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• what is the correct way to force existing activities to reload using the new local

  - by pengwang

  have a settings dialog/activity where I allow the user to change the locale. Within that activity i call Resources res = ctx.getResources(); // Change locale settings on the device DisplayMetrics dm = res.getDisplayMetrics(); android.content.res.Configuration conf = res.getConfiguration(); conf.locale = new Locale(language_code.toLowerCase(), coutry_code.toUpperCase()); res.updateConfiguration(conf, dm); and call onChanged() for my settings ListView... everything changes perfectly. Very nice. Then I hit the back button to go back to the previous activity thinking everything should be switched; nope. Everything is still in the previous locale. So I added the above code in the onResume() of the activity thinking that would do it; nope. Also, when I click the menu button of this activity again (not first time) I do not get called in onCreateOptionsMenu() it just displays the previous menu. My question is what is the correct way to force existing activities to reload using the new local?

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• Queueing method calls - any idea how?

  - by TomTom

  I write a heavily asynchronseous application. I am looking for a way to queue method calls, similar to what BeginInvoke / EndInvoke does.... but on my OWN queue. The reaqson is that I am having my own optimized message queueing system using a threadpool but at the same time making sure every component is single threaded in the requests (i.e. one thread only handles messages for a component). I Have a lot of messages going back and forth. For limited use, I would really love to be able to just queue a message call with parameters, instead of having to define my own parameter, method wrapping / unwrapping just for the sake of doing a lot of admnistrative calls. I also do not always want to bypass the queue, and I definitely do not want the sending service to wait for the other service to respond. Anyone knows of a way to intercept a method call? Some way to utilize TransparentProxy / Virtual Proxy for this? ;) ServicedComponent? I would like this to be as little overhead as possible ;)

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• What's the "proper" way to retrieve a reference to a ribbon object?

  - by Nick

  For a VSTO workbook project, is there a best practice for retrieving a reference to the Ribbon object from the ThisWorkbook class? Here's what I'm doing: In my Ribbon class, I created a public method called InvalidateControl(string controlID). I need to call that method from the ThisWorkbook class based on when a certain workbook level event fires. But the only way I can see to "get" a reference to that Ribbon object is to do this... // This is all in the ThisWorkbook class Ribbon ribbon; protected override IRibbonExtensibility CreateRibbonExtensibilityObject() { this.ribbon = new Ribbon(); return this.ribbon; } ...which seems a little smelly. I mean, I have to override CreateRibbonExtensibilityObject() regardless; all I'm doing beyond that is maintaining a local reference to the ribbon so I can call methods against it. But it doesn't feel right. Is there another, better way to get that reference in the ThisWorkbook class? Or is this pretty acceptable? Thanks!

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• How to properly handle signals when using the worker thread pattern?

  - by ipartola

  I have a simple server that looks something like this: void *run_thread(void *arg) { // Communicate via a blocking socket } int main() { // Initialization happens here... // Main event loop while (1) { new_client = accept(socket, ...); pthread_create(&thread, NULL, &run_thread, *thread_data*); pthread_detach(thread); } // Do cleanup stuff: close(socket); // Wait for existing threads to finish exit(0); ) Thus when a SIGINT or SIGTERM is received I need to break out of the main event loop to get to the clean up code. Moreover most likely the master thread is waiting on the accept() call so it's not able to check some other variable to see if it should break;. Most of the advice I found was along the lines of this: http://devcry.blogspot.com/2009/05/pthreads-and-unix-signals.html (creating a special signal handling thread to catch all the signals and do processing on those). However, it's the processing portion that I can't really wrap my head around: how can I possibly tell the main thread to return from the accept() call and check on an external variable to see if it should break;?

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• LicenseChecker checkAccess leaks ServiceConnection

