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• How do I serialise a graph in Java without getting StackOverflowException?

  - by Tim Cooper

  I have a graph structure in java, ("graph" as in "edges and nodes") and I'm attempting to serialise it. However, I get "StackOverflowException", despite significantly increasing the JVM stack size. I did some googling, and apparently this is a well known limitation of java serialisation: that it doesn't work for deeply nested object graphs such as long linked lists - it uses a stack record for each link in the chain, and it doesn't do anything clever such as a breadth-first traversal, and therefore you very quickly get a stack overflow. The recommended solution is to customise the serialisation code by overriding readObject() and writeObject(), however this seems a little complex to me. (It may or may not be relevant, but I'm storing a bunch of fields on each edge in the graph so I have a class JuNode which contains a member ArrayList<JuEdge> links;, i.e. there are 2 classes involved, rather than plain object references from one node to another. It shouldn't matter for the purposes of the question). My question is threefold: (a) why don't the implementors of Java rectify this limitation or are they already working on it? (I can't believe I'm the first person to ever want to serialise a graph in java) (b) is there a better way? Is there some drop-in alternative to the default serialisation classes that does it in a cleverer way? (c) if my best option is to get my hands dirty with low-level code, does someone have an example of graph serialisation java source-code that can use to learn how to do it?

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• Is there anything bad in declaring static inner class inside interface in java?

  - by Roman

  I have an interface ProductService with method findByCriteria. This method had a long list of nullable parameters, like productName, maxCost, minCost, producer and so on. I refactored this method by introducing Parameter Object. I created class SearchCriteria and now method signature looks like this: findByCriteria (SearchCriteria criteria) I thought that instances of SearchCriteria are only created by method callers and are only used inside findByCriteria method, i.e.: void processRequest() { SearchCriteria criteria = new SearchCriteria () .withMaxCost (maxCost) ....... .withProducer (producer); List<Product> products = productService.findByCriteria (criteria); .... } and List<Product> findByCriteria(SearchCriteria criteria) { return doSmthAndReturnResult(criteria.getMaxCost(), criteria.getProducer()); } So I did not want to create separate public class for SearchCriteria and put it inside ProductServiceInterface: public interface ProductService { List<Product> findByCriteria (SearchCriteria criteria); static class SearchCriteria { ... } } Is there anything bad in this interface? Where whould you place SearchCriteria class?

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• How to display a busy message over a wpf screen

  - by dave

  Hey, I have a WPF application based on Prism4. When performing slow operations, I want to show a busy screen. I will have a large number of screens, so I'm trying to build a single solution into the framework rather than adding the busy indicator to each screen. These long running operations run in a background thread. This allows the UI to be updated (good) but does not stop the user from using the UI (bad). What I'd like to do is overlay a control with a spinning dial sort of thing and have that control cover the entire screen (the old HTML trick with DIVs). When the app is busy, the control would display thus block any further interaction as well as showing the spinny thing. To set this up, I thought I could just have my app screen in a canvas along with the spinny thing (with a greater ZIndex) then just make the spinny thing visible as required. This, however, is getting hard. Canvases do not seem well set up for this and I think I might be barking up the wrong tree. I would appreciate any help. Thanks.

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• GPS not update location after close and reopen app on android

  - by mrmamon

  After I closed my app for a while then reopen it again,my app will not update location or sometime it will take long time( about 5min) before update. How can I fix it? This is my code private LocationManager lm; private LocationListener locationListener; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); locationListener = new mLocationListener(); lm.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 0, locationListener); } private class myLocationListener implements LocationListener { @Override public void onLocationChanged(Location loc) { if (loc != null) { TextView gpsloc = (TextView) findViewById(R.id.widget28); gpsloc.setText("Lat:"+loc.getLatitude()+" Lng:"+ loc.getLongitude()); } } @Override public void onProviderDisabled(String provider) { // TODO Auto-generated method stub TextView gpsloc = (TextView) findViewById(R.id.widget28); gpsloc.setText("GPS OFFLINE."); } @Override public void onProviderEnabled(String provider) { // TODO Auto-generated method stub } @Override public void onStatusChanged(String provider, int status, Bundle extras) { // TODO Auto-generated method stub } }

