Search Results

Search found 1971 results on 79 pages for 'crazy coder'.

Page 1/79 | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >

  • Red Gate Coder interviews: Alex Davies

    - by Michael Williamson
    Alex Davies has been a software engineer at Red Gate since graduating from university, and is currently busy working on .NET Demon. We talked about tackling parallel programming with his actors framework, a scientific approach to debugging, and how JavaScript is going to affect the programming languages we use in years to come. So, if we start at the start, how did you get started in programming? When I was seven or eight, I was given a BBC Micro for Christmas. I had asked for a Game Boy, but my dad thought it would be better to give me a proper computer. For a year or so, I only played games on it, but then I found the user guide for writing programs in it. I gradually started doing more stuff on it and found it fun. I liked creating. As I went into senior school I continued to write stuff on there, trying to write games that weren’t very good. I got a real computer when I was fourteen and found ways to write BASIC on it. Visual Basic to start with, and then something more interesting than that. How did you learn to program? Was there someone helping you out? Absolutely not! I learnt out of a book, or by experimenting. I remember the first time I found a loop, I was like “Oh my God! I don’t have to write out the same line over and over and over again any more. It’s amazing!” When did you think this might be something that you actually wanted to do as a career? For a long time, I thought it wasn’t something that you would do as a career, because it was too much fun to be a career. I thought I’d do chemistry at university and some kind of career based on chemical engineering. And then I went to a careers fair at school when I was seventeen or eighteen, and it just didn’t interest me whatsoever. I thought “I could be a programmer, and there’s loads of money there, and I’m good at it, and it’s fun”, but also that I shouldn’t spoil my hobby. Now I don’t really program in my spare time any more, which is a bit of a shame, but I program all the rest of the time, so I can live with it. Do you think you learnt much about programming at university? Yes, definitely! I went into university knowing how to make computers do anything I wanted them to do. However, I didn’t have the language to talk about algorithms, so the algorithms course in my first year was massively important. Learning other language paradigms like functional programming was really good for breadth of understanding. Functional programming influences normal programming through design rather than actually using it all the time. I draw inspiration from it to write imperative programs which I think is actually becoming really fashionable now, but I’ve been doing it for ages. I did it first! There were also some courses on really odd programming languages, a bit of Prolog, a little bit of C. Having a little bit of each of those is something that I would have never done on my own, so it was important. And then there are knowledge-based courses which are about not programming itself but things that have been programmed like TCP. Those are really important for examples for how to approach things. Did you do any internships while you were at university? Yeah, I spent both of my summers at the same company. I thought I could code well before I went there. Looking back at the crap that I produced, it was only surpassed in its crappiness by all of the other code already in that company. I’m so much better at writing nice code now than I used to be back then. Was there just not a culture of looking after your code? There was, they just didn’t hire people for their abilities in that area. They hired people for raw IQ. The first indicator of it going wrong was that they didn’t have any computer scientists, which is a bit odd in a programming company. But even beyond that they didn’t have people who learnt architecture from anyone else. Most of them had started straight out of university, so never really had experience or mentors to learn from. There wasn’t the experience to draw from to teach each other. In the second half of my second internship, I was being given tasks like looking at new technologies and teaching people stuff. Interns shouldn’t be teaching people how to do their jobs! All interns are going to have little nuggets of things that you don’t know about, but they shouldn’t consistently be the ones who know the most. It’s not a good environment to learn. I was going to ask how you found working with people who were more experienced than you… When I reached Red Gate, I found some people who were more experienced programmers than me, and that was difficult. I’ve been coding since I was tiny. At university there were people who were cleverer than me, but there weren’t very many who were more experienced programmers than me. During my internship, I didn’t find anyone who I classed as being a noticeably more experienced programmer than me. So, it was a shock to the system to have valid criticisms rather than just formatting criticisms. However, Red Gate’s not so big on the actual code review, at least it wasn’t when I started. We did an entire product release and then somebody looked over all of the UI of that product which I’d written and say what they didn’t like. By that point, it was way too late and I’d disagree with them. Do you think the lack of code reviews was a bad thing? I think if there’s going to be any oversight of new people, then it should be continuous rather than chunky. For me I don’t mind too much, I could go out and get oversight if I wanted it, and in those situations I felt comfortable without it. If I was managing the new person, then maybe I’d be keener on oversight and then the right way to do it is continuously and in very, very small chunks. Have you had any significant projects you’ve worked on outside of a job? When I was a teenager I wrote all sorts of stuff. I used to write games, I derived how to do isomorphic projections myself once. I didn’t know what the word was so I couldn’t Google for it, so I worked it out myself. It was horrifically complicated. But it sort of tailed off when I started at university, and is now basically zero. If I do side-projects now, they tend to be work-related side projects like my actors framework, NAct, which I started in a down tools week. Could you explain a little more about NAct? It is a little C# framework for writing parallel code more easily. Parallel programming is difficult when you need to write to shared data. Sometimes parallel programming is easy because you don’t need to write to shared data. When you do need to access shared data, you could just have your threads pile in and do their work, but then you would screw up the data because the threads would trample on each other’s toes. You could lock, but locks are really dangerous if you’re using more than one of them. You get interactions like deadlocks, and that’s just nasty. Actors instead allows you to say this piece of data belongs to this thread of execution, and nobody else can read it. If you want to read it, then ask that thread of execution for a piece of it by sending a message, and it will send the data back by a message. And that avoids deadlocks as long as you follow some obvious rules about not making your actors sit around waiting for other actors to do something. There are lots of ways to write actors, NAct allows you to do it as if it was method calls on other objects, which means you get all the strong type-safety that C# programmers like. Do you think that this is suitable for the majority of parallel programming, or do you think it’s only suitable for specific cases? It’s suitable for most difficult parallel programming. If you’ve just got a hundred web requests which are all independent of each other, then I wouldn’t bother because it’s easier to just spin them up in separate threads and they can proceed independently of each other. But where you’ve got difficult parallel programming, where you’ve got multiple threads accessing multiple bits of data in multiple ways at different times, then actors is at least as good as all other ways, and is, I reckon, easier to think about. When you’re using actors, you presumably still have to write your code in a different way from you would otherwise using single-threaded code. You can’t use actors with any methods that have return types, because you’re not allowed to call into another actor and wait for it. If you want to get a piece of data out of another actor, then you’ve got to use tasks so that you can use “async” and “await” to await asynchronously for it. But other than that, you can still stick things in classes so it’s not too different really. Rather than having thousands of objects with mutable state, you can use component-orientated design, where there are only a few mutable classes which each have a small number of instances. Then there can be thousands of immutable objects. If you tend to do that anyway, then actors isn’t much of a jump. If I’ve already built my system without any parallelism, how hard is it to add actors to exploit all eight cores on my desktop? Usually pretty easy. If you can identify even one boundary where things look like messages and you have components where some objects live on one side and these other objects live on the other side, then you can have a granddaddy object on one side be an actor and it will parallelise as it goes across that boundary. Not too difficult. If we do get 1000-core desktop PCs, do you think actors will scale up? It’s hard. There are always in the order of twenty to fifty actors in my whole program because I tend to write each component as actors, and I tend to have one instance of each component. So this won’t scale to a thousand cores. What you can do is write data structures out of actors. I use dictionaries all over the place, and if you need a dictionary that is going to be accessed concurrently, then you could build one of those out of actors in no time. You can use queuing to marshal requests between different slices of the dictionary which are living on different threads. So it’s like a distributed hash table but all of the chunks of it are on the same machine. That means that each of these thousand processors has cached one small piece of the dictionary. I reckon it wouldn’t be too big a leap to start doing proper parallelism. Do you think it helps if actors get baked into the language, similarly to Erlang? Erlang is excellent in that it has thread-local garbage collection. C# doesn’t, so there’s a limit to how well C# actors can possibly scale because there’s a single garbage collected heap shared between all of them. When you do a global garbage collection, you’ve got to stop all of the actors, which is seriously expensive, whereas in Erlang garbage collections happen per-actor, so they’re insanely cheap. However, Erlang deviated from all the sensible language design that people have used recently and has just come up with crazy stuff. You can definitely retrofit thread-local garbage collection to .NET, and then it’s quite well-suited to support actors, even if it’s not baked into the language. Speaking of language design, do you have a favourite programming language? I’ll choose a language which I’ve never written before. I like the idea of Scala. It sounds like C#, only with some of the niggles gone. I enjoy writing static types. It means you don’t have to writing tests so much. When you say it doesn’t have some of the niggles? C# doesn’t allow the use of a property as a method group. It doesn’t have Scala case classes, or sum types, where you can do a switch statement and the compiler checks that you’ve checked all the cases, which is really useful in functional-style