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  • C# class can not disguise to be another class because GetType method cannot be override

    - by zinking
    there is a statement in the CLR via C# saying in C#, one class cannot disguise to be another, because GetType is virutal and thus it cannot be override but I think in C# we can still hide the parent implementation of GetType. I must missed something if I hide the base GetType implementation then I can disguise my class to be another class, is that correct? The key here is not whether GetType is virutal or not, the question is can we disguise one class to be another in C# Following is the NO.4 answer from the possible duplicate, so My question is more on this. is this kind of disguise possible, if so, how can we say that we can prevent class type disguise in C# ? regardless of the GetType is virtual or not While its true that you cannot override the object.GetType() method, you can use "new" to overload it completely, thereby spoofing another known type. This is interesting, however, I haven't figured out how to create an instance of the "Type" object from scratch, so the example below pretends to be another type. public class NotAString { private string m_RealString = string.Empty; public new Type GetType() { return m_RealString.GetType(); } } After creating an instance of this, (new NotAString()).GetType(), will indeed return the type for a string. share|edit|flag answered Mar 15 at 18:39 Dr Snooze 213 By almost anything that looks at GetType has an instance of object, or at the very least some base type that they control or can reason about. If you already have an instance of the most derived type then there is no need to call GetType on it. The point is as long as someone uses GetType on an object they can be sure it's the system's implementation, not any other custom definition. – Servy Mar 15 at 18:54 add comment

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  • git rebase without changing commit timestamps

    - by Olivier
    Would it make sense to perform git rebase while preserving the commit timestamps? I believe a consequence would be that the new branch will not necessarily have commit dates chronologically. Is that theoretically possible at all? (e.g. using plumbing commands; just curious here) If it is theoretically possible, then is it possible in practice with rebase, not to change the timestamps? For example, assume I have the following tree: master <jun 2010> | : : : oldbranch <feb 1984> : / oldcommit <jan 1984> Now, if I rebase oldbranch on master, the date of the commit changes from feb 1984 to jun 2010. Is it possible to change that behaviour so that the commit timestamp is not changed? In the end I would thus obtain: oldbranch <feb 1984> / master <jun 2010> | : Would that make sense at all? Is it even allowed in git to have a history where an old commit has a more recent commit as a parent? Edit A crucial question of Von C helped me understand what is going on: when your rebase, the committer's timestamp changes, but not the author's timestamp, which suddenly all makes sense. So my question was actually not precise enough. The answer is that rebase actually doesn't change the author's timestamps (you don't need to do anything for that), which suits me perfectly.

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  • send SMS from WAP page

    - by user217069
    This question is related to sending an SMS from a link in a WAP page? Historically I have used sms: which has worked on SonyEricsson, Nokia and other such 'legacy' devices. An example of the mark-up would be; <a href="sms:0123456789?body=test%20message">send</a> I am aware that i-phone does not allow you to specify the body. If the body tag is present then the device closes the browser and opens the SMS application but does not go as far as taking the user to message creation. As such the following does not really work; <a href="sms:0123456789?body=test%20message">send</a> however, this partially does... in that it takes the user to the editor and selects the recipient. <a href="sms:0123456789">send</a> My tests with Android (HTC desire) cause the message editor to crash (with the above examples). I have managed to get the message editor to open successfully but not managed to pass any details (recipient or message body) using; <a href="sms://0123456789">send</a> Note the :// which is not correct according to the Nokia specs. Has anyone had any more success? Sorry if this is a bit hazy, its probably more of a discussion than a question.

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  • When to choose which machine learning classifier?

