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  • Double Negation in C++ code.

    - by Brian Gianforcaro
    I just came onto a project with a pretty huge code base. I'm mostly dealing with C++ and a lot of the code they write uses double negation for their boolean logic. if (!!variable && (!!api.lookup("some-string"))) { do_some_stuff(); } I know these guys are intelligent programmers, it's obvious they aren't doing this by accident. I'm no seasoned C++ expert, my only guess at why they are doing this is that they want to make absolutely positive that the value being evaluated is the actual boolean representation. So they negate it, then negate that again to get it back to its actual boolean value. Is this a correct? or am I missing something else? Thanks, Brian Gianforcaro

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  • radio button value in php

    - by Crash893
    Im trying to make a simple survey in php I have a set of radio buttons on a page called sja.php that sends its to sjamail.php page the problem is that when i go to get $answer = $_POST['ans']; I can't seen to do anything like echo "$answer"; but if i were to throw some logic at it like if ($answer == "ans1") { echo 'Correct'; } else { echo 'Incorrect'; } IT will display correct or incorrect so why is it i can't access the value of the radio button ans?

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  • Is enemy / bot A.I. part of the model or controller in an MVC game

    - by Iain
    It could be part of the model because it's part of the business logic of the game. It could be part of the controller because it could be seen as simulating player input, which would be considered part of the controller, right? Or would it? What about a normal enemy, like a goomba in Mario? UPDATE: Wow, that's really not the answer I was expecting. As far as I could tell, A.I. is an internal part of the autonomous game system, hence model. I'm still not convinced.

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  • 'script/console test' with spork and rspec not loading the whole environment?

    - by TheDeeno
    I'm trying to load up console to interact with some of my rspec mocking helpers. I expected that running script/console test would load an env similar to when I run spec. However, this doesn't appear to be the case. It looks like spec_helper is never loaded. Or, if it is, it's not actually running through the logic because spork has polluted it a bit. In short, is there a quick and easy way to get an interactive rspec party going?

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  • How does SQL Server treat statements inside stored procedures with respect to transactions?

    - by Sleepless
    Hi All! Say I have a stored procedure consisting of several seperate SELECT, INSERT, UPDATE and DELETE statements. There is no explicit BEGIN TRANS / COMMIT TRANS / ROLLBACK TRANS logic. How will SQL Server handle this stored procedure transaction-wise? Will there be an implicit connection for each statement? Or will there be one transaction for the stored procedure? Also, how could I have found this out on my own using T-SQL and / or SQL Server Management Studio? Thanks!

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  • Linq to SQL gives NotSupportedException when using local variables

    - by zwanz0r
    It appears to me that it matters whether you use a variable to temporary store an IQueryable or not. See the simplified example below: This works: List<string> jobNames = new List<string> { "ICT" }; var ictPeops = from p in dataContext.Persons where ( from j in dataContext.Jobs where jobNames.Contains(j.Name) select j.ID).Contains(p.JobID) select p; But when I use a variable to temporary store the subquery I get an exception: List<string> jobNames = new List<string> { "ICT" }; var jobs = from j in dataContext.Jobs where jobNames.Contains(j.Name) select j.ID; var ictPeops = from p in dataContext.Persons where jobs.Contains(p.JobID) select p; "System.NotSupportedException: Queries with local collections are not supported" I don't see what the problem is. Isn't this logic that is supposed to work in LINQ?

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  • Testing with Qt's QTestLib module

    - by ak
    Hi I started writing some tests with Qt's unit testing system. How do you usually organize the tests? It is one test class per one module class, or do you test the whole module with a single test class? Qt docs (or some podcast that I recently watched) suggested to follow the former strategy. I want to write tests for a module. The module provides only one class that is going to be used by the module user, but there is a lot of logic abstracted in other classes, which I would also like to test, besides testing the public class. The problem is that Qt's proposed way to run tests involved the QTEST_MAIN macro: QTEST_MAIN(TestClass) #include "test_class.moc" and eventually one test program is capable of testing just one test class. And it kinda sucks to create test projects for every single class in the module. Of course, one could take a look at the QTEST_MAIN macro, rewrite it, and run other test classes. But is there something, that works out of the box?

