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  • Simple Scala syntax - trying to define "==" operator - what am I missing?

    - by Alex R
    While experimenting with some stuff on the REPL, I got to a point where I needed something like this: scala class A(x:Int) { println(x); def ==(a:A) : Boolean = { this.x == a.x; } } Just a simple class with an "==" operator. Why doesn't it work??? Here's the result: :10: error: type mismatch; found : A required: ?{val x: ?} Note that implicit conversions are not applicable because they are ambiguous: both method any2ArrowAssoc in object Predef of type [A](x: A)ArrowAssoc[A] and method any2Ensuring in object Predef of type [A](x: A)Ensuring[A] are possible conversion functions from A to ?{val x: ?} class A(x:Int) { println(x); def ==(a:A) : Boolean = { this.x == a.x; } } ^ This is scala 2.8 RC1. Thanks

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  • Can I improve performance by refactoring SQL commands into classes?

    - by Matthew Jones
    Currently, my entire website does updating from SQL parameterized queries. It works, we've had no problems with it, but it can occasionally be very slow. I was wondering if it makes sense to refactor some of these SQL commands into classes so that we would not have to hit the database so often. I understand hitting the database is generally the slowest part of any web application For example, say we have a class structure like this: Project (comprised of) Tasks (comprised of) Assignments Where Project, Task, and Assignment are classes. At certain points in the site you are only working on one project at a time, and so creating a Project class and passing it among pages (using Session, Profile, something else) might make sense. I imagine this class would have a Save() method to save value changes. Does it make sense to invest the time into doing this? Under what conditions might it be worth it?

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  • Use SQL query to populate property in nHibernate mapping file

    - by brainimus
    I have an object which contains a property that is the result of an SQL statement. How do I add the SQL statement to my nHibernate mapping file? Example Object: public class Library{ public int BookCount { get; set; } } Example Mapping File: <hibernate-mapping> <class name="Library" table="Libraries"> <property name="BookCount" type="int"> <- This is where I want the SQL query to populate the value. -> </class> </hibernate-mapping> Example SQL Query: SELECT COUNT(*) FROM BOOKS WHERE BOOKS.LIBRARY_ID = LIBRARIES.ID

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  • C++, create an instance from a static method

    - by Manux
    Hello, let's say I want my users to use only one class, say SpecialData. Now, this data class would have many methods, and depending on the type of data, the methods do different things, internally, but return externally similar results. Therefore my wanting to have one "public" class and other "private", child classes that would change the behavior of methods, etc... It would be amazingly more simple for some types of data that need to be built to do something like this: SpecialData& sm = SpecialData::new_supermatrix(); and new_supermatrix() would return a SuperMatrix instance, which inherits from most behaviors of SpecialData. my header: static SpecialData& new_supermatrix(); my cpp: SpecialData& SpecialData::new_supermatrix()(){ return SuperMatrix(MATRIX_DEFAULT_MAGNITUDE,1000,1239,FLOAT32,etc...); } The problem is, I get this error, which is probably logical due to the circumstances: invalid initialization of non-const reference of type ‘SpecialData&’ from a temporary of type ‘SpecialData’ So, any ideas?

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  • Add Attribute (System.Attribute variety) to .aspx page - not the code-behind

    - by Macho Matt
    I am creating a custom Attribute (extending System.Attribute). I know I can put it on another class easily enough by doing the following. [MattsAttribute] public class SomeClassWhichIsACodeBehind { However, I need to be able to test this attribute easily, and putting it in the code-behind would cause a lot of extra effort to get it deployed to an environment which would respond to the behavior of attribute. What I would like to do: declaratively apply this attribute to the .aspx page itself (which is really just another class that inherits from the code-behind). Is this possible? If so, what is the proper syntax for doing this?

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  • syntax error, unexpected '.', expecting ')'

    - by Jonathan
    Hi, I've got a problem when I'm calling a static var from another class. I get this pretty syntax error where php is unexpected the '.' Here is where I'm calling it : private $aLien = array( "menu1" => array("Accueil","statique/".Variable_init::$langue."/accueil.html",0,0), //This line "menu2" => array("Infos Pratiques","statique/".Variable_init::$langue."/info.html",0,0), "menu3" => array("Faire une réservation","statique/".Variable_init::$langue."/reserver.html",0,0), "menu4" => array("Pour Nous Joindre","statique/".Variable_init::$langue."/nousJoindre.html",0,0), "menu5" => array("Plan du site","statique/".Variable_init::$langue."/plansite.html",0,0) ); And here is my static var declaration from another class: class Variable_init implements iVariable_init{ public static $langue; public static $id_choix; public static $id_contenu;

