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  • Lazy loading? Better avoiding it?

    - by Charlie Pigarelli
    I just read about this design pattern: Lazy Load. And, since in the application i'm working on i have all the classes in one folder, i was wondering if this pattern could just make me avoiding the include() function for every class. I mean: It's nice to know that if i forgot to include a class, PHP, before falling into an error, trough an __autoload() function try to get it. But is it fine enough to just don't care about including classes and let PHP do it by your own every time? Or we should write __autoload() just in case it is needed?

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  • Do you ever make a code change and just test rather than trying to fully understand the change you'v

    - by Clay Nichols
    I'm working in a 12 year old code base which I have been the only developer on. There are times that I'll make a a very small change based on an intuition (or quantum leap in logic ;-). Usually I try to deconstruct that change and make sure I read thoroughly the code. However sometimes, (more and more these days) I just test and make sure it had the effect I wanted. (I'm a pretty thorough tester and would test even if I read the code). This works for me and we have surprisingly (compared to most software I see) few bugs escape into the wild. But what I'm wondering is whether this is just the "art" side of coding. Yes, in an ideal world you would exhaustively read every bit of code that your change modified, but I in practice, if you're confident that it only affects a small section of code, is this a common practice? I can obviously see where this would be a disastrous approach in the hands of a poor programmer. But then, I've seen programmers who ostensibly are reading the code and break stuff left and right (in their own code based which only they have been working on).

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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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  • How to face observable object containing an observable field

    - by iseek
    Hello, I need a hint concerning MVC and Observer-Pattern. For example a model contains the classes "Address" and "Person". The Address class contains the fields street:String, zipcode:String, location:String. Whereas the Person class contains the fields name:String, firstName:String, address:Address. My approach so far looks something like this: Both, Address and Person are observable. If one of their setters is being called, I validate whether the current value and new value differ. Only in this case an update event is fired. The event contains the source, the name of the changed field, the old and the new value. The class for the view contains text fields to display and edit the information of a person: name, firstname, street, zipcode, location. It knows the Person model and is an subscribed observer for the person. So it gets the update events from the person object. My questions concerns the address field from type Address in the person class, since an address is observable on its own. If the view gets an update event from person when a new address has been set, I can update all of the address related fields in the view. But what if a field of the address changes? Should the view also register for update events from the address? Any hints about common design approaches would be appreciated. Greetings.

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  • why copy and paste codes is dangerous

    - by Yigang Wu
    sometimes, my boss will complain us why we need so long time to implement a feature, actually, the feature has been implemented in other AP before, you just need to copy and paste codes from there. The cost should be low. It's really a hard question, because copy and paste codes is not a easy thing from my point. Do you have any good reason to explain your boss who doesn't know technology?

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  • read files from directory and filter files from Java

    - by Adnan
    The following codes goes through all directories and sub-directories and outputs just .java files; import java.io.File; public class DirectoryReader { private static String extension = "none"; private static String fileName; public static void main(String[] args ){ String dir = "C:/tmp"; File aFile = new File(dir); ReadDirectory(aFile); } private static void ReadDirectory(File aFile) { File[] listOfFiles = aFile.listFiles(); if (aFile.isDirectory()) { listOfFiles = aFile.listFiles(); if(listOfFiles!=null) { for(int i=0; i < listOfFiles.length; i++ ) { if (listOfFiles[i].isFile()) { fileName = listOfFiles[i].toString(); int dotPos = fileName.lastIndexOf("."); if (dotPos > 0) { extension = fileName.substring(dotPos); } if (extension.equals(".java")) { System.out.println("FILE:" + listOfFiles[i] ); } } if(listOfFiles[i].isDirectory()) { ReadDirectory(listOfFiles[i]); } } } } } } Is this efficient? What could be done to increase the speed? All ideas are welcome.

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  • Continuous integration with multiple branch development

    - by ryanprayogo
    In the project that I'm working on, we are using SVN with 'Stable Trunk' strategy. What that means is that for each bug that is found, QA opens a bug ticket and assigns it to a developer. Then, a developer fixes that bug and checks it in a branch (off trunk, let's call this the bug branch) and that branch will only contain fixes for that particular bug ticket When we decided to do a release, for each bug fixes that we want to release to the customer, a developer will merge all the fixes from several bug branch to trunk and proceed with the normal QA cycle. The problem is that we use trunk as the codebase for our CI job (Hudson, specifically), and therefore, for all commits to the bug branch, it will miss the daily build until it gets merged to trunk when we decided to release the new version of the software. Obviously, that defeats the purpose of having CI. What is the proper way to fix this issue?

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  • Is it good practice to initialize array in C/C++?

