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• What's a good way to detect wrap-around in a fixed-width message counter?

  - by Kristo

  I'm writing a client application to communicate with a server program via UDP. The client periodically makes requests for data and needs to use the most recent server response. The request message has a 16-bit unsigned counter field that is echoed by the server so I can pair requests with server responses. Since it's UDP, I have to handle the case where server responses arrive out of order (or don't arrive at all). Naively, that means holding on to the highest message counter seen so far and dropping any incoming message with a lower number. But that will fail as soon as we pass 65535 messages and the counter wraps back to zero. Is there a good way to detect (with reasonable probability) that, for example, message 5 actually comes after message 65,000? The implementation language is C++.

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• .NET security: how to check if a method is allowed to execute under current user's perrmissions

  - by Gart

  Given an ASP.NET MVC Controller class declaration: public class ItemController : Controller { public ActionResult Index() { // ... } public ActionResult Details() { // ... } [Authorize(Roles="Admin, Editor")] public ActionResult Edit() { // ... } [Authorized(Roles="Admin")] public ActionResult Delete() { // .. } } I need to reflect a list of methods in this class which may be invoked with the current user's permissions. The [Authorized] attribute is specific to ASP.NET MVC, and this is only an example. I would prefer a universal solution for this problem which works for any .NET class. Please share some ideas of what could be done in this case.

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• Check result of AX_PYTHON_MODULE in configure.ac

  - by tmatth

  In using the m4_ax_python_module.m4 macro in configure.ac (AX_PYTHON_MODULE), one can know at configure time if a given module is installed. It takes two arguments, the module name, and second argument which if not empty, will lead to an exit, useful when the module is a must-have. In the case where you don't want a fatal exit, how do you test in configure.ac which modules were found or not? They output "yes" or "no" when configure is run, but that's all I've found so far. Basically If I have these lines in configure.ac: AX_PYTHON_MODULE(json,[]) AX_PYTHON_MODULE(simplejson,[]) How do I test which of the two modules were found? See http://www.gnu.org/software/autoconf-archive/ax_python_module.html#ax_python_module for documentation about this macro.

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• Using the C Cluster library in Visual C++.

  - by Stefan K.

  Right so i'm trying to use a C library in C++, never actually done this before i thought it would be a case of declaring the header includes under a extern "C" and setting the compile as flag to "default" but i'm still getting linker errors and think that the header file might have to be complied as a DLL. I have no idea really. Is it the library that's the problem or is it me? There are some make files in the cluster-1.47\src, but i don't know how or if they relate to "cluster.h". I've uploaded a visual studio 2008 project for anyone to take a gander, any help would be appreciated as i've been hitting my head against the wall for time now. thanks Stefan Link to Visual Studio 2008 Project

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• Equivalent of Switch Statement in MySql 5

  - by Robert Gowland

  Using MySql 5, I have a task where I need to update one table based on the contents of another table. For example, I need to add 'A1' to table 'A' if table 'B' contains 'B1'. I need to add 'A2a' and 'A2b' to table 'A' if table 'B' contains 'B2', etc.. In our case, the value in table 'B' we're interested is an enum. Right now I have a stored procedure containing a series of statements like: INSERT INTO A SELECT 'A1' FROM B WHERE B.Value = 'B1'; --Repeat for 'B2' -> 'A2a', 'A2b'; 'B3' -> 'A3', etc... Is there a nicer more DRY way of accomplishing this?

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• In C#, What is <T> After a Method Declaration?

  - by Drew

  I'm a VB.Net guy. (because I have to be, because the person who signs my check says so. :P) I grew up in Java and I don't generally struggle to read or write in C# when I get the chance. I came across some syntax today that I have never seen, and that I can't seem to figure out. In the following method declaration, what does < T represent? static void Foo < T (params T[] x) I have seen used in conjunction with declaring generic collections and things, but I can't for the life of me figure out what it does for this method. In case it matters, I came across it when thinking about some C# brain teasers. The sixth teaser contains the entire code snippet.

