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  • Constant NSDictionary/NSArray for class methods.

    - by Jeff B
    I am trying to code a global lookup table of sorts. I have game data that is stored in character/string format in a plist, but which needs to be in integer/id format when it is loaded. For instance, in the level data file, a "p" means player. In the game code a player is represented as the integer 1. This let's me do some bitwise operations, etc. I am simplifying greatly here, but trying to get the point across. Also, there is a conversion to coordinates for the sprite on a sprite sheet. Right now this string-integer, integer-string, integer-coordinate, etc. conversion is taking place in several places in code using a case statement. This stinks, of course, and I would rather do it with a dictionary lookup. I created a class called levelInfo, and want to define the dictionary for this conversion, and then class methods to call when I need to do a conversion, or otherwise deal with level data. NSString *levelObjects = @"empty,player,object,thing,doohickey"; int levelIDs[] = [0,1,2,4,8]; // etc etc @implementation LevelInfo +(int) crateIDfromChar: (char) crateChar { int idx = [[crateTypes componentsSeparatedByString:@","] indexOfObject: crateChar]; return levelIDs[idx]; } +(NSString *) crateStringFromID: (int) crateID { return [[crateTypes componentsSeparatedByString:@","] objectAtIndex: crateID]; } @end Is there a better way to do this? It feels wrong to basically build these temporary arrays, or dictionaries, or whatever for each call to do this translation. And I don't know of a way to declare a constant NSArray or NSDictionary. Please, tell me a better way....

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  • drawing different quartz 2d

    - by Cosizzle
    Hello, I'm trying to make a small application or demo thats a tab bar application. Each bar item loads in a new view. I've created a quartzView class that is called on by the controller: - (void)viewDidLoad { quartzView *drawingView = [[quartzView alloc] initWithFrame:CGRectMake(0,0,320,480)]; [self.view addSubview:drawingView]; [super viewDidLoad]; } From my understanding, the drawRect method must be triggered in order to render the object and to draw it. This is my quartzView class: #import "quartzView.h" @implementation quartzView #pragma mark shapes // Blue Circle - (void)drawRect:(CGRect)rect { NSLog(@"Trying to draw..."); CGContextRef ctx = UIGraphicsGetCurrentContext(); //get the current context CGContextClearRect(ctx, rect); //clear off the screen //draw a red square CGContextSetRGBFillColor(ctx, 255, 0, 0, 1); CGContextFillRect(ctx, CGRectMake(10, 10, 50, 50)); } // ==================================================================================================== #pragma mark - - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { // Initialization code } return self; } - (void)dealloc { [super dealloc]; } @end So how would I go about to say, if the view is view one, draw a square if it's view two draw a circle. And so on.

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  • Problems compiling peazip on OSX

    - by Yansky
    I'm having some problems with compiling Peazip on OSX (10.6). I emailed the Peazip developer and he said he probably couldn't help me too much as the error seems to be OSX specific and he doesn't have access to an OSX machine any more. The compiler I'm using is Lazarus as the source is in Pascal. The actual compile process seems to go ok, but when I run the peazip.app program launcher, I get the following error: http://img.photobucket.com/albums/v215/thegooddale/Screen-shot-2010-05-22-at-71907-PM.png Here is the app launcher that the compile made: http://forboden.com/coding/peazip.app.zip - you can use an unzip program to look at the files inside (i.e. unzip it twice). I also tried just running the peazip unix file executable that was produced after the compile from the terminal and I got this: http://img.photobucket.com/albums/v215/thegooddale/Screen-shot-2010-05-22-at-72148-PM.png Here are the messages from the compile log from Lazarus while compiling Peazip: http://pastebin.com/qK4bdncL (I asked on the Lazarus forums and they said I can just ignore those "ld: warning: unknown stabs type" warnings). Here is the info from the project_peach.compiled file: <?xml version="1.0"?> <CONFIG> <Compiler Value="/usr/local/bin/ppc386" Date="1238949773"/> <Params Value=" -MObjFPC -Sgi -O1 -gl -k-framework -kCarbon -k-framework -kOpenGL -k'-dylib_file' -k'/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib:/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib' -WG -vewnhi -l -Fu/Users/yansky/Desktop/peazip-3.1.src/res/themes/crystalc/ -Fu/Developer/lazarus/components/synedit/units/i386-darwin/ -Fu/Developer/lazarus/ideintf/units/i386-darwin/ -Fu/Developer/lazarus/lcl/units/i386-darwin/ -Fu/Developer/lazarus/lcl/units/i386-darwin/carbon/ -Fu/Developer/lazarus/packager/units/i386-darwin/ -Fu/Users/yansky/Desktop/peazip-3.1.src/ -Fu. -opeazip -dLCL -dLCLcarbon project_peach.lpr"/> </CONFIG> I guess there's little chance that anyone here has experience with Pascal and Lazarus since it's not that popular a language and the compiler is still in beta, but I thought I would post here in the hopes that someone might point me in the right general direction about where/how the peazip.app launcher is breaking.

