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• iPhone Apps, Objective C, a Graph, and Functions vs. Objects (or something like that)

  - by BillEccles

  Gentleones, I've got a UIImageView that I have in a UIView. This particular UIImageView displays a PNG of a graph. It's important for this particular view controller and another view controller to know what the graph "looks like," i.e., the function described by the PNG graph. These other view controllers need to be able to call a "function" of some sort with the X value returning the Y value. Please ignore the fact (from an outsider's perspective) that I could probably generate the graph programmatically. So my questions are: 1 - Where should I put this function? Should it go in one view controller or the other, or should it go in its own class or main or...? 2 - Should it be an object in some way? Or should it be a straight function? (In either case, where's it belong?) Pardon the apparent n00b-iness of the question. It's 'cause I'm honestly a n00b! This OOP stuff is giving my head a spin having been a procedural programmer for 30 years. (And I choose to learn it by jumping into an iPhone app. Talk about baptism by fire!) Thanks in advance,Bill

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• Bash PATH: How long is too long?

  - by ajwood

  Hi, I'm currently designing a software quarantine pattern to use on Ubuntu. I'm not sure how standard "quarantine" is in this context, so here is what I hope to accomplish... Inside a particular quarantine is all of the stuff one needs to run an application (bin, share, lib, etc.). Ideally, the quarantine has no leaks, which means it's not relying on any code outside of itself on the system. A quarantine can be defined as a set of executables (and some environment settings needed to make them run). I think it will be beneficial to separate the built packages enough such that upgrading to a newer version of the quarantine won't require rebuilding the whole thing. I'll be able to update just a few packages, and then the new quarantine can use some of old parts and some of the new parts. One issue I'm wondering about is the environment variables I'll be setting up to use a particular quarantines. Is there a hard limit on how big PATH can be? (either in number of characters, or in the number of directories it contains) Might a path be so long that it affects performance? Thanks very much, Andrew p.s. Any other wisdom that might help my design would be greatly appreciated :)

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• C++: static assert for const variables?

  - by shoosh

  Static asserts are very convenient for checking things in compile time. A simple static assert idiom looks like this: template<bool> struct StaticAssert; template<> struct StaticAssert<true> {}; #define STATIC_ASSERT(condition) do { StaticAssert<condition>(); } while(0) This is good for stuff like STATIC_ASSERT(sizeof(float) == 4) and: #define THIS_LIMIT (1000) ... STATIC_ASSERT(THIS_LIMIT > OTHER_LIMIT); But using #define is not the "C++" way of defining constants. C++ would have you use an anonymous namespace: namespace { const int THIS_LIMIT = 1000; } or even: static const int THIS_LIMIT = 1000; The trouble with this is that with a const int you can't use STATIC_ASSERT() and you must resort to a run-time check which is silly. Is there a way to properly solve this in current C++? I think I've read C++0x has some facility to do this...

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• C++ & proper TDD

  - by Kotti

  Hi! I recently tried developing a small-sized project in C# and during the whole project our team used the Test-Driven-Development (TDD) technique (xunit, moq). I really think this was awesome, because (when paired with C#) this approach allowed to relax when coding, relax when projecting and relax when refactoring. I suspect that all this TDD-stuff actually simplifies the coding process and, well, it allowed (eventually, for me) to get the same result with fewer brain cells working. Right after that I tried using TDD paired with C++ (I used Google Test and Google Mock libraries), and, I don't know why but I actually think that TDD here was a step back in terms of rapid application development. I had some moments when I had to spend huge amounts of time thinking of my tests, building proper mocks, rebuilding them and swearing at my monitor. And, well, I obviously can't ask something like "what I did wrong?" or "what was wrong in my approach?", because I don't know what to describe. But if there are any people who are used to TDD in C++ (and, probably C#) too, could you please advise me how to do this properly. Framework recommendations, architecture approaches, plain coding advices - if you are experienced in TDD & C++, please respond.