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• Using member variables inherited from a templated base class (C++)

  - by Aaron Becker

  I'm trying to use member variables of a templated base class in a derived class, as in this example: template <class dtype> struct A { int x; }; template <class dtype> struct B : public A<dtype> { void test() { int id1 = this->x; // always works int id2 = A<dtype>::x; // always works int id3 = B::x; // always works int id4 = x; // fails in gcc & clang, works in icc and xlc } }; gcc and clang are both very picky about using this variable, and require either an explicit scope or the explicit use of "this". With some other compilers (xlc and icc), things work as I would expect. Is this a case of xlc and icc allowing code that's not standard, or a bug in gcc and clang?

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• What's the best way of using a pair (triple, etc) of values as one value in C#?

  - by Yacoder

  That is, I'd like to have a tuple of values. The use case on my mind: Dictionary<Pair<string, int>, object> or Dictionary<Triple<string, int, int>, object> Are there built-in types like Pair or Triple? Or what's the best way of implementing it? Update There are some general-purpose tuples implementations described in the answers, but for tuples used as keys in dictionaries you should additionaly verify correct calculation of the hash code. Some more info on that in another question. Update 2 I guess it is also worth reminding, that when you use some value as a key in dictionary, it should be immutable.

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• What video codecs have most amount of content and thus popular at present/in future?

  - by goldenmean

  Hi, I want to find out if I can get some data on the percentage wise distribution of video content, for different video codecs currently used for video encoding. I know there are different applications/use-case scenarios which have different encoder used but i want to consdier all that and have a overall usage number(%) My guess is(highest to lowest % of content) - H.264(AVC) DivX MPEG2 VP6 Where do H.263, MPEG4, VC-1, RV, Theora, etc. fit in here. How may this look like in future? PS:I would like this to be community wiki to have get wider range of inputs, if someone with privileges can do it for me please. thank you. -AD

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• Razor View Engine and jQuery

  - by rjovic

  Hi, does anybody know how to force Razor View engine to print exact line which is under foreach loop. Code follows : @section head{ <script type="text/javascript" src="@Url.Content("~/Content/Scripts/jquery-1.4.1.js")"></script> <script type="text/javascript" src="@Url.Content("~/Content/Scripts/jquery.progressbar.min.js")"></script> <script type="text/javascript"> $(document).ready(function() { @foreach(var player in Model) { jQuery("#pb@PlayerID").progressBar(); } }); </script> } I tried using $() and jQuery() but in both case razor don't know what to do. Is there any way to force him to print exact this : jQuery("#pb@PlayerID").progressBar(); . I want to have something like this : $(document).ready(function() { $("#pb1").progressBar(); $("#pb2").progressBar(); $("#pb3").progressBar(); }); Thank you in advance!

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• I want to use facebook connect in my website to register, login and comment on news articles or posts made by other users

  - by sasi kiran

  I would like to implement the following things in my website. I have done some extensive search over the internet but couldnt find and specific examples on how to implement them I am developing this site in php using a mvc framework Would like to have facebook registration on my website - users who have an account in facebook will get an option to use the details to register in my site, using their authentication I would pull the relavant details from their account and create a new account for them in my website. I would like to use facebook register fbml/fbjs in this case Would like to have facebook login used to login into my site. How to use the sessions is what I would like to know? I would like to make posts to the facebook-wall of the users registered in my site. Also if possible sent messages to them through my code whenever a new post is made to my site. Thanks for your help.

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• How can I get the element in which highlighted text is in?

  - by Koes Bong

  I am trying to learn how to write a bookmarklet where I can highlight some text, click on the bookmarklet and have it tell me what got highlighted. I can get that far, but next I want to know what element that text is in. For example: <div id="some-id">to be highlighted</div> The bookmarklet code: javascript:(function(){alert(window.getSelection();})() If I highlight the text "to be highlighted" and then click on the bookmarklet, it will alert the text. But how can I get the element in which the text is in, in this case the element after that? So the flow is: highlight text, click bookmarklet, bookmarklet tells you what you highlighted and the element it's in. Thanks!

