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  • Avoid stuck calling callback

    - by andlomba
    Hello all, This is a question about generic c++ event driven applications design. Lets assume that we have two threads, a "Dispatcher" (or "Engine"...) and a "Listener" (or "Client"...). Let's assume that I write the Dispatcher code, and release it as a library. I also write the Listener interface, of course. When the Dispatcher executes (after Listener registration) listenerInstance.onSomeEvent(); the event handling code will actually be executed by the Dispatcher thread, so if the person that implements the Listener writes something like void Listener::onSomeEvent() { while(true) ; } The Dispatcher will stuck forever. Is there a "plain old c++" (I mean no boost or libsigc++) way to "decouple" the two classes, so I can be sure that my Dispatcher will work fine whatever the Listeners does in the callbacks? bye and thanks in advance, Andrea

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  • Adding new column in Sales Order View Items in Magento Admin

    - by fdierre
    In the admin interface of Magento I need to modify the tables in the Sales / Order / View order so that it shows, besides the products name, their manufacturer as well. I'm trying to look for the file to modify to make that happen. I thought I would find a section with all the columns that are displayed in app/code/core/Mage/Sales/Block/Order/Item/Renderer/Default.php but by inspecting it there seem to be no reference to the columns/product attributes. I also tried to modify app/design/adminhtml/default/default/template/sales/order/view/items/renderer/default.phtml by changing <?php echo $this->getColumnHtml($_item, 'name') ?> into <?php echo $this->getColumnHtml($_item, 'manufacturer') ?> but it changed nothing, so I suppose that file is not involved... Can anybody please point me to the right file to modify? Thank you!

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  • When accessing ResultSets in JDBC, is there an elegant way to distinguish between nulls and actual z

    - by Uri
    When using JDBC and accessing primitive types via a result set, is there a more elegant way to deal with the null/0 than the following: int myInt = rs.getInt(columnNumber) if(rs.wasNull())? { // Treat as null } else { // Treat as 0 } I personally cringe whenever I see this sort of code. I fail to see why ResultSet was not defined to return the boxed integer types (except, perhaps, performance) or at least provide both. Bonus points if anyone can convince me that the current API design is great :) My solution was to write a wrapper that returns an Integer (I care more about elegance of client code than performance), but I'm wondering if I'm missing a better way to do this.

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  • JavaScript inheritance extend function

    - by Zach
    I'm having some trouble understanding the IF clause at the end of this function from Pro JavaScript Design Patterns: function extend(subClass, superClass) { var F = function() {}; F.prototype = superClass.prototype; subClass.prototype = new F(); subClass.prototype.constructor = subClass; subClass.superclass = superClass.prototype; if(superClass.prototype.constructor == Object.prototype.constructor) { superClass.prototype.constructor = superClass; } } The book explains that these lines ensure that the superclass's constructor attribute is correctly set, even if the superclass is the Object class itself. Yet, if I omit those three lines and do the following: function SubClass() {}; extend(SubClass, Object); alert(Object.prototype.constructor == Object); The alert says 'true', which means the superclass's constructor is set correctly even without those last three lines. Under what conditions, then, does this IF statement do something useful? Thanks.

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  • What are the disadvantages of targeting the JVM instead of x86?

    - by Pindatjuh
    I'm developing a new language. My initial target was to compile to native x86 for the Windows platform, but now I am in doubt. I've seen some new languages target the JVM (most notable Scala and Clojure). Ofcourse it's not possible to port every language easily to the JVM; to do so may lead to small changes to the language and it's design. After posing this question, I even doubted more about this decision. I now know some "pro" JVM arguments. The original question was: is targetting the JVM a good idea, when creating a compiler for a new language? Updated the question: What are the disadvantages of targeting the JVM instead of x86 on Windows?

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  • How do I use an enum with custom values for a Sharepoint Web part?

    - by Jeff
    I'm trying to design a Web Part that has a drop-down list for the user to choose from. Eventually, these values will be automatically generated based on some kind of outside data source, so they're going to have somewhat arbitrary numeric values associated with them. This is the code I have now: public enum filterChoice { All=0, BOCC=12, Sustainability=15, Clerk=4, DA=13, Emergency=7, Highlights=3, POS=6, PR=1, PH=5, SHPR=2, Test=8, Transportation=14, Volunteer=16 }; These are different categories I want the user to choose from. When I choose one and save the settings for my Web Part, Sharepoint is only saving the values in numeric order; that is, All=0, BOCC=1, Sustainability=3 [...] so my Web Part then thinks the user chose the value with the corresponding number (PR when they chose BOCC, Highlights when they chose Sustainability, etc.) How can I make Sharepoint honor my custom values?