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  • problem with addressfilter in WCF

    - by Zé Carlos
    I've build my own WCF channel with all necessary stuff (like encoders, bindings, etc) to use it with ServiceHost. I just want to build the "channel stack" making no custumizations at "Service Model". To acomplish this, my encoder returns perfect ServiceModel.Messages with a XML infoset just like other channel does. Lets assume the following service implementation: [ServiceContract(Namespace = "http://MyNS")] public interface IService1 { [OperationContract(IsOneWay = true)] void dummy(); } public class Service1 : IService1 { public void dummy() { Console.WriteLine("In Service1:dummy()"); } } I used this service through other bindings and traced the following ServiceModel.Message contents (SOAP format): <s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope" xmlns:a="http://www.w3.org/2005/08/addressing"> <s:Header> <a:Action s:mustUnderstand="1">http://MyNS/IService1/dummy</a:Action> <a:To s:mustUnderstand="1">amqp://localhost</a:To> </s:Header> <s:Body> <dummy xmlns="http://MyNS"></dummy> </s:Body> </s:Envelope> Then (just to debug) i changed my encoder to allways return this message. When i use my custom channel the WCF's runtime replay with an faul message telling: "The message with To '' cannot be processed at the receiver, due to an AddressFilter mismatch at the EndpointDispatcher. Check that the sender and receiver's EndpointAddresses agree." I read that the default EndPointDispatcher.AddressFilter simply looks to the "TO" header and delivery the message to corresponding service. This is happening with other bindings, why not happens with my custom channel too? Is there any way to i check what default AddressFilter is doing? Thanks

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  • Is it possible to create a custom, animated MKAnnotationView?

    - by smountcastle
    I'm trying to simulate the user location animation in MapKit (where-by the user's position is represented by a pulsating blue dot). I've created a custom subclass of MKAnnotationView and in the drawRect method I'm attempting to cycle through a set of colors. Here's a simpler implementation of what I'm doing: - (void)drawRect:(CGRect)rect { float magSquared = event.magnitude * event.magnitude; CGContextRef context = UIGraphicsGetCurrentContext(); if (idx == -1) { r[0] = 1.0; r[1] = 0.5; r[2] = 0; b[0] = 0; b[1] = 1.0; b[2] = 0.5; g[0] = 0.5; g[1] = 0; g[2] = 1.0; idx = 0; } // CGContextSetRGBFillColor(context, 1.0, 1.0 - magSquared * 0.015, 0.211, .6); CGContextSetRGBFillColor(context, r[idx], g[idx], b[idx], 0.75); CGContextFillEllipseInRect(context, rect); idx++; if (idx > 3) idx = 0; } Unfortunately this just causes the annotations to be one of the 3 different colors and doesn't cycle through them. Is there a way to force the MKAnnotations to continually redraw so that it appears to be animated?

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  • Threading best practice when using SFTP in C#

    - by Christian
    Ok, this is more one of these "conceptual questions", but I hope I got some pointers in the right direction. First the desired scenario: I want to query an SFTP server for directory and file lists I want to upload or download files simulaneously Both things are pretty easy using a SFTP class provided by Tamir.SharpSsh, but if I only use one thread, it is kind of slow. Especially the recursion into subdirs gets very "UI blocking", because we are talking about 10.000 of directories. My basic approach is simple, create some kind of "pool" where I keep 10 open SFTP connections. Then query the first worker for a list of dirs. If this list was obtained, send the next free workers (e.g. 1-10, first one is also free again) to get the subdirectory details. As soon as there is a worker free, send him for the subsubdirs. And so on... I know the ThreadPool, simple Threads and did some Tests. What confuses me a little bit is the following: I basically need... A list of threads I create, say 10 Connect all threads to the server If a connection drops, create a new thread / sftp client If there is work to do, take the first free thread and handle the work I am currently not sure about the implementation details, especially the "work to do" and the "maintain list of threads" parts. Is it a good idea to: Enclose the work in an object, containing a job description (path) and a callback Send the threads into an infinite loop with 100ms wait to wait for work If SFTP is dead, either revive it, or kill the whole thread and create a new one How to encapsulate this, do I write my own "10ThreadsManager" or are there some out Ok, so far... Btw, I could also use PRISM events and commands, but I think the problem is unrelated. Perhaps the EventModel to signal a done processing of a "work package"... Thanks for any ideas, critic.. Chris

