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• jQuery CSS plugin that returns computed style of element to pseudo clone that element?

  - by Keith Bentrup

  I'm looking for a way using jQuery to return an object of computed styles for the 1st matched element. I could then pass this object to another call of jQuery's css method. For example, with width, I can do the following to make the 2 divs have the same width: $('#div2').width($('#div1').width()); It would be nice if I could make a text input look like an existing span: $('#input1').css($('#span1').css()); where .css() with no argument returns an object that can be passed to .css(obj). (I can't find a jQuery plugin for this, but it seems like it should exist. If it doesn't exist, I'll turn mine below into a plugin and post it with all the properties that I use.) Basically, I want to pseudo clone certain elements but use a different tag. For example, I have an li element that I want to hide and put an input element over it that looks the same. When the user types, it looks like they are editing the element inline. I'm also open to other approaches for this pseudo cloning problem for editing. Any suggestions? Here's what I currently have. The only problem is just getting all the possible styles. This could be a ridiculously long list. jQuery.fn.css2 = jQuery.fn.css; jQuery.fn.css = function() { if (arguments.length) return jQuery.fn.css2.apply(this, arguments); var attr = ['font-family','font-size','font-weight','font-style','color', 'text-transform','text-decoration','letter-spacing','word-spacing', 'line-height','text-align','vertical-align','direction','background-color', 'background-image','background-repeat','background-position', 'background-attachment','opacity','width','height','top','right','bottom', 'left','margin-top','margin-right','margin-bottom','margin-left', 'padding-top','padding-right','padding-bottom','padding-left', 'border-top-width','border-right-width','border-bottom-width', 'border-left-width','border-top-color','border-right-color', 'border-bottom-color','border-left-color','border-top-style', 'border-right-style','border-bottom-style','border-left-style','position', 'display','visibility','z-index','overflow-x','overflow-y','white-space', 'clip','float','clear','cursor','list-style-image','list-style-position', 'list-style-type','marker-offset']; var len = attr.length, obj = {}; for (var i = 0; i < len; i++) obj[attr[i]] = jQuery.fn.css2.call(this, attr[i]); return obj; } Edit: I've now been using the code above for awhile. It works well and behaves exactly like the original css method with one exception: if 0 args are passed, it returns the computed style object. As you can see, it immediately calls the original css method if that's the case that applies. Otherwise, it gets the computed styles of all the listed properties (gathered from Firebug's computed style list). Although it's getting a long list of values, it's quite fast. Hope it's useful to others.

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• WPF MVVM Pattern, ViewModel DataContext question

  - by orangecl4now

  I used this side to create my demo application http://windowsclient.net/learn/video.aspx?v=314683 The site was very useful in getting my started and in their example, they created a file called EmployeeRepository.cs which appears to be the source for the data. In their example, the data was hard-wired in code. So I'm trying to learn how to get the data from a data source (like a DB). In my specific case, I want to get the data from a Microsoft Access DB. (READ ONLY, So I'll only use SELECT commands). using System.Collections.Generic; using Telephone_Directory_2010.Model; namespace Telephone_Directory_2010.DataAccess { public class EmployeeRepository { readonly List<Employee> _employees; public EmployeeRepository() { if (_employees == null) { _employees = new List<Employee>(); } _employees.Add(Employee.CreateEmployee("Student One", "IT201", "Information Technology", "IT4207", "Building1", "Room650")); _employees.Add(Employee.CreateEmployee("Student Two", "IT201", "Information Technology", "IT4207", "Building1", "Room650")); _employees.Add(Employee.CreateEmployee("Student Three", "IT201", "Information Technology", "IT4207", "Building1", "Room650")); } public List<Employee> GetEmployees() { return new List<Employee>(_employees); } } } I found another example where an Access DB is used but it doesn't comply with MVVM. So I was trying to figure out how to add the DB file to the project, how to wire it up and bind it to a listbox (i'm not that far yet). Below is my modified file using System.Collections.Generic; using Telephone_Directory_2010.Model; // integrating new code with working code using Telephone_Directory_2010.telephone2010DataSetTableAdapters; using System.Windows.Data; namespace Telephone_Directory_2010.DataAccess { public class EmployeeRepository { readonly List<Employee> _employees; // start // integrating new code with working code private telephone2010DataSet.telephone2010DataTable employeeTable; private CollectionView dataView; internal CollectionView DataView { get { if (dataView == null) { dataView = (CollectionView) CollectionViewSource.GetDefaultView(this.DataContext); } return dataView; } } public EmployeeRepository() { if (_employees == null) { _employees = new List<Employee>(); } telephone2010TableAdapter employeeTableAdapter = new telephone2010TableAdapter(); employeeTable = employeeTableAdapter.GetData(); this.DataContext = employeeTable; } public List<Employee> GetEmployees() { return new List<Employee>(_employees); } } } I get the following error messages when building Error 1 'Telephone_Directory_2010.DataAccess.EmployeeRepository' does not contain a definition for 'DataContext' and no extension method 'DataContext' accepting a first argument of type 'Telephone_Directory_2010.DataAccess.EmployeeRepository' could be found (are you missing a using directive or an assembly reference?) C:\Projects\VS2010\Telephone Directory 2010\Telephone Directory 2010\DataAccess\EmployeeRepository.cs 23 90 Telephone Directory 2010

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• Singleton: How should it be used

  - by Loki Astari

  Edit: From another question I provided an answer that has links to a lot of questions/answers about singeltons: More info about singletons here: So I have read the thread Singletons: good design or a crutch? And the argument still rages. I see Singletons as a Design Pattern (good and bad). The problem with Singleton is not the Pattern but rather the users (sorry everybody). Everybody and their father thinks they can implement one correctly (and from the many interviews I have done, most people can't). Also because everybody thinks they can implement a correct Singleton they abuse the Pattern and use it in situations that are not appropriate (replacing global variables with Singletons!). So the main questions that need to be answered are: When should you use a Singleton How do you implement a Singleton correctly My hope for this article is that we can collect together in a single place (rather than having to google and search multiple sites) an authoritative source of when (and then how) to use a Singleton correctly. Also appropriate would be a list of Anti-Usages and common bad implementations explaining why they fail to work and for good implementations their weaknesses. So get the ball rolling: I will hold my hand up and say this is what I use but probably has problems. I like "Scott Myers" handling of the subject in his books "Effective C++" Good Situations to use Singletons (not many): Logging frameworks Thread recycling pools /* * C++ Singleton * Limitation: Single Threaded Design * See: http://www.aristeia.com/Papers/DDJ_Jul_Aug_2004_revised.pdf * For problems associated with locking in multi threaded applications * * Limitation: * If you use this Singleton (A) within a destructor of another Singleton (B) * This Singleton (A) must be fully constructed before the constructor of (B) * is called. */ class MySingleton { private: // Private Constructor MySingleton(); // Stop the compiler generating methods of copy the object MySingleton(MySingleton const& copy); // Not Implemented MySingleton& operator=(MySingleton const& copy); // Not Implemented public: static MySingleton& getInstance() { // The only instance // Guaranteed to be lazy initialized // Guaranteed that it will be destroyed correctly static MySingleton instance; return instance; } }; OK. Lets get some criticism and other implementations together. :-)

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• How to find minimum of nonlinear, multivariate function using Newton's method (code not linear algeb

