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  • OpenCV and iPhone

    - by gn-mithun
    Hello, I am writing an application to create a movie file from a bunch of images on an iPhone. I am using OpenCv. I downloaded openCv static libraries for arm(iPhones native instruction architecture) and the libraries were generated just fine. There were no problems linking to them libraries. As a first step, i was trying to create a .avi file using one image, to see if it works. But cvCreateVideoWriter always returns me a NULL value. I did some searchin and i believe its due to the codec not being present. I am trying this on the iPhone simulator. this is what i do... (void)viewDidLoad { [super viewDidLoad]; UIImage *anImage = [UIImage imageNamed:@"1.jpg"]; IplImage *img_color = [self CreateIplImageFromUIImage:anImage]; //The image gets created just fine CvVideoWriter *writer = cvCreateVideoWriter("out.avi",CV_FOURCC('P','I','M','1'), 25,cvSize(320,480),1); //writer is always null int result = cvWriteFrame(writer, img_color); NSLog(@"\n%d",result); //hence this is also 0 all the time cvReleaseVideoWriter(&writer); } I am not sure about the the second parameter. What sort of codec or what exactly it does... I am a n00B in this. Any suggestions?

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  • Biztalk vs API for databroker layer

    - by jdt199
    My company is about to undergo a large project in which our client wants a large customer portal with a cms, crm implementing. This will require interaction with data from multiple sources across our customers business, these sources include XML office backend systems, sql datbases, webservices etc. Our proposed solution would be to write an API in c# to provide a common interface with all these systems. This would be scalable for future and concurrent projects within the company. Our client expressed an interest in using Biztalk rather than a custom API for this integration, as they feel it is an enterprise solution that any of their suppliers could pick up and use, and it will be better supported. We feel that the configuration work using Biztalk would be rather heavy for all their custom business rules which are required and an interface for the new application to get data to and from Biztalk would still need to be written. Are we right to prefer a custom API solution above Biztalk? Would Biztalk be suitable as a databroker layer to provide an interface for the new Customer portal we are writing. We have not experience with using Biztalk before so any input would be appreciated.

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  • Making a jQuery plugin to feed Tumblr to site

    - by tylorreimer
    I have some experience with PHP and a little with JS but I'm far from anything proficient. I'm trying to make a jQuery plugin for my site that I can call in my HTML via something like this: $('.new').tumble({username: "tylor", count: 9}); Which would basically put the Tumblr list the code should make into the DIV with class 'new' in this case. Here is my code so far; the problem seems to be how to get it to pick up class/id from the original call (in the HTML) and use that in the jQuery. Here's the code so far: (function($) { $.fn.tumble = function(options){ var settings = $.extend({ username: null, // [string or array] required to get url for tumblr account count: 3, // [integer] how many posts to display? }, options); //url construction var url = "http://" + settings.username + ".tumblr.com"; var jsonurl = url + "/api/read/json?num=" + settings.count + "&callback=?"; $.getJSON(jsonurl, function(data) { var items = []; $.each(data.posts, function(id, url) { // Goes over each post in the JSON document retrieved from data URL var url = this.url; // Just assigns a variable to the url to avoid constantly writing "this.whatever" var photourl = this['photo-url-250']; // photo-url-xxx needs to be called this way due to integers in the name items.push('<li><a href="' + url + '">' + photourl + '</a></li>'); }); $('<ul/>', { // Creates an empty list html: items.join('') // Takes the values in the item array and puts 'em together }).appendTo('.new'); // I don't want this to have the class set in the jQuery itself }); //end json }; })( jQuery ); Any help you can lend would be wonderful. Thank you

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  • is it possible to write a method which creates a method?

    - by Alan Bennett
    hey guys, this might seem like a no brainer but hopefully after i explain my problem you might understand why i am asking this. is it possible to have a method which creates a method and its arguements? the problem: in my current project i have to many times call different sql statements which arent all that different. for example i have one where i inserts some new rows but only has 2 columns and another which also inserts new rows but has 12 columns. i have created a class called utils.cs and in there i have sorted many "handy" methods, such as validation methods which check for numeric input to text boxes etc. so i thought well instead of having sql writing methods everywhere ill make one in there and call it when i need to so i have but it currently looks like this: public static string getInsertSQL(string tablename, string colOne, string colTwo, string colThree, string colFour, string colFive, string colSix, string colSeven, string colEight, string colNine, string colTen, string colEleven, string colTwelve,bool active, string valueOne, string valueTwo, string valueThree, string valueFour, string valueFive, string valueSix, string valueSeven, string valueEight, string valueNine, string valueTen, string valueEleven) { string strSQL = ""; strSQL += "INSERT INTO " + tablename; strSQL += "(" + colOne + " " + colTwo + " " + colThree + " " + colFour + " " + colFive + " " + colSix + " " + colSeven + " " + colEight + " " + colNine + " " + colTen + " " + colEleven + " " + colTwelve + " )"; strSQL += " values ("+active+", " + valueOne + " " + valueTwo + " " + valueThree + " " + valueFour + " " + valueFive + " " + valueSix + " " + valueSeven + " " + valueEight + " " + valueNine + " " + valueTen + " " + valueEleven + " )"; return strSQL; } as you can see thats quite a mess so i wondered if it was at all possible to write a method which would take an arguement of how many colums needed to be inserted and then could create a method with that many arguements. i hope you can see what i am getting at and dont just sound like a plep! thanks in advance

