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• How to check any undocumented methods provided by apple?

  - by Mahbubur R Aaman

  The following tools is provided by Apple dlopen dlsym objc_getClass sel_registerName objc_msgSend Those are listing Objective-C selectors, or strings. Objective-C selectors are stored in a special region of the binary, and therefore Apple could extract the content from there, and check if you've used some undocumented Objective-C methods. How to utilize these tools to find undocumented Objective-C methods? EDIT: Recently, one of my App rejected due to using one undocumented methods. -[UIDevice setOrientation] Since, selectors are independent from the class you're messaging, even if my custom class defines -setOrientation: irrelevant to UIDevice, there will be a possbility of being rejected.

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• How do I fix a "E: The method driver /usr/lib/apt/methods/http could not be found." error?

  - by Abe

  I tried updating my packages from the terminal and this is what I got: $ sudo apt-get update E: The method driver /usr/lib/apt/methods/http could not be found. E: The method driver /usr/lib/apt/methods/http could not be found. E: The method driver /usr/lib/apt/methods/http could not be found. E: The method driver /usr/lib/apt/methods/http could not be found. E: The method driver /usr/lib/apt/methods/http could not be found. What does this mean? I'm using the United States mirror an I've tried using the main server for the mirror and I keep getting the same result is this because there are no updates?

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• Public versus private inheritance when some of the parent's methods need to be exposed?

  - by Vorac

  Public inheritance means that all fields from the base class retain their declared visibility, while private means that they are forced to 'private' within the derived class's scope. What should be done if some of the parent's members (say, methods) need to be publicly exposed? I can think of two solution. Public inheritance somewhat breaks encapsulation. Furthermore, when you need to find out where is the method foo() defined, one needs to look at a chain of base classes. Private inheritance solves these problems, but introduces burden to write wrappers (more text). Which might be a good thing in the line of verbosity, but makes changes of interfaces incredibly cumbersome. What considerations am I missing? What constraints on the type of project are important? How to choose between the two (I am not even mentioning 'protected')? Note that I am targeting non-virtual methods. There isn't such a discussion for virtual methods (or is there).

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• Is there such a thing as having too many private functions/methods?

  - by shovonr

  I understand the importance of well documented code. But I also understand the importance of self-documenting code. The easier it is to visually read a particular function, the faster we can move on during software maintenance. With that said, I like to separate big functions into other smaller ones. But I do so to a point where a class can have upwards of five of them just to serve one public method. Now multiply five private methods by five public ones, and you get around twenty-five hidden methods that are probably going to be called only once by those public ones. Sure, it's now easier to read those public methods, but I can't help but think that having too many functions is bad practice.

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• Using static methods in objects PHP - is it advantage?

  - by RePRO

  I was reading some articles and discussions on the use of static methods on objects and it struck me how much the views differ. Someone say that using static methods is an advantage. Someone says that use is a big mistake. I wonder how is it? My question is when to use static methods and when not? I would like to hear answers from experts in this field (PHP OOP). This is because I know how it really is. The following code should be analogous. Just call the static method is simpler (my opinion): <?php class A { public function write($a) { echo $a; } } class B { public static function write($a) { echo $a; } } $a = new A; $a->write(5); // 5 B::write(5); // 5 ?> Thank you.

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• Generic wrapper for System.Web.Caching.Cache functions

  - by David Neale

  I've created a generic wrapper for using the Cache object: public class Cache<T> where T : class { public Cache Cache {get;set;} public CachedKeys Key {get;set;} public Cache(Cache cache, CachedKeys key){ Cache = cache; Key = key; } public void AddToCache(T obj){ Cache.Add(Key.ToString(), obj, null, DateTime.Now.AddMinutes(5), System.Web.Caching.Cache.NoSlidingExpiration, System.Web.Caching.CacheItemPriority.Normal, null); } public bool TryGetFromCache(out T cachedData) { cachedData = Cache[Key.ToString()] as T; return cachedData != null; } public void RemoveFromCache() { Cache.Remove(Key.ToString()); } } The CachedKeys enumeration is just a list of keys that can be used to cache data. The trouble is, to call it is quite convuluted: var cache = new Cache<MyObject>(Page.Cache, CachedKeys.MyKey); MyObject myObject = null; if(!cache.TryGetFromCache(out myObject)){ //get data... cache.AddToCache(data); //add to cache return data; } return myObject; I only store one instance of each of my objects in the cache. Therefore, is there any way that I can create an extension method that accepts the type of object to Cache and uses (via Reflection) its Name as the cache key? public static Cache<T> GetCache(this Cache cache, Type cacheType){ Cache<cacheType> Cache = new Cache<cacheType>(cache, cacheType.Name); } Of course, there's two errors here: Extension methods must be defined in a non-generic static class The type or namespace name 'cacheType' could not be found This is clearly not the right approach but I thought I'd show my working. Could somebody guide me in the right direction?

