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  • Optimise & improve performance of this MYSQL query

    - by David
    SELECT u.id, u.honour, COUNT(*) + 1 AS rank FROM user_info u INNER JOIN user_info u2 ON u.honour < u2.honour WHERE u.id = '$id' AND u2.status = 'Alive' AND u2.rank != '14' This query is currently utterly raping my server. It works out based on your honour what rank you are within the 'user_info' table which stores it out of all our users. Screenshot for explain. http://cl.ly/370z0v2Y3v2X1t1r1k2A SELECT u.id, u.honour, COUNT(*)+1 as rank FROM user_info u USE INDEX (prestigeOptimiser) INNER JOIN user_info u2 ON u.honour < u2.honour WHERE u.id='3' AND u2.status='Alive' AND u2.rank!='14'

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  • Getting the most frequent items without counting every item

    - by DeadMonkeyWalkin
    Hi. I was wondering if there was an algorithm for counting "most frequent items" without having to keep a count of each item? For example, let's say I was a search engine and wanted to keep track of the 10 most popular searches. What I don't want to do is keep a counter of every query since there could be too many queries for me to count (and most them will be singletons). Is there a simple algorithm for this? Maybe something that is probabilistic? Thanks!

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  • silverlight and windows workflow foundation

    - by wissem
    private void btnUpdate_Click(object sender, RoutedEventArgs e) { xxxxxxx.Workflow1_WebServiceSoapClient zer = new xxxxx.Workflow1_WebServiceSoapClient(); zer.demanderSubmitReportCompleted += new EventHandler<xxxxxxxxxxxxxxx.demanderSubmitReportCompletedEventArgs>(service2); zer.demanderSubmitReportAsync("zzz", 20000); } public void service2(object sender, xxxxx.demanderSubmitReportCompletedEventArgs e) { string a = e.Result; } I'm trying to call a windows workflow foundation published as a web service from a Silverlight project. When I call it from a console application it works fine because I can add a web reference then I just make an instance of that webservice then I invoke the method I want. The problem is in the silverlight project cause i can just add a service reference so I find myself working with soap stuff that doesn't work at all, and here is the code error: here is the code:i change it a litle bit in english Error in exécution Microsoft JScript: Unhandled Error in Silverlight Application exception happened in the operation, résult not valide. Consult InnerException for more information. in System.ComponentModel.AsyncCompletedEventArgs.RaiseExceptionIfNecessary() in AEDSilverlightIntegrated.ServiceReference2.demanderSubmitReportCompletedEventArgs.get_Result() in AEDSilverlightIntegrated.SilverEntryAedHeaderNew.mmm_demanderSubmitReportCompleted(Object sender, demanderSubmitReportCompletedEventArgs e) in AEDSilverlightIntegrated.ServiceReference2.Workflow1_WebServiceSoapClient.OndemanderSubmitReportCompleted(Object state)

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  • I am having trouble with a perl Script

    - by Jonathan Mori
    I have web log files and I was having a lot of trouble, being new with perl. I just need a script to find a count of each of the images that were found. I was able to list them but I'm unsure of how to just get a count, say something like "There were x jpgs and x gifs viewed". The web logs look like this. 24.131.83.162 - - [28/Jan/2007:00:00:00 -0500] "GET /~taler/images/index_09.jpg HTTP/1.1" 200 1563 207.46.98.53 - - [28/Jan/2007:00:00:04 -0500] "GET /%7Edist/programs/PhD/PhDGuide/guideA.htm HTTP/1.0" 200 19090 74.6.74.184 - - [28/Jan/2007:00:00:12 -0500] "GET /%7Embsclass/hall_of_fame/myicon.ico HTTP/1.0" 200 760 58.68.24.3 - - [28/Jan/2007:00:00:16 -0500] "GET /~dtipper/tipper.html HTTP/1.1" 200 5896 58.68.24.3 - - [28/Jan/2007:00:00:16 -0500] "GET /~dtipper/gifs/head.jpg HTTP/1.1" 200 18318

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  • A Simple C# DLL - how do I call it from Excel, Access, VBA, VB6 ?

