Search Results

Search found 9889 results on 396 pages for 'pointer speed'.

Page 332/396 | < Previous Page | 328 329 330 331 332 333 334 335 336 337 338 339  | Next Page >

  • Problem adding and removing a jquery tab to the existing tabs dynamically.

    - by kranthi
    hi everyone, I have a href tag, upon clicking it a new jquery tab is added to the existing tabs,using the following js. $(function() { //DECLARE FUNCTION: removetab var removetab = function(tabselector, index) { $(".removetab").click(function(){ $(tabselector).tabs('remove',index); }); }; //create tabs $("#tabs").tabs({ add: function(event, ui) { //select newely opened tab $(this).tabs('select',ui.index); //load function to close tab removetab($(this), ui.index); }, show: function(event, ui) { //load function to close selected tabs removetab($(this), ui.index); } }); //load new tab $(".addtab").click(function(){ var href=$(this).attr("href"); var title=$(this).attr("title"); $("#tabs").tabs( 'add' , href , title+' <span class="removetab ui-icon ui-icon-circle-close" style="float:right; margin: -2px -10px 0px 3px; cursor:pointer;"></span>'); return false; }); }); and <a class="addtab" title="Tab Label" href="HTMLPage.htm">Add Tab</a> If the href attribute for 'a' tag corresponds to a '.htm' page I am able to add & remove the tab successfully.Where as if it corresponds to a '.aspx' page I am able to add a new tab ,but unable to remove the tab upon clicking on the 'close' sign next to the tab title. Please help. Thanks in advance

    Read the article

  • gcc, strict-aliasing, and horror stories

    - by Joseph Quinsey
    In http://stackoverflow.com/questions/2906365/gcc-strict-aliasing-and-casting-through-a-union I asked whether anyone had encountered problems with union punning through pointers. So far, the answer seems to be No. This question is broader: do you have any horror stories about gcc and strict-aliasing? Background: Quoting from AndreyT's answer in http://stackoverflow.com/questions/2771023/c99-strict-aliasing-rules-in-c-gcc/2771041#2771041: "Strict aliasing rules are rooted in parts of the standard that were present in C and C++ since the beginning of [standardized] times. The clause that prohibits accessing object of one type through a lvalue of another type is present in C89/90 (6.3) as well as in C++98 (3.10/15). ... It is just that not all compilers wanted (or dared) to enforce it or rely on it." Well, gcc is now daring to do so, with its -fstrict-aliasing switch. And this has caused some problems. See, for example, the excellent article http://davmac.wordpress.com/2009/10/ about a Mysql bug, and the equally excellent discussion in http://cellperformance.beyond3d.com/articles/2006/06/understanding-strict-aliasing.html. Some other less-relevant links: http://stackoverflow.com/questions/1225741/performance-impact-of-fno-strict-aliasing http://stackoverflow.com/questions/754929/strict-aliasing http://stackoverflow.com/questions/262379/when-is-char-safe-for-strict-pointer-aliasing http://stackoverflow.com/questions/725138/how-to-detect-strict-aliasing-at-compile-time So to repeat, do you have a horror story of your own? Problems not indicated by -Wstrict-aliasing would, of course, be preferred. And other C compilers are also welcome.

    Read the article

  • Helping Rails Newbies identify version-specific information on web pages

    - by corprew
    I am trying to help some people getting started programming on rails identify which version that advice found on web pages corresponds to, and am seeking advice and/or guides on how to do it so they don't have to rely on me and/or waste time trying outdated advice. Narrative: I am helping some people get up to speed on rails development, and their stock response to running into problems is searching google for advice. They're using 2.3.5 and thinking of moving to 3. The problem they're running into is that there's a lot of advice out there specific to older rails versions (2.2 for example being popular) that isn't identified. I can usually figure out when the pages are old pretty easily, but they can't (yet.) It seems like random web page authors don't identify which version they're using when they're using the current version, and not all pages are dated. This seems to be a general problem that will get worse -- current unadorned advice is usually 2.3.5 and older unadorned advice is 2.2.x at this point, but people are moving / will be moving to version 3 over the next while and newbies will be stuck looking at a bunch of deprecated/incompatible 2.3.x advice without realizing which version it is. Any advice / pointers / telltales?

