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  • Calling a method on an unitialized object (null pointer)

    - by Florin
    What is the normal behavior in Objective-C if you call a method on an object (pointer) that is nil (maybe because someone forgot to initialize it)? Shouldn't it generate some kind of an error (segmentation fault, null pointer exception...)? If this is normal behavior, is there a way of changing this behavior (by configuring the compiler) so that the program raises some kind of error / exception at runtime? To make it more clear what I am talking about, here's an example. Having this class: @interface Person : NSObject { NSString *name; } @property (nonatomic, retain) NSString *name; - (void)sayHi; @end with this implementation: @implementation Person @synthesize name; - (void)dealloc { [name release]; [super dealloc]; } - (void)sayHi { NSLog(@"Hello"); NSLog(@"My name is %@.", name); } @end Somewhere in the program I do this: Person *person = nil; //person = [[Person alloc] init]; // let's say I comment this line person.name = @"Mike"; // shouldn't I get an error here? [person sayHi]; // and here [person release]; // and here

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  • Quickest algorithm for finding sets with high intersection

    - by conradlee
    I have a large number of user IDs (integers), potentially millions. These users all belong to various groups (sets of integers), such that there are on the order of 10 million groups. To simplify my example and get to the essence of it, let's assume that all groups contain 20 user IDs (i.e., all integer sets have a cardinality of 100). I want to find all pairs of integer sets that have an intersection of 15 or greater. Should I compare every pair of sets? (If I keep a data structure that maps userIDs to set membership, this would not be necessary.) What is the quickest way to do this? That is, what should my underlying data structure be for representing the integer sets? Sorted sets, unsorted---can hashing somehow help? And what algorithm should I use to compute set intersection)? I prefer answers that relate C/C++ (especially STL), but also any more general, algorithmic insights are welcome. Update Also, note that I will be running this in parallel in a shared memory environment, so ideas that cleanly extend to a parallel solution are preferred.

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  • WPF Grid Column MaxWidth not enforced

    - by Trevor Hartman
    This problem stems from not being able to get my TextBlock to wrap. Basically as a last-ditch attempt I am setting MaxWidth on my container grid's columns. I was surprised to find that my child label and textbox still do whatever they want (bad children, BAD) and are not limited by my grid column's MaxWidth="200". What I'm really trying to do is let my TextBlock fill available width and wrap if necessary. So far after trying many variations of HorizontalAlignment="Stretch" on every known parent in the universe, nothing works, except setting an explicit MaxWidth="400" or whatever number on the TextBlock. This is not good because I need the TextBlock to fill available width, not be limited by some fixed number. Thanks! <ItemsControl> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <StackPanel /> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> <ItemsControl.ItemTemplate> <DataTemplate> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition MaxWidth="200" SharedSizeGroup="A" /> <ColumnDefinition MaxWidth="200" SharedSizeGroup="B" /> </Grid.ColumnDefinitions> <Label VerticalAlignment="Top" Margin="0 5 0 0" Grid.Column="0" Style="{StaticResource LabelStyle}" Width="Auto" Content="{Binding Value.Summary}" /> <TextBlock Grid.Column="1" Margin="5,8,5,8" FontWeight="Normal" Background="AliceBlue" Foreground="Black" Text="{Binding Value.Description}" HorizontalAlignment="Stretch" TextWrapping="Wrap" Height="Auto" /> </Grid> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl>

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  • Django + jQuery: Sometimes AJAX, but always DRY?

    - by Justin Myles Holmes
    Let's say I have an app (in Django) for which I want to sometimes (but not always) load content via ajax. An easy example is logging in. When the user logs in, I don't want to refresh the page, just change things around. Yet, if they are already logged in, and then arrive at (or refresh) the same page, I want it to show the same content. So, in the first case, obviously I do some sort of ajax login and load changes to the page accordingly. Easy enough. But what about in the second case? Do I go back through and add {% if user.authenticated %} all over the place? This seems cold, dark, and WET. On the other hand, I can just wrap all the ajaxy stuff in a javascript function, called loggedIn(), and run that if the user is authenticated. But then I'm faced with two http requests instead of one. Also undesirable. So what's the standard solution here?