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  • Property being immediately reset by ApplicationSetting Property Binding

    - by Slider345
    I have a .net 2.0 windows application written in c#, which currently uses several project settings to store user configurations. The forms in the application are made up of lots of user controls, each of which have properties that need to be set to these project settings. Right now these settings are manually assigned to the user control properties. I was hoping to simplify the code by replacing the manual implementation with ApplicationSettings Property Bindings. However, my first property is not behaving properly at all. The setting is an integer, used to record a port number typed into a text box. The setting is bound to an integer property on a user control, and that property sets the Text property on a TextBox control. When I type a new value into the textbox at runtime, as soon as the textbox loses focus, it is immediately replaced by the original value. A breakpoint on the property shows that it is immediately setting the property to the setting from the properties collection after I set it. Can anyone see what I'm doing wrong? Here's some code: The setting: [global::System.Configuration.UserScopedSettingAttribute()] [global::System.Diagnostics.DebuggerNonUserCodeAttribute()] [global::System.Configuration.DefaultSettingValueAttribute("1000")] public int Port { get{ return ((int)(this["Port"])); } set{ this["Port"] = value; } } The binding: this.ctrlNetworkConfig.DataBindings.Add(new System.Windows.Forms.Binding("PortNumber", global::TestProject.Properties.Settings.Default, "Port", true, System.Windows.Forms.DataSourceUpdateMode.OnPropertyChanged)); this.ctrlNetworkConfig.PortNumber = global::TestProject.Properties.Settings.Default.Port; And lastly, the property on the user control: public int PortNumber { get{ int port; if(int.TryParse(this.txtPortNumber.Text, out port)) return port; else return 0; } set{ txtPortNumber.Text = value.ToString(); } } Any thoughts? Thanks in advance for your help. EDIT: Sorry about the formatting, trying to correct.

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  • Implicit conversion : const reference vs non-const reference vs non-reference

    - by Nawaz
    Consider this code, struct A {}; struct B { B(const A&) {} }; void f(B) { cout << "f()"<<endl; } void g(A &a) { cout << "g()" <<endl; f(a); //a is implicitly converted into B. } int main() { A a; g(a); } This compiles fine, runs fine. But if I change f(B) to f(B&), it doesn't compile. If I write f(const B&), it again compiles fine, runs fine. Why is the reason and rationale? Summary: void f(B); //okay void f(B&); //error void f(const B&); //okay I would like to hear reasons, rationale and reference(s) from the language specification, for each of these cases. Of course, the function signatures themselves are not incorrect. Rather A implicitly converts into B and const B&, but not into B&, and that causes the compilation error.

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  • How to secure Add child record functionality in MVC on Parent's view?

    - by RSolberg
    I'm trying to avoid some potential security issues as I expose some a new set of functionality into the real world. This is basically functionality that will allow for a new comment to be added via a partialview on the "Parent" page. My comment needs to know a couple of things, first what record is the comment for and secondly who is making the comment. I really don't like using a hidden field to store the ID for the Parent record in the add comment form as that can be easily changed with some DOM mods. How should I handle this? PARENT <% Html.RenderPartial("AddComment", Model.Comments); %> CHILD <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<CommentsViewModel>" %> <% using (Html.BeginForm("AddComment", "Requests")) {%> <fieldset> <legend>New Comment</legend> <%= Html.HiddenFor(p => p.RequestID) %> <%= Html.TextBoxFor(p => p.Text) %> &nbsp; <input type="submit" value="Add" /> </fieldset> <% } %> CONTROLLER [AcceptVerbs(HttpVerbs.Post)] public void AddComment(CommentsViewModel commentsModel) { var user = GetCurrentUser(); commentsModel.CreatedByID = user.UserID; RequestsService.AddComment(commentsModel); }

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  • maintaining a large list in python