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• Java HashMap containsKey always false

  - by Dennis

  I have the funny situation, that I store a Coordinate into a HashMap<Coordinate, GUIGameField>. Now, the strange thing about it is, that I have a fragment of code, which should guard, that no coordinate should be used twice. But if I debug this code: if (mapForLevel.containsKey(coord)) { throw new IllegalStateException("This coordinate is already used!"); } else { ...do stuff... } ... the containsKey always returns false, although I stored a coordinate with a hashcode of 9731 into the map and the current coord also has the hashcode 9731. After that, the mapForLevel.entrySet() looks like: (java.util.HashMap$EntrySet) [(270,90)=gui.GUIGameField@29e357, (270,90)=gui.GUIGameField@ca470] What could I have possibly done wrong? I ran out of ideas. Thanks for any help! public class Coordinate { int xCoord; int yCoord; public Coordinate(int x, int y) { ...store params in attributes... } ...getters & setters... @Override public int hashCode() { int hash = 1; hash = hash * 41 + this.xCoord; hash = hash * 31 + this.yCoord; return hash; } }

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• Is learning C++ a good idea?

  - by chang

  The more I hear and read about C++ (e.g. this: http://lwn.net/Articles/249460/), I get the impression, that I'd waste my time learning C++. I some wrote network routing algorithm in C++ for a simulator, and it was a pain (as expected, especially coming from a perl/python/Java background ...). I'm never happy about giving up on some technology, but I would be happy, if I could limit my knowledge of C-family languages to just C, C# and Objective-C (even OS Xs Cocoa, which is huge and takes a lot of time to learn looks like joy compared to C++ ...). Do I need to consider myself dumb or unwilling, just because I'm not partial to the pain involved learning this stuff? Technologies advance and there will be options other than C++, when deciding on implementation languages, or not? And for speed: If speed were that critical, I'd go for a plain C implementation instead, or write C extensions for much more productive languages like ruby or python ... The one-line version of the above: Will C++ stay such a relevant language that every committed programmer should be familiar with it? [ edit / thank you very much for your interesting and useful answers so far .. ] [ edit / .. i am accepting the top-rated answer; thanks again for all answers! ]

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• Why doesn't my dataset.AcceptChanges update some new rows i've added? C#

  - by user280139

  I have a dataset in a datagrid with some data in it. Recently I've been asked to add some data to that dataset along with some controls to save the data from. I've added a few textboxes, 1 combobox and 3 textboxes that function as viewing of some datetimepickers that I have to use for dates. I've chosen to use textboxes in combination with datetimepicker because I also need to get and set the value NULL to the database. The problem is that when i call dataset.AcceptChanges() on that dataset that is binded using databinding to those controls it doesn't update the data that's contained in those three textboxes and the combobox. All the new stuff i've added works just fine. txtDataAcordare.DataBindings.Clear(); txtDataAcordare.DataBindings.Add("Text",dtPersonal,"d_DataAcordare"); txtDataInceput.DataBindings.Clear(); txtDataInceput.DataBindings.Add("Text", dtPersonal, "d_DataInceput"); txtDataSfarsit.DataBindings.Clear(); txtDataSfarsit.DataBindings.Add("Text", dtPersonal, "d_DataSfarsit"); this is the code i use to add the databinding. I am then using the datetime picker event CloseUp() to add the date into the textbox: txtDataAcordare.Text = dtpDataAcordare.Text; txtDataAcordare.Visible = true; txtDataAcordare.BringToFront(); After all my fields are completed i call: dtPersonal.AcceptChanges(); and these three textboxes don't get saved! Help, please! dtpDataAcordare.SendToBack();

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• Where do I attach the StoreKit delegate and observer in a Cocos2d App?

  - by Jeff B

  I have figured out how all of the StoreKit stuff works and have actually tested working code... however, I have a problem. I made my "store" layer/scene the SKProductsRequestDelegate. Is this the correct thing to do? I get the initial product info like so: SKProductsRequest *productRequest = [[SKProductsRequest alloc] initWithProductIdentifiers: productIDs]; [productRequest setDelegate: self]; [productRequest start]; The problem is that if I transition to a new scene when a request is in progress, the current layer is retained by the productRequest. This means that touches on my new scene/layer are handled by both the new layer and the old layer. I could cancel the productRequest when leaving the scene, but: I do not know if it is in progress at that point. I cannot release it because it may or may not have been released by the request delegates. There has got to be a better way to do this. I could make the delegate a class external to the current layer, but then I do not know how to easily update the layer with the product information when the handler is called.

