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  • Custom class deallocated as soon as the app starts.

    - by Tangrs
    Heya, I've added a class object to the nib file. All connections are made. But for some reason, the object is deallocated as soon as it's created. Here's the code: control.h: #import <Foundation/Foundation.h> @interface control : NSObject { IBOutlet UILabel *PlayerScore; } -(IBAction) addPoint: sender; -(void) dealloc; @end control.m: #import "control.h" @implementation control -(IBAction)addPoint: sender { NSLog(@"Ohhai. Didn't crash."); //Doesn't even make it to this stage. int i = [PlayerScore.text intValue]; PlayerScore.text=[NSString stringWithFormat: @"%d",++i]; } -(void) dealloc { NSLog(@"ZOMGWTF?"); [super dealloc]; } @end Here is the console log: [Session started at 2010-06-09 19:47:57 +1000.] 2010-06-09 19:47:58.771 App[91100:207] ZOMGWTF? And after I click the button which messages addPoint, of course, it crashes. 2010-06-09 19:47:59.703 App[91100:207] * -[control] performSelector:withObject:withObject:]: message sent to deallocated instance 0x3843d80 Does anyone have any ideas?

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  • Should I be backing up a webapp's data to another host continuously ?

    - by user196289
    I have webapp in development. I need to plan for what happens if the host goes down. I will lose some very recent session status (which I can live with) and everything else should be persistently stored in the database. If I am starting up again after an outage, can I expect a good host to reconstruct the database to within minutes of where I was up to ? Or seconds ? Or should I build in a background process to continually mirror the database elsewhere ? What is normal / sensible ? Obviously a good host will have RAID and other redundancy so the likelihood of total loss should be low, and if they have periodic backups I should lose only very recent stuff but this is presumably likely to be designed with almost static web content in mind, and my site is transactional with new data being filed continuously (with a customer expectation that I don't ever lose it). Any suggestions / advice ? Are there off the shelf frameworks for doing this ? (I'm primarily working in Java) And should I just plan to save the data or should I plan to have an alternative usable host implementation ready to launch in case the host doesn't come back up in a suitable timeframe ?

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  • Is `super` local variable?

    - by Michael
    // A : Parent @implementation A -(id) init { // change self here then return it } @end A A *a = [[A alloc] init]; a. Just wondering, if self is a local variable or global? If it's local then what is the point of self = [super init] in init? I can successfully define some local variable and use like this, why would I need to assign it to self. -(id) init { id tmp = [super init]; if(tmp != nil) { //do stuff } return tmp; } b. If [super init] returns some other object instance and I have to overwrite self then I will not be able to access A's methods any more, since it will be completely new object? Am I right? c. super and self pointing to the same memory and the major difference between them is method lookup order. Am I right? sorry, don't have Mac to try, learning theory as for now...

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  • Multisite Enabling a Table

    - by Joe Fitzgibbons
    I am creating a table (table A) that will have a number of columns(of course) and there will be another table (table B) that holds metadata associated to rows in table A. I am working with a multi site implementation that has one database for the whole shabang. Rows in table A could belong to any number of sites but must belong to at least one. The problem I have is I am not sure what the best practice is for defining what site each row in table A belongs to. I want performance and scalability. There is no finite number of sites going forward. Rows in table A could belong to any number of sites in the future. Right now there are only 3. My initial thoughts are to have a primary site ID in Table A and then metadata in table B will have rows defining additional sites as needed. Another thought is to have a column in Table A for each site and it is a boolean as to wether it belongs to that site. Lastly I have thought about having another table to map rows in Table A to each site. What is the best way to associate rows in a table with any number of sites with performance and scalability in mind?

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  • Email server; Is this method spam-safe?

