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• Cookies concept

  - by Chinna

  How to disable or clear the client browser Cookies using any technology may i think using javascript it will be usable to any techonology

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• How the websocket bi-directional concept work?

  - by GMsoF

  I think the main difference between websocket and http streaming (I am not refering to polling and long polling) is websocket allows bi-directional communication which is similar to usual raw socket programming. (above is my understanding, could be wrong, feel free to correct me.) My question is how the web client (browser) continue to send another request in the already-opened websocket? Usual http request will treat another request as new socket connection, but websocket does not, that is why I am confused, how it achieve that? It should be handled in Server side or Client (browser) side?

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• backbonejs remove anomaly concept

  - by user1537158

  I was building a small app for adding and deleting li from ul using Backbonejs.One of the SO members cymen helped me code it, using that i tailored the code a little.currently if i add one element and delete , it works , but the second time i add an element (to ul) and go to delete it , i get Uncaught TypeError: Cannot call method 'remove' of undefined Pasting my code here , HTML : <input type="text" id="name"> <button id="add">Add</button> <ul id="mylist"></ul> JS: $(function(){ var myCollection = Backbone.Collection.extend(); var myView = Backbone.View.extend({ el:$('body'), tagName:'li', initialize : function(e){ this.collection.bind("add",this.render,this); this.collection.bind("remove",this.render,this); }, events:{ 'click #add' : 'addfoo' }, addfoo : function(){ var myname= $('#name').val(); $('#name').val(''); this.collection.add({name:myname}); }, render : function(){ $('#mylist').empty(); this.collection.each(function(model){ console.log("myView"); var remove = new myRemoveView({model:model}); remove.render(); }); } }); var myRemoveView = Backbone.View.extend({ el:$('body'), events:{ 'click .button':'removeFoo' }, removeFoo : function(){ console.log("here"); this.model.collection.remove(this.model); }, render : function(){ console.log("second view"); $('#mylist').append('<li>'+this.model.get('name') + "<button class='button'>"+"delete"+"</button></li>"); return; } }); var view = new myView({collection: new myCollection()}); }); Two things i did not understand : i) in the removeFoo function , we write this.model.collection.remove(this.model) shouldnt this have been this.collection.model.remove , something of that sort ? ii) i add a li to ul , then i delete it , when i add another li (appending to ul works perfect) but this time when i go to delete it throws me the above error : Uncaught TypeError :cannot call method 'remove' of undefined can you please help me figure out these 2 doubts in my code , btw SO member cymen's code works like a charm only my tailored code (above) is giving me errors. SO member cymen's code : JS Fiddle for his code Thank you

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• Dont understand the concept of extends in URL.openConnection() in JAVA

  - by user1722361

  Hi I am trying to learn JAVA deeply and so I am digging into the JDK source code in the following lines: URL url = new URL("http://www.google.com"); URLConnection tmpConn = url.openConnection(); I attached the source code and set the breakpoint at the second line and stepped into the code. I can see the code flow is: URL.openConnection() - sun.net.www.protocol.http.Handler.openConnection() I have two questions about this First In URL.openConnection() the code is: public URLConnection openConnection() throws java.io.IOException { return handler.openConnection(this); } handler is an object of URLStreamHandler, define as blow transient URLStreamHandler handler; But URLStreamHandler is a abstract class and method openConnection() is not implement in it so when handler calls this method, it should go to find a subclass who implement this method, right? But there are a lot classes who implement this methods in sun.net.www.protocol (like http.Hanlder, ftp.Handler ) How should the code know which "openConnection" method it should call? In this example, this handler.openConnection() will go into http.Handler and it is correct. (if I set the url as ftp://www.google.com, it will go into ftp.Handler) I cannot understand the mechanism. second. I have attached the source code so I can step into the JDK and see the variables but for many classes like sun.net.www.protocol.http.Handler, there are not source code in src.zip. I googled this class and there is source code online I can get but why they did not put it (and many other classes) in the src.zip? Where can I find a comprehensive version of source code? Thanks!