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  • Adding WCF service reference adds DataContract types too

    - by Avi Shilon
    Hi everybody, I've used Visual Studio's Add Service Reference feature to add a service (actually it is a workflow service, created in WF4 RC1, but I don't think this makes any difference), and it also added the DataContracts that the service uses. At first this seemed fine, because All I've had in the DataContracts was simply properties, with no implementations. But now I've added code in the constructor of one data contracts that initializes creates an instance of one of the properties that exposes a list of other DCs, and when I've updated the service reference via VS (2010 RC1), the implementation was not updated. What should I do? Should I use my DCs instead of the ones created by VS or should I use the ones VS created? I've noticed that the properties in the VS-generated DCs contain some additional logic for checking equality in the setters and they also implement some interfaces too (like IExtensibleDataObject and INotifyPropertyChanged) which might get handy I guess in the future (I'm not knowledgeable at WCF). Thank you for your time folks, Avi

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  • Linq to SQL Where clause based on field selected at runtime

    - by robasaurus
    I'm trying to create a simple reusable search using LINQ to SQL. I pass in a list of words entered in a search box. The results are then filtered based on this criteria. private IQueryable<User> BasicNameSearch(IQueryable<User> usersToSearch, ICollection<string> individualWordsFromSearch) { return usersToSearch .Where(user => individualWordsFromSearch.Contains(user.Forename.ToLower()) || individualWordsFromSearch.Contains(user.Surname.ToLower())); } Now I want this same search functionality on a different datasource and want to dynamically select the fields to apply the search to. For instance instead of IQueryable of Users I may have an IQueryable of Cars and instead of firstname and surname the search goes off Make and Model. Basically the goal is to reuse the search logic by dynamically selecting what to search on at runtime.

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  • Which design pattern should I be using?

    - by Gabriel
    Here's briefly what I'm trying to do. The user supplies me with a link to a photo from one of several photo-sharing websites (such as Flickr, Zooomr, et. al). I then do some processing on the photo using their respective APIs. Right now, I'm only implementing one service, but I will most likely add more in the near future. I don't want to have a bunch of if/else or switch statements to define the logic for the different websites (but maybe that's necessary?) I'd rather just call GetImage(url) and have it get me the image from whatever service the url's domain is from. I'm confused how the GetImage function and classes should be designed. Maybe I need the strategy pattern? I'm still reading and trying to understand the various design patterns and how I could make one fit in this case. I'm doing this in C#, but this question is language-agnostic.

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  • Can I make DataGridView.EndEdit trigger the CellValidating event?

    - by Don Kirkby
    I'm using a DataGridView in my WinForms application. My main objective is to make the Enter key not move to the next row in the grid. I still want the enter key to validate and end edit mode. I found this FAQ entry and subclassed DataGridView to override ProcessDialogKey(). If the key pressed is Enter, I call EndEdit(), otherwise I call base.ProcessDialogKey(). It works great, except the CellValidating event isn't fired. Currently, I'm just manually calling my validation logic before I call EndEdit, but it seems like I'm missing something. I guess I could call OnCellValidating, but then I'd be worried I'm missing some other event. What I really want is some flavour of EndEdit() that behaves just like pressing enter on the last row of a grid with adding disabled.

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  • Detecting/Repairing NSConnection failure

    - by anthony
    I would like to use NSConnection/NSDistributedObject for interprocess communication. I would like the client to be able to handle the case where the server is only occasionally reachable. How can I determine if sending a message to the NSConnection will fail or has failed? Currently if my server (the process that has vended the remote object) dies, the client will crash if it sends a selector to the remote object. Ideally I'd like to have a wrapper for the remote object that can lazily instantiate (or reinstantiate) the connection, and return a default value in the case where the connection could not be instantiated, or the connection has failed. I don't really know the correct way to do this using objective c. Here's some pseudocode representing this logic: if myConnection is null: instantiate myConnection if MyConnection is null: return defaultValue try return [myConnection someMethod] catch myConnection = null return defaultValue

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  • Build a JavaScript wrapper for a rails-generated XML API?

