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• Recursive N-way merge/diff algorithm for directory trees?

  - by BobMcGee

  What algorithms or Java libraries are available to do N-way, recursive diff/merge of directories? I need to be able to generate a list of folder trees that have many identical files, and have subdirectories with many similar files. I want to be able to use 2-way merge operations to quickly remove as much redundancy as possible. Goals: Find pairs of directories that have many similar files between them. Generate short list of directory pairs that can be synchronized with 2-way merge to eliminate duplicates Should operate recursively (there may be nested duplicates of higher-level directories) Run time and storage should be O(n log n) in numbers of directories and files Should be able to use an embedded DB or page to disk for processing more files than fit in memory (100,000+). Optional: generate an ancestry and change-set between folders Optional: sort the merge operations by how many duplicates they can elliminate I know how to use hashes to find duplicate files in roughly O(n) space, but I'm at a loss for how to go from this to finding partially overlapping sets between folders and their children. EDIT: some clarification The tricky part is the difference between "exact same" contents (otherwise hashing file hashes would work) and "similar" (which will not). Basically, I want to feed this algorithm at a set of directories and have it return a set of 2-way merge operations I can perform in order to reduce duplicates as much as possible with as few conflicts possible. It's effectively constructing an ancestry tree showing which folders are derived from each other. The end goal is to let me incorporate a bunch of different folders into one common tree. For example, I may have a folder holding programming projects, and then copy some of its contents to another computer to work on it. Then I might back up and intermediate version to flash drive. Except I may have 8 or 10 different versions, with slightly different organizational structures or folder names. I need to be able to merge them one step at a time, so I can chose how to incorporate changes at each step of the way. This is actually more or less what I intend to do with my utility (bring together a bunch of scattered backups from different points in time). I figure if I can do it right I may as well release it as a small open source util. I think the same tricks might be useful for comparing XML trees though.

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• multiple definition of inline function

  - by K71993

  Hi, I have gone through some posts related to this topic but was not able to sort out my doubt completly. This might be a very navie question. Code Description I have a header file "inline.h" and two translation unit "main.cpp" and "tran.cpp". Details of code are as below inline.h file details #ifndef __HEADER__ #include <stdio.h> extern inline int func1(void) { return 5; } static inline int func2(void) { return 6; } inline int func3(void) { return 7; } #endif main.c file details are below #define <stdio.h> #include <inline.h> int main(int argc, char *argv[]) { printf("%d\n",func1()); printf("%d\n",func2()); printf("%d\n",func3()); return 0; } tran.cpp file details (Not that the functions are not inline here) #include <stdio.h> int func1(void) { return 500; } int func2(void) { return 600; } int func3(void) { return 700; } Question The above code does not compile in gcc compiler whereas compiles in g++ (Assuming you make changes related to gcc in code like changing the code to .c not using any C++ header files... etc). The error displayed is "duplicate definition of inline function - func3". Can you clarify why this difference is present across compile? When you run the program (g++ compiled) by creating two seperate compilation unit (main.o and tran.o and create an executable a.out), the output obtained is 500 6 700 Why does the compiler pick up the definition of the function which is not inline. Actually since #include is used to "add" the inline definiton I had expected 5,6,7 as the output. My understanding was during compilation since the inline definition is found, the function call would be "replaced" by inline function definition. Can you please tell me in detailed steps the process of compilation and linking which would lead us to 500,6,700 output. I can only understand the output 6. Thanks in advance for valuable input.

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• Can I get a bitmap of an arbitrary window in another application process?

  - by Chris Farmer

  I am trying to automate a third-party Win32 application where I want to capture the graphics content of a particular window at defined time intervals. I am in the early phases of this, and I'm currently trying to use the Microsoft UI Automation API via C# to do most of the interaction between my client app and the external app. I can now get the external app to do what I want it to do, but now I want to capture the graphics from a specific window that seems to be some third-party owner-drawn control. How can I do this? The window I want to capture is the one marked by the red rectangle in this image: I have an implementation that sort of works, but it's dependent on the external app's UI being on top, and that's not guaranteed for me, so I'd prefer to find something more general. var p = Process.Start("c:\myapp.exe"); var mainForm = AutomationElement.FromHandle(p.MainWindowHandle); // "workspace" below is the window whose content I want to capture. var workspace = mainForm.FindFirst(TreeScope.Descendents, new PropertyCondition(AutomationElement.ClassNameProperty, "AfxFrameOrView70u")); var rect = (Rect) workspace.GetCurrentPropertyValue(AutomationElement.BoundingRectangleProperty); using (var bmp = new Bitmap((int)rect.Width, (int)rect.Height)) { using (var g = Graphics.FromImage(bmp)) { g.CopyFromScreen((int)rect.Left, (int)rect.Top, 0, 0, new Size((int)rect.Width, (int)rect.Height)); bmp.Save(@"c:\screenshot.png", ImageFormat.Png); } } The above works well enough when the automated app is on top, but it just blindly copies the screen in the rectangle, so my code is at the mercy of whatever happens to be running on the machine and might cover my app's window. I have read some suggestions to send the WM_PRINT message to the window. This question/answer from a few months back seemed promising, but when I use this code, I just get a white rectangle with none of my control's actual contents. var prop = (int)workspace.GetCurrentPropertyValue(AutomationElement.NativeWindowHandleProperty); var hwnd = new IntPtr(prop); using ( var bmp2 = new Bitmap((int)rect.Width, (int)rect.Height)) { using (Graphics g = Graphics.FromImage(bmp2)) { g.FillRectangle(SystemBrushes.Control, 0, 0, (int)rect.Width, (int)rect.Height); try { SendMessage(hwnd, WM_PRINT, g.GetHdc().ToInt32(), (int)(DrawingOptions.PRF_CHILDREN | DrawingOptions.PRF_CLIENT | DrawingOptions.PRF_OWNED)); } finally { g.ReleaseHdc(); } bmp2.Save(@"c:\screenshot.bmp"); } } So, first, is it even possible for me to reliably save a bitmap of a window's contents? If so, what is the best way, and what is wrong with my WM_PRINT with SendMessage attempt?