    - by divinci
    Hi all, I have a simple class library written in c#. using System; namespace TestDll { public class Test { public string HelloWorld { get { return "Hello World"; } } } } My question is how can I call this HelloWorld function from Microsoft Office Visual Basic (which I think is VB6)? My first step was to add the DLL as a reference - but on browsing and selecting the compiled DLL the message "Can't add a reference to the specified file." was thrown. Can anyone point me in the right direction as to why/how to get this working? Thanks in advance SO!

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  • Technical non-terminating condition in a loop

    - by Snarfblam
    Most of us know that a loop should not have a non-terminating condition. For example, this C# loop has a non-terminating condition: any even value of i. This is an obvious logic error. void CountByTwosStartingAt(byte i) { // If i is even, it never exceeds 254 for(; i < 255; i += 2) { Console.WriteLine(i); } } Sometimes there are edge cases that are extremely unlikeley, but technically constitute non-exiting conditions (stack overflows and out-of-memory errors aside). Suppose you have a function that counts the number of sequential zeros in a stream: int CountZeros(Stream s) { int total = 0; while(s.ReadByte() == 0) total++; return total; } Now, suppose you feed it this thing: class InfiniteEmptyStream:Stream { // ... Other members ... public override int Read(byte[] buffer, int offset, int count) { Array.Clear(buffer, offset, count); // Output zeros return count; // Never returns -1 (end of stream) } } Or more realistically, maybe a stream that returns data from external hardware, which in certain cases might return lots of zeros (such as a game controller sitting on your desk). Either way we have an infinite loop. This particular non-terminating condition stands out, but sometimes they don't. A completely real-world example as in an app I'm writing. An endless stream of zeros will be deserialized into infinite "empty" objects (until the collection class or GC throws an exception because I've exceeded two billion items). But this would be a completely unexpected circumstance (considering my data source). How important is it to have absolutely no non-terminating conditions? How much does this affect "robustness?" Does it matter if they are only "theoretically" non-terminating (is it okay if an exception represents an implicit terminating condition)? Does it matter whether the app is commercial? If it is publicly distributed? Does it matter if the problematic code is in no way accessible through a public interface/API? Edit: One of the primary concerns I have is unforseen logic errors that can create the non-terminating condition. If, as a rule, you ensure there are no non-terminating conditions, you can identify or handle these logic errors more gracefully, but is it worth it? And when? This is a concern orthogonal to trust.

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  • Repeat Customers Each Year (Retention)

    - by spazzie
    I've been working on this and I don't think I'm doing it right. |D Our database doesn't keep track of how many customers we retain so we looked for an alternate method. It's outlined in this article. It suggests you have this table to fill in: Year Number of Customers Number of customers Retained in 2009 Percent (%) Retained in 2009 Number of customers Retained in 2010 Percent (%) Retained in 2010 .... 2008 2009 2010 2011 2012 Total The table would go out to 2012 in the headers. I'm just saving space. It tells you to find the total number of customers you had in your starting year. To do this, I used this query since our starting year is 2008: select YEAR(OrderDate) as 'Year', COUNT(distinct(billemail)) as Customers from dbo.tblOrder where OrderDate >= '2008-01-01' and OrderDate <= '2008-12-31' group by YEAR(OrderDate) At the moment we just differentiate our customers by email address. Then you have to search for the same names of customers who purchased again in later years (ours are 2009, 10, 11, and 12). I came up with this. It should find people who purchased in both 2008 and 2009. SELECT YEAR(OrderDate) as 'Year',COUNT(distinct(billemail)) as Customers FROM dbo.tblOrder o with (nolock) WHERE o.BillEmail IN (SELECT DISTINCT o1.BillEmail FROM dbo.tblOrder o1 with (nolock) WHERE o1.OrderDate BETWEEN '2008-1-1' AND '2009-1-1') AND o.BillEmail IN (SELECT DISTINCT o2.BillEmail FROM dbo.tblOrder o2 with (nolock) WHERE o2.OrderDate BETWEEN '2009-1-1' AND '2010-1-1') --AND o.OrderDate BETWEEN '2008-1-1' AND '2013-1-1' AND o.BillEmail NOT LIKE '%@halloweencostumes.com' AND o.BillEmail NOT LIKE '' GROUP BY YEAR(OrderDate) So I'm just finding the customers who purchased in both those years. And then I'm doing an independent query to find those who purchased in 2008 and 2010, then 08 and 11, and then 08 and 12. This one finds 2008 and 2010 purchasers: SELECT YEAR(OrderDate) as 'Year',COUNT(distinct(billemail)) as Customers FROM dbo.tblOrder o with (nolock) WHERE o.BillEmail IN (SELECT DISTINCT o1.BillEmail FROM dbo.tblOrder o1 with (nolock) WHERE o1.OrderDate BETWEEN '2008-1-1' AND '2009-1-1') AND o.BillEmail IN (SELECT DISTINCT o2.BillEmail FROM dbo.tblOrder o2 with (nolock) WHERE o2.OrderDate BETWEEN '2010-1-1' AND '2011-1-1') --AND o.OrderDate BETWEEN '2008-1-1' AND '2013-1-1' AND o.BillEmail NOT LIKE '%@halloweencostumes.com' AND o.BillEmail NOT LIKE '' GROUP BY YEAR(OrderDate) So you see I have a different query for each year comparison. They're all unrelated. So in the end I'm just finding people who bought in 2008 and 2009, and then a potentially different group that bought in 2008 and 2010, and so on. For this to be accurate, do I have to use the same grouping of 2008 buyers each time? So they bought in 2009 and 2010 and 2011, and 2012? This is where I'm worried and not sure how to proceed or even find such data. Any advice would be appreciated! Thanks!