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• Start developing a database application using Oracle + Net Beans

  - by Ranhiru

  I have thought of creating my first database application for one of my projects using Oracle and Java. I have chosen Netbeans as my development environment. I have a few questions to getting started. Please bare with me as I'm a complete beginner to Oracle + Netbeans This will be a data intensive (yet still for a college project) database application. I do not need 1000 user concurrency or any other very advanced features but basic stuff such as triggers, stored procedures etc. Will the 11g "Express" (XE) suffice for my requirements? Do i need any Java to Oracle bridge (database connectivity driver eg. ODBC etc) for Netbeans to connect to the oracle database? If yes, what are they? Does Netbeans support Oracle databases natively? Any easy to follow guide on how do i connect to the database and insert/retrieve/display data on a J2SE application? (I know that i should Google this but if there's any guide previously followed by anyone and is considered easy, it would be greatly appreciated.)

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• Access 2007 not allowing user to delete record in subform

  - by Todd McDermid

  Good day... The root of my issue is that there's no context menu allowing the user to delete a row from a form. The "delete" button on the ribbon is also disabled. In Access 2003, apparently this function was available, but since our recent "upgrade" to 2007 (file is still in MDB format) it's no longer there. Please keep in mind I'm not an Access dev, nor did I create this app - I inherited support for it. ;) Now for the details, and what I've tried. The form in question is a subform on a larger form. I've tried turning "AllowDeletes" on on both forms. I've checked the toolbar and ribbon properties on the forms to see if they loaded some custom stuff, but no. I've tried changing the "record locks" to "on edit", no joy. I examined the query to see if it was "too complicated" to permit a delete - as far as I can tell, it's a very simple two (linked) table join. Compared to another form in this app that does permit row deletes, it has a much more complicated (multi-join, built on queries) query. Is there a resource that would describe the required conditions for allowing deletes? Thanks in advance...

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• Git and cloning

  - by jriff

  Hi all! I have done an app for a client called 'A' (not really). I have found out that it is very cool and that I want to sell it to other clients also. The directory 'A' is a Git repository. I think I have a problem with cloning it. As far as I can see I need to make a copy of the dir 'A' and call it 'Generic_A'. Then delete the dir 'A' and do a "git clone Generic_A A" Then I could start changing the 'Generic_A'-repo with a generic design and all client references removed. But that is kind of the other way around. I should have started doing the generic design and then cloned the repo to change to the client specific design. Can I: make a new branch do all the changes to make the design generic create a patch that reflects the changes between the two remove the client specific branch rename the directory to 'Generic_A' clone the repo to a new dir 'A' apply the patch to get the client specific stuff back And if yes - how do I make the patch and apply it? Regards, Jacob

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• Trouble with building up a string in Clojure

  - by Aki Iskandar

  Hi gang - [this may seem like my problem is with Compojure, but it isn't - it's with Clojure] I've been pulling my hair out on this seemingly simple issue - but am getting nowhere. I am playing with Compojure (a light web framework for Clojure) and I would just like to generate a web page showing showing my list of todos that are in a PostgreSQL database. The code snippets are below (left out the database connection, query, etc - but that part isn't needed because specific issue is that the resulting HTML shows nothing between the <body> and </body> tags). As a test, I tried hard-coding the string in the call to main-layout, like this: (html (main-layout "Aki's Todos" "Haircut<br>Study Clojure<br>Answer a question on Stackoverfolw")) - and it works fine. So the real issue is that I do not believe I know how to build up a string in Clojure. Not the idiomatic way, and not by calling out to Java's StringBuilder either - as I have attempted to do in the code below. A virtual beer, and a big upvote to whoever can solve it! Many thanks! ============================================================= ;The master template (a very simple POC for now, but can expand on it later) (defn main-layout "This is one of the html layouts for the pages assets - just like a master page" [title body] (html [:html [:head [:title title] (include-js "todos.js") (include-css "todos.css")] [:body body]])) (defn show-all-todos "This function will generate the todos HTML table and call the layout function" [] (let [rs (select-all-todos) sbHTML (new StringBuilder)] (for [rec rs] (.append sbHTML (str rec "<br><br>"))) (html (main-layout "Aki's Todos" (.toString sbHTML))))) ============================================================= Again, the result is a web page but with nothing between the body tags. If I replace the code in the for loop with println statements, and direct the code to the repl - forgetting about the web page stuff (ie. the call to main-layout), the resultset gets printed - BUT - the issue is with building up the string. Thanks again. ~Aki

