, a db, and several storage components so yes, I do want a database "silver bullet" you could say. Thanks Zubair Answers so far: MogileFS on top of BackBlaze - As far as I can see this is just a filesystem, and after some research it only seems to be appropriate for large image files Tokyo Tyrant - Needs lightcloud. This doesn't auto scale as you add new nodes. I did look into this and it seems it is very fast for queries which fit onto a single node though Riak - This is one I am looking into myself, but I don't have any results yet Amazon S3 - Is anyone using this as their sole persistance layer in production? From what I have seen it seems to be used for storage of images as complex queries are too expensive @shaman suggested Cassandra - definitely one I am looking into So far it seems that there is no database or key value store that fulfills the criteria I mentioned, not even after offering a bounty of 100 points did the question get answered!

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• 3n+1 problem at UVa

  - by ShahradR

  Hello, I am having trouble with the first question in the Programming Challenges book by Skiena and Revilla. I keep getting a "Wrong Answer" error message, and I don't know why. I've ran my code against the sample input, and I keep getting the right answer. Anyways, if anyone could help me, I would really appreciate it :) Here is the problem URL: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=29&page=show_problem&problem=36 And here is the code:` import java.util.Scanner; public class Main { static Scanner kb = new Scanner(System.in); public static void main(String[] args) { while (kb.hasNext()) { long[] numericalInput = {0, 0}; long i = kb.nextLong(); long j = kb.nextLong(); if (i > j) { numericalInput[0] = i; numericalInput[1] = j; } else { numericalInput[0] = j; numericalInput[1] = i; } long maxIterations = 0; for (long n = numericalInput[0]; n <= numericalInput[1]; n += 1) { if (maxIterations < returnIterations(n)) maxIterations = returnIterations(n); } System.out.println(i + " " + j + " " + maxIterations); } System.exit(0); } public static long returnIterations(long num) { long iterations = 0; while (num != 1) { if (num % 2 == 0) num = num / 2; else num = 3 * num + 1; iterations += 1; } iterations += 1; return iterations; } } ` EDIT: I think the problem is with the output. I tried to make it accept all the input first and then display all the answers at once, but I didn't know the terminating condition. I resorted to this method, but I'm not sure that's what the judge wants...

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• How can I attach a file using Wordpress custom fields / meta boxes?

  - by shipshape

  I am using Wordpress's add_meta_box() function to add customized meta fields to the Add New Post page, like this. I want one of these fields to allow the user to upload a file, so that a single image, pdf, audio file, or video can be associated with the post. The closest example I've seen is this one. Unfortunately it does not suit my needs, as I want my file to be processed by Wordpress's Media Uploader - so it should appear in the Media Library afterwards, and thumbnails should be generated according to the Media settings. I think ideally there would be a way to tap into Wordpress's existing Add Media dialog, and simply output the URL of the uploaded file into a text box, but I don't see how to do that. This question is similar, but the answers are a little clunky - I would like to keep this super simple for my end users. How can I accomplish this? Please do not recommend plugins such as Flutter or Magic Fields - I have tried these and they do not suit my purposes (I want the images to be processed by Wordpress's Media Uploader). I am using Wordpress 3.0-alpha. Thanks!

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• Rails : fighting long http response times with ajax. Is it a good idea? Please, help with implementa

  - by baranov

  Hi, everybody! I've googled some tutorials, browsed some SO answers, and was unable to find a recipe for my problem. I'm writing a web site which is supposed to display almost realtime stock chart. Data is stored in constantly updating MySQL database, I wrote a find_by_sql query code which fetches all the data I need to get my chart drawn. Everything is ok, except performance - it takes from one second to one minute for different queries to fetch all the data from the database, this time includes necessary (My)SQL-server side calculations. This is simply unacceptable. I got the following idea: if the data is queried from the MySQL server one point a time instead of entire dataset, it takes only about 1-100ms to get an individual point. I imagine the data fetch process might be browser-driven. After the user presses the button in order to get a chart drawn, controller makes one request to the database and renders, say, a progress bar, say 1% ready. When the browser gets the response, it immediately makes an (ajax) request, and the server fetches the next piece of data and renders "2%". And so on, until all the data is ready and the server displays the requested chart. Could this be implemented in rails+js, is there a tutorial for solving a similar problem on the Web? I suppose if the thing is feasible at all, somebody should have already done this before. I have read several articles about ajax, I believe I do understand general principles, but never did nontrivial ajax programming myself. Thanks for your time!