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  • Caching sitemaps in django

    - by michuk
    I implemented a simple sitemap class using django's default sitemap app. As it was taking a long time to execute, I added manual caching: class ShortReviewsSitemap(Sitemap): changefreq = "hourly" priority = 0.7 def items(self): # try to retrieve from cache result = get_cache(CACHE_SITEMAP_SHORT_REVIEWS, "sitemap_short_reviews") if result!=None: return result result = ShortReview.objects.all().order_by("-created_at") # store in cache set_cache(CACHE_SITEMAP_SHORT_REVIEWS, "sitemap_short_reviews", result) return result def lastmod(self, obj): return obj.updated_at The problem is that memcache allows only max 1MB object. This one was bigger that 1MB, so storing into cache failed: >7 SERVER_ERROR object too large for cache The problem is that django has an automated way of deciding when it should divide the sitemap file into smalled ones. According to the docs (http://docs.djangoproject.com/en/dev/ref/contrib/sitemaps/): You should create an index file if one of your sitemaps has more than 50,000 URLs. In this case, Django will automatically paginate the sitemap, and the index will reflect that. What do you think would be the best way to enable caching sitemaps? - Hacking into django sitemaps framework to restrict a single sitemap size to, let's say, 10,000 records seems like the best idea. Why was 50,000 chosen in the first place? Google advice? random number? - Or maybe there is a way to allow memcached store bigger files? - Or perhaps onces saved, the sitemaps should be made available as static files? This would mean that instead of caching with memcached I'd have to manually store the results in the filesystem and retrieve them from there next time when the sitemap is requested (perhaps cleaning the directory daily in a cron job). All those seem very low level and I'm wondering if an obvious solution exists...

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  • How to detect if an application has UI elements in it from C# in Windows 7?

    - by Santhosh
    I have a c# application in Windows 7 that runs in Session 0. This application is basically a framework for software patches installation that will install patches in the background (in session 0). So this app will download patches from the server and start installing them on the client machines. The way it installs the patches is by calling CreateProcess("Patch.exe"). Now mostly, Patch.exe will be a non-ui silent installation and henceforth, installing the patch from session 0 goes through successfully. However, sometimes this Patch.exe happens to have some UI elements in it such as prompting the user for some details (like installation location, etc..) and let us say that these UI elements cannot be avoided. So is it possible for my installation framework (that runs in Session 0 written in C#), to know that the process Patch.exe which was created by my framework has any UI elements in it? The reason I ask is, if I determine that the application has any UI elements in it, then I do not want to continue with the installation (a crude way of doing this would be to kill the installer process Patch.exe, but that is a different story and not of concern here).

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  • deadlock because of foreign key?

    - by George2
    Hello everyone, I am using SQL Server 2008 Enterprise. I met with deadlock in the following store procedure, but because of my fault, I did not record the deadlock graph. But now I can not reproduce deadlock issue. I want to have a postmortem to find the root cause of deadlock to avoid deadlock in the future. The deadlock happens on delete statement. For the delete statement, Param1 is a column of table FooTable, Param1 is a foreign key of another table (refers to another primary key clustered index column of the other table). There is no index on Param1 itself for table FooTable. FooTable has another column which is used as clustered primary key, but not Param1 column. Here is my guess why there is deadlock, and I want to let people review whether my analysis is correct? Since Param1 column has no index, there will be a table scan, and will acquire table level lock, because of foreign key, the delete operation will also need to check master table (e.g. to acquire lock on master table); Some operation on master table acquires master table lock, but want to acquire lock on FooTable; (1) and (2) cause cycle lock which makes deadlock happen. My analysis correct? Any reproduce scenario? create PROCEDURE [dbo].[FooProc] ( @Param1 int ,@Param2 int ,@Param3 int ) AS DELETE FooTable WHERE Param1 = @Param1 INSERT INTO FooTable ( Param1 ,Param2 ,Param3 ) VALUES ( @Param1 ,@Param2 ,@Param3 ) DECLARE @ID bigint SET @ID = ISNULL(@@Identity,-1) IF @ID > 0 BEGIN SELECT IdentityStr FROM FooTable WHERE ID = @ID END thanks in advance, George