  - by Bill The Ape

  I am receiving this exception in LogCat every time I press the Back button in my app: Activity has leaked ServiceConnection com.android.vending.licensing.LicenseChecker@471cc039 that was originally bound here The code responsible for this leak in onCreate() is: mLicenseCheckerCallback = new MyLicenseCheckerCallback(); mChecker.checkAccess(mLicenseCheckerCallback); How do I get rid of this leak? I tried not assigning MyLicenseCheckerCallback to a member, thinking perhaps when the activity goes onPause() the reference to the callback is responsible for the leak: mChecker.checkAccess(new MyLicenseCheckerCallback()); But that didn't get rid of the leak. Update: Thanks to @zapl's comment below, I looked at Google's LicenseChecker.java: /** Unbinds service if necessary and removes reference to it. */ private void cleanupService() { if (mService != null) { try { mContext.unbindService(this); } catch (IllegalArgumentException e) { // Somehow we've already been unbound. This is a non-fatal error. Log.e(TAG, "Unable to unbind from licensing service (already unbound)"); } mService = null; } } At first I thought that I may be neglecting to call it, but I double-checked and I am calling mChecker.onDestroy(); in my activity's onDestroy(). I also checked onDestroy() in LicenseChecker.java and it is calling unbindService: /** * Inform the library that the context is about to be destroyed, so that * any open connections can be cleaned up. * <p> * Failure to call this method can result in a crash under certain * circumstances, such as during screen rotation if an Activity requests * the license check or when the user exits the application. */ public synchronized void onDestroy() { cleanupService(); mHandler.getLooper().quit(); } So, what is really going on? Is this a bug in LVL?

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• Accurately and securely measure the time spent viewing a web page

  - by balpha

  Suppose the following: You have a web page that presents a simple game to a user (e.g. a quiz, a puzzle, etc). The user solves the puzzle, submits the result, and you want to measure as precisely as possible how long they took to solve it. Assume it's quite simple, so we're talking seconds, not hours. Also assume JavaScript is required anyway, so there's no need to think of JS-disabled browsers. Finally, assume we don't want to use anything like Flash, Silverlight, or the like. I can think of several techniques: Simply take the time between the points when the data was sent from the server and when the submission arrives. Since this is exclusively server-side, there's no chance for cheating. However, issues like network latency and page rendering time might make this unfair for users with slow computers / browsers / internet connections. On the first request, just send the page without the actual game data. When everything is loaded so far, retrieve the game data through an AJAX call and populate it into the page. This is similar to 1., but reduces some of the caveats introduced through time spent on overhead. Have the time measured on the client side using JavaScript and submitted alongside with the solution. This would theoretically be the most accurate, but it introduces the possibility of cheating, because you're relying on client data. Use the request time headers of a "ready to play" AJAX call and the result submission request. Same caveat as 3., as it is still client data. A combination of server side and client side measuring with some kind of plausibility analysis. I can't think of a good way, but maybe you can. Thoughts? Other ideas?

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• Ruby on Rails controller and architecture with cells

  - by dt

  I decided to try to use the cells plugin from rails: http://cells.rubyforge.org/community.html given that I'm new to Ruby and very used to thinking in terms of components. Since I'm developing the app piecemeal and then putting it together piece by piece, it makes sense to think in terms of components. So, I've been able to get cells working properly inside a single view, which calls a partial. Now, what I would like to be able to do (however, maybe my instincts need to be redirected to be more "Rails-y"), is call a single cell controller and use the parameters to render one output vs. another. Basically, if there were a controller like: def index params[:responsetype] end def processListResponse end def processSearchResponse end And I have two different controller methods that I want to respond to based on the params response type, where I have a single template on the front end and want the inner "component" to render differently depending on what type of request is made. That allows me to reuse the same front-end code. I suppose I could do this with an ajax call instead and just have it rerender the component on the front end, but it would be nice to have the option to do it either way and to understand how to architect Rails a bit better in the process. It seems like there should be a "render" option from within the cells framework to render to a certain controller or view, but it's not working like I expect and I don't know if I'm even in the ballpark. Thanks!

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• Am I doing AS3 reference cleanup correctly?

  - by Ólafur Waage

  In one frame of my fla file (let's call it frame 2), I load a few xml files, then send that data into a class that is initialized in that frame, this class creates a few timers and listeners. Then when this class is done doing it's work. I call a dispatchEvent and move to frame 3. This frame does some things as well, it's initialized and creates a few event listeners and timers. When it's done, I move to frame 2 again. This is supposed to repeat as often as I need so I need to clean up the references correctly and I'm wondering if I'm doing it correctly. For sprites I do this. world.removeChild(Background); // world is the parent stage Background = null; For instances of other classes I do this. Players[i].cleanUp(world); // do any cleanup within the instanced class world.removeChild(PlayersSelect[i]); For event listeners I do this. if(Background != null) { Background.removeEventListener(MouseEvent.CLICK, deSelectPlayer); } For timers I do this. if(Timeout != null) { Timeout.stop(); Timeout.removeEventListener(TimerEvent.TIMER, queueHandler); Timeout.removeEventListener(TimerEvent.TIMER_COMPLETE, queueCompleted); Timeout = null; } And for library images I do this if(_libImage!= null) { s.removeChild(Images._libImage); // s is the stage _libImage= null; } And for the class itself in the main timeline, I do this Frame2.removeEventListener("Done", IAmDone); Frame2.cleanUp(); // the cleanup() does all the stuff above Frame2= null; Even if I do all this, when I get to frame 2 for the 2nd time, it runs for 1-2 seconds and then I get a lot of null reference errors because the cleanup function is called prematurely. Am I doing the cleanup correctly? What can cause events to fire prematurely?