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• How can I stop an auto-generated Linq to SQL class from loading ALL data?

  - by Gary McGill

  DUPLICATE of http://stackoverflow.com/questions/2433422/how-can-i-stop-an-auto-generated-linq-to-sql-class-from-loading-all-data post answers there! I have an ASP.NET MVC project, much like the NerdDinner tutorial example. (I'm using MVC 2, but followed the NerdDinner tutorial in order to create it). As per the instructions in part 3 of the tutorial, I've created a Linq-to-SQL model of my database by creating a "Linq to SQL Classes" (.dbml) surface, and dropping my database tables onto it. The designer has automatically added relationships between the generated classes based on my database tables. Let's say that my classes are as per the NerdDinner example, so I have Dinner and RSVP tables, where each Dinner record is associated with many RSVP records - hence in the generated classes, the Dinner object has a RSVPs property which is a list of RSVP objects. My problem is this: it appears (and I'd be gladly proved wrong on this) that as soon as I access a Dinner object, it's loading all of the corresponding RSVP objects, even if I don't use the RSVPs member. First question: is this really the default behavior for the generated classes? In my particular situation, the object graph contains many more tables (which have an order of magnitude more records), and so this is disastrous behaviour - I'd be loading tons of data when all I want to do is show the details of a single parent record. Second question: are there any properties exposed through the designer UI that would let me modify this behavior? (I can't find any). Third question: I've seen a description of how to control the loading of related records in a DataContext by using a DataShape object associated with the DataContext. Is that what I'm meant to do, and if so are there any tutorials like the NerdDinner one that would show not only how to do it, but also suggest a 'pattern' for normal use?

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• jQuery eval of ajax inline script not throwing errors

  - by Josh

  http://stackoverflow.com/questions/606794/debugging-ajax-code-with-firebug This question is quite similar, though old and without real answers. I'm currently putting together an app that has scripts that get loaded in with an ajax request. An example: var main = _main.get(); main.load( someurl ); Where someurl is a page that contains an inline script element: <script type="text/javascript"> $(document).ready( function(){ var activities = new activities(); activities.init(); }); </script> jQuery will do a line by line eval of js that lives in inline script tags. The problem is, I get no errors or any information whatsoever in firebug when something goes awry. Does anyone have a good solution for this? Or a better practice for loading pages which contain javascript functionality? Edit: A little progress... so at the top of the page that is being loaded in via ajax, I have another script that was being included like this: <script type="text/javascript" src="javascript/pages/activities.js"></script> When I moved the inline $(document).ready() code in the page to the end of this included file, instead, syntax errors were now properly getting thrown. As an aside, I threw a console.log() into the inline script tag, and it was being logged just fine. I also tried removing the $(document).ready() altogether, and also switching it out for a $(window).load() event. No difference. May have something to do with the inline scripts dependency on the included activities.js, I guess. :: shakes head :: javascript can be a nightmare.

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• Java: Cleaning up what causes a connection reset

  - by Zombies

  There seems to be some confusion as well contradicting statements on various SO answers: http://stackoverflow.com/questions/585599/whats-causing-my-java-net-socketexception-connection-reset . You can see here that the accepted answer states that the connection was closed by other side. But this is not true, closing a connection doesn't cause a connection reset. It is cauesed by "an underlying TCP/IP error." What I want to know is if a SocketException: Connection reset means really besides "unerlying TCP/IP Error." What really causes this? As I doubt it has anything to do with the connection being closed (since closing a connection isn't an exception worthy flag, and reading from a closed connection is, but that isn't an "underlying TCP/IP error." My hypothesis is this Connection reset is caused from a server's failure to acknowledge an ACK packet (either wholly or just improperly as per TCP/IP). And that a SocketTimeoutException is generated only when no data is generated to be read (since this is thrown during a read after a certain duration, and read is waiting for data, but is not concerned with ACK packets). In other words, read() throws SocketTimeoutException if it didn't read any bytes of actual data (DATA LAYER) in its allotted time.