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  • DDD Infrastructure services

    - by Zygimantas
    Hello, I am learning DDD and I am a little bit lost in Infrastructure layer: As I understand, "all good DDD applications" should have 4 layers: Presentation, Application, Domain and Infrastructure. Database should be accessed using Repositories. Repository interfaces should be in Domain layer and repository implementation - in Infrastructure (reference http://stackoverflow.com/questions/693221/ddd-where-to-keep-domain-interfaces-the-infrastructure). Application, Domain and Infrastructure layer should/may have services (reference www.lostechies.com/blogs/jimmy_bogard/archive/2008/08/21/services-in-domain-driven-design.aspx), in example EmailService in Infrastructure layer which sends Email messages. BUT, inside Infrastructure layer we have repository implementations, which are used to access database. So, in this case, repositories are database services? What is the difference between Infrastructure service and repository? Thanks in advance!

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  • Netbeans or Eclipse for C++?

    - by Robert Gould
    I'm currently working on a pet project and need to do C++ development on Windows, Mac, Linux, and Solaris, and I've narrowed it down to Netbeans and Eclipse, so I was wonderig which is more solid as a C++ editor. I just need solid editing, good autocompletion for templated code ad external libraries, and project file management, the build tools are external, so thats irrelevant here, for my comparison. Thus which is a better choice? Note: I know I should be using emacs or vim, but the issue is, my theory at least, that I'm left handed, so I use my right side (design,creativity) of the brain more than the left side (logic, memory), so I just simply cannot use emacs or vim, my brain simply isn't compatible, I tried them many times too, even used emacs for a few months but it drove me crazy... Thanks

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  • Access is refusing to run an query with linked table?

    - by Mahmoud
    Hey all i have 3 tables each as follow cash_credit Bank_Name-------in_date-------Com_Id---Amount America Bank 15/05/2010 1 200 HSBC 17/05/2010 3 500 Cheque_credit Bank_Name-----Cheque_Number-----in_date-------Com_Id---Amount America Bank 74835435-5435 15/05/2010 2 600 HSBC 41415454-2851 17/05/2010 5 100 Companies com_id----Com_Name 1 Ebay 2 Google 3 Facebook 4 Amazon Companies table is a linked table when i tried to create an query as follow SELECT cash_credit.Amount, Companies.Com_Name, cheque_credit.Amount FROM cheque_credit INNER JOIN (cash_credit INNER JOIN Companies ON cash_credit.com_id = Companies.com_id) ON cheque_credit.com_id = Companies.com_id; I get an error saying that my inner Join is incorrectly, this query was created using Access 2007 query design the error is Type mismatch in expression then i thought it might be the inner join so i tried Left Join and i get an error that this method is not used JOIN expression is not supported I am confused on where is the problem that is causing all this

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  • Problematic comboBox Windows Forms

    - by zaidwaqi
    Hi, I use VS2008 C# + Windows Forms. I can't understand why comboBox does not behave the way it should. In Design mode, I added a comboBox to my form, and edit Items to add "A" and "B". Double-clicking brings me to SelectedIndexChanged event, which I edit to display the selected text with MessageBox. private void comboBoxImageSet_SelectedIndexChanged(object sender, EventArgs e) { MessageBox.Show(comboBoxImageSet.SelectedText); } When I run, and select "A" or "B" in the comboBox, the MessageBox appears, but nothing is written. Why? Thanks.

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  • C# similar technologies and books in Java

    - by MigNix
    Hi, I know this can look like dublicate of other discussions and I have already reviewed them, but they are different. I want to learn Java and I want to know are there any books similar to those that I have seen for C#. Here is the list: C# 4.0 in a Nutshell: The Definitive Reference Probably Java in a Nutshell :) Professional C# 4.0 and .NET 4 Pro C# 2010 and the .NET 4 Platform Accelerated C# 2010 Programming WCF Services Essential Windows Communication Foundation (WCF): For .NET Framework 3.5 C# in Depth: What you need to master C# 2 and 3 CLR via C# Professional ADO.NET 3.5 with LINQ and the Entity Framework Professional Enterprise .NET Framework Design Guidelines: Conventions, Idioms, and Patterns for Reusable .NET Libraries Mainly I am interested in Java 6 and want to know about JVM , Cuncurency, Data access and distributed application technologies. I have seen there are some books on JVM like Inside the Java 2 Virtual Machine also some free books on official web site. Also I found concurrent programming in Java. But may be you can suggest any others. Thank you

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  • Force an object to be allocated on the heap

    - by Warren Seine
    A C++ class I'm writing uses shared_from_this() to return a valid boost::shared_ptr<>. Besides, I don't want to manage memory for this kind of object. At the moment, I'm not restricting the way the user allocates the object, which causes an error if shared_from_this() is called on a stack-allocated object. I'd like to force the object to be allocated with new and managed by a smart pointer, no matter how the user declares it. I thought it could be done through a proxy or an overloaded new operator, but I can't find a proper way of doing that. Is there a common design pattern for such usage? If it's not possible, how can I test it at compile time?