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  • iPhone objective-c autoreleasing leaking

    - by okami
    I do this: NSString *fullpath = [[NSBundle mainBundle] pathForResource:@"text_file" ofType:@"txt"]; Why the following message appear? Is my code leaking? 2010-03-31 13:44:18.649 MJIPhone[2175:207] *** _NSAutoreleaseNoPool(): Object 0x3909ba0 of class NSPathStore2 autoreleased with no pool in place - just leaking Stack: (0x1656bf 0xc80d0 0xcf2ad 0xcee0e 0xd3327 0x2482 0x2426) 2010-03-31 13:44:18.653 MJIPhone[2175:207] *** _NSAutoreleaseNoPool(): Object 0x390b0b0 of class NSPathStore2 autoreleased with no pool in place - just leaking Stack: (0x1656bf 0xc80d0 0xc7159 0xd0c6f 0xd3421 0x2482 0x2426) 2010-03-31 13:44:18.672 MJIPhone[2175:207] *** _NSAutoreleaseNoPool(): Object 0x390d140 of class NSCFString autoreleased with no pool in place - just leaking Stack: (0x1656bf 0xc6e62 0xcec1b 0xd4386 0x24ac 0x2426)

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  • Optional parameters for interfaces

    - by bryanjonker
    Using c# 4.0 -- building an interface and a class that implements the interface. I want to declare an optional parameter in the interface and have it be reflected in the class. So, I have the following: public interface IFoo { void Bar(int i, int j=0); } public class Foo { void Bar(int i, int j=0) { // do stuff } } This compiles, but it doesn't look right. The interface needs to have the optional parameters, because otherwise it doesn't reflect correctly in the interface method signature. Should I skip the optional parameter and just use a nullable type? Or will this work as intended with no side effects or consequences?

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  • Showing current value in DB in a drop down box

    - by user195257
    Hello, this is my code which populates a drop down menu, all working perfectly, but when editing a database record, i want the first value in the drop down to be what is currently in the database, how would i do this? <li class="odd"><label class="field-title">Background <em>*</em>:</label> <label><select class="txtbox-middle" name="background" /> <?php $bgResult = mysql_query("SELECT * FROM `backgrounds`"); while($bgRow = mysql_fetch_array($bgResult)){ echo '<option value="'.$bgRow['name'].'">'.$bgRow['name'].'</option>'; } ?> </select></li>

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  • Wrapping Multiple Elements (jQuery)

    - by Nimbuz
    I've this piece of HTML: div.content div.one content div.two content div.three content I want to add two divs on top and bottom and wrap one div around it so it becomes: div.top div.wrapper div.content div.one content div.two content div.three content div.bottom I'm aware of the several wrap selectors (innerWrap, wrapAll etc..) but I'm not sure how to wrap 2 divs. The following jQuery might work, but is there a better way to write it? $('content').wrap('<div class="wrapper"></div'); $('.wrapper').before('<div class="top"></div>'); $('.wrapper').after('<div class="bottom"></div>');

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  • inheritance problem OOP extend

    - by hsmit
    If a Father is a Parent and a Parent is a Person and a Person has a Father I create the following: class Person{ Father father; } class Parent extends Person{} class Father extends Parent{} Instances: Person p1 = new Person(); Person p2 = new Person(); p1.father = p2; //father is of the type Father This doesn't work... Now try casting:: Person p1 = new Person(); Person p2 = new Person(); p1.father = (Father)p2; This doesn't work either. What does work for this case?

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  • What is this Design Pattern?

    - by Can't Tell
    I read the Wikipedia articles on FactoryMethod and AbstractFactory but the following code doesn't seem to fit anywhere. Can someone explain to me what the following pattern is or if it is an anti-pattern? interace PaymentGateway{ void makePayment(); } class PaypalPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class AuthorizeNetPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class PaymentGatewayFacotry{ PaymentGateway createPaymentGateway(int gatewayId) { if(gatewayId == 1) return PaypalPaymentGateway(); else if(gatewayId == 2) return AuthorizeNetPaymentGateway(); } } Let's say the user selects the payment method using a radio button on an html page and the gatewayId is derived from the radio button value. I have seen code like this and thought it was the AbstractFactory pattern but after reading the Wikipedia article, I'm having doubts.

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  • When to trash hashmap contents to avoid performance degradation?