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• Query optimization (OR based)

  - by john194

  I have googled but I can't find answers for these questions. Your advice is appreciated. centOS on vps with 512MB RAM, nginx, php5 (fastcgi), mysql5 (myisam, not innodb). I need to optimize this app created by some ex-employee. This app is working, but it's slow. Table: t1(id[bigint(20)],c1[mediumtext],c2[mediumtext],c3[mediumtext],c4[mediumtext]) id is some random big number, and is PK Those mediumtext rows look like this: c1="|box-002877|" c2="|ct-2348|rd-11124854|hw-3949|wd-8872|hw-119037736|...etc.. " c3="|fg-2448|wd-11172|hw-1656|...etc.. " c4="|hg-2448|qd-16667|...etc." (some columns contain a lot of data, around 900 KiB, database around 300 MiB) Yes, mediumtext "is bad", and (20) is too big... but I didn't create this. Those codes can be found on any of those 4 mediumtext's... //he needs all the columns of the row containing $code, so he wrote this: function f1($code) { SELECT * FROM t1 WHERE c1 LIKE '%$code%' OR c2 LIKE '%$code%' OR c3 LIKE '%$code%' OR c4 LIKE '%$code%'; Questions: Q1. If $code is found on c1... mysql automatically stops checking and returns row=id+c1+c2+c3+c4? or it will continue (wasting time) checking c2, c3 and c4?... Q2. Mysql is working with this table on disk (not RAM) because of the mediumtext, right? is this the primary cause of slowness? Q3. That query can be cached by mysql (if using a big query_cache_size=128M value on the my.cnf)? or that's not cacheable due to the mediumtexts, or due to the "OR LIKE"...? Q4. Do you recommend rewriting this with mysql's INSTR() / LOCATE() / MATCH..AGAINST [FULLTEXT]?

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• Building an extension framework for a Rails app

  - by obvio171

  I'm starting research on what I'd need in order to build a user-level plugin system (like Wordpress plugins) for a Rails app, so I'd appreciate some general pointers/advice. By user-level plugin I mean a package a user can extract into a folder and have it show up on an admin interface, allowing them to add some extra configuration and then activate it. What is the best way to go about doing this? Is there any other opensource project that does this already? What does Rails itself already offer for programmer-level plugins that could be leveraged? Any Rails plugins that could help me with this? A plugin would have to be able to: run its own migrations (with this? it's undocumented) have access to my models (plugins already do) have entry points for adding content to views (can be done with content_for and yield) replace entire views or partials (how?) provide its own admin and user-facing views (how?) create its own routes (or maybe just announce its presence and let me create the routes for it, to avoid plugins stepping on each other's toes) Anything else I'm missing? Also, is there a way to limit which tables/actions the plugin has access to concerning migrations and models, and also limit their access to routes (maybe letting them include, but not remove routes)? P.S.: I'll try to keep this updated, compiling stuff I figure out and relevant answers so as to have a sort of guide for others.

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• Data Binding to an object in C#