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• DriverManager always returns my custom driver regardless of the connection URL

  - by JGB146

  I am writing a driver to act as a wrapper around two separate MySQL connections (to distributed databases). Basically, the goal is to enable interaction with my driver for all applications instead of requiring the application to sort out which database holds the desired data. Most of the code for this is in place, but I'm having a problem in that when I attempt to create connections via the MySQL Driver, the DriverManager is returning an instance of my driver instead of the MySQL Driver. I'd appreciate any tips on what could be causing this and what could be done to fix it! Below is a few relevant snippets of code. I can provide more, but there's a lot, so I'd need to know what else you want to see. First, from MyDriver.java: public MyDriver() throws SQLException { DriverManager.registerDriver(this); } public Connection connect(String url, Properties info) throws SQLException { try { return new MyConnection(info); } catch (Exception e) { return null; } } public boolean acceptsURL(String url) throws SQLException { if (url.contains("jdbc:jgb://")) { return true; } return false; } It is my understanding that this acceptsURL function will dictate whether or not the DriverManager deems my driver a suitable fit for a given URL. Hence it should only be passing connections from my driver if the URL contains "jdbc:jgb://" right? Here's code from MyConnection.java: Connection c1 = null; Connection c2 = null; /** *Constructors */ public DDBSConnection (Properties info) throws SQLException, Exception { info.list(System.out); //included for testing Class.forName("com.mysql.jdbc.Driver").newInstance(); String url1 = "jdbc:mysql://server1.com/jgb"; String url2 = "jdbc:mysql://server2.com/jgb"; this.c1 = DriverManager.getConnection( url1, info.getProperty("username"), info.getProperty("password")); this.c2 = DriverManager.getConnection( url2, info.getProperty("username"), info.getProperty("password")); } And this tells me two things. First, the info.list() call confirms that the correct user and password are being sent. Second, because we enter an infinite loop, we see that the DriverManager is providing new instances of my connection as matches for the mysql URLs instead of the desired mysql driver/connection. FWIW, I have separately tested implementations that go straight to the mysql driver using this exact syntax (al beit only one at a time), and was able to successfully interact with each database individually from a test application outside of my driver.

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• How to deal with class composition when components cannot be accessed from the outside?

  - by Chathuranga

  For example if I say I have three classes A, B, and C where B and C have a composition relation ship with A. That means the life of B and C is handled by A, and also B and C cannot access directly from the outside. For some reason my DataService class needs to return objects of B and C as It cant return a object of A as B and C cannot be initialized at the same time. (to be able to initializeC you have to initializeB first). So that I'm returning DataTables from DataService and then inside the class A those data tables are converted to B / C objects. If B and C objects cannot be initialized at the same time is it valid to say that B and C have a composition relationship with A? If its composition is it must to generate A with B and C inside? What is the proper way to handle this sort of a problem? EDIT: Following code explains the way I'm doing it now with DataTables. Example: class A { private List<B> B; private List <C> C; public A() { B= new List<B>(); C= new List<C>(); } public List<B> GetB( DataTable dt) { // Create a B list from dt return B; } } class Presenter { private void Show B() { _View.DataGrid = A.GetB(DataService.GetAListOfB()); } } The actual scenario is I have a class called WageInfo and classes Earning and Deduction having a composition relationship in the design. But for you to generate Deductions first you should Generate earnings and should be saved in a table. Then only you can generate deductions for the earnings to calculate balance wages. Also note that these contained classes have a one to many relationship with the containing class WageInfo. So actually WageInfo has a List<Earnings> and List<Deduction> My initial question was, is it ok if my DataService class returns Deductions / Earnings objects (actually lists) not a WageInfo? Still not clear?

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• Mocking a concrete class : templates and avoiding conditional compilation

  - by AshirusNW

  I'm trying to testing a concrete object with this sort of structure. class Database { public: Database(Server server) : server_(server) {} int Query(const char* expression) { server_.Connect(); return server_.ExecuteQuery(); } private: Server server_; }; i.e. it has no virtual functions, let alone a well-defined interface. I want to a fake database which calls mock services for testing. Even worse, I want the same code to be either built against the real version or the fake so that the same testing code can both: Test the real Database implementation - for integration tests Test the fake implementation, which calls mock services To solve this, I'm using a templated fake, like this: #ifndef INTEGRATION_TESTS class FakeDatabase { public: FakeDatabase() : realDb_(mockServer_) {} int Query(const char* expression) { MOCK_EXPECT_CALL(mockServer_, Query, 3); return realDb_.Query(); } private: // in non-INTEGRATION_TESTS builds, Server is a mock Server with // extra testing methods that allows mocking Server mockServer_; Database realDb_; }; #endif template <class T> class TestDatabaseContainer { public: int Query(const char* expression) { int result = database_.Query(expression); std::cout << "LOG: " << result << endl; return result; } private: T database_; }; Edit: Note the fake Database must call the real Database (but with a mock Server). Now to switch between them I'm planning the following test framework: class DatabaseTests { public: #ifdef INTEGRATION_TESTS typedef TestDatabaseContainer<Database> TestDatabase ; #else typedef TestDatabaseContainer<FakeDatabase> TestDatabase ; #endif TestDatabase& GetDb() { return _testDatabase; } private: TestDatabase _testDatabase; }; class QueryTestCase : public DatabaseTests { public: void TestStep1() { ASSERT(GetDb().Query(static_cast<const char *>("")) == 3); return; } }; I'm not a big fan of that compile-time switching between the real and the fake. So, my question is: Whether there's a better way of switching between Database and FakeDatabase? For instance, is it possible to do it at runtime in a clean fashion? I like to avoid #ifdefs. Also, if anyone has a better way of making a fake class that mimics a concrete class, I'd appreciate it. I don't want to have templated code all over the actual test code (QueryTestCase class). Feel free to critique the code style itself, too. You can see a compiled version of this code on codepad.

