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• In Java how instance of and type cast(i.e (ClassName)) works on proxy object ?

  - by learner

  Java generates a proxy class for a given interface and provides the instance of the proxy class. But when we type cast the proxy object to our specific Object, how java handles this internally? Is this treated as special scenario? For example I have class 'OriginalClass' and it implements 'OriginalInterface', when I create proxy object by passing 'OriginalInterface' interface java created proxy class 'ProxyClass' using methods in the provided interface and provides object of this class(i.e ProxyClass). If my understanding is correct then can you please answer following queries 1) When I type cast object of ProxyClass to my class OriginalClass this works, but how java is allowing this? Same in case of instace of? 2) As my knowledge java creates a proxy class only with the methods, but what happen when I try to access attributes on this object? 3) Only interface methods are getting implemented in Proxy, but what happens when I try to access a method which not in interface and only mentioned in the class? Thanks, Student

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• Why are my margins still collapsing?

  - by Brandon Dorsey

  My code in this "Fiddle" shows that I have adjacent elements which vertical margins are collapsing on one another. I understand that due to the nature of vertical margins in css, the largest of the two is chosen, In my case the p tag. What I am having trouble with is trying to break the margins by using a 1px border or 1px padding. I've seen it work with other workarounds such as position:absolute or float method. I am not understanding why using 1px border or padding is not working properly to give me 15px of space.

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• How can I use Object Oriented Javascript to interact with HTML Objects

  - by Steve

  I am very new to object orientated javascript, with experience writing gui's in python and java. I am trying to create html tables that I can place in locations throughout a webpage. Each html table would have two css layouts that control if it is selected or not. I can write all of the interaction if I only have one table. It gets confusing when I have multiple tables. I am wondering how to place these tables throughout a blank webpage and then access the tables individually. I think I am having trouble understanding how inheritance and hierarchy works in javascript/html. NOTE: I am not asking how to make a table. I am trying to dynamically create multiple tables and place them throughout a webpage. Then access their css independently and change it (move them to different locations or change the way the look, independently of the other tables).

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• JavaScript inheritance extend function

  - by Zach

  I'm having some trouble understanding the IF clause at the end of this function from Pro JavaScript Design Patterns: function extend(subClass, superClass) { var F = function() {}; F.prototype = superClass.prototype; subClass.prototype = new F(); subClass.prototype.constructor = subClass; subClass.superclass = superClass.prototype; if(superClass.prototype.constructor == Object.prototype.constructor) { superClass.prototype.constructor = superClass; } } The book explains that these lines ensure that the superclass's constructor attribute is correctly set, even if the superclass is the Object class itself. Yet, if I omit those three lines and do the following: function SubClass() {}; extend(SubClass, Object); alert(Object.prototype.constructor == Object); The alert says 'true', which means the superclass's constructor is set correctly even without those last three lines. Under what conditions, then, does this IF statement do something useful? Thanks.

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• Response.Redirect causes System.Threading.ThreadAbortException

  - by RandomBen

  When I use Response.Redirect(...) to redirect my form to a new page I get the error: A first chance exception of type 'System.Threading.ThreadAbortException' occurred in mscorlib.dll An exception of type 'System.Threading.ThreadAbortException' occurred in mscorlib.dll but was not handled in user code My understanding of this is that the error is being caused by the webserver aborting the remainder of the page the response.redirect was called on. I know I can add a second parameter to Response.Redirect that is called endResponse. If I set endResponse to True I still get the error but if I set it to False then I do not. I am pretty sure though that that means the webserver is running the rest of the page I redirected away from. Which would seem to be inefficient to say the least. Is there a better way to do this? Something other than Response.Redirect or is there a way to force the old page to stop loading where I will not get a ThreadAbortException?