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  • Setting directory security to allow user and deny all

    - by Rita
    I have winforms app, in which I need to access a secured directory. I'm using impersonation and create WindowsIdentity to access the folder. My problem is writing unit tests to test the directory security; I'd like to a write a code that creates a directory secured to only ONE user, which isn't the current user running the UT (or else the test would be worthless). I know how to add permissions to a certain user, but how can I deny the rest, including admins? (in case the user running the UT is an admin) (will this be a wise thing to do?) DirectoryInfo directoryInfo = new DirectoryInfo(path); DirectorySecurity directorySecurity = directoryInfo.GetAccessControl(); directorySecurity.AddAccessRule(new FileSystemAccessRule("Domain\SecuredUser", FileSystemRights.FullControl, InheritanceFlags.ContainerInherit | InheritanceFlags.ObjectInherit, PropagationFlags.InheritOnly, AccessControlType.Allow)); directorySecurity.RemoveAccessRule(new FileSystemAccessRule("??", FileSystemRights.FullControl, InheritanceFlags.ContainerInherit | InheritanceFlags.ObjectInherit, PropagationFlags.InheritOnly, AccessControlType.Deny)); directoryInfo.SetAccessControl(directorySecurity); This isn't working. I don't know who am I supposed to deny. Domain\Admins, Domain\Administrators, me... No one is being denied, and when I check folder's security - The SecuredUser has access to the folder, but the permissions are not checked, even though I specified FullControl. Basically I want to code this: <authorization> <allow users ="Domain\User" /> <deny users="*" /> </authorization> I was thinking about impersonating UT run with a weak user with no permissions, but this would result in: Impersonate - Run UT - Impersonate - Access folder, and I'm not sure if this is the right design. Help would be greatly appreciated, thank you.

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  • How to get the actual address of a pointer in C?

    - by Airjoe
    BACKGROUND: I'm writing a single level cache simulator in C for a homework assignment, and I've been given code that I must work from. In our discussions of the cache, we were told that the way a small cache can hold large addresses is by splitting the large address into the position in the cache and an identifying tag. That is, if you had an 8 slot cache but wanted to store something with address larger than 8, you take the 3 (because 2^3=8) rightmost bits and put the data in that position; so if you had address 22 for example, binary 10110, you would take those 3 rightmost bits 110, which is decimal 5, and put it in slot 5 of the cache. You would also store in this position the tag, which is the remaining bits 10. One function, cache_load, takes a single argument, and integer pointer. So effectively, I'm being given this int* addr which is an actual address and points to some value. In order to store this value in the cache, I need to split the addr. However, the compiler doesn't like when I try to work with the pointer directly. So, for example, I try to get the position by doing: npos=addr%num_slots The compiler gets angry and gives me errors. I tried casting to an int, but this actually got me the value that the pointer was pointing to, not the numerical address itself. Any help is appreciated, thanks!

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  • Detecting Connection Speed / Bandwidth in .net/WCF

    - by Mystagogue
    I'm writing both client and server code using WCF, where I need to know the "perceived" bandwidth of traffic between the client and server. I could use ping statistics to gather this information separately, but I wonder if there is a way to configure the channel stack in WCF so that the same statistics can be gathered simultaneously while performing my web service invocations. This would be particularly useful in cases where ICMP is disabled (e.g. ping won't work). In short, while making my regular business-related web service calls (REST calls to be precise), is there a way to collect connection speed data implicitly? Certainly I could time the web service round trip, compared to the size of data used in the round-trip, to give me an idea of throughput - but I won't know how much of that perceived bandwidth was network related, or simply due to server-processing latency. I could perhaps solve that by having the server send back a time delta, representing server latency, so that the client can compute the actual network traffic time. If a more sophisticated approach is not available, that might be my answer...

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  • Subsonic in a VS2008 Add-In woes

    - by Michael Smit
    Hi, I am writing a VS2008 add-in that connects to a remote database blah blah. I am having a problem with the app.config in this project. When I use SubSonic in my code, it moans that is cannot find the SubSonicServer section. This is because the .config file cannot be found. This appears to a problem with paths as the add-in is a DLL running in the context of VS2008 and the working directory is C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE. Is there a way to get the app.config to deploy properly with the application so my add-in (and SubSonic) can find what it needs in the .config file, or is there a way to get SubSonic to work without the need for the .config? I am very experienced in SubSonic projects now, but only winforms, web, web service, and WPF applications. This is the first time I have tried to use SubSonic in a VS2008 Add-In project. I also have AppSettings in the config file which the ConfigurationManager cannot read because it cannot see the .config file. 2AM now and brain is tired of trying to figure this one out. Hopefully there is an answer when I wake up :) TIA