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  • Translating CURL to FLEX HTTPRequests

    - by Joshua
    I am trying to convert from some CURL code to FLEX/ActionScript. Since I am 100% ignorant about CURL and 50% ignorant about Flex and 90% ignorant on HTTP in general... I'm having some significant difficulty. The following CURL code is from http://code.google.com/p/ga-api-http-samples/source/browse/trunk/src/v2/accountFeed.sh I have every reason to believe that it's working correctly. USER_EMAIL="[email protected]" #Insert your Google Account email here USER_PASS="secretpass" #Insert your password here googleAuth="$(curl https://www.google.com/accounts/ClientLogin -s \ -d Email=$USER_EMAIL \ -d Passwd=$USER_PASS \ -d accountType=GOOGLE \ -d source=curl-accountFeed-v2 \ -d service=analytics \ | awk /Auth=.*/)" feedUri="https://www.google.com/analytics/feeds/accounts/default\ ?prettyprint=true" curl $feedUri --silent \ --header "Authorization: GoogleLogin $googleAuth" \ --header "GData-Version: 2" The following is my abortive attempt to translate the above CURL to AS3 var request:URLRequest=new URLRequest("https://www.google.com/analytics/feeds/accounts/default"); request.method=URLRequestMethod.POST; var GoogleAuth:String="$(curl https://www.google.com/accounts/ClientLogin -s " + "-d [email protected] " + "-d Passwd=secretpass " + "-d accountType=GOOGLE " + "-d source=curl-accountFeed-v2" + "-d service=analytics " + "| awk /Auth=.*/)"; request.requestHeaders.push(new URLRequestHeader("Authorization", "GoogleLogin " + GoogleAuth)); request.requestHeaders.push(new URLRequestHeader("GData-Version", "2")); var loader:URLLoader=new URLLoader(); loader.dataFormat=URLLoaderDataFormat.BINARY; loader.addEventListener(Event.COMPLETE, GACompleteHandler); loader.addEventListener(IOErrorEvent.IO_ERROR, GAErrorHandler); loader.addEventListener(SecurityErrorEvent.SECURITY_ERROR, GAErrorHandler); loader.load(request); This probably provides you all with a good laugh, and that's okay, but if you can find any pity on me, please let me know what I'm missing. I readily admit functional ineptitude, therefore letting me know how stupid I am is optional.

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  • UIViewController remaining

    - by Guy
    Hi Guys. I have a UIViewController named equationVC who's user interface is being programmatically created from another NSObject class called equationCon. Upon loading equationVC, a method called chooseInterface is called from the equationCon class. I have a global variable (globalVar) that points to a user defined string. chooseInterface finds a method in the equationCon class that matches the string globalVar points to. In this case, let's say that globalVar points to a string that is called "methodThatMatches." In methodThatMatches, another view controller needs to show the results of what methodThatMatches did. methodThatMatches creates a new equationVC that calls upon methodThatMatches2. As a test, each method changes the color of the background. When the application starts up, I get a purple background, but as soon as I hit backwards I get another purple screen, which should be yellow. I do not think that I am release the view properly. Can anyone help? -(void)chooseInterface { NSString* equationTemp = [globalVar stringByReplacingOccurrencesOfString:@" " withString:@""]; equationTemp = [equationTemp stringByReplacingOccurrencesOfString:@"'" withString:@""]; SEL equationName = NSSelectorFromString(equationTemp); NSLog(@"selector! %@",NSStringFromSelector(equationName)); if([self respondsToSelector:equationName]){ [self performSelector:equationName]; } } -(void)methodThatMatches{ self.equationVC.view.backgroundColor = [UIColor yellowColor]; [setGlobalVar:@"methodThatMatches2"]; EquationVC* temp = [[EquationVC alloc] init]; [[self.equationVC navigationController] pushViewController:temp animated:YES ]; [temp release]; } -(void)methodThatmatches2{ self.equationVC.view.backgroundColor = [UIColor purpleColor]; }