    - by Jack
    Hello, I'm woking on Java with a large (millions) hashmap that is actually built with a capacity of 10.000.000 and a load factor of .75 and it's used to cache some values since cached values become useless with time (not accessed anymore) but I can't remove useless ones while on the way I would like to entirely empty the cache when its performance starts to degrade. How can I decide when it's good to do it? For example, with 10 millions capacity and .75 should I empty it when it reaches 7.5 millions of elements? Because I tried various threshold values but I would like to have an analytic one. I've already tested the fact that emping it when it's quite full is a boost for perfomance (first 2-3 algorithm iterations after the wipe just fill it back, then it starts running faster than before the wipe) Thanks

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  • Getting error in integrating Contacts APIs in Android 1.6 and 2.0

    - by dhaiwat
    Hi All, I have seen the BusinessCard example provide in Android examples. I am using ContactAccessor abstract class to seperate out the SDK versions. My code is running fine for 2.0 onwards, but when I am trying to build the code in Adnroid 1.6 I am getting the following errors: Build.VERSION_CODES.ECLAIR is not resolved. Getting errors in the whole class in which I have used Contacts APIs from 2.0 (say in class ContactAccessorSdk5.java). How to resolve these issues? I want to run my App on both the versions. Please help me. Regards, Dhaiwat Bhavsar.

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  • Boost singleton and undefined reference

    - by Ockonal
    Hello, I globally use singleton pattern in my project. To make it easier - boost::singleton. Current project uses Ogre3d library for rendering. Here is some class: class GraphicSystem : public singleton<GraphicSystem> { private: Ogre::RenderWindow *mWindow; public: Ogre::RenderWindow *getWindow() const { return mWindow; } }; In GraphicSystem constructor I fill the mWindow value: mWindow = mRoot->createRenderWindow(...); I cheked it, everything makes normally. So, now I have to use handler for the window in input system (to get window handle). Somewhere else in another class: Ogre::RenderWindow *temp = GraphicSystem::get_mutable_instance().getWindow(); GraphicSystem::get_mutable_instance().getWindow()->getCustomAttribute("WINDOW", &mWindowHandle); temp is 0x00, and there is segfault at last line (getting custon attribute). I can't understand, why does singleton returns undefined pointer for the window. All another singleton-based classes work well.

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  • override the operator overloading in C++ ?

    - by stdnoit
    helo guys i have class call Complex I did operator overloading like such Complex c = a + b; // where a and b are object of Complex class which basically is operator+(Complex& that); but I dont know how to say for example double c = a + 10; //where a is object of Complex class but 10 is integer / double I did define typecasting for a to be double get my IDE says that there are too many operands + and it somehow complains for not being able to "understand" the + it has to be in this format though double c = a + 10; thanks

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  • Connecting data to a GUI - OOP

    - by tau
    I have an application with several graphs and tables on it. I worked fast and just made classes like Graph and Table that each contained a request object (pseudo-code): class Graph { private request; public function setDateRange(dateRange) { request.setDateRange(dateRange); } public function refresh() { request.getData(function() { //refresh the display }); } } Upon a GUI event (say, someone changes the date range dropdown), I'd just call the setters on the Graph instance and then refresh it. Well, when I added other GUI elements like tables and whatnot, they all basically had similar methods (setDateRange and other things common to the request). What are some more elegant OOP ways of doing this? The application is very simple and I don't want to over-architect it, but I also don't want to have a bunch of classes with basically the same methods that are just routing to a request object. I also don't want to set up each GUI class as inheriting from the request class, but I'm open to any ideas really.

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  • Polymorphic classes in templates

    - by soxarered
    Let's say we have a class hierarchy where we have a generic Animal class, which has several classes directly inherit from it (such as Dog, Cat, Horse, etc..). When using templates on this inheritance hierarchy, is it legal to just use SomeTemplateClass<Animal> and then shove in Dogs and Cats and Horses into this templated object? For example, assume we have a templated Stack class, where we want to host all sorts of animals. Can I simply state Stack<Animal> s; Dog d; s.push(d); Cat c; s.push(c);

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  • Why is JSON outputting out of order?