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  • ClassLoader exceptions being memoized

    - by Jim
    Hello, I am writing a classloader for a long-running server instance. If a user has not yet uploaded a class definition, I through a ClassNotFoundException; seems reasonable. The problem is this: There are three classes (C1, C2, and C3). C1 depends on C2, C2 depends on C3. C1 and C2 are resolvable, C3 isn't (yet). C1 is loaded. C1 subsequently performs an action that requires C2, so C2 is loaded. C2 subsequently performs an action that requires C3, so the classloader attempts to load C3, but can't resolve it, and an exception is thrown. Now C3 is added to the classpath, and the process is restarted (starting from the originally-loaded C1). The issue is, C2 seems to remember that C3 couldn't be loaded, and doesn't bother asking the classloader to find the class... it just re-throws the memoized exception. Clearly I can't reload C1 or C2 because other classes may have linked to them (as C1 has already linked to C2). I tried throwing different types of errors, hoping the class might not memoize them. Unfortunately, no such luck. Is there a way to prevent the loaded class from binding to the exception? That is, I want the classloader to be allowed to keep trying if it didn't succeed the first time. Thanks!

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  • tips for fixing bad coding/dev habits ?

    - by dfafa
    i want to become a better coder....so i have decided to sign up for computing science program...maybe a formal education can assist me. i started working on smaller projects to learn but currently i have really bad coding/dev habits which is hindering my productivity as the codebase increases.... i have highlighted them and perhaps someone could make suggestions (or redirect to resources) or a more efficient method. most stuff that i made in the past were web apps. i usually develop with putty + nano...i just love the minimalist feel i use winscp and develop directly on my private web server...too lazy to do it on localhost and upload it later. i dont use subversion control...which one do i need ? sometimes ctrl +z doesn't work well. when i run out of ideas for naming variable, i use swear words instead. i swear a lot when i get stuck....how to deal with anger issue ? my codes look ugly with comments everywhere. would rather use procedural coding finds "thinking" in OO difficult and time consuming i "write first think later". refactors code only if i am getting paid for it. dislikes configuring linux distro, Apache, MySQL, scaling, designing graphics and layouts. does not like writing tests likes working alone. does not like sharing codes. has an econ degree dislikes reading other people's code would rather write it on my own it seems my only true desire is to translate my ideas to a working prototype as fast as possible....it seems like i am very uninterested in the other details...could it be that i am not cut out to be a coder after all ? is going back to study comp sci a bad idea ?

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  • Scrolling to the bottom of a div on page load: issue with syntaxhighlighter

    - by Rayne
    I've been using this code: var objDiv = document.getElementById("code"); objDiv.scrollTop = objDiv.scrollHeight; to scroll to the very bottom of the div. It worked perfectly in FF and Chrome (I asked a question about it not working in Chrome a few days ago, but it appears the guy who was testing it on Chrome was incorrect, so I tested it myself) until I started syntax highlighting the code that I put in the div with SyntaxHighlighter. Before, I was putting the code in a <p> and breaking lines with <br />, but the <br /> stuff doesn't fly with SyntaxHighlighter, so I replaced all of those with newlines (not entirely certain if this is important, but it's worth mentioning). Now, when the page loads, it does scroll, but not all the way down. It scrolls nearly to the bottom. I've tried all the methods listed in the other question I mentioned but they all do the same thing, or nothing at all. Is there anything else I can try? Here is the relevant piece of the generated HTML. Forgive the poor formatting, I'm not writing the HTML by hand, but rather using Hiccup with Clojure, and it doesn't bother with formatting. <div class="scroll" id="code"><pre class="brush: clojure">=> (doseq [x (range 1 100)] (println x)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 nil </pre></div><script type="text/javascript">var objDiv = document.getElementById("code"); objDiv.scrollTop = objDiv.scrollHeight;</script>

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  • Can PHP dissect its own syntax?

    - by Nathan Long
    Can PHP dissect its own syntax? For example, I'd like to write a function that takes in an input like $object->attribute and says to itself: OK, he's giving me $foo->bar, which means he must think that $foo is an object that has a property called bar. Before I try accessing bar and potentially get a 'Trying to get property of non-object' error, let me check whether $foo is even an object. The end goal is to echo a value if it is set, and fail silently if not. I want to avoid repetition like this: <input value="<? if(is_object($foo) && is_set($foo->bar)){ echo $foo->bar; }?> "/> ...and to avoid writing a function that does the above, but has to have the object and attribute passed in separately, like this: <input value="<? echoAttribute($foo,'bar') ?>" /> ...but to instead write something which: preserves the object-attribute syntax is flexible: can also handle array keys or regular variables Like this: <input value="<? echoIfSet($foo->bar); ?> /> <input value="<? echoIfSet($baz['buzz']); ?> /> <input value="<? echoIfSet($moo); ?> /> But this all depends on PHP being able to tell me "what kind of thing am I asking for when I say $object->attribute or $array[$key]", so that my function can handle each according to its own type. Is this possible?