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  • Track Pedestrians

    - by 2vision2
    I am using OpenCV sample code “peopledetect.cpp” to detect and track pedestrians. The code uses HoG for feature extraction and SVM for classification. Please find the reference paper used here. The camera is mounted on the wall at a height of 10 feet and 45 degree down. There is no restriction on the pedestrian movement within the frame. I want to track the detected pedestrians’ movement within the frame. The issue I am facing is pedestrians are detected only in the middle region of the frame as most of the features are not visible as soon as the pedestrian enters the frame region. I want to track each person’s movement in the entire frame region. How to do it? Is tracking required? Can anyone give any reference to blogs/codes?

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  • Returning a recordcount from a subquery in a result set.

    - by KeRiCr
    I am attempting to return a rowcount from a subquery as part of a result set. Here is a sample that I've tried that didn't work: SELECT recordID , GroupIdentifier , count() AS total , (SELECT COUNT() FROM table WHERE intActingAsBoolean = 1) AS Approved FROM table WHERE date_format(Datevalue, '%Y%m%d') BETWEEN 'startDate' AND 'endDate' GROUP BY groupIdentifier What I'm attempting to return for 'Approved' is the number of records for the grouped value where intActingAsBoolean = 1. I have also tried modifying the where clause by giving the main query a table alias and applying an AND clause to match the groupidentifier in the subquery to the main query. None of these are returning the correct results. The query as written returns all records in the table where intActingAsBoolean = 1. This query is being run against a MySQL database.

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  • Insert problem using ADO with classic ASP

    - by Kemal Akcali
    ' Setting variables Dim con, sql_insert, data_source data_source = "project_db" sql_insert = "insert into cart ( UserID,Count,ProductName,ProductDescription,ProductPrice) values ('"&user_id&"','"&count&"','"&product_name&"','"&product_description&"','"&product_price&"')" ' Creating the Connection Object and opening the database Set con = Server.CreateObject("ADODB.Connection") con.Open data_source ' Executing the sql insertion code con.Execute sql_insert ' Done. Now Close the connection con.Close Set con = Nothing AS you can see , it is a simple code . and it worked in my local host for 5 or 6 times. but now it didn't work. What's the problem ? I think , it's about my database or memory. i setup 2 different iis in 2 different computer and they behave same... please help.. Thanks

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  • Time diff calculations where date and time are in seperate columns

    - by pedalpete
    I've got a query where I'm trying to get the hours in duration (eg 6.5 hours) between two different times. In my database, time and date are held in different fields so I can efficiently query on just a startDate, or endDate as I never query specifically on time. My query looks like this SELECT COUNT(*), IFNULL(SUM(TIMEDIFF(endTime,startTime)),0) FROM events WHERE user=18 Sometimes an event will go overnight, so the difference between times needs to take into account the differences between the dates as well. I've been trying SELECT COUNT(*), IFNULL(SUM(TIMEDIFF(CONCAT(endDate,' ',endTime),CONCAT(startDate,' ',startTime))),0) FROM events WHERE user=18 Unfortunately I only get errors when I do this, and I can't seem to combine the two fields into a single timestamp.