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• Scaling Literate Programming?

  - by Tetha

  Greetings. I have been looking at Literate Programming a bit now, and I do like the idea behind it: you basically write a little paper about your code and write down as much of the design decisions, the code probably surrounding the module, the inner workins of the module, assumptions and conclusions resulting from the design decisions, potential extension, all this can be written down in a nice way using tex. Granted, the first point: it is documentation. It must be kept up-to-date, but that should not be that bad, because your change should have a justification and you can write that down. However, how does Literate Programming Scale to a larger degree? Overall, Literate Programming is still just text. Very human readable text, of course, but still text, and thus, it is hard to follow large systems. For example, I reworked large parts of my compiler to use and some magic to chain compile steps together, because some "x.register_follower(y); y.register_follower(z); y.register_follower(a);..." got really unwieldy, and changing that to x y z a made it a bit better, even though this is at its breaking point, too. So, how does Literate Programming scale to larger systems? Does anyone try to do that? My thought would be to use LP to specify components that communicate with each other using event streams and chain all of these together using a subset of graphviz. This would be a fairly natural extension to LP, as you can extract a documentation -- a dataflow diagram -- from the net and also generate code from it really well. What do you think of it? -- Tetha.

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• Accessing XUL anonymous content using C++

  - by Vaibhav Gade

  Hi All, I am writing Firefox extension using C++. I am trying to access XUL:tabox element in "TabOpen" event handler, but I am unable access any XUL element. I am putting here pseudocode of my extension for reference: HandleEvent() { if (event type is TabOpen) { nsCOMPtr<nsIDOMNode> OriginalNode = do_QueryInterface(event->GetTarget); nsCOMPtr<nsIDOMNodeList> childlist; // // Note here that I got OriginalNode's local name as "tabbrowser" // OriginalNode->GetChildNodes(getter_AddRefs(childlist)); PRUint32 len; childlist->GetLength(&len); // Return 1; consider only "popup" child element. nsString localName; nsCOMPtr<nsIDOMNode> node1; childlist->Item(0, getter_AddRefs(node1)); node1->GetLocalName(localName); // Returns "popup" as the local name. } } By traversing the DOM tree through DOM Inspector, I came to know that XUL elements are anonymous content. How do I access these XUL elements? Very Thanks in advance, Vaibhav.

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• LibPNG + Boost::GIL: png_infopp_NULL not found

  - by Viet

  Hi, I always get this error when trying to compile my file with Boost::GIL PNG IO support: (I'm running Mac OS X Leopard and Boost 1.42, LibPNG 1.4) /usr/local/include/boost/gil/extension/io/png_io_private.hpp: In member function 'void boost::gil::detail::png_reader::init()': /usr/local/include/boost/gil/extension/io/png_io_private.hpp:155: error: 'png_infopp_NULL' was not declared in this scope /usr/local/include/boost/gil/extension/io/png_io_private.hpp:160: error: 'png_infopp_NULL' was not declared in this scope /usr/local/include/boost/gil/extension/io/png_io_private.hpp: In destructor 'boost::gil::detail::png_reader::~png_reader()': /usr/local/include/boost/gil/extension/io/png_io_private.hpp:174: error: 'png_infopp_NULL' was not declared in this scope /usr/local/include/boost/gil/extension/io/png_io_private.hpp: In member function 'void boost::gil::detail::png_reader::apply(const View&)': /usr/local/include/boost/gil/extension/io/png_io_private.hpp:186: error: 'int_p_NULL' was not declared in this scope /usr/local/include/boost/gil/extension/io/png_io_private.hpp: In member function 'void boost::gil::detail::png_reader_color_convert<CC>::apply(const View&)': /usr/local/include/boost/gil/extension/io/png_io_private.hpp:228: error: 'int_p_NULL' was not declared in this scope /usr/local/include/boost/gil/extension/io/png_io_private.hpp: In member function 'void boost::gil::detail::png_writer::init()': /usr/local/include/boost/gil/extension/io/png_io_private.hpp:317: error: 'png_infopp_NULL' was not declared in this scope

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• How do I Extend Blogengine.Net to collect statistics of visitors?