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  • requesting ajax via HttpWebRequest

    - by Sami Abdelgadir Mohammed
    Hi guys: I'm writing a simple application that will download some piece of data from a website then I can use it later for any purpose The following is the request and response copied from Firebug as the browser did that... when u type http://x5.travian.com.sa/ajax.php?f=k7&x=18&y=-186&xx=12&yy=-192 you will get a php file has some data.. But when I make a request with HttpWebRequest I get wrong data (some unknown letters) Can anyone help me in that.. and if I have to make some encodings or what?? I will be so appreciated.. Response Server nginx Date Tue, 04 Jan 2011 23:03:49 GMT Content-Type application/json; charset=UTF-8 Transfer-Encoding chunked Connection keep-alive X-Powered-By PHP/5.2.8 Expires Mon, 26 Jul 1997 05:00:00 GMT Last-Modified Tue, 04 Jan 2011 23:03:49 GMT Cache-Control no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Pragma no-cache Content-Encoding gzip Vary Accept-Encoding Request Host x5.travian.com.sa User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13 Accept text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 115 Connection keep-alive Cookie CAD=57878984%231292375897%230%230%23%230; T3E=%3DImYykTN2EzMmhjO5QTM2QDN2oDM1ITOyoDOxIjM4EDN5ITM6gjO4MDOxIWZyQWMipTZu9metl2ctl2c6MDNxADN6MDNxADNjMDNxADNjMDNxADN; orderby_b1=0; orderby_b=0; orderby2=0; orderby=0

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  • Return a list of important Python modules in a script?

    - by Jono Bacon
    Hi All, I am writing a program that categorizes a list of Python files by which modules they import. As such I need to scan the collection of .py files ad return a list of which modules they import. As an example, if one of the files I import has the following lines: import os import sys, gtk I would like it to return: ["os", "sys", "gtk"] I played with modulefinder and wrote: from modulefinder import ModuleFinder finder = ModuleFinder() finder.run_script('testscript.py') print 'Loaded modules:' for name, mod in finder.modules.iteritems(): print '%s ' % name, but this returns more than just the modules used in the script. As an example in a script which merely has: import os print os.getenv('USERNAME') The modules returned from the ModuleFinder script return: tokenize heapq __future__ copy_reg sre_compile _collections cStringIO _sre functools random cPickle __builtin__ subprocess cmd gc __main__ operator array select _heapq _threading_local abc _bisect posixpath _random os2emxpath tempfile errno pprint binascii token sre_constants re _abcoll collections ntpath threading opcode _struct _warnings math shlex fcntl genericpath stat string warnings UserDict inspect repr struct sys pwd imp getopt readline copy bdb types strop _functools keyword thread StringIO bisect pickle signal traceback difflib marshal linecache itertools dummy_thread posix doctest unittest time sre_parse os pdb dis ...whereas I just want it to return 'os', as that was the module used in the script. Can anyone help me achieve this?

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  • Turning off antialiasing in Löve2D

    - by cjanssen
    I'm using Löve2D for writing a small game. Löve2D is an open source game engine for Lua. The problem I'm encountering is that some antialias filter is automatically applied to your sprites when you draw it at non-integer positions. love.graphics.draw( sprite, x, y ) So when x or y is not round (for example, x=100.24), the sprite appears blurred. The same happens when the sprite size is not even, because (x,y) points to the center of the sprite. For example, a sprite which is 31x30 big will appear blurred again, because its pixels are painted in non-integer positions. Since I am using pixel art, I want to avoid this all the way, otherwise the art is destroyed by this effect. The workaround I am using so far is to force the coordinates to be round by littering the code with calls to math.floor(), and forcing all the sprites to have even sizes by adding a row or column of transparent pixels with the paint program, if needed. Is there some command to deactivate the antialiasing I can call at program startup?

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  • How can "today's date" be varied for unit testing purposes?

    - by ck
    I use VS2008 targetting .NET 2.0 Framework, and, just in case, no I can't change this :) I have a DateCalculator class. Its method GetNextExpirationDate attempts to determine the next expiration, internally using DateTime.Today as a baseline date. As I was writing unit tests, I realized that I wanted to test GetNextExpirationDate for different 'today' dates. What's the best way to do this? Here are some alternatives I've considered: Expose a property/overloaded method with argument baselineDate and only use it from the unit test. In actual client code, disregard the property/overloaded method in favour of the method that defaults baselineDate to DateTime.Today. I'm reluctant to do this as it makes the public interface of the DateCalculator class awkward. Create a protected field called baselineDate that is internally set to DateTime.Today. When testing, derive a DateCalculatorForTesting from DateCalculator and set baslineDate via the constructor. It keeps the public interface clean, but still isn't great - baselineDate was made protected and a derived class is required, both solely for testing. Use extension methods. I tried this after adding the ExtensionAttribute, then realized it wouldn't work because extension methods can't access private/protected variables. I initially thought this was really quite an elegant solution. :( I'd be interested in hearing what others think.