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• Compiler turning a string& into a basic_string<>&

  - by Shtong

  Hello I'm coming back to C++ after long years spent on other technologies and i'm stuck on some weird behavior when calling some methods taking std::string as parameters : An example of call : LocalNodeConfiguration *LocalNodeConfiguration::ReadFromFile(std::string & path) { // ... throw configuration_file_error(string("Configuration file empty"), path); // ... } When I compile I get this (I cropped file names for readability) : /usr/bin/g++ -g -I/home/shtong/Dev/OmegaNoc/build -I/usr/share/include/boost-1.41.0 -o CMakeFiles/OmegaNocInternals.dir/configuration/localNodeConfiguration.cxx.o -c /home/shtong/Dev/OmegaNoc/source/configuration/localNodeConfiguration.cxx .../localNodeConfiguration.cxx: In static member function ‘static OmegaNoc::LocalNodeConfiguration* OmegaNoc::LocalNodeConfiguration::ReadFromFile(std::string&)’: .../localNodeConfiguration.cxx:72: error: no matching function for call to ‘OmegaNoc::configuration_file_error::configuration_file_error(std::string, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)’ .../configurationManager.hxx:25: note: candidates are: OmegaNoc::configuration_file_error::configuration_file_error(std::string&, std::string&) .../configurationManager.hxx:22: note: OmegaNoc::configuration_file_error::configuration_file_error(const OmegaNoc::configuration_file_error&) So as I understand it, the compiler is considering that my path parameter turned into a basic_string at some point, thus not finding the constructor overload I want to use. But I don't really get why this transformation happened. Some search on the net suggested me to use g++ but I was already using it. So any other advice would be appreciated :) Thanks

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• How to catch unintentional function interpositioning?

  - by SiegeX

  Reading through my book Expert C Programming, I came across the chapter on function interpositioning and how it can lead to some serious hard to find bugs if done unintentionally. The example given in the book is the following: my_source.c mktemp() { ... } main() { mktemp(); getwd(); } libc mktemp(){ ... } getwd(){ ...; mktemp(); ... } According to the book, what happens in main() is that mktemp() (a standard C library function) is interposed by the implementation in my_source.c. Although having main() call my implementation of mktemp() is intended behavior, having getwd() (another C library function) also call my implementation of mktemp() is not. Apparently, this example was a real life bug that existed in SunOS 4.0.3's version of lpr. The book goes on to explain the fix was to add the keyword static to the definition of mktemp() in my_source.c; although changing the name altogether should have fixed this problem as well. This chapter leaves me with some unresolved questions that I hope you guys could answer: Does GCC have a way to warn about function interposition? We certainly don't ever intend on this happening and I'd like to know about it if it does. Should our software group adopt the practice of putting the keyword static in front of all functions that we don't want to be exposed? Can interposition happen with functions introduced by static libraries? Thanks for the help. EDIT I should note that my question is not just aimed at interposing over standard C library functions, but also functions contained in other libraries, perhaps 3rd party, perhaps ones created in-house. Essentially, I want to catch any instance of interpositioning regardless of where the interposed function resides.

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• ajaxStart() showing loading message doesn't seem to work....

  - by Pandiya Chendur

  I user jquery.ajax call to controller of asp.net mvc... I would like to show a loading indicator.. I tried this but that doesn't seem to work... <div class="loading" style="padding-left:5px; margin-bottom:5px;display:none;"> Loading...&nbsp </div> and my jquery ajax call looks like this, function getMaterials(currentPage) { $.ajax({ url: "Materials/GetMaterials", data: {'currentPage': (currentPage + 1) ,'pageSize':5}, contentType: "application/json; charset=utf-8", global: false, async: false, dataType: "json", success: function(data) { var divs = ''; $("#ResultsDiv").empty(); $.each(data.Results, function() { //my logic here.... $(".loading").bind("ajaxStart", function() { $(this).show(); }).bind("ajaxStop", function() { $(this).hide(); }); } }); return false; } My loading indicator doen't seem to showup.. ANy suggestion....