  - by Stefan

  I love BlogEngine. But from what I can se it does not collect the standard information about the visitors I would like to see (referrer, browser-type and so on). When I log in as Admin I have a menu item named "Referrer". I can choose a weekday and then I'll be presented with 1 or 2 rows with "google.com 4 hits, "itmaskinen.se 6 hits" and so on, But that's not what I want to se, I want to se where my visitors come from, country, IP if possible, how many visitors and so on. If someone of you are familiar with Blogengine.Net and can point me in the right direction to where I would put my own log-code or if you know any visitor-statistic-extension that can do it for me, I would be really happy to know. I prefer an extension, because if I make changes myself to BlogEngine it may break later updates I install. Blogengine.Net is a blog software made in .Net found here: http://www.dotnetblogengine.net/ And yes, I prefer to take this question here rather then in the Blogengine.Net forum, you know why. ;) (Anyone, feel free to edit my (bad) english in this post and after that delete this sentence)

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• Can Content script set value of a text box within HTML frame? using Google Chrome extensions..

  - by devdreamers

  Hi all, I was working on a very simple extension, where on clicking extension icon, a webpage is opened in a new tab, the webpage has HTML frames, within which lies a textbox. I want to set a value for the same. The webpage which opens has: <HTML> <FRAMESET rows="15%, *" border="0"> <FRAME src="./files/abc.htm" id="abc_frame" name="abc_frame" onload="abcLoad()" scrolling="NO"> </FRAMESET> </HTML> and abc.htm has: <div align="center" valign="bottom" style="font-size: 1em;"> <form onSubmit="javascript:navigate(this);return false;"> <label for="loc">Loc</label>: <input type="text" size="50" id="loc" value="http://google.com"/> <input name="go" type="submit" value="Go" id="loc_go" onclick='navigate(this); return false;'/> </form> </div> how can I replace current textbox value with, say http://yahoo.com ? I guess, Content Script in Chrome extensions is required, but not sure, how/what should be it's code/content. Please guide/help. Thanks a lot. Appreciate it.

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• Chrome.tabs.getSelected() doesn't work. What am I doing wrong ?

  - by warv3n

  Hi there ! I'm building my first GC extension, and I am having a problem using this function. I would like to get the url of the current tab, and to do so (after some google research, of course), I use the chrome.tabs.getSelected() function. Here it is in my code : ... socket.onopen = function(msg){ log("Welcome - status " + this.readyState); chrome.tabs.getSelected(null, function(tab){ sendUrl(tab.url); }); }; function sendUrl(tabUrl) { socket.send("#URL#"+ tabUrl); } The socket.open is a listener for the Websocket API I use in my extension. The log function print the status of the socket (1, which means it's OPEN or connected and ready to communicate, according to the Websocket API), but the chrome.tabs.getSelected() function do not seems to work, as the server do not receive anything (the socket is not the problem here, I tried to send a test message with socket.send() instead of chrome.tabs.getSelected() and the server received it). I put the permissions: ["tabs"] into the manifest.json so I can use this function. So I don't know what I am doing wrong here ? I also tried to put chrome.tab.getSelected() elsewhere in the code, but it is still not working. Any help is welcome :)

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• How to use a variable in a function expression which is injected in a page?

  - by anonymous

  I'm trying to inject a function into a webpage via Chrome extension content script by: function inject(code) { var actualCode = '(' + code + ')();'; var script = document.createElement('script'); script.textContent = actualCode; (document.head||document.documentElement).appendChild(script); script.parentNode.removeChild(script); } var myObj = person; // myObj/person is passed in from elsewhere var fn = function() { alert(myObj.name); }; inject(fn); // myObj undefined My issue is, since fn is a function expression, I can't pass in myObj.personName. So my question is, how can I construct a function expression that includes a variable? Do I do some sort of string concatenation instead? I also tried to pass the object to the function, as follows: function inject(code, myObj) { var actualCode = '(' + code + ')(' + myObj +');'; ... But this did not work, and caused a "Uncaught SyntaxError: Unexpected identifier" error. Related: Building a Chrome Extension - Inject code in a page using a Content script