    - by Thor Thurn
    I am working with a large website written in Ruby on Rails. Thanks to the support for REST in Rails 2, the site's business logic is all accessible via a consistent XML API. Now I want to be able to easily write one or more JavaScript frontends to the site that interact with the generated Rails XML API. Ideally, an automated wrapper for the API could be created in JavaScript, since this would minimize the effort required in writing XML processing code for the more than 500 API functions. How, then, can I automatically generate a wrapper around a given XML API in JavaScript so that it's more pleasant to work with? I've worked with solutions of this nature for Java that generate classes and methods to wrap an API, so my current thinking is that I want something of that nature for JavaScript. I'd be open to an alternative take on the problem, though.

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  • How can I pipe a large amount of data as a runtime argument?

    - by Zombies
    Running an executable JAR on a linux platform here. The program it self works on a somewhat large amount of data, basically a list of URLs... could be up to 2k. Currently I get this from a simple DB call. But I was thinking that instead of creating a new mode and writing SQL to get a new result set and having to redploy everytime, I could just make the program more robust by passing in the result set (the list of URLs) that need to be worked on... so, within a linux environment, is there a pain-free/simple way to get the result set and pass it in dynamically? I know file i/o is one, but it doesn't seem to be effecient because each file has to be named, as well more logic to handle grabbing the correct file, creating a file with a unique name, etc.

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  • Recommend an algorithms exercise book?

    - by Parappa
    I have a little book called Problems on Algorithms by Ian Parberry which is chock full of exercises related to the study of algorithms. Can anybody recommend similar books? What I am not looking for are recommendations of good books related to algorithms or the theory of computation. Introduction to Algorithms is a good one, and of course there's the Knuth stuff. Ideally I want to know of any books that are light on instructional material and heavy on sample problems. In a nutshell, exercise books. Preferably dedicated to algorithms rather than general logic or other math problems. By the way, the Parberry book does not seem to be in print, but it is available as a PDF dowload.

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  • Watching setTimeout loops so that only one is running at a time.

    - by DA
    I'm creating a content rotator in jQuery. 5 items total. Item 1 fades in, pauses 10 seconds, fades out, then item 2 fades in. Repeat. Simple enough. Using setTimeout I can call a set of functions that create a loop and will repeat the process indefinitely. I now want to add the ability to interrupt this rotator at any time by clicking on a navigation element to jump directly to one of the content items. I originally started going down the path of pinging a variable constantly (say every half second) that would check to see if a navigation element was clicked and, if so, abandon the loop, then restart the loop based on the item that was clicked. The challenge I ran into was how to actually ping a variable via a timer. The solution is to dive into JavaScript closures...which are a little over my head but definitely something I need to delve into more. However, in the process of that, I came up with an alternative option that actually seems to be better performance-wise (theoretically, at least). I have a sample running here: http://jsbin.com/uxupi/14 (It's using console.log so have fireBug running) Sample script: $(document).ready(function(){ var loopCount = 0; $('p#hello').click(function(){ loopCount++; doThatThing(loopCount); }) function doThatOtherThing(currentLoopCount) { console.log('doThatOtherThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatThing(currentLoopCount)},5000) } } function doThatThing(currentLoopCount) { console.log('doThatThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatOtherThing(currentLoopCount)},5000); } } }) The logic being that every click of the trigger element will kick off the loop passing into itself a variable equal to the current value of the global variable. That variable gets passed back and forth between the functions in the loop. Each click of the trigger also increments the global variable so that subsequent calls of the loop have a unique local variable. Then, within the loop, before the next step of each loop is called, it checks to see if the variable it has still matches the global variable. If not, it knows that a new loop has already been activated so it just ends the existing loop. Thoughts on this? Valid solution? Better options? Caveats? Dangers? UPDATE: I'm using John's suggestion below via the clearTimeout option. However, I can't quite get it to work. The logic is as such: var slideNumber = 0; var timeout = null; function startLoop(slideNumber) { ...do stuff here to set up the slide based on slideNumber... slideFadeIn() } function continueCheck(){ if (timeout != null) { // cancel the scheduled task. clearTimeout(timeout); timeout = null; return false; }else{ return true; } }; function slideFadeIn() { if (continueCheck){ // a new loop hasn't been called yet so proceed... // fade in the LI $currentListItem.fadeIn(fade, function() { if(multipleFeatures){ timeout = setTimeout(slideFadeOut,display); } }); }; function slideFadeOut() { if (continueLoop){ // a new loop hasn't been called yet so proceed... slideNumber=slideNumber+1; if(slideNumber==features.length) { slideNumber = 0; }; timeout = setTimeout(function(){startLoop(slideNumber)},100); }; startLoop(slideNumber); The above kicks of the looping. I then have navigation items that, when clicked, I want the above loop to stop, then restart with a new beginning slide: $(myNav).click(function(){ clearTimeout(timeout); timeout = null; startLoop(thisItem); }) If I comment out 'startLoop...' from the click event, it, indeed, stops the initial loop. However, if I leave that last line in, it doesn't actually stop the initial loop. Why? What happens is that both loops seem to run in parallel for a period. So, when I click my navigation, clearTimeout is called, which clears it.

