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  • Basic PHP OOPS Query

    - by appu
    Ok. I am starting out OOPS in PHP. Created a couple of classes: customer(parent) and sales(child) class that inherits from parent class. Created another testcustomer.php in which a new sales object is created however the salesprint() function defined in the sales class does not echo out customer's name though it is set to be "Jane" in the class.customer.php(parent). My thinking is that when sales class extends customer class PHP automatically includes all the code from class.customer.php to sales.customer.php and therefore the constructor in parent class set $name to "Jane". Here is the code: class.customer.php <?php class customer{ private $name; private $cust_no; public function __construct($customerid) { $this->name = 'Jane'; $this->cust_no = $customerid; } } ?> class.sales.php <?php require_once('class.customer.php'); class sales extends customer{ public function salesprint($customerid) { echo "Hello $this->name this is a print of your purchased products"; } } ?> testcustomer.php require_once('class.sales.php'); $objsales = new sales(17); $objsales->salesprint(17); ?> The Output I get Hello this is a print of your purchased products. What am i doing wrong ? thanks romesh

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  • How to use keyword this in a mouse wrapper in right context in Javascript?

    - by MartyIX
    Hi, I'm trying to write a simple wrapper for mouse behaviour. This is my current code: function MouseWrapper() { this.mouseDown = 0; this.OnMouseDownEvent = null; this.OnMouseUpEvent = null; document.body.onmousedown = this.OnMouseDown; document.body.onmouseup = this.OnMouseUp; } MouseWrapper.prototype.Subscribe = function (eventName, fn) { // Subscribe a function to the event if (eventName == 'MouseDown') { this.OnMouseDownEvent = fn; } else if (eventName == 'MouseUp') { this.OnMouseUpEvent = fn; } else { alert('Subscribe: Unknown event.'); } } MouseWrapper.prototype.OnMouseDown = function () { this.mouseDown = 1; // Fire event $.dump(this.OnMouseDownEvent); if (this.OnMouseDownEvent != null) { alert('test'); this.OnMouseDownEvent(); } } MouseWrapper.prototype.OnMouseUp = function () { this.mouseDown = 0; // Fire event if (this.OnMouseUpEvent != null) { this.OnMouseUpEvent(); } } From what I gathered it seems that in MouseWrapper.prototype.OnMouseUp and MouseWrapper.prototype.OnMouseDown the keyword "this" doesn't mean current instance of MouseWrapper but something else. And it makes sense that it doesn't point to my instance but how to solve the problem? I want to solve the problem properly I don't want to use something dirty. My thinking: * use a singleton pattern (mouse is only one after all) * pass somehow my instance to OnMouseDown/Up - how? Thank you for help!

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  • Socket.Recieve Failing When Multithreaded

    - by Qua
    The following piece of code runs fine when parallelized to 4-5 threads, but starts to fail as the number of threads increase somewhere beyond 10 concurrentthreads int totalRecieved = 0; int recieved; StringBuilder contentSB = new StringBuilder(4000); while ((recieved = socket.Receive(buffer, SocketFlags.None)) > 0) { contentSB.Append(Encoding.ASCII.GetString(buffer, 0, recieved)); totalRecieved += recieved; } The Recieve method returns with zero bytes read, and if I continue calling the recieve method then I eventually get a 'An established connection was aborted by the software in your host machine'-exception. So I'm assuming that the host actually sent data and then closed the connection, but for some reason I never recieved it. I'm curious as to why this problem arises when there are a lot of threads. I'm thinking it must have something to do with the fact that each thread doesn't get as much execution time and therefore there are some idle time for the threads which causes this error. Just can't figure out why idle time would cause the socket not to recieve any data.

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  • How to put JFrame into existing JPanel in Java Swing?