    - by Camran
    I have a classifieds website, and on each classified there is a tip-form where users may tip a friend about the classified. The tip-forms' action is set to a php-page, which mails the email after sanitizing etc... I have to filter away spam etc so that my email-server don't get blacklisted or anything... I have my own server (VPS, Linux) and have thought about a solution... How does this sound to you: 1- Install a mail-server 2- Configure Firewall to ONLY allow connections to the mail-server from my website 3- Configure the mail-server so that a maximum of 'x' emails may be sent every 5 minutes or so 4- Create a php filter before sending the mail, which checks for 'bad' words. 5- If necessary, as last resort, ask the user a question (ex 5+5) before submitting form I would rather preferr if I didn't have to implement the 5th implementation above... What do you think? Also, another q I have that you may answer is: If an email-server gets blacklisted, is there any way to un-blacklist it? Or whats the solution if this happens? Thanks

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  • HTML5 Local Storage of audio element source - is it possible?

    - by andrewdotcom
    Hi stackoverflow experts I've been experimenting with the audio and local storage features of html5 of late and have run into something that has me stumped. I'd like to be able to cache or store the source of the audio element locally to enable speedier and offline playback. The problem is I can't see how this is possible with the current implementation. I have tried the following using webkit: Creating a manifest file to set up local caching but the audio file appears not to be a cacheable item maybe due to the way it is stream or something I have also attempted to use javascript to put an audio object into local storage but the size of the mp3 makes this impossible due to memory issues (i think). I have tried to use the data uri and base64 to use the html as a audio transport that can be cached but again the filesize makes this prohibitive. Also the audio element does not seem to like this in webkit (works fine in mozilla) I have tried several methods of putting the data into the local database store. Again suffering the same issues as the other cases. I'd love to hear any other ideas anyone may have as to how I could achieve my goal of offline playback using caching/local storage in webkit.

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  • What to throw in a C++ class wrapping a C library ?

    - by ereOn
    I have to create a set of wrapping C++ classes around an existing C library. For many objects of the C library, the construction is done by calling something like britney_spears* create_britney_spears() and the opposite function void free_britney_spears(britney_spears* brit). If the allocation of a britney_spears fails, create_britney_spears() returns NULL. This is, as far as I know, a very common pattern. Now I want to wrap this inside a C++ class. //britney_spears.hpp class BritneySpears { public: BritneySpears(); private: boost::shared_ptr<britney_spears> m_britney_spears; }; And here is the implementation: // britney_spears.cpp BritneySpears::BritneySpears() : m_britney_spears(create_britney_spears(), free_britney_spears) { if (!m_britney_spears) { // Here I should throw something to abort the construction, but what ??! } } So the question is in the code sample: What should I throw to abort the constructor ? I know I can throw almost anything, but I want to know what is usually done. I have no other information about why the allocation failed. Should I create my own exception class ? Is there a std exception for such cases ? Many thanks.

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  • Would like some modelling tips for dependent values

    - by orjan
    I'm working on a model for a simple fishing competition and I have some issues with my design. The main class for the fishing game is Capture and it looks like this: public class Capture : Entity { public virtual int Weight { get; set; } public virtual int Length { get; set; } public virtual DateTime DateForCapture { get; set; } public virtual User CapturedBy { get; set; } public virtual Species Species { get; set; } } So far there´s no problem but I'm not really sure how to model the game. Every Species is connected to a reference weight that changes from year to year The number of point for a capture is its Weight divided by the current reference weight for the species. One way to solve the problem is to connect a capture to SpeciesReferenceWeight instead of Species public class SpeciesReferenceWeight : Entity { public virtual Species Species { get; set; } public virtual int ReferenceWeight { get; set; } public virtual int Year { get; set; } } But in that way that Capture is connected to the implementation details of the game and from my point of view a capture is still a capture even if it's not included in a game. The result I'm aiming for is like: http://hornalen.net/fishbonkern/2007/ that I wrote a couple of years ago with brute force sql and no domain model. I would be very happy for all kinds of feeback on this issue.

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  • Slowing process creation under Java?