    - by sand
    I recently encountered a case where I need to compare two files (golden and expected) for verification of test results and even though the data written to both the files were same, the files does not match. On further investigation, I found that there is a structure which contains some integers and a char array of 64 bytes, and not all the bytes of char array were getting used in most of the cases and unused fields from the array contain random data and that was causing the mismatch. This brought me ask the question whether it is good practice to initialize the array in C/C++ as well, as it is done in Java?

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  • Why is 'virtual' optional for overridden methods in derived classes?

    - by squelart
    When a method is declared as virtual in a class, its overrides in derived classes are automatically considered virtual as well, and the C++ language makes this keyword virtual optional in this case: class Base { virtual void f(); }; class Derived : public Base { void f(); // 'virtual' is optional but implied. }; My question is: What is the rationale for making virtual optional? I know that it is not absolutely necessary for the compiler to be told that, but I would think that developers would benefit if such a constraint was enforced by the compiler. E.g., sometimes when I read others' code I wonder if a method is virtual and I have to track down its superclasses to determine that. And some coding standards (Google) make it a 'must' to put the virtual keyword in all subclasses.

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  • Creating an interface and swappable implementations in python

    - by Blankman
    Hi, Would it be possible to create a class interface in python and various implementations of the interface. Example: I want to create a class for pop3 access (and all methods etc.). If I go with a commercial component, I want to wrap it to adhere to a contract. In the future, if I want to use another component or code my own, I want to be able to swap things out and not have things very tightly coupled. Possible? I'm new to python.

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  • How should I handle expected errors? eg. "username already exists"

    - by Pheter
    I am struggling to understand how I should design the error handling parts of my code. I recently asked a similar question about how I should go about returning server error codes to the user, eg. 404 errors. I learnt that I should handle the error from within the current part of the application; seem's simple enough. However, what should I do when I can't handle the error from the current link in the chain? For example, I may have a class that is used to manage authentication. One of it's methods could be createUser($username, $password). Within that function, I need to determine if the username already exists. If this is true, how should I alert the calling code about this? Returning null instead of a user object is one way. But how do I then know what caused the error? How should I handle errors in such a way that calling code can easily find out what caused the error? Is there a design pattern commonly used for this kind of situation?

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  • 'goto' usage

    - by Landon
    I've long been under the impression that 'goto' should never be used if possible. While perusing libavcodec (which is written in C) the other day, I noticed multiple uses of it. Is it ever advantageous to use 'goto' in a language that supports loops and functions? If so, why?

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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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  • One class per file rule in .NET?

    - by Joan Venge
    I follow this rule but some of my colleagues disagree with it and argue that if a class is smaller it can be left in the same file with other class(es). Another argument I hear all the time is "Even Microsoft don't do this, so why should we?" What's the general consensus on this? Are there cases where this should be avoided?

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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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  • Beginner Design pattern question (Web Services involved)

    - by zombie
    Hi all ! I am a noob to web services world. I need to develop a login validator module and expose it as a service. I want it to be service independent, i.e I should have the option of exposing it as a SOAP service or REST service in the future. What pattern should I follow ? Sorry if I am unclear in my requirements, I can clarify as per need. Thanks !! Edit : I am using Eclipse as an IDE and Jersey libraries. I am not into any framework, simply using the MVC pattern. I find a lot of difference between SOAP ann REST methods, so I want my methods to be implementation independent - i.e I should be easily able to use my method through a SOAP or REST service call as per need. What should I do for maximum flexibility ?

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  • Best practice for near reuse of model components?

    - by Chris Knight
    I have a requirement to use a Fund model in my code. It will contain a fund name and fund code. In the interest of reuse I've poked around the package containing the other models used and found an existing Fund model. However the issue here is that, in addition to fund name and code, it also contains an amount. Amount isn't directly relevant in my context. So, do I: 1) Use the existing Fund model as is, ignoring the setters/getters for fund amount. 2) Put a FundDescription interface onto the existing Fund model for accessing only the information I'm interested in. 3) Make a FundDescription base class from which the existing Fund model could now extend 4) Create a whole new seperate model since the two are slightly contextually different

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  • Command Query Separation validating for retries

    - by Neil Barnwell
    So I'm comfortable with the basic concept of CQS, where you might have a command that writes to one database, and that updates the query database that you read from. However, consider the scenario where you are entering data, and want to prevent duplicates. Using new employee data entry an employee register as an example, working through a pile of application forms to key in the new employees' details: Take top sheet. Key in employee name and unique payroll number to UI. Submit. Put paper in "completed pile". Repeat. How would you now prevent the user from keying in the same payroll number again, say for instance if they get distracted and can't remember whether they've keyed one in already and the "message" hasn't got all the way back to the query db for the user to search?

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  • PHP Access property of a class from within a class instantiated in the original class.

