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  • C# - Which is more efficient and thread safe? static or instant classes?

    - by Soni Ali
    Consider the following two scenarios: //Data Contract public class MyValue { } Scenario 1: Using a static helper class. public class Broker { private string[] _userRoles; public Broker(string[] userRoles) { this._userRoles = userRoles; } public MyValue[] GetValues() { return BrokerHelper.GetValues(this._userRoles); } } static class BrokerHelper { static Dictionary<string, MyValue> _values = new Dictionary<string, MyValue>(); public static MyValue[] GetValues(string[] rolesAllowed) { return FilterForRoles(_values, rolesAllowed); } } Scenario 2: Using an instance class. public class Broker { private BrokerService _service; public Broker(params string[] userRoles) { this._service = new BrokerService(userRoles); } public MyValue[] GetValues() { return _service.GetValues(); } } class BrokerService { private Dictionary<string, MyValue> _values; private string[] _userRoles; public BrokerService(string[] userRoles) { this._userRoles = userRoles; this._values = new Dictionary<string, MyValue>(); } public MyValue[] GetValues() { return FilterForRoles(_values, _userRoles); } } Which of the [Broker] scenarios will scale best if used in a web environment with about 100 different roles and over a thousand users. NOTE: Feel free to sugest any alternative approach.

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  • How to access this data in PHP?

    - by George Edison
    Okay. Now I give up. I have been playing with this for hours. I have a variable name $data. The variable contains these contents: array ( 'headers' => array ( 'content-type' => 'multipart/alternative; boundary="_689e1a7d-7a0a-442a-bd6c-a1fb1dc2993e_"', ), 'ctype_parameters' => array ( 'boundary' => '_689e1a7d-7a0a-442a-bd6c-a1fb1dc2993e_', ), 'parts' => array ( 0 => stdClass::__set_state(array( 'headers' => array ( 'content-type' => 'text/plain; charset="iso-8859-1"', 'content-transfer-encoding' => 'quoted-printable', ), 'ctype_primary' => 'text', )), ), ) I removed some non-essential data. I want to access the headers value (on the second line above) - simple: $data->headers I want to access the headers value (on the fourteenth line after the stdClass:: stuff) - how? How can I possibly access the values within the stdClass::__set_state section? I tried var_export($data->parts); but all I get is NULL

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  • Node.js fetching Twitter Streaming API - EADDRNOTAVAIL

    - by Jordan Scales
    I have the following code written in node.js to access to the Twitter Streaming API. If I curl the URL below, it works. However, I cannot get it to work with my code. var https = require('https'); https.request('https://USERNAME:[email protected]/1.1/statuses/sample.json', function(res) { res.on('data', function(chunk) { var d = JSON.parse(chunk); console.log(d); }); }); But I receive the following node.js:201 throw e; // process.nextTick error, or 'error' event on first tick ^ Error: connect EADDRNOTAVAIL at errnoException (net.js:642:11) at connect (net.js:525:18) at Socket.connect (net.js:589:5) at Object.<anonymous> (net.js:77:12) at new ClientRequest (http.js:1073:25) at Object.request (https.js:80:10) at Object.<anonymous> (/Users/jordan/Projects/twitter-stream/app.js:3:7) at Module._compile (module.js:441:26) at Object..js (module.js:459:10) at Module.load (module.js:348:31) If anyone can offer an alternative solution, or explain to me why this doesn't work, I would be very grateful.

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  • Problem sending email with Codeigniter - Headers sent in the message body

    - by Brian
    Having a strange issue with the email class in codeigniter. When I send email directly to my gmail account email address, it works fine. However if I send email to a different email address and use POP3 to import that email address into gmail, then for some reason all the headers are included in the message. Here's the code for sending the email: $this->email->clear(); $config['mailtype'] = "html"; $this->email->initialize($config); $this->email->set_newline("\r\n"); $this->email->from('[email protected]', 'Website'); $this->email->to('[email protected]'); $this->email->message($message); Here's what arrives in my inbox when the email is sent to an account which is imported into gmail via POP3: Date: Fri, 7 Jan 2011 15:07:04 +0000 From: "Website" <[email protected]> Reply-To: "[email protected]" <[email protected]> X-Sender: [email protected] X-Mailer: CodeIgniter X-Priority: 3 (Normal) Message-ID: <[email protected]> Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="B_ALT_4d272c1835c46" This is a multi-part message in MIME format. Your email application may not support this format. --B_ALT_4d272c1835c46 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit this is the email message content --B_ALT_4d272c1835c46 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable <html> <body> <p>this is the email message content </p> </body> </html> --B_ALT_4d272c1835c46--

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  • Does NHibernate LINQ support ToLower() in Where() clauses?