  - by Norman Ramsey

  I'm trying to do some parameter estimation and want to choose parameter estimates that minimize the square error in a predicted equation over about 30 variables. If the equation were linear, I would just compute the 30 partial derivatives, set them all to zero, and use a linear-equation solver. But unfortunately the equation is nonlinear and so are its derivatives. If the equation were over a single variable, I would just use Newton's method (also known as Newton-Raphson). The Web is rich in examples and code to implement Newton's method for functions of a single variable. Given that I have about 30 variables, how can I program a numeric solution to this problem using Newton's method? I have the equation in closed form and can compute the first and second derivatives, but I don't know quite how to proceed from there. I have found a large number of treatments on the web, but they quickly get into heavy matrix notation. I've found something moderately helpful on Wikipedia, but I'm having trouble translating it into code. Where I'm worried about breaking down is in the matrix algebra and matrix inversions. I can invert a matrix with a linear-equation solver but I'm worried about getting the right rows and columns, avoiding transposition errors, and so on. To be quite concrete: I want to work with tables mapping variables to their values. I can write a function of such a table that returns the square error given such a table as argument. I can also create functions that return a partial derivative with respect to any given variable. I have a reasonable starting estimate for the values in the table, so I'm not worried about convergence. I'm not sure how to write the loop that uses an estimate (table of value for each variable), the function, and a table of partial-derivative functions to produce a new estimate. That last is what I'd like help with. Any direct help or pointers to good sources will be warmly appreciated. Edit: Since I have the first and second derivatives in closed form, I would like to take advantage of them and avoid more slowly converging methods like simplex searches.

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• Problem in running boost eample blocking_udp_echo_client on MacOSX

  - by n179911

  I am trying to run blocking_udp_echo_client on MacOS X http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/example/echo/blocking_udp_echo_client.cpp I run it with argument 'localhost 9000' But the program crashes and this is the line in the source which crashes: `udp::socket s(io_service, udp::endpoint(udp::v4(), 0));' this is the stack trace: #0 0x918c3e42 in __kill #1 0x918c3e34 in kill$UNIX2003 #2 0x9193623a in raise #3 0x91942679 in abort #4 0x940d96f9 in __gnu_debug::_Error_formatter::_M_error #5 0x0000e76e in __gnu_debug::_Safe_iterator::op_base* , __gnu_debug_def::list::op_base*, std::allocator::op_base* ::_Safe_iterator at safe_iterator.h:124 #6 0x00014729 in boost::asio::detail::hash_map::op_base*::bucket_type::bucket_type at hash_map.hpp:277 #7 0x00019e97 in std::_Construct::op_base*::bucket_type, boost::asio::detail::hash_map::op_base*::bucket_type at stl_construct.h:81 #8 0x0001a457 in std::__uninitialized_fill_n_aux::op_base*::bucket_type*, __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type , unsigned long, boost::asio::detail::hash_map::op_base*::bucket_type at stl_uninitialized.h:194 #9 0x0001a4e1 in std::uninitialized_fill_n::op_base*::bucket_type*, __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type , unsigned long, boost::asio::detail::hash_map::op_base*::bucket_type at stl_uninitialized.h:218 #10 0x0001a509 in std::__uninitialized_fill_n_a::op_base*::bucket_type*, __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type , unsigned long, boost::asio::detail::hash_map::op_base*::bucket_type, boost::asio::detail::hash_map::op_base*::bucket_type at stl_uninitialized.h:310 #11 0x0001aa34 in __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type ::_M_fill_insert at vector.tcc:365 #12 0x0001acda in __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type ::insert at stl_vector.h:658 #13 0x0001ad81 in __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type ::resize at stl_vector.h:427 #14 0x0001ae3a in __gnu_debug_def::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type ::resize at vector:169 #15 0x0001b7be in boost::asio::detail::hash_map::op_base*::rehash at hash_map.hpp:221 #16 0x0001bbeb in boost::asio::detail::hash_map::op_base*::hash_map at hash_map.hpp:67 #17 0x0001bc74 in boost::asio::detail::reactor_op_queue::reactor_op_queue at reactor_op_queue.hpp:42 #18 0x0001bd24 in boost::asio::detail::kqueue_reactor::kqueue_reactor at kqueue_reactor.hpp:86 #19 0x0001c000 in boost::asio::detail::service_registry::use_service at service_registry.hpp:109 #20 0x0001c14d in boost::asio::use_service at io_service.ipp:195 #21 0x0001c26d in boost::asio::detail::reactive_socket_service ::reactive_socket_service at reactive_socket_service.hpp:111 #22 0x0001c344 in boost::asio::detail::service_registry::use_service at service_registry.hpp:109 #23 0x0001c491 in boost::asio::use_service at io_service.ipp:195 #24 0x0001c4d5 in boost::asio::datagram_socket_service::datagram_socket_service at datagram_socket_service.hpp:95 #25 0x0001c59e in boost::asio::detail::service_registry::use_service at service_registry.hpp:109 #26 0x0001c6eb in boost::asio::use_service at io_service.ipp:195 #27 0x0001c711 in boost::asio::basic_io_object ::basic_io_object at basic_io_object.hpp:72 #28 0x0001c783 in boost::asio::basic_socket ::basic_socket at basic_socket.hpp:108 #29 0x0001c865 in boost::asio::basic_datagram_socket ::basic_datagram_socket at basic_datagram_socket.hpp:107 #30 0x000027bc in main at main.cpp:32 This is the gdb output: (gdb) continue /Developer/SDKs/MacOSX10.5.sdk/usr/include/c++/4.0.0/debug/safe_iterator.h:127: error: attempt to copy-construct an iterator from a singular iterator. Objects involved in the operation: iterator "this" @ 0x0x100420 { type = N11__gnu_debug14_Safe_iteratorIN10__gnu_norm14_List_iteratorISt4pairIiPN5boost4asio6detail16reactor_op_queueIiE7op_baseEEEEN15__gnu_debug_def4listISB_SaISB_EEEEE (mutable iterator); state = singular; } iterator "other" @ 0x0xbfffe8a4 { type = N11__gnu_debug14_Safe_iteratorIN10__gnu_norm14_List_iteratorISt4pairIiPN5boost4asio6detail16reactor_op_queueIiE7op_baseEEEEN15__gnu_debug_def4listISB_SaISB_EEEEE (mutable iterator); state = singular; } Program received signal: “SIGABRT”. (gdb) continue Program received signal: “?”. Does someone has any idea why this example does not work on mac osx? Thank you.

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• Problems integrating nServiceBus with StructureMap