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• how to refresh list of photos after uploadify jquery

  - by robert

  hello, I want to do a sort of photo editor, i use uploadify to upload images here are my files: http://www.mediafire.com/?nddjyzyygj5 the problem is: after upload the images i dinamicaly generate a thumb .. When I click on it it show me the large pictures in another page, i want to show the picture in a div or a paragraf! after I refresh the page is working! why? from my php script i recive only the image name (response) after UploadifyComplete i append this: jQuery("#" + jQuery(this).attr('id') + ID).html('<a href="uploads/' + response + '"><img width="60px" height="60px" src="uploads/' + response + '" alt="' + response + '" /></a>'); to this: jQuery(queue).append('<li class="uploadifyQueueItem">\ <span class="fileName">' + fileName + ' (' + byteSize + suffix + ')</span>\ <div class="uploadifyProgress">\ <div id="' + jQuery(this).attr('id') + ID + 'ProgressBar" class="uploadifyProgressBar"><!--Progress Bar--></div>\ </div>\ </li>'); } and the result will be: <div class="uploadifyQueue"> <ul id="mainftpQueue"> <li class="uploadifyQueueItem"> <a href="uploads/Winter.jpg"><img height="60px" width="60px" alt="Winter.jpg" src="uploads/Winter.jpg"></a> </li> </ul> </div> i putt all the images in 1 php array after all images uploaded i want to refresh the div where this code is: <div class="uploadifyQueue"> <?php if ($_SESSION['files']){ print '<ul id="mainftpQueue">'."\n"; foreach($_SESSION['files'] as $image ): print '<li class="uploadifyQueueItem">'."\n"; print '<a href="uploads/'.$image.'"><img height="60px" width="60px" alt="'.$image.'" src="uploads/'.$image.'"></a>'."\n"; print "</li>\n"; endforeach; print "</ul>\n"; } ?> </div> i try with: $('#mainftpQueue').load(location.href+" #mainftpQueue>*",""); $('#mainftpQueue').load("/ #mainftpQueue li"); buth no succes sorry 4 my bad english.. if any 1 can edit this thanks

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• Grouping geographical shapes

  - by grenade

  I am using Dundas Maps and attempting to draw a map of the world where countries are grouped into regions that are specific to a business implementation. I have shape data (points and segments) for each country in the world. I can combine countries into regions by adding all points and segments for countries within a region to a new region shape. foreach(var region in GetAllRegions()){ var regionShape = new Shape { Name = region.Name }; foreach(var country in GetCountriesInRegion(region.Id)){ var countryShape = GetCountryShape(country.Id); regionShape.AddSegments(countryShape.ShapeData.Points, countryShape.ShapeData.Segments); } map.Shapes.Add(regionShape); } The problem is that the country border lines still show up within a region and I want to remove them so that only regional borders show up. Dundas polygons must start and end at the same point. This is the case for all the country shapes. Now I need an algorithm that can: Determine where country borders intersect at a regional border, so that I can join the regional border segments. Determine which country borders are not regional borders so that I can discard them. Sort the resulting regional points so that they sequentialy describe the shape boundaries. Below is where I have gotten to so far with the map. You can see that the country borders still need to be removed. For example, the border between Mongolia and China should be discarded whereas the border between Mongolia and Russia should be retained. The reason I need to retain a regional border is that the region colors will be significant in conveying information but adjacent regions may be the same color. The regions can change to include or exclude countries and this is why the regional shaping must be dynamic. EDIT: I now know that I what I am looking for is a UNION of polygons. David Lean explains how to do it using the spatial functions in SQL Server 2008 which might be an option but my efforts have come to a halt because the resulting polygon union is so complex that SQL truncates it at 43,680 characters. I'm now trying to either find a workaround for that or find a way of doing the union in code.

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• What are the Options for Storing Hierarchical Data in a Relational Database?

  - by orangepips

  Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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• Windows 7 - pydoc from cmd

  - by Random_Person

  Okay, I'm having one of those moments that makes me question my ability to use a computer. This is not the sort of question I imagined asking as my first SO post, but here goes. Started on Zed's new "Learn Python the Hard Way" since I've been looking to get back into programming after a 10 year hiatus and python was always what I wanted. This book has really spoken to me. That being said, I'm having a serious issue with pydoc from the command. I've got all the directories in c:/python26 in my system path and I can execute pydoc from the command line just fine regardless of pwd - but it accepts no arguments. Doesn't matter what I type, I just get the standard pydoc output telling me the acceptable arguments. Any ideas? For what it's worth, I installed ActivePython as per Zed's suggestion. C:\Users\Chevee>pydoc file pydoc - the Python documentation tool pydoc.py <name> ... Show text documentation on something. <name> may be the name of a Python keyword, topic, function, module, or package, or a dotted reference to a class or function within a module or module in a package. If <name> contains a '\', it is used as the path to a Python source file to document. If name is 'keywords', 'topics', or 'modules', a listing of these things is displayed. pydoc.py -k <keyword> Search for a keyword in the synopsis lines of all available modules. pydoc.py -p <port> Start an HTTP server on the given port on the local machine. pydoc.py -g Pop up a graphical interface for finding and serving documentation. pydoc.py -w <name> ... Write out the HTML documentation for a module to a file in the current directory. If <name> contains a '\', it is treated as a filename; if it names a directory, documentation is written for all the contents. C:\Users\Chevee> EDIT: New information, pydoc works just fine in PowerShell. As a linux user, I have no idea why I'm trying to use cmd anyways--but I'd still love to figure out what's up with pydoc and cmd. EDIT 2: More new information. In cmd... c:\>python c:/python26/lib/pydoc.py file ...works just fine. Everything works just fine with just pydoc in PowerShell without me worrying about pwd, or extensions or paths.