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  • Global NSMutableArray doesn't seem to be holding values

    - by diatrevolo
    I have a Cocos2D iPhone application that requires a set of CGRects overlaid on an image to detect touches within them. "Data" below is a class that holds values parsed from an XML file. "delegateEntries" is a NSMutableArray that contains several "data" objects, pulled from another NSMutableArray called "entries" that lives in the application delegate. For some strange reason, I can get at these values without problems in the init function, but further down the class in question, I try to get at these values, and the application crashes without an error message (as an example, I put in the "ccTouchBegan" method which accessess this data through the "populateFieldsForTouchedItem" method. Can anyone see why these values would not be accessible from other methods? No objects get released until dealloc. Thanks in advance! @synthesize clicked, delegate, data, image, blurImage, normalImage, arrayOfRects, delegateEntries; - (id)initWithTexture:(CCTexture2D *)aTexture { if( (self=[super initWithTexture:aTexture] )) { arrayOfRects = [[NSMutableArray alloc] init]; delegateEntries = [[NSMutableArray alloc] init]; delegate = (InteractivePIAppDelegate *)[[UIApplication sharedApplication] delegate]; delegateEntries = [delegate entries]; data = [delegateEntries objectAtIndex:0]; NSLog(@"Assigning %@", [[delegateEntries objectAtIndex:0] backgroundImage]); NSLog(@"%@ is the string", [[data sections] objectAtIndex:0]); //CGRect rect; NSLog(@"Count of array is %i", [delegateEntries count]); //collect as many items as there are XML entries for(int i=0; i<[delegateEntries count]; i++) { if([[delegateEntries objectAtIndex:i] xPos]) { NSLog(@"Found %i items", i+1); [arrayOfRects addObject:[NSValue valueWithCGRect:CGRectMake([[[delegateEntries objectAtIndex:i] xPos] floatValue], [[[delegateEntries objectAtIndex:i] yPos] floatValue], [[[delegateEntries objectAtIndex:i] xBounds] floatValue], [[[delegateEntries objectAtIndex:i] yBounds] floatValue])]]; } else { NSLog(@"Nothing"); } } //remove the following once the NSMutableArray from above works (legacy) blurImage = [[NSString alloc] initWithString:[data backgroundBlur]]; NSLog(@"5"); normalImage = [[NSString alloc] initWithString:[data backgroundImage]]; clicked = NO; } return self; } And then: - (void)populateFieldsForTouchedItem:(TouchedRect)touchInfo { Data *touchDatum = [[Data alloc] init]; touchDatum = [[self delegateEntries] objectAtIndex:touchInfo.recordNumber]; NSLog(@"Assigning %@", [[[self delegateEntries] objectAtIndex:touchInfo.recordNumber] backgroundImage]); rect = [[arrayOfRects objectAtIndex:touchInfo.recordNumber] CGRectValue]; image = [[NSString alloc] initWithString:[[touchDatum sections] objectAtIndex:0]]; [touchDatum release]; } - (BOOL)ccTouchBegan:(UITouch *)touch withEvent:(UIEvent *)event { TouchedRect touchInfo = [self containsTouchLocation:touch]; NSLog(@"Information pertains to %i", touchInfo.recordNumber); if ( !touchInfo.touched && !clicked ) { //needed since the touch location changes when zoomed NSLog(@"NOPE"); return NO; } [self populateFieldsForTouchedItem:touchInfo]; NSLog(@"YEP"); return YES; }

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  • php functions within functions.