  - by Allen

  Objective-c/cocoa offers a form of binding where a control's properties (ie text in a textbox) can be bound to the property of an object. I am trying to duplicate this functionality in C# w/ .Net 3.5. I have created the following very simple class in the file MyClass.cs: class MyClass { private string myName; public string MyName { get { return myName; } set { myName = value; } } public MyClass() { myName = "Allen"; } } I also created a simple form with 1 textbox and 1 button. I init'd one instance of Myclass inside the form code and built the project. Using the DataSource Wizard in Vs2008, i selected to create a data source based on object, and selected the MyClass assembly. This created a datasource entity. I changed the databinding of the textbox to this datasource; however, the expected result (that the textbox's contents would be "allen") was not achieved. Further, putting text into the textbox is not updating the name property of the object. I know i'm missing something fundamental here. At some point i should have to tie my instance of the MyClass class that i initialized inside the form code to the textbox, but that hasn't occurred. Everything i've looked at online seems to gloss over using DataBinding with an object (or i'm missing the mark entirely), so any help is great appreciated. ----Edit--- Utilizing what i learned by the answers, i looked at the code generated by Visual Studio, it had the following: this.myClassBindingSource.DataSource = typeof(BindingTest.MyClass); if i comment that out and substitute : this.myClassBindingSource.DataSource = new MyClass(); i get the expected behavior. Why is the default code generated by VS like it is? Assuming this is more correct than the method that works, how should i modify my code to work within the bounds of what VS generated?

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• C#/.Net Error: MySql.Data Object reference not set to an instance of an object.

  - by Simon

  Hello, I get this exception on my Windows 7 64bit in application running in VS 2008 express. I am using Connector/Net 6.2.2.0: Message: Object reference not set to an instance of an object. Source: MySql.Data in MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int32& insertedId) Stack trace: in MySql.Data.MySqlClient.Driver.GetResult(Int32 statementId, Int32& affectedRows, Int32& insertedId) in MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId) in MySql.Data.MySqlClient.MySqlDataReader.NextResult() in MySql.Data.MySqlClient.MySqlDataReader.Close() in MySql.Data.MySqlClient.MySqlConnection.Close() in MySql.Data.MySqlClient.MySqlConnection.Dispose(Boolean disposing) in System.ComponentModel.Component.Finalize() No inner exception. This exception is unhalted and the debugger dont point on any code line. It just say "Object reference not set to an instance of an object. MySql.Data" This error is really hard to repeat. On my Windows XP 32bit is all ok. Could it be error in 64bit Windows 7? Thank you very much for your answers. Regards, simon

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• Ember model is gone when I use the renderTemplate hook

  - by Mickael Caruso

  I have a single template - editPerson.hbs <form role="form"> FirstName: {{input type="text" value=model.firstName }} <br/> LastName: {{input type="text" value=model.lastName }} </form> I want to render this template when the user wants to edit an existing person or create a new person. So, I set up routes: App.Router.map(function(){ this.route("createPerson", { path: "/person/new" }); this.route("editPerson", { path: "/person/:id}); // other routes not show for brevity }); So, I define two routes - one for create and one for edit: App.CreatePersonRoute = Ember.Route.extend({ renderTemplate: function(){ this.render("editPerson", { controller: "editPerson" }); }, model: function(){ return {firstName: "John", lastName: "Smith" }; } }); App.EditPersonRoute = Ember.Route.extend({ model: function(id){ return {firstName: "John Existing", lastName: "Smith Existing" }; } }); So, I hard-code the models. I'm concerned about the createPerson route. I'm telling it to render the editPersonTemplate and to use the editPerson controller (which I don't show because I don't think it matters - but I made one, though.) When I use renderTemplate, I lose the model John Smith, which in turn, won't display on the editTemplate on the web page. Why? I "fixed" this by creating a separate and identical (to editPerson.hbs) createPerson.hbs, and removing the renderTemplate hook in the CreatePerson. It works as expected, but I find it somewhat troubling to have a separate and identical template for the edit and create cases. I looked everywhere for how to properly do this, and I found no answers.