    - by oconnor0
    I have a single, large heap (up to 240GB, though in the 20-40GB range for most of this phase of execution) JVM [1] running under Linux [2] on a server with 24 cores. We have tens of thousands of objects that have to be processed by an external executable & then load the data created by those executables back into the JVM. Each executable produces about half a megabyte of data (on disk) that when read right in, after the process finishes, is, of course, larger. Our first implementation was to have each executable handle only a single object. This involved the spawning of twice as many executables as we had objects (since we called a shell script that called the executable). Our CPU utilization would start off high, but not necessarily 100%, and slowly worsen. As we began measuring to see what was happening we noticed that the process creation time [3] continually slows. While starting at sub-second times it would eventually grow to take a minute or more. The actual processing done by the executable usually takes less than 10 seconds. Next we changed the executable to take a list of objects to process in an attempt to reduce the number of processes created. With batch sizes of a few hundred (~1% of our current sample size), the process creation times start out around 2 seconds & grow to around 5-6 seconds. Basically, why is it taking so long to create these processes as execution continues? [1] Oracle JDK 1.6.0_22 [2] Red Hat Enterprise Linux Advanced Platform 5.3, Linux kernel 2.6.18-194.26.1.el5 #1 SMP [3] Creation of the ProcessBuilder object, redirecting the error stream, and starting it.

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  • implementing user tracking (logging) in Rails 3

    - by seth.vargo
    Hi, I'm creating a Rails application in which logging individual user actions is vital. Every time a user clicks a url, I want to log the action along with all parameters. Here is my current implementation: class CreateActivityLogs < ActiveRecord::Migration create_table :activity_logs do |t| t.references :user t.string :ip_address t.string :referring_url t.string :current_url t.text :params t.text :action t.timestamps end end   class ActivityLog < ActiveRecord::Base belongs_to :user end In a controller, I'd like to be able to do something like the following: ... ActivityLog::log @user.id, params, 'did foo with bar' ... I'd like to have the ActivityLog::log method automatically get the IP address, referring url, and current url (I know how to do this already) and create a new record in the table. So, my questions are: How do I do this? How do I use ActivityLog without having to create an instance everytime I want to log? Is this the best way? Some people have argued for a flat-file log for this kind of logging - however, I want admins to be able to see a user's activity in the backend as well, so I thought a database solution may be better?

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  • Integrating jQuery autocomplete with Google site search

    - by user1715700
    I have a bit of an odd situation. I have to implement search on a public facing website -but, that search must be able to search both web pages and have an autocomplete/suggestion functionality that comes from a list of terms that are in a DB table. So, I'm wondering a couple things: 1) should I be looking at Google search and jQuery autocomplete? 2) is there something else I should be looking at instead? 3) if this is the right path to be heading down are the enough pointers on implementation? The crux of my problem is that the terms that I need to use for the autocomplete/suggest functionality reside within a database and not on the webpages. So, I thought Google would be appropriate for search the webpages and that I could sort of fill in the blanks so to speak with these terms from the DB. I'm going to say that there are roughly 20-40,000 terms or so that need autocomplete. But that is really just a very rough guess -it could be less. I'm open to ideas and not really married to any particular solution. However, I will admit to liking the ideas of offloading the search to Google. I hear they have a good algorithm ;) Any ideas, thoughts, or leads are greatly appreciated!

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  • what are good ways to implement search and search results using ajax?

    - by Amr ElGarhy
    i have some text box in a page and in the same page there will be a table 'grid' like for holding the search result. When the user start editing and of the textbox above, the search must start by sending all textboxs values to the server 'ajax', and get back with the results to fill the below grid. Notes: This grid should support paging, sorting by clicking on headers and it will contains some controls beside the results such as checkboxs for boolean values and links for opening details in another page. I know many ways to do this some of them are: 1- updatepanel around all of these controls and thats it "fast dirty solution" 2- send the search criteria using ajax request using JQuery post function for example and get back the JSON result, and using a template will draw the grid "clean but will take time to finish and will be harder to edit later". 3- .... My question is: What do you think will be the best choice to implement this scenario? because i face this scenario too much, and want to know which implementation will be better regarding performance, optimization, and time to finish. I just want to know your thoughts about this issue.