    - by Daniel T.
    I have an entity and its mapping: public class Test { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual string Description { get; set; } } public class TestMap : EntityMap<Test> { public TestMap() { Id(x => x.Id); Map(x => x.Name); Map(x => x.Description); } } I'm trying to run a query on it (to grab it out of the database): var keyword = "test" // this is coming in from the user keyword = keyword.ToLower(); // convert it to all lower-case var results = session.Linq<Test> .Where(x => x.Name.ToLower().Contains(keyword)); results.Count(); // execute the query However, whenever I run this query, I get the following exception: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index Am I right when I say that, currently, Linq to NHibernate does not support ToLower()? And if so, is there an alternative that allows me to search for a string in the middle of another string that Linq to NHibernate is compatible with? For example, if the user searches for kap, I need it to match Kapiolani, Makapuu, and Lapkap.

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  • Forcing file redirection on x64 for a 32-bit application

    - by Paul Alexander
    The silent redirection of 64-bit system files to their 32-bit equivalents can be turned off and reverted with Wow64DisableWow64FsRedirection and Wow64RevertWow64FsRedirection. We use this for certain file identity checks in our application. The problem is that in performing some of theses tasks, we might call a framework or Windows API in a DLL that has not yet been loaded. If redirection is enabled at that time, the wrong version of the dll may be loaded resulting in a XXX is not a valid Win32 application error. I've identified the few API calls in question and what I'd like to do force the redirection on for the duration of that call then revert it back - just the opposite of the provided Win32 APIs. Unfortunately these calls do not provide any sort of WOW64 compatibility flag like some of the registry methods do. The obvious alternative is to use Wow64EnableWow64FsRedirection, pass TRUE for Wow64FsEanbledRedirection. However there are a variety of warnings about the use of this method and a note that it is not compatible with Disable/Revert combo methods that have replaced it. Is there a safe way to force redirection on for a give Win32 call? The docs state the redirection is thread specific so I've considered spinning up a new thread for the specific call with appropriate locks and waits, but I was hoping for a simpler solution.

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  • When virtual inheritance IS a good design?

    - by 7vies
    EDIT3: Please be sure to clearly understand what I am asking before answering (there are EDIT2 and lots of comments around). There are (or were) many answers which clearly show misunderstanding of the question (I know that's also my fault, sorry for that) Hi, I've looked over the questions on virtual inheritance (class B: public virtual A {...}) in C++, but did not find an answer to my question. I know that there are some issues with virtual inheritance, but what I'd like to know is in which cases virtual inheritance would be considered a good design. I saw people mentioning interfaces like IUnknown or ISerializable, and also that iostream design is based on virtual inheritance. Would those be good examples of a good use of virtual inheritance, is that just because there is no better alternative, or because virtual inheritance is the proper design in this case? Thanks. EDIT: To clarify, I'm asking about real-life examples, please don't give abstract ones. I know what virtual inheritance is and which inheritance pattern requires it, what I want to know is when it is the good way to do things and not just a consequence of complex inheritance. EDIT2: In other words, I want to know when the diamond hierarchy (which is the reason for virtual inheritance) is a good design

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  • How to avoid using this in a constructor