    - by LM
    Suppose I'm working on some classification problem. (Fraud detection and comment spam are two problems I'm working on right now, but I'm curious about any classification task in general.) How do I know which classifier I should use? (Decision tree, SVM, Bayesian, logistic regression, etc.) In which cases is one of them the "natural" first choice, and what are the principles for choosing that one? Examples of the type of answers I'm looking for (from Manning et al.'s "Introduction to Information Retrieval book": http://nlp.stanford.edu/IR-book/html/htmledition/choosing-what-kind-of-classifier-to-use-1.html): a. If your data is labeled, but you only have a limited amount, you should use a classifier with high bias (for example, Naive Bayes). [I'm guessing this is because a higher-bias classifier will have lower variance, which is good because of the small amount of data.] b. If you have a ton of data, then the classifier doesn't really matter so much, so you should probably just choose a classifier with good scalability. What are other guidelines? Even answers like "if you'll have to explain your model to some upper management person, then maybe you should use a decision tree, since the decision rules are fairly transparent" are good. I care less about implementation/library issues, though. Also, for a somewhat separate question, besides standard Bayesian classifiers, are there 'standard state-of-the-art' methods for comment spam detection (as opposed to email spam)? [Not sure if stackoverflow is the best place to ask this question, since it's more machine learning than actual programming -- if not, any suggestions for where else?]

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  • How to hand-over a TCP listening socket with minimal downtime?

    - by Shtééf
    While this question is tagged EventMachine, generic BSD-socket solutions in any language are much appreciated too. Some background: I have an application listening on a TCP socket. It is started and shut down with a regular System V style init script. My problem is that it needs some time to start up before it is ready to service the TCP socket. It's not too long, perhaps only 5 seconds, but that's 5 seconds too long when a restart needs to be performed during a workday. It's also crucial that existing connections remain open and are finished normally. Reasons for a restart of the application are patches, upgrades, and the like. I unfortunately find myself in the position that, every once in a while, I need to do this kind of thing in production. The question: I'm looking for a way to do a neat hand-over of the TCP listening socket, from one process to another, and as a result get only a split second of downtime. I'd like existing connections / sockets to remain open and finish processing in the old process, while the new process starts servicing new connectinos. Is there some proven method of doing this using BSD-sockets? (Bonus points for an EventMachine solution.) Are there perhaps open-source libraries out there implementing this, that I can use as is, or use as a reference? (Again, non-Ruby and non-EventMachine solutions are appreciated too!)

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  • Can't get screen pixel from a specific full screen game with any language?

    - by user1007059
    Okay, I know this might seem like I'm posting a duplicate question since I've asked something similar like a day ago HOWEVER, if anyone sees any problem with this, please read my question first before judging: Yesterday I tried getting a specific pixel from a fullscreen game in C#. I thought my C# code was faulty but when I tried with multiple full screen games today they all worked except for that specific game. I literally tried with 10 different full screen games, a couple being mmofps, mmorpg, mmotps, regular rpg games, regular shooters, regular action adventure games, etc. I tried with multiple programming languages, and with every game except that specific game I'm dealing with, it returns the pixel color to me like I wanted. So let me explain what I tried: first I tried returning an IntPtr with C# using GetDC(IntPtr.Zero) before invoking GetPixel(int x, int y) and then getting the color out of it. Then I tried using the Robot class in Java and using the getPixelColor(int x, int y) method. I also tried using GetDC(0) to return an HDC object in C++ and then invoking GetPixel(int x, int y) before again extracting the color. These three methods worked EXACTLY the same in every single game except that specific game I was talking about. They returned the pixel perfectly, and extracted the exact same color perfectly. I don't feel it's necessary to tell you the game name or anything, since you probably don't even know it, but what could possibly be causing this malfunction in 1 specific game? PS: The game ALWAYS returns an RGB color of: A = 255, R = 0, G = 0, B = 0. Also, I tried taking a snapshot of the game with the 3 programming languages, and then getting the pixel which actually works in all 3 languages, but since I need to get this pixel every 30 ms, it kind of makes my game lag a bit (+ I think it takes up a lot of memory)

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  • What is the proper way to code a read-while loop in Scala?