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• How to check for palindrome using Python logic

  - by DrOnline

  My background is only a 6 month college class in basic C/C++, and I'm trying to convert to Python. I may be talking nonsense, but it seems to me C, at least at my level, is very for-loop intensive. I solve most problems with these loops. And it seems to me the biggest mistake people do when going from C to Python is trying to implement C logic using Python, which makes things run slowly, and it's just not making the most of the language. I see on this website: http://hyperpolyglot.org/scripting (serach for "c-style for", that Python doesn't have C-style for loops. Might be outdated, but I interpret it to mean Python has its own methods for this. I've tried looking around, I can't find much up to date (Python 3) advice for this. How can I solve a palindrome challenge in Python, without using the for loop? I've done this in C in class, but I want to do it in Python, on a personal basis. The problem is from the Euler Project, great site btw. def isPalindrome(n): lst = [int(n) for n in str(n)] l=len(lst) if l==0 || l==1: return True elif len(lst)%2==0: for k in range (l) ##### else: while (k<=((l-1)/2)): if (list[]): ##### for i in range (999, 100, -1): for j in range (999,100, -1): if isPalindrome(i*j): print(i*j) break I'm missing a lot of code here. The five hashes are just reminders for myself. Concrete questions: 1) In C, I would make a for loop comparing index 0 to index max, and then index 0+1 with max-1, until something something. How to best do this in Python? 2) My for loop (in in range (999, 100, -1), is this a bad way to do it in Python? 3) Does anybody have any good advice, or good websites or resources for people in my position? I'm not a programmer, I don't aspire to be one, I just want to learn enough so that when I write my bachelor's degree thesis (electrical engineering), I don't have to simultaneously LEARN an applicable programming language while trying to obtain good results in the project. "How to go from basic C to great application of Python", that sort of thing. 4) Any specific bits of code to make a great solution to this problem would also be appreciated, I need to learn good algorithms.. I am envisioning 3 situations. If the value is zero or single digit, if it is of odd length, and if it is of even length. I was planning to write for loops... PS: The problem is: Find the highest value product of two 3 digit integers that is also a palindrome.

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• Synchronizing thread communication?

  - by Roger Alsing

  Just for the heck of it I'm trying to emulate how JRuby generators work using threads in C#. Also, I'm fully aware that C# haas built in support for yield return, I'm just toying around a bit. I guess it's some sort of poor mans coroutines by keeping multiple callstacks alive using threads. (even though none of the callstacks should execute at the same time) The idea is like this: The consumer thread requests a value The worker thread provides a value and yields back to the consumer thread Repeat untill worker thread is done So, what would be the correct way of doing the following? //example class Program { static void Main(string[] args) { ThreadedEnumerator<string> enumerator = new ThreadedEnumerator<string>(); enumerator.Init(() => { for (int i = 1; i < 100; i++) { enumerator.Yield(i.ToString()); } }); foreach (var item in enumerator) { Console.WriteLine(item); }; Console.ReadLine(); } } //naive threaded enumerator public class ThreadedEnumerator<T> : IEnumerator<T>, IEnumerable<T> { private Thread enumeratorThread; private T current; private bool hasMore = true; private bool isStarted = false; AutoResetEvent enumeratorEvent = new AutoResetEvent(false); AutoResetEvent consumerEvent = new AutoResetEvent(false); public void Yield(T item) { //wait for consumer to request a value consumerEvent.WaitOne(); //assign the value current = item; //signal that we have yielded the requested enumeratorEvent.Set(); } public void Init(Action userAction) { Action WrappedAction = () => { userAction(); consumerEvent.WaitOne(); enumeratorEvent.Set(); hasMore = false; }; ThreadStart ts = new ThreadStart(WrappedAction); enumeratorThread = new Thread(ts); enumeratorThread.IsBackground = true; isStarted = false; } public T Current { get { return current; } } public void Dispose() { enumeratorThread.Abort(); } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { if (!isStarted) { isStarted = true; enumeratorThread.Start(); } //signal that we are ready to receive a value consumerEvent.Set(); //wait for the enumerator to yield enumeratorEvent.WaitOne(); return hasMore; } public void Reset() { throw new NotImplementedException(); } public IEnumerator<T> GetEnumerator() { return this; } System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return this; } } Ideas?

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• Python. How to iterate through a list of lists looking for a partial match

  - by Becca Millard

  I'm completely stuck on this, without even an idea about how to wrap my head around the logic of this. In the first half of the code, I have successfully generation a list of (thousands of) lists of players names and efficiency scores: eg name_order_list = [["Bob", "Farley", 12.345], ["Jack", "Donalds", 14.567], ["Jack", "Donalds", 13.421], ["Jack", "Donalds", 15.232],["Mike", "Patricks", 10.543]] What I'm trying to do, is come up with a way to make a list of lists of the average efficiency of each player. So in that example, Jack Donalds appears multiple times, so I'd want to recognize his name somehow and average out the efficiency scores. Then sort that new list by efficiency, rather than name. So then the outcome would be like: average_eff_list = [[12.345, "Bob", "Farley"], [14.407, "Jack", "Donalds"], [10.543, "Mike", "Patricks"]] Here's what I tried (it's kind of a mess, but should be readable): total_list = [] odd_lines = [name_order_list[i] for i in range(len(name_order_list)) if i % 2 == 0] even_lines = [name_order_list[i] for i in range(len(name_order_list)) if i % 2 == 1] i = 0 j = i-1 while i <= 10650: iteration = 2 total_eff = 0 while odd_lines[i][0:2] == even_lines[i][0:2]: if odd_lines[i][0:2] == even_lines[j][0:2]: if odd_lines[j][0:2] != even_lines[j][0:2]: total_eff = even_lines[j][2]/(iteration-1) iteration -= 1 #account fr the single (rather than dual) additional entry else: total_eff = total_eff if iteration == 2: total_eff = (odd_lines[i][2] + even_lines[i][2]) / iteration else: total_eff = ((total_eff * (iteration - 2)) + (odd_lines[i][2] + even_lines[i][2])) / iteration iteration += 2 i += 1 j += 1 if i > 10650: break else: if odd_lines[i][0:2] == even_lines[j][0:2]: if odd_lines[j][0:2] != even_lines[j][0:2]: total_eff = (odd_lines[i][2] + even_lines[j][2]) / iteration else: total_eff = ((total_eff * (iteration -2)) + odd_lines[i][2]) / (iteration - 1) if total_eff == 0: #there's no match at all total_odd = [odd_lines[i][2], odd_lines[i][0], odd_lines[i][1]] total_list.append(total_odd) if even_lines[i][0:2] != odd_lines[i+1][0:2]: total_even = [even_lines[i][2], even_lines[i][0], even_lines[i][1]] else: total = [total_eff, odd_lines[i][0], odd_lines[i][1]] total_list.append(total) i += 1 if i > 10650: break else: print(total_list) Now, this runs well enough (doesn't get stuck or print someone's name multiple times) but the efficiency values are off by a large amount, so I know that scores are getting missed somewhere. This is a problem with my logic, I think, so any help would be greatly appreciated. As would any advice about how to loop through that massive list in a smarter way, since I'm sure there is one... EIDT: for this exercise, I need to keep it all in a list format. I can make new lists, but no using dictionaries, classes, etc.