  - by SimonB

  I'm trying to use StructureMap with nServiceBus. The Project: Uses a GenericHost Endpoint to send command messages Configures nServiceBus using the StructMapBuilder. Uses a simple StructureMap registry config Uses a start up class TestServer supporting IWantToRunAtStartup The TestServer class has ctor dependency on a TestManager class The TestManager class has ctor dependency on IBus ObjectFactory.WhatDoIHave() shows StructureMap knows how to construct the classes. When run I get buildup errors. nServiceBus seems to be overwriting the config? Note that when I add a IBus ctor depenendency to my event handlers without any other config all appears fine. Error: Exception when starting endpoint, error has been logged. Reason: Error creating object with name 'nSeviceBusStructureMapTest.TestServer' : Unsatisfied dependency expressed through constructor argument with index 0 of type [nSeviceBusStructureMapTest.ITestManager] : No unique object of type [nSeviceBusStructureMapTest.ITestManager] is defined : Unsatisfied dependency of type [nSeviceBusStructureMapTest.ITestManager]: expected at least 1 matching object to wire the [miningServiceManage] parameter on the constructor of object [nSeviceBusStructureMapTest.TestServer] Source: using System; using System.Diagnostics; using NServiceBus; using StructureMap; using StructureMap.Configuration.DSL; namespace nSeviceBusStructureMapTest { public class TestSmRegistry : Registry { public TestSmRegistry() { For<ITestManager>().Use<TestManager>(); For<TestServer>().Use<TestServer>(); } } public class TestEndPoint : AsA_Server, IConfigureThisEndpoint, IWantCustomLogging { public void Init() { Configure.With().StructureMapBuilder(ObjectFactory.Container); ObjectFactory.Configure(c => c.AddRegistry<TestSmRegistry>()); Debug.WriteLine(ObjectFactory.WhatDoIHave()); } } public class TestServer : IWantToRunAtStartup { public TestServer(ITestManager miningServiceManage) { _miningServiceManage = miningServiceManage; } private readonly ITestManager _miningServiceManage; public void Run() { _miningServiceManage.Run(); } public void Stop() { } } public interface ITestManager { void Run(); } public class TestManager : ITestManager { public TestManager(IBus bus) { _bus = bus; } private readonly IBus _bus; public void Run() { if (_bus == null) Debug.WriteLine("Error no bus"); // Send messages on bus; } } } <MsmqTransportConfig InputQueue="test" ErrorQueue="error" NumberOfWorkerThreads="1" MaxRetries="5" /> <UnicastBusConfig> <MessageEndpointMappings> </MessageEndpointMappings> </UnicastBusConfig> Any ideas?

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• PyQt threads and signals - how to properly retrieve values

  - by Cawas

  Using Python 2.5 and PyQt, I couldn't find any question this specific in Python, so sorry if I'm repeating the other Qt referenced questions below, but I couldn't easily understand that C code. I've got two classes, a GUI and a thread, and I'm trying to get return values from the thread. I've used the link in here as base to write my code, which is working just fine. To sum it up and illustrate the question in code here (I don't think this code will run on itself): class MainWindow (QtGui.QWidget): # this is just a reference and not really relevant to the question def __init__ (self, parent = None): QtGui.QWidget.__init__(self, parent) self.thread = Worker() # this does not begin a thread - look at "Worker.run" for mor details self.connect(self.thread, QtCore.SIGNAL('finished()'), self.unfreezeUi) self.connect(self.thread, QtCore.SIGNAL('terminated()'), self.unfreezeUi) self.connect(self.buttonDaemon, QtCore.SIGNAL('clicked()'), self.pressDaemon) # the problem begins below: I'm not using signals, or queue, or whatever, while I believe I should def pressDaemon (self): self.buttonDaemon.setEnabled(False) if self.thread.isDaemonRunning(): self.thread.setDaemonStopSignal(True) self.buttonDaemon.setText('Daemon - converts every %s sec'% args['daemonInterval']) else: self.buttonConvert.setEnabled(False) self.thread.startDaemon() self.buttonDaemon.setText('Stop Daemon') self.buttonDaemon.setEnabled(True) # this whole class is just another reference class Worker (QtCore.QThread): daemonIsRunning = False daemonStopSignal = False daemonCurrentDelay = 0 def isDaemonRunning (self): return self.daemonIsRunning def setDaemonStopSignal (self, bool): self.daemonStopSignal = bool def __init__ (self, parent = None): QtCore.QThread.__init__(self, parent) self.exiting = False self.thread_to_run = None # which def will be running def __del__ (self): self.exiting = True self.thread_to_run = None self.wait() def run (self): if self.thread_to_run != None: self.thread_to_run(mode='continue') def startDaemon (self, mode = 'run'): if mode == 'run': self.thread_to_run = self.startDaemon # I'd love to be able to just pass this as an argument on start() below return self.start() # this will begin the thread # this is where the thread actually begins self.daemonIsRunning = True self.daemonStopSignal = False sleepStep = 0.1 # don't know how to interrupt while sleeping - so the less sleepStep, the faster StopSignal will work # begins the daemon in an "infinite" loop while self.daemonStopSignal == False and not self.exiting: # here, do any kind of daemon service delay = 0 while self.daemonStopSignal == False and not self.exiting and delay < args['daemonInterval']: time.sleep(sleepStep) # delay is actually set by while, but this holds for N second delay += sleepStep # daemon stopped, reseting everything self.daemonIsRunning = False self.emit(QtCore.SIGNAL('terminated')) Tho it's quite big, I hope this is pretty clear. The main point is on def pressDaemon. Specifically all 3 self.thread calls. The last one, self.thread.startDaemon() is just fine, and exactly as the example. I doubt that represents any issue. The problem is being able to set the Daemon Stop Signal and retrieve the value if it's running. I'm not sure that it's possible to set a stop signal on QtCore.QtThread, because I've tried doing the same way and it didn't work. But I'm pretty sure it's not possible to retrieve a return result from the emit. So, there it is. I'm using direct calls to the thread class, and I'm almost positive that's not a good design and will probably fail when running under stress. I read about that queue, but I'm not sure it's the proper solution here, or if I should be using Qt at all, since this is Python. And just maybe there's nothing wrong with the way I'm doing.

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• Code Golf: Evaluating Mathematical Expressions

  - by Noldorin

  Challenge Here is the challenge (of my own invention, though I wouldn't be surprised if it has previously appeared elsewhere on the web). Write a function that takes a single argument that is a string representation of a simple mathematical expression and evaluates it as a floating point value. A "simple expression" may include any of the following: positive or negative decimal numbers, +, -, *, /, (, ). Expressions use (normal) infix notation. Operators should be evaluated in the order they appear, i.e. not as in BODMAS, though brackets should be correctly observed, of course. The function should return the correct result for any possible expression of this form. However, the function does not have to handle malformed expressions (i.e. ones with bad syntax). Examples of expressions: 1 + 3 / -8 = -0.5 (No BODMAS) 2*3*4*5+99 = 219 4 * (9 - 4) / (2 * 6 - 2) + 8 = 10 1 + ((123 * 3 - 69) / 100) = 4 2.45/8.5*9.27+(5*0.0023) = 2.68... Rules I anticipate some form of "cheating"/craftiness here, so please let me forewarn against it! By cheating, I refer to the use of the eval or equivalent function in dynamic languages such as JavaScript or PHP, or equally compiling and executing code on the fly. (I think my specification of "no BODMAS" has pretty much guaranteed this however.) Apart from that, there are no restrictions. I anticipate a few Regex solutions here, but it would be nice to see more than just that. Now, I'm mainly interested in a C#/.NET solution here, but any other language would be perfectly acceptable too (in particular, F# and Python for the functional/mixed approaches). I haven't yet decided whether I'm going to accept the shortest or most ingenious solution (at least for the language) as the answer, but I would welcome any form of solution in any language, except what I've just prohibited above! My Solution I've now posted my C# solution here (403 chars). Update: My new solution has beaten the old one significantly at 294 chars, with the help of a bit of lovely regex! I suspected that this will get easily beaten by some of the languages out there with lighter syntax (particularly the funcional/dynamic ones), and have been proved right, but I'd be curious if someone could beat this in C# still. Update I've seen some very crafty solutions already. Thanks to everyone who has posted one. Although I haven't tested any of them yet, I'm going to trust people and assume they at least work with all of the given examples. Just for the note, re-entrancy (i.e. thread-safety) is not a requirement for the function, though it is a bonus. Format Please post all answers in the following format for the purpose of easy comparison: Language Number of characters: ??? Fully obfuscated function: (code here) Clear/semi-obfuscated function: (code here) Any notes on the algorithm/clever shortcuts it takes.