    - by ARKBAN
    What is the "proper" of writing the standard read-while loop in Scala? By proper I mean written in a Scala-like way as opposed to a Java-like way. Here is the code I have in Java: MessageDigest md = MessageDigest.getInstance( "MD5" ); InputStream input = new FileInputStream( "file" ); byte[] buffer = new byte[1024]; int readLen; while( ( readLen = input.read( buffer ) ) != -1 ) md.update( buffer, 0, readLen ); return md.digest(); Here is the code I have in Scala: val md = MessageDigest.getInstance( hashInfo.algorithm ) val input = new FileInputStream( "file" ) val buffer = new Array[ Byte ]( 1024 ) var readLen = 0 while( readLen != -1 ) { readLen = input.read( buffer ) if( readLen != -1 ) md.update( buffer, 0, readLen ) } md.digest The Scala code is correct and works, but feels very un-Scala-ish. For one it is a literal translation of the Java code, taking advantage of none of the advantages of Scala. Further it is actually longer than the Java code! I really feel like I'm missing something, but I can't figure out what. I'm fairly new to Scala, and so I'm asking the question to avoid falling into the pitfall of writing Java-style code in Scala. I'm more interested in the Scala way to solve this kind of problem than in any specific helper method that might be provided by the Scala API to hash a file. (I apologize in advance for my ad hoc Scala adjectives throughout this question.)

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  • Concatenating a string and byte array in to unmanaged memory.

    - by Scott Chamberlain
    This is a followup to my last question. I now have a byte[] of values for my bitmap image. Eventually I will be passing a string to the print spooler of the format String.Format("GW{0},{1},{2},{3},", X, Y, stride, _Bitmap.Height) + my binary data; I am using the SendBytesToPrinter command from here. Here is my code so far to send it to the printer public static bool SendStringPlusByteBlockToPrinter(string szPrinterName, string szString, byte[] bytes) { IntPtr pBytes; Int32 dwCount; // How many characters are in the string? dwCount = szString.Length; // Assume that the printer is expecting ANSI text, and then convert // the string to ANSI text. pBytes = Marshal.StringToCoTaskMemAnsi(szString); pBytes = Marshal.ReAllocCoTaskMem(pBytes, szString.Length + bytes.Length); Marshal.Copy(bytes,0, SOMTHING GOES HERE,bytes.Length); // this is the problem line // Send the converted ANSI string + the concatenated bytes to the printer. SendBytesToPrinter(szPrinterName, pBytes, dwCount); Marshal.FreeCoTaskMem(pBytes); return true; } My issue is I do not know how to make my data appended on to the end of the string. Any help would be greatly appreciated, and if I am doing this totally wrong I am fine in going a entirely different way (for example somehow getting the binary data concatenated on to the string before the move to unmanaged space. P.S. As a second question, will ReAllocCoTaskMem move the data that is sitting in it before the call to the new location?

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  • m2eclipse: How to set Eclipse project settings when importing a maven project?

    - by Marius Andreiana
    Using m2eclipse Eclipse plugin, everybody on the dev team should be able to checkout source code, import Maven project in Eclipse and be good to go. I saw m2eclipse is being merged into Eclipse 3.7, and maven-eclipse-plugin won't be maintained any longer, so I'm looking for a m2eclipse-based solution (without running "mvn eclipse:clean eclipse:eclipse" before project import, which is what maven-eclipse-plugin does). maven-eclipse-plugin allows this in pom.xml <additionalConfig> <file> <name>.settings/com.google.gdt.eclipse.core.prefs</name> <content><![CDATA[ eclipse.preferences.version=2 jarsExcludedFromWebInfLib= warSrcDir=${project.build.directory}/${project.build.finalName} warSrcDirIsOutput=true ]]> </content> </file> The more general question is How would m2eclipse do something similar? For some cases, just saving the eclipse .settings/prefs file works (e.g. org.eclipse.jdt.ui.prefs), but in this case, com.google.gdt.eclipse.core.prefs is always overwritten on m2eclipse project import. A specific question is asked here, with no reply. Thanks! UPDATE: Not possible now, see request

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  • How to share the credentials between Webform and Winform?

