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• question about copy constructor

  - by lego69

  I have this class: class A { private: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); ~A(); void foo() const; }; and I have function which contains this row: A *pa1 = new A(a2); can somebody please explain what exactly is going on, when I call A(a2) compiler calls copy constructor or constructor, thanks in advance

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• name of class that manipulates the entities

  - by cyberguest

  hi, i have a general question regarding naming convention. if I separate the data and operations into two separate classes. one has the data elements (entity), the other class manipulates the entity class. what do we usually call that class that manipulates the entity class? (the entity I am referring to has nothing to do with any kind of entity framework) manager? controller? operator? manipulator? thanks in advance

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• How to simulate Func<T1, T2, TResult> in C++?

  - by Zach

  Hello all, In C#, I use Func to replace Factories. For example: class SqlDataFetcher { public Func<IConnection> CreateConnectionFunc; public void DoRead() { IConnection conn = CreateConnectionFunc(); // call the Func to retrieve a connection } } class Program { public void CreateConnection() { return new SqlConnection(); } public void Main() { SqlDataFetcher f = new SqlDataFetcher(); f.CreateConnectionFunc = this.CreateConnection; ... } } How can I simulate the code above in C++?

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• Calling a function when using <button> tag with jQuery Mobile

  - by u2sonderzug

  I already asked a similar question for buttons in tags, but I find that solution doesn't work using tags. So, if I am using a script that references jQuery Mobile I have the following line: <button id="buttonAnswer1" data-inline="true">Click me</button> How would I add a listener for when this button is clicked and lets say call the hello() function? i.e. <button id="buttonAnswer1" data-inline="true">Click me</button> <script> function hello(){ console.log("hello world"); } </script>

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• How to step inside NSManagedObject; access individual attributes.

  - by user300972

  NSManagedObject *entryObj = [self.fetchedResultsController objectAtIndexPath:indexPath]; entryObj consists of four String attributes. If I NSLog entryObj, I get the information I want. I cannot figure out how to access each of these properties individually. I read a similar post where the solution was to call "entity." I cannot figure out how to use "entity" to access a specific attribute. Any ideas? References? Tutorials? Thanks in advance.

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• why can not see my method if i implamented interface to normal class?

  - by Phsika

  i can not see MyLoad.TreeLoader(.... but why i can not see? i implemented iloader to TreeViewLoad. i should see TreeLoader why? namespace Rekursive { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { //treeView1.Nodes.Add("Test"); iloader MyLoad = new TreeViewLoad(); MyLoad.loader("test", treeView1, 1); // i can not see MyLoad.TreeLoader(.... but why i can not see? // i implemented iloader to TreeViewLoad. i should see TreeLoader why? //TreeViewLoad myloader = new TreeViewLoad(); } } interface iloader { void loader(string nodeName, TreeView myTre, int id); } class TreeViewLoad : iloader { public void TreeLoader(TreeView tre) { // i will call loader... } public void loader(string nodeName, TreeView myTre, int id) { myTre.Nodes.Add(nodeName + id.ToString()); if (id

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• Java inheritance question

  - by user247866

  So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = method-call();` // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void some-method(LIst<A> a) However, when I do: C c = new C(). c. some-method(b) I get an error that some-method is not applicable for the argument List, instead it's expecting to get List. Is there a good way to fix this problem? Many thanks!

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• How do I compare a string in an array to a string?

  - by user1641312

  EDIT: IT'S FIXED, THANKS FOR THE HELP! So basically I have an array of strings, a question and an answer public static String[][] triviaData = { {"Question2", "Answer1"}, {"Question2", "Answer2"}, {"Question3", "Answer3"}, }; And I am trying to make a method that validates an entered input, lets call the entered input enteredAnswer. enteredAnswer is stored as a String. I am trying to validate that the enteredAnswer is the same as the second index of the array. if (enteredAnswer.equalsIgnoreCase(triviaData[Config.CurrentQuestion][1])) { This is the code I tried, but I get the error "Cannot invoke equalsIgnoreCase(String) on the array type String[]" I am a beginner programmer so if you could help me out it would be highly appreciated. Thanks. enteredAnswer is stored as public String[] enteredAnswer;

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• .Htaccess & Wildcard Subdomains — Can't get other variables to work!

  - by Justin Scheetz

  It would be absolutely awesome if someone could help me out here. I have a domain, let's call it "example.com". I have wildcard subdomains setup and working great. The only problem is I can't get htaccess to see anything else like subdomain.example.com/profile/some_name/some_id_number/. In fact, I can type any garbage after the domain and it will still just show me the home screen. Here's what's in my htaccess file now: Options +FollowSymLinks Options +Indexes Options -Multiviews RewriteEngine On RewriteCond %{REQUEST_URI} !^/app/index.php RewriteCond %{HTTP_HOST} !^www\.example\.com RewriteCond %{HTTP_HOST} ^([^.]+)\.example\.com RewriteRule (.*) /app/index.php?user%1 [L] I can see why that wouldn't work yet, but I wanted to add something similar to the following: RewriteRule ^profile/([^/]+)/([^/]+) /app/index.php?page=profile&username=$1&user_id=$2 [nc] But it's not working at all. The server doesn't even really show signs that it's even seeing it there. Any ideas?