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  • Field contains foreign IDs for different tables

    - by Rich
    I am developing a php/mysql driven facebook game. I am stuck on an element the table design. When a user completes a task I want to trigger any number of events. I was thinking of something like so: tbl_events *event_id - serogate primary ID *task_id - foreign ID of the task just completed *event_type - what type of event e.g is it a facebook stream publish or a message to the user or does it unlock a new element of the game? *event_param - this is where it gets tricky... the event parameter is a problem for two reasons, 1) it will contain different foreign ids... dependent on the event_type and thus it will not be possible to join to x table. Meaning I would have to call two queries. 2) Most events require a single id or text, however some events require multiple parameters - like the facebook stream publish.

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  • Creating a "Universities Attended" Profile field/block (Drupal)

    - by Frank0051
    Interesting question for everyone. So I have am thinking of adding a "university attended" field to the profile page of members in Drupal. I guess I am trying to figure out the best way to go about it. I was originally thinking of a text field, but than I thought you could get multiple instances of of university names, making it hard to sort people by school (ie. UF, University of Florida, Florida, U of F, etc). I then began to think about creating a drop down, but I wasn't quite sure where I could get a listing of all the schools. Perhaps I could find a database population that a site like LinkedIn or Facebook uses. Then I thought of what happens when someone has attended multiple schools, how would I account for that? So, I guess I wanted to pose the question of how would you go about adding a University(ies) attended field to profile pages if you had to design a site to do so?

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  • solutions for rapid front-end development?

    - by fayer
    im using mvc framework and i have learned some techniques that help me with different parts of RAD. models: doctrine/visual paradigm controllers/libraries: various design patterns now i only need to know what technique/solution i should use for the views so that i can create views more rapidly. cause i don't think it's efficient to code css/html manually, even though i understand it. its the same principle when using visual paradigm to create both my mysql database tables and doctrine model classes. i believe in using right tools will boost up development speed. so what could i use for the views to save time and energy and don't reinvent the wheel all the time? dreamweaver? any css generation tools? 960/blueprint for layout? suggestions? thanks

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  • Scraping html WITHOUT uniquie identifiers using python

    - by Nicholas Law
    I would like to design an algorithm using python that scrapes thousands of pages like this one and this one, gathers all the data and inserts it into a MySQL database. The script will be run on a weekly or bi-weekly basis to update the database of any new information added to each individual page. Ideally I would like a scraper that is easy to work with for table structured data but also data that does not have unique identifiers (ie. id and classes attributes). Which scraper add-on should I use? BeautifulSoup, Scrapy or Mechanize? Are there any particular tutorials/books I should be looking at for this desired result? In the long-run I will be implementing a mobile app that works with all this data through querying the database.

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  • Send Email in iphone

    - by user559080
    Hi, I am new to iphone. I am working on first app..I could design Email view by using Interface Builder. My requirement is, I have to add contact list. And choose required contact, when i clicked on To UIButton, It will be placed on Address textfield. Finally, I can click the send UIButton, the email reach it's destination. How can I do this? Can anyone explain it and send me proper code. Image link is: http://img266.imageshack.us/img266/6447/emailau.png Thanks in Advance.

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  • How to properly align textboxes on a webpage with labels

    - by Grant
    Hi, this is a CSS / design question. I have three textboxes that i want to be center aligned on a web page. Then i want a label description to the right of each one. When i use attribute like text:align:centre because the labels are of different length it throws out the aligment of the textboxes [see image link below] http://www.mediafire.com/imageview.php?quickkey=qcyoajm2iuk Is there an easy way of keeping the textboxes aligned and then have the labels off the to the right without changing the textboxes? Thanks.

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  • Is this SQL select code following good practice?

    - by acidzombie24
    I am using sqlite and will port to mysql (5) later. I wanted to know if I am doing something I shouldnt be doing. I tried purposely to design so I'll compare to 0 instead of 1 (I changed hasApproved to NotApproved to do this, not a big deal and I haven't written any code). I was told I never need to write a subquery but I do here. My Votes table is just id, ip, postid (I don't think I can write that subquery as a join instead?) and that's pretty much all that is on my mind. Naming conventions I don't really care about since the tables are created via reflection and is all over the place. select id, name, body, upvotes, downvotes, (select 1 from UpVotes where IPAddr=? AND post=Post.id) as myup, (select 1 from DownVotes where IPAddr=@0 AND post=Post.id) as mydown from Post where flag = '0' limit ?, ?"