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• Qmake does not specify a valid qt

  - by Comptrol

  After installing Qt SDK for Open Source C++ development on Mac OS by following the respective steps Note for the binary package: If you have the binary package, simply double-click on the Qt.mpkg and follow the instructions to install Qt. . Yes, that is all I have done to install Qt on MacOsX. Everything was going fine, until I run a sample application, of which compile output resulted in: No valid Qt version set. Set one in Preferences Error while building project qtilk When executing build step 'QMake' Canceled build. Then I tried to change the respective Qt version in Preferences and I hovered over the Path, I realized my mkspec isn't set: Then I tried querying qmake by qmake -query : QT_INSTALL_PREFIX:/ QT_INSTALL_DATA:/usr/local/Qt4.6 QT_INSTALL_DOCS:/Developer/Documentation/Qt QT_INSTALL_HEADERS:/usr/include QT_INSTALL_LIBS:/Library/Frameworks QT_INSTALL_BINS:/Developer/Tools/Qt QT_INSTALL_PLUGINS:/Developer/Applications/Qt/plugins QT_INSTALL_TRANSLATIONS:/Developer/Applications/Qt/translations QT_INSTALL_CONFIGURATION:/Library/Preferences/Qt QT_INSTALL_EXAMPLES:/Developer/Examples/Qt/ QT_INSTALL_DEMOS:/Developer/Examples/Qt/Demos QMAKE_MKSPECS:/usr/local/Qt4.6/mkspecs QMAKE_VERSION:2.01a QT_VERSION:4.6.2 QMAKE_MKSPECS seems to be set here?? Will setting my mkspec solve my building problem? I tried setting by typing export mkspec=macx-g++. Still, mkspec seems not to be set to anything. I am all ears waiting for your answers. Thanks in advance.

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• What specific features of LabView are frustrating to you?

  - by Underflow

  Please bear with me: this isn't a language debate or a flame. It's a real request for opinions. Occasionally, I have to help educate a traditional text coder in how to think in LabVIEW (LV). Often during this process, I get to hear about how LV sucks. Rarely is this insight accompanied by rational observations other than "Language X is just so much better!". While this statement is satisfying to them, it doesn't help me understand what is frustrating them. So, for those of you with LabVIEW and text language experience, what specific things about LV drive you nuts? ------ Summaries ------- Thanks for all the answers! Some of the issues are answered in the comments below, some exist on other sites, and some are just genuine problems with LV. In the spirit of the original question, I'm not going to try to answer all of these here: check LAVA or NI's website, and you'll be pleasantly surprised at how many of these things can be overcome. Unintentional concurrency No access to tradition text manipulation tools Binary-only source code control Difficult to branch and merge Too many open windows Text has cleaner/clearer/more expressive syntax Clean coding requires a lot of time and manipulation Large, difficult to access API/palette system Mouse required File namespacing: no duplicate files with the same name in memory LV objects are natively by-value only Requires dev environment to view code Lack of zoom Slow startup Memory pig "Giant" code is difficult to work with UI lockup is easy to do Trackpads and LV don't mix well String manipulation is graphically bloated Limited UI customization "Hidden" primitives (yes, these exist) Lack of official metaprogramming capability (not for much longer, though) Lack of unicode support [1]: http://www.lavag.org LAVA

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• Event OnClick ASP:LinkButton not firing with jquery overlay

  - by rolando

  Hi there, So i have this: <asp:LinkButton runat="server" id="lkbTomeChichi" class="modalInput contratacionVinculos" rel="#prueba" OnClick="PruebaBrava" >LinkPrueba</asp:LinkButton> <div id="prueba" class="simple_overlayFondoBlanco" style="margin: auto; z-index: 99;"> hola como está todo ;) </div> and i have this: <script type="text/javascript"> function pageLoad() { var triggers = $("a.modalInput").overlay({ // some expose tweaks suitable for modal dialogs expose: { color: '#333', loadSpeed: 200, opacity: 0.3, zIndex: 99 }, top: '25%', closeOnClick: true }); } </script> as you can see i'm using a LinkButton who transforms into an 'a' tag on rendering so jquery pageLoad function can use it to show an overlay. My problem is i need the 'OnClick="PruebaBrava' to execute before the overlay shows. If i use a button instead of a LinkButton it works perfectly but i need to use the linkbutton and with it that event is not firing. What can i do? Thankyou all very much for your answers ;)

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• process of connecting RTP with SIP via SDP & land lines