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  • guarantee child records either in one table or another, but not both?

    - by user151841
    I have a table with two child tables. For each record in the parent table, I want one and only one record in one of the child tables -- not one in each, not none. How to I define that? Here's the backstory. Feel free to criticize this implementation, but please answer the question above, because this isn't the only time I've encountered it: I have a database that holds data pertaining to user surveys. It was originally designed with one authentication method for starting a survey. Since then, requirements have changed, and now there are two different ways someone could sign on to start a survey. Originally I captured the authentication token in a column in the survey table. Since requirements changed, there are three other bits of data that I want to capture in authentication. So for each record in the survey table, I'm either going to have one token, or a set of three. All four of these are of different types, so my thought was, instead of having four columns where either one is going to be null, or three are going to be null ( or even worse, a bad mashup of either of those scenarios ), I would have two child tables, one for holding the single authentication token, the other for holding the three. Problem is, I don't know offhand how to define that in DDL. I'm using MySQL, so maybe there's a feature that MySQL doesn't implement that lets me do this.

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  • Can AutoMapper create a map for an interface and then map with a derived type?

    - by TheCloudlessSky
    I have an interface IFoo: public interface IFoo { int Id { get; set; } } And then a concrete implementation: public class Bar : IFoo { public int Id { get; set; } public string A { get; set; } } public class Baz : IFoo { public int Id { get; set; } public string B { get; set; } } I'd like to be able to map all IFoo but specifying their derived type instead: Mapper.CreateMap<int, IFoo>().AfterMap((id, foo) => foo.Id = id); And then map (without explicitly creating maps for Bar and Baz): var bar = Mapper.Map<int, Bar>(123); // bar.Id == 123 var baz = Mapper.Map<int, Baz>(456); // baz.Id == 456 But this doesn't work in 1.1. I know I could specify all Bar and Baz but if there are 20 of these, I'd like to not have to manage them and rather just have what I did above for creating the map. Is this possible?

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  • STLifying C++ classes

    - by shambulator
    I'm trying to write a class which contains several std::vectors as data members, and provides a subset of vector's interface to access them: class Mesh { public: private: std::vector<Vector3> positions; std::vector<Vector3> normals; // Several other members along the same lines }; The main thing you can do with a mesh is add positions, normals and other stuff to it. In order to allow an STL-like way of accessing a Mesh (add from arrays, other containers, etc.), I'm toying with the idea of adding methods like this: public: template<class InIter> void AddNormals(InIter first, InIter last); Problem is, from what I understand of templates, these methods will have to be defined in the header file (seems to make sense; without a concrete iterator type, the compiler doesn't know how to generate object code for the obvious implementation of this method). Is this actually a problem? My gut reaction is not to go around sticking huge chunks of code in header files, but my C++ is a little rusty with not much STL experience outside toy examples, and I'm not sure what "acceptable" C++ coding practice is on this. Is there a better way to expose this functionality while retaining an STL-like generic programming flavour? One way would be something like this: (end list) class RestrictedVector<T> { public: RestrictedVector(std::vector<T> wrapped) : wrapped(wrapped) {} template <class InIter> void Add(InIter first, InIter last) { std::copy(first, last, std::back_insert_iterator(wrapped)); } private: std::vector<T> wrapped; }; and then expose instances of these on Mesh instead, but that's starting to reek a little of overengineering :P Any advice is greatly appreciated!

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  • Graph not following orientation