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• Django admin fails when using includes in urlpatterns

  - by zenWeasel

  I am trying to refactor out my application a little bit to keep it from getting too unwieldily. So I started to move some of the urlpatterns out to sub files as the documentation proposes. Besides that fact that it just doesn't seem to be working (the items are not being rerouted) but when I go to the admin, it says that 'urlpatterns has not been defined'. The urls.py I have at the root of my application is: if settings.ENABLE_SSL: urlpatterns = patterns('', (r'^checkout/orderform/onepage/(\w*)/$','checkout.views.one_page_orderform',{'SSL':True},'commerce.checkout.views.single_product_orderform'), ) else: urlpatterns = patterns('', (r'^checkout/orderform/onepage/(\w*)/$','commerce.checkout.views.single_product_orderform'), ) urlpatterns+= patterns('', (r'^$', 'alchemysites.views.route_to_home'), (r'^%s/' % settings.DAJAXICE_MEDIA_PREFIX, include('dajaxice.urls')), (r'^/checkout/', include('commerce.urls')), (r'^/offers',include('commerce.urls')), (r'^/order/',include('commerce.urls')), (r'^admin/', include(admin.site.urls)), (r'^accounts/login/$', login), (r'^accounts/logout/$', logout), (r'^(?P<path>.*)/$','alchemysites.views.get_path'), (r'^static/(?P<path>.*)$', 'django.views.static.serve', {'document_root':settings.MEDIA_ROOT}), The urls I have moved out so far are the checkout/offers/order which are all subapps of 'commerce' where the urls.py for the apps are so to be clear. /urls.py in questions (included here) /commerce/urls.py where the urls.py I want to include is: order_info = { 'queryset': Order.objects.all(), } urlpatterns+= patterns('', (r'^offers/$','offers.views.start_offers'), (r'^offers/([a-zA-Z0-9-]*)/order/(\d*)/add/([a-zA-Z0-9-]*)/(\w*)/next/([a-zA-Z0-9-)/$','offers.views.show_offer'), (r'^reports/orders/$', list_detail.object_list,order_info), ) and the applications offers lies under commerce. And so the additional problem is that admin will not work at all, so I'm thinking because I killed it somewhere with my includes. Things I have checked for: Is the urlpatterns variable accidentally getting reset somewhere (i.e. urlpatterns = patterns, instead of urlpatterns+= patterns) Are the patterns in commerce.urls valid (yes, when moved back to root they work). So from there I am stumped. I can move everything back into the root, but was trying to get a little decoupled, not just for theoretical reason but for some short terms ones. Lastly if I enter www.domainname/checkout/orderform/onepage/xxxjsd I get the correct page. However, entering www.domainname/checkout/ gets handled by the alchemysites.views.get_path. If not the answer (because this is pretty darn specific), then is there a good way for troubleshoot urls.py? It seems to just be trial and error. Seems there should be some sort of parser that will tell you what your urlpatterns will do.

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• jquery tablesorter problem in FF only - header row disappears after show-hide of rows

  - by dac

  When the page loads, all the records show. Sorting works great until show-hide is used to filter the rows so only some show. Then the header row--with the arrows for sorting--DISAPPEARS. The problem is only in Firefox. It works great in IE7 and IE8. I'm using jQuery 1.4.2 from google. Code for show-hide $(document).ready(function() { // show all the rows $("#org_status tr").show(); //find selected filter $("#filter_status a").click(function(evt) { evt.preventDefault(); $("#org_status tr").hide(); var id = $(this).attr('id'); $("." + id).show(); }); }); Here is the HTML: <!-- show-hide "buttons" --> <p id='filter_status'>Filter by status: <a href='#' id='All'>All</a> <a href='#' id='Active'>Active</a> <a href='#' id='Inactive'>Inactive</a> <a href='#' id='Pending'>Pending</a> </p> <!-- table to sort -> <table id='org_status' class='info_table tablesorter'> <thead> <tr> <th class='org-name-col'>Name</th> <th class='org-status-col'>Status</th> </tr> </thead> <tbody> <tr class='All Active'> <td><a href='admin/org_edit.php?org=29'>Foo Net</a></td> <td>Active</td>"; </tr> <tr class='All Inactive'> <td><a href='admin/org_edit.php?org=22'>Bar</a></td> <td>Active</td>"; </tr> <tr class='All Pending'> <td><a href='admin/org_edit.php?org=11'> Bar Foo Very Long Org Name Goes Here</a></td> <td>Active</td>"; </tr> </tbody> </table>

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• Foreign Key Relationships and "belongs to many"

  - by jan

  I have the following model: S belongs to T T has many S A,B,C,D,E (etc) have 1 T each, so the T should belong to each of A,B,C,D,E (etc) At first I set up my foreign keys so that in A, fk_a_t would be the foreign key on A.t to T(id), in B it'd be fk_b_t, etc. Everything looks fine in my UML (using MySQLWorkBench), but generating the yii models results in it thinking that T has many A,B,C,D (etc) which to me is the reverse. It sounds to me like either I need to have A_T, B_T, C_T (etc) tables, but this would be a pain as there are a lot of tables that have this relationship. I've also googled that the better way to do this would be some sort of behavior, such that A,B,C,D (etc) can behave as a T, but I'm not clear on exactly how to do this (I will continue to google more on this) What do you think is the better solution? UML: Here's the DDL (auto generated). Just pretend that there is more than 3 tables referencing T. -- ----------------------------------------------------- -- Table `mydb`.`T` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`T` ( `id` INT NOT NULL AUTO_INCREMENT , PRIMARY KEY (`id`) ) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`S` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`S` ( `id` INT NOT NULL AUTO_INCREMENT , `thing` VARCHAR(45) NULL , `t` INT NOT NULL , PRIMARY KEY (`id`) , INDEX `fk_S_T` (`id` ASC) , CONSTRAINT `fk_S_T` FOREIGN KEY (`id` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`A` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`A` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff` VARCHAR(45) NULL , `bar` VARCHAR(45) NULL , `foo` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`B` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`B` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff2` VARCHAR(45) NULL , `foobar` VARCHAR(45) NULL , `other` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`C` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`C` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff3` VARCHAR(45) NULL , `foobar2` VARCHAR(45) NULL , `other4` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB;