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• How to create a dynamic Linq Join extension method

  - by Royd Brayshay

  There was a library of dynamic Linq extensions methods released as a sample with VS2008. I'd like to extend it with a Join method. The code below fails with a parameter miss match exception at run time. Can anyone find the problem? public static IQueryable Join(this IQueryable outer, IEnumerable inner, string outerSelector, string innerSelector, string resultsSelector, params object[] values) { if (inner == null) throw new ArgumentNullException("inner"); if (outerSelector == null) throw new ArgumentNullException("outerSelector"); if (innerSelector == null) throw new ArgumentNullException("innerSelector"); if (resultsSelector == null) throw new ArgumentNullException("resultsSelctor"); LambdaExpression outerSelectorLambda = DynamicExpression.ParseLambda(outer.ElementType, null, outerSelector, values); LambdaExpression innerSelectorLambda = DynamicExpression.ParseLambda(inner.AsQueryable().ElementType, null, innerSelector, values); ParameterExpression[] parameters = new ParameterExpression[] { Expression.Parameter(outer.ElementType, "outer"), Expression.Parameter(inner.AsQueryable().ElementType, "inner") }; LambdaExpression resultsSelectorLambda = DynamicExpression.ParseLambda(parameters, null, resultsSelector, values); return outer.Provider.CreateQuery( Expression.Call( typeof(Queryable), "Join", new Type[] { outer.ElementType, inner.AsQueryable().ElementType, outerSelectorLambda.Body.Type, innerSelectorLambda.Body.Type, resultsSelectorLambda.Body.Type }, outer.Expression, inner.AsQueryable().Expression, Expression.Quote(outerSelectorLambda), Expression.Quote(innerSelectorLambda), Expression.Quote(resultsSelectorLambda))); } I've now fixed it myself, here's the answer. Please vote it up or add a better one.

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• DataContractSerializer does not properly deserialize, values for methods in object are missing

  - by sachin

  My SomeClass [Serializable] [DataContract(Namespace = "")] public class SomeClass { [DataMember] public string FirstName { get; set; } [DataMember] public string LastName { get; set; } [DataMember] private IDictionary<long, string> customValues; public IDictionary<long, string> CustomValues { get { return customValues; } set { customValues = value; } } } My XML File: <?xml version="1.0" encoding="UTF-8"?> <SomeClass> <FirstName>John</FirstName> <LastName>Smith</LastName> <CustomValues> <Value1>One</Value1> <Value2>Two</Value2> </CustomValues > </SomeClass> But my problem is for the class, i am only getting some of the data for my methods when i deserialize. var xmlRoot = XElement.Load(new StreamReader( filterContext.HttpContext.Request.InputStream, filterContext.HttpContext.Request.ContentEncoding)); XmlDictionaryReader reader = XmlDictionaryReader.CreateDictionaryReader(xmlRoot.CreateReader()); DataContractSerializer ser = new DataContractSerializer(typeof(SomeClass)); //Deserialize the data and read it from the instance. SomeClass someClass = (SomeClass)ser.ReadObject(reader, true); So when I check "someClass", FirstName will have the value john, But the LastName will be null. Mystery is how can i get some of the data and not all of the data for the class. So DataContractSerializer is not pulling up all the data from xml when deserializing. Am i doing something wrong. Any help is appreciated. Thanks in advance. Let me know if anyone has the same problem or any one has solution

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• Constant NSDictionary/NSArray for class methods.

  - by Jeff B

  I am trying to code a global lookup table of sorts. I have game data that is stored in character/string format in a plist, but which needs to be in integer/id format when it is loaded. For instance, in the level data file, a "p" means player. In the game code a player is represented as the integer 1. This let's me do some bitwise operations, etc. I am simplifying greatly here, but trying to get the point across. Also, there is a conversion to coordinates for the sprite on a sprite sheet. Right now this string-integer, integer-string, integer-coordinate, etc. conversion is taking place in several places in code using a case statement. This stinks, of course, and I would rather do it with a dictionary lookup. I created a class called levelInfo, and want to define the dictionary for this conversion, and then class methods to call when I need to do a conversion, or otherwise deal with level data. NSString *levelObjects = @"empty,player,object,thing,doohickey"; int levelIDs[] = [0,1,2,4,8]; // etc etc @implementation LevelInfo +(int) crateIDfromChar: (char) crateChar { int idx = [[crateTypes componentsSeparatedByString:@","] indexOfObject: crateChar]; return levelIDs[idx]; } +(NSString *) crateStringFromID: (int) crateID { return [[crateTypes componentsSeparatedByString:@","] objectAtIndex: crateID]; } @end Is there a better way to do this? It feels wrong to basically build these temporary arrays, or dictionaries, or whatever for each call to do this translation. And I don't know of a way to declare a constant NSArray or NSDictionary. Please, tell me a better way....