    - by user1214037
    so I am trying to draw some grid lines that in landscape go all the way down to the bottom, however when I switch to landscape the the graph doesn't follow and the grid lines go smaller. I have set the - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return YES; } However it still doesn't work, here is my code. Can anyone spot the problem? this is the custom view file, the view controller is the default apart from the code above that returns yes. .h file #import <UIKit/UIKit.h> #define kGraphHeight 300 #define kDefaultGraphWidth 900 #define kOffsetX 10 #define kStepX 50 #define kGraphBottom 300 #define kGraphTop 0 @interface GraphView : UIView @end And here is the implementation - (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetLineWidth(context, 0.6); CGContextSetStrokeColorWithColor(context, [[UIColor lightGrayColor] CGColor]); // How many lines? int howMany = (kDefaultGraphWidth - kOffsetX) / kStepX; // Here the lines go for (int i = 0; i < howMany; i++) { CGContextMoveToPoint(context, kOffsetX + i * kStepX, kGraphTop); CGContextAddLineToPoint(context, kOffsetX + i * kStepX, kGraphBottom); } CGContextStrokePath(context); } Any help would be appreciated btw I am following this tutorial http://buildmobile.com/creating-a-graph-with-quartz-2d/#fbid=YDPLqDHZ_9X

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  • NSTimer won't stop it only resets when invalidated & released

    - by J Fries
    When I press my stop button to stop the timer it just resets to the original time and begins counting down again. I have looked everywhere and all I have found is "invalidate" and it isn't working. I want the time to stop when I hit stop and the label to display the original time. I also turned off automatic counting so I could try releasing and it is giving me an error: 0x10e20a5: movl 16(%edx), %edx EXC_BAD_ACCESS (code=2, address=0x10) `NSTimer *rockettTimer; int rocketCount; @interface FirstViewController () @property (strong, nonatomic) IBOutlet UILabel *rocketTimer; - (IBAction)stopButton:(id)sender; - (IBAction)startButton:(id)sender; @end @implementation FirstViewController @synthesize rocketTimer; -(void) rocketTimerRun{ rocketCount = rocketCount - 1; int minuts = rocketCount / 60; int seconds = rocketCount - (minuts * 60); NSString *timerOutput = [NSString stringWithFormat:@"%d:%.2d", minuts, seconds]; rocketTimer.text = timerOutput; } - (IBAction)startButton:(id)sender { rocketCount = 180; rockettTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(rocketTimerRun) userInfo:nil repeats:YES]; - (IBAction)stopButton:(id)sender { [rockettTimer invalidate]; //[rockettTimer release]; } - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. } - (void)viewDidUnload { [self setRocketTimer:nil]; [super viewDidUnload]; // Release any retained subviews of the main view. } - (BOOL)shouldAutorotateToInterfaceOrientation: (UIInterfaceOrientation)interfaceOrientation { if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) { return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown); } else { return YES; } } @end`

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  • Abstract away a compound identity value for use in business logic?

    - by John K
    While separating business logic and data access logic into two different assemblies, I want to abstract away the concept of identity so that the business logic deals with one consistent identity without having to understand its actual representation in the data source. I've been calling this a compound identity abstraction. Data sources in this project are swappable and various and the business logic shouldn't care which data source is currently in use. The identity is the toughest part because its implementation can change per kind of data source, whereas other fields like name, address, etc are consistently scalar values. What I'm searching for is a good way to abstract the concept of identity, whether it be an existing library, a software pattern or just a solid good idea of some kind is provided. The proposed compound identity value would have to be comparable and usable in the business logic and passed back to the data source to specify records, entities and/or documents to affect, so the data source must be able to parse back out the details of its own compound ids. Data Source Examples: This serves to provide an idea of what I mean by various data sources having different identity implementations. A relational data source might express a piece of content with an integer identifier plus a language specific code. For example. content_id language Other Columns expressing details of content 1 en_us 1 fr_ca The identity of the first record in the above example is: 1 + en_us However when a NoSQL data source is substituted, it might somehow represent each piece of content with a GUID string 936DA01F-9ABD-4d9d-80C7-02AF85C822A8 plus language code of a different standardization, And a third kind of data source might use just a simple scalar value. So on and so forth, you get the idea.