  - by TacB0sS

  Hello to everyone, I have a problem with starting a media session and to combine it with my SIP client. I've designed a recursive SIP client that reuse the same request template to send the next requests to server, according to the acceptable sequences noted in the RFC's, and examples that I read. as far as I could tell the SIP part is working fine registers to server invites, and authenticates. I didn't complete any calls to clients yet because of the content header needs to be filled up (which I didn't yet so I get a 503 from the server which is OK I guess). for a long time I didn't know where to start with the media session, and slowly learned how to use the JMF and I've constructed an object that handles RTP transmitting, now I'm standing at the cross road, on the one hand I have my SIP signaling but it needs the SDP content header to complete the invite, and on the other I have the RTP which is knows how to p2p. For me to complete my design I require your help with the following questions: Is there an easy//a simple//an implemented way to convert the Audio/Video format from the JMF into SDP media headers? or even a generator that I would input all the parameters for the content header, and it would generate a content header fast, or do I have to implement this myself? Once I've finished constructing the SDK and the SIP is up and running and I get an OK response from the server (after ringing and all), how do I start the media session? do I connect p2p according to caller details I send in the SIP invite? If 2 is correct, then how does a connection to land lines would be? does land lines knows that once they send an OK back to server they listen/start RTP session on a specific port? Or did I get everything wrong? :-/ I really appreciate any help I could I get, I looked every where for answers but they are not clear, they ignore question 2 as if it was an obvious thing, but for me it just isn't. Thank in advance, Adam Zehavi.

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• Python script, runs well, but not perfectly, debugging help.

  - by S1syphus

  What it does (sort of)... or is meant to, the script reads from a csv file that contains information on sound files and create a play list exactly 60 minutes long. An example csv, contains: their title, duration (in seconds), minium total time to be played (in minutes) An example is: Soundfoo,120,10 Soundbar,30,6 Sounddev,60,20 Soundrandom,15,8 The script works out the minimum instances of plays, take 'Soundfoo' for example, the length of each sample is 120 seconds and the minimum time to be played is 10 minutes, so basic maths 10*60/120 gives the number of instances the song is to be played, in this case 5. It is meant to take minimum number of instances and spread out equally from each other; so there will never be a period where for example Soundbar is played twice in a row. Then if the minium instances of each song has been used, and there is still time with in the 60 min, how is it possible to tell it to go back and fill the time by selecting each sound and including it till the 60 min is filled while remaining sparsely populated. Heres the issue(s)! The script fails to calculate the actual time require to play all the sounds in a file and the total time of the playlist, the thing is tho it doesn't get it wrong all the time maybe 3/5 times, even if I run it on the same csv file it will give me different answers. Here is the file I shall run the script on e for sake of ease to see the issue: Sound1,60,10 Sound2,60,10 Sound3,60,10 Sound4,60,10 Sound5,60,10 Sound6,60,10 I'll do it three times and post the results: 1 Required playtime in minutes: 60 Actual time in minutes to play all required ads: 62 Total playtime in minutes: 62.0 2 Required playtime in minutes: 60 Actual time in minutes to play all required ads: 71 Total playtime in minutes: 71.0 3 Required playtime in minutes: 60 Actual time in minutes to play all required ads: 60 Total playtime in minutes: 60.0 Relevant Code: pastebin.com/demkBXk6 And finally... in context: http://pastebin.com/demkBXk6 If you made it down to here, thanks for staying and reading, kudos.

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• Understanding evaluation of expressions containing '++' and '->' operators in C.