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• Miller-rabin exception number?

  - by nightcracker

  Hey everyone. This question is about the number 169716931325235658326303. According to http://www.alpertron.com.ar/ECM.HTM it is prime. According to my miller-rabin implementation in python with 7 repetitions is is composite. With 50 repetitions it is still composite. With 5000 repetitions it is STILL composite. I thought, this might be a problem of my implementation. So I tried GNU MP bignum library, which has a miller-rabin primality test built-in. I tested with 1000000 repetitions. Still composite. This is my implementation of the miller-rabin primality test: def isprime(n, precision=7): if n == 1 or n % 2 == 0: return False elif n < 1: raise ValueError("Out of bounds, first argument must be > 0") d = n - 1 s = 0 while d % 2 == 0: d //= 2 s += 1 for repeat in range(precision): a = random.randrange(2, n - 2) x = pow(a, d, n) if x == 1 or x == n - 1: continue for r in range(s - 1): x = pow(x, 2, n) if x == 1: return False if x == n - 1: break else: return False return True And the code for the GMP test: #include <gmp.h> #include <stdio.h> int main(int argc, char* argv[]) { mpz_t test; mpz_init_set_str(test, "169716931325235658326303", 10); printf("%d\n", mpz_probab_prime_p(test, 1000000)); mpz_clear(test); return 0; } As far as I know there are no "exceptions" (which return false positives for any amount of repetitions) to the miller-rabin primality test. Have I stumpled upon one? Is my computer broken? Is the Elliptic Curve Method wrong? What is happening here? EDIT I found the issue, which is http://www.alpertron.com.ar/ECM.HTM. I trusted this applet, I'll contact the author his applet's implementation of the ECM is faulty for this number. Thanks. EDIT2 Hah, the shame! In the end it was something that went wrong with copy/pasting on my side. NOR the applet NOR the miller-rabin algorithm NOR my implementation NOR gmp's implementation of it is wrong, the only thing that's wrong is me. I'm sorry.

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• who free's setvbuf buffer?

  - by Evan Teran

  So I've been digging into how the stdio portion of libc is implemented and I've come across another question. Looking at man setvbuf I see the following: When the first I/O operation occurs on a file, malloc(3) is called, and a buffer is obtained. This makes sense, your program should have a malloc in it for I/O unless you actually use it. My gut reaction to this is that libc will clean up its own mess here. Which I can only assume it does because valgrind reports no memory leaks (they could of course do something dirty and not allocate it via malloc directly... but we'll assume that it literally uses malloc for now). But, you can specify your own buffer too... int main() { char *p = malloc(100); setvbuf(stdio, p, _IOFBF, 100); puts("hello world"); } Oh no, memory leak! valgrind confirms it. So it seems that whenever stdio allocates a buffer on its own, it will get deleted automatically (at the latest on program exit, but perhaps on stream close). But if you specify the buffer explicitly, then you must clean it up yourself. There is a catch though. The man page also says this: You must make sure that the space that buf points to still exists by the time stream is closed, which also happens at program termination. For example, the following is invalid: Now this is getting interesting for the standard streams. How would one properly clean up a manually allocated buffer for them, since they are closed in program termination? I could imagine a "clean this up when I close flag" inside the file struct, but it get hairy because if I read this right doing something like this: setvbuf(stdio, 0, _IOFBF, 100); printf("hello "); setvbuf(stdio, 0, _IOLBF, 100); printf("world\n"); would cause 2 allocations by the standard library because of this sentence: If the argument buf is NULL, only the mode is affected; a new buffer will be allocated on the next read or write operation.

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• Boost Python - Limits to the number of arguments when wrapping a function

  - by Derek

  I'm using Boost Python to wrap some C++ functions that I've created. One of my C++ functions contains 22 arguments. Boost complains when I try to compile my solution with this function, and I'm trying to figure out if it is just because this function has too many arguments. Does anyone know if such a limit exists? I've copied the error I'm getting below, not the code because I figure someone either knows the answer to this or not - and if there is no limit then I'll just try to figure it out myself. Thanks very much in advance! Here is a copy of the beginning of the error message I receive... 1>main.cpp 1>c:\cpp_ext\boost\boost_1_47\boost\python\make_function.hpp(76): error C2780: 'boost::mpl::vector17<RT,most_derived<Target,ClassT>::type&,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14> boost::python::detail::get_signature(RT (__thiscall ClassT::* )(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) volatile const,Target *)' : expects 2 arguments - 1 provided 1>c:\cpp_ext\boost\boost_1_47\boost\python\signature.hpp(236) : see declaration of 'boost::python::detail::get_signature' And eventually I get about a hundred copies of error messages very much resembling this one: 1>c:\cpp_ext\boost\boost_1_47\boost\python\make_function.hpp(76): error C2784: 'boost::mpl::vector17<RT,ClassT&,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14> boost::python::detail::get_signature(RT (__thiscall ClassT::* )(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) volatile const)' : could not deduce template argument for 'RT (__thiscall ClassT::* )(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) volatile const' from 'std::string (__cdecl *)(const std::string &,jal::date::JULIAN_DATE,const std::string &,const std::string &,int,const std::string &,const std::string &,const std::string &,const std::string &,const std::string &,const std::string &,int,const std::string &,const std::string &,int,const std::string &,const std::string &,const std::string &,const std::string &,const std::string &,int,const std::string &)' 1> c:\cpp_ext\boost\boost_1_47\boost\python\signature.hpp(218) : see declaration of 'boost::python::detail::get_signature' 1>c:\cpp_ext\boost\boost_1_47\boost\python\make_function.hpp(76): error C2780: 'boost::mpl::vector17<RT,most_derived<Target,ClassT>::type&,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14> boost::python::detail::get_signature(RT (__thiscall ClassT::* )(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) volatile,Target *)' : expects 2 arguments - 1 provided 1> c:\cpp_ext\boost\boost_1_47\boost\python\signature.hpp(236) : see declaration of 'boost::python::detail::get_signature'

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• Resizing an image using mouse dragging (C#)

  - by Gaax

  Hi all. I'm having some trouble resizing an image just by dragging the mouse. I found an average resize method and now am trying to modify it to use the mouse instead of given values. The way I'm doing it makes sense to me but maybe you guys can give me some better ideas. I'm basically using the distance between the current location of the mouse and the previous location of the mouse as the scaling factor. If the distance between the current mouse location and the center of of the image is less than the distance between previous mouse location and the center of the image then the image gets smaller, and vice-versa. With the code below I'm getting an Argument Exception (invalid parameter) when creating the new bitmap with the new height and width and I really don't understand why... any ideas? private static Image resizeImage(Image imgToResize, System.Drawing.Point prevMouseLoc, System.Drawing.Point currentMouseLoc) { int sourceWidth = imgToResize.Width; int sourceHeight = imgToResize.Height; float dCurrCent = 0; //Distance between current mouse location and the center of the image float dPrevCent = 0; //Distance between previous mouse location and the center of the image float dCurrPrev = 0; //Distance between current mouse location and the previous mouse location int sign = 1; System.Drawing.Point imgCenter = new System.Drawing.Point(); float nPercent = 0; imgCenter.X = imgToResize.Width / 2; imgCenter.Y = imgToResize.Height / 2; // Calculating the distance between the current mouse location and the center of the image dCurrCent = (float)Math.Sqrt(Math.Pow(currentMouseLoc.X - imgCenter.X, 2) + Math.Pow(currentMouseLoc.Y - imgCenter.Y, 2)); // Calculating the distance between the previous mouse location and the center of the image dPrevCent = (float)Math.Sqrt(Math.Pow(prevMouseLoc.XimgCenter.X,2) + Math.Pow(prevMouseLoc.Y - imgCenter.Y, 2)); // Calculating the sign value if (dCurrCent >= dPrevCent) { sign = 1; } else { sign = -1; } nPercent = sign * (float)Math.Sqrt(Math.Pow(currentMouseLoc.X - prevMouseLoc.X, 2) + Math.Pow(currentMouseLoc.Y - prevMouseLoc.Y, 2)); int destWidth = (int)(sourceWidth * nPercent); int destHeight = (int)(sourceHeight * nPercent); Bitmap b = new Bitmap(destWidth, destHeight); // exception thrown here Graphics g = Graphics.FromImage((Image)b); g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.DrawImage(imgToResize, 0, 0, destWidth, destHeight); g.Dispose(); return (Image)b; }

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• How to use objetcs as modules/functors in Scala?