    - by Daniel
    Hi! Question: I want to make a login form at the Clickonce deployment webpage, and only allow the authenticated users to download the application. and I want the downloaded application to use the same credentials entered at the webpage, without prompting the users to enter the credentials again. Details: I have an application(Windows Client) which needs customized settings for different users. the application is deployed through ClickOnce. Currently, the users are given the ClickOnce webpage URL, then download the application from there. after download and running the application, the application prompts users with a login form. If their credentials are authenticated, the application loads the customized settings from the server's database according to the credentials given. The problem is, any unauthenticated users can download the application if they just know the ClickOnce deployement webpage's URL. Unauthenticated users won't be able to run the application anyways, because the application asks for credentials when started, but I want to prevent the unauthenticated users from downloading the application at all. Am I asking the wrong question maybe? Your help is much appreciated!

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  • Recommend me an architecture for this Facebook application

    - by andybaird
    Firstly, this question is subjective. There is not a right answer for this question and it really depends on what works for you. I'm hoping to use this thread as a breeding ground for ideas. I hope this is acceptable in this medium. I'm working on building a Facebook app that will be replacing an already popular app that gets ~50k hits a day. The original app is using a very typical LAMP setup with help from some Zend libraries for database layer extraction. For the most part the app worked well, except to solve a lot of issues I ended up fragmenting tables to speed things up. As a result, I couldn't do a lot of things with the app that I wanted to (namely any processing using aggregate data that needed to be returned quickly) So I'm starting to design plans for the next version of this application, and I have a whole bunch of new and cool features that I know would choke my current setup. I'm looking for technological recommendations of data storage methods that scale well. The database does not necessarily need to be relational, simple key/value storage would suffice (although at present time I know little to nothing about KV stores) What's your recommendation? How would you tackle this? I'd like to take a completely free approach to this -- although I am most familiar and comfortable using PHP, I want to leave all technical options open.

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  • How To Create a Flexible Plug-In Architecture?

    - by justkt
    A repeating theme in my development work has been the use of or creation of an in-house plug-in architecture. I've seen it approached many ways - configuration files (XML, .conf, and so on), inheritance frameworks, database information, libraries, and others. In my experience: A database isn't a great place to store your configuration information, especially co-mingled with data Attempting this with an inheritance hierarchy requires knowledge about the plug-ins to be coded in, meaning the plug-in architecture isn't all that dynamic Configuration files work well for providing simple information, but can't handle more complex behaviors Libraries seem to work well, but the one-way dependencies have to be carefully created. As I seek to learn from the various architectures I've worked with, I'm also looking to the community for suggestions. How have you implemented a solid plug-in architecture? What was your worst failure (or the worst failure you've seen)? What would you do if you were going to implement a new plug-in architecture? What SDK or open source project that you've worked with has the best example of a good architecture? A few examples I've been finding on my own: Perl's Module::Plugable An SO question with a list for Java (including Sever Provider Interfaces) An SO question for C++ pointing to a Dr. Dobbs article These examples seem to play to various language strengths. Is a good plugin architecture necessarily tied to the language? Is it best to use tools to create a plugin architecture, or to do it on one's own following models?