    - by Paralife
    I have this situation: interface MessageListener { void onMessageReceipt(Message message); } class MessageReceiver { MessageListener listener; public MessageReceiver(MessageListener listener, other arguments...) { this.listener = listener; } loop() { Message message = nextMessage(); listener.onMessageReceipt(message); } } and I want to avoid the following pattern: (Using the this in the Client constructor) class Client implements MessageListener { MessageReceiver receiver; MessageSender sender; public Client(...) { receiver = new MessageReceiver(this, other arguments...); sender = new Sender(...); } . . . @Override public void onMessageReceipt(Message message) { if(Message.isGood()) sender.send("Congrtulations"); else sender.send("Boooooooo"); } } The reason why i need the above functionality is because i want to call the sender inside the onMessageReceipt() function, for example to send a reply. But I dont want to pass the sender into a listener, so the only way I can think of is containing the sender in a class that implements the listener, hence the above resulting Client implementation. Is there a way to achive this without the use of 'this' in the constructor? It feels bizare and i dont like it, since i am passing myself to an object(MessageReceiver) before I am fully constructed. On the other hand, the MessageReceiver is not passed from outside, it is constructed inside, but does this 'purifies' the bizarre pattern? I am seeking for an alternative or an assurance of some kind that this is safe, or situations on which it might backfire on me.

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  • Forms Auth: have different credentials for a subdirectory?

    - by Fyodor Soikin
    My website has forms authentication, and all is well. Now I want to create a subdirectory and have it also password-protected, but! I need the subdirectory to use a completely different set of logins/passwords than the whole website uses. Say, for example, I have users for the website stored in the "Users" table in a database. But for the subdirectory, I want the users to be taken from the "SubdirUsers" table. Which probably has a completely different structure. Consequently, I need the logins to be completely parallel, as in: Logging into the whole website does not make you logged into the subdirectory as well Clicking "logout" on the whole website does not nullify your login in the subdirectory And vice versa I do not want to create a separate virtual application for the subdirectory, because I want to share all libraries, user controls, as well as application state and cache. In other words, it has to be the same application. I also do not want to just add a flag to the "Users" table indicating whether this is a whole website user or the subdirectory user. User lists have to come from different sources. For now, the only option that I see is to roll my own Forms Auth for the subdirectory. Anybody can propose a better alternative?

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  • How to make Facebook Authentication from Silverlight secure?

    - by SondreB
    I have the following scenario I want to complete: Website running some HTTP(S) services that returns data for a user. Same website is additionally hosting a Silverlight 4 app which calls these services. The Silverlight app is integrating with Facebook using the Facebook Developer Toolkit (http://facebooktoolkit.codeplex.com/). I have not fully decided whether I want Facebook-integration to be a "opt-in" option such as Spotify, or if I want to "lock" down my service with Facebook-only authentication. That's another discussion. How do I protect my API Key and Secret that I receive from Facebook in a Silverlight app? To me it's obvious that this is impossible as the code is running on the client, but is there a way I can make it harder or should I just live with the fact that third parties could potentially "act" as my own app? Using the Facebook Developer Toolkit, there is a following C# method in Silverlight that is executed from the JavaScript when the user has fully authenticated with Facebook using the Facebook Connect APIs. [ScriptableMember] public void LoggedIn(string sessionKey, string secret, int expires, long userId) { this.SessionKey = sessionKey; this.UserId = userId; Obvious the problem here is the fact that JavaScript is injection the userId, which is nothing but a simple number. This means anyone could potentially inject a different userId in JavaScript and have my app think it's someone else. This means someone could hijack the data within the services running on my website. The alternative that comes to mind is authenticating the users on my website, this way I'm never exposing any secrets and I can return an auth-cookie to the users after the initial authentication. Though this scenario doesn't work very well in an out-of-browser scenario where the user is running the Silverlight app locally and not from my website.

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  • best way to switch between secure and unsecure connection without bugging the user

    - by Brian Lang
    The problem I am trying to tackle is simple. I have two pages - the first is a registration page, I take in a few fields from the user, once they submit it takes them to another page that processes the data, stores it to a database, and if successful, gives a confirmation message. Here is my issue - the data from the user is sensitive - as in, I'm using an https connection to ensure no eavesdropping. After that is sent to the database, I'd like on the confirmation page to do some nifty things like Google Maps navigation (this is for a time reservation application). The problem is by using the Google Maps api, I'd be linking to items through a unsecure source, which in turn prompts the user with a nasty warning message. I've browsed around, Google has an alternative to enterprise clients, but it costs $10,000 a year. What I am hoping is to find a workaround - use a secure connection to take in the data, and after it is processed, bring them to a page that isn't secure and allows me to utilize the Google Maps API. If any of you have a Netflix account you can see exactly what I would like to do when you sign-in, it is a secure page, which then takes you to your account / queue, on an unsecure page. Any suggestions? Thanks!