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  • Lua class instance with nested tables

    - by Anonnobody
    Hello, Simple lua game with simple class like so: creature = class({ name = "MONSTER BADDY!", stats = { power = 10, agility = 10, endurance = 10, filters = {} }, other_things = ... }) creatureA = creature.new() creatureB = creature.new() creatureA.name = "Frank" creatureB.name = "Zappa" creatureA.stats.agility = 20 creatureB.stats.power = 12 -- blah blah blah Non table values are individual to each instance, but table values are shared among all instances and if I modify a stats.X value in one instance, all other instances see the same stats table. Q1: Is my OO implementation flawed? I tried LOOP and the same result occured, is there a fundamental flaw in my logic? Q2: How would you have each instance of creature have it's own stats table (and sub tables)? PS. I cannot flatten my class table as it's a bit more complicated than the example and other parts of the code are simplified with this nested table implementation. Thanks a bunch.

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  • jquery jstree or dynatree parent node don't get selected

    - by mazhar
    I have used jquery jstree or dynatree using check boxes and found the same logic The thing is that the if for example there is a parent and 4 child. a) i select all the 4 child (parent get auto selected) the 4 child and the parent node id get posted to the controller. b) But if i select less then 4 children (parent get auto selected) only child node ids get posted to the controller. Is there any way even if i select less then 4 children all my selected nodes included the parent get posted to the controller?

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  • Where to place java applet policy file?

    - by makdere
    Hi all, I am working on an artificial intelligence project which is a logic game and aims two user connecting to the server on the network who acts as an Admin and then start to play one by one. In order to create connections, i have a server code which is just listening on localhost:8000 and assigning team values to the clients as they arrive. After connecting, clients make their move under Admin's control. The question is that when i try to put my code to work in the browser it fails with the following error: java.security.AccessControlException: access denied (java.net.SocketPermission 127.0.0.1:8000 connect,resolve) Even though i have created my own policy, first granting only Socket access permission to the codebase of my project folder (file:///home/xxx/projects/-), after it didnt work i granted all permissions from all codebase. I tried placing my policy file both in the home directory and in the same directory where my applet code resides. Appreciate any tips, thanks.

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  • Service Layer Patter - Could we avoid the service layer on a specific case?