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  • int considered harmful?

    - by Chris Becke
    Working on code meant to be portable between Win32 and Win64 and Cocoa, I am really struggling to get to grips with what the @#$% the various standards committees involved over the past decades were thinking when they first came up with, and then perpetuated, the crime against humanity that is the C native typeset - char, short, int and long. On the one hand, as a old-school c++ programmer, there are few statements that were as elegant and/or as simple as for(int i=0; i<some_max; i++) but now, it seems that, in the general case, this code can never be correct. Oh sure, given a particular version of MSVC or GCC, with specific targets, the size of 'int' can be safely assumed. But, in the case of writing very generic c/c++ code that might one day be used on 16 bit hardware, or 128, or just be exposed to a particularly weirdly setup 32/64 bit compiler, how does use int in c++ code in a way that the resulting program would have predictable behavior in any and all possible c++ compilers that implemented c++ according to spec. To resolve these unpredictabilities, C99 and C++98 introduced size_t, uintptr_t, ptrdiff_t, int8_t, int16_t, int32_t, int16_t and so on. Which leaves me thinking that a raw int, anywhere in pure c++ code, should really be considered harmful, as there is some (completely c++xx conforming) compiler, thats going to produce an unexpected or incorrect result with it. (and probably be a attack vector as well)

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  • special debugging lines (java)

    - by David
    Recently i've found myself writing a lot of methods with what i can only think to call debugging scaffolding. Here's an example: public static void printArray (String[] array, boolean bug) { for (int i = 0; i<array.lenght; i++) { if (bug) System.out.print (i) ; //this line is what i'm calling the debugging scaffolding i guess. System.out.println(array[i]) ; } } in this method if i set bug to true, wherever its being called from maybe by some kind of user imput, then i get the special debugging text to let me know what index the string being printed as at just in case i needed to know for the sake of my debugging (pretend a state of affairs exists where its helpful). All of my questions more or less boil down to the question: is this a good idea? but with a tad bit more objectivity: Is this an effective way to test my methods and debug them? i mean effective in terms of efficiency and not messing up my code. Is it acceptable to leave the if (bug) stuff ; code in place after i've got my method up and working? (if a definition of "acceptability" is needed to make this question objective then use "is not a matter of programing controversy such as ommiting brackets in an if(boolean) with only one line after it, though if you've got something better go ahead and use your definition i won't mind) Is there a more effective way to accomplish the gole of making debugging easier than what i'm doing? Anything you know i mean to ask but that i have forgotten too (as much information as makes sense is appreciated).

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  • How do I setup Linq to SQL and WCF

    - by Jisaak
    So I'm venturing out into the world of Linq and WCF web services and I can't seem to make the magic happen. I have a VERY basic WCF web service going and I can get my old SqlConnection calls to work and return a DataSet. But I can't/don't know how to get the Linq to SQL queries to work. I'm guessing it might be a permissions problem since I need to connect to the SQL Database with a specific set of credentials but I don't know how I can test if that is the issue. I've tried using both of these connection strings and neither seem to give me a different result. <add name="GeoDataConnectionString" connectionString="Data Source=SQLSERVER;Initial Catalog=GeoData;Integrated Security=True" providerName="System.Data.SqlClient" /> <add name="GeoDataConnectionString" connectionString="Data Source=SQLSERVER;Initial Catalog=GeoData;User ID=domain\userName; Password=blahblah; Trusted_Connection=true" providerName="System.Data.SqlClient" /> Here is the function in my service that does the query and I have the interface add the [OperationContract] public string GetCity(int cityId) { GeoDataContext db = new GeoDataContext(); var city = from c in db.Cities where c.CITY_ID == 30429 select c.DESCRIPTION; return city.ToString(); } The GeoData.dbml only has one simple table in it with a list of city id's and city names. I have also changed the "Serialization Mode" on the DataContext to "Unidirectional" which from what I've read needs to be done for WCF. When I run the service I get this as the return: SELECT [t0].[DESCRIPTION] FROM [dbo].[Cities] AS [t0] WHERE [t0].[CITY_ID] = @p0 Dang, so as I'm writing this I realize that maybe my query is all messed up?