programming. Pattern-matching, in other words. That’s actually the major niggle. C# is pretty good, and I’m quite happy with C#. And what about going even further with the type system to remove the need for tests to something like Haskell? Or is that a step too far? I’m quite a pragmatist, I don’t think I could deal with trying to write big systems in languages with too few other users, especially when learning how to structure things. I just don’t know anyone who can teach me, and the Internet won’t teach me. That’s the main reason I wouldn’t use it. If I turned up at a company that writes big systems in Haskell, I would have no objection to that, but I wouldn’t instigate it. What about things in C#? For instance, there’s contracts in C#, so you can try to statically verify a bit more about your code. Do you think that’s useful, or just not worthwhile? I’ve not really tried it. My hunch is that it needs to be built into the language and be quite mathematical for it to work in real life, and that doesn’t seem to have ended up true for C# contracts. I don’t think anyone who’s tried them thinks they’re any good. I might be wrong. On a slightly different note, how do you like to debug code? I think I’m quite an odd debugger. I use guesswork extremely rarely, especially if something seems quite difficult to debug. I’ve been bitten spending hours and hours on guesswork and not being scientific about debugging in the past, so now I’m scientific to a fault. What I want is to see the bug happening in the debugger, to step through the bug happening. To watch the program going from a valid state to an invalid state. When there’s a bug and I can’t work out why it’s happening, I try to find some piece of evidence which places the bug in one section of the code. From that experiment, I binary chop on the possible causes of the bug. I suppose that means binary chopping on places in the code, or binary chopping on a stage through a processing cycle. Basically, I’m very stupid about how I debug. I won’t make any guesses, I won’t use any intuition, I will only identify the experiment that’s going to binary chop most effectively and repeat rather than trying to guess anything. I suppose it’s quite top-down. Is most of the time then spent in the debugger? Absolutely, if at all possible I will never debug using print statements or logs. I don’t really hold much stock in outputting logs. If there’s any bug which can be reproduced locally, I’d rather do it in the debugger than outputting logs. And with SmartAssembly error reporting, there’s not a lot that can’t be either observed in an error report and just fixed, or reproduced locally. And in those other situations, maybe I’ll use logs. But I hate using logs. You stare at the log, trying to guess what’s going on, and that’s exactly what I don’t like doing. You have to just look at it and see does this look right or wrong. We’ve covered how you get to grip with bugs. How do you get to grips with an entire codebase? I watch it in the debugger. I find little bugs and then try to fix them, and mostly do it by watching them in the debugger and gradually getting an understanding of how the code works using my process of binary chopping. I have to do a lot of reading and watching code to choose where my slicing-in-half experiment is going to be. The last time I did it was SmartAssembly. The old code was a complete mess, but at least it did things top to bottom. There wasn’t too much of some of the big abstractions where flow of control goes all over the place, into a base class and back again. Code’s really hard to understand when that happens. So I like to choose a little bug and try to fix it, and choose a bigger bug and try to fix it. Definitely learn by doing. I want to always have an aim so that I get a little achievement after every few hours of debugging. Once I’ve learnt the codebase I might be able to fix all the bugs in an hour, but I’d rather be using them as an aim while I’m learning the codebase. If I was a maintainer of a codebase, what should I do to make it as easy as possible for you to understand? Keep distinct concepts in different places. And name your stuff so that it’s obvious which concepts live there. You shouldn’t have some variable that gets set miles up the top of somewhere, and then is read miles down to choose some later behaviour. I’m talking from a very much SmartAssembly point of view because the old SmartAssembly codebase had tons and tons of these things, where it would read some property of the code and then deal with it later. Just thousands of variables in scope. Loads of things to think about. If you can keep concepts separate, then it aids me in my process of fixing bugs one at a time, because each bug is going to more or less be understandable in the one place where it is. And what about tests? Do you think they help at all? I’ve never had the opportunity to learn a codebase which has had tests, I don’t know what it’s like! What about when you’re actually developing? How useful do you find tests in finding bugs or regressions? Finding regressions, absolutely. Running bits of code that would be quite hard to run otherwise, definitely. It doesn’t happen very often that a test finds a bug in the first place. I don’t really buy nebulous promises like tests being a good way to think about the spec of the code. My thinking goes something like “This code works at the moment, great, ship it! Ah, there’s a way that this code doesn’t work. Okay, write a test, demonstrate that it doesn’t work, fix it, use the test to demonstrate that it’s now fixed, and keep the test for future regressions.” The most valuable tests are for bugs that have actually happened at some point, because bugs that have actually happened at some point, despite the fact that you think you’ve fixed them, are way more likely to appear again than new bugs are. Does that mean that when you write your code the first time, there are no tests? Often. The chance of there being a bug in a new feature is relatively unaffected by whether I’ve written a test for that new feature because I’m not good enough at writing tests to think of bugs that I would have written into the code. So not writing regression tests for all of your code hasn’t affected you too badly? There are different kinds of features. Some of them just always work, and are just not flaky, they just continue working whatever you throw at them. Maybe because the type-checker is particularly effective around them. Writing tests for those features which just tend to always work is a waste of time. And because it’s a waste of time I’ll tend to wait until a feature has demonstrated its flakiness by having bugs in it before I start trying to test it. You can get a feel for whether it’s going to be flaky code as you’re writing it. I try to write it to make it not flaky, but there are some things that are just inherently flaky. And very occasionally, I’ll think “this is going to be flaky” as I’m writing, and then maybe do a test, but not most of the time. How do you think your programming style has changed over time? I’ve got clearer about what the right way of doing things is. I used to flip-flop a lot between different ideas. Five years ago I came up with some really good ideas and some really terrible ideas. All of them seemed great when I thought of them, but they were quite diverse ideas, whereas now I have a smaller set of reliable ideas that are actually good for structuring code. So my code is probably more similar to itself than it used to be back in the day, when I was trying stuff out. I’ve got more disciplined about encapsulation, I think. There are operational things like I use actors more now than I used to, and that forces me to use immutability more than I used to. The first code that I wrote in Red Gate was the memory profiler UI, and that was an actor, I just didn’t know the name of it at the time. I don’t really use object-orientation. By object-orientation, I mean having n objects of the same type which are mutable. I want a constant number of objects that are mutable, and they should be different types. I stick stuff in dictionaries and then have one thing that owns the dictionary and puts stuff in and out of it. That’s definitely a pattern that I’ve seen recently. I think maybe I’m doing functional programming. Possibly. It’s plausible. If you had to summarise the essence of programming in a pithy sentence, how would you do it? Programming is the form of art that, without losing any of the beauty of architecture or fine art, allows you to produce things that people love and you make money from. So you think it’s an art rather than a science? It’s a little bit of engineering, a smidgeon of maths, but it’s not science. Like architecture, programming is on that boundary between art and engineering. If you want to do it really nicely, it’s mostly art. You can get away with doing architecture and programming entirely by having a good engineering mind, but you’re not going to produce anything nice. You’re not going to have joy doing it if you’re an engineering mind. Architects who are just engineering minds are not going to enjoy their job. I suppose engineering is the foundation on which you build the art. Exactly. How do you think programming is going to change over the next ten years? There will be an unfortunate shift towards dynamically-typed languages, because of JavaScript. JavaScript has an unfair advantage. JavaScript’s unfair advantage will cause more people to be exposed to dynamically-typed languages, which means other dynamically-typed languages crop up and the best features go into dynamically-typed languages. Then people conflate the good features with the fact that it’s dynamically-typed, and more investment goes into dynamically-typed languages. They end up better, so people use them. What about the idea of compiling other languages, possibly statically-typed, to JavaScript? It’s a reasonable idea. I would like to do it, but I don’t think enough people in the world are going to do it to make it pick up. The hordes of beginners are the lifeblood of a language community. They are what makes there be good tools and what makes there be vibrant community websites. And any particular thing which is the same as JavaScript only with extra stuff added to it, although it might be technically great, is not going to have the hordes of beginners. JavaScript is always to be quickest and easiest way for a beginner to start programming in the browser. And dynamically-typed languages are great for beginners. Compilers are pretty scary and beginners don’t write big code. And having your errors come up in the same place, whether they’re statically checkable errors or not, is quite nice for a beginner. If someone asked me to teach them some programming, I’d teach them JavaScript. If dynamically-typed languages are great for beginners, when do you think the benefits of static typing start to kick in? The value of having a statically typed program is in the tools that rely on the static types to produce a smooth IDE experience rather than actually telling me my compile errors. And only once you’re experienced enough a programmer that having a really smooth IDE experience makes a blind bit of difference, does static typing make a blind bit of difference. So it’s not really about size of codebase. If I go and write up a tiny program, I’m still going to get value out of writing it in C# using ReSharper because I’m experienced with C# and ReSharper enough to be able to write code five times faster if I have that help. Any other visions of the future? Nobody’s going to use actors. Because everyone’s going to be running on single-core VMs connected over network-ready protocols like JSON over HTTP. So, parallelism within one operating system is going to die. But until then, you should use actors. More Red Gater Coder interviews