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• Move camera to fit 3D scene

  - by Burre

  Hi there. I'm looking for an algorithm to fit a bounding box inside a viewport (in my case a DirectX scene). I know about algorithms for centering a bounding sphere in a orthographic camera but would need the same for a bounding box and a perspective camera. I have most of the data: I have the up-vector for the camera I have the center point of the bounding box I have the look-at vector (direction and distance) from the camera point to the box center I have projected the points on a plane perpendicular to the camera and retrieved the coefficients describing how much the max/min X and Y coords are within or outside the viewing plane. Problems I have: Center of the bounding box isn't necessarily in the center of the viewport (that is, it's bounding rectangle after projection). Since the field of view "skew" the projection (see http://en.wikipedia.org/wiki/File:Perspective-foreshortening.svg) I cannot simply use the coefficients as a scale factor to move the camera because it will overshoot/undershoot the desired camera position How do I find the camera position so that it fills the viewport as pixel perfect as possible (exception being if the aspect ratio is far from 1.0, it only needs to fill one of the screen axis)? I've tried some other things: Using a bounding sphere and Tangent to find a scale factor to move the camera. This doesn't work well, because, it doesn't take into account the perspective projection, and secondly spheres are bad bounding volumes for my use because I have a lot of flat and long geometries. Iterating calls to the function to get a smaller and smaller error in the camera position. This has worked somewhat, but I can sometimes run into weird edge cases where the camera position overshoots too much and the error factor increases. Also, when doing this I didn't recenter the model based on the position of the bounding rectangle. I couldn't find a solid, robust way to do that reliably. Help please!

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• Processing velocity-vectors during collision as neatly as possible

  - by DevEight

  Hello. I'm trying to create a good way to handle all possible collisions between two objects. Typically one will be moving and hitting the other, and should then "bounce" away. What I've done so far (I'm creating a typical game where you have a board and bounce a ball at bricks) is to check if the rectangles intersect and if they do, invert the Y-velocity. This is a really ugly and temporary solution that won't work in the long haul and since this is kind of processing is very common in games I'd really like to find a great way of doing this for future projects aswell. Any links or helpful info is appreciated. Below is what my collision-handling function looks like right now. protected void collision() { #region Boundaries if (bal.position.X + bal.velocity.X >= viewportRect.Width || bal.position.X + bal.velocity.X <= 0) { bal.velocity.X *= -1; } if (bal.position.Y + bal.velocity.Y <= 0) { bal.velocity.Y *= -1; } #endregion bal.rect = new Rectangle((int)bal.position.X+(int)bal.velocity.X-bal.sprite.Width/2, (int)bal.position.Y-bal.sprite.Height/2+(int)bal.velocity.Y, bal.sprite.Width, bal.sprite.Height); player.rect = new Rectangle((int)player.position.X-player.sprite.Width/2, (int)player.position.Y-player.sprite.Height/2, player.sprite.Width, player.sprite.Height); if (bal.rect.Intersects(player.rect)) { bal.position.Y = player.position.Y - player.sprite.Height / 2 - bal.sprite.Height / 2; if (player.position.X != player.prevPos.X) { bal.velocity.X -= (player.prevPos.X - player.position.X) / 2; } bal.velocity.Y *= -1; } foreach (Brick b in brickArray.list) { b.rect.X = Convert.ToInt32(b.position.X-b.sprite.Width/2); b.rect.Y = Convert.ToInt32(b.position.Y-b.sprite.Height/2); if (bal.rect.Intersects(b.rect)) { b.recieveHit(); bal.velocity.Y *= -1; } } brickArray.removeDead(); }

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• Auditing front end performance on web application

