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• Access of private field of another object in copy constructors - Really a problem?

  - by DR

  In my Java application I have some copy-constructors like this public MyClass(MyClass src) { this.field1 = src.field1; this.field2 = src.field2; this.field3 = src.field3; ... } Now Netbeans 6.9 warns about this and I wonder what is wrong with this code? My concerns: Using the getters might introduce unwanted side-effects. The new object might no longer be considered a copy of the original. If it is recommended using the getters, wouldn't it be more consistent if one would use setters for the new instance as well?

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• How to implement the API/SPI Pattern in Java?

  - by Adam Tannon

  I am creating a framework that exposes an API for developers to use: public interface MyAPI { public void doSomeStuff(); public int getWidgets(boolean hasRun); } All the developers should have to do is code their projects against these API methods. I also want them to be able to place different "drivers"/"API bindings" on the runtime classpath (the same way JDBC or SLF4J work) and have the API method calls (doSomeStuff(), etc.) operate on different 3rd party resources (files, servers, whatever). Thus the same code and API calls will map to operations on different resources depending on what driver/binding the runtime classpath sees (i.e. myapi-ftp, myapi-ssh, myapi-teleportation). How do I write (and package) an SPI that allows for such runtime binding, and then maps MyAPI calls to the correct (concrete) implementation? In other words, if myapi-ftp allows you to getWidgets(boolean) from an FTP server, how would I could this up (to make use of both the API and SPI)? Bonus points for concrete, working Java code example! Thanks in advance!

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• Simplest way to create a wrapper class around some strings for a WPF DataGrid?

  - by Joel

  I'm building a simple hex editor in C#, and I've decided to use each cell in a DataGrid to display a byte*. I know that DataGrid will take a list and display each object in the list as a row, and each of that object's properties as columns. I want to display rows of 16 bytes each, which will require a wrapper with 16 string properties. While doable, it's not the most elegant solution. Is there an easier way? I've already tried creating a wrapper around a public string array of size 16, but that doesn't seem to work. Thanks *The rational for this is that I can have spaces between each byte without having to strip them all out when I want to save my edited file. Also it seems like it'll be easier to label the rows and columns.

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• Why represent shopping carts and order invoices differently in a domain model?

  - by Todd

  I've built some shopping cart systems in the past, but I always designed them such that the final order invoice is just a shopping cart that has been marked as "purchased". All the logic for adding/removing/changing items in a cart is also the logic for the order. All data is stored in the same tables in the database. But it seems this is not the proper way to design an e-commerce site.. Can someone explain the benefit of separating the shopping cart from invoices in the domain model? It seems to me this would lead to a lot of duplicated code, an extra set of tables in the database, and make it harder to maintain in the event the system need to start accommodating more complicated orders (like specifying selected options for an item which may or may not change the price/availability/shipping time of the order). I'm assuming I just haven't seen the light, as every book and other example I see seems to separate these two seemingly similar concerns -- but I can't find any explanation as to the benefit of doing such! It's also the case in the systems that I design that changes are often made after the initial order is confirmed. It's not uncommon for items to be removed, replaced, or added afterwards (but prior to fulfillment).

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• Arguments to convince to switch from CVS to SVN

  - by ereOn

  Hi, The UNIX department of my company currently uses CVS as source-version control system. They use it in a very strange way: different repositories for development/testing/production code (for the same project), no one tags anything, weird directory architecture, and so on. The system has been set for ages but now, I have an opportunity to organize a meeting where I have to suggest changes. I'd like to make them change from CVS to SVN (Mercurial or Git might be even better, however I can't really recommand using a system I don't know well, and switching to SVN will already be a great step forward). I don't have much experience with CVS so I can't compare them efficiently: I just know it doesn't support atomic operations and that it is deprecated. What killer arguments would you use to convince my collegues to do the switch ? Thank you very much.

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• Using an interface as a constructor parameter in Java?