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• Plus besoin de failles pour exploiter les PDF malicieux, un chercheur publie un "Proof of Concept" q

  Plus besoin de failles pour exploiter les PDF malicieux Un chercheur en sécurité publie un "Proof of Concept" qu'il a communiqué aux éditeurs Didier Stevens est un chercheur en sécurité qui vient de sérieusement ébranler le format PDF. Il a en effet publié un "Proof of Concept" (une démonstration qui, volontairement, ne va pas jusqu'au bout) - ou PoC - qui permet de lancer l'exécution d'un code via une ligne de commande dans un document PDF. Avec cette méthode, Didier Stevens arrive par exemple à lancer et à faire tourner une calculatrice. Le PoC présenté sur son blog a été réalisé avec Adobe Reader 9.3.1 sur Windows XP SP3 et Windows 7. Mais il fonctio...

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• What would you call the concept of CofeeScript or Sass to be?

  - by MaG3Stican

  There is this rising trend with web development of making new pseudo languages to extend the functionality of JavaScript, CSS and HTML given that those are static and their metamorphosis or evolution is painfully slow due to the variety of browser providers. So I am currently having a concept dilema on how to categorize them for a book I was made to write by my employer as no one seems to have a name for these pseudo languages. A tiny list of them : JavaScript: LiveScript, Metalua, Uberscript, EmberScript. HTML: Razor, Java Scriptlets. CSS : LESS, Sass. I believe the concept of these pseudo languages and a language or an extension of a language is quite different. First these languages do not extend any functionality currently existing on HTML or CSS or JavaScript, they simply work around it. And also they do not "compile" to an intermediate language, they are merely 1-1 translated to something that only then can be compiled. What would you call them?

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• What trivial real-life example do you use to explain programming to total non-programmers?

  - by anon

  Programmers seem to live in a world of their own (as this site indicates), with their own vibrant culture - and their own premises and vocabulary. Once we've been in the field for a bit, we take a lot of things for granted. But I'm often faced with the question "What do you do?" Or "What is programming?" I generally try to answer this with a small, often trivial, real-world example of how programming is prevalent in our everyday lives and keeps things running. The example I use most often is an elevator - someone has to program the logic of that... And I've seen elevators that are "smart" and ones that are quite backwards and foolish. (And you can easily understand if/decision and looping from that... incorporates a lot of important programming concepts in a very small example.) I've sometimes heard people use traffic lights as an example. What example do you / would you use to explain the concept of programming to someone completely clueless?

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• Valid Email Addresses - XSS and SQL Injection

  - by PAAMAYIM_NEKUDOTAYIM

  Since there are so many valid characters for email addresses, are there any valid email addresses that can in themselves be XSS attacks or SQL injections? I couldn't find any information on this on the web. The local-part of the e-mail address may use any of these ASCII characters: Uppercase and lowercase English letters (a–z, A–Z) Digits 0 to 9 Characters ! # $ % & ' * + - / = ? ^ _ ` { | } ~ Character . (dot, period, full stop) provided that it is not the last character, and provided also that it does not appear two or more times consecutively (e.g. [email protected]). http://en.wikipedia.org/wiki/E-mail_address#RFC_specification I'm not asking how to prevent these attacks (I'm already using parametrized queries and HTML purifier), this is more a proof-of-concept. The first thing that came to mind was 'OR [email protected], except that spaces are not allowed. Do all SQL injections require spaces?

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• Is ther any DLL or DLL like concept in Android?

  - by Prashant

  Hello, We know that we can use a concept "Java Package" but I just wanted to know that whether Android has provided a DLL or DLL like concept where we can write a most of the functionality. Or can we use Activity for serving a purpose of DLL. Can any one tell me is there any concept like DLL on Android OS? Can we develop a DLL for better modularization and other benefits on Android? Thanks and Regards, Prashant.

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• Where does this concept of "favor composition over inheritance" come from?

  - by Mason Wheeler

  In the last few months, the mantra "favor composition over inheritance" seems to have sprung up out of nowhere and become almost some sort of meme within the programming community. And every time I see it, I'm a little bit mystified. It's like someone said "favor drills over hammers." In my experience, composition and inheritance are two different tools with different use cases, and treating them as if they were interchangeable and one was inherently superior to the other makes no sense. Also, I never see a real explanation for why inheritance is bad and composition is good, which just makes me more suspicious. Is it supposed to just be accepted on faith? Liskov substitution and polymorphism have well-known, clear-cut benefits, and IMO comprise the entire point of using object-oriented programming, and no one ever explains why they should be discarded in favor of composition. Does anyone know where this concept comes from, and what the rationale behind it is?

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• Does semi-normalization exist as a concept? Is it "normalized"?