    - by Iain
    I'm not certain how to explain this with the correct terms so maybe an example is the best method... $master = new MasterClass(); $master->doStuff(); class MasterClass { var $a; var $b; var $c; var $eventProccer; function MasterClass() { $this->a = 1; $this->eventProccer = new EventProcess(); } function printCurrent() { echo '<br>'.$this->a.'<br>'; } function doStuff() { $this->printCurrent(); $this->eventProccer->DoSomething(); $this->printCurrent(); } } class EventProcess { function EventProcess() {} function DoSomething() { // trying to access and change the parent class' a,b,c properties } } My problem is i'm not certain how to access the properties of the MasterClass from within the EventProcess-DoSomething() method? I would need to access, perform operations on and update the properties. The a,b,c properties will be quite large arrays and the DoSomething() method would be called many times during the execuction of the script. Any help or pointers would be much appreciated :)

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  • How to handle too many files in Qt

    - by mree
    I'm not sure how to ask this, but here goes the question: I'm migrating from J2SE to Qt. After creating some small applications in Qt, I noticed that I've created way too many files compared to what I would've create if I was developing in Java (I use Netbeans). For an example, for a GUI to Orders, I'd have to create Main Order Search Window Edit Order Dialog Manage Order Dialog Maybe some other dialogs... For Java, I don't have to create a new file for every new Dialog, the Dialog will be created in the JFrame class itself. So, I will only be seeing 1 file for Orders which has other Dialogs in it. However, in Qt, I'd have to create 1 ui file, 1 header file, 1 cpp file for each of the Dialog (I know I can just put the cpp in the header, but it's easier to view codes in seperate files). So, in the end, I might end up with 3 (if there are 3 dialogs) x3 files = 9 files for the GUI in Qt, compared to Java which is only 1 file. I do know that I can create a GUI by coding it manually. But it seems easy on small GUIs but not some on complicated GUIs with lots of inputs, tabs and etc. So, is there any suggestion on how to minimize the file created in Qt?

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  • best-practice on for loop's condition

    - by guest
    what is considered best-practice in this case? for (i=0; i<array.length(); ++i) or for (i=array.length(); i>0; --i) assuming i don't want to iterate from a certain direction, but rather over the bare length of the array. also, i don't plan to alter the array's size in the loop body. so, will the array.length() become constant during compilation? if not, then the second approach should be the one to go for..

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  • Could this be considered a well-written PHP5 class?

    - by Ben Dauphinee
    I have been learning OOP principals on my own for a while, and taken a few cracks at writing classes. What I really need to know now is if I am actually using what I have learned correctly, or if I could improve as far as OOP is concerned. I have chopped a massive portion of code out of a class that I have been working on for a while now, and pasted it here. To all you skilled and knowledgeable programmers here I ask: Am I doing it wrong? class acl extends genericAPI{ // -- Copied from genericAPI class protected final function sanityCheck($what, $check, $vars){ switch($check){ case 'set': if(isset($vars[$what])){return(1);}else{return(0);} break; } } // --------------------------------- protected $db = null; protected $dataQuery = null; public function __construct(Zend_Db_Adapter_Abstract $db, $config = array()){ $this->db = $db; if(!empty($config)){$this->config = $config;} } protected function _buildQuery($selectType = null, $vars = array()){ // Removed switches for simplicity sake $this->dataQuery = $this->db->select( )->from( $this->config['table_users'], array('tf' => '(CASE WHEN count(*) > 0 THEN 1 ELSE 0 END)') )->where( $this->config['uidcol'] . ' = ?', $vars['uid'] ); } protected function _sanityRun_acl($sanitycheck, &$vars){ switch($sanitycheck){ case 'uid_set': if(!$this->sanityCheck('uid', 'set', $vars)){ throw new Exception(ERR_ACL_NOUID); } $vars['uid'] = settype($vars['uid'], 'integer'); break; } } private function user($action = null, $vars = array()){ switch($action){ case 'exists': $this->_sanityRun_acl('uid_set', $vars); $this->_buildQuery('user_exists_idcheck', $vars); return($this->db->fetchOne($this->dataQuery->__toString())); break; } } public function user_exists($uid){ return($this->user('exists', array('uid' => $uid))); } } $return = $acl_test->user_exists(1);

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  • How to track IIS server performance

    - by Chris Brandsma
    I have a reoccurring issue where a customer calls up and complains that the web site is too slow. Specifically, if they are inactive for a short period of time, then go back to the site, there will be a minute-two minute delay before the user sees a response. (the standard browser is Firefox in this case) I have Perfmon up and running, the cpu utilization is usually below 20% (single proc...don't ask). The database is humming along. And I'm pulling my hair out. So, what metrics/tools do you find useful when evaluating IIS performance?

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