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  • google chrome extension update text after response callback

    - by Jerome
    I am writing a Google Chrome extension. I have reached the stage where I can pass messages back and forth readily but I am running into trouble with using the response callback. My background page opens a message page and then the message page requests more information from background. When the message page receives the response I want to replace some of the standard text on the message page with custom text based on the response. Here is the code: chrome.extension.sendRequest({cmd: "sendKeyWords"}, function(response) { keyWordList=response.keyWordsFound; var keyWords=""; for (var i = 0; i FIRST QUESTION: This all seems to work fine but the text on the page doesn't change. I am almost certainly because the callback completes after the page is finished loading and the rest of the code finishes before the callback completes, too. How do I update the page with the new text? Can I listen for the callback to complete or something like that? SECOND QUESTION: The procedure I am pursuing first opens the message page and then the message page requests the keyword list from background. Since I always want the keyword list, it makes more sense to just send it when I create the tab. Can I do that? Here is the code from background that opens the message page: //when request from detail page to open message page chrome.extension.onRequest.addListener(function(request, sender, sendResponse) { if(request.cmd == "openMessage") { console.log("Received Request to Open Message, Profile Score: "+request.keyWordsFound.length); keyWordList=request.keyWordsFound; chrome.tabs.create({url: request.url}, function(tab){ msgTabId=tab.id; //needed to determine if message tab has later been closed chrome.tabs.executeScript(tab.id, {file: "message.js"}); }); console.log("Opening Message"); } });

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  • AI navigation around a 2d map - Avoiding obstacles.

    - by Curt Walker
    Hey there, I know my question seems pretty vague but I can't think of a better way to put it so I'll start off by explaining what I'm trying to do. I'm currently working on a project whereby I've been given a map and I'm coding a 'Critter' that should be able to navigate it's way around the map, the critter has various other functions but are not relevant to the current question. The whole program and solution is being written in C#. I can control the speed of the critter, and retrieve it's current location on the map by returning it's current X and Y position, I can also set it's direction when it collides with the terrain that blocks it. The only problem I have is that I can't think of a way to intelligently navigate my way around the map, so far I've been basing it around what direction the critter is facing when it collides with the terrain, and this is in no way a good way of moving around the map! I'm not a games programmer, and this is for a software assignment, so I have no clue on AI techniques. All I am after is a push in the right direction on how I could go about getting this critter to find it's way around any map given to me. Here's an image of the map and critters to give you an idea of what i'm talking about. Here's a link to an image of what the maps and critters look like. Map and Critter image I'm in no way looking for anyone to give me a full solution, just a push in the general direction on map navigation. Thanks in advance!

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  • using a 64-bit compiler in microsoft visual c++

    - by Ben
    this question is essentially identical to an earlier question i had that didn't receive any answers. hopefully someone can help me out this time. i am trying to compile a vc++ project as 64 bit using visual c++ express 2010. i know that the 64 bit compiler does not come with the default installation of vc++ express so i installed windows sdk for windows 7 as specified here (http://msdn.microsoft.com/en-us/library/9yb4317s.aspx) which includes the 64 bit compiler as i understand. however, there is still no 64 bit option in the configuration manager for vc++. after some searching i found and completed this tutorial (http://jenshuebel.wordpress.com/2009/02/12/visual-c-2008-express-edition-and-64-bit-targets/) as well as the various links at the bottom of this page. despite all my efforts, i still cannot get the 64 bit compiler to show in vc++ (i.e. the 64 bit compiler won't show under "active solutions platform" in the configuration manager). if anyone has any experience/tips with getting this to work i would really appreciate it. fyi - i am running windows 7(x64).

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  • release object of a return method object c

    - by Piero
    in run the app with the analyze build, and Xcode found me a lot of memory leak and there is one in particular that i don't know how solve here it is: - (UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section { UIImageView *sectionImage = [[UIImageView alloc] init]; if (section == 0)sectionImage.image = [UIImage imageNamed:@"myImage.png"]; return sectionImage; } so my question is, how i can release this sectionImage? if is the return of the method? EDIT: i have another question, analyze give me another memory leak, i have this: .h @property (nonatomic, retain) NSIndexPath *directCellPath; .m @synthesize directCellPath = _directCellPath; - (id)init{ if ((self = [super initWithNibName:@"MyViewController" bundle:nil])) { self.directCellPath = [[NSIndexPath alloc] init]; } return self; } then in the code i use it and finally in the dealloc i do this: - (void)dealloc { [_directCellPath release]; [super dealloc]; } and give me a memory leak on this line: self.directCellPath = [[NSIndexPath alloc] init]; why if i have deallocated it in the dealloc?