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• Method return values and exceptions

  - by dnagirl

  I have an interface called iIncident which defines a single method when(). when() should return a DateTime object. I'm trying to decide what to do if $object->when() has no DateTime to return as might be the case just after an object is instantiated and before all its properties are set. My choices are: return false throw some kind of Exception return some default DateTime like '9999-01-01' My inclination is to go with an Exception since $object really can't act as an incident until it knows when it occurred. I don't want to return a default DateTime because it complicates comparisons and it's not true. And I don't really want to return false because then I have to check for it every time I call the method- but if that is the preferred method, I guess I will. Is throwing an exception the best way? And is there a predefined exception type I should use (none of the SPL ones struck me as particularly appropriate- but that might just indicate my lack of experience)?

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• Retrieve Storage and Programs Memory on .NET Compact Framework 2 and WM5

  - by wintermute

  Hi! I've been looking for quite a while already and still couldn't find a solution for this. All I need is to retrieve the memory levels and percentage of use. OpenNETCF has a MemoryManagement class, which seems to encapsulates a data structure returned through a P/Invoke or something like that, and it gives me the TotalPhysicalMemory, TotalVirtualMemory, AvailablePhisicalMemory and such, but those do not directly relate to Storage and Programs, nor could I find a way to "convert" these attributes to those I need. Has anyone there already done this? It must be easy, I just need the very same values available on Settings System Memory. Thanks in advance! edit: I'm already being able to retrieve Available and total Storage memory through the GetDiskFreeSpaceEx P/Invoke. Since Storage and Programs memory seem to rely into the same hardware, maybe it's just a case of finding out what path to pass as the method's first parameter.

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• ns-2 c++ file changes

  - by stanigator

  I have just installed a network simulator program called ns-2 and I am trying to familiarize myself with it by going through the tutorial by Marc Greis. When I get to the stage where I'm messing around with C++ source files and related program C++ source files as stated in http://www.isi.edu/nsnam/ns/tutorial/index.html, I don't know what to do as there are enough inconsistencies between the version of ns-2 that I downloaded (which is the latest stable build) and the guide. What would your recommendations in this case, as I don't know what to do with it as a newbie? Thanks in advance for your help!

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• How can CSS stop Google Maps loading?

  - by AP257

  I have a page with a Google Maps div: <div id="map_canvas" style="width: 100%; height: 332px;" ></div> If I comment out my CSS, the map loads fine: if I include the CSS, the map controls load, but the map tiles don't load: there's just a grey background. This is the case even if I put the map div just after the <body> tag, not within any styled element at all. No CSS, it loads fine. With CSS, no map. Does anyone know what could be causing this? I don't quite understand what the problem can be if no CSS styles are being applied to any element that contains the map. If more diagnostics are needed, please let me know, and I'll deploy the broken map onto a staging site, so people can look at the source.

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• Get expiration time of a memcache item in php?

  - by Jonatan Littke

  Hey. I'm caching tweets on my site (with 30 min expiration time). When the cache is empty, the first user to find out will repopulate it. However, at that time the Twitter API may return a 200. In that case I'd like to prolong the previous data for another 30 mins. But the previous data will already be lost. So instead I'd like to look into repopulating the cache, say, 5 minutes before expiration time so that I don't lose any date. So how do I know the expiration time of an item when using php's memcache::get()? Also, is there a better way of doing this?

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• Environment variable (NLS_LANG) value altered in Java process?

  - by Ralkie

  This was noticed in some legacy Java application (jre1.4 on HP-UX). Parent process (shell script S1) is starting Java process, which on its own is starting child process (shell script S2). Schematically it's: S1 Java S2. NB! Java application connects to Oracle DB using OCI driver. What is strange here is that process running S1 has environment variable NLS_LANG set to american_america.BLT8MSWIN1257, Java spawns S2 using: Runtime.getRuntime().exec(cmd); and S2 shows that NLS_LANG is set to american_america.UTF8 (!) This happens on some limited-access environment (production), I was not able to reproduce same problem on linux with jre 1.5. AFAIK, Java process should inherit environment from its parrent (S1) and should pass all environment variables to its child S2 (since single argument exec call was used). However, it does not seem to be the case. Any ideas why NLS_LANG appears to be altered?