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  • Would there be a market for this idea (cross platform VM for iPhone OS)

    - by Tzury Bar Yochay
    For a long time I wondered if the following idea worth a nickel or just a waste of time and energy. I am willing to start a project which will provide a kind of a VM for all iPxxx apps - so developed once for iPxxx can run on a Macbook, iMac, Linux, Android and windows (desktop and mobile). You get the idea, right? I want to do to the current iPhone SDK, the same as what Mono did to Microsoft .Net and perhaps a more complete set of implementation. I tend to believe that if overnight all apps on appstore become available on the android market as well that would be a mini revolution. Think about running iPad apps on every tablet that will come out to the market in the future. Wouldn't it be fantastic to all the developers, which from now on, can write once and sell everywhere? The main questions which I ask myself repeatedly is: "Is This Legal?" - I mean, say I have done this, would apple's lawyers will start sending me all kinds of nasty emails? I am willing to hear your opinion about this idea as well as if some of you willing and able to join forces and start this open source project.

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  • Make an abstract class or use a processor?

    - by Tim Murphy
    I'm developing a class to compare two directories and run an action when a directory/file in the source directory does not exist in destination directory. Here is a prototype of the class: public abstract class IdenticalDirectories { private DirectoryInfo _sourceDirectory; private DirectoryInfo _destinationDirectory; protected abstract void DirectoryExists(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void DirectoryDoesNotExist(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void FileExists(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void FileDoesNotExist(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); public IdenticalDirectories(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory) { ... } public void Run() { foreach (DirectoryInfo sourceSubDirectory in _sourceDirectory.GetDirectories()) { DirectoryInfo destinationSubDirectory = this.GetDestinationDirectoryInfo(subDirectory); if (destinationSubDirectory.Exists()) { this.DirectoryExists(sourceSubDirectory, destinationSubDirectory); } else { this.DirectoryDoesNotExist(sourceSubDirectory, destinationSubDirectory); } foreach (FileInfo sourceFile in sourceSubDirectory.GetFiles()) { FileInfo destinationFile = this.GetDestinationFileInfo(sourceFile); if (destinationFile.Exists()) { this.FileExists(sourceFile, destinationFile); } else { this.FileDoesNotExist(sourceFile, destinationFile); } } } } } The above prototype is an abstract class. I'm wondering if it would be better to make the class non-abstract and have the Run method receiver a processor? eg. public void Run(IIdenticalDirectoriesProcessor processor) { foreach (DirectoryInfo sourceSubDirectory in _sourceDirectory.GetDirectories()) { DirectoryInfo destinationSubDirectory = this.GetDestinationDirectoryInfo(subDirectory); if (destinationSubDirectory.Exists()) { processor.DirectoryExists(sourceSubDirectory, destinationSubDirectory); } else { processor.DirectoryDoesNotExist(sourceSubDirectory, destinationSubDirectory); } foreach (FileInfo sourceFile in sourceSubDirectory.GetFiles()) { FileInfo destinationFile = this.GetDestinationFileInfo(sourceFile); if (destinationFile.Exists()) { processor.FileExists(sourceFile, destinationFile); } else { processor.FileDoesNotExist(sourceFile, destinationFile); } } } } What do you see as the pros and cons of each implementation?

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  • (Java) Is there a type of object that can handle anything from primitives to arrays?

    - by Michael
    I'm pretty new to Java, so I'm hoping one of you guys knows how to do this. I'm having the user specify both the type and value of arguments, in any XML-like way, to be passed to methods that are external to my application. Example: javac myAppsName externalJavaClass methodofExternalClass [parameters] Of course, to find the proper method, we have to have the proper parameter types as the method may be overloaded and that's the only way to tell the difference between the different versions. Parameters are currently formatted in this manner: (type)value(/type), e.g. (int)71(/int) (string)This is my string that I'm passing as a parameter!(/string) I parse them, getting the constructor for whatever type is indicated, then execute that constructor by running its method, newInstance(<String value>), loading the new instance into an Object. This works fine and dandy, but as we all know, some methods take arrays, or even multi-dimensional arrays. I could handle the argument formatting like so: (array)(array)(int)0(/int)(int)1(/int)(/array)(array)(int)2(/int)(int)3(/int)(/array)(/array)... or perhaps even better... {{(int)0(/int)(int)1(/int)}{(int)2(/int)(int)3(/int)}}. The question is, how can this be implemented? Do I have to start wrapping everything in an Object[] array so I can handle primitives, etc. as argObj[0], but load an array as I normally would? (Unfortunately, I would have to make it an Object[][] array if I wanted to support two-dimensional arrays. This implementation wouldn't be very pretty.)