  - by aperson

  How would I be able to accomplish the following: public class testClass implements Interface { public testClass(Interface[] args) { } } So that I could declare Interface testObject = new testClass(new class1(4), new class2(5)); Where class1 and class2 are also classes that implement Interface. Also, once I accomplish this, how would I be able to refer to each individual parameter taken in to be used in testClass? Thanks :)

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• How can I use Object Oriented Javascript to interact with HTML Objects

  - by Steve

  I am very new to object orientated javascript, with experience writing gui's in python and java. I am trying to create html tables that I can place in locations throughout a webpage. Each html table would have two css layouts that control if it is selected or not. I can write all of the interaction if I only have one table. It gets confusing when I have multiple tables. I am wondering how to place these tables throughout a blank webpage and then access the tables individually. I think I am having trouble understanding how inheritance and hierarchy works in javascript/html. NOTE: I am not asking how to make a table. I am trying to dynamically create multiple tables and place them throughout a webpage. Then access their css independently and change it (move them to different locations or change the way the look, independently of the other tables).

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• C++ error message output format

  - by sub

  If I want to trigger an error in my interpreter I call this function: Error( ErrorType type, ErrorSeverity severity, const char* msg, int line ); However, with that I can only output Name error: Undefined variable in line 1 instead of Name error: Undefined variable 'someVariableName' in line 1 I'm working entirely with strings (except for the error messages as they all are constant at the moment), so sprintf won't work. What is the best way to create an efficient error function that can output a constant message combined with a string that describes which object, e.g.: a non-existing variable, triggered the error?

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• How to avoid nested functions when using AJAX?

  - by Fletcher Moore

  Sequential Asynchronous calls are gross. Is there a more readable solution? The problem is this is hard to follow: ajaxOne(function() { // do something ajaxTwo(function() { // do something ajaxThree() }); }); where the anonymous functions are callbacks that are called on server response. I'm using a third party API to make the AJAX calls, so I need a generic solution.

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• highlite text parts with jquery, best practice

  - by helle

  Hey guys, i have a list of items containig names. then i have a eventlistener, which ckecks for keypress event. if the user types i.g. an A all names starting with an A should be viewed with the A bold. so all starting As should be bold. what is the best way using jquery to highlite only a part of a string? thanks for your help

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• What should I use to increase performance. View/Query/Temporary Table

  - by Shantanu Gupta

  I want to know the performance of using Views, Temp Tables and Direct Queries Usage in a Stored Procedure. I have a table that gets created every time when a trigger gets fired. I know this trigger will be fired very rare and only once at the time of setup. Now I have to use that created table from triggers at many places for fetching data and I confirms it that no one make any changes in that table. i.e ReadOnly Table. I have to use this tables data along with multiple tables to join and fetch result for further queries say select * from triggertable By Using temp table select ... into #tx from triggertable join t2 join t3 and so on select a,b, c from #tx --do something select d,e,f from #tx ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. By Using Views create view viewname ( select ... from triggertable join t2 join t3 and so on ) select a,b, c from viewname --do something select d,e,f from viewname ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. This View can be used in other places as well. So I will be creating at database rather than at sp By Using Direct Query select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something . . --and so on --around 6-7 queries in a row in a stored procedure. Now I can create a view/temporary table/ directly query usage in all upcoming queries. What would be the best to use in this case.

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• When is C++ covariance the best solution?

  - by Neil Butterworth

  This question was asked here a few hours ago and made me realise that I have never actually used covariant return types in my own code. For those not sure what covariance is, it's allowing the return type of (typically) virtual functions to differ provided the types are part of the same inheritance hierarchy. For example: struct A { virtual ~A(); virtual A * f(); ... }; struct B : public A { virtual B * f(); ... }; The different return types of the two f() functions are said to be covariant. Older versions of C++ required the return types to be the same, so B would have to look like: struct B : public A { virtual A * f(); ... }; So, my question: Does anyone have a real-world example where covariant return types of virtual functions are required, or produce a superior solution to simply returning a base pointer or reference?

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• using partials in view helpers

  - by takeshin

  Creating custom Zend View helpers I often end up with something like: // logic here if ($condition) { $output = <<<EOS... } else { $output = <<<EOS... } or using switch. Then to eliminate this, I create setPartial(), getPartial() and htmlize() for using external .phtml's. This is not the best solution, because partials do not support doctype changing. Is there any better solution, than creating abstract class handling this common case? Are there any ready Zend solutions for this case? Separate view helper for each case? And where to put common code?