  - by user1018494

  I am currently trying to performance tune the UI of a company web application. The application is only ever going to be accessed by staff, so the speed of the connection between the server and client will always be considerably more than if it was on the internet. I have been using performance auditing tools such as Y Slow! and Google Chrome's profiling tool to try and highlight areas that are worth targeting for investigation. However, these tools are written with the internet in mind. For example, the current suggestions from a Google Chrome audit of the application suggests is as follows: Network Utilization Combine external CSS (Red warning) Combine external JavaScript (Red warning) Enable gzip compression (Red warning) Leverage browser caching (Red warning) Leverage proxy caching (Amber warning) Minimise cookie size (Amber warning) Parallelize downloads across hostnames (Amber warning) Serve static content from a cookieless domain (Amber warning) Web Page Performance Remove unused CSS rules (Amber warning) Use normal CSS property names instead of vendor-prefixed ones (Amber warning) Are any of these bits of advice totally redundant given the connection speed and usage pattern? The users will be using the application frequently throughout the day, so it doesn't matter if the initial hit is large (when they first visit the page and build their cache) so long as a minimal amount of work is done on future page views. For example, is it worth the effort of combining all of our CSS and JavaScript files? It may speed up the initial page view, but how much of a difference will it really make on subsequent page views throughout the working day? I've tried searching for this but all I keep coming up with is the standard internet facing performance advice. Any advice on what to focus my performance tweaking efforts on in this scenario, or other auditing tool recommendations, would be much appreciated.

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• How to find out where a thread lock happend?

  - by SchlaWiener

  One of our company's Windows Forms application had a strange problem for several month. The app worked very reliable for most of our customers but on some PC's (mostly with a wireless lan connection) the app sometimes just didn't respond anymore. (You click on the UI and windows ask you to wait or kill the app). I wasn't able to track down the problem for a long time but now I figured out what happend. The app had this line of code // don't blame me for this. Wasn't my code :D Control.CheckForIllegalCrossThreadCalls = false and used some background threads to modify the controls. No I found a way to reproduce the application stopping responding bug on my dev machine and tracked it down to a line where I actually used Invoke() to run a task in the main thread. Me.Invoke(MyDelegate, arg1, arg2) Obviously there was a thread lock somewhere. After removing the Control.CheckForIllegalCrossThreadCalls = false statement and refactoring the whole programm to use Invoke() if modifying a control from a background thread, the problem is (hopefully) gone. However, I am wondering if there is a way to find such bugs without debugging every line of code (Even if I break into debugger after the app stops responding I can't tell what happend last, because the IDE didn't jump to the Invoke() statement) In other words: If my apps hangs how can I figure out which line of code has been executed last? Maybe even on the customers PC. I know VS2010 offers some backwards debugging feature, maybe that would be a solution, but currently I am using VS2008.

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• Codeigniter/mySQL question. Checking if several inserts are possible before actual insertion.

  - by Ethan

  Hey SO, So I'm trying to perform a couple inserts at once that are kind of co-dependent on each other. Let's say I'm doing a dog rating website. Anyone can add a dog to my database, but in doing so they also need to add a preliminary rating of the dog. Other people can then rate the dog afterwards. The dogs to ratings is a many to one relationship: a dog has many ratings. This means for my preliminary add, since I have the person both rate and add the dog, I need to take the rating, and set a foreign key to the dog's primary key. As far as I know, this means I have to actually add the dog, then check what that new addition's primary key is, and then put that in my rating before insertion. Now suppose something were to go wrong with the rating's insert, be it a string that's too long, or something that I've overlooked somehow. If the rating's failed, the dog has already been inserted, but the rating has not. In this case, I'd like the dog to not have been added in the first place. Does this mean I have to write code that says "if the rating fails, do a remove for the dog," or is there a way to predict what the key will be for the dog should everything go as planned. Is there a way to say "hold that spot," and then if everything works, add it? Any help would be greatly appreciated. Thanks!!