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• Twitter-OAuth update_profile_*_image methods problem [EpiTwitter]

  - by KPL

  People, I have been struggling over the two methods - Update Profile Image and Update Background Image I am using EpiTwitter library. I am uploading GIFs, Twitter returns the expected result for update_profile_background_image but returns 401 for update_profile_image , but the image is not changed. Here are the headers catched from $apiObj-headers in my case while using the update_profile_background_image Array ( [Date] = Sat, 24 Apr 2010 17:51:36 GMT [Server] = hi [Status] = 200 OK [X-Transaction] = 1272131495-55190-23911 [ETag] = b6a421c01936f3547802ae6b59ee7ef3" [Last-Modified] = Sat, 24 Apr 2010 17:51:36 GMT [X-Runtime] = 0.13990 [Content-Type] = application/json; charset=utf-8 [Content-Length] = 1272 [Pragma] = no-cache [X-Revision] = DEV [Expires] = Tue, 31 Mar 1981 05:00:00 GMT [Cache-Control] = no-cache, no-store, must-revalidate, pre- check=0, post-check=0 [Set-Cookie] = *REMOVED* [Vary] = Accept-Encoding [Connection] = close ) and for update_profile_image - Array ( [Date] => Sat, 24 Apr 2010 17:57:58 GMT [Server] => hi [Status] => 401 Unauthorized [WWW-Authenticate] => Basic realm="Twitter API" [X-Runtime] => 0.02263 [Content-Type] => text/html; charset=utf-8 [Content-Length] => 152 [Cache-Control] => no-cache, max-age=300 [Set-Cookie] => *REMOVED* [Expires] => Sat, 24 Apr 2010 18:02:58 GMT [Vary] => Accept-Encoding [Connection] => close ) Can somebody help me out?

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• WPF: UnauthorizedAccessException using anonymous methods.

  - by Diego Pacheco Pedemonte

  Here is the thing, I want to create a simply app that copy many files from one site, and move them to another; but using async methods and create a new thread. private void button3_Click(object sender, RoutedEventArgs e) { //progressBar1.Maximum = _FileInfoArray.Count; DispatcherTimer dt1 = new DispatcherTimer(); foreach (FileInfo Fi in _FileInfoArray) { Thread t = new Thread(new ThreadStart(delegate() { DispatcherOperation _dispOp = progressBar1.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new Action(delegate() { File.Copy(txtdestino.Text, Fi.FullName, true); //progressBar1.Value = n; //txtstatus.Content = ("Copiados " + n.ToString() + " archivos"); //Thread.Sleep(100); } )); _dispOp.Completed += new EventHandler(_dispOp_Completed); } )); t.Start(); } } UnauthorizedAccessException is throw! It says that I can't access to txtdestino content. Some clues? -------------------------------------------------------------------------------Edited This is the version with all the changes, get the same error :( any clues? private void button4_Click(object sender, RoutedEventArgs e) { //First: Build mynames List<string> mynames = new List<string>(); foreach (FileInfo fi in _FileInfoArray) { mynames.Add(fi.FullName); } Thread t = new Thread(new ThreadStart(delegate() { foreach (string fullname in mynames) { DispatcherOperation _dispOp = progressBar1.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new Action(delegate() { string destino = System.IO.Path.Combine(@"C:\", System.IO.Path.GetFileName(fullname)); File.Copy(fullname, destino, true); //Some progressbar changes } )); _dispOp.Completed += new EventHandler(_dispOp_Completed); } } )); t.Start(); } File.Copy(txtdestino.Text, Fi.FullName, true); // here the exception is throw

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• Accessing bean object methods from xhtml in RichFaces