  - by Jeff

  Hi. I want to use object instances as modules/functors, more or less as shown below: abstract class Lattice[E] extends Set[E] { val minimum: E val maximum: E def meet(x: E, y: E): E def join(x: E, y: E): E def neg(x: E): E } class Calculus[E](val lat: Lattice[E]) { abstract class Expr case class Var(name: String) extends Expr {...} case class Val(value: E) extends Expr {...} case class Neg(e1: Expr) extends Expr {...} case class Cnj(e1: Expr, e2: Expr) extends Expr {...} case class Dsj(e1: Expr, e2: Expr) extends Expr {...} } So that I can create a different calculus instance for each lattice (the operations I will perform need the information of which are the maximum and minimum values of the lattice). I want to be able to mix expressions of the same calculus but not be allowed to mix expressions of different ones. So far, so good. I can create my calculus instances, but problem is that I can not write functions in other classes that manipulate them. For example, I am trying to create a parser to read expressions from a file and return them; I also was trying to write an random expression generator to use in my tests with ScalaCheck. Turns out that every time a function generates an Expr object I can't use it outside the function. Even if I create the Calculus instance and pass it as an argument to the function that will in turn generate the Expr objects, the return of the function is not recognized as being of the same type of the objects created outside the function. Maybe my english is not clear enough, let me try a toy example of what I would like to do (not the real ScalaCheck generator, but close enough). def genRndExpr[E](c: Calculus[E], level: Int): Calculus[E]#Expr = { if (level > MAX_LEVEL) { val select = util.Random.nextInt(2) select match { case 0 => genRndVar(c) case 1 => genRndVal(c) } } else { val select = util.Random.nextInt(3) select match { case 0 => new c.Neg(genRndExpr(c, level+1)) case 1 => new c.Dsj(genRndExpr(c, level+1), genRndExpr(c, level+1)) case 2 => new c.Cnj(genRndExpr(c, level+1), genRndExpr(c, level+1)) } } } Now, if I try to compile the above code I get lots of error: type mismatch; found : plg.mvfml.Calculus[E]#Expr required: c.Expr case 0 = new c.Neg(genRndExpr(c, level+1)) And the same happens if I try to do something like: val boolCalc = new Calculus(Bool) val e1: boolCalc.Expr = genRndExpr(boolCalc) Please note that the generator itself is not of concern, but I will need to do similar things (i.e. create and manipulate calculus instance expressions) a lot on the rest of the system. Am I doing something wrong? Is it possible to do what I want to do? Help on this matter is highly needed and appreciated. Thanks a lot in advance.

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• How can I easily maintain a cross-file JavaScript Library Development Environment

  - by John

  I have been developing a new JavaScript application which is rapidly growing in size. My entire JavaScript Application has been encapsulated inside a single function, in a single file, in a way like this: (function(){ var uniqueApplication = window.uniqueApplication = function(opts){ if (opts.featureOne) { this.featureOne = new featureOne(opts.featureOne); } if (opts.featureTwo) { this.featureTwo = new featureTwo(opts.featureTwo); } if (opts.featureThree) { this.featureThree = new featureThree(opts.featureThree); } }; var featureOne = function(options) { this.options = options; }; featureOne.prototype.myFeatureBehavior = function() { //Lots of Behaviors }; var featureTwo = function(options) { this.options = options; }; featureTwo.prototype.myFeatureBehavior = function() { //Lots of Behaviors }; var featureThree = function(options) { this.options = options; }; featureThree.prototype.myFeatureBehavior = function() { //Lots of Behaviors }; })(); In the same file after the anonymous function and execution I do something like this: (function(){ var instanceOfApplication = new uniqueApplication({ featureOne:"dataSource", featureTwo:"drawingCanvas", featureThree:3540 }); })(); Before uploading this software online I pass my JavaScript file, and all it's dependencies, into Google Closure Compiler, using just the default Compression, and then I have one nice JavaScript file ready to go online for production. This technique has worked marvelously for me - as it has created only one global footprint in the DOM and has given me a very flexible framework to grow each additional feature of the application. However - I am reaching the point where I'd really rather not keep this entire application inside one JavaScript file. I'd like to move from having one large uniqueApplication.js file during development to having a separate file for each feature in the application, featureOne.js - featureTwo.js - featureThree.js Once I have completed offline development testing, I would then like to use something, perhaps Google Closure Compiler, to combine all of these files together - however I want these files to all be compiled inside of that scope, as they are when I have them inside one file - and I would like for them to remain in the same scope during offline testing too. I see that Google Closure Compiler supports an argument for passing in modules but I haven't really been able to find a whole lot of information on doing something like this. Anybody have any idea how this could be accomplished - or any suggestions on a development practice for writing a single JavaScript Library across multiple files that still only leaves one footprint on the DOM?

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• Evaluation of CTEs in SQL Server 2005

  - by Jammer

  I have a question about how MS SQL evaluates functions inside CTEs. A couple of searches didn't turn up any results related to this issue, but I apologize if this is common knowledge and I'm just behind the curve. It wouldn't be the first time :-) This query is a simplified (and obviously less dynamic) version of what I'm actually doing, but it does exhibit the problem I'm experiencing. It looks like this: CREATE TABLE #EmployeePool(EmployeeID int, EmployeeRank int); INSERT INTO #EmployeePool(EmployeeID, EmployeeRank) SELECT 42, 1 UNION ALL SELECT 43, 2; DECLARE @NumEmployees int; SELECT @NumEmployees = COUNT(*) FROM #EmployeePool; WITH RandomizedCustomers AS ( SELECT CAST(c.Criteria AS int) AS CustomerID, dbo.fnUtil_Random(@NumEmployees) AS RandomRank FROM dbo.fnUtil_ParseCriteria(@CustomerIDs, 'int') c) SELECT rc.CustomerID, ep.EmployeeID FROM RandomizedCustomers rc JOIN #EmployeePool ep ON ep.EmployeeRank = rc.RandomRank; DROP TABLE #EmployeePool; The following can be assumed about all executions of the above: The result of dbo.fnUtil_Random() is always an int value greater than zero and less than or equal to the argument passed in. Since it's being called above with @NumEmployees which has the value 2, this function always evaluates to 1 or 2. The result of dbo.fnUtil_ParseCriteria(@CustomerIDs, 'int') produces a one-column, one-row table that contains a sql_variant with a base type of 'int' that has the value 219935. Given the above assumptions, it makes sense (to me, anyway) that the result of the expression above should always produce a two-column table containing one record - CustomerID and an EmployeeID. The CustomerID should always be the int value 219935, and the EmployeeID should be either 42 or 43. However, this is not always the case. Sometimes I get the expected single record. Other times I get two records (one for each EmployeeID), and still others I get no records. However, if I replace the RandomizedCustomers CTE with a true temp table, the problem vanishes completely. Every time I think I have an explanation for this behavior, it turns out to not make sense or be impossible, so I literally cannot explain why this would happen. Since the problem does not happen when I replace the CTE with a temp table, I can only assume it has something to do with the functions inside CTEs are evaluated during joins to that CTE. Do any of you have any theories?

