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  • I don't understand the definition of side effects

    - by Chris Okyen
    I don't understand the wikipedia article on Side Effects: In computer science, a function or expression is said to have a side effect if, in addition to returning a value, it also 1.) Modifies some state or 2.) Has an observable interaction with calling functions or the outside world. I know an example of the first thing that causes a function or expression to have side effects - modifying a state Function and Expression modifying a state : 1.) foo(int X) { return x = x % x; } a = a + 1; What does 2.) - Has an observable interaction with calling functions or the outside world," mean? - Please give an example. The article continues on to say, "For example, a function might modify a global or static variable, modify one of its arguments, raise an exception, write data to a display or file, read data, or call other side-effecting functions...." Are all these examples, examples of 1.) - Modifiying some state , or are they also part of 2.) - Has an observable interaction with calling functions or the outside world?

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  • Is creating a separate pool for each individual image created from a png appropriate?

    - by Panzercrisis
    I'm still possibly a little green about object-pooling, and I want to make sure something like this is a sound design pattern before really embarking upon it. Take the following code (which uses the Starling framework in ActionScript 3): [Embed(source = "/../assets/images/game/misc/red_door.png")] private const RED_DOOR:Class; private const RED_DOOR_TEXTURE:Texture = Texture.fromBitmap(new RED_DOOR()); private const m_vRedDoorPool:Vector.<Image> = new Vector.<Image>(50, true); . . . public function produceRedDoor():Image { // get a Red Door image } public function retireRedDoor(pImage:Image):void { // retire a Red Door Image } Except that there are four colors: red, green, blue, and yellow. So now we have a separate pool for each color, a separate produce function for each color, and a separate retire function for each color. Additionally there are several items in the game that follow this 4-color pattern, so for each of them, we have four pools, four produce functions, and four retire functions. There are more colors involved in the images themselves than just their predominant one, so trying to throw all the doors, for instance, in a single pool, and then changing their color properties around isn't going to work. Also the nonexistence of the static keyword is due to its slowness in AS3. Is this the right way to do things?

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  • the correct way to deal with gtk_events_pending and gtk_main_iteration

    - by abd alsalam
    I have program that send files and i want to make a progress bar for it, but that progress bar just updated after the transferring complete,so i putted a gtk_events_pending() and gtk_main_iteration() functions in the sending loop to go back to the gtk main loop to update the progress bar but also it seems to not work here is a EDIT: the send function is in a separated thread snippet from my code float Percent = 0.0 ; float Interval = 0.0 ; the sending function gint SendTheFile ( ) { char FileBlockBuffer[512]; bzero(FileBlockBuffer, 512); int FileBlockSize ; FILE * FilePointer ; int filesize = 0 ; FilePointer = fopen(LocalFileName , "r"); struct stat st; stat(LocalFileName, &st); filesize = st.st_size; Interval = (512 / (float)filesize) ; while((FileBlockSize = fread(FileBlockBuffer,sizeof(char),512,FilePointer))>0) { send(SocketDiscriptor , FileBlockBuffer , FileBlockSize,0); bzero(FileBlockBuffer, 512); Percent = Percent + Interval ; if (Percent > 1.0)Percent = 0.0; while(gtk_events_pending() ) { gtk_main_iteration(); } } update progress bar function gint UpdateProgressBar(gpointer data) { gtk_progress_bar_set_fraction(GTK_PROGRESS_BAR(data),Percent); } updating progress bar in the main function g_timeout_add(50,(GSourceFunc)UpdateProgressBar,SendFileProgressBar);

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  • Is creating a separate pool for each individual png image in the same class appropriate?

    - by Panzercrisis
    I'm still possibly a little green about object-pooling, and I want to make sure something like this is a sound design pattern before really embarking upon it. Take the following code (which uses the Starling framework in ActionScript 3): [Embed(source = "/../assets/images/game/misc/red_door.png")] private const RED_DOOR:Class; private const RED_DOOR_TEXTURE:Texture = Texture.fromBitmap(new RED_DOOR()); private const m_vRedDoorPool:Vector.<Image> = new Vector.<Image>(50, true); . . . public function produceRedDoor():Image { // get a Red Door image } public function retireRedDoor(pImage:Image):void { // retire a Red Door Image } Except that there are four colors: red, green, blue, and yellow. So now we have a separate pool for each color, a separate produce function for each color, and a separate retire function for each color. Additionally there are several items in the game that follow this 4-color pattern, so for each of them, we have four pools, four produce functions, and four retire functions. There are more colors involved in the images themselves than just their predominant one, so trying to throw all the doors, for instance, in a single pool, and then changing their color properties around isn't going to work. Also the nonexistence of the static keyword is due to its slowness in AS3. Is this the right way to do things?

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  • How to refactor when all your development is on branches?

    - by Mark
    At my company, all of our development (bug fixes and new features) is done on separate branches. When it's complete, we send it off to QA who tests it on that branch, and when they give us the green light, we merge it into our main branch. This could take anywhere between a day and a year. If we try to squeeze any refactoring in on a branch, we don't know how long it will be "out" for, so it can cause many conflicts when it's merged back in. For example, let's say I want to rename a function because the feature I'm working on is making heavy use of this function, and I found that it's name doesn't really fit its purpose (again, this is just an example). So I go around and find every usage of this function, and rename them all to its new name, and everything works perfectly, so I send it off to QA. Meanwhile, new development is happening, and my renamed function doesn't exist on any of the branches that are being forked off main. When my issue gets merged back in, they're all going to break. Is there any way of dealing with this? It's not like management will ever approve a refactor-only issue so it has to be squeezed in with other work. It can't be developed directly on main because all changes have to go through QA and no one wants to be the jerk that broke main so that he could do a little bit of non-essential refactoring.