    Read the article

  • Javascript changing source of an image

    - by Pete Herbert Penito
    Hi Everyone! I have some javascript which runs a timer that animates something on the website. It all works perfectly but I want to get an image to change when the animation is run, It uses jquery: if(options.auto && dir=="next" && !clicked) { timeout = setTimeout(function(){ if (document.images['bullet1'].src == "img/bulletwhite.png") { document.images['bullet1'].src = "img/bullet.png"; document.images['bullet2'].src = "img/bulletwhite.png"; } animate("next",false); },diff*options.speed+options.pause); } options.auto means that its automatically cycling, dir is the direction of the motion and clicked is whether or not the user clicked it. Is there something wrong with my syntax here? I ran firebug with it, and it doesn't throw any errors, it simply won't work. Any advice would help! I should mention that the src of bullet1 starts at bulletwhite.png and then I was hoping for it to change to bullet.png and have bullet2 change to bulletwhite.png.

    Read the article

  • How can I superimpose modified loess lines on a ggplot2 qplot?

    - by briandk
    Background Right now, I'm creating a multiple-predictor linear model and generating diagnostic plots to assess regression assumptions. (It's for a multiple regression analysis stats class that I'm loving at the moment :-) My textbook (Cohen, Cohen, West, and Aiken 2003) recommends plotting each predictor against the residuals to make sure that: The residuals don't systematically covary with the predictor The residuals are homoscedastic with respect to each predictor in the model On point (2), my textbook has this to say: Some statistical packages allow the analyst to plot lowess fit lines at the mean of the residuals (0-line), 1 standard deviation above the mean, and 1 standard deviation below the mean of the residuals....In the present case {their example}, the two lines {mean + 1sd and mean - 1sd} remain roughly parallel to the lowess {0} line, consistent with the interpretation that the variance of the residuals does not change as a function of X. (p. 131) How can I modify loess lines? I know how to generate a scatterplot with a "0-line,": # First, I'll make a simple linear model and get its diagnostic stats library(ggplot2) data(cars) mod <- fortify(lm(speed ~ dist, data = cars)) attach(mod) str(mod) # Now I want to make sure the residuals are homoscedastic qplot (x = dist, y = .resid, data = mod) + geom_smooth(se = FALSE) # "se = FALSE" Removes the standard error bands But does anyone know how I can use ggplot2 and qplot to generate plots where the 0-line, "mean + 1sd" AND "mean - 1sd" lines would be superimposed? Is that a weird/complex question to be asking?

    Read the article

  • Safe to pass objects to C functions when working in JNI Invocation API?

    - by bubbadoughball
    I am coding up something using the JNI Invocation API. A C program starts up a JVM and makes calls into it. The JNIenv pointer is global to the C file. I have numerous C functions which need to perform the same operation on a given class of jobject. So I wrote helper functions which take a jobject and process it, returning the needed data (a C data type...for example, an int status value). Is it safe to write C helper functions and pass jobjects to them as arguments? i.e. (a simple example - designed to illustrate the question): int getStatusValue(jobject jStatus) { return (*jenv)->CallIntMethod(jenv,jStatus,statusMethod); } int function1() { int status; jobject aObj = (*jenv)->NewObject (jenv, aDefinedClass, aDefinedCtor); jobject j = (*jenv)->CallObjectMethod (jenv, aObj, aDefinedObjGetMethod) status = getStatusValue(j); (*jenv)->DeleteLocalRef(jenv,aObj); (*jenv)->DeleteLocalRef(jenv,j); return status; } Thanks.