    - by suud
    I have an open-source java swing application like this: http://i47.tinypic.com/dff4f7.jpg You can see in the screenshot, there is a JPanel divided into two area, left and right area. The left area has many text links. When I click the SLA Criteria link, it will pop-up the SLA Criteria window. The pop-up window is JFrame object. Now, I'm trying to put the pop-up window into right area of the JPanel, so that means no pop-up window anymore, i.e. when I click the SLA Criteria link, its contents will be displayed at the right area of the JPanel. The existing content of the right area of JPanel will not be used anymore. The example illustration (note: it's made and edited using image editor, this is not the real screenshot of working application) is like this: http://i48.tinypic.com/5vrxaa.jpg So, I would like to know is there a way to put JFrame into JPanel? I'm thinking of using JInternalFrame, is it possible? Or is there another way? UPDATE: Source code: http://pastebin.com/tiqRbWP8 (VTreePanel.java, this is the JPanel) http://pastebin.com/330z3yuT (CPanel.java, this is the super class of VTreePanel) http://pastebin.com/MkNsbtjh (AWindow.java, this is the JFrame, pop-up window) http://pastebin.com/2rsppQeE (CFrame.java, this is the super class of AWindow)

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  • Deploying a WAR to tomcat only using a context descriptor

    - by DanglingElse
    i need to deploy a web application in WAR format to a remote tomcat6 server. The thing is that i don't want to do that the easy way, meaning not just copy/paste the WAR file to /webapps. So the second choice is to create a unique "Context Descriptor" and pointing this out to the WAR file. (Hope i got that right till here) So i have a few questions: Is the WAR file allowed to be anywhere in the file system? Meaning can i copy the WAR file anywhere in the remote file system, except /webapps or any other folder of the tomcat6 installation? Is there an easy way to test whether the deployment was successful or not? Without using any browser or anything, since i'm reaching to the remote server only via SSH and terminal. (I'm thinking ping?) Is it normal that the startup.sh/shutdown.sh don't exist? I'm not the admin of the server and don't know how the tomcat6 is installed. But i'm sure that in my local tomcat installations these files are in /bin and ready to use. I mean you can still start/restart/stop the tomcat etc., but not with the these -standard?- scripts. Thanks a lot.

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  • Is this a bug in plist or Xcode?

    - by Pedro
    G'day All If you create a date item in the plist editor of Xcode or Apple's standalone plist editor you get something of the form <date>2010-05-29T10:30:00Z</date> which is a nice well formed ISO date at UTC (indicated by the "Z"). Because I'm in timezone UTC +10 when that's read into my app & then displayed I get 8:30 PM out, still good. However if that is a time in my timezone it should be <date>2010-05-29T10:30:00+10</date> (replacing "Z" with my timezone offset). All of my attempts at reading such dates into my iPhone app have had the plist rejected as if it is malformed & editing a plist with such a date in Apple's editors changed the "+10" to "Z" without adjusting the time. Do others think I'm correct in thinking this is a bug in either plist or Xcode? My feeling is that the implementation of ISO date & time in plist is incomplete. Cheers, Pedro :)

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  • OSGI, Servlets and JPA hello world / tutorial / example

    - by Kamil
    I want to build a web application which basically is a restful web-service serving json messages. I would like it to be as simple as possible. I was thinking about using servlets (with annotations). JPA as a database layer is a must - Toplink or Hibernate. Preferably working on Tomcat. I want to have app divided into modules serving different functionality (auth service, customer service, etc..). And I would like to be able to update those modules without reinstalling whole application on the server - like eclipse plugins, user is notified (when he enters webapp's home url) that update is available, clicks it, and app is downloading and installing updated module. I think this functionality can be made with OSGI, but I can't find any example code, or tutorial with simple hello world updatable servlet providing some data from database through jpa. I'm looking for an advice: - Is OSGI the right tool for this or it can be done with something simpler? - Where can I find some examples covering topic (or topics) which I need for this project. - Which OSGI implementation would be best-simplest for this task. *My knowledge of OSGI is basic. I know how bundles are described, I understand concept of OSGI container and what it does. I have never created any OSGI app yet.

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  • The following grammar is LL1, SLR, LR(1), LALR?

