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  • abstract class MouseAdapter vs. interface

    - by Stefano Borini
    I noted this (it's a java.awt.event class). public abstract class MouseAdapter implements MouseListener, MouseWheelListener, MouseMotionListener { .... } Then you are clearly forced to extend from this adapter public class MouseAdapterImpl extends MouseAdapter {} the class is abstract and implements no methods. Is this a strategy to combine different interfaces into a single "basically interface" ? I assume in java it's not possible to combine different interfaces into a single one without using this approach. In other words, it's not possible to do something like this in java public interface MouseAdapterIface extends MouseListener, MouseWheelListener, MouseMotionListener { } and then eventually public class MouseAdapterImpl implements MouseAdapterIface {} Is my understanding of the point correct ? what about C# ?

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  • What is the JavaScript variable scope in a switch / case statment?

    - by Todd Moses
    While creating JavaScript with ASP.NET MVC I noticed several scope warnings and realized that I am missing something with understanding the variable scope inside the switch / case statement. Warning: 'i' is already defined referring to case b and case c My code looks similar to this: switch(element) { case 'a': for(var i=0; i < count; i++){ do something } break; case 'b': for(var i=0; i < count; i++){ do something } break; case 'c': for(var i=0; i < count; i++){ do something } break; } I thought scope ended with each break statement but it seems that scope does not end until the end of the switch/case. Is scope for the entire switch/case?

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  • Best way to return a user-generated file, AJAX or Forms?

    - by Bill Zimmerman
    Hi, I'm new to web programming, so I need some help. I am writing a custom file-creation app for my site. A user visits the page, clicks on some various options and toggles some checkboxes, and the presses a 'download now' link. I have a PHP backend which will be processing the submission, and generating a PDF file. After the user presses the download link, I want the download to start like it would for any static link. My question is: What is the best way to do this? From my limited understanding, I have a choice between using AJAX or somehow using forms to submit the data. What are the advantages/disadvantages of each? Does anyone have any good links to examples? Thanks

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  • Implementing password hashing/salting algorithm from crackstation.net

    - by Mason240
    I am trying to implement a password hashing/salting algorithm from crackstation.net, but I am unsure how implement it. Storing the password upon user registration seems to be as simple as passing the password into create_hash(). $password = create_hash($_POST['Password']; I'm not following how to validate upon user login. validate_password($password, $good_hash) returns either true or false, and takes $password as parameter, so it seems like a no brainer except for the second parameter $good_hash. Where does this param come from? It is my understanding that password is turned into a hash value every time its used, and that the hash value is what is stored and compared. So why would I have both the $password and $good_hash values? Quick overview of the functions: function create_hash($password){ calls pbkdf2() } function validate_password($password, $good_hash){ calls pbkdf2() calls slow_equals() } function slow_equals($a, $b){ } function pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output = false){ } Of course a different, better method for this would also be just as helpful. Thank you

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  • I need help translating this portion of the ECMAScript grammar?

    - by ChaosPandion
    I've been working on my own implementation of ECMAScript for quite some time now. I have basically done everything by hand to help gain a deep understanding of the process. Repeated attempts to analyze and understand this portion of the grammar have failed so I've been working on the run time instead. Now I am at a point were I will be working on object literals so I really need to polish my syntactic analyzer. Can anyone put this in terms a language parser novice could understand? My biggest source of confusion is the following: new MemberExpression Arguments This is supposed to be a member expression, but this seemingly conflicts with the following: NewExpression : MemberExpression new NewExpression Is a new expression a member expression or a left hand side expression? To be honest I am having trouble laying out the proper C# classes for the concrete grammar. MemberExpression : PrimaryExpression FunctionExpression MemberExpression [ Expression ] MemberExpression . IdentifierName new MemberExpression Arguments NewExpression : MemberExpression new NewExpression CallExpression : MemberExpression Arguments CallExpression Arguments CallExpression [ Expression ] CallExpression . IdentifierName LeftHandSideExpression : NewExpression CallExpression

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  • Are Scala "continuations" just a funky syntax for defining and using Callback Functions?

    - by Alex R
    And I mean that in the same sense that a C/Java for is just a funky syntax for a while loop. I still remember when first learning about the for loop in C, the mental effort that had to go into understanding the execution sequence of the three control expressions relative to the loop statement. Seems to me the same sort of effort has to be applied to understand Continuations (in Scala and I guess probably other languages). And then there's the obvious follow-up question... if so, then what's the point? It seems like a lot of pain (language complexity, programmer errors, unreadable programs, etc) for no gain.