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  • recvfrom() return values in Stop-and-Wait UDP?

    - by mavErick
    I am trying to implement a Stop-and-Wait UDP client-server socket program in C. As known, there are basically three possible scenarios for Stop-and-Wait flow control. i.e., After transmitting a packet, the sender receives a correct ACK and thus starts transmitting the next packet; the sender receives an incorrect ACK and thus retransmits this packet; the sender receives no ACK within a TIMEOUT and thus retransmits this packet. My idea is to differentiate these three scenarios with the return value of recvfrom() on the sender side. For scenario 1&2: recvfrom() just returns the length of the received ACK. Since in my implementation the incorrect ACK is of the same length of the correct one, so I will have to go deeper and check the contents of the ACK. It's not a big deal. I know how to do. Problems come when I am trying to recognize scenario 3 where no ACK is received. What confuses me is that my recvfrom() is within a while loop, so the recvfrom() will be called constantly. What will it return when the receiver is not actually sending the sender ACK? Is it 0 or 1?

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  • How specific do I get in BDD scenarios?

    - by CodeSpelunker
    Take two different ways of stating the same behavior. Option A: Given a customer has 50 items in their shopping cart When they check out Then they will receive a 10% discount on their order Option B: Given a customer has a high volume of items in their shopping cart When they check out Then they will receive a high volume discount on their order The former is far more specific. If someone has some question about exactly when a customer gets a high volume discount or how much to give them, reading this scenario makes it very clear. Serving the purposes of documenting the behavior, it's about as specific as it can be, although any change in those values will require changing the scenario. The second is more generalized and doesn't have the clarity of the first. Automating it would require incorporating the values "50" and "10" in the step implementations. On the other hand, the scenario captures the core business need: a high volume customer gets a discount. If we later decide to use "40" and "15", the scenario doesn't have to change because the core business need hasn't really changed (though the step implementation would). Also, the term "high volume customer" communicates something about why we're giving them the discount. So, which is better? Rather, under what circumstances should I favor the former or the latter?

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  • java class that simulates a simple database table

    - by ericso
    I have a collection of heterogenous data that I pull from a database table mtable. Then, for every unique value uv in column A, I compute a function of (SELECT * FROM mtable WHERE A=uv). Then I do the same for column B, and column C. There are rather a lot of unique values, so I don't want to hit the db repeatedly - I would rather have a class that replicates some of the functionality (most importantly some version of SELECT WHERE). Additionally, I would like to abstract the column names away from the class definition, if that makes any sense - the constructor should take a list of names as a parameter, and also, I suppose, a list of types (right now this is just a String[], which seems hacky). I'm getting the initial data from a RowSet. I've more or less done this by using a hashmap that maps Strings to lists/arrays of Objects, but I keep getting bogged down in comparisons and types, and am thinking that my current implementation really isn't as clean and clear as it could be. I'm pretty new to java, also, and am not sure if I'm not going down a completely incorrect path. Does anyone have any suggestions?

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  • Make All Types Constant by Default in C++

    - by Jon Purdy
    What is the simplest and least obtrusive way to indicate to the compiler, whether by means of compiler options, #defines, typedefs, or templates, that every time I say T, I really mean T const? I would prefer not to make use of an external preprocessor. Since I don't use the mutable keyword, that would be acceptable to repurpose to indicate mutable state. Potential (suboptimal) solutions so far: // I presume redefinition of keywords is implementation-defined or illegal. #define int int const #define ptr * const int i(0); int ptr j(&i); typedef int const Int; typedef int const* const Intp; Int i(0); Intp j(&i); template<class T> struct C { typedef T const type; typedef T const* const ptr; }; C<int>::type i(0); C<int>::ptr j(&i);

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