    - by Mike
    P - {D ; C} D - d; D| d C - c; C | c a) Is the grammar LL(1)? Explain your answer. b) Is the grammar SLR(1)? Explain your answer. c) Is the grammar LR(1)? Explain your answer. d) Is the grammar LALR? Explain your answer. As for my answers I actually got no for them all... so I'm thinking I did something wrong Here is my explanation. a) It is not LL(1) because it is not left factored. b) It is not SLR, because of the transition diagram item 2 ( which is... ) D- d . ; D D- d . We need to consult the follow set, Follow(D) = ; Therefore this is not SLR c) It is not LR(1) because of... item 1 P- {D.;C} , $ D- .d;D , ; D- .d , ; item 2 D- d.; D , ; D- d. , ; item 3 D- d; . D , ; D- .d;D , ; D- .d , ; Since item 2 goes to item 3 with ;, AND "D- d."'s (in item 2) look ahead token is also ;. this causes a reduce to shift conflict, therefore this grammar is not LR(1) d) This grammar is not LALR because it is not LR(1) Thanks for your help!

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  • How to establish a socket connection from iPhone to a Apache server and communicate via PHP?

    - by candoyo
    Hi, I am working on an iPhone game which is depended on a LAMP server. I want to create a "event" based system where the apache server sends an event to the iphone. For this, I am thinking of using "CFStreamCreatePairWithSocketToHost" to connect to port 80 of the apache server. I am able to successfully connect to the server and open a read and write stream via the iPhone, but I am not sure how to send data to the iphone using PHP running from the LAMP server to the iPhone. I think I can use fsockopen in php to open a socket connection and write data to that socket. I tired running this code $fp = fsockopen("tcp://localhost", 80, $errno, $errstr); if (!$fp) { echo "ERROR: $errno - $errstr<br />\n"; } else { echo"writing to socket "; fwrite($fp, "wwqeqweqw eqwe qwe \n"); //echo fread($fp, 26); fclose($fp); echo "done"; } But, I dont see anything being read on the iphone.. Any idea what's going on, or how to accomplish this? Thanks!

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  • PHP Preserve scope when calling a function

    - by Joshua
    I have a function that includes a file based on the string that gets passed to it i.e. the action variable from the query string. I use this for filtering purposes etc so people can't include files they shouldn't be able to and if the file doesn't exist a default file is loaded instead. The problem is that when the function runs and includes the file scope, is lost because the include ran inside a function. This becomes a problem because I use a global configuration file, then I use specific configuration files for each module on the site. The way I'm doing it at the moment is defining the variables I want to be able to use as global and then adding them into the top of the filtering function. Is there any easier way to do this, i.e. by preserving scope when a function call is made or is there such a thing as PHP macros? Edit: Would it be better to use extract($_GLOBALS); inside my function call instead? Edit 2: For anyone that cared. I realised I was over thinking the problem altogether and that instead of using a function I should just use an include, duh! That way I can keep my scope and have my cake too.

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  • xcode project-/target-settings-syntax for linker flag force_load on iPhone

    - by Kaiserludi
    Hi all. I am confronted with the double bind, that on the one hand for one of the 3rd party static libraries, my iPhone application uses, the linker flag -all_load has to be set in the application project- or target settings, otherwise the app crashes at runtime not finding some symbols, called internally from the lib, on the other hand for another 3rd party static lib -all_load must not be set on application level, or the app won't build thanks to a "duplicate symbols"-linker error. To solve this issue I now want to use force_load instant of load_all, as it due to documentation it does the same like all_load, but only for the passed path or lib-file, instead of all libs. The problem with force_load is, I do not have a clue, how to pass a path or file as parameter with it, when passing it via xcode project- or target-settings. All syntax-possibilities coming to my mind either lead into xcode thinking its another linker flag instead of a parameter to the previous one, or the linker is throwing syntax related errors or the flag simply does nothing at all in comparison to not being set. I also opened the .pbxproj-file in a text-editor to edit it to the correct command line syntax manually, but when reloading the project with xcode, it auto changes the syntax into interpreting the parameter to force_load as a separate flag. Anyone having an idea on this issue? Thx, Kaiserludi.