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• Creating a variable list Pashua, OS X & Bash.

  - by S1syphus

  First of all, for those that don't know pashua is a tool for creating native Aqua dialog windows. An example of what a window config looks like is # pashua_run() # Define what the dialog should be like # Take a look at Pashua's Readme file for more info on the syntax conf=" # Set transparency: 0 is transparent, 1 is opaque *.transparency=0.95 # Set window title *.title = Introducing Pashua # Introductory text tb.type = text tb.default = "HELLO WORLD" tb.height = 276 tb.width = 310 tb.x = 340 tb.y = 44 if [ -e "$icon" ] then # Display Pashua's icon conf="$conf img.type = image img.x = 530 img.y = 255 img.path = $icon" fi if [ -e "$bgimg" ] then # Display background image conf="$conf bg.type = image bg.x = 30 bg.y = 2 bg.path = $bgimg" fi pashua_run "$conf" echo " tb = $tb" The problem is, Pashua can't really get output from stdout, but it can get arguments. Following on from what Dennis Williamson posted here. What ideally it should do is generate an output file based on information from a text file, To executed in pashua_run ore add the pashua_run around the window argument: count=1 while read -r i do echo "AB${count}.type = openbrowser" echo "AB${count}.label = Choose a master playlist file" echo "AB${count}.width=310" echo "AB${count}.tooltip = Blabla filesystem browser" echo "some text with a line from the file: $i" (( count++ )) done < TEST.txt >> long.txt SO the output is AB1.type = openbrowser AB1.label = Choose a master playlist file AB1.width=310 AB1.tooltip = Blabla filesystem browser some text with a line from the file: foo AB2.type = openbrowser AB2.label = Choose a master playlist file AB2.width=310 AB2.tooltip = Blabla filesystem browser some text with a line from the file: bar AB3.type = openbrowser AB3.label = Choose a master playlist file AB3.width=310 AB3.tooltip = Blabla filesystem browser some text with a line from the file: dev AB4.type = openbrowser AB4.label = Choose a master playlist file AB4.width=310 AB4.tooltip = Blabla filesystem random So if there is a clever way to get the output of that and place it into pashua run would be cool, on the fly: I.E load te contents of TEST.txt and generate the place it into pashua_run, I've tried using cat and opening the file... but because it's in Pashua_run it doesn't work, is there a smart way to break out then back in? Or the second way which I was thinking, was create get the output then append it into the middle text file containing the pashua runtime, then execute it, maybe slightly hacky, but I would imagine it will do the job. Any ideas? ++ I know I probably could make my life a lot easier, by doing this in actionscript and cocoa, although at present don't have time for such a learning curve, although I do plan to get round to it.

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• Why does Font.registerFont throw an error the second time a swf is loaded?

  - by Al Brown

  I've found an issue (in flash cs5) when using TLFTextfields and fonts shared at runtime, and I wondered if anyone has a solution. Here's the scenario. Fonts.swf: library for fonts (runtime shared DF4) Popup.swf: popup with a TLFTextfield (with text in it) using a font from Fonts.swf Main.swf : the main swf with a button that loads and unloads Popup.swf (using Loader or SafeLoader give the same results) Nice and simple, Run main.swf, click button and the popup appears with the text. Click the button again to remove the popup. All well and good now click the button again and I get the following error. ArgumentError: Error #1508: The value specified for argument font is invalid. at flash.text::Font$/registerFont() at Popup_fla::MainTimeline()[Popup_fla.MainTimeline::MainTimeline:12] I'm presuming it's happening because the font is already registered (checked when clicking before the load). Does anyone know how to get past this? If you are wondering here's my Main.as package { import fl.controls.Button; import flash.display.Loader; import flash.display.Sprite; import flash.events.Event; import flash.events.IOErrorEvent; import flash.events.MouseEvent; import flash.events.UncaughtErrorEvent; import flash.net.URLRequest; import flash.text.Font; public class Main extends Sprite { public var testPopupBtn:Button; protected var loader:Loader; public function Main() { trace("Main.Main()"); testPopupBtn.label = "open"; testPopupBtn.addEventListener(MouseEvent.CLICK, testClickHandler); } protected function testClickHandler(event:MouseEvent):void { trace("Main.testClickHandler(event)"); if(loader) { testPopupBtn.label = "open"; this.removeChild(loader); //loader.unloadAndStop(); loader = null; }else{ testPopupBtn.label = "close"; trace("Registered Fonts -->"); var fonts:Array = Font.enumerateFonts(false); for each (var font:Font in fonts) { trace("\t",font.fontName, font.fontStyle, font.fontType); } trace("<--"); loader = new Loader(); loader.uncaughtErrorEvents.addEventListener(UncaughtErrorEvent.UNCAUGHT_ERROR, uncaughtErrorHandler); this.addChild(loader); try{ loader.load(new URLRequest("Popup.swf")); }catch(e:*){ trace(e); } } } private function uncaughtErrorHandler(event:UncaughtErrorEvent):void { trace("Main.uncaughtErrorHandler(event)", event); } } }

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• Python form POST using urllib2 (also question on saving/using cookies)

  - by morpheous

  I am trying to write a function to post form data and save returned cookie info in a file so that the next time the page is visited, the cookie information is sent to the server (i.e. normal browser behavior). I wrote this relatively easily in C++ using curlib, but have spent almost an entire day trying to write this in Python, using urllib2 - and still no success. This is what I have so far: import urllib, urllib2 import logging # the path and filename to save your cookies in COOKIEFILE = 'cookies.lwp' cj = None ClientCookie = None cookielib = None logger = logging.getLogger(__name__) # Let's see if cookielib is available try: import cookielib except ImportError: logger.debug('importing cookielib failed. Trying ClientCookie') try: import ClientCookie except ImportError: logger.debug('ClientCookie isn\'t available either') urlopen = urllib2.urlopen Request = urllib2.Request else: logger.debug('imported ClientCookie succesfully') urlopen = ClientCookie.urlopen Request = ClientCookie.Request cj = ClientCookie.LWPCookieJar() else: logger.debug('Successfully imported cookielib') urlopen = urllib2.urlopen Request = urllib2.Request # This is a subclass of FileCookieJar # that has useful load and save methods cj = cookielib.LWPCookieJar() login_params = {'name': 'anon', 'password': 'pass' } def login(theurl, login_params): init_cookies(); data = urllib.urlencode(login_params) txheaders = {'User-agent' : 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'} try: # create a request object req = Request(theurl, data, txheaders) # and open it to return a handle on the url handle = urlopen(req) except IOError, e: log.debug('Failed to open "%s".' % theurl) if hasattr(e, 'code'): log.debug('Failed with error code - %s.' % e.code) elif hasattr(e, 'reason'): log.debug("The error object has the following 'reason' attribute :"+e.reason) sys.exit() else: if cj is None: log.debug('We don\'t have a cookie library available - sorry.') else: print 'These are the cookies we have received so far :' for index, cookie in enumerate(cj): print index, ' : ', cookie # save the cookies again cj.save(COOKIEFILE) #return the data return handle.read() # FIXME: I need to fix this so that it takes into account any cookie data we may have stored def get_page(*args, **query): if len(args) != 1: raise ValueError( "post_page() takes exactly 1 argument (%d given)" % len(args) ) url = args[0] query = urllib.urlencode(list(query.iteritems())) if not url.endswith('/') and query: url += '/' if query: url += "?" + query resource = urllib.urlopen(url) logger.debug('GET url "%s" => "%s", code %d' % (url, resource.url, resource.code)) return resource.read() When I attempt to log in, I pass the correct username and pwd,. yet the login fails, and no cookie data is saved. My two questions are: can anyone see whats wrong with the login() function, and how may I fix it? how may I modify the get_page() function to make use of any cookie info I have saved ?