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• CruiseControl.NET merge nunit and nant output

  - by JK

  I've just started using ccnet so I'm having trouble understanding why the merging of nant and nunit outputs are not working. I've setup my ccnet.config with typical values as found on google: <merge> <files> <file>D:\ccnet\path1\nant-results.xml</file> <file>D:\ccnet\path2\TestResult.xml</file> </files> </merge> <xmllogger /> Nant and ccnet are half working: if I deliberately put in a code error, then ccnet will say build failed. The same happens if I deliberately put in a failing test, ccnet will say build failed. But the ViewBuildReport.aspx page does not show any of the output from nant or nunit. Obviously I must be missing something, but I don't know what, any ideas? Thanks, JK

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• Learning C++ from AS3

  - by grey

  I'm a decent AS3 programmer. I work in games, and that is my reason for programming. While there is much I can accomplish with Adobe AIR, my understanding at this point is that learning C++ is probably a good direction to take. I would learn a lot of valuable lower level programming if I needed it down the road, and I would have an easier time learning other C oriented languages. I see a lot of information for people looking to learn AS3 who know C++, but not the other way around. Why C++? Cross platform compatibility is important to me, so I'm not particularly interested in C# or Objective-C at this junction. I'm also aware of HaXe, and while I love the concept, after doing some research I'm worried about investing a lot of time into something so recent with limited learning resources and documentation. I'm looking for advice and resources (books, articles) related to this topic. Thanks in advance!

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• Vim and clang_complete, how to explicitly compile my code

  - by puller

  I use Vim with clang_complete for omnicompletion. The plugin is automatically triggered when I need completion, e.g., after I type . or -> to access an object members or methods (see attached screenshot). The plugin works really nice, however I would need a way to trigger it manually (i.e. to compile my code for syntax checking). This is useful for two reasons: Static syntax checking Clear previous errors which have been fixed (which otherwise will remain in their buffer). See the two screenshots below for a better understanding. Any help is appreciated. Thanks. Screenshot 1 Screenshot 2

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• using time() to measure how long a function takes

  - by hap497

  Hi, I am trying to use time() to measure various points of my program. http://www.cplusplus.com/reference/clibrary/ctime/time/ What I don't understand is why the values in the before and after are Different? I understanding this is not the best way to profile my program, I just want to see how long does something take. printf ("**MyProgram::before time= %ld\n", time(NULL)); doSomthing(); doSomthingLong(); printf ("**MyProgram::after time= %ld\n", time(NULL)); Thank you.

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• Why should "miter" joints be slower than others?

  - by Hanno Fietz

  I'm having a graphics problem on drawing lines in Flash Player, where two lines drawn on top of each other with different thickness don't align properly if I use any other JointStyle than MITER. For pictures of the effect, and for the graphics oriented part of the question, see my post over on doctype. However, there's also a second angle on this problem, which is: why should drawing the "mitered" joints be so much slower than others? This seems to be a problem since at least FP 8, but I couldn't find any detailed info on what the problem might be. Is this just an ordinary bug that didn't get fixed yet, or is there something inherently slower about drawing these joints? For example, they seem to have something to do with square roots, but I seriously lack understanding of what this joint style thing is all about, technically. It just looks like some minor detail a graphic designer might worry about. I'm asking because I'm wondering if I can do something to mitergate, er, mitigate, the problem.

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• Objective C instance variables - Newbie

  - by Dwayne King

  OK - so I'm sure my confusion here is just a result of being stuck in a "Java mindset" and not understanding how Obj C differs in this case. In Java, I can declare a variable in a class, like this, and each instance of that class will have it's own: MyClass { String myVar; MyClass() { // constructor } } In Obj C I tried to do the same thing by declaring a variable only in the .m file like this: #import "MyClass.h" @implementation MyClass NSString *testVar; @end My expectation here was that this variable has a scope limited to this class. So I created a second class (identical): #import "MySecondClass.h" @implementation MySecondClass NSString *testVar; @end What I'm seeing (and has me baffled) is that changing the variable in one class, affects the value seen in the other class. In fact, if I set a breakpoint, and then "Jump to Definition" of the variable, it takes me to th I've created an extremely small XCode project that demonstrates the problem here Nothing more humbling than moving to a new language :) Thanks in advance.

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• Which is the future of web development: HTML5 or Silverlight(or other RIA framework)?

  - by Morgan Cheng

  My colleagues have a heated debate on what is the future of web development. One side is supporting HTML5 and the other is supporting Silverlight. There is no conclusion of the debate yet. In my humble opinion as a programmer, HTML5 will not improve programming productivity, while Silverlight will. In my understanding, programmers still need to program in JavaScript to take advantage of HTML5. For Silverlight, we can use C# which is static-type language. A lot of coding defects can be found in compilation time. For HTML5, different browsers might still have different behavior even though there is spec. For Silverlight, generally what works in IE will work the same way in other browsers. Just my thoughts. Any idea on how to choose future direction of web development?

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• Why is volatile not considered useful in multithreaded C or C++ programming?