  - by Leif Ericson

  Consider this example: struct { int num; } s, *ps; s.num = 0; ps = &s; ++ps->num; printf("%d", s.num); /* Prints 1 */ It prints 1. So I understand that it is because according to operators precedence, -> is higher than ++, so the value ps->num (which is 0) is firstly fetched and then the ++ operator operates on it, so it increments it to 1. struct { int num; } s, *ps; s.num = 0; ps = &s; ps++->num; printf("%d", s.num); /* Prints 0 */ In this example I get 0 and I don't understand why; the explanation of the first example should be the same for this example. But it seems that this expression is evaluated as follows: At first, the operator ++ operates, and it operates on ps, so it increments it to the next struct. Only then -> operates and it does nothing because it just fetches the num field of the next struct and does nothing with it. But it contradicts the precedence of operators, which says that -> have higher precedence than ++. Can someone explain this behavior? Edit: After reading two answers which refer to a C++ precedence tables which indicate that a prefix ++/-- operators have lower precedence than ->, I did some googling and came up with this link that states that this rule applies also to C itself. It fits exactly and fully explains this behavior, but I must add that the table in this link contradicts a table in my own copy of K&R ANSI C. So if you have suggestions as to which source is correct I would like to know. Thanks.

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• Passing two variables to separate table...associations problem

  - by bgadoci

  I have developed an application and I seem to be having some problems with my associations. I have the following: class User < ActiveRecord::Base acts_as_authentic has_many :questions, :dependent => :destroy has_many :sites , :dependent => :destroy end Questions class Question < ActiveRecord::Base has_many :sites, :dependent => :destroy has_many :notes, :through => :sites belongs_to :user end Sites (think of this as answers to questions) class Site < ActiveRecord::Base acts_as_voteable :vote_counter => true belongs_to :question belongs_to :user has_many :notes, :dependent => :destroy has_many :likes, :dependent => :destroy has_attached_file :photo, :styles => { :small => "250x250>" } validates_presence_of :name, :description end When a Site (answer) is created I am successfully passing the question_id to the Sites table but I can't figure out how to also pass the user_id. Here is my SitesController#create def create @question = Question.find(params[:question_id]) @site = @question.sites.create!(params[:site]) respond_to do |format| format.html { redirect_to(@question) } format.js end end

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• Rebinding and singleton-behaviour [NInject]

  - by Maximilian Csuk

  Hi! I have set up a NInject (using version 1.5) binding like this: Bind<ISessionFactory>().ToMethod<ISessionFactory>(ctx => { try { // create session factory, might fail because of database issues like wrong connection string } catch (Exception e) { throw new DatabaseException(e); } }).Using<SingletonBehavior>(); As you can see, this binding uses a singleton behavior but can also throw exception when something is not configured correctly, like a wrong connection string to the database. Now, when the creation of a session factory fails at first (throwing a database exception), NInject doesn't try to create the object again but always returns null. I would need NInject to check for null first and recreate when the instance is null, but of course not when there already is an instance successfully constructed (keeping it singleton). Like this: var a = Kernel.Get<ISessionFactory>(); // might fail, a = null // ... change some database settings var b = Kernel.Get<ISessionFactory>(); // might not fail anymore, b = ISessionFactory object Would I need to write a custom behavior or am I missing something else? Thanks for your answers!

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• Delphi 2009 dbExpress and Interbase: Unicode migration steps and risks?

  - by mjustin

  Currently, our database uses Win1252 as the only character encoding. We will have to support Unicode in the database tables soon, which means we have to perform this migration for four databases and around 80 Delphi applications which run in-house in a 24/7 environment. Are there recommendations for database migrations to UTF-8 (or UNICODE_FSS) for Delphi applications? Some questions listed below. Many thanks in advance for your answers! are there tools which help with the migration of the existing databases (sizes between 250 MB and 2 GB, no Blob fields), by dumping the data, recreating the database with UNICODE_FSS or UTF-8, and loading the data back? are there known problems with Delphi 2009, dbExpress and Interbase 7.5 related to Unicode character sets? would you recommend to upgrade the databases to Interbase 2009 first? (This upgrade is planned but does not have a high priority) can we simply migrate the database and Delphi will handle the Unicode character sets automatically, or will we have to change all character field types in every Datamodule (dfm and source code) too? which strategy would you recommend to work on the migration in parallel with the normal development and maintenance of the existing application? The application runs in-house so development and database administration is done internally. Update: one problem I found now is that there are two different persistent field types for Unicode and non Unicode character fields. For the existing database, dbExpress creates TStringField objects. For the Unicode database fields, dbExpress creates (or expects!) TWideStringField objects. This looks like a lot of work lies ahead. While we could try to avoid persistent fields (and add calculated fields at run time), Of course we would prefer a solution which does not require so many changes in existing units and DFM files.