    - by Oren
    I need to maintain a large list of python pickleable objects that will quickly execute the following algorithm: The list will have 4 pointers and can: Read\Write each of the 4 pointed nodes Insert new nodes before the pointed nodes Increase a pointer by 1 Pop nodes from the beginning of the list (without overlapping the pointers) Add nodes at the end of the list The list can be very large (300-400 MB), so it shouldnt be contained in the RAM. The nodes are small (100-200 bytes) but can contain various types of data. The most efficient way it can be done, in my opinion, is to implement some paging-mechanism. On the harddrive there will be some database of a linked-list of pages where in every moment up to 5 of them are loaded in the memory. On insertion, if some max-page-size was reached, the page will be splitted to 2 small pages, and on pointer increment, if a pointer is increased beyond its loaded page, the following page will be loaded instead. This is a good solution, but I don't have the time to write it, especially if I want to make it generic and implement all the python-list features. Using a SQL tables is not good either, since I'll need to implement a complex index-key mechanism. I tried ZODB and zc.blist, which implement a BTree based list that can be stored in a ZODB database file, but I don't know how to configure it so the above features will run in reasonable time. I don't need all the multi-threading\transactioning features. No one else will touch the database-file except for my single-thread program. Can anyone explain me how to configure the ZODB\zc.blist so the above features will run fast, or show me a different large-list implementation?

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  • Bouncycastle encryption algorithms not provided

    - by David Read
    I'm trying to use BouncyCastle with android to implement ECDH and EL Gamal. I've added the bouncycastle jar file (bcprov-jdk16-144.jar) and written some code that works with my computers jvm however when I try and port it to my android application it throws: java.security.NoSuchAlgorithmException: KeyPairGenerator ECDH implementation not found A sample of the code is: Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider()); java.security.KeyPairGenerator keyGen = org.bouncycastle.jce.provider.asymmetric.ec.KeyPairGenerator.getInstance("ECDH", "BC"); ECGenParameterSpec ecSpec = new ECGenParameterSpec("prime192v1"); keyGen.initialize(ecSpec, SecureRandom.getInstance("SHA1PRNG")); KeyPair pair = keyGen.generateKeyPair(); PublicKey pubk = pair.getPublic(); PrivateKey prik = pair.getPrivate(); I then wrote a simple program to see what encryption algorithms are available and ran it on my android emulator and on my computers jvm the code was: Set<Provider.Service> rar = new org.bouncycastle.jce.provider.BouncyCastleProvider().getServices(); Iterator<Provider.Service> ir = rar.iterator(); while(ir.hasNext()) System.out.println(ir.next().getAlgorithm()); On android I do not get any of the EC algorithms while ran normally on my computer it's fine. I'm also getting the following two errors when compiling for a lot of the bouncy castle classes: 01-07 17:17:42.548: INFO/dalvikvm(1054): DexOpt: not resolving ambiguous class 'Lorg/bouncycastle/asn1/ASN1Encodable;' 01-07 17:17:42.548: DEBUG/dalvikvm(1054): DexOpt: not verifying 'Lorg/bouncycastle/asn1/ess/OtherSigningCertificate;': multiple definitions What am I doing wrong?

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  • Explicit behavior with checks vs. implicit behavior

    - by Silviu
    I'm not sure how to construct the question but I'm interested to know what do you guys think of the following situations and which one would you prefer. We're working at a client-server application with winforms. And we have a control that has some fields automatically calculated upon filling another field. So we're having a field currency which when filled by the user would determine an automatic filling of another field, maybe more fields. When the user fills the currency field, a Currency object would be retrieved from a cache based on the string introduced by the user. If entered currency is not found in the cache a null reference is returned by the cache object. Further down when asking the application layer to compute the other fields based on the currency, given a null currency a null specific field would be returned. This way the default, implicit behavior is to clear all fields. Which is the expected behavior. What i would call the explicit implementation would be to verify that the Currency object is null in which case the depending fields are cleared explicitly. I think that the latter version is more clear, less error prone and more testable. But it implies a form of redundancy. The former version is not as clear and it implies a certain behavior from the application layer which is not expressed in the tests. Maybe in the lower layer tests but when the need arises to modify the lower layers, so that given a null currency something else should be returned, i don't think a test that says just that without a motivation is going to be an impediment for introducing a bug in upper layers. What do you guys think?