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• Turtle Graphics as a Haskell Monad

  - by iliis

  I'm trying to implement turtle graphis in Haskell. The goal is to be able to write a function like this: draw_something = do fordward 100 right 90 forward 100 ... and then have it produce a list of points (maybe with additional properties): > draw_something (0,0) 0 -- start at (0,0) facing east (0 degrees) [(0,0), (0,100), (-100,100), ...] I have all this working in a 'normal' way, but I fail to implement it as a Haskell Monad and use the do-notation. The basic code: data State a = State (a, a) a -- (x,y), angle deriving (Show, Eq) initstate :: State Float initstate = State (0.0,0.0) 0.0 -- constrain angles to 0 to 2*pi fmod :: Float -> Float fmod a | a >= 2*pi = fmod (a-2*pi) | a < 0 = fmod (a+2*pi) | otherwise = a forward :: Float -> State Float -> [State Float] forward d (State (x,y) angle) = [State (x + d * (sin angle), y + d * (cos angle)) angle] right :: Float -> State Float -> [State Float] right d (State pos angle) = [State pos (fmod (angle+d))] bind :: [State a] -> (State a -> [State a]) -> [State a] bind xs f = xs ++ (f (head $ reverse xs)) ret :: State a -> [State a] ret x = [x] With this I can now write > [initstate] `bind` (forward 100) `bind` (right (pi/2)) `bind` (forward 100) [State (0.0,0.0) 0.0,State (0.0,100.0) 0.0,State (0.0,100.0) 1.5707964,State (100.0,99.99999) 1.5707964] And get the expected result. However I fail to implement this as an instance of Monad. instance Monad [State] where ... results in `State' is not applied to enough type arguments Expected kind `*', but `State' has kind `* -> *' In the instance declaration for `Monad [State]' And if I wrap the list in a new object data StateList a = StateList [State a] instance Monad StateList where return x = StateList [x] I get Couldn't match type `a' with `State a' `a' is a rigid type variable bound by the type signature for return :: a -> StateList a at logo.hs:38:9 In the expression: x In the first argument of `StateList', namely `[x]' In the expression: StateList [x] I tried various other versions but I never got it to run as I'd like to. What am I doing wrong? What do I understand incorrectly?

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• How to create JPA EntityMananger in Spring Context?

  - by HDave

  I have a JPA/Spring application that uses Hibernate as the JPA provider. In one portion of the code, I have to manually create a DAO in my application with the new operator rather than use Spring DI. When I do this, the @PersistenceContext annotation is not processed by Spring. In my code where I create the DAO I have an EntityManagerFactory which I used to set the entityManager as follows: @PersistenceUnit private EntityManagerFactory entityManagerFactory; MyDAO dao = new MyDAOImpl(); dao.setEntityManager(entityManagerFactory.createEntityManager()); The problem is that when I do this, I get a Hibernate error: Could not find UserTransaction in JNDI [java:comp/UserTransaction] It's as if the HibernateEntityManager never received all the settings I've configured in Spring: <bean id="myAppTestLocalEmf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="myapp-core" /> <property name="persistenceUnitPostProcessors"> <bean class="com.myapp.core.persist.util.JtaPersistenceUnitPostProcessor"> <property name="jtaDataSource" ref="myappPersistTestJdbcDataSource" /> </bean> </property> <property name="jpaProperties"> <props> <prop key="hibernate.transaction.factory_class">org.hibernate.transaction.JTATransactionFactory</prop> <prop key="hibernate.transaction.manager_lookup_class">com.atomikos.icatch.jta.hibernate3.TransactionManagerLookup</prop> </props> </property> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="showSql" value="true" /> <!-- The following use the PropertyPlaceholderConfigurer but it doesn't work in Eclipse --> <property name="database" value="$DS{hibernate.database}" /> <property name="databasePlatform" value="$DS{hibernate.dialect}" /> I am not sure, but I think the issue might be that I am not creating the entity manager correctly with the plain vanilla createEntityManager() call rather than passing in a map of properties. I say this because when Spring's LocalContainerEntityManagerFactoryBean proxy's the call to Hibernate's createEntityManager() all of the Spring configured options are missing. That is, there is no Map argument to the createEntityManager() call. Perhaps it is another problem entirely however....not sure!

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• POD global object initialization

  - by paercebal

  I've got bitten today by a bug. The following source can be copy/pasted (and then compiled) into a main.cpp file #include <iostream> // The point of SomeGlobalObject is for its // constructor to be launched before the main // ... struct SomeGlobalObject { SomeGlobalObject() ; } ; // ... // Which explains the global object SomeGlobalObject oSomeGlobalObject ; // A POD... I was hoping it would be constructed at // compile time when using an argument list struct MyPod { short m_short ; const char * const m_string ; } ; // declaration/Initialization of a MyPod array MyPod myArrayOfPod[] = { { 1, "Hello" }, { 2, "World" }, { 3, " !" } } ; // declaration/Initialization of an array of array of void * void * myArrayOfVoid[][2] = { { (void *)1, "Hello" }, { (void *)2, "World" }, { (void *)3, " !" } } ; // constructor of the global object... Launched BEFORE main SomeGlobalObject::SomeGlobalObject() { std::cout << "myArrayOfPod[0].m_short : " << myArrayOfPod[0].m_short << std::endl ; std::cout << "myArrayOfVoid[0][0] : " << myArrayOfVoid[0][0] << std::endl ; } // main... What else ? int main(int argc, char* argv[]) { return 0 ; } MyPod being a POD, I believed there would be no constructors. Only initialization at compile time. Thus, the global object SomeGlobalObject would have no problem to use the global array of PODs upon its construction. The problem is that in real life, nothing is so simple. On Visual C++ 2008 (I did not test on other compilers), upon execution myArrayOfPodis not initialized, even ifmyArrayOfVoid` is initialized. So my questions is: Are C++ compilers not supposed to initialize global PODs (including POD structures) at compilation time ? Note that I know global variable are evil, and I know that one can't be sure of the order of creation of global variables declared in different compilation units. The problem here is really the POD C-like initialization which seems to call a constructor (the default, compiler-generated one?). And to make everyone happy: This is on debug. On release, the global array of PODs is correctly initialized.

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• ASP.NET Web Service - how to handle special characters in strings?