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  • Serializing a part of object graph

    - by Felix
    Hi all, I have a problem regarding Java custom serialization. I have a graph of objects and want to configure where to stop when I serialize a root object from client to server. Let's make it a bit concrete, clear by giving a sample scenario. I have Classes of type Company Employee (abstract) Manager extends Employee Secretary extends Employee Analyst extends Employee Project Here are the relations: Company(1)---(n)Employee Manager(1)---(n)Project Analyst(1)---(n)Project Imagine, I'm on the client side and I want to create a new company, assign it 10 employees (new or some existing) and send this new company to the server. What I expect in this scenario is to serialize the company and all bounding employees to the server side, because I'll save the relations on the database. So far no problem, since the default Java serialization mechanism serializes the whole object graph, excluding the field which are static or transient. My goal is about the following scenario. Imagine, I loaded a company and its 1000 employees from the server to the client side. Now I only want to rename the company's name (or some other field, that directly belongs to the company) and update this record. This time, I want to send only the company object to the server side and not the whole list of employees (I just update the name, the employees are in this use case irrelevant). My aim also includes the configurability of saying, transfer the company AND the employees but not the Project-Relations, you must stop there. Do you know any possibility of achieving this in a generic way, without implementing the writeObject, readObject for every single Entity-Object? What would be your suggestions? I would really appreciate your answers. I'm open to any ideas and am ready to answer your questions in case something is not clear.

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  • SSIS: "Failure inserting into the read-only column <ColumnName>"

    - by Cory
    I have an Excel source going into an OLE DB destination. I'm inserting data into a view that has an INSTEAD OF trigger that handles all inserts. When I try to execute the package I receive this error: "Failure inserting into the read-only column ColumnName" What can I do to let SSIS know that this view is safe to insert into because there is an INSTEAD OF trigger that will handle the insert? EDIT (Additional info): Some more additional info. I have a flat file that is being inserted into a normalized database. My initial problem was how do I take a flat file and insert that data into multiple tables while keeping track of all the primary/foreign key relationships. My solution was to create a VIEW that mimicked the structure of the flat file and then create an INSTEAD OF trigger on that view. In my INSTEAD OF trigger I would handle the logic of maintaining all the relationships between tables My view looks something like this. CREATE VIEW ImportView AS SELECT CONVERT(varchar(100, NULL) AS CustomerName, CONVERT(varchar(100), NULL) AS Address1, CONVERT(varchar(100), NULL) AS Address2, CONVERT(varchar(100), NULL) AS City, CONVERT(char(2), NULL) AS State, CONVERT(varchar(250), NULL) AS ItemOrdered, CONVERT(int, NULL) AS QuantityOrdered ... I will never need to select from this view, I only use it to insert data into it from this flat file I receive. I need someway to tell SQL Server that the fields aren't really read only because there is an INSTEAD OF trigger on this view.

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  • VEMap and a GeoRSS feed(hosted separately)

    - by Alexis Abril
    The scenario is as follows: A WCF web service exists that outputs a valid GeoRSS feed. This lives in its own domain as a number of different applications have access to it. A web page(on a different site) has been created with an instance of a VEMap(Bing/Virtual Earth map object). Now, VEMap can accept an input feed in this format via the following: var layer = new VEShapeLayer(); var veLayerSpec = new VEShapeSourceSpecification(VEDataType.GeoRSS, "someurl", layer); map.ImportShapeLayerData(veLayerSpec, onComplete, true); onComplete is a callback function I'm using to replace the default pin graphic with something custom. The question is in regards to "someurl", which is a path to a local xml file containing the geographic information(georss simple format). I've realized this feed and the map must be hosted in the same domain, so I've created a generic handler that reads the remote feed and returns it in the same format. var veLayerSpec = new VEShapeSourceSpecification(VEDataType.GeoRSS, "/somelocalhandler.ashx", layer); When I do this, I get the VEMap error("z is null"). This is the same error one would receive when trying to access a remote feed. When I copy the feed into a local xml file(ie, "feed.xml") there is no error. The order of operations is currently: remote feed - local handler - VEMap import If I'm over complicating this procedure, let me know! I'm a bit new to the Bing Maps API and might have missed something. Any assistance is appreciated.