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• convert old repository to mercurial

  - by nedlud

  I've been playing around with different versioning systems to find one I'm comfortable with. I started with SVN (lets call this version of the project "f1"), then changed over to GIT. But I didn't know how to convert the old SVN repo to GIT, so I just copied the folder, deleted the .svn stuff, and turned it into a GIT repo (lets call this copied version "f2"). Now I'm playing around with Mercurial and was very pleased to find that it has a Tortoise client for Windows. I was also please to find how easy it was to convert the GIT repo into Mercurial, so I preserved the history (I still cloned it first, just in case. So I'm calling this hg version "f3"). But now what I'm wondering is: what do I do with the old SVN repo that still holds my history from before I played with GIT? I guess I can convert the old SVN repo to Mercurial, but can I then merge those two histories into the one repository so I have a complete set of histories in one place? In other words, can I prepend f1 to f3?

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• deleting object with template for int and object

  - by Yokhen

  Alright so Say I have a class with all its definition, bla bla bla... template <class DT> class Foo{ private: DT* _data; //other stuff; public: Foo(DT* data){ _data = data } virtual ~Foo(){ delete _data } //other methods }; And then I have in the main method: int main(){ int number = 12; Foo<anyRandomClass>* noPrimitiveDataObject = new Foo<anyRandomClass>(new anyRandomClass()); Foo<int>* intObject = new Foo<int>(number); delete noPrimitiveDataObject; //Everything goes just fine. delete intObject; //It messes up here, I think because primitive data types such as int are allocated in a different way. return 0; } My question is: What could I do to have both delete statements in the main method work just fine? P.S.: Although I have not actually compiled/tested this specific code, I have reviewed it extensively (as well as indented. You're welcome.), so if you find a mistake, please be nice. Thank you.

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• How to determine the width of content or size a container to content

  - by ISVK

  My goal is to display the entire contents of a FlowDocument (that is, without paginating) in a column layout. It would have a fixed height, but the width would depend on the contents of the FlowDocument. My problem is: FlowDocumentReader does not automatically resize to the contents of the FlowDocument. As you see in my XAML below, FlowDocumentReader.Width is 5000 units (just a large number that can accommodate most documents) -- when I make it Auto, it just clips to the width of the ScrollViewer and paginates my stuff! Is there a proper way of solving this problem? I also made a screenshot of what this looks like now, but the ScrollViewer scrolls past the end of the document in most cases: http://i.imgur.com/3FSRl.png <ScrollViewer x:Name="scrollViewer" HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Disabled" > <FlowDocumentReader x:Name="flowDocReader" ClipToBounds="False" Width="5000" > <FlowDocument x:Name="flowDoc" Foreground="#FF404040" ColumnRuleWidth="2" ColumnGap="40" ColumnRuleBrush="#FF404040" IsHyphenationEnabled="True" IsOptimalParagraphEnabled="True" ColumnWidth="150"> <Paragraph> Lorem ipsum dolor sit amet, ...etc... </Paragraph> <Paragraph> Lorem ipsum dolor sit amet, ...etc... </Paragraph> <Paragraph> Lorem ipsum dolor sit amet, ...etc... </Paragraph> </FlowDocument> </FlowDocumentReader> </ScrollViewer>

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• Dismiss a custom dialog?