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  • ConcurrentLinkedQueue$Node remains in heap after remove()

    - by action8
    I have a multithreaded app writing and reading a ConcurrentLinkedQueue, which is conceptually used to back entries in a list/table. I originally used a ConcurrentHashMap for this, which worked well. A new requirement required tracking the order entries came in, so they could be removed in oldest first order, depending on some conditions. ConcurrentLinkedQueue appeared to be a good choice, and functionally it works well. A configurable amount of entries are held in memory, and when a new entry is offered when the limit is reached, the queue is searched in oldest-first order for one that can be removed. Certain entries are not to be removed by the system and wait for client interaction. What appears to be happening is I have an entry at the front of the queue that occurred, say 100K entries ago. The queue appears to have the limited number of configured entries (size() == 100), but when profiling, I found that there were ~100K ConcurrentLinkedQueue$Node objects in memory. This appears to be by design, just glancing at the source for ConcurrentLinkedQueue, a remove merely removes the reference to the object being stored but leaves the linked list in place for iteration. Finally my question: Is there a "better" lazy way to handle a collection of this nature? I love the speed of the ConcurrentLinkedQueue, I just cant afford the unbounded leak that appears to be possible in this case. If not, it seems like I'd have to create a second structure to track order and may have the same issues, plus a synchronization concern.

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  • How to access method variables from within an anonymous function in JavaScript?

    - by Hussain
    I'm writing a small ajax class for personal use. In the class, I have a "post" method for sending post requests. The post method has a callback parameter. In the onreadystatechange propperty, I need to call the callback method. Something like this: this.requestObject.onreadystatechange = function() { callback(this.responseText); } However, I can't access the callback variable from within the anonomous function. How can I bring the callback variable into the scope of the onreadystatechange anonomous function? edit: Here's the full code so far: function request() { this.initialize = function(errorHandeler) { try { try { this.requestObject = new XDomainRequest(); } catch(e) { try { this.requestObject = new XMLHttpRequest(); } catch (e) { try { this.requestObject = new ActiveXObject("Msxml2.XMLHTTP"); //newer versions of IE5+ } catch (e) { this.requestObject = new ActiveXObject("Microsoft.XMLHTTP"); //older versions of IE5+ } } } } catch(e) { errorHandeler(); } } this.post = function(url,data) { var response;var escapedData = ""; if (typeof data == 'object') { for (i in data) { escapedData += escape(i)+'='+escape(data[i])+'&'; } escapedData = escapedData.substr(0,escapedData.length-1); } else { escapedData = escape(data); } this.requestObject.open('post',url,true); this.requestObject.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); this.requestObject.setRequestHeader("Content-length", data.length); this.requestObject.setRequestHeader("Connection", "close"); this.requestObject.onreadystatechange = function() { if (this.readyState == 4) { // call callback function } } this.requestObject.send(data); }

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  • How to detect the error raised on a particular codeline?

    - by infant programmer
    [Please edit the title if you find its not good enough] I have code which triggers XSL-transformation: objMemoryStream = new MemoryStream(); xslTransform = new XslCompiledTransform(); xpathXmlOrig = new XPathDocument("E:\\xslt error\\Simulation_of_error\\input.xml"); xslSettings = new XsltSettings(); xslSettings.EnableScript = true; xslTransform.Load(strXmlQueryTransformPath, xslSettings, new XmlUrlResolver()); xslTransform.Transform(xpathXmlOrig, null, objMemoryStream); objMemoryStream.Position = 0; StreamReader objStreamReader = new StreamReader(objMemoryStream); The method xslTransform.Load(strXmlQueryTransformPath, xslSettings, new XmlUrlResolver()); is a victim, which fails some times due to some time-out issue. I want to detect the failure of this codeline and execute again until it successfully executes! I tried using "TRY CATCH and WHILE methods": bool flag = true; do { try { xslTransform.Load(strXmlQueryTransformPath, xslSettings, new XmlUrlResolver()); flag = false; } catch { flag = true; } } while (flag); but the problem is "error is getting logged in the log file", Well. The whole code is under one more try statement, which I suspect is writing to log. Which is what I don't want... I don't want end user to know about the failure of this codeline. Is there anyway to get it done?

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  • Reducing moire when downsampling halftone comic images.

    - by drawnonward
    How can I reduce moire effects when downsampling halftone comic book images during live zoom on an iPhone or iPad? I am writing a comic book viewer. It would be nice to provide higher resolution images and allow the user to zoom in while reading the comic book. However, my client is averse to moire effects and will not allow this feature if there are noticeable moire artifacts while zooming, which of course there are. Modifying the images to be less susceptible to moire would only work if the modifications were not perceptible. Blur was specifically prohibited, as is anything that removes the beloved halftone dots. The images are black and white halftone and line art. The originals are 600 dpi but what we ship with the application will be half that at best, so probably 2500 pixels or less tall. So what are my options? If I write a custom downsampling algorithm would it be fast enough for real time on these devices? Are there other tricks I can do? Would it work to just avoid the size ratios that have the most visual moire effects? As you zoom in an out, there are definitely peaks where the moire effects are worst. Is there a way to calculate what those points are and just zoom to a nearby scale that is not as bad? Any suggestions are welcome. I have very little experience with image and signal processing, but am enjoying the opportunity to learn. I know nothing of wavelets and acutance and other jargon, so please be verbose.