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  • Nested Routes and Parameters for Rails URLs (Best Practice)

    - by viatropos
    Hey there, I have a decent understanding of RESTful urls and all the theory behind not nesting urls, but I'm still not quite sure how this looks in an enterprise application, like something like Amazon, StackOverflow, or Google... Google has urls like this: http://code.google.com/apis/ajax/ http://code.google.com/apis/maps/documentation/staticmaps/ https://www.google.com/calendar/render?tab=mc Amazon like this: http://www.amazon.com/books-used-books-textbooks/b/ref=sa_menu_bo0?ie=UTF8&node=283155&pf_rd_p=328655101&pf_rd_s=left-nav-1&pf_rd_t=101&pf_rd_i=507846&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1PK4ZKN4YWJJ9B86ANC9 http://www.amazon.com/Ruby-Programming-Language-David-Flanagan/dp/0596516177/ref=sr_1_1?ie=UTF8&s=books&qid=1258755625&sr=1-1 And StackOverflow like this: http://stackoverflow.com/users/169992/viatropos http://stackoverflow.com/questions/tagged/html http://stackoverflow.com/questions/tagged?tagnames=html&sort=newest&pagesize=15 So my question is, what is best practice in terms of creating urls for systems like these? When do you start storing parameters in the url, when don't you? These big companies don't seem to be following the rules so hotly debated in the ruby community (that you should almost never nest URLs for example), so I'm wondering how you go about implementing your own urls in larger scale projects because it seems like the idea of not nesting urls breaks down at anything larger than a blog. Any tips?

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  • Comparing objects with IDispatch to get main frame only (BHO)

    - by shaimagz
    I don't know if anyone familiar with BHO (Browser Helper Object), but an expert in c++ can help me too. In my BHO I want to run the OnDocumentComplete() function only on the main frame - the first container and not all the Iframes inside the current page. (an alternative is to put some code only when this is the main frame). I can't find how to track when is it the main frame that being populated. After searching in google I found out that each frame has "IDispatch* pDisp", and I have to compare it with a pointer to the first one. This is the main function: STDMETHODIMP Browsarity::SetSite(IUnknown* pUnkSite) { if (pUnkSite != NULL) { // Cache the pointer to IWebBrowser2. HRESULT hr = pUnkSite->QueryInterface(IID_IWebBrowser2, (void **)&m_spWebBrowser); if (SUCCEEDED(hr)) { // Register to sink events from DWebBrowserEvents2. hr = DispEventAdvise(m_spWebBrowser); if (SUCCEEDED(hr)) { m_fAdvised = TRUE; } } } else { // Unregister event sink. if (m_fAdvised) { DispEventUnadvise(m_spWebBrowser); m_fAdvised = FALSE; } // Release cached pointers and other resources here. m_spWebBrowser.Release(); } // Call base class implementation. return IObjectWithSiteImpl<Browsarity>::SetSite(pUnkSite); } This is where I want to be aware whether its the main window(frame) or not: void STDMETHODCALLTYPE Browsarity::OnDocumentComplete(IDispatch *pDisp, VARIANT *pvarURL) { // as you can see, this function get the IDispatch *pDisp which is unique to every frame. //some code } I asked this question on Microsoft forum and I got an answer without explaining how to actually implement that: http://social.msdn.microsoft.com/Forums/en-US/ieextensiondevelopment/thread/7c433bfa-30d7-42db-980a-70e62640184c

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  • How do I get google protocol buffer messages over a socket connection without disconnecting the clie

    - by Dan
    Hi there, I'm attempting to send a .proto message from an iPhone application to a Java server via a socket connection. However so far I'm running into an issue when it comes to the server receiving the data; it only seems to process it after the client connection has been terminated. This points to me that the data is getting sent, but the server is keeping its inputstream open and waiting for more data. Would anyone know how I might go about solving this? The current code (or at least the relevant parts) is as follows: iPhone: Person *person = [[[[Person builder] setId:1] setName:@"Bob"] build]; RequestWrapper *request = [[[RequestWrapper builder] setPerson:person] build]; NSData *data = [request data]; AsyncSocket *socket = [[AsyncSocket alloc] initWithDelegate:self]; if (![socket connectToHost:@"192.168.0.6" onPort:6666 error:nil]){ [self updateLabel:@"Problem connecting to socket!"]; } else { [self updateLabel:@"Sending data to server..."]; [socket writeData:data withTimeout:-1 tag:0]; [self updateLabel:@"Data sent, disconnecting"]; //[socket disconnect]; } Java: try { RequestWrapper wrapper = RequestWrapper.parseFrom(socket.getInputStream()); Person person = wrapper.getPerson(); if (person != null) { System.out.println("Persons name is " + person.getName()); socket.close(); } On running this, it seems to hang on the line where the RequestWrapper is processing the inputStream. I did try replacing the socket writedata method with [request writeToOutputStream:[socket getCFWriteStream]]; Which I thought might work, however I get an error claiming that the "Protocol message contained an invalid tag (zero)". I'm fairly certain that it doesn't contain an invalid tag as the message works when sending it via the writedata method. Any help on the matter would be greatly appreciated! Cheers! Dan (EDIT: I should mention, I am using the metasyntactic gpb code; and the cocoaasyncsocket implementation)