    Read the article

  • String Length Evaluating Incorrectly

    - by Justin R.
    My coworker and I are debugging an issue in a WCF service he's working on where a string's length isn't being evaluated correctly. He is running this method to unit test a method in his WCF service: // Unit test method public void RemoveAppGroupTest() { string addGroup = "TestGroup"; string status = string.Empty; string message = string.Empty; appActiveDirectoryServicesClient.RemoveAppGroup("AOD", addGroup, ref status, ref message); } // Inside the WCF service [OperationBehavior(Impersonation = ImpersonationOption.Required)] public void RemoveAppGroup(string AppName, string GroupName, ref string Status, ref string Message) { string accessOnDemandDomain = "MyDomain"; RemoveAppGroupFromDomain(AppName, accessOnDemandDomain, GroupName, ref Status, ref Message); } public AppActiveDirectoryDomain(string AppName, string DomainName) { if (string.IsNullOrEmpty(AppName)) { throw new ArgumentNullException("AppName", "You must specify an application name"); } } We tried to step into the .NET source code to see what value string.IsNullOrEmpty was receiving, but the IDE printed this message when we attempted to evaluate the variable: 'Cannot obtain value of local or argument 'value' as it is not available at this instruction pointer, possibly because it has been optimized away.' (None of the projects involved have optimizations enabled). So, we decided to try explicitly setting the value of the variable inside the method itself, immediately before the length check -- but that didn't help. // Lets try this again. public AppActiveDirectoryDomain(string AppName, string DomainName) { // Explicitly set the value for testing purposes. AppName = "AOD"; if (AppName == null) { throw new ArgumentNullException("AppName", "You must specify an application name"); } if (AppName.Length == 0) { // This exception gets thrown, even though it obviously isn't a zero length string. throw new ArgumentNullException("AppName", "You must specify an application name"); } } We're really pulling our hair out on this one. Has anyone else experienced behavior like this? Any tips on debugging it?

    Read the article

  • Why do compiled Haskell libraries see invalid static FFI storage?

    - by John Millikin
    I am using GHC 6.12.1, in Ubuntu 10.04 When I try to use the FFI syntax for static storage, only modules running in interpreted mode (ie GHCI) work properly. Compiled modules have invalid pointers, and do not work. I'd like to know whether anybody can reproduce the problem, whether this an error in my code or GHC, and (if the latter) whether it's a known issue. Given the following three modules: -- A.hs {-# LANGUAGE ForeignFunctionInterface #-} module A where import Foreign import Foreign.C foreign import ccall "&sys_siglist" siglist_a :: Ptr CString -- -- B.hs {-# LANGUAGE ForeignFunctionInterface #-} module B where import Foreign import Foreign.C foreign import ccall "&sys_siglist" siglist_b :: Ptr CString -- -- Main.hs {-# LANGUAGE ForeignFunctionInterface #-} module Main where import Foreign import Foreign.C import A import B foreign import ccall "&sys_siglist" siglist_main :: Ptr CString main = do putStrLn $ "siglist_a = " ++ show siglist_a putStrLn $ "siglist_b = " ++ show siglist_b putStrLn $ "siglist_main = " ++ show siglist_main peekSiglist "a " siglist_a peekSiglist "b " siglist_b peekSiglist "main" siglist_main peekSiglist name siglist = do ptr <- peekElemOff siglist 2 str <- maybePeek peekCString ptr putStrLn $ "siglist_" ++ name ++ "[2] = " ++ show str I would expect something like this output, where all pointer values identical and valid: $ runhaskell Main.hs siglist_a = 0x00007f53a948fe00 siglist_b = 0x00007f53a948fe00 siglist_main = 0x00007f53a948fe00 siglist_a [2] = Just "Interrupt" siglist_b [2] = Just "Interrupt" siglist_main[2] = Just "Interrupt" However, if I compile A.hs (with ghc -c A.hs), then the output changes to: $ runhaskell Main.hs siglist_a = 0x0000000040378918 siglist_b = 0x00007fe7c029ce00 siglist_main = 0x00007fe7c029ce00 siglist_a [2] = Nothing siglist_b [2] = Just "Interrupt" siglist_main[2] = Just "Interrupt"