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• GAE Datastore: persisting referenced objects

  - by David

  Two "I'm sorries" to begin with: 1) I've looked for a solution (here, and elsewhere), and couldn't find the answer. 2) English is not my mother tongue, so I may have some typos and the sort - please ignore them. To the point: I am trying to persist Java objects to the GAE datastore. I am not sure as to how to persist object having ("non-trivial") referenced object. That is, assume I have the following. public class Father { String name; int age; Vector<Child> offsprings; //this is what I call "non-trivial" reference //ctor, getters, setters... } public class Child { String name; int age; Father father; //this is what I call "non-trivial" reference //ctor, getters, setters... } The name field is unique in each type domain, and is considered a Primary-Key. In order to persist the "trivial" (String, int) fields, all I need is to add the correct annotation. So far so good. However, I don't understand how should I persist the home-brewed (Child, Father) types referenced. Should I: Convert each such reference to hold the Primary-Key (a name String, in this example) instead of the "actual" object. So, Vector<Child> offsprings; becomes Vector<String> offspringsNames; ? If that is the case, how do I handle the object at run-time? Do I just query for the Primary-Key from Class.getName, to retrieve the refrenced objects? Convert each such reference to hold the actual Key provided to me by the Datastore upon the proper put() operation? So, Vector<Child> offsprings; becomes Vector<Key> offspringsHashKeys; ? I would very much appreciate all kinds of comments. I have read ALL the offical relevant GAE docs/example. Throughout, they always persist "trivial" references, natively supported by the Datastore (e.g. in the Guestbook example, only Strings, and Longs). Many thanks, David

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• Variable lenght arguments in log4cxx LOG4CXX_ macros

  - by Horacio

  I am using log4cxx in a big C++ project but I really don't like how log4cxx handles multiple variables when logging: LOG4CXX_DEBUG(logger, "test " << var1 << " and " << var3 " and .....) I prefer using printf like variable length arguments: LOG4CXX_DEBUG(logger, "test %d and %d", var1, var3) So I implemented this small wrapper on top of log4cxx #include <string.h> #include <stdio.h> #include <stdarg.h> #include <log4cxx/logger.h> #include "log4cxx/basicconfigurator.h" const char * log_format(const char *fmt, ...); #define MYLOG_TRACE(logger, fmt, ...) LOG4CXX_TRACE(logger, log_format(fmt, ## __VA_ARGS__)) #define MYLOG_DEBUG(logger, fmt, ...) LOG4CXX_DEBUG(logger, log_format(fmt, ## __VA_ARGS__)) #define MYLOG_INFO(logger, fmt, ...) LOG4CXX_INFO(logger, log_format(fmt, ## __VA_ARGS__)) #define MYLOG_WARN(logger, fmt, ...) LOG4CXX_WARN(logger, log_format(fmt, ## __VA_ARGS__)) #define MYLOG_ERROR(logger, fmt, ...) LOG4CXX_ERROR(logger, log_format(fmt, ## __VA_ARGS__)) #define MYLOG_FATAL(logger, fmt, ...) LOG4CXX_FATAL(logger, log_format(fmt, ## __VA_ARGS__)) static log4cxx::LoggerPtr logger(log4cxx::Logger::getRootLogger()); int main(int argc, char **argv) { log4cxx::BasicConfigurator::configure(); MYLOG_INFO(logger, "Start "); MYLOG_WARN(logger, log_format("In running this in %d threads safe?", 1000)); MYLOG_INFO(logger, "End "); return 0; } const char *log_format(const char *fmt, ...) { va_list va; static char formatted[1024]; va_start(va, fmt); vsprintf(formatted, 1024, fmt, va); va_end(va); return formatted; } And this works perfectly but I know using that static variable (formatted) can become problematic if I start using threads and each thread logging to the same place. I am no expert in log4cxx so I was wondering if the LOG4CXX macros are handling concurrent thread access automatically? or do I have to implement some sort of locking around the log_format method? something that I wan't to avoid due to performance implications. Also I would like to ask why if I replace the vsprintf inside the log_format method with vsnprintf (that is more secure) then I get nothing printed? To compile and test this program (in Ubuntu) use : g++ -o loggertest loggertest.cpp -llog4cxx

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• Can you help me optimize this code for finding factors of a number? I'm brushing up on my math progr

  - by Sergio Tapia

  I've never really bothered with math programming, but today I've decided to give it a shot. Here's my code and it's working as intended: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; namespace PrimeFactorization { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void btnSubmit_Click(object sender, RoutedEventArgs e) { List<int> primeFactors = FindPrimeFactors(Convert.ToInt32(txtNumber.Text)); primeFactors.Sort(); for (int i = 0; i < primeFactors.Count; i++) { listBoxFoundNumbers.Items.Add(primeFactors[i]); } } private List<int> FindPrimeFactors(int number) { List<int> factors = new List<int>(); factors.Add(1); factors.Add(number); for (int i = 2; i < number; i++) { if (number % i == 0) { int holder = number / i; //If the number is in the list, don't add it again. if (!factors.Contains(i)) { factors.Add(i); } //If the number is in the list, don't add it again. if (!factors.Contains(holder)) { factors.Add(holder); } } } return factors; } } } The only problem I can see with my code is that it will iterate through to the bitter end, even though there will definitely not be any factors. For example, imagine I wrote in 35. My loop will go up to 35 and check 24,25,26,27...etc. Not very good. What do you recommend?