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• Import CSV to class structure as the user defines

  - by Assimilater

  I have a contact manager program and I would like to offer the feature to import csv files. The problem is that different data sources order the fields in different ways. I thought of programming an interface for the user to tell it the field order and how to handle exceptions. Here is an example line in one of many possible field orders: "ID#","Name","Rank","Address1","Address2","City","State","Country","Zip","Phone#","Email","Join Date","Sponsor ID","Sponsor Name" "Z1234","Call, Anson","STU","1234 E. 6578 S.","","Somecity","TX","United States","012345","000-000-0000","[email protected]","5/24/2010","z12343","Quantum Independence" Notice that in one data field "Name" there is a comma to separate last name and first name and in another there is not. My plan is to have a line for each field (ie ID, Name, City etc.) and a statement "import to" and list box with options like: Don't Import, BusinessJoin Date, First Name, Zip and the program recognizes those as properties of an object... I'd also like the user to be able to record preset field orders so they can re-use them for csv files from the same download source. Then I also need it to check if a record all ready exists (is there a record for Anson Call all ready?) and allow the user to tell it what to do if there is a record (ie mailing address may have changes, so if that field is filled overwrite it, or this mailing address is invalid, leave the current data untouched for this person, overwrite the rest). While I'm capable of coding this...i'm not very excited about it and I'm wondering if there's a tool or set of tools out there to all ready perform most of this functionality... I hope this makes sense...

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• Jquery Ajax + PHP

  - by Kris.Mitchell

  I am having problems with jQuery Ajax and PHP I have my php file set up to echo the data I am gathering from a mysql database. I have verified that the database is returning something and that the string at the end of the function actually contains data. What is happening though, is that it looks like the php echo is happening before the ajax call, causing the php data to be displayed at the top of the page, and not below in proper div. I think it might have something to do with timing of the ajax and the php call, but I am not sure. So, why is the data not getting caught by the .ajax and thrown into the div? Thanks for the help! jQuery $(document).ready(function() { $.ajax({ url: "../database_functions.php", type: "GET", data: "cat=jw&sub=pi&sort=no", cache: false, success: function (html) { alert("Success!"); $('#product-list').html(html); } }); }); PHP echo "Hello World";

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• tk: how to invoke it just to display something, and return to the main program?

  - by max

  Sorry for the noob question but I really don't understand this. I'm using python / tkinter and I want to display something (say, a canvas with a few shapes on it), and keep it displayed until the program quits. I understand that no widgets would be displayed until I call tkinter.tk.mainloop(). However, if I call tkinter.tk.mainloop(), I won't be able to do anything else until the user closes the main window. I don't need to monitor any user input events, just display some stuff. What's a good way to do this without giving up control to mainloop? EDIT: Is this sample code reasonable: class App(tk.Tk): def __init__(self, sim): self.sim = sim # link to the simulation instance self.loop() def loop(): self.redraw() # update all the GUI to reflect new simulation state sim.next_step() # advance simulation another step self.after(0, self.loop) def redraw(): # get whatever we need from self.sim, and put it on the screen EDIT2 (added after_idle): class App(tk.Tk): def __init__(self, sim): self.sim = sim # link to the simulation instance self.after_idle(self.preloop) def preloop(): self.after(0, self.loop) def loop(): self.redraw() # update all the GUI to reflect new simulation state sim.next_step() # advance simulation another step self.after_idle(self.preloop) def redraw(): # get whatever we need from self.sim, and put it on the screen

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• Getting empty update rectangle in OnPaint after calling InvalidateRect on a layered window