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  • JConsole does not connect when a program is waiting for a console input

    - by Calm Storm
    Hi, I have a problem similar to the one mentioned here. I have a program which launches a selenium browser and refreshes it every 2 seconds. My idea here was to monitor the memory usage of my application as the page is being hit. This console program does a "System.in.read" and when a user presses enter key, this stops the browser refresh thread. I run the program and it runs as I would expect it to. But when I fire jconsole and attach it to the process, it looks like jconsole waits forever to attach. This is because of the "System.in.read", apparently as shown in the JConsole source. In my code it makes perfect sense for me to terminte the browser when user presses something so is there any alternative available at all ? (Posted code sample below) package com.ekanathk; import java.util.ArrayList; import java.util.List; import org.junit.Test; public class MultiThread { @Test public void testSimple() throws Exception { List<Integer> x = new ArrayList<Integer>(); for(int i = 0; i < 1000; i++) { x.add(i); } System.out.print("Press Enter to stop (try attach a jconsole now...."); System.in.read(); } } The problem here seems to be that any System.in.read (either in Main thread or any threads) seems to completely block jconsole. I guess the problem essentially boils down to multiple threads requesting system inputs at the same time? Is there a solution ?

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  • What is the right approach to checksumming UDP packets

    - by mr.b
    I'm building UDP server application in C#. I've come across a packet checksum problem. As you probably know, each packet should carry some simple way of telling receiver if packet data is intact. Now, UDP already has 2-byte checksum as part of header, which is optional, at least in IPv4 world. Alternative method is to have custom checksum as part of data section in each packet, and to verify it on receiver. My question boils down to: is it better to rely on (optional) checksum in UDP packet header, or to make a custom checksum implementation as part of packet data section? Perhaps the right answer depends on circumstances (as usual), so one circumstance here is that, even though code is written and developed in .NET on Windows, it might have to run under platform-independent Mono.NET, so eventual solution should be compatible with other platforms. I believe that custom checksum algorithm would be easily portable, but I'm not so sure about the first one. Any thoughts? Also, shouts about packet checksumming in general are welcome.

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  • How can I choose different hints for different joins for a single table in a query hint?

    - by RenderIn
    Suppose I have the following query: select * from A, B, C, D where A.x = B.x and B.y = C.y and A.z = D.z I have indexes on A.x and B.x and B.y and C.y and D.z There is no index on A.z. How can I give a hint to this query to use an INDEX hint on A.x but a USE_HASH hint on A.z? It seems like hints only take the table name, not the specific join, so when using a single table with multiple joins I can only specify a single strategy for all of them. Alternative, suppose I'm using a LEADING or ORDERED hint on the above query. Both of these hints only take a table name as well, so how can I ensure that the A.x = B.x join takes place before the A.z = D.z one? I realize in this case I could list D first, but imagine D subsequently joins to E and that the D-E join is the last one I want in the entire query. A third configuration -- Suppose I want the A.x join to be the first of the entire query, and I want the A.z join to be the last one. How can I use a hint to have a single join from A to take place, followed by the B-C join, and the A-D join last?

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  • Too many false positives when using FxCop.

    - by mark
    Dear ladies and sirs. We are using FxCop and it generates too many false positives to our liking. For instance, if a private method is invoked using reflection, then this method is reported as potentially unused - understandable and we suppress this warning explicitly using the SuppressMessage attribute. However, FxCop reports the same warning for the methods invoked from that method, which we already suppressed warnings about. This is stupid and generates too much noise. There are also false reports on member variables used in these methods. Also, there are problems with generic types (I even saw something about it in MS connect). Anyway, I am wondering if anyone knows whether Microsoft is going to upgrade FxCop, because it seems to be stuck in version 1.36 for a long time. BTW, I we do not use StyleCop, because it is way too picky and we just do not have the time to examine all the zillion messages in order to suppress them all. Besides, the StyleCop report seem to augment, rather than replace FxCop. Maybe anyone can suggest a good alternative to FxCop? We are using VS2008 pro. Thanks.