  - by YaW

  Hi, I'm trying to make a custom dialog to show a view in this dialog. This is the Builder code: //Getting the layout LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE); View layout = inflater.inflate(R.layout.custom_dialog_simple, (ViewGroup) findViewById(R.id.rlDialogSimple)); //Change Text and on click TextView tvDialogSimple = (TextView) layout.findViewById(R.id.tvDialogSimple); tvDialogSimple.setText(R.string.avisoComprobar); Button btDialogSimple = (Button) layout.findViewById(R.id.btDialogSimple); btDialogSimple.setOnClickListener(new OnClickListener() { public void onClick(View v) { //Do some stuff //Here i want to close the dialog } }); AlertDialog.Builder builder = new AlertDialog.Builder(AcPanelEditor.this); builder.setView(layout); AlertDialog alert = builder.create(); alert.show(); So, i want to dismiss the dialog in the onClick of btDialogSimple. How i can do it? I don't know how to call the dismiss method from inside a onclicklistener. My buttons have a custom layout, so i don't want to make a builder.setPositiveButton. Any ideas?

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• DBTransactions between stateless calls using GUIDs

  - by Marty Trenouth

  I'm looking to add transactional support to my DB engine and providing to Abstract Transaction Handling down to passing in Guids with the DB Action Command. The DB engine would run similar to: private static Database DB; public static Dictionary<Guid,DBTransaction> Transactions = new ...() public static void DoDBAction(string cmdstring,List<Parameter> parameters,Guid TransactionGuid) { DBCommand cmd = BuildCommand(cmdstring,parameters); if(Transactions.ContainsKey(TransactionGuid)) cmd.Transaction = Transactions[TransactionGuid]; DB.ExecuteScalar(cmd); } public static BuildCommand(string cmd, List<Parameter> parameters) { // Create DB command from EntLib Database and assign parameters } public static Guid BeginTransaction() { // creates new Transaction adding it to "Transactions" and opens a new connection } public static Guid Commit(Guid g) { // Commits Transaction and removes it from "Transactions" and closes connection } public static Guid Rollback(Guid g) { // Rolls back Transaction and removes it from "Transactions" and closes connection } The Calling system would run similar to: Guid g try { g = DBEngine.BeginTransaction() DBEngine.DoDBAction(cmdstring1, parameters,g) // do some other stuff DBEngine.DoDBAction(cmdstring2, parameters2,g) // sit here and wait for a response from other item DBEngine.DoDBAction(cmdstring3, parameters3,g) DBEngine.Commit(g) } catch(Exception){ DBEngine.Rollback(g);} Does this interfere with .NET connection pooling (other than a connection be accidently left open)? Will EntLib keep the connection open until the commit or rollback?

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• Using ant, rename a directory without knowing the full path?

  - by mixonic

  Howdy friends, Given a zipfile with an unknown directory, how can I rename or move that directory to a normalized path? <!-- Going to fetch some stuff --> <target name="get.remote"> <!-- Get the zipfile --> <get src="http://myhost.com/package.zip" dest="package.zip"/> <!-- Unzip the file --> <unzip src="package.zip" dest="./"/> <!-- Now there is a package-3d28djh3 directory. The part after package- is a hash and cannot be known ahead of time --> <!-- Remove the zipfile --> <delete file="package.zip"/> <!-- Now we need to rename "package-3d28djh3" to "package". My best attempt is below, but it just moves package-3d28djh3 into package instead of renaming the directory. --> <!-- Make a new home for the contents. --> <mkdir dir="package" /> <!-- Move the contents --> <move todir="package/"> <fileset dir="."> <include name="package-*/*"/> </fileset> </move> </target> I'm not much of an ant user, any insight would be helpful. Thanks much, -Matt

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• Auto increment with a Unit Of Work