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  • SQLite dataypes lengths?

    - by XF
    I'm completely new to SQLite (actually 5 minutes ago), but I do know somewhat the Oracle and MySql backends. The question: I'm trying to know the lengths of each of the datatypes supported by SQLite, such as the differences between a bigint and a smallint. I've searched across the SQLite documentation (only talks about affinity, only matters it?), SO threads, google... and found nothing. My guess: I've just slightly revised the SQL92 specifications, which talk about datatypes and its relations but not about its lengths, which is quite obvious I assume. Yet I've come accross the Oracle and MySql datatypes specs, and the specified lengths are mostly identical for integers at least. Should I assume SQLite is using the same lengths? Aside question: Have I missed something about the SQLite docs? Or have I missed something about SQL in general? Asking this because I can't really understand why the SQLite docs don't specify something as basic as the datatypes lengths. It just doesn't make sense to me! Although I'm sure there is a simple command to discover the lengths.. but why not writing them to the docs? Thank you!

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  • Entity Framework in layered architecture

    - by Kamyar
    I am using a layered architecture with the Entity Framework. Here's What I came up with till now (All the projects Except UI are class library): Entities: The POCO Entities. Completely persistence ignorant. No Reference to other projects. Generated by Microsoft's ADO.Net POCO Entity Generator. DAL: The EDMX (Entity Model) file with the context class. (t4 generated). References: Entities BLL: Business Logic Layer. Will implement repository pattern on this layer. References: Entities, DAL. This is where the objectcontext gets populated: var ctx=new DAL.MyDBEntities(); UI: The presentation layer: ASP.NET website. References: Entities, BLL + a connection string entry to entities in the config file (question #2). Now my three questions: Is my layer discintion approach correct? In my UI, I access BLL as follows: var customerRep = new BLL.CustomerRepository(); var Customer = customerRep.GetByID(myCustomerID); The problem is that I have to define the entities connection string in my UI's web.config/app.config otherwise I get a runtime exception. IS defining the entities connectionstring in UI spoils the layers' distinction? Or is it accesptible in a muli layered architecture. Should I take any additional steps to perform chage tracking, lazy loading, etc (by etc I mean the features that Entity Framework covers in a conventional, 1 project, non POCO code generation)? Thanks and apologies for the lengthy question.

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  • PHP: Profiling code and strict environment ~ Improving my coding

    - by DavidYell
    I would like to update my local working environment to be stricter in an effort to improve my code. I know that my code is okay, but as with most things there is always room for improvement. I use XAMPP on my local machine, for simplicities sake Apache Friends XAMPP (Basic Package) version 1.7.2 So I've updated my php.ini : error_reporting to be E_ALL | E_STRICT to help with the code standard. I've also enabled the XDebug extension zend_extension = "C:\xampp\php\ext\php_xdebug.dll" which seems to be working, having tested some broken code and got the nice standard orange error notice. However, having read this question, http://stackoverflow.com/questions/133686/what-is-the-best-way-to-profile-php-code and enabled the profiler, I cannot seem to create a cachegrind file. Many of the guides that I've looked at seem to think you need to install XDebug in XAMPP which leads me to think they are out of date, as XDebug is bundled with XAMPP these days. So I would appreciate it if anyone can help point me in the right direction with both configuring XDebug to output grind files, and or just a great set of default settings for the XDebug config in XAMPP. Seems there is very little documentation to go on. If people have tips on integrating these tools with Netbeans, that would be awesomesauce. I'm happy to get suggestions on other things that I can do to help tighten up my php code, both syntactically and performance wise Thanks, and apologies for the rambling question(s)! Ninja edit I should menion that I'm using named vhosts as my Apache configuration, which I think is why running XDebug on port 9000 isn't working for me. I guess I'd need to edit my vhost to include port 9000