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  • Checking if any of a list of values falls within a table of ranges

    - by Conspicuous Compiler
    I'm looking to check whether any of a list of integers fall in a list of ranges. The ranges are defined in a table defined something like: # Extra Type Field Default Null Key 0 int(11) rangeid 0 NO PRI 1 int(11) max 0 NO MUL 2 int(11) min 0 NO MUL Using MySQL 5.1 and Perl 5.10. I can check whether a single value, say 7, is in any of the ranges with a statement like SELECT 1 FROM range WHERE 7 BETWEEN min AND max If 7 is in any of those ranges, I get a single row back. If it isn't, no rows are returned. Now I have a list of, say, 50 of these values, not stored in a table at present. I assemble them using map: my $value_list = '(' . ( join ', ', map { int $_ } @values ) . ')' ; I want to see if any of the items in the list fall inside of any of the ranges, but am not particularly concerned with which number nor which range. I'd like to use a syntax such as: SELECT 1 FROM range WHERE (1, 2, 3, 4, 5, 6, 7, 42, 309, 10000) BETWEEN min AND max MySQL kindly chastises me for such syntax: Operand should contain 1 column(s) I pinged #mysql who were quite helpful. However, having already written this up by the time they responded and thinking it'd be helpful to fix the answer in a more permanent medium, I figured I'd post the question anyhow. Maybe SO will provide a different solution?

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  • How do I switch out Views in a Cocoa application?

    - by David Garcia
    So I'm beginning to learn how to use Cocoa. I think I've pretty much got it but I'm hung up on creating and switching views. I'm rewriting a game I made a little bit ago for practice. All I want is one window (preferably not resizable) and I want to be able to switch out views for different screens in the game. First, I have the main menu (Start Game, High Scores, Exit). Then I need a window for each screen (Gameplay screen, Highscore screen). What I'm getting confused with is how to design this. I looked up NSViewController thinking it manages views but it doesn't. It only manages one view by loading it really. I don't understand why I'd need to use NSViewController then. Couldn't I just have a window class that contains multiple subclasses of NSView and load them like that? I'm not sure I understand the purpose of the ViewController. Does my Window Class really need to subclass NSWindowController? I was trying to follow the example of Apple's ViewController example and it has a window controller class that's a subclass of NSWindowController. I don't see what the purpose was of subclassing that. All NSWindowController seems to add is - initWithPath:(NSString *)newPath but I fail to see the use in that either when I can just edit the plist file to open the window on start up. Apple's example also has an NSView variable and an NSViewController variable. Don't you only need one variable to store the current view? Thanks in advance guys, I'm really confused as to how this works.

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  • Passing javascript object to webservice via Jquery ajax

    - by kralco626
    I have a webservice that returns an object [WebMethod] public List<User> ContractorApprovals() I also have a webservice that accepcts an object [WebMethod] public bool SaveContractor(Object u) When I make my webservice calls via Jquery: function ServiceCall(method, parameters, onSucess, onFailure) { var parms = "{" + (($.isArray(parameters)) ? parameters.join(',') : parameters) + "}"; // to json $.ajax({ type: "POST", url: "services/"+method, data: parms, contentType: "application/json; charset=utf-8", dataType: "json", success: function(msg) { if (typeof onSucess == 'function' || typeof onSucess == 'object') onSucess(msg.d); }, error: function(msg, err) { $("#dialog-error").dialog('open');} }); I can call the first one just fine. My onSucess function gets passed a javascript object exactly structured like my User object on the service. However, I am now having trouble getting the object back to the server. I'm accepting Object as a parameter on the server side so I can't inagine there is an issue there. So I'm thinking something is wrong with the parms on the client side but i'm not sure what... I am doing something to the effect ServiceCall("AuthorizationManagerWorkManagement.asmx/ContractorApprovals", "", function(data,args){$("#div").data('user',data[0])}, null) then ServiceCall("AuthorizationManagerWorkManagement.asmx/SaveContractor", $("#div").data('user'), //These also do not work: "{'u': ' + $("#div").data("user") + '}", NOR JSON.stringify({u: userObject}) function(data,args){(alert(data)}, null) I know the first service call works, I can get the data. The second one is causing the "onFailure" method to execute rather then "OnSuccess". Any ideas?

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  • Design patterns for Agent / Actor based concurrent design.

    - by nso1
    Recently i have been getting into alternative languages that support an actor/agent/shared nothing architecture - ie. scala, clojure etc (clojure also supports shared state). So far most of the documentation that I have read focus around the intro level. What I am looking for is more advanced documentation along the gang of four but instead shared nothing based. Why ? It helps to grok the change in design thinking. Simple examples are easy, but in a real world java application (single threaded) you can have object graphs with 1000's of members with complex relationships. But with agent based concurrency development it introduces a whole new set of ideas to comprehend when designing large systems. ie. Agent granularity - how much state should one agent manage - implications on performance etc or are their good patterns for mapping shared state object graphs to agent based system. tips on mapping domain models to design. Discussions not on the technology but more on how to BEST use the technology in design (real world "complex" examples would be great).