  - by Mark Lewis

  Hello When I use (1) in my xhtml, I get an error as in (2). How can I access the size of an array in my bean? (1) A List of objects of a custom class type, accessed through the following h:outputText in a rich:column in a rich:subTable in a rich:dataTable: <h:outputText value="Info: #{f.filemask.size()}" /> (2) Caused by: com.sun.facelets.tag.TagAttributeException: /nodeConfig.xhtml @190,91 value="Info: #{f.filemask.size()" Error Parsing: Info:  #{f.filemask.size()} at com.sun.facelets.tag.TagAttribute.getValueExpression(TagAttribute.java:259) ... Caused by: org.apache.el.parser.ParseException: Encountered " "(" "( "" at line 1, column 41. Was expecting one of: "}" ... "." ... "[" ... ">" ... "gt" ... "<" ... "lt" ... ">=" ... "ge" ... "<=" ... "le" ... "==" ... "eq" ... "!=" ... "ne" ... "&&" ... "and" ... "||" ... "or" ... "*" ... "+" ... "-" ... "/" ... "div" ... "%" ... "mod" ... Any help greatly appreciated. I cannot seem to find references to using methods like this but this reference reported it working fine

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• Call private methods and private properties from outside a class in PHP

  - by Pablo López Torres

  I want to access private methods and variables from outside the classes in very rare specific cases. I've seen that this is not be possible although introspection is used. The specific case is the next one: I would like to have something like this: class Console { final public static function run() { while (TRUE != FALSE) { echo "\n> "; $command = trim(fgets(STDIN)); switch ($command) { case 'exit': case 'q': case 'quit': echo "OK+\n"; return; default: ob_start(); eval($command); $out = ob_get_contents(); ob_end_clean(); print("Command: $command"); print("Output:\n$out"); break; } } } } This method should be able to be injected in the code like this: Class Demo { private $a; final public function myMethod() { // some code Console::run(); // some other code } final public function myPublicMethod() { return "I can run through eval()"; } private function myPrivateMethod() { return "I cannot run through eval()"; } } (this is just one simplification. the real one goes through a socket, and implement a bunch of more things...) So... If you instantiate the class Demo and you call $demo-myMethod(), you'll get a console: that console can access the first method writing a command like: > $this->myPublicMethod(); But you cannot run successfully the second one: > $this->myPrivateMethod(); Do any of you have any idea, or if there is any library for PHP that allows you to do this? Thanks a lot!

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• Securely erasing a file using simple methods?

  - by Jason

  Hello, I am using C# .NET Framework 2.0. I have a question relating to file shredding. My target operating systems are Windows 7, Windows Vista, and Windows XP. Possibly Windows Server 2003 or 2008 but I'm guessing they should be the same as the first three. My goal is to securely erase a file. I don't believe using File.Delete is secure at all. I read somewhere that the operating system simply marks the raw hard-disk data for deletion when you delete a file - the data is not erased at all. That's why there exists so many working methods to recover supposedly "deleted" files. I also read, that's why it's much more useful to overwrite the file, because then the data on disk actually has to be changed. Is this true? Is this generally what's needed? If so, I believe I can simply write the file full of 1's and 0's a few times. I've read: http://www.codeproject.com/KB/files/NShred.aspx http://blogs.computerworld.com/node/5756 http://blogs.computerworld.com/node/5687 http://stackoverflow.com/questions/4147775/securely-deleting-a-file-in-c-net

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• Synchronizing ASP.NET MVC action methods with ReaderWriterLockSlim