    Read the article

  • iPhone Serialization problem

    - by Jenicek
    Hi, I need to save my own created class to file, I found on the internet, that good approach is to use NSKeyedArchiver and NSKeyedUnarchiver My class definition looks like this: @interface Game : NSObject <NSCoding> { NSMutableString *strCompleteWord; NSMutableString *strWordToGuess; NSMutableArray *arGuessedLetters; //This array stores characters NSMutableArray *arGuessedLettersPos; //This array stores CGRects NSInteger iScore; NSInteger iLives; NSInteger iRocksFallen; BOOL bGameCompleted; BOOL bGameOver; } I've implemented methods initWithCoder: and encodeWithCoder: this way: - (id)initWithCoder:(NSCoder *)coder { if([coder allowsKeyedCoding]) { strCompleteWord = [[coder decodeObjectForKey:@"CompletedWord"] copy]; strWordToGuess = [[coder decodeObjectForKey:@"WordToGuess"] copy]; arGuessedLetters = [[coder decodeObjectForKey:@"GuessedLetters"] retain]; // arGuessedLettersPos = [[coder decodeObjectForKey:@"GuessedLettersPos"] retain]; iScore = [coder decodeIntegerForKey:@"Score"]; iLives = [coder decodeIntegerForKey:@"Lives"]; iRocksFallen = [coder decodeIntegerForKey:@"RocksFallen"]; bGameCompleted = [coder decodeBoolForKey:@"GameCompleted"]; bGameOver = [coder decodeBoolForKey:@"GameOver"]; } else { strCompleteWord = [[coder decodeObject] retain]; strWordToGuess = [[coder decodeObject] retain]; arGuessedLetters = [[coder decodeObject] retain]; // arGuessedLettersPos = [[coder decodeObject] retain]; [coder decodeValueOfObjCType:@encode(NSInteger) at:&iScore]; [coder decodeValueOfObjCType:@encode(NSInteger) at:&iLives]; [coder decodeValueOfObjCType:@encode(NSInteger) at:&iRocksFallen]; [coder decodeValueOfObjCType:@encode(BOOL) at:&bGameCompleted]; [coder decodeValueOfObjCType:@encode(BOOL) at:&bGameOver]; } return self; } - (void)encodeWithCoder:(NSCoder *)coder { if([coder allowsKeyedCoding]) { [coder encodeObject:strCompleteWord forKey:@"CompleteWord"]; [coder encodeObject:strWordToGuess forKey:@"WordToGuess"]; [coder encodeObject:arGuessedLetters forKey:@"GuessedLetters"]; //[coder encodeObject:arGuessedLettersPos forKey:@"GuessedLettersPos"]; [coder encodeInteger:iScore forKey:@"Score"]; [coder encodeInteger:iLives forKey:@"Lives"]; [coder encodeInteger:iRocksFallen forKey:@"RocksFallen"]; [coder encodeBool:bGameCompleted forKey:@"GameCompleted"]; [coder encodeBool:bGameOver forKey:@"GameOver"]; } else { [coder encodeObject:strCompleteWord]; [coder encodeObject:strWordToGuess]; [coder encodeObject:arGuessedLetters]; //[coder encodeObject:arGuessedLettersPos]; [coder encodeValueOfObjCType:@encode(NSInteger) at:&iScore]; [coder encodeValueOfObjCType:@encode(NSInteger) at:&iLives]; [coder encodeValueOfObjCType:@encode(NSInteger) at:&iRocksFallen]; [coder encodeValueOfObjCType:@encode(BOOL) at:&bGameCompleted]; [coder encodeValueOfObjCType:@encode(BOOL) at:&bGameOver]; } } And I use these methods to archive and unarchive data: [NSKeyedArchiver archiveRootObject:currentGame toFile:strPath]; Game *currentGame = [NSKeyedUnarchiver unarchiveObjectWithFile:strPath]; I have two problems. 1) As you can see, lines with arGuessedLettersPos is commented, it's because every time I try to encode this array, error comes up(this archiver cannot encode structs), and this array is used for storing CGRect structs. I've seen solution on the internet. The thing is, that every CGRect in the array is converted to an NSString (using NSStringFromCGRect()) and then saved. Is it a good approach? 2)This is bigger problem for me. Even if I comment this line and then run the code successfully, then save(archive) the data and then try to load (unarchive) them, no data is loaded. There aren't any error but currentGame object does not have data that should be loaded. Could you please give me some advice? This is first time I'm using archivers and unarchivers. Thanks a lot for every reply.