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• How to set and get the id for the items in the spinner in Android

  - by Haresh Chaudhary

  I have a problem in my project that i am displaying a activity which would contain the details of the project which is previously added in Project Management System.. Now the fields in it are like: Fields of the Activity Name Of Project: ABC(EditText) Name Of Developer : ________(Spinner) Deadline : ________(Date Picker) Created On : _______(TextView) . . Now, the Spinner contains the Names of all developers working in the Company..I have used the ArrayAdapter with a array having the names of all the developers which is fetched from the database.. The problem is that when i update the Name Of Developer field, i get Only the Name of the Developer which is not enough to update the data as their can be multiple developers with the same name in the Company..So now I require the id of the developers to update it.. How to store that id of the developers with the Spinner so that i can achieve this.. Please help me to sort this out. Actually what i want to do like is as that we do in html:: <select> <option id="1">Developer1</option> <option id="2">Developer2</option> <option id="3">Developer2</option> <option id="4">Developer2</option> </select> where the id attached would be the database id....I want to imitate this in our android.... This the code that i have used to store the names in the array:: String alldevelopers = null; try { ArrayList<NameValuePair> postP = new ArrayList<NameValuePair>(); alldevelopers = CustomHttpClient.executeHttpPost( "/fetchdevelopers.php", postP); String respcl = alldevelopers.toString(); alldevelopersParser dev = new alldevelopersParser(); ow = dev.parseByDOM(respcl); } catch (Exception e) { e.printStackTrace(); } String developers[] = new String[ow.length]; //dev is a class object for (int n = 0; n < ow.length; n++) { developers[n] = ow.developer[n][2]; } This is the Spinner that would spin the array.. final Spinner devl = (Spinner) findViewById(R.id.towner); devl.setOnItemSelectedListener(managetasks.this); ArrayAdapter<String> b = new ArrayAdapter<String>getApplicationContext(), android.R.layout.simple_spinner_item,developers); b.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line); devl.setAdapter(b);

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• How to get the top keys from a hash by value

  - by Kirs Kringle

  I have a hash that I sorted by values greatest to least. How would I go about getting the top 5? There was a post on here that talked about getting only one value. What is the easiest way to get a key with the highest value from a hash in Perl? I understand that so would lets say getting those values add them to an array and delete the element in the hash and then do the process again? Seems like there should be an easier way to do this then that though. My hash is called %words. use strict; use warnings; use Tk; #Learn to install here: http://factscruncher.blogspot.com/2012/01/easy-way-to-install-tk- on-strawberry.html #Reading in the text file my $file0 = Tk::MainWindow->new->Tk::getOpenFile; open( my $filehandle0, '<', $file0 ) || die "Could not open $file0\n"; my @words; while ( my $line = <$filehandle0> ) { chomp $line; my @word = split( /\s+/, lc($line)); push( @words, @word ); } for (@words) { s/[\,|\.|\!|\?|\:|\;|\"]//g; } #Counting words that repeat; put in hash my %words_count; $words_count{$_}++ for @words; #Reading in the stopwords file my $file1 = "stoplist.txt"; open( my $filehandle1, '<', $file1 ) or die "Could not open $file1\n"; my @stopwords; while ( my $line = <$filehandle1> ) { chomp $line; my @linearray = split( " ", $line ); push( @stopwords, @linearray ); } for my $w ( my @stopwords ) { s/\b\Q$w\E\B//ig; } #Comparing the array to Hash and deleteing stopwords my %words = %words_count; for my $stopwords ( @stopwords ) { delete $words{ $stopwords }; } #Sorting Hash Table my @keys = sort { $words{$b} <=> $words{$a} or "\L$a" cmp "\L$b" } keys %words; #Starting Statistical Work my $value_count = 0; my $key_count = 0; #Printing Hash Table $key_count = keys %words; foreach my $key (@keys) { $value_count = $words{$key} + $value_count; printf "%-20s %6d\n", $key, $words{$key}; } my $value_average = $value_count / $key_count; #my @topwords; #foreach my $key (@keys){ #if($words{$key} > $value_average){ # @topwords = keys %words; # } #} print "\n", "The number of values: ", $value_count, "\n"; print "The number of elements: ", $key_count, "\n"; print "The Average: ", $value_average, "\n\n";

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• How can I pass managed objects from one AppDomain to another?

  - by Dennis P

  I have two assemblies that I'm trying to link together. One is a sort of background process that's built with WinForms and will be designed to run as a Windows Service. I have a second project that will act as a UI for the background process whenever a user launches it. I've never tried attempting something like this with managed code before, so I've started trying to use windows messages to communicate between the two processes. I'm struggling when it comes to passing more than just IntPtrs back and forth, however. Here's the code from a control in my UI project that registers itself with the background process: public void Init() { IntPtr hwnd = IntPtr.Zero; Process[] ps = Process.GetProcessesByName("BGServiceApp"); Process mainProcess = null; if(ps == null || ps.GetLength(0) == 0) { mainProcess = LaunchApp(); } else { mainProcess = ps[0]; } SendMessage(mainProcess.MainWindowHandle, INIT_CONNECTION, this.Handle, IntPtr.Zero); } protected override void WndProc(ref Message m) { if(m.Msg == INIT_CONFIRMED && InitComplete != null) { string message = Marshal.PtrToStringAuto(m.WParam); Marshal.FreeHGlobal(m.WParam); InitComplete(message, EventArgs.Empty); } base.WndProc(ref m); } This is the code from the background process that's supposed to receive a request from the UI process to register for status updates and send a confirmation message. protected override void WndProc(ref Message m) { if(m.Msg == INIT_CONNECTION) { RegisterUIDispatcher(m.WParam); Respond(m.WParam); } if(m.Msg == UNINIT_CONNECTION) { UnregisterUIDispatcher(m.WParam); if(m_RegisteredDispatchers.Count == 0) { this.Close(); } } base.WndProc(ref m); } private void Respond(IntPtr caller) { string test = "Registration confirmed!"; IntPtr ptr = Marshal.StringToHGlobalAuto(test); SendMessage(caller, INIT_CONFIRMED, ptr, IntPtr.Zero); } } The UI process receives the INIT_CONFIRMED message from my background process, but when I try to marshal the IntPtr back into a string, I get an empty string. Is the area of heap I'm using out of scope to the other process or am I missing some security attribute maybe? Is there a better and cleaner way to go about something like this using an event driven model?