    - by Adamski
    Hi all, ihave created a simple project to help me get to grips with php and mysql, but have run into a minor issue, i have a working solution but would like to understand why i cannot run this code successfully this way, ill explain: i have a function, function fetch_all_movies(){ global $connection; $query = 'select distinct * FROM `'.TABLE_MOVIE.'` ORDER BY movieName ASC'; $stmt = mysqli_prepare($connection,$query); mysqli_execute($stmt); mysqli_stmt_bind_result($stmt,$id,$name,$genre,$date,$year); while(mysqli_stmt_fetch($stmt)){ $editUrl = "index.php?a=editMovie&movieId=".$id.""; $delUrl = "index.php?a=delMovie&movieId=".$id.""; echo "<tr><td>".$id."</td><td>".$name."</td><td>".$date."</td><td>".get_actors($id)."</td><td><a href=\"".$editUrl."\">Edit</a> | <a href=\"".$delUrl."\">Delete</a></td></tr>"; } } this fetches all the movies in my db, then i wish to get the count of actors for each film, so i pass in the get_actors($id) function which gets the movie id and then gives me the count of how many actors are realted to a film. here is the function for that: function get_actors($movieId){ global $connection; $query = 'SELECT DISTINCT COUNT(*) FROM `'.TABLE_ACTORS.'` WHERE movieId = "'.$movieId.'"'; $result = mysqli_query($connection,$query); $row = mysqli_fetch_array($result); return $row[0]; } the functions both work perfect when called separately, i just would like to understand when i pass the function inside a function i get this warning: Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in /Applications/MAMP/htdocs/movie_db/includes/functions.inc.php on line 287 could anyone help me understand why? many thanks.

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  • Enumerable.Range in and Expression and Entity Framework

    - by eka808
    I'm currently developping an expression method (used in linq to entity queries) who has to give me a daycount for a given period (start date and end date) decrementing this daycount if specials days are in the period. My idea was the following : Generate an enumerable with all the dates (and with Enumerable.Range) Make a .Where on this enumerable to remove the specials dates Like a MyEnumerable.Where(a = a != "20120101") After that, return a MyEnumerable.Count() I come with this code : return (p) => Enumerable .Range(1, 4) .Where(a => a != 20120101) .AsQueryable() .Count() I tried to cast as a list, as a queryable, both (like the example) and no way ! it doesn't work ! I always get this error : LINQ to Entities does not recognize the method 'System.Collections.Generic.IEnumerable`1[System.Int32] Range(Int32, Int32)' method, and this method cannot be translated into a store expression. Have you got an idea about that ? Using an enumerable is of course not mandatory, any working solutions is good ^^ Thank's by advance !

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  • What happens to an instance of ServerSocket blocked inside accept(), when I drop all references to i

    - by Hanno Fietz
    In a multithreaded Java application, I just tracked down a strange-looking bug, realizing that what seemed to be happening was this: one of my objects was storing a reference to an instance of ServerSocket on startup, one thread would, in its main loop in run(), call accept() on the socket while the socket was still waiting for a connection, another thread would try to restart the component under some conditions, the restart process missed the cleanup sequence before it reached the initialization sequence as a result, the reference to the socket was overwritten with a new instance, which then wasn't able to bind() anymore the socket which was blocking inside the accept() wasn't accessible anymore, leaving a complete shutdown and restart of the application as the only way to get rid of it. Which leaves me wondering: with no references left to the ServerSocket instance, what would free the socket for a new connection? At what point would the ServerSocket become garbage collected? In general, what are good practices I can follow to avoid this type of bug?

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  • group by with 3 diffrent

    - by NN
    I have 2 table and I wanna a query with 3 column result in on of them 2 column with view count and title name and in the other 1 column with type_ and i wanna to grouping type_ with max(view count) and show the them title but i didn't have any idea about grouping expression. i think we can solve in by using sub query but i don't know which column use in group by. 2 table join with this expression class pk=resource key i exam this query: SELECT t.title,j.type_ FROM tags asset t,journal article j where type_ in (select type_ from journal article,tags asset where class pk=resource key group by type_) but the answer was wrong

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  • JarOutputStream put parent folder before my-wanted folder