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  • Javascript Post Request like a Form Submit

    - by Joseph Holsten
    I'm trying to direct a browser to a different page. If I wanted a GET request, I might say document.location.href = 'http://example.com/q=a'; But the resource I'm trying to access won't respond properly unless I use a POST request. If this were not dynamically generated, I might use the HTML <form action="http://example.com/" method="POST"> <input type="hidden" name="q" value="a"> </form> Then I would just submit the form from the DOM. But really I would like JavaScript that allows me to say post_to_url('http://example.com/', {'q':'a'}); What's the best cross browser implementation? Edit I'm sorry I was not clear. I need a solution that changes the location of the browser, just like submitting a form. If this is possible with XMLHTTPRequest, it is not obvious. And this should not be asynchronous, nor use XML, so AJAX is not the answer.

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  • Python coding test problem for interviews

    - by Kal
    I'm trying to come up with a good coding problem to ask interview candidates to solve with Python. They'll have an hour to work on the problem, with an IDE and access to documentation (we don't care what people have memorized). I'm not looking for a tough algorithmic problem - there are other sections of the interview where we do that kind of thing. The point of this section is to sit and watch them actually write code. So it should be something that makes them use just the data structures which are the everyday tools of the application developer - lists, hashtables (dictionaries in Python), etc, to solve a quasi-realistic task. They shouldn't be blocked completely if they can't think of something really clever. We have a problem which we use for Java coding tests, which involves reading a file and doing a little processing on the contents. It works well with candidates who are familiar with Java (or even C++). But we're running into a number of candidates who just don't know Java or C++ or C# or anything like that, but do know Python or Ruby. Which shouldn't exclude them, but leaves us with a dilemma: On the one hand, we don't learn much from watching someone struggle with the basics of a totally unfamiliar language. On the other hand, the problem we use for Java turns out to be pretty trivial in Python (or Ruby, etc) - anyone halfway competent can do it in 15 minutes. So, I'm trying to come up with something better. Surprisingly, Google doesn't show me anyone doing something like this, unless I'm just too dumb to enter the obvious search term. The best idea I've come up with involves scheduling workers to time slots, but it's maybe a little too open-ended. Have you run into a good example? Or a bad one? Or do you just have an idea?

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  • Hidden features of Perl?

    - by Adam Bellaire
    What are some really useful but esoteric language features in Perl that you've actually been able to employ to do useful work? Guidelines: Try to limit answers to the Perl core and not CPAN Please give an example and a short description Hidden Features also found in other languages' Hidden Features: (These are all from Corion's answer) C# Duff's Device Portability and Standardness Quotes for whitespace delimited lists and strings Aliasable namespaces Java Static Initalizers JavaScript Functions are First Class citizens Block scope and closure Calling methods and accessors indirectly through a variable Ruby Defining methods through code PHP Pervasive online documentation Magic methods Symbolic references Python One line value swapping Ability to replace even core functions with your own functionality Other Hidden Features: Operators: The bool quasi-operator The flip-flop operator Also used for list construction The ++ and unary - operators work on strings The repetition operator The spaceship operator The || operator (and // operator) to select from a set of choices The diamond operator Special cases of the m// operator The tilde-tilde "operator" Quoting constructs: The qw operator Letters can be used as quote delimiters in q{}-like constructs Quoting mechanisms Syntax and Names: There can be a space after a sigil You can give subs numeric names with symbolic references Legal trailing commas Grouped Integer Literals hash slices Populating keys of a hash from an array Modules, Pragmas, and command-line options: use strict and use warnings Taint checking Esoteric use of -n and -p CPAN overload::constant IO::Handle module Safe compartments Attributes Variables: Autovivification The $[ variable tie Dynamic Scoping Variable swapping with a single statement Loops and flow control: Magic goto for on a single variable continue clause Desperation mode Regular expressions: The \G anchor (?{}) and '(??{})` in regexes Other features: The debugger Special code blocks such as BEGIN, CHECK, and END The DATA block New Block Operations Source Filters Signal Hooks map (twice) Wrapping built-in functions The eof function The dbmopen function Turning warnings into errors Other tricks, and meta-answers: cat files, decompressing gzips if needed Perl Tips See Also: Hidden features of C Hidden features of C# Hidden features of C++ Hidden features of Java Hidden features of JavaScript Hidden features of Ruby Hidden features of PHP Hidden features of Python