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  • looking to streamline my RSS feed mashup

    - by Mark Cejas
    Hello crafty developers, I have aggregated RSS feeds from various sources with RSSowl, fetching directly from the social mention API. The RSS feeds are categorized into the following major categories: blogs, news, twitter, Q&A and social networking sites. Each major category is nested with a common group of RSS feeds that represent a particular client/brand ontology. Merging these feeds into the RSSowl reader application, allows me to conduct and save refined search queries (from the aggregated data) into a single file - that I can then tag and further segment for analysis. This scheme is utilized for my own research needs and has helped me considerably. However, I find this RSS mashup scheme kinda clumsy, it requires quite a bit of time to initially organize all of the feeds and I would like to be able to do further natural language processing to the data as well as eventually be able to rank the collected list of URL's into some order of media prominence - right I don't want to pay the ridiculous radian6 web analytics fees, when my intuition is telling me that with a bit of 'elbow grease' I can maybe leverage some available resources online to develop a functional low scale web mining application and get some good intelligence from it. I am now starting to learn a little about computer science - my background is in physical science/statistics so is my thinking in the right track? So, I guess I am imagining an application that allows me to query in a refined manner. A manner that allows me to search for keyword combinations, applying AND/OR operators, selectively focus my queries into particular sources - like a collection of blogs or twitter, or social networking communities, then save the results of my queries into a structured format that can then be manipulated and explored. Am I dreaming? I just had to get all of this out. any bit of advice and insight would be hugely appreciated. my best, Mark

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  • 60K+ Sprites on the 360?

    - by Jeffrey Kern
    Hey everyone, Just wondering - throwing ideas in my head - about starting a new XNA project for the 360. I would like it to be retro-old school, and emulating scanlines and color palettes and such. As part of this idea, what I would ideally like to do is manually draw each and every pixel of the screen. So, worst-case scenario I would have to draw about 60K sprites on a 252x240 resolution (I think thats correct). 60K sprites on the screen at a time. So, before I even attempt to code this - would the XBOX 360 be able to keep up with this even? That is a lot of sprites, but they aren't big sprites, and the texture data needed would be non-existant. However, I guess how this project would be implemented would make it or break it, but all I was thinking was coming up with a 2D array and mapping which color value would need to be drawn at that point. Of course, this is watered down talk right now. But what you all suggest? EDIT: Each sprite would represent one pixel. E.g., a sprite at 0,0. Another at 0,1. etc.

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  • How good is the memory mapped Circular Buffer on Wikipedia?

    - by abroun
    I'm trying to implement a circular buffer in C, and have come across this example on Wikipedia. It looks as if it would provide a really nice interface for anyone reading from the buffer, as reads which wrap around from the end to the beginning of the buffer are handled automatically. So all reads are contiguous. However, I'm a bit unsure about using it straight away as I don't really have much experience with memory mapping or virtual memory and I'm not sure that I fully understand what it's doing. What I think I understand is that it's mapping a shared memory file the size of the buffer into memory twice. Then, whenever data is written into the buffer it appears in memory in 2 places at once. This allows all reads to be contiguous. What would be really great is if someone with more experience of POSIX memory mapping could have a quick look at the code and tell me if the underlying mechanism used is really that efficient. Am I right in thinking for example that the file in /dev/shm used for the shared memory always stays in RAM or could it get written to the hard drive (performance hit) at some point? Are there any gotchas I should be aware of? As it stands, I'm probably going to use a simpler method for my current project, but it'd be good to understand this to have it in my toolbox for the future. Thanks in advance for your time.