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  • Understanding CSRF - Simple Question

    - by byronh
    I know this might make me seem like an idiot, I've read everything there is to read about CSRF and I still don't understand how using a 'challenge token' would add any sort of prevention. Please help me clarify the basic concept, none of the articles and posts here on SO I read seemed to really explicitly state what value you're comparing with what. From OWASP: In general, developers need only generate this token once for the current session. After initial generation of this token, the value is stored in the session and is utilized for each subsequent request until the session expires. If I understand the process correctly, this is what happens. I log in at http://example.com and a session/cookie is created containing this random token. Then, every form includes a hidden input also containing this random value from the session which is compared with the session/cookie upon form submission. But what does that accomplish? Aren't you just taking session data, putting it in the page, and then comparing it with the exact same session data? Seems like circular reasoning. These articles keep talking about following the "same-origin policy" but that makes no sense, because all CSRF attacks ARE of the same origin as the user, just tricking the user into doing actions he/she didn't intend. Is there any alternative other than appending the token to every single URL as a query string? Seems very ugly and impractical, and makes bookmarking harder for the user.

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  • SQL Server Multi-statement UDF - way to store data temporarily required

    - by Kharlos Dominguez
    Hello, I have a relatively complex query, with several self joins, which works on a rather large table. For that query to perform faster, I thus need to only work with a subset of the data. Said subset of data can range between 12 000 and 120 000 rows depending on the parameters passed. More details can be found here: http://stackoverflow.com/questions/3054843/sql-server-cte-referred-in-self-joins-slow As you can see, I was using a CTE to return the data subset before, which caused some performance problems as SQL Server was re-running the Select statement in the CTE for every join instead of simply being run once and reusing its data set. The alternative, using temporary tables worked much faster (while testing the query in a separate window outside the UDF body). However, when I tried to implement this in a multi-statement UDF, I was harshly reminded by SQL Server that multi-statement UDFs do not support temporary tables for some reason... UDFs do allow table variables however, so I tried that, but the performance is absolutely horrible as it takes 1m40 for my query to complete whereas the the CTE version only took 40minutes. I believe the table variables is slow for reasons listed in this thread: http://stackoverflow.com/questions/1643687/table-variable-poor-performance-on-insert-in-sql-server-stored-procedure Temporary table version takes around 1 seconds, but I can't make it into a function due to the SQL Server restrictions, and I have to return a table back to the caller. Considering that CTE and table variables are both too slow, and that temporary tables are rejected in UDFs, What are my options in order for my UDF to perform quickly? Thanks a lot in advance.

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  • Does HttpListener work well on Mono?

    - by billpg
    Hi everyone. I'm looking to write a small web service to run on a small Linux box. I prefer to code in C#, so I'm looking to use Mono. I don't want the overhead of running a full web server or Mono's version of ASP.NET. I'm thinking of having a single process with a thread dealing with each client connection. Shared memory between threads instead of a database. I've read a little on Microsoft's version of HttpListener and how it works with the Http.sys driver. Alas, Mono's documentation on this class is just the automated class interface with no discussion of how it works under the hood. (Linux doesn't have Http.sys, so I imagine it's implemented substantially differently.) Could anyone point me towards some resources discussing this module please? Many thanks, Bill, billpg.com (A little background to my question for the interested.) Some time ago, I asked this question, interested in keeping a long conversation open with lots of back-and-forth. I had settled on designing my own ad-hoc protocol, but people I spoke to really wanted a REST interface, even at the cost of the "Okay, send your command now" signal. So, I wondered about running ASP.NET on a Linux/Mono server, but stumbled upon HttpListener. This seemed ideal, as each "conversation" could run in a separate thread. The thread that calls HttpListener in a loop can look for which thread each incomming connection is for and pass the reference to that thread. The alternative for an ASP.NET driven service, would be to have the ASPX code pick up the state from a database, and write back the new state when it finishes. Yes, it would work, but that's a lot of overhead.

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  • Working for free

    - by truncate
    Finances are making me take an extended period off of my college education. In my current state, I don't feel fully qualified to be employed by an iPhone software company. While I work on getting things back together, I'd like to try an work for a software company for free in my local area (I'm going to college out of state and have to move back as well). The economy has forced employers to be very picky about who they hire, if any at all. Since I'd like to continue refining my abilities, I was wondering on what the consensus is on working for free. It can't be considered an internship, as I would no longer be in school..., I guess an apprenticeship is more appropriate. Like I said, I don't think I'm qualified to be paid for my services, and I don't want to be. I just don't know how to ask, or if it's even appropriate to ask them to show me how to develop software in the real world. My thinking is that they would be willing to get some work done for free and if I prove myself, they could hire me. If not, there was no major loss. They get some free development, and lose a bit of time helping show me the ropes. I get either a job, or valuable experience that I need. The other alternative is that I try to work out things by myself on the iPhone platform, but that sounds terrifying. I appreciate any input the community has to offer.