    - by dcp3450
    I'm am trying to get a list of weather information for 8 locations. I'm using a weather API that accepts longitude and latitude and spits back json output with the weather info for that location. I feed the coords in order 0-7 but when json processes the data it comes back in a seemingly random order. I assume it's because some process faster than others and json is outputing what it gets back as it gets it. The output is correct, only the order is wrong. var loc = null; var body = ""; var campuses = new Array(8); campuses[0] = "34.47242,-84.42489,1"; campuses[1] = "33.81488,-84.62048,2"; campuses[2] = "34.27502,-84.46976,3"; campuses[3] = "33.92987,-84.55065,4"; campuses[4] = "34.03433,-84.46723,5"; campuses[5] = "34.08362,-84.67115,6"; campuses[6] = "33.91124,-84.82634,7"; campuses[7] = "34.10409,-84.51804,8"; function getWeather(campusArray) { body += '<p class="topTitle">Campus Weather</p>'; var cSplit = new Array(); cSplit = campusArray.split(','); var loc = "http://www.worldweatheronline.com/feed/weather.ashx?q="+cSplit[0]+","+cSplit[1]+"&format=json&num_of_days=2&key=0a05fff921162948110401&callback=?"; $('#content').html('asdf'); $.getJSON(loc,function(js) { var data = js.data; var humidity = data.current_condition[0].humidity; var tempF = data.current_condition[0].temp_F; var iconDESC = data.current_condition[0].weatherDesc[0].value; var iconURL = data.current_condition[0].weatherIconUrl[0].value; var windDir = data.current_condition[0].winddir16Point; var windSpeed = data.current_condition[0].windspeedMiles; var tempMaxF = data.weather[0].tempMaxF; var tempMinF = data.weather[0].tempMinF; body += '<p class="title">'+cSplit[2]+'</p>'+ '<span class="body">'+tempF+ ' '+windSpeed+ '<img src="'+iconURL+'" /></span>'; $('#content').html(body); }); } getWeather(campuses[0]); getWeather(campuses[1]); getWeather(campuses[2]); getWeather(campuses[3]); getWeather(campuses[4]); getWeather(campuses[5]); getWeather(campuses[6]); getWeather(campuses[7]); I have also tried it as $.ajax var loc = null; var body = ""; var campuses = new Array(8); campuses[0] = "34.47242,-84.42489,1"; campuses[1] = "33.81488,-84.62048,2"; campuses[2] = "34.27502,-84.46976,3"; campuses[3] = "33.92987,-84.55065,4"; campuses[4] = "34.03433,-84.46723,5"; campuses[5] = "34.08362,-84.67115,6"; campuses[6] = "33.91124,-84.82634,7"; campuses[7] = "34.10409,-84.51804,8"; function getWeather(campusArray) { body += '<p class="topTitle">Campus Weather</p>'; var cSplit = new Array(); cSplit = campusArray.split(','); var loc = "http://www.worldweatheronline.com/feed/weather.ashx?q="+cSplit[0]+","+cSplit[1]+"&format=json&num_of_days=2&key=0a05fff921162948110401&callback=?"; $.ajax({ url: loc, async: true, dataType: "json", success: function(js) { var data = js.data; var humidity = data.current_condition[0].humidity; var tempF = data.current_condition[0].temp_F; var iconDESC = data.current_condition[0].weatherDesc[0].value; var iconURL = data.current_condition[0].weatherIconUrl[0].value; var windDir = data.current_condition[0].winddir16Point; var windSpeed = data.current_condition[0].windspeedMiles; var tempMaxF = data.weather[0].tempMaxF; var tempMinF = data.weather[0].tempMinF; body += '<p class="title">'+cSplit[2]+'</p>'+ '<span class="body">'+tempF+ ' '+windSpeed+ '<img src="'+iconURL+'" /></span>'; $('#content').html(body); } }); } getWeather(campuses[0]); getWeather(campuses[1]); getWeather(campuses[2]); getWeather(campuses[3]); getWeather(campuses[4]); getWeather(campuses[5]); getWeather(campuses[6]); getWeather(campuses[7]); EDIT: example of json output: { "data": { "current_condition": [ {"cloudcover": "100", "humidity": "93", "observation_time": "04:04 PM", "precipMM": "0.0", "pressure": "1009", "temp_C": "2", "temp_F": "36", "visibility": "8", "weatherCode": "116", "weatherDesc": [ {"value": "Mist" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0006_mist.png" } ], "winddir16Point": "WNW", "winddirDegree": "290", "windspeedKmph": "7", "windspeedMiles": "4" } ], "request": [ {"query": "Lat 34.47 and Lon -84.42", "type": "LatLon" } ], "weather": [ {"date": "2011-01-06", "precipMM": "9.3", "tempMaxC": "7", "tempMaxF": "45", "tempMinC": "2", "tempMinF": "35", "weatherCode": "113", "weatherDesc": [ {"value": "Sunny" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0001_sunny.png" } ], "winddir16Point": "WNW", "winddirDegree": "293", "winddirection": "WNW", "windspeedKmph": "20", "windspeedMiles": "13" }, {"date": "2011-01-07", "precipMM": "0.0", "tempMaxC": "6", "tempMaxF": "44", "tempMinC": "0", "tempMinF": "31", "weatherCode": "116", "weatherDesc": [ {"value": "Partly Cloudy" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0002_sunny_intervals.png" } ], "winddir16Point": "WNW", "winddirDegree": "286", "winddirection": "WNW", "windspeedKmph": "25", "windspeedMiles": "16" } ] }}