    Read the article

  • Using Interface Builder efficiently

    - by Aaron Wetzler
    I am new to iPhone and objective c. I have spent hours and hours and hours reading documents and trying to understand how things work. I have RTFM or at least am in the process. My main problem is that I want to understand how to specify where an event gets passed to and the only way I have been able to do it is by specifying delegates but I am certain there is an easier/quicker way in IB. So, an example. Lets say I have 20 different views and view controllers and one MyAppDelegate. I want to be able to build all of these different Xib files in IB and add however many buttons and text fields and whatever and then specify that they all produce some event in the MyAppDelegate object. To do this I added a MyAppDelegate object in each view controller in IB's list view. Then I created an IBAction method in MyAppDelegate in XCode and went back to IB and linked all of the events to the MyAppDelegate object in each Xib file. However when I tried running it it just crashed with a bad read exception. My guess is that each Xib file is putting a MyAppDelegate object pointer that has nothing to do with the eventual MyAppDelegate adress that will actually be created at runtime. So my question is...how can I do this?!!!

    Read the article

  • MS Query Analizer/Management Studio replacement?

    - by kprobst
    I've been using SQL Server since version 6.5 and I've always been a bit amazed at the fact that the tools seem to be targeted to DBAs rather than developers. I liked the simplicity and speed of the Query Analizer for example, but hated the built-in editor, which was really no better than a syntax coloring-capable Notepad. Now that we have Management Studio the management part seems a bit better but from a developer standpoint the tools is even worse. Visual Studio's excellent text editor... without a way to customize keyboard bindings!? Don't get me started on how unusable is the tree-based management hierarchy. Why can't I re-root the tree on a list of stored procs for example the way the Enterprise Manager used to allow? Now I have a treeview that needs to be scrolled horizontally, which makes it eminently useless. The SQL server support in Visual Studio is fantastic for working with stored procedures and functions, but it's terrible as a general ad hoc data query tool. I've tried various tools over the years but invariably they seem to focus on the management side and shortchange the developer in me. I just want something with basic admin capabilities, good keyboard support and requisite DDL functionality (ideally something like the Query Analyzer). At this point I'm seriously thinking of using vim+sqlcmd and a console... I'm that desperate :) Those of you who work day in and day out with SQL Server and Visual Studio... do you find the tools to be adequate? Have you ever wished they were better and if you have found something better, could you share please? Thanks!

    Read the article

  • Very weird C file-handling anomaly

    - by KáGé
    Hello, I got a very weird issue that I cant figure out in my school project, which is the simulation of a simple filesystem in a human-readable textfile. Unfortunately I don't yet have enough time to translate the comments in my code or make it less gibberish, so if you are bothered by that, you don't have to help, I understand. See the code HERE. Now in drive.h, at line 574 is this part: i = getline(); #ifdef DEBUG printf("Free space in all found at %d.\n\n", i); if(drive.disk != NULL){ printf("Disk OK\n\n"); } #endif //write in data state = seekline(i); Before this it finds place for the allocation database entry in the ALL sector (see the "image files" in the mounts folder, this issue was tested on mount_30.efs-dbf), then gets the line with i = getline() fine (getline is in lglobal.h, line 39), but after that any file manipulation (in this case seekline's fseek, but if I comment that out, then the first fprintf after that) crashes the program straight away. I think the file gets somehow corrupted (though the Disk OK message appears) but can't figure out how. I've tried putting i = getline(); into comment, but it didn't make any difference. I've also tried asking at local programming forums but they didn't really help either. The last few lines of the output before it crashes: Dir written. (drive.h line 562) Seekline entered: 268 (called at drive.h line 564) Getline entered. (called at drive.h line 574) Line got: 268. Free space in all found at 268. (drive.h line 576) Seekline entered: 268 (called at drive.h line 582, note that this exact call was run successfully less than 20 lines back. This one should set the pointer to the beginning of the line it is currently in) After this it crashes. Does anyone has any idea of what causes this and how could I fix it? Thank you.