  - by Michael E

  As demonstrated in this answer I recently posted, I seem to be confused about the utility (or lack thereof) of volatile in multi-threaded programming contexts. My understanding is this: any time a variable may be changed outside the flow of control of a piece of code accessing it, that variable should be declared to be volatile. Signal handlers, I/O registers, and variables modified by another thread all constitute such situations. So, if you have a global int foo, and foo is read by one thread and set atomically by another thread (probably using an appropriate machine instruction), the reading thread sees this situation in the same way it sees a variable tweaked by a signal handler or modified by an external hardware condition and thus foo should be declared volatile (or, for multithreaded situations, accessed with memory-fenced load, which is probably a better a solution). How and where am I wrong?

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• Passing input to Ant's <exec> task

  - by mikek

  I have an Ant script running a standard -task after taking in an inputed password: <input message="Password:" addproperty="password"> <handler classname="org.apache.tools.ant.input.SecureInputHandler" /> </input> <exec executable="/bin/sh" input="${password}" failonerror="true"> <arg line='-c "myScript.sh"' /> </exec> The script myScript.sh prompts the user for a password, and, it was my understanding that from the Ant documentation that input is supposed relay input into whatever the <exec> task is executing, but instead I get (for entering the password foobar) [exec] Failed to open /usr/local/foobar which is followed by a stack trace from my script complaining about an incorrect password...so obviously I've understood the documentation wrong. Does anybody know how to handle prompted input from external scripts in Ant?

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• PHP no wait sem_acquire?

  - by SerEnder

  Not a specific code question, but more of a general coding question. I'm trying to use a semaphore in a work project to limit the number of users that can access certain processes at a concurrent time. From my understanding the following: $iKey = ftock($sSomeFileLocation,'sOneCharacterString'); //Generate the key if($sem_id = sem_get($iKey){ //1 user allowed if(sem_acquire($sem_id)){ //Do the limited process here sem_release($sem_id); } } The problem that I see here is that if there is already one user who has the semaphore key, then the next user just waits until the first user is done rather than just faulting out. Anyone know of a way that if the max_acquire number has been reached, sem_acquire (or similar) will just return false? Thanks

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• How can I speed up line by line reading of an ASCII file? (C++)

  - by Jon

  Here's a bit of code that is a considerable bottleneck after doing some measuring: //----------------------------------------------------------------------------- // Construct dictionary hash set from dictionary file //----------------------------------------------------------------------------- void constructDictionary(unordered_set<string> &dict) { ifstream wordListFile; wordListFile.open("dictionary.txt"); string word; while( wordListFile >> word ) { if( !word.empty() ) { dict.insert(word); } } wordListFile.close(); } I'm reading in ~200,000 words and this takes about 240 ms on my machine. Is the use of ifstream here efficient? Can I do better? I'm reading about mmap() implementations but I'm not understanding them 100%. The input file is simply text strings with *nix line terminations.

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• PHP: How to check for response code?

  - by Tom

  Hi, I'm a relative PHP newbie implementing a PayPal IPN listener and all seems to be working fine, except I dont really know how to check for a response code. I've tried something ugly with cURL but it doesn't work at all (I'm not understanding cURL). I've tried this piece of code that I grabbed from somewhere on the net: $fp = fsockopen('ssl://www.sandbox.paypal.com', 443, $errno, $errstr, 30); $response_headers = get_headers($fp); $response_code = (int)substr($headers[0], 9, 3); ... but it's not working (returns $response_code = 0). So right now, I'm debugging my IPN code without checking for a Response 200. Can anyone more experienced advise me on what's the proper/simple way to check this? Thanks

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• Can I correctly debug assemblies loaded with the 'AssemblyResolve' event?

  - by Thiado de Arruda

  I'm experimenting with the AppDomain's 'AssemblyResolve' event by hidding the depedencies for an executable file in another folder. The assemblies seem to beloading and executing fine, however debugging seems to be crazy, sometimes it hits my break points, sometimes it doesnt , and sometimes it hits the same code twice(It seems absurd but I'm sure the code is executing only once). I don't understanding how debuggers works but I guess it has something to do with the PDB files. Anyone got an idea of what might be happening and how can I fix it? Edit: Let me add that I'm calling methods on the dynamically loaded assemblies using reflection, sometimes the method I'm stepping over throws an exception that only pops at a later time.