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  • Any way to set or overwrite the __line__ and __file__ metadata?

    - by charles.merriam
    I'm writing some code that needs to change function signatures. Right now, I'm using Simionato's FunctionMaker class, which uses the (hacky) inspect module, and does a compile. Unfortunately, this still loses the line and file metadata. Does anyone know: If it is possible to overwrite these values in some odd way? If hacking up a class with a complex getattribute() to intercept the values and also try to make the class looks like a function is any more possible than a moose with a flying nun hat? Is there an alternative to the (hacky) inspect module? PEP 362 is dead dead dead? I know decorators and cPickle users fight with this. What other situations is the read only metadata in people's way? I appreciate any insights. Thank you.

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  • Can I improve performance by refactoring SQL commands into C# classes?

    - by Matthew Jones
    Currently, my entire website does updating from SQL parameterized queries. It works, we've had no problems with it, but it can occasionally be very slow. I was wondering if it makes sense to refactor some of these SQL commands into classes so that we would not have to hit the database so often. I understand hitting the database is generally the slowest part of any web application For example, say we have a class structure like this: Project (comprised of) Tasks (comprised of) Assignments Where Project, Task, and Assignment are classes. At certain points in the site you are only working on one project at a time, and so creating a Project class and passing it among pages (using Session, Profile, something else) might make sense. I imagine this class would have a Save() method to save value changes. Does it make sense to invest the time into doing this? Under what conditions might it be worth it?

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  • Best indexing strategy for several varchar columns in Postgres

    - by Corey
    I have a table with 10 columns that need to be searchable (the table itself has about 20 columns). So the user will enter query criteria for at least one of the columns but possibly all ten. All non-empty criteria is then put into an AND condition Suppose the user provided non-empty criteria for column1 and column4 and column8 the query would be: select * from the_table where column1 like '%column1_query%' and column4 like '%column4_query%' and column8 like '%column8_query%' So my question is: am I better off creating 1 index with 10 columns? 10 indexes with 1 column each? Or do I need to find out what sets of columns are queried together frequently and create indexes for them (an index on cols 1,4 and 8 in the case above). If my understanding is correct a single index of 10 columns would only work effectively if all 10 columns are in the condition. Open to any suggestions here, additionally the rowcount of the table is only expected to be around 20-30K rows but I want to make sure any and all searches on the table are fast. Thanks!

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  • Code won't exit foreach block

    - by Matt
    I've got the following C# code segment that takes a list, finds objects that are ready to update, then shoves them into a temp list, deletes from the main list, and then goes on its merry way. My issue is that the foreach block, which cycles through my main list, won't exit. TempLog.Clear(); //Ensure TempLog is empty foreach (CLogger ready in PlayerLog) { if (ready.UpdateReady == true) // Record is ready to be updated in database { TempLog.Add(ready); // Add record to templog PlayerLog.Remove(ready); // Remove from playerlog } } <---- Never reaches this point if (TempLog.Count > 0) // Just check that templog isn't empty { new Thread(Update).Start(); // Run update code } I've put heaps of debugging in, and I can watch PlayerLog start at 1, TempLog at 0, then it enters the foreach loop, picks up that the record UpdateReady flag is on, TempLog goes to 1, PlayerLog goes to 0, then it just stops.. No errors, just stops.. Thanks for the help :)

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  • mysql conditional query - complicated!

    - by emre
    i want to get distinct values for a field, let say: field1... ok this needs a query like: "select distint(field1) from table" however for some records, field1 is empty and there is another column that is an alternative to field1, which is field2. now; for the records where field1 is empty i need to use the value of field2. i think i need sort of a conditional select statement with if control something like: "select distinct( (if(field1!='') field1 else field2) ) from table" but i have no idea on how to write it. any help is appricated...

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