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  • Microsoft Access - Enter Parameter Value why?

    - by Jane Doe
    I am encountering a problem for my database. Here is the relationships of the database And tried to do the query for how many transactions have movie "Harry_Potter"? so I used SQL query: SELECT COUNT(td.movie) AS number_of_occurrence, td.transaction_number FROM TransactionDetails td, MovieDetails md WHERE md.movie = Harry_Potter But it asks for Harry_Potter enter parameter value why? The relevant SQL statements are CREATE TABLE TransactionDetails ( transaction_number INTEGER PRIMARY KEY, movie VARCHAR(30) NOT NULL, date_of_transaction DATE NOT NULL, member_number INTEGER NOT NULL ) CREATE TABLE MovieDetails ( movie VARCHAR(30) PRIMARY KEY, movie_type VARCHAR(3) NOT NULL, movie_genre VARCHAR(10) NOT NULL ) ALTER TABLE TransactionDetails ADD CONSTRAINT member_number_fk FOREIGN KEY (member_number) REFERENCES LimelightMemberDetails(member_number); ALTER TABLE TransactionDetails ADD CONSTRAINT transaction_number_drink_fk FOREIGN KEY (transaction_number) REFERENCES DrinkTransactionDetails(transaction_number); ALTER TABLE TransactionDetails ADD CONSTRAINT transaction_number_food_fk FOREIGN KEY (transaction_number) REFERENCES FoodTransactionDetails(transaction_number); ALTER TABLE TransactionDetails ADD CONSTRAINT movie_fk FOREIGN KEY (movie) REFERENCES MovieDetails (movie); Thank you for your help! If there is anything wrong with my database design please let me know! thank you!

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  • Haskell: Constrain function on type Double to only work with Integers

    - by thurn
    Suppose I'm writing a function that takes a list of integers and returns only those integers in the list that are less than 5.2. I might do something like this: belowThreshold = filter (< 5.2) Easy enough, right? But now I want to constrain this function to only work with input lists of type [Int] for design reasons of my own. This seems like a reasonable request. Alas, no. A declaration that constraints the types as so: belowThreshold :: [Integer] -> [Integer] belowThreshold = filter (< 5.2) Causes a type error. So what's the story here? Why does doing filter (< 5.2) seem to convert my input list into Doubles? How can I make a version of this function that only accepts integer lists and only returns integer lists? Why does the type system hate me?

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  • What's the difference between Path and Polygon control? + issues when designing custom drawing user

    - by tomo
    I'm starting to design a custom control with rather complex drawing. It will be a kind of chart (a kind of radar chart). It will be composed of a few axises with labels, line-regions (like spider-network) and filled shapes. The main question is what's the difference between using Path control and Polygon control? What's better to use here? The goal is to prepare control with minimal amount of c# and try to do as much as possible in xaml / binding. The next important requirement is that control should resize to parent containers' width - if possible without any long recalulations in c#.

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  • Which programming paradigm or language open most your mind?

    - by Dom De Felice
    It is often said that some programming languages exist that once grasped can open your mind and change the way you write software. A sort of "software design enlightenment", we can say. I heard this about Lisp, Smalltalk, Haskell, pure functional programming in general.. What are your experiences about this? I know that the right language to use depends on your needs, but I would like to know the one that better improve your programming skills in general. What do you think would be the best language/paradigm to learn to end up being a better programmer in the long run?

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  • Saving data in a inherited django model

    - by aldeano
    I'm building an app to save data and some calculations made with those datas, the idea is keep the data in one model and the calculations in other. So, the models are like this: class FreshData(models.Model): name = models.CharField(max_length=20) one = models.IntegerField() two = models.IntegerField() def save(self, *args, **kwargs): Calculations() Calculations.three = self.one + self.two super(FreshData, self).save(*args, **kwargs) Calculations.save() class Calculations(FreshData): three = models.IntegerField() I've got a valueerror pointing out "self.one" and "self.two" as without value. I keep the idea in witch my design is wrong and django has a simpler way to store related data.

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  • What is the easiest straightforward way of telling which version performs better?

    - by Peter Perhác
    I have an application, which I have re-factored so that I believe it is now faster. One can't possibly feel the difference, but in theory, the application should run faster. Normally I would not care, but as this is part of my project for my master's degree, I would like to support my claim that the re-factoring did not only lead to improved design and 'higher quality', but also an increase in performance of the application (a small toy-thing - a train set simulation). I have toyed with the latest VisualVM thing today for about four hours but I couldn't get anything helpful out of it. There isn't (or I haven't found it) a way to simply compare the profiling results taken from the two versions (pre- and post- refactoring). What would be the easiest, the most straightforward way of simply telling the slower from the faster version of the application. The difference of the two must have had an impact on the performance. Thank you.

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