  - by Shawn

  I'm trying to figure out why I've been getting an empty update rectangle when I call InvalidateRect on a transparent window. The idea is that I've drawn something on the window (it gets temporarily switched to have an alpha of 1/255 for the drawing), and then I switch it to full transparent mode (i.e. alpha of 0) in order to interact with the desktop & to be able to move the drawing around the screen on top of the desktop. When I try to move the drawing, I get its bounding rectangle & use it to call InvalidateRect, as such: InvalidateRect(m_hTarget, &winRect, FALSE); I've confirmed that the winRect is indeed correct, and that m_hTarget is the correct window & that its rectangle fully encompasses winRect. I get into the OnPaint handler in the class corresponding to m_hTarget, which is derived from a CWnd. In there, I create a CPaintDC, but when I try to access the update rectangle (dcPaint.m_ps.rcPaint) it's always empty. This rectangle gets passed to a function that determines if we need to update the screen (by using UpdateLayeredWindow in the case of a transparent window). If I hard-code a non-empty rectangle in here, the remaining code works correctly & I am able to move the drawing around the screen. I tried changing the 'FALSE' parameter to 'TRUE' in InvalidateRect, with no effect. I also tried using a standard CDC, and then using BeginPaint/EndPaint method in my OnPaint handler, just to ensure that CPaintDC wasn't doing something odd ... but I got the same results. The code that I'm using was originally designed for opaque windows. If m_hTarget corresponds to an opaque window, the same set of function calls results in the correct (i.e. non-empty) rectangle being passed to OnPaint. Once the window is layered, though, it doesn't seem to work right.

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• Stored Procedure: Reducing Table Data

  - by SumGuy

  Hi Guys, A simple question about Stored Procedures. I have one stored procedure collecting a whole bunch of data in a table. I then call this procedure from within another stored procedure. I can copy the data into a new table created in the calling procedure but as far as I can see the tables have to be identical. Is this right? Or is there a way to insert only the data I want? For example.... I have one procedure which returns this: SELECT @batch as Batch, @Count as Qty, pd.Location, cast(pd.GL as decimal(10,3)) as [Length], cast(pd.GW as decimal(10,3)) as Width, cast(pd.GT as decimal(10,3)) as Thickness FROM propertydata pd GROUP BY pd.Location, pd.GL, pd.GW, pd.GT I then call this procedure but only want the following data: DECLARE @BatchTable TABLE ( Batch varchar(50), [Length] decimal(10,3), Width decimal(10,3), Thickness decimal(10,3), ) INSERT @BatchTable (Batch, [Length], Width, Thickness) EXEC dbo.batch_drawings_NEW @batch So in the second command I don't want the Qty and Location values. However the code above keeps returning the error: "Insert Error: Column name or number of supplied values does not match table"

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• Exceptional C++[Bug]?

  - by gautam kumar

  I have been reading Exceptional C++ by Herb Sutter. On reaching Item 32 I found the following namespace A { struct X; struct Y; void f( int ); void g( X ); } namespace B { void f( int i ) { f( i ); // which f()? } } This f() calls itself, with infinite recursion. The reason is that the only visible f() is B::f() itself. There is another function with signature f(int), namely the one in namespace A. If B had written "using namespace A;" or "using A::f;", then A::f(int) would have been visible as a candidate when looking up f(int), and the f(i) call would have been ambiguous between A::f(int) and B::f(int). Since B did not bring A::f(int) into scope, however, only B::f(int) can be considered, so the call unambiguously resolves to B::f(int). But when I did the following.. namespace A { struct X; struct Y; void f( int ); void g( X ); } namespace B { using namespace A; void f( int i ) { f( i ); // No error, why? } } That means Herb Sutter has got it all wrong? If not why dont I get an error?

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• Process a set of files from a source directory to a destination directory in Python

  - by Spoike

  Being completely new in python I'm trying to run a command over a set of files in python. The command requires both source and destination file (I'm actually using imagemagick convert as in the example below). I can supply both source and destination directories, however I can't figure out how to easily retain the directory structure from the source to the destination directory. E.g. say the srcdir contains the following: srcdir/ file1 file3 dir1/ file1 file2 Then I want the program to create the following destination files on destdir: destdir/file1, destdir/file3, destdir/dir1/file1 and destdir/dir1/file2 So far this is what I came up with: import os from subprocess import call srcdir = os.curdir # just use the current directory destdir = 'path/to/destination' for root, dirs, files in os.walk(srcdir): for filename in files: sourceFile = os.path.join(root, filename) destFile = '???' cmd = "convert %s -resize 50%% %s" % (sourceFile, destFile) call(cmd, shell=True) The walk method doesn't directly provide what directory the file is under srcdir other than concatenating the root directory string with the file name. Is there some easy way to get the destination file, or do I have to do some string manipulation in order to do this?