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• Android ArrayList<Location> passing between activities

  - by squixy

  I have simple class Track, which stores information about route: import java.io.Serializable; import java.util.ArrayList; import java.util.Date; import android.location.Location; public class Track implements Serializable { private static final long serialVersionUID = -5317697499269650204L; private Date date; private String name; private int time; private double distance, speed; private ArrayList<Location> route; public Track(String name, int time, double distance, ArrayList<Location> route) { this.date = new Date(); this.name = name; this.time = time; this.distance = distance; this.speed = distance / (time / 3600.); this.route = route; } public String getDate() { return String.format("Date: %1$td-%1$tb-%1$tY%nTime: %1$tH:%1$tM:%1$tS", date); } public String getName() { return name; } public int getTime() { return time; } public double getDistance() { return distance; } public float getSpeed() { return (float) speed; } public ArrayList<Location> getRoute() { return route; } @Override public String toString() { return String.format("Name: %s%nDate: %2$td-%2$tb-%2$tY%nTime: %2$tH:%2$tM:%2$tS", name, date); } } And I'm passing it from one activity to another: Intent showTrackIntent = new Intent(TabSavedActivity.this, ShowTrackActivity.class); showTrackIntent.putExtra("track", adapter.getItem(position)); startActivity(showTrackIntent); Where (Track object is element on ListView). I get error during passing Track object: java.lang.RuntimeException: Parcelable encountered IOException writing serializable object (name = classes.Track) What is happening?

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• Is this a bug? Or is it a setting in ASP.NET 4 (or MVC 2)?

  - by John Gietzen

  I just recently started trying out T4MVC and I like the idea of eliminating magic strings. However, when trying to use it on my master page for my stylesheets, I get this: <link href="<%: Links.Content.site_css %>" rel="stylesheet" type="text/css" /> rending like this: <link href="&lt;%: Links.Content.site_css %>" rel="stylesheet" type="text/css" /> Whereas these render correctly: <link href="<%: Url.Content("~/Content/Site.css") %>" rel="stylesheet" type="text/css" /> <link href="<%: Links.Content.site_css + "" %>" rel="stylesheet" type="text/css" /> It appears that, as long as I have double quotes inside of the code segment, it works. But when I put anything else in there, it escapes the leading "less than". Is this something I can turn off? Is this a bug? Edit: This does not happen for <script src="..." ... />, nor does it happen for <a href="...">. Edit 2: Minimal case: <link href="<%: string.Empty %>" /> vs <link href="<%: "" %>" />

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• java.lang.IllegalArgumentException: View not attached to window manager

  - by alex2k8

  I have an activity that starts AsyncTask and shows progress dialog for the duration of operation. The activity is declared NOT be recreated by rotation or keyboard slide. <activity android:name=".MyActivity" android:label="@string/app_name" android:configChanges="keyboardHidden|orientation" > <intent-filter> </intent-filter> </activity> Once task completed, I dissmiss dialog, but on some phones (framework: 1.5, 1.6) such error is thrown: java.lang.IllegalArgumentException: View not attached to window manager at android.view.WindowManagerImpl.findViewLocked(WindowManagerImpl.java:356) at android.view.WindowManagerImpl.removeView(WindowManagerImpl.java:201) at android.view.Window$LocalWindowManager.removeView(Window.java:400) at android.app.Dialog.dismissDialog(Dialog.java:268) at android.app.Dialog.access$000(Dialog.java:69) at android.app.Dialog$1.run(Dialog.java:103) at android.app.Dialog.dismiss(Dialog.java:252) at xxx.onPostExecute(xxx$1.java:xxx) My code is: final Dialog dialog = new AlertDialog.Builder(context) .setTitle("Processing...") .setCancelable(true) .create(); final AsyncTask<MyParams, Object, MyResult> task = new AsyncTask<MyParams, Object, MyResult>() { @Override protected MyResult doInBackground(MyParams... params) { // Long operation goes here } @Override protected void onPostExecute(MyResult result) { dialog.dismiss(); onCompletion(result); } }; task.execute(...); dialog.setOnCancelListener(new OnCancelListener() { @Override public void onCancel(DialogInterface arg0) { task.cancel(false); } }); dialog.show(); From what I have read (http://bend-ing.blogspot.com/2008/11/properly-handle-progress-dialog-in.html) and seen in Android sources, it looks like the only possible situation to get that exception is when activity was destroyed. But as I have mentioned, I forbid activity recreation for basic events. So any suggestions are very appreciated.

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• Is there a best practice for concatenating MP3 Files, adjusting sample rates to match, while preserving original files?