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  • Why isn't Hadoop implemented using MPI?

    - by artif
    Correct me if I'm wrong, but my understanding is that Hadoop does not use MPI for communication between different nodes. What are the technical reasons for this? I could hazard a few guesses, but I do not know enough of how MPI is implemented "under the hood" to know whether or not I'm right. Come to think of it, I'm not entirely familiar with Hadoop's internals either. I understand the framework at a conceptual level (map/combine/shuffle/reduce and how that works at a high level) but I don't know the nitty gritty implementation details. I've always assumed Hadoop was transmitting serialized data structures (perhaps GPBs) over a TCP connection, eg during the shuffle phase. Let me know if that's not true.

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  • Programming a loopback-device consisting of several files in Linux

    - by dubbaluga
    Hej, it is relatively easy to use a file for emulating a block-device using losetup in Linux: http://www.walkernews.net/2007/07/01/create-linux-loopback-file-system-on-disk-file/ Can anyone please give me a hint on what to look for in case I want to program my own block-device which is based on several files I'm taking content from? For your understanding, I would like to let's say take bytes 1-500 and 1.000-3.000 from file1 and bytes 501-999 and bytes 3.001 to 5.000 from file2 to offer them as a combined block-device. My prefered programming language is Python and I want to write my program in user-space as much as possible. For Windows I found such an implementation. It's called FileDisk and HttpDisk and it can be found here: http://www.acc.umu.se/~bosse/ Thanks in advance and regards, Rainer

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  • iPhone: Cannot get simulator to generate .gcda profiling data files.

    - by Derek Clarkson
    I'm attempting to profile my code using the iPhone simulator. I've enabled Generate Test Coverage File and Instrument Program Flow and added -lgcov to the linker flags. According to everything I've read that should be all I need to do in terms of setup. Executing the program I can see the .gcno files appearing along side the .o compiled code in the build/.build/Debug-iphonesimulator/.build/Objects-normal/i386 directory. But when I run the app in the simulator I do not get any *.gcda files appearing. My understanding is that these files contain the data from the instrumentation. But I cannot find them anywhere on the computer. I know they can be produced and appear along side the *.gcno files because I have an old trashed buil directory which does have them. I just cannot figure out what I have to do to get them to appear and record the run. Any help appreciated.

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  • How do I use SDl_Threads properly?

    - by Anoymonous
    I am new to threads,SDL and how graphic work in general. I've been looking through all of LazyFoo's SDL tutorials, and had helped me greatly. But in his tutorials about multi threading, he commented that you should never use video functions in separate threads, or might cause problem. I am curious how it should be done, as I still have a vague understanding of graphics and threads. As one of my projects is a shoot'em up, I was wondering if I should create one thread that displays all the graphics, one threads receives all the player input for his ship, and another thread for the enemy AI. If this is NOT how it should be done, (I think it's wrong) does anyone have any advice of how graphics should be implemented with user input and enemy AI with threads? For the Lazyfoo's tutorials, this is the link: http://lazyfoo.net/SDL_tutorials/

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  • MDX: How To Aggregate Hierarchy Level Members With Same Name

    - by Dave Frautnick
    Greetings, I am new to MDX, and am having trouble understanding how to perform an aggregation on a hierarchy level with members that have the same names. This query is particular to Microsoft Analysis Services 2000 cubes. I have a given hierarchy dimension with levels defined as follows: [Segment].[Flow].[Segment Week] Within the [Segment Week] level, I have the following members: [Week- 1] [Week- 2] [Week- 3] ... [Week- 1] [Week- 2] [Week- 3] The members have the same names, but are aligned with a different [Flow] in the parent level. So, the first occurrence of the [Week- 1] member aligns with [Flow].[A] while the second occurrence of [Week- 1] aligns with [Flow].[B]. What I am trying to do is aggregate all the members within the [Segment Week] level that have the same name. In SQL terms, I want to GROUP BY the member names within the [Segment Week] level. I am unsure how to do this. Thank you. Dave

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  • how to pass an arbitrary signature to Certifcate

    - by eskoba
    I am trying to sign certificate (X509) using secret sharing. that is shareholders combine their signatures to produce the final signature. which will be in this case the signed certificate. however practically from my understanding only one entity can sign a certificate. therefore I want to know: which entities or data of the x509certificate are actually taken as input to the signing algorithm? ideally I want this data to be signed by the shareholders and then the final combination will be passed to the X509certificate as valid signature. is this possible? how could it done? if not are they other alternatives?