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• Given a document select a relevant snippet.

  - by BCS

  When I ask a question here, the tool tips for the question returned by the auto search given the first little bit of the question, but a decent percentage of them don't give any text that is any more useful for understanding the question than the title. Does anyone have an idea about how to make a filter to trim out useless bits of a question? My first idea is to trim any leading sentences that contain only words in some list (for instance, stop words, plus words from the title, plus words from the SO corpus that have very weak correlation with tags, that is that are equally likely to occur in any question regardless of it's tags)

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• slow android emulator

  - by Andrie

  I have a 2.67GHz Celeron Processor, 1.21GBs of RAM on a x86 Windows XP Pro machine. My understanding is that the emulator should start fairly quickly on such a machine, but for me it does not. I have followed all instructions in setting up the IDE, SDKs, JDKs and such and have had some success in staring the emulator quickly but is very particulary. How can I if possible fix this problem. Even if it starts and loads home screen it is very sluggish. Any help would be appreciated guys thanks. I have tried the Eclipse IDE in Galileos, and Ganymede.

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• How do I create a Magento module or widget that will appear on the shopping cart page?

  - by user303449

  I’m having a lot of trouble understanding how to create a module that will add an extra button to the shopping cart page. I found lots of info on payment modules and stand-a-lone page modules, but nothing for this. I simply need to add a button underneath the regular “Checkout” button that can post item data to another website. I’ve created a module but can’t get Magento to recognize it and display the button on that spot. Any help would be greatly appreciated, even just sending me to an existing tutorial that I haven’t been able to find. Thanks.

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• How can I (is there a way to) convert an HRESULT into a system specific error message?

  - by Billy ONeal

  According to this, there's no way to convert a HRESULT error code into a Win32 error code. Therefore (at least to my understanding), my use of FormatMessage in order to generate error messages (i.e. std::wstring Exception::GetWideMessage() const { using std::tr1::shared_ptr; shared_ptr<void> buff; LPWSTR buffPtr; DWORD bufferLength = FormatMessageW( FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, GetErrorCode(), 0, reinterpret_cast<LPWSTR>(&buffPtr), 0, NULL); buff.reset(buffPtr, LocalFreeHelper()); return std::wstring(buffPtr, bufferLength); } ) does not work for HRESULTs. How do I generate these kinds of system-specific error strings for HRESULTs?

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• WPF: Creating instances of resources?

  - by oakskc

  I'm brand spanking new to WPF and am trying to play around with projects to better understand what I'm reading. My understanding of a resource is that it is the instance, you can't use it like a factory and create instances of it. For example, a XAML-defined rectangle. You can reference it, but you can't have numerous instances of it all over the surface. In WPF, what would be the way to do that? If I define a Rectangle as a resource with specific properties and wanted to have multiple instances of that within a dynamically-generated grid, how should I be going about it? Or is there a different way I should be trying to do this? Purely academic exercise with no real-world application.

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• memset on array of structures in C++

  - by garry

  I have another memset question. It appears as if the code I am editing may have some issues (or it's not done the same way in different files) A::LRM las[9]; //A and LRM are both structures with BOOLS and INTS memset(&las, 0, sizeof(las)); typedef Sec SecArray[16]; SecArray rad_array; memset(rad_array, 0, sizeof(SecArray)); The second example appears to be correct because rad_array is the same as the first position in the array. Then the sizeof(SecArray)) would make sense. The first one doesn't seem correct to me. All structs are just BOOLs and INTS nothing dynamic in them. My understanding from my other post about memset was that it followed this format. memset("pointer to object", "what to set it to", "size of object") Can anyone tell me what exactly is going on here if I am incorrect with my theory.

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• Logical Programming Problem

  - by user353060

  Hello, I've been trying to solve this problem for quite sometime but I am having trouble with it. Let's say on a trigger, you receive values. First trigger: You get 1 Second trigger: You get 1, 2 Third trigger: You get 1, 2, 3 So, I store 1. For 2nd trigger, I store 2 since 1 already exist. For 3rd trigger, I store 3 since 1,2 already exist so in total I have stored 1,2,3 As you can see, we can easily check for new values, if old != new. Here's come the problem: Fourth trigger: You get 1, 2, 4 For 4th trigger, I store 1, 2 because it exists but how do I check against 3 and remove 3 from store and check if 4 is new? If you are having problems understanding this, feel free to clarify. Thanks!

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