    Read the article

  • how to get Geo::Coder::Many with cpan?

    - by mnemonic
    Ubuntu is installed for development of a Perl project. aptitude search Geo-Coder i libgeo-coder-googlev3-perl - Perl module providing access to Google Map Aptitude does not refer to Geo::Coder::Many cpan can not build it. sudo cpan Geo::Coder::Many Then: CPAN: Storable loaded ok (v2.27) Going to read '/home/jh/.cpan/Metadata' Database was generated on Wed, 16 Oct 2013 06:17:04 GMT Running install for module 'Geo::Coder::Many' Running make for K/KA/KAORU/Geo-Coder-Many-0.42.tar.gz CPAN: Digest::SHA loaded ok (v5.61) CPAN: Compress::Zlib loaded ok (v2.033) Checksum for /home/jh/.cpan/sources/authors/id/K/KA/KAORU/Geo-Coder-Many-0.42.tar.gz ok CPAN: File::Temp loaded ok (v0.22) CPAN: Parse::CPAN::Meta loaded ok (v1.4401) CPAN: CPAN::Meta loaded ok (v2.110440) CPAN: Module::CoreList loaded ok (v2.49_02) CPAN: Module::Build loaded ok (v0.38) CPAN.pm: Going to build K/KA/KAORU/Geo-Coder-Many-0.42.tar.gz Can't locate Geo/Coder/Many/Google.pm in @INC (@INC contains: /etc/perl /usr/local/lib/perl/5.14.2 /usr/local/share/perl/5.14.2 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.14 /usr/share/perl/5.14 /usr/local/lib/site_perl .) at /usr/share/perl/5.14/Module/Load.pm line 27. Can't locate Geo/Coder/Many/Google in @INC (@INC contains: /etc/perl /usr/local/lib/perl/5.14.2 /usr/local/share/perl/5.14.2 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.14 /usr/share/perl/5.14 /usr/local/lib/site_perl .) at /usr/share/perl/5.14/Module/Load.pm line 27. BEGIN failed--compilation aborted at Build.PL line 54. Warning: No success on command[/usr/bin/perl Build.PL --installdirs site] CPAN: YAML loaded ok (v0.77) KAORU/Geo-Coder-Many-0.42.tar.gz /usr/bin/perl Build.PL --installdirs site -- NOT OK Running Build test Make had some problems, won't test Running Build install Make had some problems, won't install Could not read metadata file. Falling back to other methods to determine prerequisites Any suggestions how to resolve this issue?

    Read the article

  • Crazy TableView (Or more likely me being just a jerk) ;-)

    - by Miky Mike
    Hi guy, I'm going crazy with all that objective C. I went to bed at 1.30 pm today, spending the night on my app but I love it... Well that's not the point anyway... My question is .... I have a table view which evaluates a statement when it displays its data : it goes like this : - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"CustomCell"; cell = ((MainCell *)[self.tableView dequeueReusableCellWithIdentifier:CellIdentifier]); if (cell == nil) { [[NSBundle mainBundle] loadNibNamed:@"MainCell" owner:self options:nil]; } Entry *entry = [fetchedResultsController objectAtIndexPath:indexPath]; cell.topLabel.text = [@"* " stringByAppendingString: entry.entryname]; cell.bottomLabel.text = entry.textbody; if ([entry.active boolValue] == YES) { cell.cellImageView.image = [UIImage imageNamed:@"check.png"]; } else { cell.cellImageView.image = nil; cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton; } return cell; } The problem is that the first time it displays the data, the conditions are met when I scroll down the tableview but when I scroll up, sometimes, I get my "check.png" image and the accessory as well, which is not possible normally. Am I going crazy or is it the tableview ? Could you help me with that please, I can't figure out why it doesn't work... :-(( Thanks a lot in advance. Mike

    Read the article

  • Programming Pearls (2nd Edition) vs More Programming Pearls: Confessions of a Coder [closed]

    - by Geek
    I have been reading very good reviews of the books by Jon Bentley : Programming Pearls (2nd Edition) More Programming Pearls: Confessions of a Coder. I know that these books have been out there for a long time and I feel bad that I haven't read either one . But it is always better late than never . I understand that the second one was written after the first one . So are these two books complementary to each other ? Do the second one assume that the reader has read the first one ? For some one who haven't read either which one would you propose to read up first ?