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  • Retrieving/simulating run-time "layer" functionality in Flash under ActionScript 3.

    - by Triynko
    Are there any AS3 classes to help arrange objects into layers, like in the designer, such that the objects all have the same parent? Obviously, I can use container clips to simulate layers, but I specifically want this kind of functionality for objects that have the same parent. My understanding is that the design-time notion of layers does not exist at run-time, and objects just have a depth index. I'm creating a class to simulate layering functionality with a single parent, but if one already exists, I'd like to check it out. On a side note... how do design-time layer masks manifest themselves at runtime in AS3? I thought maybe all objects on the masked layer share the same mask object, but the "mask" property appears to be null for all objects on the masked layer, even though they share the same parent timeline as the unmasked objects (i.e. unmasked layer object parent == masked layer object parent; therefore, no masked subcontainers appear to be in use).

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  • What is the best way to get support from microsoft developers [closed]

    - by Malcolm Frexner
    I have a problem at my production web, that I am not able to solve. I am not able to reproduce the problem in stage or development. It only appears when the website is under heavy load. I think it is solvable if somebody who has a very good understanding of the internals of FormsAuthentication would have a look at it by logging into our system. It should be at least Scottgu! Somebody told me that Microsoft Premier Support is a good choice for this kind of problems. We have no MSDN subscription or other connection to microsoft that enables us to use MPS. Is there a way to get support on a incident base? Are there other ways to get this kind of support? EDIT Here is the problem itself: http://stackoverflow.com/questions/2448720/different-users-get-the-same-cookie-value-in-aspxanonymous

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  • ASP.NET Temporary Folders - growing uncontrollably

    - by Sriram
    On our production server, we find that the ASP.NET Temporary folders grow uncontrollably. It reaches as much as 14Gb. When we check the folder content, we find couple of assemblies being created again and again in the folder. What could be possible reasons for this duplication? As per our understanding, compiled ASP assemblies goes into temporary folders - so what could be reasons for some of these assemblies getting duplicated in these temporary folders? What possible fixes (other than IIS Reset or changing web.config etc. - causing delete of all these files) can we look forward to implementing?

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  • Mobile Specific Site Development. Where to start?

    - by Andy
    I'm beginning the process of learning the ins and outs of developing sites for mobile web browsers. Are there any good resources/communities online that discuss mobile specific site development issues? My initial understanding is that to cover different phones you need to build one site that is enabled for browsers with the webkit engine (iphone, android, etc.) and another more basic site for other older browsers, is this assumption correct? Also what does developing for webkit mean exactly? How is it different than just using javascript/css/html? Is it the same except that you limit yourself to webkit specific functions and css? I looked on the webkit site, but it didn't explain it in those terms. Are there any other snafus I need to watch out for when developing for mobile browsers?

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  • Identifying iPhone OS's on a Network and Sending Push Notifications

    - by portalservices
    tldr; Can you identify devices on your network as an iPhone OS device easily? Can you send push notifications to devices identified as using the iPhone OS on your network without a a target app? Is is possible to identify which devices on a network are using the iPhone OS? With this information, is it possible to send push notifications to these devices? From my understanding, your application server will contact APNs, which will contact the users. So, the above would be impossible. Can someone confirm this for me? Thanks, P.S.

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  • Arrays in database tables and normalization

    - by Ivan Petrov
    Hi! Is it smart to keep arrays in table columns? More precisely I am thinking of the following schema which to my understanding violates normalization: create table Permissions( GroupID int not null default(-1), CategoryID int not null default(-1), Permissions varchar(max) not null default(''), constraint PK_GroupCategory primary key clustered(GroupID,CategoryID) ); and this: create table Permissions( GroupID int not null default(-1), CategoryID int not null default(-1), PermissionID int not null default(-1), constraint PK_GroupCategory primary key clustered(GroupID,CategoryID) ); UPD: Forgot to mention, in the scope of this concrete question we will consider that the "fetch rows that have permission X" won't be performed, instead all the lookups will be made by GroupID and CategoryID only Thoughts? Thanks in advance!