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  • SIGABRT Issues with UIApplication_TVOut and MPVideoView - is there another way??

    - by user365920
    Hi there, I am due to do a demo in a week of an app which i have been working on for a company - until now, i have been using code taken from this useful tutorial here The problem is that this no longer seems to be working - causing a SIGABRT inside of the following (see initWithVideoView): - (void) startTVOut; { // you need to have a main window already open when you call start if (!tvoutWindow) { deviceWindow = [self keyWindow]; MPVideoView *vidView = [[MPVideoView alloc] initWithFrame: CGRectZero]; **tvoutWindow = [[MPTVOutWindow alloc] initWithVideoView:vidView];** [tvoutWindow makeKeyAndVisible]; tvoutWindow.userInteractionEnabled = NO; mirrorView = [[UIImageView alloc] initWithFrame: [[UIScreen mainScreen] bounds]]; [self reformatTVOutOrientation]; mirrorView.center = vidView.center; [vidView addSubview: mirrorView]; [deviceWindow makeKeyAndVisible]; [NSThread detachNewThreadSelector:@selector(updateLoop) toTarget:self withObject:nil]; } } Can anyone help at all??? This was all working fine, but seems to have stopped working recently - none of my code has changed, so assuming Apple have removed that API (yes, i know it was a private API in the first place, so im not moaning!) Just need to know if there is an alternative way of displaying the contents of my iPhone screen in my app... Many thanks in advance!

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  • Obtaining touch location for a uiscrollview touch

    - by LOSnively
    I have a uiscrollview as an element of a uiscrollviewcontroller, along with other view objects. The image scrolls and zooms as expected, when the scrollView is the top subview. However, I also need to get the screen location of the touch, in particular when there is no scroll action. (I understand the location may change during a scroll, but that's not important.) I haven't found a way to do that. In the scrollviewcontroller implementation I have customized all of the standard methods that should do this: "touchesShouldBegin...", "touchesBegan:...", "touchesEnded:...", and so on. As far as I can tell, none of these are being called during a touch event when the scrollView is the top subview. I've tried setting the delayContentTouches property to both YES and NO, and that doesn't seem to make a difference. As an alternative, I've tried putting a UIView as the top subview and then tried passing the touches to the now underlying scrollView. In this configuration, the standard methods are called and I can get the touch location, but I haven't found a mechanism for the touches to be passed to the scrollView so scrolling occurs. Doing something like sending the touch messages to the specific scrollView, or to "super" or just sending them to nextResponder doesn't do it. It seems I can make the scroll work or find the location of the touch but not both, depending on what the "top" subview is. I suspect this is trivial, but after two weeks of struggling, it's time to eat my embarrassment for not being able to do this seemingly simplest of things. I've read all of the related questions here on stackoverflow, tried most if not all of the suggestions, and so far, nothing has worked. I've looked through the various links and references suggested by the answers, including Apple's documentation, but none have pointed out the gap in my understanding. Any ideas would be appreciated.

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  • How to recalculate all-pairs shorthest paths on-line if nodes are getting removed?

    - by Pavel Shved
    Latest news about underground bombing made me curious about the following problem. Assume we have a weighted undirected graph, nodes of which are sometimes removed. The problem is to re-calculate shortest paths between all pairs of nodes fast after such removals. With a simple modification of Floyd-Warshall algorithm we can calculate shortest paths between all pairs. These paths may be stored in a table, where shortest[i][j] contains the index of the next node on the shortest path between i and j (or NULL value if there's no path). The algorithm requires O(n³) time to build the table, and eacho query shortest(i,j) takes O(1). Unfortunately, we should re-run this algorithm after each removal. The other alternative is to run graph search on each query. This way each removal takes zero time to update an auxiliary structure (because there's none), but each query takes O(E) time. What algorithm can be used to "balance" the query and update time for all-pairs shortest-paths problem when nodes of the graph are being removed?