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  • Handling Errors in PHP

    - by Mike
    I have a custom class that, when called, will redirect to a page and send a 'message_type' and 'message' variable via GET. When the page opens it checks for these variables and displays a 'success', 'warning', or 'error' message depending on the 'message_type' variable. I made it so the user thinks they stay on the same page. It also allows for other variables to be passed along with the message. Is this good practice, or should I just start using exceptions? Example: //Call a static function that will redirect to a page, with an error message RedirectWithMessage::go('somepage.php', MessageType::ERROR, 'Error message here.'); The following checkMessage() function is an include file: function checkMessage() { if((isset($_GET['message_type']) && strlen($_GET['message_type'])) && (isset($_GET['message']) && strlen($_GET['message_type']))) { DisplayMessage::display($_GET['message_type'], $_GET['message']); return true; } return false; } On the page that is redirected to, call checkMessage(); //If a message is received, display it. If not, do nothing checkMessage(); I know this might be vague, and I can supply more code if necessary. I guess the issue is that I don't have much experience using exceptions, but I think they seem cumbersome (writing try-catch blocks everywhere). Please let me know if I am making this more difficult for myself or if there is a better solution. Thanks! Mike

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  • Awk filtering values between two files when regions intersect (any solutions welcome)

    - by user964689
    This is building upon an earlier question Awk conditional filter one file based on another (or other solutions) I have an awk program that outputs a column from rows in a text file 'refGene.txt if values in that row match 2 out of 3 values in another text file. I need to include an additional criteria for finding a match between the two files. The criteria is inclusion if the range of the 2 numberical values specified in each row in file 1 overlap with the range of the two values in a row in refGene.txt. An example of a line in File 1: chr1 10 20 chr2 10 20 and an example line in file 2(refGene.txt) of the matching columns ($3, $5, $ 6): chr1 5 30 Currently the awk program does not treat this as a match because although the first column matches neither the 2nd or 3rd columns do no. But I would like a way to treat this as a match because the region 10-20 in file 1 is WITHIN the range of 5-30 in refGene.txt. However the second line in file 1 should NOT match because the first column does not match, which is necessary. If there is a way to include cases when any of the range in file 1 overlaps with any of the range in refGene.txt that would be really helpful. It should also replace the below conditional statements as it would also find all the cases currently described below. Please let me know if my question is unclear. Any help is really appreciated, thanks it advance! (solutions do not have to be in awk) Rubal FILES=/files/*txt for f in $FILES ; do awk ' BEGIN { FS = "\t"; } FILENAME == ARGV[1] { pair[ $1, $2, $3 ] = 1; next; } { if ( pair[ $3, $5, $6 ] == 1 ) { print $13; } } ' $(basename $f) /files/refGene.txt > /files/results/$(basename $f) ; done

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  • Treetop basic parsing and regular expression usage

    - by ucint
    I'm developing a script using the ruby Treetop library and having issues working with its syntax for regex's. First off, many regular expressions that work in other settings dont work the same in treetop. This is my grammar: (myline.treetop) grammar MyLine rule line string whitespace condition end rule string [\S]* end rule whitespace [\s]* end rule condition "new" / "old" / "used" end end This is my usage: (usage.rb) require 'rubygems' require 'treetop' require 'polyglot' require 'myline' parser = MyLineParser.new p parser.parse("randomstring new") This should find the word new for sure and it does! Now I wont to extend it so that it can find new if the input string becomes "randomstring anotherstring new yetanother andanother" and possibly have any number of strings followed by whitespace (tab included) before and after the regex for rule condition. In other words, if I pass it any sentence with the word "new" etc in it, it should be able to match it. So let's say I change my grammar to: rule line string whitespace condition whitespace string end Then, it should be able to find a match for: p parser.parse("randomstring new anotherstring") So, what do I have to do to allow the string whitespace to be repeated before and after condition? If I try to write this: rule line (string whitespace)* condition (whitespace string)* end , it goes in an infinite loop. If i replace the above () with [], it returns nil In general, regex's return a match when i use the above, but treetop regex's dont. Does anyone have any tips/points on how to go about this? Plus, since there isn't much documentation for treetop and the examples are either too trivial or too complex, is there anyone who knows a more thorough documentation/guide for treetop?