    Read the article

  • Cant' cast a class with multiple inheritance

    - by Jay S.
    I am trying to refactor some code while leaving existing functionality in tact. I'm having trouble casting a pointer to an object into a base interface and then getting the derived class out later. The program uses a factory object to create instances of these objects in certain cases. Here are some examples of the classes I'm working with. // This is the one I'm working with now that is causing all the trouble. // Some, but not all methods in NewAbstract and OldAbstract overlap, so I // used virtual inheritance. class MyObject : virtual public NewAbstract, virtual public OldAbstract { ... } // This is what it looked like before class MyObject : public OldAbstract { ... } // This is an example of most other classes that use the base interface class NormalObject : public ISerializable // The two abstract classes. They inherit from the same object. class NewAbstract : public ISerializable { ... } class OldAbstract : public ISerializable { ... } // A factory object used to create instances of ISerializable objects. template<class T> class Factory { public: ... virtual ISerializable* createObject() const { return static_cast<ISerializable*>(new T()); // current factory code } ... } This question has good information on what the different types of casting do, but it's not helping me figure out this situation. Using static_cast and regular casting give me error C2594: 'static_cast': ambiguous conversions from 'MyObject *' to 'ISerializable *'. Using dynamic_cast causes createObject() to return NULL. The NormalObject style classes and the old version of MyObject work with the existing static_cast in the factory. Is there a way to make this cast work? It seems like it should be possible.

    Read the article

  • How can I SETF an element in a tree by an accessor?

    - by Willi Ballenthin
    We've been using Lisp in my AI course. The assignments I've received have involved searching and generating tree-like structures. For each assignment, I've ended up writing something like: (defun initial-state () (list 0 ; score nil ; children 0 ; value 0)) ; something else and building my functions around these "states", which are really just nested lists with some loosely defined structure. To make the structure more rigid, I've tried to write accessors, such as: (defun state-score ( state ) (nth 2 state)) This works for reading the value (which should be all I need to do in a nicely functional world. However, as time crunches, and I start to madly hack, sometimes I want a mutable structure). I don't seem to be able to SETF the returned ...thing (place? value? pointer?). I get an error with something like: (setf (state-score *state*) 10) Sometimes I seem to have a little more luck writing the accessor/mutator as a macro: (defmacro state-score ( state ) `(nth 2 ,state)) However I don't know why this should be a macro, so I certainly shouldn't write it as a macro (except that sometimes it works. Programming by coincidence is bad). What is an appropriate strategy to build up such structures? More importantly, where can I learn about whats going on here (what operations affect the memory in what way)?

    Read the article

  • MsSql Server high Resource Waits and Head Blocker

    - by MartinHN
    Hi I have a MS SQL Server 2008 Standard installation running a database for a webshop. The current size of the database is 2.5 GB. Running on Windows 2008 Standard. Dual Intel Xeon X5355 @ 2.00 GHz. 4 GB RAM. When I open the Activity Monitor, I see that I have a Wait Time (ms/sec) of 5000 in the "Other" category. In the Processes list, all connections from the webshop, the Head Blocker value is 1. I see every day that when I try to access the website, it can take 20-30 secs before it even starts to "work". I know that it is not network latency. (I have a 301 redirect from the same server that is executed instantly). When the first request has been served, it seems as if it's not a sleep anymore and every subsequent request is served instantly with the speed of light. The problem was worse two weeks ago, until I changed every query to include WITH (NOLOCK). But I still experience the problem, and the Wait times in the Activity Monitor is about the same. The largest table (Images) has 32764 rows (448576 KB). Some tables exceed 300000 rows, thought they're much smaller in size than the Images table. I have the default clustered index for every primary key column, only. Any ideas?

    Read the article

  • Using forward declarations for build in datatypes.

    - by bdhar
    I understand that wherever possible we shall use forward declarations instead of includes to speed up the compilation. I have a class Person like this. #pragma once #include <string> class Person { public: Person(std::string name, int age); std::string GetName(void) const; int GetAge(void) const; private: std::string _name; int _age; }; and a class Student like this #pragma once #include <string> class Person; class Student { public: Student(std::string name, int age, int level = 0); Student(const Person& person); std::string GetName(void) const; int GetAge(void) const; int GetLevel(void) const; private: std::string _name; int _age; int _level; }; In Student.h, I have a forward declaration class Person; to use Person in my conversion constructor. Fine. But I have done #include <string> to avoid compilation error while using std::string in the code. How to use forward declaration here to avoid the compilation error? Is it possible? Thanks.