  - by Scott

  Hello overflow community! Does anyone know if there is a "best practice" to concatenate mp3 files to create new files, while preserving the original files? I am working on a CentOS Linux machine, in command line. I will eventually call the command line from a PHP script. I have been doing research and I have come up with a process that I think could work. It combines general advice from different forums, blogs, and sources like this one. So here I go: Create a temporary folder Loop through files to create a new, converted copy, of file into a "raw" format (which one, I don't know. I didn't know "raw" files existed before too long ago. I could use some suggestions on this) Store the path to the temporary files, in the temporary folder, and then loop through the files to concatenate them and then put the new merged file the final "processed directory" Delete the contents of the temporary file with the temporary raw files inside. Convert the final file from "raw" to mp3 and enjoy the finished result I'm thinking that this course of action might be best because I can't necessarily control the quality of the original "source" mp3s. The only other option I could think of would be to create a script that would perform a similar process upon files being added to the system leaving only the files with the "proper" format and removing the original "erroneous" file. Hopefully you can see that I have put some thought into this and that I'm trying to leverage the collective knowledge of this community to choose the best direction. Perhaps there is a better path that I could take? By concatenate, I mean to join together in sequence to create a new audio file from the "concatenated files."

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• How to get spacing between characters printed using TextOut ?

  - by life-warrior

  I'm trying to calcuate size of each cell (containing text like "ff" or "a0"), so that 32 cells will fit into window by width. However, charWidth*2 doesn' represent the width of a cell, since it doesn't take spacing between characters in the account. How can I obtain size of a font so that 32 cells each is two chars like "ff" fit exactly into window's client area ? Curier is fixed-width font. RECT rect; ::GetClientRect( hWnd, &rect ); LONG charWidth = (rect.right-rect.left)/BLOCK_SIZE/2-2; int oldMapMode = ::SetMapMode( hdc, MM_TEXT ); HFONT font = CreateFont( charWidth*2, charWidth, 0, 0, FW_DONTCARE, FALSE, FALSE, FALSE, DEFAULT_CHARSET, OUT_OUTLINE_PRECIS, CLIP_DEFAULT_PRECIS, CLEARTYPE_QUALITY, FF_ROMAN, _T("Courier") ); HGDIOBJ oldFont = ::SelectObject( hdc, font ); for( int i = 0; i < BLOCK_SIZE; ++i ) { CString str; str.Format( _T("%.2x"), (unsigned char)*(g_memAddr+i) ); SIZE size; ::TextOut( hdc, (size.cx+2)*i+1, 1, str, _tcslen((LPCTSTR)str) ); }

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• Need a better way to execute console commands from python and log the results

  - by Wim Coenen

  I have a python script which needs to execute several command line utilities. The stdout output is sometimes used for further processing. In all cases, I want to log the results and raise an exception if an error is detected. I use the following function to achieve this: def execute(cmd, logsink): logsink.log("executing: %s\n" % cmd) popen_obj = subprocess.Popen(\ cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE) (stdout, stderr) = popen_obj.communicate() returncode = popen_obj.returncode if (returncode <> 0): logsink.log(" RETURN CODE: %s\n" % str(returncode)) if (len(stdout.strip()) > 0): logsink.log(" STDOUT:\n%s\n" % stdout) if (len(stderr.strip()) > 0): logsink.log(" STDERR:\n%s\n" % stderr) if (returncode <> 0): raise Exception, "execute failed with error output:\n%s" % stderr return stdout "logsink" can be any python object with a log method. I typically use this to forward the logging data to a specific file, or echo it to the console, or both, or something else... This works pretty good, except for three problems where I need more fine-grained control than the communicate() method provides: stdout and stderr output can be interleaved on the console, but the above function logs them separately. This can complicate the interpretation of the log. How do I log stdout and stderr lines interleaved, in the same order as they were output? The above function will only log the command output once the command has completed. This complicates diagnosis of issues when commands get stuck in an infinite loop or take a very long time for some other reason. How do I get the log in real-time, while the command is still executing? If the logs are large, it can get hard to interpret which command generated which output. Is there a way to prefix each line with something (e.g. the first word of the cmd string followed by :).