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  • Link click does nothing after ajax switching?

    - by Neil
    An odd case I'm trying to figure out here. I'm trying to design a mailbox system, and making some of the options ajax-y. Here's the scenario: We have a page with 2 tabs, inbox and compose. Inbox is a essentially a list of links of the form mailbox.php?msg=xxx. Clicking on the inbox or compose tabs does an ajax switch. So, let's say we're on an message page: mailbox.php?msg=123 I click on "compose" - it ajax switches to a compose form. I change my mind, click on "inbox" - it goes back to a list of messages. Note, the url has not changed at this point (all has been done through ajax). I click on the same message as before. It should go back into that message. However, nothing happens! The url it should go to (mailbox.php?msg=123) IS the url showing in the address bar, but, due to the earlier ajax activity, it's showing the inbox. Thoughts on how to resolve this? And, out of curiosity, an explanation? Normally, clicking on a link that takes you to a page you're already on will reload the page. Thanks!

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  • How can I print a web page on a server?

    - by Gavin Schultz
    Suppose I develop a web page using the cool Google visualization API, and it does everything the user wants. They can the parameters, look at the graphs, and print the page to get a reasonable-looking report. All good. Now suppose I want to do the same thing server-side. For example, say we need a set of report generated at a specific time of day, printed to a PDF and emailed to a manager. It's not a user-initiated action, so we don't have a user's browser or their printer. We have a URL that would render the report if we had a browser, and that's it. Is there a good way to do this server-side? Is this just foolish? Has anyone done anything like that before? Do any of the major browsers have APIs that might provide such functionality? Keep in mind too that it's not just static HTML; probably javascript will be running first to shift the DOM around. I know we could implement a whole different reporting engine on the server side to do this, but that will (a) generate reports that look a bit different, and (b) require me to build/maintain two sets of functionality. Instead, I'd be happy if I could just render the page / pages I want in an invisible server-side browser and print it to a PDF (let's mostly ignore that step - I know any number of PDF printer drivers that could do this). I don't really want to do it ugly either - i.e. by starting a browser process and then sending keystrokes directly to the window either - that's just bound to fall apart with a slight nudge. The only related question I found had an answer like that. Any advice appreciated!

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  • ECM (Niche Vs Mass Market)

    - by Luj Reyes
    Hi Everyone, I recently started a little company with a couple of guys. Ours is the typical startup, a lot of ideas, dreams, talent and work hours :P. Our initial business plan was to develop a DM (Document Manager) with several features found on DropBox and other tools but with a big differentiator. Then we got in the team this Business Guy (I must say that several of us could be called 'Business Guys' but we are mainly hackers, he is just Another 'Networking Guy'), and along with him came this market analysis for a DM aimed at a very specific and narrow niche. We have many elements to believe in his market study and the idea is the classic "The market is X million, so if we grab a 10%...", and the market is really there to grab because all big providers deemed it too little and fled, let's say that the market is 5 million USD and demand very specific features. If we decide to go for this niche product we face a sales cycle of about 7 months, and the main goal of these revenue is to develop more ambitious projects. (Institutional VC is out of the question if you want to keep a marginal ownership of your company in my country). The only overlap between the niche and the mass market product features is the ability to store documents; everything else requires that we focus all of our efforts towards one or the other. I've studied a lot about the differences between Mass and Niche Markets, but I want to hear from people with actual experience. So everything comes down to this: If you have a really “saleable” idea what is the right thing to do: to go for the niche or go for the big prize and target primarily the mass market? Thanks for your input

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  • Code bacteria: evolving mathematical behavior