  - by Gracchus

  If you don't mind, a tldr on my experience: My experience tldr I have an application that's heavily dependent upon uncertainty, a bane to database design. I tried to normalize it as best as I could according to the capabilities of my database of choice, but a "simple" query took 50ms to read. Nosql appeals to me, but I can't trust myself with it, and besides, normalization has cut down my debugging time immensely over and over. Instead of 100% normalization, I made semi-redundant 1:1 tables with very wide primary keys and equivalent foreign keys. Read times dropped to a few ms, and write times barely degraded. The semi-normalized point Given this reality, that anyone who's tried to rely upon views of fully normalized data is aware of, is this concept codified? Is it as simple as having wide unique and foreign keys, or are there any hidden secrets to this technique? Or is uncertainty merely a special case that has extremely limited application and can be left on the ash heap?

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• What would you think of a job based on mostly doing the proof of concept?

  - by davsan

  I'm working as a developer in a small software company whose main job is interfacing between separate applications, like between a telephony system and an environment control system, between IP TVs and hospitality systems, etc...And it seems like I am the candidate for a new job title in the company, as the person who does the proof of concept of a new interfacing project and does some R&D for prototyping. What do you think the pros and cons of such a job would be, considering mainly the individual progress/regress of a person as a software engineer? And what aspects would you consider essential in a person to put him/her in such a job position?

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• What is the concept behind writing a cancel operation in c++?

  - by ToMan

  I'm attempting to write a cancel operation for a software download application. This application will first transfer the software to the device and then install the software on it. (These are givens I'm not allowed to change). What should the cancel operation do? When a user presses 'cancel', the application should stop transferring/installing the software immediately. Question: Since I've never written a "cancel" function, I'm wondering what are the types of things to consider when writing the code, and what are the common bugs I should expect and how to deal with them? Couldn't find anything in google so if you have some links that would be good reads I'd really appreciate it since I'm not looking for answers I'm just looking for guidelines/macro/concept help

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• What do you call the concept of dynamic data definition?

  - by DJTripleThreat

  Maybe this is simpler and more straightforward then what I'm thinking but I can't seem to find this concept on google anywhere. The concept is this: You have a table in a database and the table has a specified number of columns. However, it has been asked of me by previous clients that there also be a set of dynamic user defined columns that can be added on the fly. What is this concept called and is it considered a design pattern?

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• Recursion Vs Loops

  - by sachin

  I am trying to do work with examples on Trees as given here: http://cslibrary.stanford.edu/110/BinaryTrees.html These examples all solve problems via recursion, I wonder if we can provide a iterative solution for each one of them, meaning, can we always be sure that a problem which can be solved by recursion will also have a iterative solution, in general. If not, what example can we give to show a problem which can be solved only by recursion/Iteration? --

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• Programming languages & proof of concepts

  - by Mike

  There are plenty of programming languages out there, as you all may know. I am primarily looking for a list of programming languages WITH some very neat proof of concepts. I would really like to learn a new language, but whenever I dive into something new and popular, it isn't what I expected. Any tutorial out there will give you code, small examples, but won't show you the true power of the language. I am looking for examples that run entirely on the language that it is exemplifying. For example, If I said C#, I could possibly show you a complete C# app with backend queries, reports, tables, all with a nice interface. It would be completely reliant on the language that is provided, so no supporting languages. I understand that most languages are integrated with other languages in order to provide a richer application. Any links, charts, websites that may reflect this request is appreciated.

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• jQuery's draggable grid

  - by Art

  It looks like that the 'grid' option in the constructor of Draggable is relatively bound to the original coordinates of the element being dragged - so simply put, if you have three draggable divs with their top set respectively to 100, 200, 254 pixels relative to their parent: <div class="parent-div" style="position: relative;"> <div id="div1" class="draggable" style="top: 100px; position: absolute;"></div> <div id="div2" class="draggable" style="top: 200px; position: absolute;"></div> <div id="div3" class="draggable" style="top: 254px; position: absolute;"></div> </div> Adn all of them are getting enabled for dragging with 'grid' set to [1, 100]: draggables = $('.draggable'); $.each(draggables, function(index, elem) { $(elem).draggable({ containment: $('#parent-div'), opacity: 0.7, revert: 'invalid', revertDuration: 300, grid: [1, 100], refreshPositions: true }); }); Problem here is that as soon as you drag div3, say, down, it's top is increased by 100, moving it to 354px instead of being increased by just mere 46px (254 + 46 = 300), which would get it to the next stop in the grid - 300px, if we are looking at the parent-div as a point of reference and "grid holder". I had a look at the draggable sources and it seem to be an in-built flaw - they just do all the calculations relative to the original position of the draggable element. I would like to avoid monkey-patching the code of draggable library and what I am really looking for here is the way how to make the Draggable calculate the grid positions relative to containing parent. However if monkey-patching is unavoidable, I guess I'll have to live with it. Thanks!