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• How to read a parameter passed to a facelet from a backing bean

  - by Antonio

  Hi, I've written a facelet, and a corresponding backing bean, that implements user management (addition, deletion and so on). I'd want to be able to perform some custom processing when, for instance, a new user is added. There is a "create" button in the facelet, whose click event is handled by its backing bean. At the end of the event handler, I'd want to be able to call a method of another backing bean, which is not known because ideally the facelet can be used in several pages, with different custom processing. I thought to implement this feature by providing to the facelet a backing bean name and a method name, like this: <myfacelet:subaccounts backingBean="myBackingBean" createListener="createListener" /> and at the end of the event handler call #{myBackingBean.createListener} someway. I'm using this method (along with some overloads) to obtain a MethodExpression: protected MethodExpression getMethodExpression(String beanName, String methodName, Class<?> expectedReturnType, Class<?>[] expectedParamTypes) { ExpressionFactory expressionFactory; MethodExpression method; ELContext elContext; String el; el = String.format("#{%s['%s']}", beanName, methodName); expressionFactory = getApplication().getExpressionFactory(); elContext = getFacesContext().getELContext(); method = expressionFactory.createMethodExpression(elContext, el, expectedReturnType, expectedParamTypes); return method; } and the click event handler should look like: public void saveSubaccountListener(ActionEvent event) { MethodExpression method; ... method = getMethodExpression( "backingBean", "createSubaccountListener", SubuserBean.class); if (method != null) method.invoke( getFacesContext().getELContext(), new Object[] { _editedSubuser }); } That works fine as long as I provide an existing bean name (myBackingBean), but if I use backingBean the invoke() doesn't work due to the following error: javax.el.PropertyNotFoundException: Target Unreachable, identifier 'backingBean' resolved to null Is there a way I can retrieve from the facelet backing bean the value of a parameter that has been passed to the facelet? In my case, the value of backingBean, which should be myBackingBean? I've searched for and tried different solutions, but with no luck yet.

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• How To Deal With Exceptions In Large Code Bases

  - by peter

  Hi All, I have a large C# code base. It seems quite buggy at times, and I was wondering if there is a quick way to improve finding and diagnosing issues that are occuring on client PCs. The most pressing issue is that exceptions occur in the software, are caught, and even reported through to me. The problem is that by the time they are caught the original cause of the exception is lost. I.e. If an exception was caught in a specific method, but that method calls 20 other methods, and those methods each call 20 other methods. You get the picture, a null reference exception is impossible to figure out, especially if it occured on a client machine. I have currently found some places where I think errors are more likely to occur and wrapped these directly in their own try catch blocks. Is that the only solution? I could be here a long time. I don't care that the exception will bring down the current process (it is just a thread anyway - not the main application), but I care that the exceptions come back and don't help with troubleshooting. Any ideas? I am well aware that I am probably asking a question which sounds silly, and may not have a straightforward answer. All the same some discussion would be good.

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• PHP sessions dying in a few seconds

  - by beauchette

  I have a problem with my server : my sessions are dying on their own after a few seconds. here are two page examples : page1.php : <? session_start(); $_SESSION['x'] = 'moo'; ?> page2.php : <? session_start(); echo $_SESSION['x']; ?> php's settings are debian's untouched : no auto start, 1440 seconds maxlifetime, etc so, if I visit page1.php et then page2.php I'm supposed to see 'moo' for 24 minutes, in my case, you have 'moo' for about 5 seconds. Then I observed that the actual session file, was 44 bytes long, and then 0 a few seconds later, without any other intervention than a few 'ls' to observe the phenomenon, I really have no clue as to what happens and any help would be appreciated. EDIT: after some fiddling (mainly not doing much besides restarting my server 3 or 4 times) I was able to have my quick example working. and then I noticed that sessions in my session.save_path directory are all 44 bytes except for some that are 0 bytes, so it's like it's working but not always. which is even more frustrating.