    Read the article

  • Is it wise to use temporary tables?

    - by Industrial
    Hi guys, We have a mySQL database table for products. We are utilizing a cache layer to reduce database load, but we think that it's a good idea to minimize the actual data needed to be stored in the cache layer to speed up the application further. All the products in the database, that is visible to visitors have a price attached to them: The prices are stored in a different table, called prices . There are multiple price categories depending on which discount level each visitor (customer) applies to. From time to time, there are campaigns which means that a special price for each product is available. The special prices are stored in a table called specials. Is it a bad to make a temp table that binds the tables together? It would only have the neccessary information and would ofcourse be cached. -------------|-------------|------------ | productId | hasPrice | hasSpecial -------------|-------------|------------ 1 | 1 | 0 2 | 1 | 1 By doing such, it would be super easy to know if the specific product really has a price, without having to iterate through the complete prices or specials table each time a product should be listed or presented. Are temp tables a common thing for web applications or is it just bad design?

    Read the article

  • Switching to WPF, the best use of time at Visual Studio Launch 2010

    - by Stewbob
    Yes, this is a programming-related question, if a little indirectly (that's why I marked it Community Wiki right away). For better or worse, I am switching from Winforms to WPF in April. I am also going to be in attendance at the Visual Studio Launch in Las Vegas. I have a real need to get up to speed quickly in WPF, so my question is: What sessions are going to be the best use of my time? I've got some picked out already, but I'm looking for some more advice on how to wade through all the marketing fluff and get some real educational value out of these few days. I have not been to one of these events before, so I don't really know how much is marketing hype, and how much is solid content. A couple of the workshops look interesting (VPR02 and VPS02), but I don't know enough about the actual content of these to justify the extra expense right now. Any thoughts there would be appreciated. And yes, I do have WPF learning planned other than just these few days in Vegas, but since I'm going to be there anyway, I want to learn as much as I can in the time available.

    Read the article

  • pass a number value to a Timer, XML and AS3

    - by VideoDnd
    I want to pass a number value to a Timer. How do I do this? My number and integer values for other variables work fine. Error I get null object reference and coercion of value, because I'm not passing to 'timer' properly. I don't want to say my variable's a number, I want to say it has a number value. Variable //what I have now var timer:Timer; timer = new Timer(100); Path myXML.COUNT.text(); XML <?xml version="1.0" encoding="utf-8"?> <SESSION> <TIMER TITLE="speed">100</TIMER> </SESSION> Parse and Load //LOAD XML var myXML:XML; var myLoader:URLLoader = new URLLoader(); myLoader.load(new URLRequest("time.xml")); myLoader.addEventListener(Event.COMPLETE, processXML); //PARSE XML function processXML(e:Event):void { myXML = new XML(e.target.data);

    Read the article

  • Submit button not focused even though tabindex is properly set

    - by Nicsoft
    Hello, I have defined tabindex for the input fields in a form. When tabbing through the input fields the submit button is never getting the focus, some other input fields in a different form on the page gets the focus. Those are all having tabindexes higher than 3. How come? <form action="subscription.php" name="subscribe" method="post" onsubmit="return isValidEmailAndEqual()"> <p id="formlabel">E-mail</p> <input type="text" name="email1" tabindex=1> <br/> <p id="formlabel">Repeat e-mail</p> <input type="text" name="email2" tabindex=2> <br/> <input id="inputsubmit" type="submit" value="Subscribe" tabindex=3> </form> .css: input { background-color : #333; border: 1px solid #EEE; color: #EEE; margin-bottom: 6px; margin-top: 4px; padding: 1px; width : 200px; } #inputsubmit { background-color : #d7e6f1; border: 1px solid #EEE; color: #0000ff; margin-bottom: 6px; margin-top: 4px; padding: 1px; width : 200px; } #inputsubmit:hover { cursor: pointer; cursor: hand; background-color : #d7e6f1; border: 1px solid #0000ff; color: #0000ff; margin-bottom: 6px; margin-top: 4px; padding: 1px; width : 200px; } p#formlabel{ width: 100; } Thanks in advance!