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• unexpected behaviour of object stored in web service Session

  - by draconis

  Hi. I'm using Session variables inside a web service to maintain state between successive method calls by an external application called QBWC. I set this up by decorating my web service methods with this attribute: [WebMethod(EnableSession = true)] I'm using the Session variable to store an instance of a custom object called QueueManager. The QueueManager has a property called ChangeQueue which looks like this: [Serializable] public class QueueManager { ... public Queue<QBChange> ChangeQueue { get; set; } ... where QBChange is a custom business object belonging to my web service. Now, every time I get a call to a method in my web service, I use this code to retrieve my QueueManager object and access my queue: QueueManager qm = (QueueManager)Session[ticket]; then I remove an object from the queue, using qm.dequeue() and then I save the modified query manager object (modified because it contains one less object in the queue) back to the Session variable, like so: Session[ticket] = qm; ready for the next web service method call using the same ticket. Now here's the thing: if I comment out this last line //Session[ticket] = qm; , then the web service behaves exactly the same way, reducing the size of the queue between method calls. Now why is that? The web service seems to be updating a class contained in serialized form in a Session variable without being asked to. Why would it do that? When I deserialize my Queuemanager object, does the qm variable hold a reference to the serialized object inside the Session[ticket] variable?? This seems very unlikely.

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• Is locking on the requested object a bad idea?

  - by Quick Joe Smith

  Most advice on thread safety involves some variation of the following pattern: public class Thing { private static readonly object padlock = new object(); private string stuff, andNonsense; public string Stuff { get { lock (Thing.padlock) { if (this.stuff == null) this.stuff = "Threadsafe!"; } return this.stuff; } } public string AndNonsense { get { lock (Thing.padlock) { if (this.andNonsense == null) this.andNonsense = "Also threadsafe!"; } return this.andNonsense; } } // Rest of class... } In cases where the get operations are expensive and unrelated, a single locking object is unsuitable because a call to Stuff would block all calls to AndNonsense, degrading performance. And rather than create a lock object for each call, wouldn't it be better to acquire the lock on the member itself (assuming it is not something that implements SyncRoot or somesuch for that purpose? For example: public string Stuff { get { lock (this.stuff) { // Pretend that this is a very expensive operation. if (this.stuff == null) this.stuff = "Still threadsafe and good?"; } return this.stuff; } } Strangely, I have never seen this approach recommended or warned against. Am I missing something obvious?

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• Should a C++ constructor do real work?

  - by Wade Williams

  I'm strugging with some advice I have in the back of my mind but for which I can't remember the reasoning. I seem to remember at some point reading some advice (can't remember the source) that C++ constructors should not do real work. Rather, they should initialize variables only. The advice when on to explain that real work should be done in some sort of init() method, to be called separately after the instance was created. The situation is I have a class that represents a hardware device. It makes logical sense to me for the constructor to call the routines that query the device in order to build up the instance variables that describe the device. In other words, once new instantiates the object, the developer receives an object which is ready to be used, no separate call to object-init() required. Is there a good reason why constructors shouldn't do real work? Obviously it could slow allocation time, but that wouldn't be any different if calling a separate method immediately after allocation. Just trying to figure out what gotchas I not currently considering that might have lead to such advice.

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• PHP Check slave status without mysql_connect timeout issues

  - by Jonathon

  I have a web-app that has a master mysql db and four slave dbs. I want to handle all (or almost all) read-only (SELECT) queries from the slaves. Our load-balancer sends the user to one of the slave machines automatically, since they are also running Apache/PHP and serving webpages. I am using an include file to setup the connection to the databases, such as: //for master server (i.e. - UPDATE/INSERT/DELETE statements) $Host = "10.0.0.x"; $User = "xx"; $Password = "xx"; $Link = mysql_connect( $Host, $User, $Password ); if( !$Link ) ) { die( "Master database is currently unavailable. Please try again later." ); } //this connection can be used for READ-ONLY (i.e. - SELECT statements) on the localhost $Host_Local = "localhost"; $User_Local = "xx"; $Password_Local = "xx"; $Link_Local = mysql_connect( $Host_Local, $User_Local, $Password_Local ); //fail back to master if slave db is down if( !$Link_Local ) ) { $Link_Local = mysql_connect( $Host, $User, $Password ); } I then use $Link for all update queries and $Link_Local as the connection for SELECT statements. Everything works fine until the slave server database goes down. If the local db is down, the $Link_Local = mysql_connect() call takes at least 30 seconds before it gives up on trying to connect to the localhost and returns back to the script. This causes a huge backlog of page serves and basically shuts down the system (due to the extremely slow response time). Does anyone know of a better way to handle connections to slave servers via PHP? Or, is there some kind of timeout function that could be used to stop the mysql_connect call after 2-3 seconds? Thanks for the help. I searched the other mysql_connect threads, but didn't see any that addressed this issue.