    - by adhitya kristanto
    I tried to make jar with code from How to use JarOutputStream to create a JAR file? but that code always makes new parent folder of my input file/folder before it's inserted into .jar Folder's Path that I want to be added into jar: C:/Trial/MyFolder Folder that I want in MyJar.jar: MyFolder But Folder that was inserted in MyJar.jar: Trial Has it to be done that way? Thanks. here is the code: import EditorXML.GlobalStatus.GlobalStatus; import java.io.BufferedInputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.util.jar.JarEntry; import java.util.jar.JarOutputStream; /** * * @author Photosphere */ public class JarCreatingProgram { public JarCreatingProgram() { } public void proceedNow() throws IOException{ File ed = new File("C:/Trial/EditingDini"); File meta = new File("C:/Trial/META-INF"); File net = new File("C:/Trial/net"); File org = new File("C:/Trial/org"); JarOutputStream target = new JarOutputStream(new FileOutputStream("D:/EditingDiniApp.jar")); add(ed, target); add(meta, target); add(net, target); add(org, target); target.close(); } private static void add(File source, JarOutputStream target) throws IOException { BufferedInputStream in = null; try{ if (source.isDirectory()) { String name = source.getPath().replace("\\", "/"); if (!name.isEmpty()) { if (!name.endsWith("/")) name += "/"; JarEntry entry = new JarEntry(name); entry.setTime(source.lastModified()); target.putNextEntry(entry); System.out.println("ENTRY DALAM IF: "+entry.toString()); target.closeEntry(); } for (File nestedFile: source.listFiles()) add(nestedFile, target); return; } JarEntry entry = new JarEntry(source.getPath().replace("\\", "/")); entry.setTime(source.lastModified()); target.putNextEntry(entry); in = new BufferedInputStream(new FileInputStream(source)); System.out.println("ENTRY: "+entry.toString()); byte[] buffer = new byte[1024]; while (true) { int count = in.read(buffer); if (count == -1) break; target.write(buffer, 0, count); } target.closeEntry(); } finally{ if (in != null) in.close(); } } }

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  • oracle update procedure problem

    - by murali
    hi, i want to update the following procedure in the oracle table..but it is throwing error CREATE OR REPLACE PROCEDURE update_keywords (aKEYWORD IN VARCHAR2, aCOUNT IN NUMBER) AS BEGIN update searchable_keywords set KEYWORD =:new.aKEYWORD or COUNT =:new.aCOUNT where KEUWORD_ID = : old.KEYWORD_ID; END; this is my procedure, i want to update the keyword & count in the searchable_keywords table with keyword_id(primary key) but it is throwing error as follows... LINE/COL ERROR 3/4 PL/SQL: SQL Statement ignored 4/17 PLS-00049: bad bind variable 'NEW.AKEYWORD' 4/31 PL/SQL: ORA-00933: SQL command not properly ended 4/41 PLS-00049: bad bind variable 'NEW.ACOUNT' can you pls help me slove this problem..thanks

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  • Use multiple inheritance to discriminate useage roles?

    - by Arne
    Hi fellows, it's my flight simulation application again. I am leaving the mere prototyping phase now and start fleshing out the software design now. At least I try.. Each of the aircraft in the simulation have got a flight plan associated to them, the exact nature of which is of no interest for this question. Sufficient to say that the operator way edit the flight plan while the simulation is running. The aircraft model most of the time only needs to read-acess the flight plan object which at first thought calls for simply passing a const reference. But ocassionally the aircraft will need to call AdvanceActiveWayPoint() to indicate a way point has been reached. This will affect the Iterator returned by function ActiveWayPoint(). This implies that the aircraft model indeed needs a non-const reference which in turn would also expose functions like AppendWayPoint() to the aircraft model. I would like to avoid this because I would like to enforce the useage rule described above at compile time. Note that class WayPointIter is equivalent to a STL const iterator, that is the way point can not be mutated by the iterator. class FlightPlan { public: void AppendWayPoint(const WayPointIter& at, WayPoint new_wp); void ReplaceWayPoint(const WayPointIter& ar, WayPoint new_wp); void RemoveWayPoint(WayPointIter at); (...) WayPointIter First() const; WayPointIter Last() const; WayPointIter Active() const; void AdvanceActiveWayPoint() const; (...) }; My idea to overcome the issue is this: define an abstract interface class for each usage role and inherit FlightPlan from both. Each user then only gets passed a reference of the appropriate useage role. class IFlightPlanActiveWayPoint { public: WayPointIter Active() const =0; void AdvanceActiveWayPoint() const =0; }; class IFlightPlanEditable { public: void AppendWayPoint(const WayPointIter& at, WayPoint new_wp); void ReplaceWayPoint(const WayPointIter& ar, WayPoint new_wp); void RemoveWayPoint(WayPointIter at); (...) }; Thus the declaration of FlightPlan would only need to be changed to: class FlightPlan : public IFlightPlanActiveWayPoint, IFlightPlanEditable { (...) }; What do you think? Are there any cavecats I might be missing? Is this design clear or should I come up with somethink different for the sake of clarity? Alternatively I could also define a special ActiveWayPoint class which would contain the function AdvanceActiveWayPoint() but feel that this might be unnecessary. Thanks in advance!