    Read the article

  • Red Gate Coder interviews: Robin Hellen

    - by Michael Williamson
    Robin Hellen is a test engineer here at Red Gate, and is also the latest coder I’ve interviewed. We chatted about debugging code, the roles of software engineers and testers, and why Vala is currently his favourite programming language. How did you get started with programming?It started when I was about six. My dad’s a professional programmer, and he gave me and my sister one of his old computers and taught us a bit about programming. It was an old Amiga 500 with a variant of BASIC. I don’t think I ever successfully completed anything! It was just faffing around. I didn’t really get anywhere with it.But then presumably you did get somewhere with it at some point.At some point. The PC emerged as the dominant platform, and I learnt a bit of Visual Basic. I didn’t really do much, just a couple of quick hacky things. A bit of demo animation. Took me a long time to get anywhere with programming, really.When did you feel like you did start to get somewhere?I think it was when I started doing things for someone else, which was my sister’s final year of university project. She called up my dad two days before she was due to submit, saying “We need something to display a graph!”. Dad says, “I’m too busy, go talk to your brother”. So I hacked up this ugly piece of code, sent it off and they won a prize for that project. Apparently, the graph, the bit that I wrote, was the reason they won a prize! That was when I first felt that I’d actually done something that was worthwhile. That was my first real bit of code, and the ugliest code I’ve ever written. It’s basically an array of pre-drawn line elements that I shifted round the screen to draw a very spikey graph.When did you decide that programming might actually be something that you wanted to do as a career?It’s not really a decision I took, I always wanted to do something with computers. And I had to take a gap year for uni, so I was looking for twelve month internships. I applied to Red Gate, and they gave me a job as a tester. And that’s where I really started having to write code well. To a better standard that I had been up to that point.How did you find coming to Red Gate and working with other coders?I thought it was really nice. I learnt so much just from other people around. I think one of the things that’s really great is that people are just willing to help you learn. Instead of “Don’t you know that, you’re so stupid”, it’s “You can just do it this way”.If you could go back to the very start of that internship, is there something that you would tell yourself?Write shorter code. I have a tendency to write massive, many-thousand line files that I break out of right at the end. And then half-way through a project I’m doing something, I think “Where did I write that bit that does that thing?”, and it’s almost impossible to find. I wrote some horrendous code when I started. Just that principle, just keep things short. Even if looks a bit crazy to be jumping around all over the place all of the time, it’s actually a lot more understandable.And how do you hold yourself to that?Generally, if a function’s going off my screen, it’s probably too long. That’s what I tell myself, and within the team here we have code reviews, so the guys I’m with at the moment are pretty good at pulling me up on, “Doesn’t that look like it’s getting a bit long?”. It’s more just the subjective standard of readability than anything.So you’re an advocate of code review?Yes, definitely. Both to spot errors that you might have made, and to improve your knowledge. The person you’re reviewing will say “Oh, you could have done it that way”. That’s how we learn, by talking to others, and also just sharing knowledge of how your project works around the team, or even outside the team. Definitely a very firm advocate of code reviews.Do you think there’s more we could do with them?I don’t know. We’re struggling with how to add them as part of the process without it becoming too cumbersome. We’ve experimented with a few different ways, and we’ve not found anything that just works.To get more into the nitty gritty: how do you like to debug code?The first thing is to do it in my head. I’ll actually think what piece of code is likely to have caused that error, and take a quick look at it, just to see if there’s anything glaringly obvious there. The next thing I’ll probably do is throw in print statements, or throw some exceptions from various points, just to check: is it going through the code path I expect it to? A last resort is to actually debug code using a debugger.Why is the debugger the last resort?Probably because of the environments I learnt programming in. VB and early BASIC didn’t have much of a debugger, the only way to find out what your program was doing was to add print statements. Also, because a lot of the stuff I tend to work with is non-interactive, if it’s something that takes a long time to run, I can throw in the print statements, set a run off, go and do something else, and look at it again later, rather than trying to remember what happened at that point when I was debugging through it. So it also gives me the record of what happens. I hate just sitting there pressing F5, F5, continually. If you’re having to find out what your code is doing at each line, you’ve probably got a very wrong mental model of what your code’s doing, and you can find that out just as easily by inspecting a couple of values through the print statements.If I were on some codebase that you were also working on, what should I do to make it as easy as possible to understand?I’d say short and well-named methods. The one thing I like to do when I’m looking at code is to find out where a value comes from, and the more layers of indirection there are, particularly DI [dependency injection] frameworks, the harder it is to find out where something’s come from. I really hate that. I want to know if the value come from the user here or is a constant here, and if I can’t find that out, that makes code very hard to understand for me.As a tester, where do you think the split should lie between software engineers and testers?I think the split is less on areas of the code you write and more what you’re designing and creating. The developers put a structure on the code, while my major role is to say which tests we should have, whether we should test that, or it’s not worth testing that because it’s a tiny function in code that nobody’s ever actually going to see. So it’s not a split in the code, it’s a split in what you’re thinking about. Saying what code we should write, but alternatively what code we should take out.In your experience, do the software engineers tend to do much testing themselves?They tend to control the lowest layer of tests. And, depending on how the balance of people is in the team, they might write some of the higher levels of test. Or that might go to the testers. I’m the only tester on my team with three other developers, so they’ll be writing quite a lot of the actual test code, with input from me as to whether we should test that functionality, whereas on other teams, where it’s been more equal numbers, the testers have written pretty much all of the high level tests, just because that’s the best use of resource.If you could shuffle resources around however you liked, do you think that the developers should be writing those high-level tests?I think they should be writing them occasionally. It helps when they have an understanding of how testing code works and possibly what assumptions we’ve made in tests, and they can say “actually, it doesn’t work like that under the hood so you’ve missed this whole area”. It’s one of those agile things that everyone on the team should be at least comfortable doing the various jobs. So if the developers can write test code then I think that’s a very good thing.So you think testers should be able to write production code?Yes, although given most testers skills at coding, I wouldn’t advise it too much! I have written a few things, and I did make a few changes that have actually gone into our production code base. They’re not necessarily running every time but they are there. I think having that mix of skill sets is really useful. In some ways we’re using our own product to test itself, so being able to make those changes where it’s not working saves me a round-trip through the developers. It can be really annoying if the developers have no time to make a change, and I can’t touch the code.If the software engineers are consistently writing tests at all levels, what role do you think the role of a tester is?I think on a team like that, those distinctions aren’t quite so useful. There’ll be two cases. There’s either the case where the developers think they’ve written good tests, but you still need someone with a test engineer mind-set to go through the tests and validate that it’s a useful set, or the correct set for that code. Or they won’t actually be pure developers, they’ll have that mix of test ability in there.I think having slightly more distinct roles is useful. When it starts to blur, then you lose that view of the tests as a whole. The tester job is not to create tests, it’s to validate the quality of the product, and you don’t do that just by writing tests. There’s more things you’ve got to keep in your mind. And I think when you blur the roles, you start to lose that end of the tester.So because you’re working on those features, you lose that holistic view of the whole system?Yeah, and anyone who’s worked on the feature shouldn’t be testing it. You always need to have it tested it by someone who didn’t write it. Otherwise you’re a bit too close and you assume “yes, people will only use it that way”, but the tester will come along and go “how do people use this? How would our most idiotic user use this?”. I might not test that because it might be completely irrelevant. But it’s coming in and trying to have a different set of assumptions.Are you a believer that it should all be automated if possible?Not entirely. So an automated test is always better than a manual test for the long-term, but there’s still nothing that beats a human sitting in front of the application and thinking “What could I do at this point?”. The automated test is very good but they follow that strict path, and they never check anything off the path. The human tester will look at things that they weren’t expecting, whereas the automated test can only ever go “Is that value correct?” in many respects, and it won’t notice that on the other side of the screen you’re showing something completely wrong. And that value might have been checked independently, but you always find a few odd interactions when you’re going through something manually, and you always need to go through something manually to start with anyway, otherwise you won’t know where the important bits to write your automation are.When you’re doing that manual testing, do you think it’s important to do that across the entire product, or just the bits that you’ve touched recently?I think it’s important to do it mostly on the bits you’ve touched, but you can’t ignore the rest of the product. Unless you’re dealing with a very, very self-contained bit, you’re almost always encounter other bits of the product along the way. Most testers I know, even if they are looking at just one path, they’ll keep open and move around a bit anyway, just because they want to find something that’s broken. If we find that your path is right, we’ll go out and hunt something else.How do you think this fits into the idea of continuously deploying, so long as the tests pass?With deploying a website it’s a bit different because you can always pull it back. If you’re deploying an application to customers, when you’ve released it, it’s out there, you can’t pull it back. Someone’s going to keep it, no matter how hard you try there will be a few installations that stay around. So I’d always have at least a human element on that path. With websites, you could probably automate straight out, or at least straight out to an internal environment or a single server in a cloud of fifty that will serve some people. But I don’t think you should release to everyone just on automated tests passing.You’ve already mentioned using BASIC and C# — are there any other languages that you’ve used?I’ve used a few. That’s something that has changed more recently, I’ve become familiar with more languages. Before I started at Red Gate I learnt a bit of C. Then last year, I taught myself Python which I actually really enjoyed using. I’ve also come across another language called Vala, which is sort of a C#-like language. It’s basically a pre-processor for C, but it has very nice syntax. I think that’s currently my favourite language.Any particular reason for trying Vala?I have a completely Linux environment at home, and I’ve been looking for a nice language, and C# just doesn’t cut it because I won’t touch Mono. So, I was looking for something like C# but that was useable in an open source environment, and Vala’s what I found. C#’s got a few features that Vala doesn’t, and Vala’s got a few features where I think “It would be awesome if C# had that”.What are some of the features that it’s missing?Extension methods. And I think that’s the only one that really bugs me. I like to use them when I’m writing C# because it makes some things really easy, especially with libraries that you can’t touch the internals of. It doesn’t have method overloading, which is sometimes annoying.Where it does win over C#?Everything is non-nullable by default, you never have to check that something’s unexpectedly null.Also, Vala has code contracts. This is starting to come in C# 4, but the way it works in Vala is that you specify requirements in short phrases as part of your function signature and they stick to the signature, so that when you inherit it, it has exactly the same code contract as the base one, or when you inherit from an interface, you have to match the signature exactly. Just using those makes you think a bit more about how you’re writing your method, it’s not an afterthought when you’ve got contracts from base classes given to you, you can’t change it. Which I think is a lot nicer than the way C# handles it. When are those actually checked?They’re checked both at compile and run-time. The compile-time checking isn’t very strong yet, it’s quite a new feature in the compiler, and because it compiles down to C, you can write C code and interface with your methods, so you can bypass that compile-time check anyway. So there’s an extra runtime check, and if you violate one of the contracts at runtime, it’s game over for your program, there’s no exception to catch, it’s just goodbye!One thing I dislike about C# is the exceptions. You write a bit of code and fifty exceptions could come from any point in your ten lines, and you can’t mentally model how those exceptions are going to come out, and you can’t even predict them based on the functions you’re calling, because if you’ve accidentally got a derived class there instead of a base class, that can throw a completely different set of exceptions. So I’ve got no way of mentally modelling those, whereas in Vala they’re checked like Java, so you know only these exceptions can come out. You know in advance the error conditions.I think Raymond Chen on Old New Thing says “the only thing you know when you throw an exception is that you’re in an invalid state somewhere in your program, so just kill it and be done with it!”You said you’ve also learnt bits of Python. How did you find that compared to Vala and C#?Very different because of the dynamic typing. I’ve been writing a website for my own use. I’m quite into photography, so I take photos off my camera, post-process them, dump them in a file, and I get a webpage with all my thumbnails. So sort of like Picassa, but written by myself because I wanted something to learn Python with. There are some things that are really nice, I just found it really difficult to cope with the fact that I’m not quite sure what this object type that I’m passed is, I might not ever be sure, so it can randomly blow up on me. But once I train myself to ignore that and just say “well, I’m fairly sure it’s going to be something that looks like this, so I’ll use it like this”, then it’s quite nice.Any particular features that you’ve appreciated?I don’t like any particular feature, it’s just very straightforward to work with. It’s very quick to write something in, particularly as you don’t have to worry that you’ve changed something that affects a different part of the program. If you have, then that part blows up, but I can get this part working right now.If you were doing a big project, would you be willing to do it in Python rather than C# or Vala?I think I might be willing to try something bigger or long term with Python. We’re currently doing an ASP.NET MVC project on C#, and I don’t like the amount of reflection. There’s a lot of magic that pulls values out, and it’s all done under the scenes. It’s almost managed to put a dynamic type system on top of C#, which in many ways destroys the language to me, whereas if you’re already in a dynamic language, having things done dynamically is much more natural. In many ways, you get the worst of both worlds. I think for web projects, I would go with Python again, whereas for anything desktop, command-line or GUI-based, I’d probably go for C# or Vala, depending on what environment I’m in.It’s the fact that you can gain from the strong typing in ways that you can’t so much on the web app. Or, in a web app, you have to use dynamic typing at some point, or you have to write a hell of a lot of boilerplate, and I’d rather use the dynamic typing than write the boilerplate.What do you think separates great programmers from everyone else?Probably design choices. Choosing to write it a piece of code one way or another. For any given program you ask me to write, I could probably do it five thousand ways. A programmer who is capable will see four or five of them, and choose one of the better ones. The excellent programmer will see the largest proportion and manage to pick the best one very quickly without having to think too much about it. I think that’s probably what separates, is the speed at which they can see what’s the best path to write the program in. More Red Gater Coder interviews