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  • Audio output from Silverlight

    - by leecarter
    I'm looking to develop a Silverlight application which will take a stream of data (not an audio stream as such) from a web server. The data stream would then be manipulated to give audio of a certain format (G.711 a-Law for example) which would then be converted into PCM so that additional effects can be applied (such as boosting the volume). I'm OK up to this point. I've got my data, converted the G.711 into PCM but my problem is being able to output this PCM audio to the sound card. I basing a solution on some C# code intended for a .Net application but in Silverlight there is a problem with trying to take a copy of a delegate (function pointer) which will be the topic of a separate question once I've produced a simple code sample. So, the question is... How can I output the PCM audio that I have held in a data structure (currently an array) in my Silverlight to the user? (Please don't say write the byte values to a text box) If it were a MP3 or WMA file I would play it using a MediaElement but I don't want to have to make it into a file as this would put a crimp on applying dynamic effects to the audio. I've seen a few posts from people saying low level audio support is poor/non-existant in Silverlight so I'm open to any suggestions/ideas people may have.

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  • R plotting multiple histograms on single plot to .pdf as a part of R batch script

    - by Bryce Thomas
    I am writing R scripts which play just a small role in a chain of commands I am executing from a terminal. Basically, I do much of my data manipulation in a Python script and then pipe the output to my R script for plotting. So, from the terminal I execute commands which look something like $python whatever.py | R CMD BATCH do_some_plotting.R. This workflow has been working well for me so far, though I have now reached a point where I want to overlay multiple histograms on the same plot, inspired by this answer to another user's question on Stackoverflow. Inside my R script, my plotting code looks like this: pdf("my_output.pdf") plot(hist(d$original,breaks="FD",prob=TRUE), col=rgb(0,0,1,1/4),xlim=c(0,4000),main="original - This plot is in beta") plot(hist(d$minus_thirty_minutes,breaks="FD",prob=TRUE), col=rgb(1,0,0,1/4),add=T,xlim=c(0,4000),main="minus_thirty_minutes - This plot is in beta") Notably, I am using add=T, which is presumably meant to specify that the second plot should be overlaid on top of the first. When my script has finished, the result I am getting is not two histograms overlaid on top of each other, but rather a 3-page PDF whose 3 individual plots contain the titles: i) Histogram of d$original ii) original - This plot is in beta iii) Histogram of d$minus_thirty_minutes So there's two points here I'm looking to clarify. Firstly, even if the plots weren't overlaid, I would expect just a 2-page PDF, not a 3-page PDF. Can someone explain why I am getting a 3-page PDF? Secondly, is there a correction I can make here somewhere to get just the two histograms plotted, and both of them on the same plot (i.e. 1-page PDF)? The other Stackoverflow question/answer I linked to in the first paragraph did mention that alpha-blending isn't supported on all devices, and so I'm curious whether this has anything to do with it. Either way, it would be good to know if there is a R-based solution to my problem or whether I'm going to have to pipe my data into a different language/plotting engine.

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  • Database table relationships: Always also relate to specified value (Linq to SQL in .NET Framework)

    - by sinni800
    I really can not describe my question better in the title. If anyone has suggestions: Please tell! I use the Linq to SQL framework in .NET. I ran into something which could be easily solved if the framework supported this, it would be a lot of extra coding otherwise: I have a n to n relation with a helper table in between. Those tables are: Items, places and the connection table which relates items to places and the other way. One item can be found in many places, so can one place have many items. Now of course there will be many items which will be in ALL places. Now there is a problem: Places can always be added. So I need a place-ID which encompasses ALL places, always. Like maybe a place-id "0". If the helper table has a row with the place-id of zero, this should be visible in all places. In SQL this would be a simple "Where [...] or place-id = 0", but how do I do this in Linq relations? Also, for a little side question: How could I manage "all but this place" kind of exclusions?