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  • help in the Donalds B. Johnson's algorithm, i cannot understand the pseudo code (PART II)

    - by Pitelk
    Hi all , i cannot understand a certain part of the paper published by Donald Johnson about finding cycles (Circuits) in a graph. More specific i cannot understand what is the matrix Ak which is mentioned in the following line of the pseudo code : Ak:=adjacency structure of strong component K with least vertex in subgraph of G induced by {s,s+1,....n}; to make things worse some lines after is mentins " for i in Vk do " without declaring what the Vk is... As far i have understand we have the following: 1) in general, a strong component is a sub-graph of a graph, in which for every node of this sub-graph there is a path to any node of the sub-graph (in other words you can access any node of the sub-graph from any other node of the sub-graph) 2) a sub-graph induced by a list of nodes is a graph containing all these nodes plus all the edges connecting these nodes. in paper the mathematical definition is " F is a subgraph of G induced by W if W is subset of V and F = (W,{u,y)|u,y in W and (u,y) in E)}) where u,y are edges , E is the set of all the edges in the graph, W is a set of nodes. 3)in the code implementation the nodes are named by integer numbers 1 ... n. 4) I suspect that the Vk is the set of nodes of the strong component K. now to the question. Lets say we have a graph G= (V,E) with V = {1,2,3,4,5,6,7,8,9} which it can be divided into 3 strong components the SC1 = {1,4,7,8} SC2= {2,3,9} SC3 = {5,6} (and their edges) Can anybody give me an example for s =1, s= 2, s= 5 what if going to be the Vk and Ak according to the code? The pseudo code is in my previous question in http://stackoverflow.com/questions/2908575/help-in-the-donalds-b-johnsons-algorithm-i-cannot-understand-the-pseudo-code and the paper can be found at http://stackoverflow.com/questions/2908575/help-in-the-donalds-b-johnsons-algorithm-i-cannot-understand-the-pseudo-code thank you in advance

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  • Good grammar for date data type for recursive descent parser LL(1)

    - by Totophil
    I'm building a custom expression parser and evaluator for production enviroment to provide a limited DSL to the users. The parser itself as the DSL, need to be simple. The parser is going to be built in an exotic language that doesn't support dynamic expression parsing nor has any parser generator tools available. My decision is to go for recursive descent approach with LL(1) grammar, so that even programmers with no previous experience in evaluating expression could quickly learn how the code works. It has to handle mixed expressions made up of several data types: decimals, percentages, strings and dates. And dates in the format of dd/mm/yyyy are easy to confuse with a string of devision ops. Is where a good solution to this problem? My own solution that is aimed at keeping the parser simple involves prefixing dates with a special symbol, let's say apostrophe: <date> ::= <apostr><digit><digit>/<digit><digit>/<digit><digit><digit><digit> <apostr> ::= ' <digit> ::= '0'..'9'

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  • Need Advice on building the database. all in one table or split?

    - by Ibrahim Azhar Armar
    hello, i am developing an application for a real-estate company. the problem i am facing is about implementing the database. however i am just confused on which way to adopt i would appreciate if you could help me out in reasoning the database implementation. here is my situation. a) i have to store the property details in the database. b) the properties have approximately 4-5 categories to which it will belong for ex : resedential, commnercial, industrial etc. c) now the categories have sub-categories. for example. a residential category will have sub category such as. Apartment / Independent House / Villa / Farm House/ Studio Apartment etc. and hence same way commercial and industrial or agricultural will too have sub-categories. d) each sub-categories will have to store the different values. like a resident will have features like Bedrooms/ kitchens / Hall / bathroom etc. the features depends on the sub categories. for an example on how i would want to implement my application you can have a look at this site. http://www.magicbricks.com/bricks/postProperty.html i could possibly think of the solution like this. a) create four to five tables depending upon the categories which will be existing(the problem is categories might increase in the future). b) create different tables for all the features, location, price, description and merge the common property table into one. for example all the property will have the common entity such as location, total area, etc. what would you advice for me given the current situation. thank you