    Read the article

  • Freezes for unknown reasons, causing fan to go crazy on a Portege laptop

    - by Sünnje
    I have recently installed Natty on a new Toshiba Portege laptop. I find it extremely irritating that the system freezes frequently, about every other time I use the computer. Then the fan goes crazy and I have to force-shutdown. It seems to happen no matter what I do; I encountered this problem when using Firefox, LibreOffice, Adobe Reader - probably when using only terminals too, but I'm not certain. It may be fan-related, because the computer seems to get heated up compared compared to earlier, but I am not sure about that. Any ideas why this could be happening?

    Read the article

  • What do you do with coder's block?

    - by Garet Claborn
    Lately it has been a bit rough. I basically know all the things I need and all the avenues to get there for work. There's been no real issue of a problem with too high complexity, and performance is good. Still, after three major projects this year, my mind is behaving a little strange. It's like I'm used to working in O(1+log(N-neatTricks)) but for some reason it processes in O(N^2)! I've experienced a sort of burnout after long deadlines and drudging projects before, but when it turns into a longer experience, I haven't found the usual suspects to be helpful. Take more walks Work on other code Overdesign everything until I feel intensely driven to just make it (sorta works) How can a programmer recoup from the specific hole in your head programming leaves after being mentally ransacked by these bloody corporations and their fancy money? Hopefully some of you have some better ideas, because I could really use another round of being looted and pillaged.I've often wondered if there are special puzzles or some kind of activity that would de-stress the tangled balance of left and right braininess programmers often deal with. Do any special techniques, activities, anything seem to help with the developer's mindset especially?