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• DB Design to store custom fields for a table

  - by Fazal

  Hi All, this question came up based on the responses I got for the question http://stackoverflow.com/questions/2785033/getting-wierd-issue-with-to-number-function-in-oracle As everyone suggested that storing Numeric values in VARCHAR2 columns is not a good practice (which I totally agree with), I am wondering about a basic Design choice our team has made and whether there are better way to design. Problem Statement : We Have many tables where we want to give certain number of custom fields. The number of required custom fields is known, but what kind of attribute is mapped to the column is available to the user E.g. I am putting down a hypothetical scenario below Say you have a laptop which stores 50 attribute values for every laptop record. Each laptop attributes are created by the some admin who creates the laptop. A user created a laptop product lets say lap1 with attributes String, String, numeric, numeric, String Second user created laptop lap2 with attributes String,numeric,String,String,numeric Currently there data in our design gets persisted as following Laptop Table Id Name field1 field2 field3 field4 field5 1 lap1 lappy lappy 12 13 lappy 2 lap2 lappy2 13 lappy2 lapp2 12 This example kind of simulates our requirement and our design Now here if somebody is lookinup records for lap2 table doing a comparison on field2, We need to apply TO_NUMBER. select * from laptop where name='lap2' and TO_NUMBER(field2) < 15 TO_NUMBER fails in some cases when query plan decides to first apply to_number instead of the other filter. QUESTION Is this a valid design? What are the other alternative ways to solve this problem One of our team mates suggested creating tables on the fly for such cases. Is that a good idea How do popular ORM tools give custom fields or flex fields handling? I hope I was able to make sense in the question. Sorry for such a long text.. This causes us to use TO_NUMBER when queryio

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• Tips for Using Multiple Development Systems

  - by Tim Lytle

  When I travel, I don't pack up the desktop I use in the office and take it with me. Maybe I should, but I don't. However, since I'm a contract programmer I like to be able to work wherever I am: I'm mostly thinking of web development here. Version Control goes a long way in keeping sane and working on multiple projects on multiple systems (two or three computers); however, there are the issues of: IDE settings - different display sizes mean the IDE settings can't be completely synced, if at all. Database - if the database is 'external' (even if it's running on the same system, it's not in version control), how do you maintain the needed syncs of structure. Development Stack - Some projects need non-standard extensions, libraries, etc installed. Just an overview of some of the hassle involved with developing on multiple systems. I'll probably end up asking some specific questions, but I thought a CW style tips might reveal some things I would even think to ask about. Update: I guess this would also address tips to make upgrading/replacing your development system easier (something I've just done). So, one tip per answer please, so the 'top' tips are easy to find. How do you make it easier to develop on multiple systems, or to transfer work after upgrading/replaceing a development system?

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• Issue with creating index organized table

  - by mtim

  I'm having a weird problem with index organized table. I'm running Oracle 11g standard. i have a table src_table SQL> desc src_table; Name Null? Type --------------- -------- ---------------------------- ID NOT NULL NUMBER(16) HASH NOT NULL NUMBER(3) ........ SQL> select count(*) from src_table; COUNT(*) ---------- 21108244 now let's create another table and copy 2 columns from src_table set timing on SQL> create table dest_table(id number(16), hash number(20), type number(1)); Table created. Elapsed: 00:00:00.01 SQL> insert /*+ APPEND */ into dest_table (id,hash,type) select id, hash, 1 from src_table; 21108244 rows created. Elapsed: 00:00:15.25 SQL> ALTER TABLE dest_table ADD ( CONSTRAINT dest_table_pk PRIMARY KEY (HASH, id, TYPE)); Table altered. Elapsed: 00:01:17.35 It took Oracle < 2 min. now same exercise but with IOT table SQL> CREATE TABLE dest_table_iot ( id NUMBER(16) NOT NULL, hash NUMBER(20) NOT NULL, type NUMBER(1) NOT NULL, CONSTRAINT dest_table_iot_PK PRIMARY KEY (HASH, id, TYPE) ) ORGANIZATION INDEX; Table created. Elapsed: 00:00:00.03 SQL> INSERT /*+ APPEND */ INTO dest_table_iot (HASH,id,TYPE) SELECT HASH, id, 1 FROM src_table; "insert" into IOT takes 18 hours !!! I have tried it on 2 different instances of Oracle running on win and linux and got same results. What is going on here ? Why is it taking so long ?