  - by James D

  Any obvious issues/problems/gotchas with synchronizing access (in an ASP.NET MVC blogging engine) to a shared object model (NHibernate, but it could be anything) at the Controller/Action level via ReaderWriterLockSlim? (Assume the object model is very large and expensive to build per-request, so we need to share it among requests.) Here's how a typical "Read Post" action would look. Enter the read lock, do some work, exit the read lock. public ActionResult ReadPost(int id) { // ReaderWriterLockSlim allows multiple concurrent writes; this method // only blocks in the unlikely event that some other client is currently // writing to the model, which would only happen if a comment were being // submitted or a new post were being saved. _lock.EnterReadLock(); try { // Access the model, fetch the post with specificied id // Pseudocode, etc. Post p = TheObjectModel.GetPostByID(id); ActionResult ar = View(p); return ar; } finally { // Under all code paths, we must release the read lock _lock.ExitReadLock(); } } Meanwhile, if a user submits a comment or an author authors a new post, they're going to need write access to the model, which is done roughly like so: [AcceptVerbs(HttpVerbs.Post)] public ActionResult SaveComment(/* some posted data */) { // try/finally omitted for brevity _lock.EnterWriteLock(); // Save the comment to the DB, update the model to include the comment, etc. _lock.ExitWriteLock(); } Of course, this could also be done by tagging those action methods with some sort of "synchronized" attribute... but however you do it, my question is is this a bad idea? ps. ReaderWriterLockSlim is optimized for multiple concurrent reads, and only blocks if the write lock is held. Since writes are so infrequent (1000s or 10,000s or 100,000s of reads for every 1 write), and since they're of such a short duration, the effect is that the model is synchronized , and almost nobody ever locks, and if they do, it's not for very long.

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• Naming convention for non-virtual and abstract methods

  - by eagle

  I frequently find myself creating classes which use this form (A): abstract class Animal { public void Walk() { // TODO: do something before walking // custom logic implemented by each subclass WalkInternal(); // TODO: do something after walking } protected abstract void WalkInternal(); } class Dog : Animal { protected override void WalkInternal() { // TODO: walk with 4 legs } } class Bird : Animal { protected override void WalkInternal() { // TODO: walk with 2 legs } } Rather than this form (B): abstract class Animal { public abstract void Walk(); } class Dog : Animal { public override void Walk() { // TODO: do something before walking // custom logic implemented by each subclass // TODO: walk with 4 legs // TODO: do something after walking } } class Bird : Animal { public override void Walk() { // TODO: do something before walking // custom logic implemented by each subclass // TODO: walk with 2 legs // TODO: do something after walking } } As you can see, the nice thing about form A is that every time you implement a subclass, you don't need to remember to include the initialization and finalization logic. This is much less error prone than form B. What's a standard convention for naming these methods? I like naming the public method Walk since then I can call Dog.Walk() which looks better than something like Dog.WalkExternal(). However, I don't like my solution of adding the suffix "Internal" for the protected method. I'm looking for a more standardized name. Btw, is there a name for this design pattern?

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• Methods for Lazy Initialization with properties

  - by Stuart Pegg

  I'm currently altering a widely used class to move as much of the expensive initialization from the class constructor into Lazy Initialized properties. Below is an example (in c#): Before: public class ClassA { public readonly ClassB B; public void ClassA() { B = new ClassB(); } } After: public class ClassA { private ClassB _b; public ClassB B { get { if (_b == null) { _b = new ClassB(); } return _b; } } } There are a fair few more of these properties in the class I'm altering, and some are not used in certain contexts (hence the Laziness), but if they are used they're likely to be called repeatedly. Unfortunately, the properties are often also used inside the class. This means there is a potential for the private variable (_b) to be used directly by a method without it being initialized. Is there a way to make only the public property (B) available inside the class, or even an alternative method with the same initialized-when-needed? This is reposted from Programmers (not subjective enough apparently): http://programmers.stackexchange.com/questions/34270/best-methods-for-lazy-initialization-with-properties

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• AS3 - Can't access properties or methods of a MC child that has been added in script

  - by Chris

  Hi All - I am still a bit of a beginner at AS3, so bear with me, please. I have created a loop to instantiate tiles on a board. In the following example, "Gametiles" is an array containing objects of class "Tile" which is a class that extends MovieClip. "Game" is a MC that I added to the stage in the flash developing environment. for(var i:uint=0;i < Gametiles.length;i++){ var pulledTile = Gametiles[i]; var tilename:String = "I_Tile_" + pulledTile.grid_y + "_" + pulledTile.grid_x; var createdTile = new InteractiveTile(); pulledTile.addAnims(createdTile); Game.addChildAt(pulledTile, 0); Game.getChildAt(0).name = tilename; } The above code works - but with a tricky problem. If I did something like the following: trace(Game.I_Tile_1_3.x); I get "TypeError: Error #1010: A term is undefined and has no properties." However, I am able to access theses children in the following manner: var testing = Game.getChildByName("I_Tile_1_3") trace(testing.x); This method is a bit cumbersome though. I really don't want to have to create a var and call getChildByName every time I want to interact with these properties or methods. How can I set up these children so that I can access them directly without the extra steps?

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