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  • String Storage and Retrieval in Android

    - by dweebsonduty
    I have a program that has items with 3 attributes. Name(String) : Count(String) : Amount(String) Currently I am writing the database when someone is trying to access a section then reading from the database. The writing is taking too long. So my question is how can I perhaps create a nested array where I can say if name = carrot then print carrot['count'] and carrot['amount']. I am very new to Java so some sample code would be great. Or any other suggestions that you may have as far as tackling this issue.

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  • Perfect Forwarding to async lambda

    - by Alexander Kondratskiy
    I have a function template, where I want to do perfect forwarding into a lambda that I run on another thread. Here is a minimal test case which you can directly compile: #include <thread> #include <future> #include <utility> #include <iostream> #include <vector> /** * Function template that does perfect forwarding to a lambda inside an * async call (or at least tries to). I want both instantiations of the * function to work (one for lvalue references T&, and rvalue reference T&&). * However, I cannot get the code to compile when calling it with an lvalue. * See main() below. */ template <typename T> std::string accessValueAsync(T&& obj) { std::future<std::string> fut = std::async(std::launch::async, [](T&& vec) mutable { return vec[0]; }, std::forward<T>(obj)); return fut.get(); } int main(int argc, char const *argv[]) { std::vector<std::string> lvalue{"Testing"}; // calling with what I assume is an lvalue reference does NOT compile std::cout << accessValueAsync(lvalue) << std::endl; // calling with rvalue reference compiles std::cout << accessValueAsync(std::move(lvalue)) << std::endl; // I want both to compile. return 0; } For the non-compiling case, here is the last line of the error message which is intelligible: main.cpp|13 col 29| note: no known conversion for argument 1 from ‘std::vector<std::basic_string<char> >’ to ‘std::vector<std::basic_string<char> >&’ I have a feeling it may have something to do with how T&& is deduced, but I can't pinpoint the exact point of failure and fix it. Any suggestions? Thank you! EDIT: I am using gcc 4.7.0 just in case this could be a compiler issue (probably not)

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  • Is It Safe to Cast Away volatile?

    - by Yan Cheng CHEOK
    Most of the time, I am doing this way. class a { public: ~ a() { i = 100; // OK delete (int *)j; // Compiler happy. But, is it safe? // Error : delete j; } private: volatile int i; volatile int *j; }; int main() { a aa; } However, I saw an article here: https://www.securecoding.cert.org/confluence/display/seccode/EXP32-C.+Do+not+access+a+volatile+object+through+a+non-volatile+reference Casting away volatile allows access to an object through a non-volatile reference. This can result in undefined and perhaps unintended program behavior. So, what will be the workaround for my above code example?

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  • Are ASP.NET readymade controls really production worthy ?

    - by Anil Namde
    I have come across the ASP.NET ready made controls like grid, repeater... etc. For example while dealing with GRID i remember following facts, ASP.NET V1.1 has DataGrid with "virtual row count" which is heavily used for custom paging which is need of big sites to perform well. ASP.NET V2.0 added the GridView with all sort of cool features but also split the DataSource parts as different component. Also "virtual row count" is not supported and for pagination to be done DataSource control is need to be used. After all these thing i thought that ASP.NET control are not made to be used as is for the development. Please let me know whether i am right or wrong? Also if you think i am wrong PLEASE provide inputs/links which can help me come out of this thinking of mine.

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  • inheriting scope from a has_many relationship

    - by hb922
    I am using ruby on rails 3.1 and have 2 models, an event and a group. Each event has_many groups, but has to have at least one "master" group, where the column :is_master = true Class Group < ActiveRecord::Base has_many :users belongs_to :event scope :master, where (:is_master => true) end Class Event< ActiveRecord::Base has_many :groups def master_group groups.master end end I want to be able to default all properties of the master group to the event, so for example, event.users.count should be the same as event.master_group.users.count. Is there any way to do something like this? Can I do a has_many :through = master_group? Am I approaching this the wrong way? Thanks!

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