    Read the article

  • jQuery e.target bubbling best practice ?

    - by olouv
    In my heavy-ajax code, i always bind "click" the body tag & act depending on $(e.target) & using $.fn.hasClass(). However when i click on an anchor that has a </span> tag inside, my $(e.target) equals this node, and not the parent anchor as i would like it to. From now on, i have used this trick (var $t = $(e.target);) : /** bubbling **/ if($t.get(0).tagName !== "A" && $t.get(0).tagName !== "AREA") { $t = $t.parent("a"); if(empty($t)) return true; //else console.log("$t.bubble()", $t); } It feels wrong somehow... Do you have any better implementation ? $.fn.live() does not solve my issue as it still returns the span as the target. Moreover i'm looking for speed (running on atom-based touch devices) & live appeared to be way slower (twice) : http://jsperf.com/bind-vs-click/3 In fact, as @Guffa pointed, using $.fn.live() solves the span bubbling issue as i don't need the event.target anymore. I guess there is no other "right" answer here (using bind).

    Read the article

  • Working with complex objects in Prevayler commands

    - by alexantd
    The demos included in the Prevayler distribution show how to pass in a couple strings (or something simple like that) into a command constructor in order to create or update an object. The problem is that I have an object called MyObject that has a lot of fields. If I had to pass all of them into the CreateMyObject command manually, it would be a pain. So an alternative I thought of is to pass my business object itself into the command, but to hang onto a clone of it (keeping in mind that I can't store the BO directly in the command). Of course after executing this command, I would need to make sure to dispose of the original copy that I passed in. public class CreateMyObject implements TransactionWithQuery { private MyObject object; public CreateMyObject(MyObject business_obj) { this.object = (MyObject) business_obj.clone(); } public Object executeAndQuery(...) throws Exception { ... } } The Prevayler wiki says: Transactions can't carry direct object references (pointers) to business objects. This has become known as the baptism problem because it's a common beginner pitfall. Direct object references don't work because once a transaction has been serialized to the journal and then deserialized for execution its object references no longer refer to the intended objects - - any objects they may have referred to at first will have been copied by the serialization process! Therefore, a transaction must carry some kind of string or numeric identifiers for any objects it wants to refer to, and it must look up the objects when it is executed. I think by cloning the passed-in object I will be getting around the "direct object pointer" problem, but I still don't know whether or not this is a good idea...

    Read the article

  • Serializing QGraphicsScene contents

    - by Rob
    I am using the Qt QGraphicsScene class, adding pre-defined items such as QGraphicsRectItem, QGraphicsLineItem, etc. and I want to serialize the scene contents to disk. However, the base QGraphicsItem class (that the other items I use derive from) doesn't support serialization so I need to roll my own code. The problem is that all access to these objects is via a base QGraphicsItem pointer, so the serialization code I have is horrible: QGraphicsScene* scene = new QGraphicsScene; scene->addRect(QRectF(0, 0, 100, 100)); scene->addLine(QLineF(0, 0, 100, 100)); ... QList<QGraphicsItem*> list = scene->items(); foreach (QGraphicsItem* item, items) { if (item->type() == QGraphicsRectItem::Type) { QGraphicsRectItem* rect = qgraphicsitem_cast<QGraphicsRectItem*>(item); // Access QGraphicsRectItem members here } else if (item->type() == QGraphicsLineItem::Type) { QGraphicsLineItem* line = qgraphicsitem_cast<QGraphicsLineItem*>(item); // Access QGraphicsLineItem members here } ... } This is not good code IMHO. So, instead I could create an ABC class like this: class Item { public: virtual void serialize(QDataStream& strm, int version) = 0; }; class Rect : public QGraphicsRectItem, public Item { public: void serialize(QDataStream& strm, int version) { // Serialize this object } ... }; I can then add Rect objects using QGraphicsScene::addItem(new Rect(,,,)); But this doesn't really help me as the following will crash: QList<QGraphicsItem*> list = scene->items(); foreach (QGraphicsItem* item, items) { Item* myitem = reinterpret_class<Item*>(item); myitem->serialize(...) // FAIL } Any way I can make this work?