  - by Derick

  Context I'm building a persistence layer to abstract different types of databases that I'll be needing. On the relational part I have mySQL, Oracle and PostgreSQL. Let's take the following simplified MySQL tables: CREATE TABLE Contact ( ID varchar(15), NAME varchar(30) ); CREATE TABLE Address ( ID varchar(15), CONTACT_ID varchar(15), NAME varchar(50) ); I use code to generate system specific alpha numeric unique ID's fitting 15 chars in this case. Thus, if I insert a Contact record with it's Addresses I have my generated Contact.ID and Address.CONTACT_IDs before committing. I've created a Unit of Work (amongst others) as per Martin Fowler's patterns to add transaction support. I'm using a key based Identity Map in the UoW to track the changed records in memory. It works like a charm for the scenario above, all pretty standard stuff so far. The question scenario comes in when I have a database that is not under my control and the ID fields are auto-increment (or in Oracle sequences). In this case I do not have the db generated Contact.ID beforehand, so when I create my Address I do not have a value for Address.CONTACT_ID. The transaction has not been started on the DB session since all is kept in the Identity Map in memory. Question: What is a good approach to address this? (Avoiding unnecessary db round trips) Some ideas: Retrieve the last ID: I can do a call to the database to retrieve the last Id like: SELECT Auto_increment FROM information_schema.tables WHERE table_name='Contact'; But this is MySQL specific and probably something similar can be done for the other databases. If do this then would need to do the 1st insert, get the ID and then update the children (Address.CONTACT_IDs) – all in the current transaction context.

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• YQL + PHP : how to make a facebook login

  - by Jonathan

  Hi! I was reading some stuff about the YQL api that Yahoo! has provided, I am not sure, but it appears to be a collection of lots of third party api into one common language, right? what I don't get is how to make the facebook login through it so I can get the user profile data... My project is to add a facebook(and other social networks) form login, because the website won't have his own login, people will have to use a social network to link in. Then I thought the YQL would help me out with this task so I wouldn't have to develop lots of functions to each one of the networks. Reading this http://developer.yahoo.com/yql/guide/yql-code-examples.html#sdk_yql, I understood how to make a Yahoo login so I can access some private data, but couldn't find how I could do it with facebook and others So my question... Can YQL help me with this? Can you give me a simple example of a facebook session using it within PHP? Are there alternatives to aid me in this task? thanks, Jonathan

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• How can I format Custom Data and display in autocomplete when source is an DB

  - by Andres Scarpone

  so I'm trying to get some info in the auto-complete widget like it's shown in the JQuery UI demo Demo, the only problem is they use a variable that they fill with the data they want to show, I instead want to access the data and the different description and stuff using a Data Base in MySQL, for this I have changed the source to use another php page that looks up the info. here is the code for the Auto-complete, I really don't understand the methods so I haven't changed it from the basic search. This is the JS: $(document).ready((function(){ $( "#completa" ).autocomplete({ source: "buscar.php", minLength: 1, focus: function (event, ui){ $("#completa").val(ui.item.val); return false; }; })); This is what I have in buscar.php: <?php $conec = mysql_connect(localhost, root, admin); if(!$conec) { die(mysql_error()); } else { $bd = mysql_select_db("ve_test",$conec ); if(!$bd) { die(mysql_error()); } } $termino = trim(strip_tags($_GET['term']));//Obtener el termino que envia el autocompletar $qstring = "SELECT name, descripcion FROM VE_table WHERE name LIKE '%".$termino."%'"; $result = mysql_query($qstring);//Solicitud a la Base de Datos while ($row = mysql_fetch_array($result,MYSQL_ASSOC))//Realizar un LOOP sobre los valores obtenidos { $row['value']=htmlentities(stripslashes($row['name'])); $row_set[] = $row;//build an array } echo json_encode($row_set);//Enviar los datos al autocompletar en codificacion JSON, Altamente Necesario. ?

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• Implementing a c/c++ style union as a column in MySQL

  - by user81338

  Friends, I have a strange need and cannot think my way through the problem. The great and mighty Google is of little help due to keyword recycling (as you'll see). Can you help? What I want to do is store data of multiple types in a single column in MySQL. This is the database equivalent to a C union (and if you search for MySQL and Union, you obviously get a whole bunch of stuff on the UNION keyword in SQL). [Contrived and simplified case follows] So, let us say that we have people - who have names - and STORMTROOPERS - who have TK numbers. You cannot have BOTH a NAME and a TK number. You're either BOB SMITH -or- TK409. In C I could express this as a union, like so: union { char * name; int tkNo; } EmperialPersonnelRecord; This makes it so that I am either storing a pointer to a char array or an ID in the type EmperialPersonnelRecord, but not both. I am looking for a MySQL equivalent on a column. My column would store either an int, double, or varchar(255) (or whatever combination). But would only take up the space of the largest element. Is this possible? (of course anything is possible given enough time, money and will - I mean is it possible if I am poor, lazy and on a deadline... aka "out of the box")

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• Recursive problem...