    - by lidermin
    Hi, we are trying to implement an application using the Service Layer Pattern cause our application needs to connect to other multiple applications too, and googling on the web, we found this link of a demostrative graphic for the "right" way of apply the pattern: martinfowler.com - Service Layer Pattern But now we have a question: what if our system needs to implement some business logic, only for our application (like some maintenance data for the system itself) that we don't need to share with other systems. Based on this graphic: As it seems, it will be unnecesary to implement a service layer just for that; it will be more practical to avoid the service layer, and just go from User Interface to the Business Layer (for example). What should be the right way in this case to implement the Service Layer Pattern? What do you suggest us for a scenario like the one I told you? Thanks in advance.

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  • Service Layer Patter - Could we avoid the service layer on a specific case?

    - by lidermin
    Hi, we are trying to implement an application using the Service Layer Pattern cause our application needs to connect to other multiple applications too, and googling on the web, we found this link of a demostrative graphic for the "right" way of apply the pattern: martinfowler.com - Service Layer Pattern But now we have a question: what if our system needs to implement some business logic, only for our application (like some maintenance data for the system itself) that we don't need to share with other systems. Based on this graphic: As it seems, it will be unnecesary to implement a service layer just for that; it will be more practical to avoid the service layer, and just go from User Interface to the Business Layer (for example). What should be the right way in this case to implement the Service Layer Pattern? What do you suggest us for a scenario like the one I told you? Thanks in advance.

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  • displaying current minute of a soccer match

    - by zurna
    I could not figure out the logic I would need to display a current minute of a soccer match. I have three fields in the database. DateFirstStarted DateSecondStarted DateFullEnded I should enter DateFirstStarted when the game starts and on the website. i.e. game starts at 7:05pm, on 7:25pm it should display '20 on the website. However, it should stop on the 45th minute. Then, I enter DateSecondStarted when the second half starts and should count from 46 to 90 and freeze there. Do I make sense? How can I do it? Is there a better way to do this?

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  • abstract method signature, inheritance, and "Do" naming convention

    - by T. Webster
    I'm learning about design patterns and in examples of code I've seen a convention where the abstract class declares a method, for example: public abstract class ServiceBase { ... public virtual object GetSomething(); and then protected abstract object DoGetSomething(); My question is on why these two methods exist, since they appear to serve the same purpose. Is this so that the base class GetSomething() method logic cannot be overridden by inherited classes? But then again, the method is marked virtual, so it can be overridden anyway. What is the usefulness here in requiring derived class implementers to implement the abstract method when the virtual method can be called anyway?

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  • What causes a WPF ListCollectionView that uses custom sorting to re-sort its items?

    - by Drew Noakes
    Consider this code (type names genericised for the purposes of example): // Bound to ListBox.ItemsSource _items = new ObservableCollection<Item>(); // ...Items are added here ... // Specify custom IComparer for this collection view _itemsView = CollectionViewSource.GetDefaultView(_items) ((ListCollectionView)_itemsView).CustomSort = new ItemComparer(); When I set CustomSort, the collection is sorted as I expect. However I require the data to re-sort itself at runtime in response to the changing of the properties on Item. The Item class derives from INotifyPropertyChanged and I know that the property fires correctly as my data template updates the values on screen, only the sorting logic is not being called. I have also tried raising INotifyPropertyChanged.PropertyChanged passing an empty string, to see if a generic notification would cause the sorting to be initiated. No bananas. EDIT In response to Kent's suggestion I thought I'd point out that sorting the items using this has the same result, namely that the collection sorts once but does not re-sort as the data changes: _itemsView.SortDescriptions.Add( new SortDescription("PropertyName", ListSortDirection.Ascending));

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  • prevent _doPostBack getting rendered in button markup

    - by Christo Fur
    Hi Is it possible to prevent the _doPostBack() call getting rendered on a button? I would like add some custom logic prior to calling the postback. I have added an onClick event to the button e.g. <button id="manualSubmit" runat="server" class="manual-submit" onclick="$('#jeweller-form').hide();" /> However, this just gets rendered inline before the _doPostBack() But the postback gets fired before the jQueryHide takes place I would like to call my own JS function then manually trigger the postback any ideas?

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