    Read the article

  • When overriding initWithCoder is it always necessary to call [super initWithCoder: coder]

    - by Evan
    In this code I am loading a View Controller (and associated View) from a .xib: -(id)initWithCoder:(NSCoder *)coder { [super initWithCoder:coder]; return self; } This successfully works, but I do not really understand what the line [super initWithCoder:coder] is accomplishing. Is that initializing my View Controller after my View has been initialized? Please be as explicit as possible when explaining. Thanks.

    Read the article

  • Unit Testing DateTime – The Crazy Way

    - by João Angelo
    We all know that the process of unit testing code that depends on DateTime, particularly the current time provided through the static properties (Now, UtcNow and Today), it’s a PITA. If you go ask how to unit test DateTime.Now on stackoverflow I’ll bet that you’ll get two kind of answers: Encapsulate the current time in your own interface and use a standard mocking framework; Pull out the big guns like Typemock Isolator, JustMock or Microsoft Moles/Fakes and mock the static property directly. Now each alternative has is pros and cons and I would have to say that I glean more to the second approach because the first adds a layer of abstraction just for the sake of testability. However, the second approach depends on commercial tools that not every shop wants to buy or in the not so friendly Microsoft Moles. (Sidenote: Moles is now named Fakes and it will ship with VS 2012) This tends to leave people without an acceptable and simple solution so after reading another of these types of questions in SO I came up with yet another alternative, one based on the first alternative that I presented here but tries really hard to not get in your way with yet another layer of abstraction. So, without further dues, I present you, the Tardis. The Tardis is single section of conditionally compiled code that overrides the meaning of the DateTime expression inside a single class. You still get the normal coding experience of using DateTime all over the place, but in a DEBUG compilation your tests will be able to mock every static method or property of the DateTime class. An example follows, while the full Tardis code can be downloaded from GitHub: using System; using NSubstitute; using NUnit.Framework; using Tardis; public class Example { public Example() : this(string.Empty) { } public Example(string title) { #if DEBUG this.DateTime = DateTimeProvider.Default; this.Initialize(title); } internal IDateTimeProvider DateTime { get; set; } internal Example(string title, IDateTimeProvider provider) { this.DateTime = provider; #endif this.Initialize(title); } private void Initialize(string title) { this.Title = title; this.CreatedAt = DateTime.UtcNow; } private string title; public string Title { get { return this.title; } set { this.title = value; this.UpdatedAt = DateTime.UtcNow; } } public DateTime CreatedAt { get; private set; } public DateTime UpdatedAt { get; private set; } } public class TExample { public void T001() { // Arrange var tardis = Substitute.For<IDateTimeProvider>(); tardis.UtcNow.Returns(new DateTime(2000, 1, 1, 6, 6, 6)); // Act var sut = new Example("Title", tardis); // Assert Assert.That(sut.CreatedAt, Is.EqualTo(tardis.UtcNow)); } public void T002() { // Arrange var tardis = Substitute.For<IDateTimeProvider>(); var sut = new Example("Title", tardis); tardis.UtcNow.Returns(new DateTime(2000, 1, 1, 6, 6, 6)); // Act sut.Title = "Updated"; // Assert Assert.That(sut.UpdatedAt, Is.EqualTo(tardis.UtcNow)); } } This approach is also suitable for other similar classes with commonly used static methods or properties like the ConfigurationManager class.

    Read the article

  • SPRoleAssignment Crazy Caviats

    - by MOSSLover
    I’m not sure if this bug exists on any other environment, but here are a few issues I ran into when trying to use SPRoleAssignment and SPGroup: When trying to use Web.Groups[“GroupName”] it basically told me the group did not exist, so I had to change the code to use Web.SiteGroups[“GroupName”]. I could not add the Role Assignment to the Web and run a Web.Update() without adding an additional Web.AllowUnsafeUpdates= true; , however on my virtual machine I could do a Web.Update() without the extra piece of code.  I kept receiving an error in my browser stating that I should hit the back button and update my permissions. So after fixing those two issues I was able to copy the permissions from a page item into a Site for my migration.  Hopefully, one of you can learn from my error messages if you have any issues in the future. Technorati Tags: SPRoleAssignment,MOSS,SPGroup

    Read the article

  • Crazy Linq: performing System.ComponentModel.DataAnnotations validation in a single statement

    - by Daniel Cazzulino
    public static IEnumerable&lt;ValidationResult&gt; Validate(object component) { return from descriptor in TypeDescriptor.GetProperties(component).Cast&lt;PropertyDescriptor&gt;() from validation in descriptor.Attributes.OfType&lt;System.ComponentModel.DataAnnotations.ValidationAttribute&gt;() where !validation.IsValid(descriptor.GetValue(component)) select new ValidationResult( validation.ErrorMessage ?? string.Format(CultureInfo.CurrentUICulture, "{0} validation failed.", validation.GetType().Name), new[] { descriptor.Name }); } ...Read full article

    Read the article

  • Rhythmbox goes crazy if I change keyboard layout

    - by krokoziabla
    Not so trivial to explain but I'll try. Launch Rhythmbox Insert a CD in the CD-ROM The CD is not automatically identified (it's of a not very famous Russian band) I'm manually setting track names and... Magic, black magic! If I change the keyboard layout (RU <- EN) during editing then Rhythmbox kicks me out of the editing. So if a track name contains both Russian and English words I'm compelled to write one part, press Enter (so that the changes are not lost), change layout, click on the track name, write another part in the opposite layout. In some tricky names I have to do this several times. By the way, I use Alt+Shift to change layout. Any ideas?

    Read the article

  • For On Page SEO, This Works Like Crazy

    When it comes to the search engines we need to be making sure that our website tells the search engines exactly what it is and what the content contained within is about. Once we have this right, which will come from the on page optimization and content, we need to build backlinks to our website which increases the popularity of our website in the search engines eyes and lifts us up through the rankings.

    Read the article

  • Coder rapidement ou écrire du code de qualité ? Les deux approches reviendraient au même, selon un célèbre développeur dessinateur

    Coder rapidement ou écrire du code de qualité ? Les deux approches reviennent au même, selon un célèbre web-bédéiste XKCD est une célèbre bande-dessinée créée et publiée par Randall Munroe, un ancien consultant à la NASA, qui la définit comme un webcomic sarcastique qui parle de romance, de maths et de langage. Une planche publiée récemment sous forme d'organigramme algorithmique n'a d'autre prétention que celle de résumer, d'une manière extrêmement pessimiste, le métier de développeur. Les développeurs seraient, selon Munroe, éternellement confronté au dilemme : coder rapidement ou coder correctement. Ceux qui prennent la décision de "coder corr...