  - by Chronos

  Guys, I'm new to java and multithreading..... and I have a following problem: I have two classes running in two different threads. Class A and Class B. Class A has the method "onNewEvent()". Once that method is invoked, it will ask class B to do some work. As soon as B finishes the work it invokes onJobDone() method of the class A. Now... here comes the problem... what I want is to create new job within onJobDone() method and to send it again to B. here is what I do (pseudo code) ... in the sequence of execution A.onNewEvent(){ //create job //ask B to do it B.do() } B.do{ // Do some stuff A.jobDone() } A.onJobDOne(){ B.do() //doItAgain // print message "Thank you for doing it" } The problem is... that message "Thank you for doing it" never gets printed... in fact, when onJobDone() method is invoked, it invokes B.do()... because B.do() is very fast, it invokes onJobDone() immediatly... so execution flow never comes to PRINT MESSAGE part of code... I suppose this is one of the nasty multithreading problems.... any help would be appreciated.

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• Sequential access to asynchronous sockets

  - by Lars A. Brekken

  I have a server that has several clients C1...Cn to each of which there is a TCP connection established. There are less than 10,000 clients. The message protocol is request/response based, where the server sends a request to a client and then the client sends a response. The server has several threads, T1...Tm, and each of these may send requests to any of the clients. I want to make sure that only one of these threads can send a request to a specific client at any one time, while the other threads wanting to send a request to the same client will have to wait. I do not want to block threads from sending requests to different clients at the same time. E.g. If T1 is sending a request to C3, another thread T2 should not be able to send anything to C3 until T1 has received its response. I was thinking of using a simple lock statement on the socket: lock (c3Socket) { // Send request to C3 // Get response from C3 } I am using asynchronous sockets, so I may have to use Monitor instead: Monitor.Enter(c3Socket); // Before calling .BeginReceive() And Monitor.Exit(c3Socket); // In .EndReceive I am worried about stuff going wrong and not letting go of the monitor and therefore blocking all access to a client. I'm thinking that my heartbeat thread could use Monitor.TryEnter() with a timeout and throw out sockets that it cannot get the monitor for. Would it make sense for me to make the Begin and End calls synchronous in order to be able to use the lock() statement? I know that I would be sacrificing concurrency for simplicity in this case, but it may be worth it. Am I overlooking anything here? Any input appreciated.

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• A feeling that I'm not that good developer

  - by Karim

  Hi, Im having a strange feeling, but let me first introduce myself as a software developer. I started to program when I was still a kid, I had about 10 or 11 years. I really enjoy my work and never get bored from it. It's amazing how somebody could be paid for what he really likes to do and would be doing it anyway even for free. WHen I first started to program, I was feeling proud of what I was doing, each application I built was for me a success and after 2-3 year I had a feeling that I'm a coding guru. It was a nice feeling ;-) But the more I was in the field, the more types of software I started to develop I was starting to have a feeling that I'm completely wrong in that I'm guru. I felt that I'm not even a mediocre developer. Each new field I start to work on is giving me this feeling. Like when I once developed a device driver for a client, I saw how much I need to learn about device drivers. When I developed a video filter for an application, I saw how much do I still need to learn about DirectShow, Color Spaces, and all the theory behind that. The worst thing was when I started to learn algorithms. It was several years ago. I knew then the basic structures and algorithms like the sorting, some types of trees, some hashtables, strings etc.. and when I really wanted to learn a group of structures I learned about 5-6 new types and saw that in fact even this small group has several hundred subtypes of structures. It's depressing how little time people have in their lives to learn all this stuff. I'm now a software developer with about 10 years of experience and I still feel that I'm not a proficient developer when I think about things that others do in the industry. Is this normal what I'm experiencing or is it a sign of a destructive excessive ambition? Thanks in advance for any comments.

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