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  • jQuery internals: Organization of the jQuery Object

    - by sonofdelphi
    I was going through the source code of jQuery. I'm having trouble understanding the wrapping strategy for the jQuery object. (function( window, undefined ) { // Define a local copy of jQuery var jQuery = function( selector, context ) { // The jQuery object is actually just the init constructor 'enhanced' return new jQuery.fn.init( selector, context ); }, .... .... .... // Expose jQuery to the global object window.jQuery = window.$ = jQuery; })(window); Specifically, what I'm not able to understand stems from the first line. What is the outermost unnamed container function? Why is it required? Why is the container function anonymous? What is the need for the outermost '(' parantheses ?

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  • How do I get a right outer join in L2E?

    - by Dan
    I have two tables that I set up through the VS Entity Data Model Diagram tool. I'm trying to do a right outer join and it doesn't return results from the 2nd table. I have set up a 0..1 to MANY relationship from the diagram tool. When I run a Linq-To-Entities query, it still defaults to an INNER JOIN. From my understanding of entities, if I set up the relationship using VS, when I join the tables, it should automagically figure out the join syntax based on the relationship I supply. It doesn't seem to be doing that. I am using EF v1 (not Linq-to-Sql). Query I'm running: from s in SomeTable join t in SomeOtherTable on s.ID equals t.ID select new { s.MyFieldName, t.MyOtherFieldName }

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  • Handling ID's with db4o and ASP.NET MVC2

    - by Craig McGuff
    So, i'm looking at the TekPub sample for ASP.NET MVC2 (http://mvcstarter.codeplex.com/) using DB4o and there are a bunch of templates to create controllers etc, the generated code looks like: public ActionResult Details(int id) { var item = _session.Single<Account>(x=>x.ID == id); return View(item); } Now, my understanding is that using DB4o or a simliar object database that ID's are not required, so how/what exactly do I pass to enable this kind of templated code to function? UPDATE: Both answers were useful, I have modifed the templates to use GUID as the ID. I will add any relevant code/notes here once I see how it works out.

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  • car and cdr in scheme is driving me crazy ...

    - by kristian Roger
    Hi Im facing a probem with the car and cdr functions for example: first I defined a list caled it x (define x (a (bc) d ( (ef) g ) )) so x now is equal to (a (bc) d ( (ef) g ) now for example I need to get the g from this list using only car and cdr (!! noshortcuts as caddr cddr !!) the correct answer is: (car(cdr(car(cdr(cdr(cdr x)))))) BUT how ? :-( I work according to the rule (the car gives the head of list and cdr gives the tail) and instead of getting the answer above I keep reaching wronge answers can any one help me in understanding this ... give me step or a way to solve it step by step thanx in advance Im really sick of scheme language.

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  • convert int to string for use in allegro function

    - by ace
    I am trying to run the following code using allegro. textout_ex(screen, font, numbComments , 100, 100, GREEN, BLACK); numbComments is an integer, the function prototype of this function is void textout_ex(BITMAP *bmp, const FONT *f, const char *s, int x, int y, int color, int bg); and i cannot, according to my understanding pass this integer in the third position. I therefore need to convert the integer into a string. I did it like this, but it didnt work. Help please? int score = numbComments; string Str; stringstream out; // YOU MUST INCLUDE <sstream> FOR THIS. out << score; Str = out.str(); and then tried to use the string Str, which didnt work

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  • What are the pre-requisites to become a Business Developer

    - by T.Raghavendra
    I am not sure if this is the right portal, But i believe many entrepreneurs are available here. I wanted to know how can someone get in to business development. what are the factors that are necessary if the person has no MBA degree. is it possible to get into such profession. I mean is it just the fact you must know how to write RFP, or estimates. Understanding client requirements and getting them the best available solution. Please guide me as I am interested, with 5+ years of industry experience is it possible to move to different domain.

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  • Backup AWS Dynamodb to S3

    - by Ali
    It has been suggested on Amazon docs http://aws.amazon.com/dynamodb/ among other places, that you can backup your dynamodb tables using Elastic Map Reduce, I have a general understanding of how this could work but I couldn't find any guides or tutorials on this, So my question is how can I automate dynamodb backups (using EMR)? So far, I think I need to create a "streaming" job with a map function that reads the data from dynamodb and a reduce that writes it to S3 and I believe these could be written in Python (or java or a few other languages). Any comments, clarifications, code samples, corrections are appreciated.

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