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  • undefined reference to function, despite giving reference in c

    - by Jamie Edwards
    I'm following a tutorial, but when it comes to compiling and linking the code I get the following error: /tmp/cc8gRrVZ.o: In function `main': main.c:(.text+0xa): undefined reference to `monitor_clear' main.c:(.text+0x16): undefined reference to `monitor_write' collect2: ld returned 1 exit status make: *** [obj/main.o] Error 1 What that is telling me is that I haven't defined both 'monitor_clear' and 'monitor_write'. But I have, in both the header and source files. They are as follows: monitor.c: // monitor.c -- Defines functions for writing to the monitor. // heavily based on Bran's kernel development tutorials, // but rewritten for JamesM's kernel tutorials. #include "monitor.h" // The VGA framebuffer starts at 0xB8000. u16int *video_memory = (u16int *)0xB8000; // Stores the cursor position. u8int cursor_x = 0; u8int cursor_y = 0; // Updates the hardware cursor. static void move_cursor() { // The screen is 80 characters wide... u16int cursorLocation = cursor_y * 80 + cursor_x; outb(0x3D4, 14); // Tell the VGA board we are setting the high cursor byte. outb(0x3D5, cursorLocation >> 8); // Send the high cursor byte. outb(0x3D4, 15); // Tell the VGA board we are setting the low cursor byte. outb(0x3D5, cursorLocation); // Send the low cursor byte. } // Scrolls the text on the screen up by one line. static void scroll() { // Get a space character with the default colour attributes. u8int attributeByte = (0 /*black*/ << 4) | (15 /*white*/ & 0x0F); u16int blank = 0x20 /* space */ | (attributeByte << 8); // Row 25 is the end, this means we need to scroll up if(cursor_y >= 25) { // Move the current text chunk that makes up the screen // back in the buffer by a line int i; for (i = 0*80; i < 24*80; i++) { video_memory[i] = video_memory[i+80]; } // The last line should now be blank. Do this by writing // 80 spaces to it. for (i = 24*80; i < 25*80; i++) { video_memory[i] = blank; } // The cursor should now be on the last line. cursor_y = 24; } } // Writes a single character out to the screen. void monitor_put(char c) { // The background colour is black (0), the foreground is white (15). u8int backColour = 0; u8int foreColour = 15; // The attribute byte is made up of two nibbles - the lower being the // foreground colour, and the upper the background colour. u8int attributeByte = (backColour << 4) | (foreColour & 0x0F); // The attribute byte is the top 8 bits of the word we have to send to the // VGA board. u16int attribute = attributeByte << 8; u16int *location; // Handle a backspace, by moving the cursor back one space if (c == 0x08 && cursor_x) { cursor_x--; } // Handle a tab by increasing the cursor's X, but only to a point // where it is divisible by 8. else if (c == 0x09) { cursor_x = (cursor_x+8) & ~(8-1); } // Handle carriage return else if (c == '\r') { cursor_x = 0; } // Handle newline by moving cursor back to left and increasing the row else if (c == '\n') { cursor_x = 0; cursor_y++; } // Handle any other printable character. else if(c >= ' ') { location = video_memory + (cursor_y*80 + cursor_x); *location = c | attribute; cursor_x++; } // Check if we need to insert a new line because we have reached the end // of the screen. if (cursor_x >= 80) { cursor_x = 0; cursor_y ++; } // Scroll the screen if needed. scroll(); // Move the hardware cursor. move_cursor(); } // Clears the screen, by copying lots of spaces to the framebuffer. void monitor_clear() { // Make an attribute byte for the default colours u8int attributeByte = (0 /*black*/ << 4) | (15 /*white*/ & 0x0F); u16int blank = 0x20 /* space */ | (attributeByte << 8); int i; for (i = 0; i < 80*25; i++) { video_memory[i] = blank; } // Move the hardware cursor back to the start. cursor_x = 0; cursor_y = 0; move_cursor(); } // Outputs a null-terminated ASCII string to the monitor. void monitor_write(char *c) { int i = 0; while (c[i]) { monitor_put(c[i++]); } } void monitor_write_hex(u32int n) { s32int tmp; monitor_write("0x"); char noZeroes = 1; int i; for (i = 28; i > 0; i -= 4) { tmp = (n >> i) & 0xF; if (tmp == 0 && noZeroes != 0) { continue; } if (tmp >= 0xA) { noZeroes = 0; monitor_put (tmp-0xA+'a' ); } else { noZeroes = 0; monitor_put( tmp+'0' ); } } tmp = n & 0xF; if (tmp >= 0xA) { monitor_put (tmp-0xA+'a'); } else { monitor_put (tmp+'0'); } } void monitor_write_dec(u32int n) { if (n == 0) { monitor_put('0'); return; } s32int acc = n; char c[32]; int i = 0; while (acc > 0) { c[i] = '0' + acc%10; acc /= 10; i++; } c[i] = 0; char c2[32]; c2[i--] = 0; int j = 0; while(i >= 0) { c2[i--] = c[j++]; } monitor_write(c2); } monitor.h: // monitor.h -- Defines the interface for monitor.h // From JamesM's kernel development tutorials. #ifndef MONITOR_H #define MONITOR_H #include "common.h" // Write a single character out to the screen. void monitor_put(char c); // Clear the screen to all black. void monitor_clear(); // Output a null-terminated ASCII string to the monitor. void monitor_write(char *c); #endif // MONITOR_H common.c: // common.c -- Defines some global functions. // From JamesM's kernel development tutorials. #include "common.h" // Write a byte out to the specified port. void outb ( u16int port, u8int value ) { asm volatile ( "outb %1, %0" : : "dN" ( port ), "a" ( value ) ); } u8int inb ( u16int port ) { u8int ret; asm volatile ( "inb %1, %0" : "=a" ( ret ) : "dN" ( port ) ); return ret; } u16int inw ( u16int port ) { u16int ret; asm volatile ( "inw %1, %0" : "=a" ( ret ) : "dN" ( port ) ); return ret; } // Copy len bytes from src to dest. void memcpy(u8int *dest, const u8int *src, u32int len) { const u8int *sp = ( const u8int * ) src; u8int *dp = ( u8int * ) dest; for ( ; len != 0; len-- ) *dp++ =*sp++; } // Write len copies of val into dest. void memset(u8int *dest, u8int val, u32int len) { u8int *temp = ( u8int * ) dest; for ( ; len != 0; len-- ) *temp++ = val; } // Compare two strings. Should return -1 if // str1 < str2, 0 if they are equal or 1 otherwise. int strcmp(char *str1, char *str2) { int i = 0; int failed = 0; while ( str1[i] != '\0' && str2[i] != '\0' ) { if ( str1[i] != str2[i] ) { failed = 1; break; } i++; } // Why did the loop exit? if ( ( str1[i] == '\0' && str2[i] != '\0' || (str1[i] != '\0' && str2[i] =='\0' ) ) failed =1; return failed; } // Copy the NULL-terminated string src into dest, and // return dest. char *strcpy(char *dest, const char *src) { do { *dest++ = *src++; } while ( *src != 0 ); } // Concatenate the NULL-terminated string src onto // the end of dest, and return dest. char *strcat(char *dest, const char *src) { while ( *dest != 0 ) { *dest = *dest++; } do { *dest++ = *src++; } while ( *src != 0 ); return dest; } common.h: // common.h -- Defines typedefs and some global functions. // From JamesM's kernel development tutorials. #ifndef COMMON_H #define COMMON_H // Some nice typedefs, to standardise sizes across platforms. // These typedefs are written for 32-bit x86. typedef unsigned int u32int; typedef int s32int; typedef unsigned short u16int; typedef short s16int; typedef unsigned char u8int; typedef char s8int; void outb ( u16int port, u8int value ); u8int inb ( u16int port ); u16int inw ( u16int port ); #endif //COMMON_H main.c: // main.c -- Defines the C-code kernel entry point, calls initialisation routines. // Made for JamesM's tutorials <www.jamesmolloy.co.uk> #include "monitor.h" int main(struct multiboot *mboot_ptr) { monitor_clear(); monitor_write ( "hello, world!" ); return 0; } here is my makefile: C_SOURCES= main.c monitor.c common.c S_SOURCES= boot.s C_OBJECTS=$(patsubst %.c, obj/%.o, $(C_SOURCES)) S_OBJECTS=$(patsubst %.s, obj/%.o, $(S_SOURCES)) CFLAGS=-nostdlib -nostdinc -fno-builtin -fno-stack-protector -m32 -Iheaders LDFLAGS=-Tlink.ld -melf_i386 --oformat=elf32-i386 ASFLAGS=-felf all: kern/kernel .PHONY: clean clean: -rm -f kern/kernel kern/kernel: $(S_OBJECTS) $(C_OBJECTS) ld $(LDFLAGS) -o $@ $^ $(C_OBJECTS): obj/%.o : %.c gcc $(CFLAGS) $< -o $@ vpath %.c source $(S_OBJECTS): obj/%.o : %.s nasm $(ASFLAGS) $< -o $@ vpath %.s asem Hopefully this will help you understand what is going wrong and how to fix it :L Thanks in advance. Jamie.

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  • Atomic int writes on file

    - by Waneck
    Hello! I'm writing an application that will have to be able to handle many concurrent accesses to it, either by threads as by processes. So no mutex'es or locks should be applied to this. To make the use of locks go down to a minimum, I'm designing for the file to be "append-only", so all data is first appended to disk, and then the address pointing to the info it has updated, is changed to refer to the new one. So I will need to implement a small lock system only to change this one int so it refers to the new address. How is the best way to do it? I was thinking about maybe putting a flag before the address, that when it's set, the readers will use a spin lock until it's released. But I'm afraid that it isn't at all atomic, is it? e.g. a reader reads the flag, and it is unset on the same time, a writer writes the flag and changes the value of the int the reader may read an inconsistent value! I'm looking for locking techniques but all I find is either for thread locking techniques, or to lock an entire file, not fields. Is it not possible to do this? How do append-only databases handle this? Thanks! Cauê

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