    - by Stefano Borini
    It would not be my intention to put a link on my blog, but I don't have any other method to clarify what I really mean. The article is quite long, and it's in three parts (1,2,3), but if you are curious, it's worth the reading. A long time ago (5 years, at least) I programmed a python program which generated "mathematical bacteria". These bacteria are python objects with a simple opcode-based genetic code. You can feed them with a number and they return a number, according to the execution of their code. I generate their genetic codes at random, and apply an environmental selection to those objects producing a result similar to a predefined expected value. Then I let them duplicate, introduce mutations, and evolve them. The result is quite interesting, as their genetic code basically learns how to solve simple equations, even for values different for the training dataset. Now, this thing is just a toy. I had time to waste and I wanted to satisfy my curiosity. however, I assume that something, in terms of research, has been made... I am reinventing the wheel here, I hope. Are you aware of more serious attempts at creating in-silico bacteria like the one I programmed? Please note that this is not really "genetic algorithms". Genetic algorithms is when you use evolution/selection to improve a vector of parameters against a given scoring function. This is kind of different. I optimize the code, not the parameters, against a given scoring function.

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  • Maintaining a pool of DAO Class instances vs doing new operator

    - by Fazal
    we have been trying to benchmark our application performance in multiple way for sometime now. I always believed that object creation in java using Class.newInstance() was not slow (at least after 1.4 version of java). But we anyways did a test to use newInstance method vs mainitain an object pool of 1000 objects. We did about 200K iterations of loading data from DB using JDBC and populating these objects. I was amazed (even shocked) to see that newInstance code compared to object pool code was almost 10 times slower. These objects represent tables with about 50 fields and all string type. Can someone share there thoughts on this issue as now I am more confused if object pooling of atleast some DAO instances is a better option. The pool size as I see right now should be large enough to meet size of average requests. There is a flip side as my memory footprint will go up but I am beginning to wonder if this kind of idea makes sense atleast for some of the DAO entities representing tables of about 50 or more columns Please share your ideas and let me know if this has been tried by someone or am I missing some point here

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  • Help needed in grokking password hashes and salts

    - by javafueled
    I've read a number of SO questions on this topic, but grokking the applied practice of storing a salted hash of a password eludes me. Let's start with some ground rules: a password, "foobar12" (we are not discussing the strength of the password). a language, Java 1.6 for this discussion a database, postgreSQL, MySQL, SQL Server, Oracle Several options are available to storing the password, but I want to think about one (1): Store the password hashed with random salt in the DB, one column Found on SO and elsewhere is the automatic fail of plaintext, MD5/SHA1, and dual-columns. The latter have pros and cons MD5/SHA1 is simple. MessageDigest in Java provides MD5, SHA1 (through SHA512 in modern implementations, certainly 1.6). Additionally, most RDBMSs listed provide methods for MD5 encryption functions on inserts, updates, etc. The problems become evident once one groks "rainbow tables" and MD5 collisions (and I've grokked these concepts). Dual-column solutions rest on the idea that the salt does not need to be secret (grok it). However, a second column introduces a complexity that might not be a luxury if you have a legacy system with one (1) column for the password and the cost of updating the table and the code could be too high. But it is storing the password hashed with a random salt in single DB column that I need to understand better, with practical application. I like this solution for a couple of reasons: a salt is expected and considers legacy boundaries. Here's where I get lost: if the salt is random and hashed with the password, how can the system ever match the password? I have theory on this, and as I type I might be grokking the concept: Given a random salt of 128 bytes and a password of 8 bytes ('foobar12'), it could be programmatically possible to remove the part of the hash that was the salt, by hashing a random 128 byte salt and getting the substring of the original hash that is the hashed password. Then re hashing to match using the hash algorithm...??? So... any takers on helping. :) Am I close?