    Read the article

  • Passing Derived Class Instances as void* to Generic Callbacks in C++

    - by Matthew Iselin
    This is a bit of an involved problem, so I'll do the best I can to explain what's going on. If I miss something, please tell me so I can clarify. We have a callback system where on one side a module or application provides a "Service" and clients can perform actions with this Service (A very rudimentary IPC, basically). For future reference let's say we have some definitions like so: typedef int (*callback)(void*); // This is NOT in our code, but makes explaining easier. installCallback(string serviceName, callback cb); // Really handled by a proper management system sendMessage(string serviceName, void* arg); // arg = value to pass to callback This works fine for basic types such as structs or builtins. We have an MI structure a bit like this: Device <- Disk <- MyDiskProvider class Disk : public virtual Device class MyDiskProvider : public Disk The provider may be anything from a hardware driver to a bit of glue that handles disk images. The point is that classes inherit Disk. We have a "service" which is to be notified of all new Disks in the system, and this is where things unravel: void diskHandler(void *p) { Disk *pDisk = reinterpret_cast<Disk*>(p); // Uh oh! // Remainder is not important } SomeDiskProvider::initialise() { // Probe hardware, whatever... // Tell the disk system we're here! sendMessage("disk-handler", reinterpret_cast<void*>(this)); // Uh oh! } The problem is, SomeDiskProvider inherits Disk, but the callback handler can't receive that type (as the callback function pointer must be generic). Could RTTI and templates help here? Any suggestions would be greatly appreciated.

    Read the article

  • Poor performance using RMI-proxies with Swing components

    - by Patrick
    I'm having huge performance issues when I add RMI proxy references to a Java Swing JList-component. I'm retrieving a list of user Profiles with RMI from a server. The retrieval itself takes just a second or so, so that's acceptable under the circumstances. However, when I try to add these proxies to a JList, with the help of a custom ListModel and a CellRenderer, it takes between 30-60 seconds to add about 180 objects. Since it is a list of users' names, it's preferrable to present them alphabetically. The biggest performance hit is when I sort the elements as they get added to the ListModel. Since the list will always be sorted, I opted to use the built-in Collections.binarySearch() to find the correct position for the next element to be added, and the comparator uses two methods that are defined by the Profile interface, namely getFirstName() and getLastName(). Is there any way to speed this process up, or am I simply implementing it the wrong way? Or is this a "feature" of RMI? I'd really love to be able to cache some of the data of the remote objects locally, to minimize the remote method calls.

    Read the article

  • VSC++, virtual method at bad adress, curious bug

    - by antoon.groenewoud
    Hello, This guy: virtual phTreeClass* GetTreeClass() const { return (phTreeClass*)m_entity_class; } When called, crashed the program with an access violation, even after a full recompile. All member functions and virtual member functions had correct memory adresses (I hovered mouse over the methods in debug mode), but this function had a bad memory adress: 0xfffffffc. Everything looked okay: the 'this' pointer, and everything works fine up until this function call. This function is also pretty old and I didn't change it for a long time. The problem just suddenly popped up after some work, which I commented all out to see what was doing it, without any success. So I removed the virtual, compiled, and it works fine. I add virtual, compiled, and it still works fine! I basically changed nothing, and remember that I did do a full recompile earlier, and still had the error back then. I wasn't able to reproduce the problem. But now it is back. I didn't change anything. Removing virtual fixes the problem. Sincerely, Antoon

    Read the article

< Previous Page | 328 329 330 331 332 333 334 335 336 337 338 339  | Next Page >