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• Security question

  - by Syom

  in my cms i have index.php, where client must enter username and password. if they are correct, he'll moove to admin.php, where the cms is. but now hacker can enter to cms/admin.php, so my security now is awful. i know, that i can use $_SESSION variable. index.php - i can give some value to $_SESSION['success']: $_SESSION['success'] = TRUE, and in admin.php just verify it admin.php if($_SESSION['success'] == TRUE) { my script here... } else header("Location: index.php"); but i want to rich this effect without SESSION. could you give me an idea, how can i do it? thanks

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• Macros in C.... please give the solution

  - by Jungle_hacker

  suppose i declared a macro name anything, xyz() and now i am creating another macro xyz1() and referencing the 1st macro i.e xyz() in 2nd. finally i'll create another macro xyz2() and referencing 2nd macro in 3rd... now my question is is this correct(its executing without any problem)..? and macro xyz() is defined twice.... why its not giving error ? what is the solution..?

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• Learning a new concept - write from scratch or use frameworks?

  - by Stu

  I have recently been trying to learn about MVVM and all of the associated concepts such as repositories, mediators, data access. I made a decision that I would not use any frameworks for this so that I could gain a better understanding of how everything worked. I’m beginning to wonder if that was the best idea because I have hit some problems which I am not able to solve, even with the help of Stack Overflow! Writing from scratch I still feel that you have a much better understanding of something when you have been in the guts of it than if you were at a higher level. The other side of that coin is that you are in the guts of something that you don't fully understand which will lead to bad design decisions. This then makes it hard to get help because you will create unusual scenarios which are less likely to occur when you working within the confines of a framework. I have found that there are plenty of tutorials on the basics of a concept but very few that take you all the way from novice to expert. Maybe I should be looking at a book for this? Using frameworks The biggest motivation for me to use frameworks is that they are much more likely to be used in the workplace than a custom rolled solution. This can be quite a benefit when starting a new job if it's one less thing you have to learn. I feel that there is much better support for a framework than a custom solution which makes sense; many more people are using the framework than the solution that you created. The level of help is much wider as well, from basic questions to really specific, detailed questions. I would be interested to hear other people's views on this. When you are learning something new, should you/do you use frameworks or not? Why? If it's a combination of both, when do you stop one and move on to the other?

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• What arguments can I use to "sell" the BDD concept to a team reluctant to adopt it?

  - by S.Robins

  I am a bit of a vocal proponent of the BDD methodology. I've been applying BDD for a couple of years now, and have adopted StoryQ as my framework of choice when developing DotNet applications. Even though I have been unit testing for many years, and had previously shifted to a test-first approach, I've found that I get much more value out of using a BDD framework, because my tests capture the intent of the requirements in relatively clear English within my code, and because my tests can execute multiple assertions without ending the test halfway through - meaning I can see which specific assertions pass/fail at a glance without debugging to prove it. This has really been the tip of the iceberg for me, as I've also noticed that I am able to debug both test and implementation code in a more targeted manner, with the result that my productivity has grown significantly, and that I can more easily determine where a failure occurs if a problem happens to make it all the way to the integration build due to the output that makes its way into the build logs. Further, the StoryQ api has a lovely fluent syntax that is easy to learn and which can be applied in an extraordinary number of ways, requiring no external dependencies in order to use it. So with all of these benefits, you would think it an easy to introduce the concept to the rest of the team. Unfortunately, the other team members are reluctant to even look at StoryQ to evaluate it properly (let alone entertain the idea of applying BDD), and have convinced each other to try and remove a number of StoryQ elements from our own core testing framework, even though they originally supported the use of StoryQ, and that it doesn't impact on any other part of our testing system. Doing so would end up increasing my workload significantly overall and really goes against the grain, as I am convinced through practical experience that it is a better way to work in a test-first manner in our particular working environment, and can only lead to greater improvements in the quality of our software, given I've found it easier to stick with test first using BDD. So the question really comes down to the following: What arguments can I use to really drive the point home that it would be better to use StoryQ, or at the very least apply the BDD methodology? Can you point me to any anecdotal evidence that I can use to support my argument to adopt BDD as our standard method of choice? What counter arguments can you think of that could suggest that my wish to convert the team efforts to BDD might be in error? Yes, I'm happy to be proven wrong provided the argument is a sound one. NOTE: I am not advocating that we rewrite our tests in their entirety, but rather to simply start working in a different manner for all future testing work.