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  • Sync two SqlExpress using NHibernate

    - by Christian
    Hello, I am creating a simple project management system which uses NHibernate for object storage. The underlying database is SQL express (at least currently for development). The client runs on either the desktop or laptop. I know I could use web-services and store the DB only on the desktop, but this would force the desktop to be available all the time. I am currently thinking about duplicating the DB, having two instances with "different data". To clarify, we are not talking about a productive app here, its a prototype. One way to achieve this very simple would be the following process: Client: Check if desktop DB is available (through web service) Client: If yes, use desktop storage, no problem here Client: If not, use own DB as storage Client: Poll desktop regulary, as soon as it comes on, sync Client: Switch to desktop storage ... Desktop: Do not attempt any DB operation before checking for required sync Desktop: If sync needed, do it... My question is now, how would you sync? Assume 4 or 5 types of objects, all have GUID as identifiers. Would you always manually "lazy load" all objects of a certain type and feed them to the DB. Would you always drop the whole desktop DB in case the client DB may be newer and out of sync? Again, I want to stress out, I am not assuming any conflicts or stale data, I basically just want to "copy the whole DB from the client". Would you use NHibernate for this? Or would you separate the copy process? When I think about it, my questions comes down to this: Is there any function from NHibernate: SyncDBs_SourceWins_(SourceDB, TargetDB) Thanks for help, Chris

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  • How can I make keyword order more relevant in my search?

    - by Atomiton
    In my database, I have a keywords field that stores a comma-delimited list of keywords. For example, a Shrek doll might have the following keywords: ogre, green, plush, hero, boys' toys A "Beanie Baby" doll ( that happens to be an ogre ) might have: beanie baby, kids toys, beanbag toys, soft, infant, ogre (That's a completely contrived example.) What I'd like to do is if the consumer searches for "ogre" I'd like the "Shrek" doll to come up higher in the search results. My content administrator feels that if the keyword is earlier in the list, it should get a higher ranking. ( This makes sense to me and it makes it easy for me to let them control the search result relevance ). Here's a simplified query: SELECT p.ProductID AS ContentID , p.ProductName AS Title , p.ProductCode AS Subtitle , 100 AS Rank , p.ProductKeywords AS Keywords FROM Products AS p WHERE FREETEXT( p.ProductKeywords, @SearchPredicate ) I'm thinking something along the lines of replacing the RANK with: , 200 - INDEXOF(@SearchTerm) AS Rank This "should" rank the keyword results by their relevance I know INDEXOF isn't a SQL command... but it's something LIKE that I would like to accomplish. Am I approaching this the right way? Is it possible to do something like this? Does this make sense?

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  • Use date operations on a computed field filter in a view

    - by stephenhay
    I'd like to expose a filter in Views based on a Computed Field. This field should utilize the date operation "less than". Apparently, a date type is not available to computed field (varchar is). However, using varchar results in views treating the field as a string rather than as a date, without the operation I'm looking for. So I tried using a timestamp instead of a date, which allowed me to use an integer data type. The exposed view gives me a "less than" operation, but as it's still not a date, the user must type in a timestamp. Not handy. So I'm thinking the best way to do this is to create a new (hidden) CCK field which is a date field, and set the value of this field to the value of the Computed Field. I can then use the new CCK field for my exposed filter. But I'm not getting anywhere with this, as I'm unsure how to set another CCK field with a Computed Field. To return the value to the computed field itself, I'm using the standard: $node_field[0]['value'] = $newestdate; I would like to set the value of the new CCK field to $newestdate as well. Can anyone help?

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  • How to report progress of a JavaScript function?

    - by LambyPie
    I have a JavaScript function which is quite long and performs a number of tasks, I would like to report progress to the user by updating the contents of a SPAN element with a message as I go. I tried adding document.getElementById('spnProgress').innerText = ... statements throughout the function code. However, whilst the function is executing the UI will not update and so you only ever see the last message written to the SPAN which is not very helpful. My current solution is to break the task up into a number of functions, at the end of each I set the SPAN message and then "trigger" the next one with a window.setTimeout call with a very short delay (say 10ms). This yields control and allows the browser to repaint the SPAN with the updated message before starting the next step. However I find this very messy and difficult to follow the code, I'm thinking there must be a better way. Does anyone have any suggestions? Is there any way to force the SPAN to repaint without having to leave the context of the function? Thanks

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  • Ways to update a dependent table in the same MySQL transaction?