  - by Vlorg

  To show this fundamental issue in .NET and the reason for this question, I have written a simple test web service with one method (EditString), and a consumer console app that calls it. They are both standard web service/console applications created via File/New Project, etc., so I won't list the whole code - just the methods in question: Web method: [WebMethod] public string EditString(string s, bool useSpecial) { return s + (useSpecial ? ((char)19).ToString() : ""); } [You can see it simply returns the string s if useSpecial is false. If useSpecial is true, it returns s + char 19.] Console app: TestService.Service1 service = new SCTestConsumer.TestService.Service1(); string response1 = service.EditString("hello", false); Console.WriteLine(response1); string response2 = service.EditString("hello", true); // fails! Console.WriteLine(response2); [The second response fails, because the method returns hello + a special character (ascii code 19 for argument's sake).] The error is: There is an error in XML document (1, 287) Inner exception: "'', hexadecimal value 0x13, is an invalid character. Line 1, position 287." A few points worth mentioning: The web method itself WORKS FINE when browsing directly to the ASMX file (e.g. http://localhost:2065/service1.asmx), and running the method through this (with the same parameters as in the console application) - i.e. displays XML with the string hello + char 19. Checking the serialized XML in other ways shows the special character is being encoded properly (the SERVER SIDE seems to be ok which is GOOD) So it seems the CLIENT SIDE has the issue - i.e. the .NET generated proxy class code doesn't handle special characters This is part of a bigger project where objects are passed in and out of the web methods - that contain string attributes - these are what need to work properly. i.e. we're de/serializing classes. Any suggestions for a workaround and how to implement it? Or have I completely missed something really obvious!!? Thanks in advance... PS. I've not had much luck with getting it to use CDATA tags (does .NET support these out of the box?).

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• Stack Overflow Exploit in C

  - by Fernando Gonzalez

  Hey there guys, the question is actually about stack overflows in C. I have an assigment that I can not get done for the life of me, i've looked at everything in the gdb and I just cant figure it. The question is the following: int i,n; void confused() { printf("who called me"); exit(0); } void shell_call(char *c) { printf(" ***Now calling \"%s\" shell command *** \n",c); system(c); exit(0); } void victim_func() { int a[4]; printf("[8]:%x\n", &a[8]); printf("Enter n: "); scanf("%d",&n); printf("Enter %d HEX Values \n",n); for(i=0;i<n;i++) scanf("%x",&a[i]); printf("Done reading junk numbers\n"); } int main() { printf("ls=736c --- ps = 7370 --- cal = 6c6163\n"); printf("location of confused %x \n", confused); printf("location of shell_call %x \n", shell_call); victim_func(); printf("Done, thank you\n"); } Ok, so I managed to get the first question correctly, which is to arbitrarily call one of the two functions not explicitly called in the main path. By the way, this has to be done while running the program without any modifications. I did this by running the program, setting N to 7, which gets me to the Function Pointer of the victim_func frame, I write a[7] with the memory address of confused or shell_call, and it works. (I have a 64 bit machine, thats why I have to get it to 7, since the EBI pointer is 2 ints wide, instead of 1) My question is the following, how could I control which argument gets passed to the shell_code funcion? ie. how do i write a string to char* c. The whole point is executing unix commands like "ps" etc, by running only the program. I figured writing the EBI pointer with the hex representation of "ps" and setting the arg list of shell_call to that, but that didn't work. I also tried inputing argsv arguments and setting the arg list of shell_call to the arg_list of main, but didnt work either. I think the second version should work, but i believe im not setting the arg list of the new stack frame correctly ( I did it by writing a[8] to 0, since its the first part of the functin pointer, and writing a[9]=736c and a[10]=0000, but its probably not right since those are the parameters of victim_func. So how do i access the parameters of shell_call?

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• Rendering javascript at the server side level. A good or bad idea?

  - by davidhong

  I want to make it clear first: This isn't a question in relation to server-side Javascript or running Javascript server side. This is a question regarding rendering of Javascript code (which will be executed on the client-side) from server-side code. Having said that, take a look at below ASP.net code for example: hlRemoveCategory.Attributes.Add("onclick", "return confirm('Are you sure you want to delete this?');") This is prescribing the client-side onclick event on the server-side. As oppose to: $('a[rel=remove]').bind('click', function(event) { return confirm('Are you sure you want to delete this?'); } Now the question I want to ask is: What is the benefit of rendering javascript from the server-side code? Or the vice-versa? I personally prefer the second way of hooking up client-side UI/behaviour to HTML elements for the following reasons: Server-side does what ever it needs to already, including data-validation, event delegation and etc; and What server-side sees as an event is not necessarily the same process on the client-side. i.e., there are plenty more events on client-side (just look at custom events); and What happens on client-side and on server-side, during an event, could be completely irrelevant and decoupled; and What ever happens on client-side happens on client-side, there is no need for the server to know. Server should process and run what is given to them, how the process comes to life is not really up to them to decide in the event of the client-side events; and so and so forth. These are my thoughts obviously. I want to know what others think and if there has been any discussions on this topic. Topics branching from this argument can reach: Code management: is it easier to render everything from server-side? Separation of concern: is it easier if client-side logic is separated to server-side logic? Efficiency: which is more efficient both in terms of coding and running? At the end of the day, I am trying to move my team to go towards the second approach. There are lot of old guys in this team who are afraid of this change. I just wish to convince them with the right facts and stats. Let me know your thoughts.

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• Why can't I use __getattr__ with Django models?

  - by Joshmaker

  I've seen examples online of people using __getattr__ with Django models, but whenever I try I get errors. (Django 1.2.3) I don't have any problems when I am using __getattr__ on normal objects. For example: class Post(object): def __getattr__(self, name): return 42 Works just fine... >>> from blog.models import Post >>> p = Post() >>> p.random 42 Now when I try it with a Django model: from django.db import models class Post(models.Model): def __getattr__(self, name): return 42 And test it on on the interpreter: >>> from blog.models import Post >>> p = Post() ERROR: An unexpected error occurred while tokenizing input The following traceback may be corrupted or invalid The error message is: ('EOF in multi-line statement', (6, 0)) --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /Users/josh/project/ in () /Users/josh/project/lib/python2.6/site-packages/django/db/models/base.pyc in init(self, *args, **kwargs) 338 if kwargs: 339 raise TypeError("'%s' is an invalid keyword argument for this function" % kwargs.keys()[0]) -- 340 signals.post_init.send(sender=self.class, instance=self) 341 342 def repr(self): /Users/josh/project/lib/python2.6/site-packages/django/dispatch/dispatcher.pyc in send(self, sender, **named) 160 161 for receiver in self._live_receivers(_make_id(sender)): -- 162 response = receiver(signal=self, sender=sender, **named) 163 responses.append((receiver, response)) 164 return responses /Users/josh/project/python2.6/site-packages/photologue/models.pyc in add_methods(sender, instance, signal, *args, **kwargs) 728 """ 729 if hasattr(instance, 'add_accessor_methods'): -- 730 instance.add_accessor_methods() 731 732 # connect the add_accessor_methods function to the post_init signal TypeError: 'int' object is not callable Can someone explain what is going on? EDIT: I may have been too abstract in the examples, here is some code that is closer to what I actually would use on the website: class Post(models.Model): title = models.CharField(max_length=255) slug = models.SlugField() date_published = models.DateTimeField() content = RichTextField('Content', blank=True, null=True) # Etc... Class CuratedPost(models.Model): post = models.ForeignKey('Post') position = models.PositiveSmallIntegerField() def __getattr__(self, name): ''' If the user tries to access a property of the CuratedPost, return the property of the Post instead... ''' return self.post.name # Etc... While I could create a property for each attribute of the Post class, that would lead to a lot of code duplication. Further more, that would mean anytime I add or edit a attribute of the Post class I would have to remember to make the same change to the CuratedPost class, which seems like a recipe for code rot.

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