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• Selenium and Firefox 9's "Will you help improve Mozilla Firefox" popup

  - by Rup

  I'm trying to test a Java web app using Selenium 2.16.1. When Selenium opens Firefox, I see a band at the top of the page with message "Will you help improve Mozilla Firefox" For some reason this breaks selenium.click("id=submit"); selenium.waitForPageToLoad("60000"); which is trying to log in - it becomes a no-op, and the test fails because it's then expecting to have logged in. If I break on the click line and clear the 'will you help' band before continuing then the form submit succeeds. Is there a way to suppress this band from appearing? (I expect that would mean setting a property in Firefox's default profile - where do I find that?) Or is there a way to get Selenium to spot and dismiss this first? Thanks! I'm using Firefox 9.0.1. Solved - thanks Danny! Just in case it isn't clear from the answers and comments below: This was an issue with 2.16.1 and IMO the best solution is to upgrade to 2.17 or later.

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• Do servlet containers prevent web applications from causing each other interference and how do they do it?

  - by chrisbunney

  I know that a servlet container, such as Apache Tomcat, runs in a single instance of the JVM, which means all of its servlets will run in the same process. I also know that the architecture of the servlet container means each web application exists in its own context, which suggests it is isolated from other web applications. As depicted here: Accepting that each web application is isolated, I would expect that you could create 2 copies of an identical web application, change the names and context paths of each (as well as any other relevant configuration), and run them in parallel without one affecting the other. The answers to this question appear to support this view. However, a colleague disagrees based on their experience of attempting just that. They took a web application and tried to run 2 separate instances (with different names etc) in the same servlet container and experienced issues with the 2 instances conflicting (I'm unable to elaborate more as I wasn't involved in that work). Based on this, they argue that since the web applications run in the same process space, they can't be isolated and things such as class attributes would end up being inadvertently shared. This answer appears to suggest the same thing The two views don't seem to be compatible, so I ask you: Do servlet containers prevent web applications deployed to the same container from conflicting with each other? If yes, How do they do this? If no, Why does interference occur? and finally, Under what circumstances could separate web applications conflict and cause each other interference?, perhaps scenarios involving resources on the file system, native code, or database connections?

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• Two-way data binding of controls in a user control inside a FormView

  - by Sandor Drieënhuizen

  I'm trying to perform two-way data binding on the controls in my user control, which is hosted inside a FormView template. FormView: <asp:ObjectDataSource runat="server" ID="ObjectDataSource" TypeName="WebApplication1.Data" SelectMethod="GetItem" UpdateMethod="UpdateItem"> </asp:ObjectDataSource> <asp:FormView runat="server" ID="FormView"> <ItemTemplate> <uc:WebUserControl1 runat="server"></uc:WebUserControl1> </ItemTemplate> <EditItemTemplate> <uc:WebUserControl1 runat="server"></uc:WebUserControl1> </EditItemTemplate> </asp:FormView> User control: <%@ Control Language="C#" ... %> <asp:TextBox runat="server" ID="TitleTextBox" Text='<%# Bind("Title") %>'> </asp:TextBox> The binding works fine when the FormView is in View mode but when I switch to Edit mode, upon calling UpdateItem on the FormView, the bindings are lost. I know this because the FormView tries to call an update method on the ObjectDataSource that does not have an argument called 'Title'. I tried to solve this by implementing IBindableTemplate to load the controls that are inside my user control, directly into the templates (just like I had entered them declaratively like in the code above). However, when calling UpdateItem in edit mode, the container that gets passed into the ExtractValues method of the template, does not contain the TextBox anymore. It did in view mode! I have found some questions on SO that relate to this problem but they are rather dated and don't provide straight forward answers. How do you think I could solve this problem? It seems to be such a simple requirement but apparently it's more like opening a can of worms...

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