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• Name of the concept of designing an interface to allow expert users to become more efficient?

  - by Grundlefleck

  I'm searching for sources and further information on a particular concept in user experience design. It's not a particularly complicated concept, just that when designing user interfaces, you should both make it intuitive and simple for new users, but also provide way for users to become more efficient as they become more familiar with the application. An example could be including a prominent button for a common action for new users, but also providing a keyboard shortcut / mnemonic for expert users. However, that's just an example, another example could be providing full functionality through a GUI, but allow expert users to script the same actions. The point is it's more difficult to learn, but it makes them more efficient. I'm pretty sure there's a name for that which I can't recall, and I'm having trouble searching for sources and references on it. Name of the concept of designing an interface to allow expert users to become more efficient?

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• OOP concept: is it possible to update the class of an instantiated object?

  - by Federico

  I am trying to write a simple program that should allow a user to save and display sets of heterogeneous, but somehow related data. For clarity sake, I will use a representative example of vehicles. The program flow is like this: The program creates a Garage object, which is basically a class that can contain a list of vehicles objects Then the users creates Vehicles objects, these Vehicles each have a property, lets say License Plate Nr. Once created, the Vehicle object get added to a list within the Garage object --Later on--, the user can specify that a given Vehicle object is in fact a Car object or a Truck object (thus giving access to some specific attributes such as Number of seats for the Car, or Cargo weight for the truck) At first sight, this might look like an OOP textbook question involving a base class and inheritance, but the problem is more subtle because at the object creation time (and until the user decides to give more info), the computer doesn't know the exact Vehicle type. Hence my question: how would you proceed to implement this program flow? Is OOP the way to go? Just to give an initial answer, here is what I've came up until now. There is only one Vehicle class and the various properties/values are handled by the main program (not the class) through a dictionary. However, I'm pretty sure that there must be a more elegant solution (I'm developing using VB.net): Public Class Garage Public GarageAdress As String Private _ListGarageVehicles As New List(Of Vehicles) Public Sub AddVehicle(Vehicle As Vehicles) _ListGarageVehicles.Add(Vehicle) End Sub End Class Public Class Vehicles Public LicensePlateNumber As String Public Enum VehicleTypes Generic = 0 Car = 1 Truck = 2 End Enum Public VehicleType As VehicleTypes Public DictVehicleProperties As New Dictionary(Of String, String) End Class NOTE that in the example above the public/private modifiers do not necessarily reflect the original code

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• What is your most unusual javascript concept you've ever seen ?

  - by Cybrix

  Hi, I've learned javascript at school but since I'm working with it and study about it every day, I've found very particular aspect of javascript that I didn't know about. Which at first, was very hard to understand for me and finally, I found it very usefull and easy to implement. And in the final, it gives to my code some kind of "beauty". An example I've once seen: function getter( input ) { result = { foo1 : 'bar1', foo2 : 'bar2', foo3 : 'bar3' }[input] || input || "default"; return result; } Do you guys have other examples of particular use you make of Javascript ? Thank you PS: I use the term particular use because it might be unusual for any Javascript beginner. I believe this question is most likely to belong to the community wiki.

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• Is excessive indirection and/or redundant encapsulation a recognized concept?

  - by Omega

  I'm curious if there's a series of tendencies or anti-patterns when programming whereby a developer will always locally re-wrap external dependencies when consuming them. A slightly less vague example might be say when consuming an implementation of an interface or abstract, and mapping every touch-point locally before interacting with them. Like an overcomplicated take on composition. Given my example, would the interface not be reliable enough and any change to it never be surmountable any any level of indirection? Is this a good or a bad practice? Can it ever go too far? Does it have a proper name?

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