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• Why am I getting this error when overriding an inherited method?

  - by Sergio Tapia

  Here's my parent class: public abstract class BaseFile { public string Name { get; set; } public string FileType { get; set; } public long Size { get; set; } public DateTime CreationDate { get; set; } public DateTime ModificationDate { get; set; } public abstract void GetFileInformation(); public abstract void GetThumbnail(); } And here's the class that's inheriting it: public class Picture:BaseFile { public override void GetFileInformation(string filePath) { FileInfo fileInformation = new FileInfo(filePath); if (fileInformation.Exists) { Name = fileInformation.Name; FileType = fileInformation.Extension; Size = fileInformation.Length; CreationDate = fileInformation.CreationTime; ModificationDate = fileInformation.LastWriteTime; } } public override void GetThumbnail() { } } I thought when a method was overridden, I could do what I wanted with it. Any help please? :)

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• Multi-module Maven build

  - by Don

  Hi, My project has a fairly deep graph of Maven modules. The root POM has the following plugin configured <plugins> <plugin> <groupId>org.jvnet</groupId> <artifactId>animal-sniffer</artifactId> <version>1.2</version> <configuration> <signature> <groupId>org.jvnet.animal-sniffer</groupId> <artifactId>java1.4</artifactId> <version>1.0</version> </signature> </configuration> </plugin> </plugins> If I invoke this target from the command line in the root directory via: mvn animal-sniffer:check Then it works fine as long as the current module extends (either directly or indirectly) from the root POM. However there are many children (or grandchildren) of the root module, which do not inherit from that module's POM. In this case, the goal fails because it cannot find the necessary configuration [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] One or more required plugin parameters are invalid/missing for 'animal-sniffer:check' [0] Inside the definition for plugin 'animal-sniffer' specify the following: <configuration> ... <signature>VALUE</signature> </configuration>. When configuring this plugin in the root module, is there any way to exclude a list of sub-modules either by name, or by packaging type? Thanks, Donal

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• IE7 Problem with sIFR when <br> is inside an H3

  - by David Fox

  I have a problem I just discovered when viewing certain pages in IE7. If I have a very long header that wraps to a second line, or worse, if I put a BR in the middle, that throws off the spacing. One page to look at: broken example1 You'll notice that the margin at the top of the page gets offset as the headings are rendered, throwing everything off. I'm using code like this: <h3 style="margin:0"><a href="../books/msc1.html">Middle School Confidential™<br> Book 1: Be Confident in Who You Are</a></h3> but repeated many times to exaggerate the problem. I tried another test where I removed the BR and let the lines wrap naturally. This is an improvement in terms of the spacing, but it doesn't fix the problem. (Same URL but make it m1.html) In the third example, each heading takes up only one line (m2.html) One option would be to just split up the heading onto two lines, each with its on H tags. But since these are links, then it will appear that the first line might go to one place, and the second to another, since they wouldn't change color simultaneously as you roll over them. So, any solutions to this? I believe I have the current version of sIFR 3. I don't want to upgrade to IE8 until I know this is resolved. Thanks!

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• How to systematically generate images from data?

  - by adamvickers

  I work for a performing arts nonprofit. We have seating charts for each of the theaters we work with; each seating chart shows the number of sections, the shape of each section, and the number of rows in each section. We'd like to create dynamic seating charts based on this info. We'd like them to look/feel kinda like this: http://www.fansnap.com/tickets/177754-on. But the tricky part is we'd like to be able to store all the info about each theater (the section names, shape/size of each section, and number of rows in each section) as data and then build a system that reads this data and uses it to create a dynamic map. I'm a life-long web developer, but I don't have have any experience with a difficult graphics problem like this. I realize it's a complex problem and I don't expect anyone to give me a complete answer here, but I would love direction on where I should be looking for more info. Is what I'm describing possible? Does this sort of technique have a name? Where can I learn more about how to accomplish this? What software should I use? Any info would be helpful.

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