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• What is a mantainable way of saving "star rating" in a database?

  - by Montecristo

  I'll use the jQuery plugin for presenting the user with a nice interface The request is to display 5 stars, up to a total score of 10 (2 points per star). By now I thought about using 7/10 as a format for that value, but what if at some point in the future I'll receive a request like We would like to give users more choice, let's increase the total score to 20 (so that each star contributes with a maximum of 4 points) I'll end up with a table with mixed values for the "star rating" column: some will be like 7/10 while others will be like 14/20. Is it ok for you to have this difference in the database and deal with it in the logic layer to have it consistent? Or is preferred another way so that querying the table will not result in inconsistent results outside the application? Maybe floating point values could help me, is it better to store that value as a number less than or equal to one? So in each of the two examples the resulting value stored in the database would be 0,7, as a number, not a varchar, which can be queried also outside the application. What do you think?

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• Alternative to jQuery .data()?

  - by thebossman

  I'm a big fan of jQuery's .data() method, but I can't always use it. Often times I am rendering html templates that I pass via AJAX and I need to attach metadata to each of the elements in the template. For example: <ul> {% for item in itemlist %} <li metadata="{{ item.metadata }}">{{ item.name }}</li> {% endfor %} </ul> I know attaching attributes to store data is bad practice (and it might not even work in older versions of IE). What is the best practice? Is there a good alternative to this method?

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• Programmatically using tab character in .NET?

  - by Joan Venge

  Is there a way to use a tab character like a new line character inside Environment class, instead of using "\t"?

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• On Mac OS X, do you use the shipped python or your own?

  - by The MYYN

  On Tiger, I used a custom python installation to evaluate newer versions and I did not have any problems with that*. Now Snow Leopard is a little more up-to-date and by default ships with $ ls /System/Library/Frameworks/Python.framework/Versions/ 2.3 2.5 2.6 @Current What could be considered best practice? Using the python shipped with Mac OS X or a custom compiled version in, say $HOME. Are there any advantages/disadvantages using the one option over the other? My setup was fairly simple so far and looked like this: Custom compiled Python in $HOME and a $PATH that would look into $HOME/bin first, and subsequently would use my private Python version. Also $PYTHONPATH pointed to this local installation. This way, I did not need to sudo–install packages - virtualenv took care of the rest.

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• What is the best way to create a debugging web page for a computation in Java?

  - by Shooshpanchick

  I'm developing a website that uses some complex computations (NLP-related). My customer wants to have "debugging" webpages for some of these computations where he can run them with arbitrary input and see all the intermediate results that occur during computation. Before this request all of the computations were encapsulated in beans and intermediate results were logged into general log. What is the best way to capture all these results on Java level to render them as webpage?

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• Magic Method __set() on a Instantiated Object

  - by streetparade

  Ok i have a problem, sorry if i cant explaint it clear but the code speaks for its self. i have a class which generates objects from a given class name; Say we say the class is Modules: public function name($name) { $this->includeModule($name); try { $module = new ReflectionClass($name); $instance = $module->isInstantiable() ? $module->newInstance() : "Err"; $this->addDelegate($instance); } catch(Exception $e) { Modules::Name("Logger")->log($e->getMessage()); } return $this; } The AddDelegate Method: protected function addDelegate($delegate) { $this->aDelegates[] = $delegate; } The __call Method public function __call($methodName, $parameters) { $delegated = false; foreach ($this->aDelegates as $delegate) { if(class_exists(get_class($delegate))) { if(method_exists($delegate,$methodName)) { $method = new ReflectionMethod(get_class($delegate), $methodName); $function = array($delegate, $methodName); return call_user_func_array($function, $parameters); } } } The __get Method public function __get($property) { foreach($this->aDelegates as $delegate) { if ($delegate->$property !== false) { return $delegate->$property; } } } All this works fine expect the function __set public function __set($property,$value) { //print_r($this->aDelegates); foreach($this->aDelegates as $k=>$delegate) { //print_r($k); //print_r($delegate); if (property_exists($delegate, $property)) { $delegate->$property = $value; } } //$this->addDelegate($delegate); print_r($this->aDelegates); } class tester { public function __set($name,$value) { self::$module->name(self::$name)->__set($name,$value); } } Module::test("logger")->log("test"); // this logs, it works echo Module::test("logger")->path; //prints /home/bla/test/ this is also correct But i cant set any value to class log like this Module::tester("logger")->path ="/home/bla/test/log/"; The path property of class logger is public so its not a problem of protected or private property access. How can i solve this issue? I hope i could explain my problem clear.