    - by codie
    I need to update two tables inside a single transaction. The individual queries look something like this: 1. INSERT INTO t1 (col1, col2) VALUES (val1, val2) ON DUPLICATE KEY UPDATE col2 = val2; If the above query causes an insert then I need to run the following statement on the second table: 2. INSERT INTO t2 (col1, col2) VALUES (val1, val2) ON DUPLICATE KEY UPDATE col2 = col2 + val2; otherwise, 3. UPDATE t2 SET col2 = col2 - old_val2 + val2 WHERE col1 = val1; -- old_val2 is the value of t1.col2 before it was updated Right now I run a SELECT on t1 first, to determine whether statement 1 will cause an insert or update on t1. Then I run statement 1 and either of 2 and 3 inside a transaction. What are the ways in which I can do all of these inside one transaction itself? The approach I was thinking of is the following: UPDATE t2, t1 set t2.col2 = t2.col2 - t1.col2 WHERE t1.col1 = t2.col2 and t1.col1 = val1; INSERT INTO t1 (col1, col2) VALUES (val1, val2) ON DUPLICATE KEY UPDATE col2 = val2; INSERT INTO t2, t1 (t2.col1, t2.col2) VALUES (t1.col1, t1.col2) ON DUPLICATE KEY UPDATE t2.col2 = t2.col2 + t1.col2 WHERE t1.col1 = t2.col2 and t1.col1 = val1; Unfortunately, there's no multi-table INSERT... ON DUPLICATE KEY UPDATE in MySQL 5.0. What else could I do?

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  • Rails: creating a custom data type, to use with generator classes and a bunch of questions related t

    - by Shyam
    Hi, After being productive with Rails for some weeks, I learned some tricks and got some experience with the framework. About 10 days ago, I figured out it is possible to build a custom data type for migrations by adding some code in the Table definition. Also, after learning a bit about floating points (and how evil they are) vs integers, the money gem and other possible solutions, I decided I didn't WANT to use the money gem, but instead try to learn more about programming and finding a solution myself. Some suggestions said that I should be using integers, one for the whole numbers and one for the cents. When playing in script/console, I discovered how easy it is to work with calculations and arrays. But, I am talking to much (and the reason I am, is to give some sufficient background). Right now, while playing with the scaffold generator (yes, I use it, because I like they way I can quickly set up a prototype while I am still researching my objectives), I like to use a DRY method. In my opinion, I should build a custom "object", that can hold two variables (Fixnum), one for the whole, one for the cents. In my big dream, I would be able to do the following: script/generate scaffold Cake name:string description:text cost:mycustom Where mycustom should create two integer columns (one for wholes, one for cents). Right now I could do this by doing: script/generate scaffold Cake name:string description:text cost_w:integer cost_c:integer I had also had an idea that would be creating a "cost model", which would hold two columns of integers and create a cost_id column to my scaffold. But wouldn't that be an extra table that would cause some kind of performance penalty? And wouldn't that be defy the purpose of the Cake model in the first place, because the costs are an attribute of individual Cake entries? The reason why I would want to have such a functionality because I am thinking of having multiple "costs" inside my rails application. Thank you for your feedback, comments and answers! I hope my message got through as understandable, my apologies for incorrect grammar or weird sentences as English is not my native language.

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  • optimize 2D array in C++

    - by Hristo
    I'm dealing with a 2D array with the following characteristics: const int cols = 500; const int rows = 100; int arr[rows][cols]; I access array arr in the following manner to do some work: for(int k = 0; k < T; ++k) { // for each trainee myscore[k] = 0; for(int i = 0; i < N; ++i) { // for each sample for(int j = 0; j < E[i]; ++j) { // for each expert myscore[k] += delta(i, anotherArray[k][i], arr[j][i]); } } } So I am worried about the array 'arr' and not the other one. I need to make this more cache-friendly and also boost the speed. I was thinking perhaps transposing the array but I wasn't sure how to do that. My implementation turns out to only work for square matrices. How would I make it work for non-square matrices? Also, would mapping the 2D array into a 1D array boost the performance? If so, how would I do that? Finally, any other advice on how else I can optimize this... I've run out of ideas, but I know that arr[j][i] is the place where I need to make changes because I'm accessing columns by columns instead of rows by rows so that is not cache friendly at all. Thanks, Hristo

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