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  • What is the 'page lifecycle' of an ASP.NET MVC page, compared to ASP.NET WebForms?

    - by Simon
    What is the 'page lifecycle' of an ASP.NET MVC page, compared to ASP.NET WebForms? I'm tryin to better understand this 'simple' question in order to determine whether or not existing pages I have in a (very) simple site can be easily converted from ASP.NET WebForms. Either a 'conversion' of the process below, or an alternative lifecycle would be what I'm looking for. What I'm currently doing: (yes i know that anyone capable of answering my question already knows all this -- i'm just tryin to get a comparison of the 'lifecycle' so i thought i'd start by filling in what we already all know) Rendering the page: I have a master page which contains my basic template I have content pages that give me named regions from the master page into which I put content. In an event handler for each content page I load data from the database (mostly read-only). I bind this data to ASP.NET controls representing grids, dropdowns or repeaters. This data all 'lives' inside the HTML generated. Some of it gets into ViewState (but I wont go into that too much!) I set properties or bind data to certain items like Image or TextBox controls on the page. The page gets sent to the client rendered as non-reusable HTML. I try to avoid using ViewState other than what the page needs as a minimum. Client side (not using ASP.NET AJAX): I may use JQuery and some nasty tricks to find controls on the page and perform operations on them. If the user selects from a dropdown -- a postback is generated which triggers a C# event in my codebehind. This event may go to the database, but whatever it does a completely newly generated HTML page ends up getting sent back to the client. I may use Page.Session to store key value pairs I need to reuse later So with MVC how does this 'lifecycle' change?

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  • Can Haskell's Parsec library be used to implement a recursive descent parser with backup?

    - by Thor Thurn
    I've been considering using Haskell's Parsec parsing library to parse a subset of Java as a recursive descent parser as an alternative to more traditional parser-generator solutions like Happy. Parsec seems very easy to use, and parse speed is definitely not a factor for me. I'm wondering, though, if it's possible to implement "backup" with Parsec, a technique which finds the correct production to use by trying each one in turn. For a simple example, consider the very start of the JLS Java grammar: Literal: IntegerLiteral FloatingPointLiteral I'd like a way to not have to figure out how I should order these two rules to get the parse to succeed. As it stands, a naive implementation like this: literal = do { x <- try (do { v <- integer; return (IntLiteral v)}) <|> (do { v <- float; return (FPLiteral v)}); return(Literal x) } Will not work... inputs like "15.2" will cause the integer parser to succeed first, and then the whole thing will choke on the "." symbol. In this case, of course, it's obvious that you can solve the problem by re-ordering the two productions. In the general case, though, finding things like this is going to be a nightmare, and it's very likely that I'll miss some cases. Ideally, I'd like a way to have Parsec figure out stuff like this for me. Is this possible, or am I simply trying to do too much with the library? The Parsec documentation claims that it can "parse context-sensitive, infinite look-ahead grammars", so it seems like something like I should be able to do something here.

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  • Storing Arbitrary Contact Information in Ruby on Rails

    - by Anthony Chivetta
    Hi, I am currently working on a Ruby on Rails app which will function in some ways like a site-specific social networking site. As part of this, each user on the site will have a profile where they can fill in their contact information (phone numbers, addresses, email addresses, employer, etc.). A simple solution to modeling this would be to have a database column per piece of information I allow users to enter. However, this seems arbitrary and limited. Further, to support allowing users to enter as many phone numbers as they would like requires the addition of another database table and joins. It seems to me that a better solution would be to serialize all the contact information entered by a user into a single field in their row. Since I will never be conditioning a SQL query on this information, such a solution wouldn't be any less efficient. Ideally, I would like to use a vCard as my serialization format. vCards are the standard solution to storing contact information across the web, and reusing tested solutions is a Good Thing. Alternative serialization formats would include simply marshaling a ruby hash, or YAML. Regardless of serialization format, supporting the reading and updating of this information in a rails-like way seems to be a major implementation challenge. So, here's the question: Has anyone seen this approach used in a rails application? Are there any rails plugins or gems that make such a system easy to implement? Ideally what I would like is an acts_as_vcard to add to my model object that would handle editing the vcard for me and saving it back to the database.

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