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  • What is the best way to extend restful_authentication/AuthLogic to support lazy logins by an anonymo

    - by Kevin Elliott
    I'm building an iPhone application that talks to a Ruby on Rails backend. The Ruby on Rails application will also service web users. The restful_authentication plugin is an excellent way to provide quick and customizable user authentication. However, I would like users of the iPhone application to have an account created automatically by the phone's unique identifier ([[UIDevice device] uniqueIdentifier]) stored in a new column. Later, when users are ready to create a username/password, the account will be updated to contain the username and password, leaving the iPhone unique identifier intact. Users should not be able to access the website until they've setup their username/password. They can however, use the iPhone application, since the application can authenticate itself using it's identifier. What is the best way to modify restful_authentication to do this? Create a plugin? Or modify the generated code? What about alternative frameworks, such as AuthLogic. What is the best way to allow iPhones to get a generated auth token locked to their UUID's, but then let the user create a username/password later?

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  • C# WebClient OpenRead url

    - by Octopus-Paul
    So i have this program that fetch a page using a short link (I used Google url shortener) to build my example i used the code from Using WebClient in C# is there a way to get the URL of a site after being redirected? using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; using System.Net; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { MyWebClient client = new MyWebClient(); client.OpenRead("http://tinyurl.com/345yj7x"); Uri uri = client.ResponseUri; Console.WriteLine(uri.AbsoluteUri); Console.Read(); } } class MyWebClient : WebClient { Uri _responseUri; public Uri ResponseUri { get { return _responseUri; } } protected override WebResponse GetWebResponse(WebRequest request) { WebResponse response = base.GetWebResponse(request); _responseUri = response.ResponseUri; return response; } } } I do not understant a thing: when i do client.OpenRead("http://tinyurl.com/345yj7x"); this downloads the page that the url points to? If this method downloads the page, I need something to get me only the url, so if there a method to get only some headers, or only the url please let me know.

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  • Finding usage of jQuery UI in a big ugly codebase

    - by Daniel Magliola
    I've recently inherited the maintenance of a big, ugly codebase for a production website. Poke your eyes out ugly. And though it's big, it's mostly PHP code, it doesn't have much JS, besides a few "ajaxy" things in the UI. Our main current problem is that the site is just too heavy. Homepage weighs in at 1.6 Mb currently, so I'm trying to clean some stuff out. One of the main wasters is that every single page includes the jQuery UI library, but I don't think it's used at all. It's definitely not being used in the homepage and in most pages, so I want to only include the where necessary. I'm not really experienced with jQuery, i'm more of a Prototype guy, so I'm wondering. Is there anything I could search for that'd let me know where jQuery UI is being used? What i'm looking for is "common strings", component names, etc For example, if this was scriptaculous, i'd look for things like "Draggable", "Effect", etc. Any suggestions for jQuery UI? (Of course, if you can think of a more robust way of removing the tag from pages that don't use it without breaking everything, I'd love to hear about it) Thanks!! Daniel

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  • Rails: Oracle constraint violation

    - by justinbach
    I'm doing maintenance work on a Rails site that I inherited; it's driven by an Oracle database, and I've got access to both development and production installations of the site (each with its own Oracle DB). I'm running into an Oracle error when trying to insert data on the production site, but not the dev site: ActiveRecord::StatementInvalid (OCIError: ORA-00001: unique constraint (DATABASE_NAME.PK_REGISTRATION_OWNERSHIP) violated: INSERT INTO registration_ownerships (updated_at, company_ownership_id, created_by, updated_by, registration_id, created_at) VALUES ('2006-05-04 16:30:47', 3, NULL, NULL, 2920, '2006-05-04 16:30:47')): /usr/local/lib/ruby/gems/1.8/gems/activerecord-oracle-adapter-1.0.0.9250/lib/active_record/connection_adapters/oracle_adapter.rb:221:in `execute' app/controllers/vendors_controller.rb:94:in `create' As far as I can tell (I'm using Navicat as an Oracle client), the DB schema for the dev site is identical to that of the live site. I'm not an Oracle expert; can anyone shed light on why I'd be getting the error in one installation and not the other? Incidentally, both dev and production registration_ownerships tables are populated with lots of data, including duplicate entries for country_ownership_id (driven by index PK_REGISTRATION_OWNERSHIP). Please let me know if you need more information to troubleshoot. I'm sorry I haven't given more already, but I just wasn't sure which details would be helpful.

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