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  • CQRS - The query side

    - by mattcodes
    A lot of the blogsphere articles related to CQRS (command query repsonsibility) seperation seem to imply that all screens/viewmodels are flat. e.g. Name, Age, Location Of Birth etc.. and thus the suggestion that implementation wise we stick them into fast read source etc.. single table per view mySQL etc.. and pull them out with something like primitive SqlDataReader, kick that nasty nhibernate ORM etc.. However, whilst I agree that domain models dont mapped well to most screens, many of the screens that I work with are more dimensional, and Im sure this is pretty common in LOB apps. So my question is how are people handling screen where by for example it displays a summary of customer details and then a list of their orders with a [more detail] link etc.... I thought about keeping with the straight forward SQL query to the Query Database breaking off the outer join so can build a suitable ViewModel to View but it seems like overkill? Alternatively (this is starting to feel yuck) in CustomerSummaryView table have a text/big (whatever the type is in your DB) column called Orders, and the columns for the Order summary screen grid are seperated by , and rows by |. Even with XML datatype it still feeel dirty. Any thoughts on an optimal practice?

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  • x86 opcode alignment references and guidelines

    - by mrjoltcola
    I'm generating some opcodes dynamically in a JIT compiler and I'm looking for guidelines for opcode alignment. 1) I've read comments that briefly "recommend" alignment by adding nops after calls 2) I've also read about using nop for optimizing sequences for parallelism. 3) I've read that alignment of ops is good for "cache" performance Usually these comments don't give any supporting references. Its one thing to read a blog or a comment that says, "its a good idea to do such and such", but its another to actually write a compiler that implements specific op sequences and realize most material online, especially blogs, are not useful for practical application. So I'm a believer in finding things out myself (disassembly, etc. to see what real world apps do). This is one case where I need some outside info. I notice compilers will usually start an odd byte instruction immediately after whatever previous instruction sequence there was. So the compiler is not taking any special care in most cases. I see "nop" here or there, but usually it seems nop is used sparingly, if at all. How critical is opcode alignment? Can you provide references for cases that I can actually use for implementation? Thanks.

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  • Which Computer Organization & Architecture book is good for me?

    - by claws
    I'm always interested in learning the inner working of things. I started with C programming and then learnt Operating systems (from stallings) and then linkers & loaders and then assembly language after reading these now I want to go into little more depth. Computer Architecture. I feel that makes everything clear. As per SO archives these are the two good books: Computer Architecture: A Quantitative Approach, 4th Edition Computer Organization and Design, Fourth Edition, ~ David A. Patterson, John L. Hennessy But I've browsed through the contents of these books and found that they don't exactly meet my needs. I want to learn more about caches, Memory Management Unit , mapping b/w virtual memory & physical memory I'm no way interested in other ISAs like MIPS etc.. I'm IA32 and X86-64 fan and I want to stick to it. I'm not a hardware developer I don't want to details like circuit diagrams or How is L1, L2 & L3 caches are implemented? I want to know the parallel processing technologies like HyperThreading at the architecture level but again I don't want to design them. I liked the table of Contents of - Computer Architecture: A Quantitative Approach, 4th Edition but Quantitave Approach? Seriously?? I want to know the details of current technologies and I dont want to spend reading 200 pages of outdated old technologies ( I experienced this while learning ASM}

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  • Datetime Format Setting In SSRS

    - by Amit
    We have a requirement where date time values would be passed to the report parameter which is of "String" date type (and not "DateTime"). The report parameter would be a queried one i.e. it would have a list of values in which the passed value should fall in. The strange part is that if the date time value passed to this parameter is passed in this format mm/dd/yyyy hh:mm:ss AM/PM then only it succeeds otherwise a error is displayed (If month/date/hour/minute/second is having a single digit value then we need to pass single digit value to parameter as well). Assuming that the report server picks this format from the "regional settings" in control panel, we tried modifying the date & time formats as yyyy-mm-dd & HH:mm:ss but the outcome was the same. On researching more I found some suggestions specifying to change the language property in the rdl (I was not able to figure out how) but this would not be the solution I am looking for. I also found another topic here but it didn't provide the solution but it didn't provide the solution we are looking for. I need to understand on if this format is controlled by the report server & is it configurable. It would be great if someone can provide some guidance. Thanks.

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