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• Use variables entered in login page usable in multiple pages?

  - by deception1

  I have a Login page that captures User input like this. MD5calc ss = new DBCon.MD5calc(); string gs = ss.CalculateMD5Hash(password.Password); int unitID = Convert.ToInt32(Unit_ID.Text); logBO.UnitID = unitID; logBO.UserID = User_name.Text; logBO.UserPass = gs; How would i make them assignable to any other page i created.My Common sense says that creating a static class would be enough,but will it?If i do create a static class where would i put it and how would i call it?I actually need those variable to use in my Sql Stored procedures.

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• EXC_BAD_ACCESS when returning a CGRect in iPhone

  - by pabloruiz55

  I have a class which must return a CGRect from one of its methods: -(CGRect)myRect { CGRect rect = CGRectMake(self.mySprite.position.x,self.mySprite.position.y,self.mySprite.textureRect.size.width, self.mySprite.textureRect.size.height); return rect; } I get an exc_bad_access as soon as i try to access the mySprite ivar. Thing is if i call it, the instance variable mySprite is full of garbage. BUT if i change the function to return void, self.mySprite does contain the correct data. -(void)myRect { CGRect rect = CGRectMake(self.mySprite.position.x,self.mySprite.position.y,self.mySprite.textureRect.size.width, self.mySprite.textureRect.size.height); return rect; } that does not crash when accessing mySprite...

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• How to store and retrieve file in mongoengine?

  - by Seiverence

  I am attempting to store and retrieve file within mongodb, but am having issues with the retrieval. class Animal(Document): genus = StringField() family = StringField() photo = FileField() def get_file(): marmot = Animal.objects(genus='Marmota').first() photo = marmot.photo.read() content_type = marmot.photo.content_type print marmot.family # Prints out "Sciuridae" print content_type # Gives me an error, as content_type is "None" def save_file(): marmot = Animal( genus='Marmota', family='Sciuridae') marmot_photo = open('marmot.jpg', 'r') marmot.photo = marmot_photo marmot.photo.content_type = 'image/jpeg' marmot.save() When I check mongodb, it appears the document does save after the save_file, but when I call get_file, it appears the content_type is "None"? Am I saving and retrieving the file correctly? If not, whats wrong with the code? NOTE: The issue appears only to occur in the Windows environment. When run on linux, it works fine... very confused.

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• Singleton Creation preference

  - by cwieland

  You can create singletons in a variety of ways. I am wondering which is better between these. +(ServerConnection*)shared{ static dispatch_once_t pred=0; __strong static id _sharedObject = nil; dispatch_once(&pred, ^{ _sharedObject = [[self alloc] init]; // or some other init method }); return _sharedObject; } I could see that this compiles down to something very fast. I would think that checking the predicate would be another function call. The other is: +(ServerConnection*)shared{ static ServerConnection* connection=nil; if (connection==nil) { connection=[[ServerConnection alloc] init]; } return connection; } Are there any major differences between the two? I know these are probably similar enough to not worry about it. But Just wondering.

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• jQuery - Set selected value of all dropdowns on page

  - by Tgibson

  Hello Frieds, I have another jQuery question. For a user control with lots of database activity, I would like to use jQuery to set the selected values of all of the dropdowns to their "current" value. I want to do this to make the page appear to have finished the database call. My jQuery skill is not the best, but I believe I need to use the pageLoad(). And since each dropdown is inside of a user control I can search for those dropdowns beginning with "usrControl" $('select[id ^="usrControl"'].each(function(){ var selectedValue = $(this).val() $(this).val(selectedValue) }); Something like this is what I have in mind. Thanks

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• How to make Eclipse compile with Java 1.5 in Mac OS X Leopard (10.5)?

  - by whiskeyspider

  I have been developing in Snow Leopard (10.6). I believe I have some Java6-only API features and I'd like to find these. I moved my project to Leopard (10.5) -- since Snow Leopard does not support Java 1.5 -- but I am so far unable to make Eclipse give compile errors for a Java API call which I know to have been added in 1.6. Here is what I have done: Project properties - Java Compiler - set everything to 1.5. Preferences - Java - Installed JREs - selected JVM 1.5.0. Project properties - Java Build Path - Libraries - says JRE System Library [JVM 1.5.0] What am I missing? Is there another way to find Java API calls added in 1.6 when using Eclipse in Snow Leopard? Thanks.