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• Bash variable kills script execution

  - by Kyle Terry

  Sorry if this is better suited at serverfault, but I think it learns more towards the programming side of things. I have some code that's going into /etc/rc.local to detect what type of touch screen monitor is plugged in and changes out the xorg.conf before launching X. Here is a small snippet: CURRENT_MONITOR=`ls /dev/usb | grep 'egalax_touch\|quanta_touch'` case $CURRENT_MONITOR in '') CURRENT_MONITOR='none' ;; esac If one of those two touch screens is plugged in, it works just fine. If any other monitor is plugged in, it stops at the "CURRENT_MONITOR=ls /dev/usb | grep 'egalax_touch\|quanta_touch'." For testing I touched two files. One before creating CURRENT_MONITOR and one after CURRENT_MONITOR and only file touched before is created. I'm not a bash programmer so this might be something very obvious.

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• Problem with updating multiple rows which are in conflict with unique index

  - by GUZ

  I am using Microsoft SQL Server and I have a master-detail scenario where I need to store the order of details. So in the Detail table I have ID, MasterID, Position and some other columns. There is also a unique index on MasterID and Position. It works OK except one case: when I have some existing details and I change their order. For example when I change a detail on position 3 with a detail on position 2. When I save the detail on position 2 (which in the database has Position equal to 3) SQL Server protests, because the index uniqueness constraint. How to solve this problem in a reasonable way? Thank you in advance Lukasz Glaz

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• C# property in a form class only accessable after formload event

  - by Spooky2010

  using vs2008, c# Howdy, Im instantiating and calling Form B from Form A. FormB has some custom properties, to allow me to pass it things like sqlAdaptors and dataset instances. When i instantiate and show Form B from Form A as a dialog form with a Using statement, it all works fine, but i find the properties i pass are not available in Form B until after the form_load event has fired. I was under the impression the properties when passed to a instantiated class should be available from a constructor, but this is not the case. If it try to access the properties before the form load event i get a null reference exception. Is this correct behavior ? It is very annoying. thanks for any help

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• does a ruby on rails rack class get access to the entire rails environment?

  - by Andrew Arrow

  that is when the def call(env) method is invoked by hitting any url, can I inside that method make some ActiveRecord queries, use classes defined in lib, etc. etc. Or is it more like an irb console without the rails env loaded? Another way to put it with a rake task example: task :foo => :environment do # with env end task :foo2 do # without env end I would think rack classes would NOT get the environment so they are super fast and don't take all the overhead of a normal rails request. But that doesn't seem to be the case. I CAN make ActiveRecord queries inside my rack class. So what is the advantage of rack then?

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• Advantages of using a Dynamic Client with JAX-WS

  - by jconlin

  What are the advantages of using a dynamic client with JAX-WS services as opposed to just using generated client classes? What are the disadvantages? **For my particular case I am using Apache CXF, I'm not sure what other libraries allow "dynamic" clients. -I thought I didn't need to add this, but... I'm looking for non-obvious(I know...subjective) advantages. I don't need someone else to tell me that an advantage of not using generated classes is that I don't need to generate classes.

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• MongoDB map/reduce counts

  - by ibz

  The output from MongoDB's map/reduce includes something like 'counts': {'input': I, 'emit': E, 'output': O}. I thought I clearly understand what those mean, until I hit a weird case which I can't explain. According to my understanding, counts.input is the number of rows that match the condition (as specified in query). If so, how is it possible that the following two queries have different results? db.mycollection.find({MY_CONDITION}).count() db.mycollection.mapReduce(SOME_MAP, SOME_REDUCE, {'query': {MY_CONDITION}}).counts.input I thought the two should always give the same result, independent of the map and reduce functions, as long as the same condition is used.

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• How to determine the end of an integer array when manipulating with integer pointer?

  - by AKN

  Here is the code: int myInt[] ={ 1, 2, 3, 4, 5 }; int *myIntPtr = &myInt[0]; while( *myIntPtr != NULL ) { cout<<*myIntPtr<<endl; myIntPtr++; } Output: 12345....<junks>.......... For Character array: (Since we have a NULL character at the end, no problem while iterating) char myChar[] ={ 'A', 'B', 'C', 'D', 'E', '\0' }; char *myCharPtr = &myChar[0]; while( *myCharPtr != NULL ) { cout<<*myCharPtr<<endl; myCharPtr++; } Output: ABCDE My question is since we say to add NULL character as end of the strings, we rule out such issues! If in case, it is rule to add 0 to the end of integer array, we could have avoided this problem. What say?

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