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• C++ Iterator Pipelining Designs

  - by Kirakun

  Suppose we want to apply a series of transformations, int f1(int), int f2(int), int f3(int), to a list of objects. A naive way would be SourceContainer source; TempContainer1 temp1; transform(source.begin(), source.end(), back_inserter(temp1), f1); TempContainer2 temp2; transform(temp1.begin(), temp1.end(), back_inserter(temp2), f2); TargetContainer target; transform(temp2.begin(), temp2.end(), back_inserter(target), f3); This first solution is not optimal because of the extra space requirement with temp1 and temp2. So, let's get smarter with this: int f123(int n) { return f3(f2(f1(n))); } ... SourceContainer source; TargetContainer target; transform(source.begin(), source.end(), back_inserter(target), f123); This second solution is much better because not only the code is simpler but more importantly there is less space requirement without the intermediate calculations. However, the composition f123 must be determined at compile time and thus is fixed at run time. How would I try to do this efficiently if the composition is to be determined at run time? For example, if this code was in a RPC service and the actual composition--which can be any permutation of f1, f2, and f3--is based on arguments from the RPC call.

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• C# Class Factories

  - by Andy

  I have a class called Foo that has a function that looks like the following List<Bar> LoadData(); Both Foo and Bar are in a library that I want to reuse in other projects. Now I am working on a new project and I want to subclass Bar. Let's call it NewBar. What is a simple and flexible way to get Foo.LoadData to return a list of NewBar? I think that a factory is needed or perhaps just a delegate function. Can anyone provide an example? Thanks, Andy

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• using ref to view error

  - by Avram

  Hello. I working now on firm that using ref in every function. The reason, is to catch errors. There example : //return true if the read is success //otherwise writing to the error ,the problem bool ReadFile(ref string error) Question: How do you catching errors? Using ref,exceptions or other way?

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• Why is short project lifetime and other situation-specific reasons used to excuse crappy code? [clos

  - by sharptooth

  Every now and then (including on SO) people say things implying that "if the project is short lived you can leave obvious defects there" or "that memory leak only accounts for 100 bytes per whole program lifetime and could be left". Now in my practice I always reuse company-owned code to the greatest extent I can. Like if I need something and I can find it in the company codebase I take it from there and reuse or adapt. This means that any crappy code will be reused as well and I might notice or not notice defects therein. So the defect in some "test we only need for a month" can slip into a proram we ship to customers. And a leak that "only accounted for 100 bytes per lifetime" now could account for 100 bytes 10 times per second in a server application intended to run for months. That's why I don't understand why excuses like that are offered. Is our compamy the only one having a source control? Or are we the only company that requires writing human-readable code? Could anyone shed a light on why people seriously offer such excuses?

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• Securing input of private / protected methods?

  - by ts

  Hello, normally, all sane developers are trying to secure input of all public methods (casting to proper types, validating, sanitizing etc.) My question is: are you in your code validating also parameters passed to protected / private methods? In my opinion it is not necessary, if you securize properly parameters of public methods and return values from outside (other classes, db, user input etc...). But I am constantly facing frameworks and apps (ie. prestashop to name one) where validation is often repeated in method call, in method body and once again for securize returned value - which, I think, is creating performace overhead and is also a sign of bad design.

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• Why is not advisable to use goto frequently? [closed]

  - by Babiker

  Possible Duplicate: GOTO still considered harmful? I have read articles that advise on refraining from using the goto operator frequently, but never told why. I have googled this for ever and can't really find anything.

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