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• Code Contracts: Do we have to specify Contract.Requires(...) statements redundantly in delegating me

  - by herzmeister der welten

  I'm intending to use the new .NET 4 Code Contracts feature for future development. This made me wonder if we have to specify equivalent Contract.Requires(...) statements redundantly in a chain of methods. I think a code example is worth a thousand words: public bool CrushGodzilla(string weapon, int velocity) { Contract.Requires(weapon != null); // long code return false; } public bool CrushGodzilla(string weapon) { Contract.Requires(weapon != null); // specify contract requirement here // as well??? return this.CrushGodzilla(weapon, int.MaxValue); } For runtime checking it doesn't matter much, as we will eventually always hit the requirement check, and we will get an error if it fails. However, is it considered bad practice when we don't specify the contract requirement here in the second overload again? Also, there will be the feature of compile time checking, and possibly also design time checking of code contracts. It seems it's not yet available for C# in Visual Studio 2010, but I think there are some languages like Spec# that already do. These engines will probably give us hints when we write code to call such a method and our argument currently can or will be null. So I wonder if these engines will always analyze a call stack until they find a method with a contract that is currently not satisfied? Furthermore, here I learned about the difference between Contract.Requires(...) and Contract.Assume(...). I suppose that difference is also to consider in the context of this question then?

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• Java reflection appropriateness

  - by jsn

  This may be a fairly subjective question, but maybe not. My application contains a bunch of forms that are displayed to the user at different times. Each form is a class of its own. Typically the user clicks a button, which launches a new form. I have a convenience function that builds these buttons, you call it like this: buildButton( "button text", new SelectionAdapter() { @Override public void widgetSelected( SelectionEvent e ) { showForm( new TasksForm( args... ) ); } } ); I do this dozens of times, and it's really cumbersome having to make a SelectionAdapter every time. Really all I need for the button to know is what class to instantiate when it's clicked and what arguments to give the constructor, so I built a function that I call like this instead: buildButton( "button text", TasksForm.class, args... ); Where args is an arbitrary list of objects that you could use to instantiate TasksForm normally. It uses reflection to get a constructor from the class, match the argument list, and build an instance when it needs to. Most of the time I don't have to pass any arguments to the constructor at all. The downside is obviously that if I'm passing a bad set of arguments, it can't detect that at compilation time, so if it fails, a dialog is displayed at runtime. But it won't normally fail, and it'll be easy to debug if it does. I think this is much cleaner because I come from languages where the use of function and class literals is pretty common. But if you're a normal Java programmer, would seeing this freak you out, or would you appreciate not having to scan a zillion SelectionAdapters?

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• Memory Leak in returning NSMutableArray from class

  - by Structurer

  Hi I am quite new to Objective C for the iPhone, so I hope you wont kill me for asking a simple question. I have made an App that works fine, except that Instruments reports memory leaks from the class below. I use it to store settings from one class and then retrieve them from another class. These settings are stored on a file so they can be retrieved every time the App is ran. What can I do do release the "setting" and is there anything that can be done to call (use) the class in a smarter way? Thanks ----- Below is Settings.m ----- import "Settings.h" @implementation Settings @synthesize settings; -(NSString *)dataFilePath // Return path for settingfile, including filename { NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; return [documentsDirectory stringByAppendingPathComponent:kUserSettingsFileName]; } -(NSMutableArray *)getParameters // Return settings from disk after checking if file exist (if not create with default values) { NSString *filePath = [self dataFilePath]; if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) // Getting data from file { settings = [[NSMutableArray alloc] initWithContentsOfFile:filePath]; } else // Creating default settings { settings = [[NSMutableArray alloc] initWithObjects: [NSNumber numberWithInteger:50], [NSNumber numberWithInteger:50], nil]; [settings writeToFile:[self dataFilePath] atomically:YES]; } return settings; } ----- Below is my other class from where I call my Settings class ----- // Get settings from file Settings *aSetting = [[Settings alloc] init]; mySettings = [aSetting getParameters]; [aSetting release];

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