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• ASP.NET MVC 4/Web API Single Page App for Mobile Devices ... Needs Authentication

  - by lmttag

  We have developed an ASP.NET MVC 4/Web API single page, mobile website (also using jQuery Mobile) that is intended to be accessed only from mobile devices (e.g., iPads, iPhones, Android tables and phones, etc.), not desktop browsers. This mobile website will be hosted internally, like an intranet site. However, since we’re accessing it from mobile devices, we can’t use Windows authentication. We still need to know which user (and their role) is logging in to the mobile website app. We tried simply using ASP.NET’s forms authentication and membership provider, but couldn’t get it working exactly the way we wanted. What we need is for the user to be prompted for a user name and password only on the first time they access the site on their mobile device. After they enter a correct user name and password and have been authenticated once, each subsequent time they access the site they should just go right in. They shouldn’t have to re-enter their credentials (i.e., something needs to be saved locally to each device to identify the user after the first time). This is where we had troubles. Everything worked as expected the first time. That is, the user was prompted to enter a user name and password, and, after doing that, was authenticated and allowed into the site. The problem is every time after the browser was closed on the mobile device, the device and user were not know and the user had to re-enter user name and password. We tried lots of things too. We tried setting persistent cookies in JavaScript. No good. The cookies weren’t there to be read the second time. We tried manually setting persistent cookies from ASP.NET. No good. We, of course, used FormsAuthentication.SetAuthCookie(model.UserName, true); as part of the form authentication framework. No good. We tried using HTML5 local storage. No good. No matter what we tried, if the user was on a mobile device, they would have to log in every single time. (Note: we’ve tried on an iPad and iPhone running both iOS 5.1 and 6.0, with Safari configure to allow cookies, and we’ve tried on Android 2.3.4.) Is there some trick to getting a scenario like this working? Or, do we have to write some sort of custom authentication mechanism? If so, how? And, what? Or, should we use something like claims-based authentication and WIF? Or??? Any help is appreciated. Thanks!

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• Should I add try/catch around when casting on an attribute of JSP implicit object?

  - by Michael Mao

  Hi all: Basically what I mean is like this: List<String[]> routes = (List<String[]>)application.getAttribute("routes"); For the above code, it tries to get an attribute named "routes" from the JSP implicit object - application. But as everyone knows, after this line of code, routes may very well contains a null - which means this application hasn't got an attribute named "routes". Is this "casting on null" good programming practice in Java or not? Basically I try to avoid exceptions such as java.io.InvalidCastException I reckon things like this are more as "heritage" of Java 1.4 when generic types were not introduced to this language. So I guess everything stored in application attributes as Objects (Similar to traditional ArrayList). And when you do "downcast", there might be invalid casts. What would you do in this case? Update: Just found that although in the implicit object application I did store a List of String arrays, when I do this : List<double[]> routes = (List<double[]>)application.getAttribute("routes"); It doesn't produce any error... And I felt not comfortable already... And even with this code: out.print(routes.get(0)); It does print out something strange : [Ljava.lang.String;@18b352f Am I printing a "pointer to String"? I can finally get an exception like this: out.print(routes.get(0)[1]); with error : java.lang.ClassCastException: [Ljava.lang.String; Because it was me to add the application attribute, I know which type should it be cast to. I feel this is not "good enough", what if I forget the exact type? I know there are still some cases where this sort of thing would happen, such as in JSP/Servlet when you do casting on session attributes. Is there a better way to do this? Before you say:"OMG, why you don't use Servlets???", I should justify my reason as this: - because my uni sucks, its server can only work with Servlets generated by JSP, and I don't really want to learn how to fix issues like that. look at my previous question on this , and this is uni homework, so I've got no other choice, forget all about war, WEB-INF,etc, but "code everything directly into JSP" - because the professors do that too. :)

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• Why does extend() engage in bizarre behaviour when passed the same list twice?

  - by intuited

  I'm pretty confused by one of the subtleties of the vimscript extend() function. If you use it to extend a list with another list, it does pretty much what you'd expect, which is to insert the second list into the first list at the index given by the third parameter: let list1 = [1,2,3,4,5,6] | echo extend(list1,[1,2,3,4,5,6],5) " [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 6, 6] However if you give it the same list twice it starts tripping out a bit. let list1 = [1,2,3,4,5,6] | echo extend(list1,list1,0) " [1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6] let list1 = [1,2,3,4,5,6] | echo extend(list1,list1,1) " [1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6] let list1 = [1,2,3,4,5,6] | echo extend(list1,list1,2) " [1, 2, 1, 2, 1, 2, 1, 2, 3, 4, 5, 6] let list1 = [1,2,3,4,5,6] | echo extend(list1,list1,3) " [1, 2, 3, 1, 2, 3, 1, 2, 3, 4, 5, 6] let list1 = [1,2,3,4,5,6] | echo extend(list1,list1,4) " [1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 5, 6] let list1 = [1,2,3,4,5,6] | echo extend(list1,list1,5) " [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 6] let list1 = [1,2,3,4,5,6] | echo extend(list1,list1,6) " [1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6] Extra-confusingly, this behaviour applies when the list is referenced with two different variables: let list1 = [1,2,3,4,5,6] | let list2 = list1 | echo extend(list1,list2,4) " [1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 5, 6] This is totally bizarre to me. I can't fathom a use for this functionality, and it seems like it would be really easy to invoke it by accident when you just wanted to insert one list into another and didn't realize that the variables were referencing the same array. The documentation says the following: If they are |Lists|: Append {expr2} to {expr1}. If {expr3} is given insert the items of {expr2} before item {expr3} in {expr1}. When {expr3} is zero insert before the first item. When {expr3} is equal to len({expr1}) then {expr2} is appended. Examples: :echo sort(extend(mylist, [7, 5])) :call extend(mylist, [2, 3], 1) When {expr1} is the same List as {expr2} then the number of items copied is equal to the original length of the List. E.g., when {expr3} is 1 you get N new copies of the first item (where N is the original length of the List). Does this make sense in a way that I'm not getting, or is it just an eccentricity?

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