    Read the article

  • iPhone - archiving array of custom objects

    - by Dylan
    I've been trying for hours and I cannot solve this problem. I'm making an app that saves unfinished Chess Games, so I'm trying to write an array to a file. This is what the array is, if it makes sense: -NSMutableArray savedGames --GameSave a ---NSMutableArray board; ----Piece a, b, c, etc. -----some ints ---NSString whitePlayer, blackPlayer; ---int playerOnTop, turn; --GameSave b ---NSMutableArray board; ----Piece a, b, c, etc. -----some ints ---NSString whitePlayer, blackPlayer; ---int playerOnTop, turn; etc. And these are my NSCoding methods: GameSave.m - (void)encodeWithCoder:(NSCoder *)coder { [coder encodeObject:whitePlayer forKey:@"whitePlayer"]; [coder encodeObject:blackPlayer forKey:@"blackPlayer"]; [coder encodeInt:playerOnTop forKey:@"playerOnTop"]; [coder encodeInt:turn forKey:@"turn"]; [coder encodeObject:board forKey:@"board"]; } - (id)initWithCoder:(NSCoder *)coder { self = [[GameSave alloc] init]; if (self != nil) { board = [coder decodeObjectForKey:@"board"]; whitePlayer = [coder decodeObjectForKey:@"whitePlayer"]; blackPlayer = [coder decodeObjectForKey:@"blackPlayer"]; playerOnTop = [coder decodeIntForKey:@"playerOnTop"]; turn = [coder decodeIntForKey:@"turn"]; } return self; } Piece.m - (void)encodeWithCoder:(NSCoder *)coder { [coder encodeInt:color forKey:@"color"]; [coder encodeInt:piece forKey:@"piece"]; [coder encodeInt:row forKey:@"row"]; [coder encodeInt:column forKey:@"column"]; } - (id)initWithCoder:(NSCoder *)coder { self = [[Piece alloc] init]; if (self != nil) { color = [coder decodeIntForKey:@"color"]; piece = [coder decodeIntForKey:@"piece"]; row = [coder decodeIntForKey:@"row"]; column = [coder decodeIntForKey:@"column"]; } return self; } And this is the code that tries to archive and save to file: - (void)saveGame { ChessSaverAppDelegate *delegate = (ChessSaverAppDelegate *) [[UIApplication sharedApplication] delegate]; [[delegate gameSave] setBoard:board]; NSMutableArray *savedGames = [NSKeyedUnarchiver unarchiveObjectWithFile:[self dataFilePath]]; if (savedGames == nil) { [NSKeyedArchiver archiveRootObject:[delegate gameSave] toFile:[self dataFilePath]]; } else { [savedGames addObject:[delegate gameSave]]; [NSKeyedArchiver archiveRootObject:savedGames toFile:[self dataFilePath]]; } } - (NSString *)dataFilePath { NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; return [documentsDirectory stringByAppendingPathComponent:@"gameSaves.plist"]; } Sorry, here's the problem: After setting some breakpoints, an error is reached after this line from -saveGame: [NSKeyedArchiver archiveRootObject:savedGames toFile:[self dataFilePath]]; And this is what shows up in the console: 2010-05-11 17:04:08.852 ChessSaver[62065:207] *** -[NSCFType encodeWithCoder:]: unrecognized selector sent to instance 0x3d3cd30 2010-05-11 17:04:08.891 ChessSaver[62065:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSCFType encodeWithCoder:]: unrecognized selector sent to instance 0x3d3cd30' 2010-05-11 17:04:08.908 ChessSaver[62065:207] Stack: ( 32339035, 31077641, 32720955, 32290422, 32143042, 238843, 25827, 238843, 564412, 342037, 238843, 606848, 17686, 2733061, 4646817, 2733061, 3140430, 3149167, 3144379, 2837983, 2746312, 2773089, 41684313, 32123776, 32119880, 41678357, 41678554, 2777007, 9884, 9738 ) If it matters, -saveGame is called from a UIBarButton in a navigation controller. Any help is appreciated, thanks.

    Read the article

  • CPU on ubuntu goes crazy

    - by n179911
    Hi, I am running ubuntu 9.10. At the sudden the CPU goes crazy and when I do top, it is used by a command called 'dd' and it is run by USER 'root'. It keeps going to for 15 minutes. Can you please tell what is it doing? and if I can kill it by reboot my machine? Thank you.

    Read the article

  • Multi Monitor setup goes crazy after locking/unlocking Vista machine

    - by Mark Henderson
    My Vista Business machine, running Ultramon, has three monitors attached. When I lock the machine, the monitor layout stays correct. When I unlock it, I watch as all my screens flicker (as they are being re-configured), and Vista chooses some crazy layout for the monitors. The most recent one is below, but it's never consistent. Any ideas what might cause this? It's Vista Business, with UltraMon 3.0 (exiting Ultramon makes no difference).

    Read the article

  • Windows 7 System process reading/writing like crazy

    - by Mats Ekberg
    I have a problem that my windows 7 computer sometimes starts accessing the disk like crazy for maybe 10 minutes at a time. The process in question is the "system" process. I have disabled superfetch and hibernation on my computer, if that makes any difference. I disabled those to see if they were the cause of the problems, but no change. I have 6 GB of RAM and only the web browser was started when I took the screenshot, so I don't think it was thrashing due to page faults. Any ideas on how to find the cause of this?

    Read the article

  • Multi Monitor setup goes crazy after locking/unlocking Vista machine

    - by Farseeker
    Give me a 10-blade quad-processor quad-core Opteron centre and ask me to configure failover/load balancing and I'd be happy to, but the following problem has got me completely stumped. My Vista Business Professional machine, running Ultramon, has three monitors attached. When I lock the machine (to go to the delicious cafe around the corner), the monitor layout stays correct. When I unlock it, I watch as all my screens flicker (as they are being re-configured), and Vista chooses some crazy layout for the monitors. The most recent one is below, but it's never consistant. Any ideas what might cause this? It's Vista Business, with UltraMon 3.0 (exiting Ultramon makes no difference).

    Read the article

  • Javascript crazy idea finding a node

    - by Louis
    I had a crazy (but so crazy that it just might work) idea where every element on a page is created in javascript but given an ID which is a hash of its path in the DOM. So instead of searching through the DOM to find an element, you hash the path and then getElementById() with that hash. Problem with this is getting the path might be more expensive than searching the DOM in the first place. Any ideas how this could be done or if it is just plain stupid?

    Read the article

  • vb classic coder to android how to transition?

    - by user366654
    Hi guys. I'm a VB/vba coder and would like to start android dev. Currently I'm learning Java from scratch and. Its quite tough. I've read about oop but never actually written any OO code. Java syntax is also quite foreign but I'm getting the hang of it. My question is, which is absolutely the best transition path for a vb old dog to writing for froyo?

    Read the article

  • Difference between coder and programmer in common examples, rules

    - by MInner
    Real definition is a kind of definition based on out-of-subjects axioms, rules. (Subjective, I know.) It's easy to speak about 'difference ..' with person, who's in programming. But usually it's quite hard to show difference to the person who have never used to write program. How do you think - which examples, analogies, logical chains are best for showing this kind of difference. The only example, which comes to mind is - economist (coder) and mathematician (programmer). How do you feel about it?

    Read the article

1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >