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For a Javascript library, what is the best or standard way to support extensibility

- by Michael Best

Specifically, I want to support "plugins" that modify the behavior of parts of the library. I couldn't find much information on the web about this subject. But here are my ideas for how a library could be extensible. The library exports an object with both public and "protected" functions. A plugin can replace any of those functions, thus modifying the library's behavior. Advantages of this method are that it's simple and that the plugin's functions can have full access to the library's "protected" functions. Disadvantages are that the library may be harder to maintain with a larger set of exposed functions and it could be hard to debug if multiple plugins are involved (how to know which plugin modified which function?). The library provides an "add plugin" function that accepts an object with a specific interface. Internally, the library will use the plugin instead of it's own code if appropriate. With this method, the internals of the library can be rearranged more freely as long as it still supports the same plugin interface. This could also support having different plugin interfaces to modify different parts of the library. A disadvantage of this method is that the plugins may have to re-implement code that is already part of the library since the library's internal functions are not exported. The library provides a "set implementation" function that accepts an object inherited from a specific base object. The library's public API calls functions in the implementation object for any functionality that can be modified and the base implementation object includes the core functionality, with both external (to the API) and internal functions. A plugin creates a new implementation object, which inherits from the base object and replaces any functions it wants to modify. This combines advantages and disadvantages of both the other methods.

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Collision detection code style

- by Marian Ivanov

Not only there are two useful broad-phase algorithms and a lot of useful narrowphase algorithms, there are also multiple code styles. Arrays vs. calling Make an array of broadphase checks, then filter them with narrowphase checks, then resolve them. function resolveCollisions(thingyStructure * a,thingyStructure * b,int index){ possibleCollisions = getPossibleCollisions(b,a->get(index)); for(i=0; i<possibleCollitionsNumber; i++){ if(narrowphase(possibleCollisions[i],a[index])) { collisions->push(possibleCollisions[i]); }; }; for(i=0; i<collitionsNumber; i++){ //CODE FOR RESOLUTION }; }; Make the broadphase call the narrowphase, and the narrowphase call the resolution function resolveCollisions(thingyStructure * a,thingyStructure * b,int index){ broadphase(b,a->get(index)); }; function broadphase(thingy * with, thingy * what){ while(blah){ //blahcode narrowphase(what,collidingThing); }; }; Events vs. in-the-loop Fire an event. This abstracts the check away, but it's trickier to make an equal interaction. a[index] -> collisionEvent(eventdata); //much later int collisionEvent(eventdata){ //resolution gets here } Resolve the collision inside the loop. This glues narrowphase and resolution into one layer. if(narrowphase(possibleCollisions[i],a[index])) { //CODE GOES HERE }; The questions are: Which of the first two is better, and how am I supposed to make a zero-sum Newtonian interaction under B1.

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QapTcha error issue. Works locally, not on live server [migrated]

- by BlassFemur

I am adding QapTcha (http://demos.myjqueryplugins.com/qaptcha/) to a website that I am working on and I'm getting the error "Uncaught TypeError: Cannot read property 'error' of null". What's weird to me is everything is working perfectly locally. No errors or anything. Once I uploaded via ftp to the live server, I get the above error. Below is the block of code that seems to be generating the error: Slider.draggable({ revert: function(){ if(opts.autoRevert) { if(parseInt(Slider.css("left")) (bgSlider.width()-Slider.width()-10)) return false; else return true; } }, containment: bgSlider, axis:'x', stop: function(event,ui){ if(ui.position.left (bgSlider.width()-Slider.width()-10)) { // set the SESSION iQaptcha in PHP file $.post(opts.PHPfile,{ action : 'qaptcha', qaptcha_key : inputQapTcha.attr('name') }, function(data) { if(!data.error) Uncaught TypeError: Cannot read property 'error' of null { Slider.draggable('disable').css('cursor','default'); inputQapTcha.val(''); TxtStatus.text(opts.txtUnlock).addClass('dropSuccess').removeClass('dropError'); form.find('input[type=\'submit\']').removeAttr('disabled'); if(opts.autoSubmit) form.find('input[type=\'submit\']').trigger('click'); } },'json'); } } }); I'm not really sure what's going on as to why it works locally and not on the server. Any help/ suggestions would be appreciated. Thanks

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Does the HTMLEditor control raise any client-side events?

- by SAMIR BHOGAYTA

The HTML Editor has three modes: Design, HTML Text and preview mode. Design mode is in an IFrame. HTML Text is prensented in a TextArea and preview mode is in another Iframe. The code rendered about these three modes is as below. iframe id="editor1_ctl02_ctl00" name="editor1_ctl02_ctl00" marginheight="0" marginwidth="0" frameborder="0" src="javascript:false;" style="height:100%;width:100%;display:none;border-width:0px;" /iframe textarea id="editor1_ctl02_ctl01" class="ajax__htmleditor_htmlpanel_default" style="height:100%;width:100%;display:none;" /textarea iframe id="editor1_ctl02_ctl02" name="editor1_ctl02_ctl02" marginheight="0" marginwidth="0" frameborder="0" src="javascript:false;" style="height:100%;width:100%;display:none;border-width:0px;" /iframe In design mode, we can use the following JavaScript to append a callback function in onKeypress event. script type="text/javascript" var count = 0; function pageLoad() { $get('editor1_ctl02_ctl00').contentWindow.document.body.onkeypress = function() { count++; $get('cc').innerHTML = "you input " + count + "charactors"; }; } /script As a same way, you can append another keypress event on TextArea and preview IFrame.

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How would you TDD the functionality of getting the corresponding process of a running windows service?

- by Matt Spinelli

Purpose Over the last year or more I've been learning unit testing via books I've read recently like The Art of Unit Testing, Working Effectively with Legacy Code, and others. I've also been using unit tests, mocking frameworks, and the like, periodically at work and definitely see the value. However, I'm still having a hard time wrapping my mind around TDD (as opposed to TAD) when the situation calls for code that is gong to mostly use external API calls. Problem to solve Get the process associated with a windows service using the service name. example: Function GetProcess(ByVal serviceName As String) As Process Rules Show each major iteration in production & test code using TDD No need to see any other code or configuration that is required to get things to run. Just curious about the interfaces, concrete classes, and test methods. C# or VB.NET Must use the .Net framework regarding services/processes (i.e. System.Diagnostics.Process) Test Frameworks: Nunit or MSTest Isolation Frameworks: Moq, Rhino Mock, or Microsoft Moles Must write true unit tests (no integration tests) Additional notes As far as I can tell there are two approaches design wise. Use an Inversion of Control approach along with using the Adapter and/or Facade patterns to wrap the underlying .net framework objects dealing with processes and services. Keep the .net framework code in the class containing the Get Process method and use code detouring (interception) via Microsoft Moles to isolate the hard dependencies from the method under test.

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Take care to unhook Anonymous Delegates

- by David Vallens

Anonymous delegates are great, they elimiante the need for lots of small classes that just pass values around, however care needs to be taken when using them, as they are not automatically unhooked when the function you created them in returns. In fact after it returns there is no way to unhook them. Consider the following code. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Diagnostics; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { SimpleEventSource t = new SimpleEventSource(); t.FireEvent(); FunctionWithAnonymousDelegate(t); t.FireEvent(); } private static void FunctionWithAnonymousDelegate(SimpleEventSource t) { t.MyEvent += delegate(object sender, EventArgs args) { Debug.WriteLine("Anonymous delegate called"); }; t.FireEvent(); } } public class SimpleEventSource { public event EventHandler MyEvent; public void FireEvent() { if (MyEvent == null) { Debug.WriteLine("Attempting to fire event - but no ones listening"); } else { Debug.WriteLine("Firing event"); MyEvent(this, EventArgs.Empty); } } } } If you expected the anonymous delegates do die with the function that created it then you would expect the output Attempting to fire event - but no ones listeningFiring eventAnonymous delegate calledAttempting to fire event - but no ones listening However what you actually get is Attempting to fire event - but no ones listeningFiring eventAnonymous delegate calledFiring eventAnonymous delegate called In my example the issue is just slowing things down, but if your delegate modifies objects, then you could end up with dificult to diagnose bugs. A solution to this problem is to unhook the delegate within the function var myDelegate = delegate(){Console.WriteLine("I did it!");}; MyEvent += myDelegate; // .... later MyEvent -= myDelegate;

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Why doesn't the "scroll bar" on my laptop touchpad work?

- by Antonio Guzman Belmont

EDIT, from Google translate: Well buy my laptop with windows 7 and the touchpad has some arrows up and down to q deslises finger on the right side as if the q scroll the scroll bar handles, recently installed Ubuntu 11.10 and there is also served by the touchpad scroll so to speak but then asked me and I did update (late hours) and longer term attempt q dezlizar my finger down the right side of the touchpad and now low, anyone can tell me I can do about q to q and windows function as and ubuntu 11.10, I think now I have ubuntu 4.12 EDIT.2 (minimal tidy-up) I bought my laptop with Windows 7 installed. The touchpad has up/down arrows on the right side, as if this would scroll. When I installed Ubuntu 11.10, I was able to use this touchpad scroll function. I recently did an update (at some late hours) and i can no longer use right side of the touchpad to scroll. Can anyone tell me how to get the same function as I had in Windows and Ubuntu 11.10 ? I think I now have Ubuntu 12.04 Original question: Bueno compre mi lap con windows 7 y en el touchpad tiene unas flechitas arriba y abajo para q deslises el dedo del lado derecho como si fuese el scroll q maneja la barra de desplazamiento, recientemente instale ubuntu 11.10 y ahi servia tambien el scroll del touchpad por asi decirlo pero luego me pidio actualizar y lo hice(tardo horas) y ya q termino intento dezlizar mi dedo para bajar por la parte derecha del touchpad y ahora no baja, alguien me puede decir q puedo hacer al respecto para q funcione como e windows y en ubuntu 11.10, ahora tengo ubuntu 12.04 creo

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Dealing with curly brace soup

- by Cyborgx37

I've programmed in both C# and VB.NET for years, but primarily in VB. I'm making a career shift toward C# and, overall, I like C# better. One issue I'm having, though, is curly brace soup. In VB, each structure keyword has a matching close keyword, for example: Namespace ... Class ... Function ... For ... Using ... If ... ... End If If ... ... End If End Using Next End Function End Class End Namespace The same code written in C# ends up very hard to read: namespace ... { class ... { function ... { for ... { using ... { if ... { ... } if ... { ... } } } // wait... what level is this? } } } Being so used to VB, I'm wondering if there's a technique employed by c-style programmers to improve readability and to ensure that your code ends up in the correct "block". The above example is relatively easy to read, but sometimes at the end of a piece of code I'll have 8 or more levels of curly braces, requiring me to scroll up several pages to figure out which brace ends the block I'm interested in.

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Why is there no facility to overload static properties in PHP?

- by Jon

Intro PHP allows you to overload method calls and property accesses by declaring magic methods in classes. This enables code such as: class Foo { public function __get($name) { return 42; } } $foo = new Foo; echo $foo->missingProperty; // prints "42" Apart from overloading instance properties and methods, since PHP 5.3.0 we can also overload static methods calls by overriding the magic method __callStatic. Something missing What is conspicuously missing from the available functionality is the ability to overload static properties, for example: echo Foo::$missingProperty; // fatal error: access to undeclared static property This limitation is clearly documented: Property overloading only works in object context. These magic methods will not be triggered in static context. Therefore these methods should not be declared static. As of PHP 5.3.0, a warning is issued if one of the magic overloading methods is declared static. But why? My questions are: Is there a technical reason that this functionality is not currently supported? Or perhaps a (shudder) political reason? Have there been any aborted attempts to add this functionality in the past? Most importantly, the question is not "how can I have dynamic static properties in userland PHP?". That said, if you know of an especially cute implementation based on __callStatic that you want to share then by all means do so.

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What are the requirements to test a website using jquery.get() ? [migrated]

- by Frankie

I am working on a simple website. It has to search quite a few text files in different sub-folders. The rest of the page uses jquery, so I would like to use it for this also. The function I am looking at is .get() for downloading the files. So my main question is, can I test this on my local computer (Ubuntu Linux) or do I have to have it uploaded to a server? Also, if there's a better way to go about this, that would be nice to know. However, I'm more worried about getting it working. Thanks, Frankie PS: Heres the JS/jQuery code for downloading the files to an array. g_lists = new Array(); $(":checkbox").each(function(i){ if ($(this).attr("name") != "0") { var path = "../" + $(this).attr("name") + ".txt"; $("#bot").append("<br />" + path); // debug $.get(path, function(data){ g_lists[i] = data; $("#bot").html(data); }); } else { g_lists[i] = ""; } }); Edit: Just a note about the path variable. I think it's correct, but I'm not 100% sure. I'm new to web development. Here's some examples it produces and the directory tree of the site. Maybe it will help, can't hurt. . +-- include ¦ +-- jquery.js ¦ +-- load.js +-- index.xhtml +-- style.css +-- txt +-- Scripting_Tools +-- Editors.txt +-- Other.txt Examples of path: ../txt/Scripting_Tools/Editors.txt ../txt/Scripting_Tools/Other.txt Well I'm a new user, so I can't "answer" my own question, so I'll just post it here: After asking for help on a IRC chat channel specific to jQuery, I was told I could use this on a local host. To do this I installed Apache web server, and copied my site into it's directory. More information on setting it up can be found here: http://www.howtoforge.com/ubuntu_debian_lamp_server Then to run the site I navigated my browser to "localhost" and everything works.

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Go/Obj-C style interfaces with ability to extend compiled objects after initial release

- by Skrylar

I have a conceptual model for an object system which involves combining Go/Obj-C interfaces/protocols with being able to add virtual methods from any unit, not just the one which defines a class. The idea of this is to allow Ruby-ish open classes so you can take a minimalist approach to library development, and attach on small pieces of functionality as is actually needed by the whole program. Implementation of this involves a table of methods marked virtual in an RTTI table, which system functions are allowed to add to during module initialization. Upon typecasting an object to an interface, a Go-style lookup is done to create a vtable for that particular mapping and pass it off so you can have comparable performance to C/C++. In this case, methods may be added /afterwards/ which were not previously known and these new methods allow newer interfaces to be satisfied; while I like this idea because it seems like it would be very flexible (disregarding the potential for spaghetti code, which can happen with just about any model you use regardless). By wrapping the system calls for binding methods up in a set of clean C-compatible calls, one would also be able to integrate code with shared libraries and retain a decent amount of performance (Go does not do shared linking, and Objective-C does a dynamic lookup on each call.) Is there a valid use-case for this model that would make it worth the extra background plumbing? As much as this Dylan-style extensibility would be nice to have access to, I can't quite bring myself to a use case that would justify the overhead other than "it could make some kinds of code more extensible in future scenarios."

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Standard Network Tiers in a Distributed N-Tier System

Distributed N-Tier client/server architecture allows for segments of an application to be broken up and distributed across multiple locations on a network. Listed below are standard tiers in a Distributed N-Tier System. End-User Client Tier The End-User Client is responsible for sending and receiving requests from web servers and other applications servers and translating the responses so that the End-User can interpret the data effectively. The primary roles for this tier are to communicate with servers and translate server responses back to the end-user to interpret. Business-Specific Functions Validate Data Display Data Send Data to Webserver Web Server Tier The Web server tier processes new requests for information coming in from the HTTP and HTTPS ports. This primarily handles the generation of user interfaces and calls the application server when needed to access Data and business logic when needed. Business-specific functions Send Data to application server Format Data for Display Validate Data Application Server Tier The application server stores and executes predefined business logic that is applied to various pieces of data as the business determines. The processed data is then returned back to the Webserver. Additionally, this server directly calls the database to obtain and store any data used by the system Business-Specific Functions Validate Data Process Data Send Data to Database Server Database Server Tier The Database Server is responsible for storing and returning all data need by the calling applications. The primary role for this this server is storage. Data is stored as needed and can be recalled at any point later in time. Business-Specific Functions Insert Data Delete Data Return Data to Application Server

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Using PDO with MVC

- by mister martin

I asked this question at stackoverflow and received no response (closed as duplicate with no answer). I'm experimenting with OOP and I have the following basic MVC layout: class Model { // do database stuff } class View { public function load($filename, $data = array()) { if(!empty($data)) { extract($data); } require_once('views/header.php'); require_once("views/$filename"); require_once('views/footer.php'); } } class Controller { public $model; public $view; function __construct() { $this->model = new Model(); $this->view = new View(); // determine what page we're on $page = isset($_GET['view']) ? $_GET['view'] : 'home'; $this->display($page); } public function display($page) { switch($page) { case 'home': $this->view->load('home.php'); break; } } } These classes are brought together in my setup file: // start session session_start(); require_once('Model.php'); require_once('View.php'); require_once('Controller.php'); new Controller(); Now where do I place my database connection code and how do I pass the connection onto the model? try { $db = new PDO('mysql:host='.DB_HOST.';dbname='.DB_DATABASE.'', DB_USERNAME, DB_PASSWORD); $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch(PDOException $err) { die($err->getMessage()); } I've read about Dependency Injection, factories and miscellaneous other design patterns talking about keeping SQL out of the model, but it's all over my head using abstract examples. Can someone please just show me a straight-forward practical example?

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Validate that a Checkbox is checked using javascript

- by H(at)Ni

I was facing a challenge yesterday that I was creating a Visual webpart and I wanted to validate the a submit button is only visible if the user checked a "I agree to terms" checkbox. Something was weired that I tested my code on a normal asp.net website and it worked perfectly while it had a different behaviour inside the webpart which is whenever I check the checkbox, the button is enabled but it will not fire the asp.net validators in client side. It posts back the page and then the validators appear after that. So, I tried to change my type of thinking and I reached a different solution is that to call a javascript function whenever the button is clicked and then check if the checkbox is clicked or not. To illustrate more, here are an example to what I'm saying: 1. Button in aspx page: <asp:Button OnClientClick="CheckForCondition();" ValidationGroup="CompaniesSection" ID="btnCompaniesSubmit" runat="server" Text="Submit" /> 2. CheckForCondition() function: <script language="javascript" type="text/javascript"> function CheckForCondition() { if ($jq('#<%= ChkCompanyCheck.ClientID %>:checked').val() == undefined) { $jq('#lblCheckBox').show(); return false; } else { $jq('#lblCheckBox').hide(); return true; } } </script> 3. lblCheckBox is simply a label that shows a red asterisk beside the checkbox to indicate that it's a required field. <label id="lblCheckBox" style="color:Red;display:none">*</label>

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Javascript Canvas Drawing Efficiency

- by jujumbura

I have just recently started some experiments with game development in Javascript/HTML5, and so far it has been going pretty well. I have a simple test scene running with some basic input handling, and a hundred-ish drawImage() calls with a few transforms. This all runs great on Chrome, but unfortunately, it already chugs on Firefox. I am using a very large canvas ( 1920 x 1080 ), but it doesn't seem like I should be hitting my limit already. So on that note, I was hoping to ask a few questions: 1) What exactly is done on the CPU vs. the GPU in terms of canvas and drawImage()? I'm afraid the answer is probably "it depends on the browser", but can anybody give me some rules of thumb? I naively imagined that each drawImage call results in a textured quad on the GPU with the canvas effectively being a render target, but I'm wondering if I'm pretty far off base there... 2) I have seen posts here and there with people saying not to use the translate(), rotate(), scale() functions when drawing on the canvas. Am I adding a lot of overhead just by adding a translate() call, as opposed to passing in the x,y to drawImage()? Some people suggest using "transate3d", etc., which are CSS properties, but I'm not sure how to use them within a scene. Can they be used for animated sprites within a single canvas? 3) I have also seen a lot of posts with people mentioning that pre-building canvases and then re-using them is a lot faster than issuing all the individual draw calls again. I am guessing that my background should definitely be pre-built into a canvas, but how far should I take this? Should I maintain an individual canvas for each sprite, to cache all static image data when not animating? Thank you much for your advice!

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Automatically triggering standard spaceship controls to stop its motion

- by Garan

I have been working on a 2D top-down space strategy/shooting game. Right now it is only in the prototyping stage (I have gotten basic movement) but now I am trying to write a function that will stop the ship based on it's velocity. This is being written in Lua, using the Love2D engine. My code is as follows (note- object.dx is the x-velocity, object.dy is the y-velocity, object.acc is the acceleration, and object.r is the rotation in radians): function stopMoving(object, dt) local targetr = math.atan2(object.dy, object.dx) if targetr == object.r + math.pi then local currentspeed = math.sqrt(object.dx*object.dx+object.dy*object.dy) if currentspeed ~= 0 then object.dx = object.dx + object.acc*dt*math.cos(object.r) object.dy = object.dy + object.acc*dt*math.sin(object.r) end else if (targetr - object.r) >= math.pi then object.r = object.r - object.turnspeed*dt else object.r = object.r + object.turnspeed*dt end end end It is implemented in the update function as: if love.keyboard.isDown("backspace") then stopMoving(player, dt) end The problem is that when I am holding down backspace, it spins the player clockwise (though I am trying to have it go the direction that would be the most efficient at getting to the angle it would have to be) and then it never starts to accelerate the player in the direction opposite to it's velocity. What should I change in this code to get that to work? EDIT : I'm not trying to just stop the player in place, I'm trying to get it to use it's normal commands to neutralize it's existing velocity. I also changed math.atan to math.atan2, apparently it's better. I noticed no difference when running it, though.

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How to calculate square root in PHP [explained] [on hold]

- by Enes Imsirovic

At first code ! Don't forget embed the JQuery ! <html> <head> <title>Simple jQuery and PHP Square Root example</title> <script src="js/jquery-1.10.1.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function() { $('#form').submit(function(){ var number = $('#number').val(); $.ajax({type:"post",url:"calculate.php",data:"number=" +number,success:function(msg){$('#result').hide(); $("#result").html("<h3>" + msg + "</h3>").fadeIn("slow"); } }); return false; }); }); </script> </head> <body> <form id="form" action="calculate.php" method="post"> Enter number: <input id="number" type="text" name="number" /> <input id="submit" type="submit" value="Calculate Square Root" name="submit"/> </form> <p id="result"></p> </body> </html> Second code witch would be connected with first : calculate.php <?php if($_POST['number']==null){ echo "Please Enter a Number"; }else { if (!is_numeric($_POST['number'])) { echo "Please enter only numbers"; }else{ echo "Square Root of " .$_POST['number'] ." is ".sqrt($_POST['number']); } } ?> Chiefly for begginers, to see the power of PHP :) xD Load this on your localhost.. PHP files and JS : https://mega.co.nz/#!Et8zWSBb!KX2PFxa2Pzw_l-wi6QU8xi_eKTlHbtQuBsT_DvXrifk At least it look like this : http://imgur.com/vNnDRQ3

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How often is seq used in Haskell production code?

- by Giorgio

I have some experience writing small tools in Haskell and I find it very intuitive to use, especially for writing filters (using interact) that process their standard input and pipe it to standard output. Recently I tried to use one such filter on a file that was about 10 times larger than usual and I got a Stack space overflow error. After doing some reading (e.g. here and here) I have identified two guidelines to save stack space (experienced Haskellers, please correct me if I write something that is not correct): Avoid recursive function calls that are not tail-recursive (this is valid for all functional languages that support tail-call optimization). Introduce seq to force early evaluation of sub-expressions so that expressions do not grow to large before they are reduced (this is specific to Haskell, or at least to languages using lazy evaluation). After introducing five or six seq calls in my code my tool runs smoothly again (also on the larger data). However, I find the original code was a bit more readable. Since I am not an experienced Haskell programmer I wanted to ask if introducing seq in this way is a common practice, and how often one will normally see seq in Haskell production code. Or are there any techniques that allow to avoid using seq too often and still use little stack space?

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What is logical cohesion, and why is it bad or undesirable?

- by Matt Fenwick

From the c2wiki page on coupling & cohesion: Cohesion (interdependency within module) strength/level names : (from worse to better, high cohesion is good) Coincidental Cohesion : (Worst) Module elements are unrelated Logical Cohesion : Elements perform similar activities as selected from outside module, i.e. by a flag that selects operation to perform (see also CommandObject). i.e. body of function is one huge if-else/switch on operation flag Temporal Cohesion : operations related only by general time performed (i.e. initialization() or FatalErrorShutdown?()) Procedural Cohesion : Elements involved in different but sequential activities, each on different data (usually could be trivially split into multiple modules along linear sequence boundaries) Communicational Cohesion : unrelated operations except need same data or input Sequential Cohesion : operations on same data in significant order; output from one function is input to next (pipeline) Informational Cohesion: a module performs a number of actions, each with its own entry point, with independent code for each action, all performed on the same data structure. Essentially an implementation of an abstract data type. i.e. define structure of sales_region_table and its operators: init_table(), update_table(), print_table() Functional Cohesion : all elements contribute to a single, well-defined task, i.e. a function that performs exactly one operation get_engine_temperature(), add_sales_tax() (emphasis mine). I don't fully understand the definition of logical cohesion. My questions are: what is logical cohesion? Why does it get such a bad rap (2nd worst kind of cohesion)?

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Naming a class that processes orders

- by p.campbell

I'm in the midst of refactoring a project. I've recently read Clean Code, and want to heed some of the advice within, with particular interest in Single Responsibility Principle (SRP). Currently, there's a class called OrderProcessor in the context of a manufacturing product order system. This class is currently performs the following routine every n minutes: check database for newly submitted + unprocessed orders (via a Data Layer class already, phew!) gather all the details of the orders mark them as in-process iterate through each to: perform some integrity checking call a web service on a 3rd party system to place the order check status return value of the web service for success/fail email somebody if web service returns fail constantly log to a text file on each operation or possible fail point I've started by breaking out this class into new classes like: OrderService - poor name. This is the one that wakes up every n minutes OrderGatherer - calls the DL to get the order from the database OrderIterator (? seems too forced or poorly named) - OrderPlacer - calls web service to place the order EmailSender Logger I'm struggling to find good names for each class, and implementing SRP in a reasonable way. How could this class be separated into new class with discrete responsibilities?

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Database Driven Web Application, C# Front-End and F# Back-End meaning

- by user1473053

Hi I am an intern working with ASP.NET. My current task is to make a website which will incorporate some jquery viewing features. This project seems to me will be primarily dealing with reading data from a database and making graphs out of them. This will require me to make custom queries from whatever the client is looking at. I think it is going to be what this guy calls an Ad Hoc Query tool My plan for this is to make it a database-driven website. So I can utilize the jquery dynamic viewing capabilities. I stumbled upon the functional programming paradigm and found F#. I read that because of it's functional programming paradigm, it makes it a good language to do asynchronous functions. I read about how you can use this with LINQ to SQL and how easy it is to make queries without actually putting the query language in. I understand the concept of the MVC design pattern. But I don't understand what they mean about C# being the front-end and F# being the back-end. Can someone clarify this to me? Also what are your thoughts about doing this project in this way? Any comments and thoughts are greatly appreciated. I feel as if learning F# will be a great learning experience for me. My guess is that the F# back-end is like the part where it controls the calls to the database. F# is possibly the model part of the design pattern. And C# is the controller. So HTML, Javascript and Jquery stuff will be my View design pattern. Clarify please?

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Questions before I revamp my rendering engine to use shaders (GLSL)

- by stephelton

I've written a fairly robust rendering engine using OpenGL ES 1.1 (fixed-function.) I've been looking into revamping the engine to use OpenGL ES 2.0, which necessitates that I use shaders. I've been absorbing information all day long and still have some questions. Firstly, lighting. The fixed-function pipeline is guaranteed to have at least 8 lights available. My current engine finds lights that are "close" to the primitives being drawn and enables them; I don't know how many lights are going to be enabled until I draw a given model. Nothing is dynamically allocated in GLSL, so I have to define in a shader some number of lights to be used, right? So if I want to stick with 8, should I write my general purpose shader to have 8 lights and then use uniforms to tell it how many / which lights to use? Which brings me to another question: should I be concerned with the amount of data I'm allocating in a shader? Recent video cards have hundreds of "stream processors." If I've got a fragment shader being used on some number of fragments in a given triangle, I assume they must each have their own stack to work on. Are read-only variables copied here, or read when needed? My initial goal is to rework my code so that it is virtually identical to the current implementation. What I have in mind is to create my own matrix stack so that I can implement something along the lines of push/popMatrix and apply all my translations, rotations, and scales to this matrix, then provide the matrix to the vertex shader so that it can make very quick vertex translations. Is this approach sound? Edit: My original intention was to ask if there was a tutorial that would explain the bare minimum necessary to jump from fixed-function to using shaders. Thanks!

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Do objects maintain identity under all non-cloning conditions in PHP?

- by Buttle Butkus

PHP 5.5 I'm doing a bunch of passing around of objects with the assumption that they will all maintain their identities - that any changes made to their states from inside other objects' methods will continue to hold true afterwards. Am I assuming correctly? I will give my basic structure here. class builder { protected $foo_ids = array(); // set in construct protected $foo_collection; protected $bar_ids = array(); // set in construct protected $bar_collection; protected function initFoos() { $this->foo_collection = new FooCollection(); foreach($this->food_ids as $id) { $this->foo_collection->addFoo(new foo($id)); } } protected function initBars() { // same idea as initFoos } protected function wireFoosAndBars(fooCollection $foos, barCollection $bars) { // arguments are passed in using $this->foo_collection and $this->bar_collection foreach($foos as $foo_obj) { // (foo_collection implements IteratorAggregate) $bar_ids = $foo_obj->getAssociatedBarIds(); if(!empty($bar_ids) ) { $bar_collection = new barCollection(); // sub-collection to be a component of each foo foreach($bar_ids as $bar_id) { $bar_collection->addBar(new bar($bar_id)); } $foo_obj->addBarCollection($bar_collection); // now each foo_obj has a collection of bar objects, each of which is also in the main collection. Are they the same objects? } } } } What has me worried is that foreach supposedly works on a copy of its arrays. I want all the $foo and $bar objects to maintain their identities no matter which $collection object they become of a part of. Does that make sense?

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What are my choices for server side sandboxed scripting?

- by alfa64

I'm building a public website where users share data and scripts to run over some data. The scripts are run serverside in some sort of sandbox without other interaction this cycle: my Perl program reads from a database a User made script, adds the data to be processed into the script ( ie: a JSON document) then calls the interpreter, it returns the response( a JSON document or plain text), i save it to the database with my perl script. The script should be able to have some access to built in functions added to the scripting language by myself, but nothing more. So i've stumbled upon node.js as a javascript interpreter, and and hour or so ago with Google's V8(does v8 makes sense for this kind of thing?). CoffeeScript also came to my mind, since it looks nice and it's still Javascript. I think javascript is widespread enough and more "sandboxeable" since it doesn't have OS calls or anything remotely insecure ( i think ). by the way, i'm writing the system on Perl and Php for the front end. To improve the question: I'm choosing Javascript because i think is secure and simple enough to implement with node.js, but what other alternatives are for achieving this kind of task? Lua? Python? I just can't find information on how to run a sandboxed interpreter in a proper way.

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GLES2.0 3D Android game performance and multi threading the update?

- by Ofer

I have profiled my mixed Java\C++ Android game and I got the following result: https://dl.dropbox.com/u/8025882/PompiDev/AndroidProfile.png As you can see, the pink think is a C++ functions that updates the game. It does things like updating the logic but it mostly it generates a "request list" for rendering. The thing is, I generate DrawLists on C++ and then send them to Java to process and draw using GLES2.0. Since then I was able to improve update from 9ms down to about 7ms, but I would like to ask if I would benefit from multi threading the update? As I understand from that diagram is that the function that takes the most time is the one you see it's color on the timeline. So the pink area is taken mostly by update. The other area has MainOpenGL.Handle as it's main contributor(whch is my java function), but since it's not drawn to the top of the diagram I can conclude other things are happening at the same time that use the CPU? Or even GPU stuff that isn't shown in this diagram. I am not sure how the GPU works on this. Does it calculate stuff in parallel to the CPU? Or is it part of the CPU usage as in SoC? I am not sure. Anyway, in case GPU things DO happen in parallel to CPU, then I would guess that if I do this C++ Update in parallel to the thread that makes the OpenGL calls, I might make use of "dead CPU time" due to GPU stalling or maybe have the GPU calls getting processed earlier because it won't have to wait for Update to finish? How do you suggest to improve performance based on that? Thanks.

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