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• How to find distance between two geopoints in c using calculateDistance(const CWaypoint& wp)

  - by Harsha

  void getAllDataByPointer(string *pname,double *platitude, double *plongitude); void getAllDataByReference(string &pname,double &platitude, double &plongitude); double calculateDistance(const CWaypoint& wp); void print(int format); bool less(const CWaypoint& wp_right); CWaypoint add(const CWaypoint& wp_right); These are the functions I am using. I have the values as output but how to call the latitude values of two different cities so that I can use the following formula distance = ERADIUS * (acos(sin(latitude_1)*sin(latitude_2) + cos(latitude_1) * cos(latitude_2)*cos(longitude_2 - longitude_1)));

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• Accessing local variable doesn't improve performance

  - by NicMagnier

  The short version Why is this code: var index = (Math.floor(y / scale) * img.width + Math.floor(x / scale)) * 4; More performant than this one? var index = Math.floor(ref_index) * 4; The long version This week, the author of Impact js published an article about some rendering issue: http://www.phoboslab.org/log/2012/09/drawing-pixels-is-hard In the article there was the source of a function to scale an image by accessing pixels in the canvas. I wanted to suggest some traditional ways to optimize this kind of code so that the scaling would be shorter at loading time. But after testing it my result was most of the time worst that the original function. Guessing this was the JavaScript engine that was doing some smart optimization I tried to understand a bit more what was going on so I did a bunch of test. But my results are quite confusing and I would need some help to understand what's going on. I have a test page here: http://www.mx981.com/stuff/resize_bench/test.html jsPerf: http://jsperf.com/local-variable-due-to-the-scope-lookup To start the test, click the picture and the results will appear in the console. There are three different versions: The original code: for( var y = 0; y < heightScaled; y++ ) { for( var x = 0; x < widthScaled; x++ ) { var index = (Math.floor(y / scale) * img.width + Math.floor(x / scale)) * 4; var indexScaled = (y * widthScaled + x) * 4; scaledPixels.data[ indexScaled ] = origPixels.data[ index ]; scaledPixels.data[ indexScaled+1 ] = origPixels.data[ index+1 ]; scaledPixels.data[ indexScaled+2 ] = origPixels.data[ index+2 ]; scaledPixels.data[ indexScaled+3 ] = origPixels.data[ index+3 ]; } } jsPerf: http://jsperf.com/so-accessing-local-variable-doesn-t-improve-performance One of my attempt to optimize it: var ref_index = 0; var ref_indexScaled = 0 var ref_step = 1 / scale; for( var y = 0; y < heightScaled; y++ ) { for( var x = 0; x < widthScaled; x++ ) { var index = Math.floor(ref_index) * 4; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+1 ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+2 ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+3 ]; ref_index+= ref_step; } } jsPerf: http://jsperf.com/so-accessing-local-variable-doesn-t-improve-performance The same optimized code but with recalculating the index variable each time (Hybrid) var ref_index = 0; var ref_indexScaled = 0 var ref_step = 1 / scale; for( var y = 0; y < heightScaled; y++ ) { for( var x = 0; x < widthScaled; x++ ) { var index = (Math.floor(y / scale) * img.width + Math.floor(x / scale)) * 4; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+1 ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+2 ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+3 ]; ref_index+= ref_step; } } jsPerf: http://jsperf.com/so-accessing-local-variable-doesn-t-improve-performance The only difference in the two last one is the calculation of the 'index' variable. And to my surprise the optimized version is slower in most browsers (except opera). Results of personal testing (not the jsPerf tests): Opera Original: 8668ms Optimized: 932ms Hybrid: 8696ms Chrome Original: 139ms Optimized: 145ms Hybrid: 136ms Safari Original: 433ms Optimized: 853ms Hybrid: 451ms Firefox Original: 343ms Optimized: 422ms Hybrid: 350ms After digging around, it seems an usual good practice is to access mainly local variable due to the scope lookup. Because The optimized version only call one local variable it should be faster that the Hybrid code which call multiple variable and object in addition to the various operation involved. So why the "optimized" version is slower? I thought that it might be because some JavaScript engine don't optimize the Optimized version because it is not hot enough but after using --trace-opt in chrome, it seems all version are properly compiled by V8. At this point I am a bit clueless and wonder if somebody would know what is going on? I did also some more test cases in this page: http://www.mx981.com/stuff/resize_bench/index.html

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• private virtual function in derived class