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  • Is there a standard pattern for scanning a job table executing some actions?

    - by Howiecamp
    (I realize that my title is poor. If after reading the question you have an improvement in mind, please either edit it or tell me and I'll change it.) I have the relatively common scenario of a job table which has 1 row for some thing that needs to be done. For example, it could be a list of emails to be sent. The table looks something like this: ID Completed TimeCompleted anything else... ---- --------- ------------- ---------------- 1 No blabla 2 No blabla 3 Yes 01:04:22 ... I'm looking either for a standard practice/pattern (or code - C#/SQL Server preferred) for periodically "scanning" (I use the term "scanning" very loosely) this table, finding the not-completed items, doing the action and then marking them completed once done successfully. In addition to the basic process for accomplishing the above, I'm considering the following requirements: I'd like some means of "scaling linearly", e.g. running multiple "worker processes" simultaneously or threading or whatever. (Just a specific technical thought - I'm assuming that as a result of this requirement, I need some method of marking an item as "in progress" to avoid attempting the action multiple times.) Each item in the table should only be executed once. Some other thoughts: I'm not particularly concerned with the implementation being done in the database (e.g. in T-SQL or PL/SQL code) vs. some external program code (e.g. a standalone executable or some action triggered by a web page) which is executed against the database Whether the "doing the action" part is done synchronously or asynchronously is not something I'm considering as part of this question.

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  • Java try finally variations

    - by Petr Gladkikh
    This question nags me for a while but I did not found complete answer to it yet (e.g. this one is for C# http://stackoverflow.com/questions/463029/initializing-disposable-resources-outside-or-inside-try-finally). Consider two following Java code fragments: Closeable in = new FileInputStream("data.txt"); try { doSomething(in); } finally { in.close(); } and second variation Closeable in = null; try { in = new FileInputStream("data.txt"); doSomething(in); } finally { if (null != in) in.close(); } The part that worries me is that the thread might be somewhat interrupted between the moment resource is acquired (e.g. file is opened) but resulting value is not assigned to respective local variable. Is there any other scenarios the thread might be interrupted in the point above other than: InterruptedException (e.g. via Thread#interrupt()) or OutOfMemoryError exception is thrown JVM exits (e.g. via kill, System.exit()) Hardware fail (or bug in JVM for complete list :) I have read that second approach is somewhat more "idiomatic" but IMO in the scenario above there's no difference and in all other scenarios they are equal. So the question: What are the differences between the two? Which should I prefer if I do concerned about freeing resources (especially in heavily multi-threading applications)? Why? I would appreciate if anyone points me to parts of Java/JVM specs that support the answers.

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  • Opengl: fit a quad to screen, given the value of Z.

    - by hytparadisee
    Short Version of the question: I will put a quad. I know the width and height of the screen in window coordinates, i know the Z-coordinates of the quad in 3D. I know the FOVY, I know the aspect. The quad will be put along Z-axis, My camera doesn't move (placed at 0, 0, 0). I want to find out the width and height of the quad IN 3D COORDINATES that will fit exactly onto my screen. Long Version of the question: I would like to put a quad along the Z-axis at the specified offset Z, I would like to find out the width and height of the quad that will exactly fill the entire screen. I used to have a post on gamedev.net that uses a formula similar to the following: *dist = Z * tan ( FOV / 2 )* Now I can never find the post! Though it's similar, it is still different, because I remembered in that working formula, they do make use of screenWidth and screenHeight, which are the width and height of the screen in window coordinates. I am not really familiar with concepts like frustum, fov and aspect so that's why I can't work out the formula on my own. Besides, I am sure I don't need gluUnproject (I tried it, but the results are way off). It's not some gl calls, it's just a math formula that can find out the width and height in 3D space that can fill the entire screen, IF Z offset, width in window coordinates, and height in window coordinates, are known. Thanks all in advance.

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