  - by user1706047

  class base { public: virtual void doSomething() = 0; }; class derived : public base { **private:** virtual void doSomething(){cout<<"Derived fn"<<endl;} }; now if i do the following: base *b=new child; b->doSomething(); //it calls the derived class fn even if that is private. Question: 1.its able to call the derived class fn even if that is private.How is it possible? Now if i change the inheritance access specifier from public to protected/private then i get compilation error as "'type cast' : conversion from 'Derived *' to 'base *' exists, but is inaccessible" Notes: I am aware on the concepts of the inheritance access specifiers.So in second case as its derived private/protected, its inaccessible. But here it confuses me for the first question. Any input will be highly appreciated

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• Pushing to an array not working as expected

  - by Ross Attrill

  When I execute the code below, my array 'tasks' ends up with the same last row from the dbi call repeated for each row in the database. require 'dbi' require 'PP' dbh = DBI.connect('DBI:ODBC:Driver={SQL Server Native Client 10.0};Server=localhost,1433;Database=db;Uid=db;Pwd=mypass', 'db', 'mypass') sth = dbh.prepare('select * from TASK') sth.execute tasks = Array.new while row=sth.fetch do p row tasks.push(row) end pp(tasks) sth.finish So if I have two rows in my TASK table, then instead of getting this in the tasks array: [[1, "Task 1"], [2, "Task 2"]] I get this [[2, "Task 2"], [2, "Task 2"]] What am I doing wrong?

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• Qt QMainWindow at Close

  - by Cenoc

  Hey, this may seem like a very simple question, but I want to dump some data whenever the QMainWindow closes, so I used the following piece of code: QObject::connect(MainWindow.centralwidget, SIGNAL(destroyed()), this, SLOT(close())); but this doesnt seem to make it call close(). Am I doing this wrong? Isnt the centralwidget suppose to be destroyed? Or perhaps the application closes before close() can be called? Any other ways of doing it then? Thanks in advance!

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• Complex SQL queries (DELETE)?

  - by Joe

  Hello all, I'm working with three tables, and for simplicity's sake let's call them table A, B, and C. Both tables A and B have a column called id, as well as one other column, Aattribute and Battribute, respectively. Column c also has an id column, and two other columns which hold values for A.id and B.id. Now, in my code, I have easy access to values for both Aattribute and Battribute, and want to delete the row at C, so effectively I want to do something like this: DELETE FROM C WHERE aid=(SELECT id FROM A WHERE Aattribute='myvalue') AND bid=(SELECT id FROM B WHERE Battribute='myothervalue') But this obviously doesn't work. Is there any way to make a single complex query, or do I have to run three queries, where I first get the value of A.id using a SELECT with 'myvalue', then the same for B.id, then use those in the final query? [Edit: it's not letting me comment, so in response to the first comment on this: I tried the above query and it did not work, I figured it just wasn't syntactically correct. Using MS Access, for what it's worth. ]

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• jQuery extend $.fn and calling method syntax

  - by MBax

  I understand that you call a method like this when you are extending $.fn. ( $ == jQuery ) //$("div").myMethod(); $.fn.extend({ myMethod: function(){...} }); And like this when you extend the jQuery Object: //$.myMethod2(); $.extend({ myMethod2: function(){...} }); But I don't quite understand what the $() is doing here: $().functionName({ something: 'something' }).myMethod(); Does it have to do with the fact the method is being called including the function name? Thanks in advance and hope this makes sense.

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• Not quite nested inlines?

  - by Lynden Shields

  Not quite sure what to call this, it's not quite nested inlines, but is probably related. I have a 3 level hierarchy of objects, A one-to-many B one-to-many C. Therefore, every C implicitly also belongs to an A. class A(models.Model): stuff = models.CharField("Stuff", max_length=50) class B(models.Model): a = models.ForeignKey(A) class C(models.Model): b = models.ForeignKey(B) I would like all C's that belong to an A to be listed on the admin page for A in an in-line. They do not have to show which B they belong to on the same page. Is this possible or is it the same problem as nested inlines anyway? If it's possible, how do I do it? I'm using django 1.3

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• checkbox dynamic create for jquery

  - by user1397840

  How do i create multiple checkbox for jquery to identify it? example i have a html page with this is call new.html <div id =new> <input type=checkbox"></div> at create.html i want to use jquery to load multiple checkbox <div id=load> <div> $("#load).load(new.html) so if i use a for loop to loop 10times to create 10 checkbox, how do i identify each checkbox uniquely? for(var i = 0;i<10;i++){ $("#load).load(new.html)}

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• Associate a URL with a resource within my application

  - by Horace Loeb

  When I visit http://my-application.com/posts/1 in my browser, Rails knows I'm looking for the Post with id = 1. How can I get my application to do this internally? I.e., I'd like a function (call it associate_with_resource) that takes a string containing a URL as its input and outputs the associated resource. For example: >> associate_with_resource('http://my-application.com/posts/1') => #<Post id: 1, ... > (I'd like to be able to use associate_with_resource throughout my application though -- not only in the console)

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