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  • Why is math taught "backwards"? [closed]

    - by Yorirou
    A friend of mine showed me a pretty practical Java example. It was a riddle. I got excited and quickly solved the problem. After it, he showed me the mathematical explanation of my solution (he proved why is it good), and it was completely clear for me. This seems like natural approach for me: solve problems, and generalize. This is very familiar to me, I do it all the time when I am programming: I write a function. When I have to write a similar function, I generalize the problem, grab the generic parts, and refactor them to a function, and solve the original problems as a specialization of the general function. At the university (or at least where I study), things work backwards. The professors shows just the highest possible level of the solutions ("cryptic" mathematical formulas). My problem is that this is too abstract for me. There is no connection of my previous knowledge (== reality in my sense), so even if I can understand it, I can't really learn it properly. Others are learning these formulas word-by-word, and get good grades, since they can write exactly the same to the test, but this is not an option for me. I am a curious person, I can learn interesting things, but I can't learn just text. My brain is for storing toughts, not strings. There are proofs for the theories, but they are also really hard to understand because of this, and in most of the cases they are omitted. What is the reason for this? I don't understand why is it a good idea to show the really high level of abstraction and then leave the practical connections (or some important ideas / practical motivations) out?

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  • Parse text file on click - and then display

    - by John R
    I am thinking of a methodology for rapid retrieval of code snippets. I imagine an HTML table with a setup like this: one two ... ten one oneTwo() oneTen() two twoOne() twoTen() ... ten tenOne() tenTwo() When a user clicks a function in this HTML table, a snippet of code is shown in another div tag or perhaps a popup window (I'm open to different solutions). I want to maintain only one PHP file named utitlities.php that contains a class called 'util'. This file & class will hold all the functions referenced in the above table (it is also used on various projects and is functional code). A key idea is that I do not want to update the HTML documentation everytime I write/update a new function in utilities.php. I should be able to click a function in the table and have PHP open the utilities file, parse out the apropriate function and display it in an HTML window. Questions: 1) I will be coding this in PHP and JavaScript but am wondering if similar scripts are available (for all or part) so I don't reinvent the wheel. 2) Quick & easy Ajax suggestions appreciated too (probably will use jquery, but am rusty). 3) Methodology for parsing out the functions from the utilities.php file (I'm not to good with regex).

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  • Parse text file on click and display

    - by John R
    I am thinking of a methodology for rapid retrieval of code snippets. I imagine an HTML table with a setup like this: one two ... ten one oneTwo() oneTen() two twoOne() twoTen() ... ten tenOne() tenTwo() When a user clicks a function in this HTML table, a snippet of code is shown in another div tag or perhaps a popup window (I'm open to different solutions). I want to maintain only one PHP file named utitlities.php that contains a class called 'util'. This file & class will hold all the functions referenced in the above table (it is also used on various projects and is functional code). A key idea is that I do not want to update the HTML documentation everytime I write/update a new function in utilities.php. I should be able to click a function in the table and have PHP open the utilities file, parse out the apropriate function and display it in an HTML window. Questions: 1) I will be coding this in PHP and JavaScript but am wondering if similar scripts are available (for all or part) so I don't reinvent the wheel. 2) Quick & easy Ajax suggestions appreciated too (probably will use jquery, but am rusty). 3) Methodology for parsing out the functions from the utilities.php file (I'm not to good with regex).

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  • How to retrieve the value of querystring from url using Javascript

    - by ybbest
    The following is a Javascript function I found on the internet , I keep here just in case I need to use it again. function getParameterByName(name) { name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]"); var regexS = "[\\?&]" + name + "=([^&#]*)"; var regex = new RegExp(regexS); var results = regex.exec(window.location.search); if(results == null) return ""; else return decodeURIComponent(results[1].replace(/\+/g, " ")); } You can also add this method to jquery as below. $.getParameterByName = function (name) { name = name.replace( /[\[]/ , "\\\[").replace( /[\]]/ , "\\\]"); var regexS = "[\\?&]" + name + "=([^&#]*)"; var regex = new RegExp(regexS); var results = regex.exec(window.location.search); if (results == null) return ""; else return decodeURIComponent(results[1].replace( /\+/g , " ")); }; $(document).ready(function () { alert($.getParameterByName("id")); }); References: http://stackoverflow.com/questions/901115/get-query-string-values-in-javascript http://blog.jeremymartin.name/2008/02/building-your-first-jquery-plugin-that.html http://stackoverflow.com/questions/7541218/writing-jquery-static-util-methods http://api.jquery.com/category/utilities/

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  • How to do MVC the right way

    - by Ieyasu Sawada
    I've been doing MVC for a few months now using the CodeIgniter framework in PHP but I still don't know if I'm really doing things right. What I currently do is: Model - this is where I put database queries (select, insert, update, delete). Here's a sample from one of the models that I have: function register_user($user_login, $user_profile, $department, $role) { $department_id = $this->get_department_id($department); $role_id = $this->get_role_id($role); array_push($user_login, $department_id, $role_id); $this->db->query("INSERT INTO tbl_users SET username=?, hashed_password=?, salt=?, department_id=?, role_id=?", $user_login); $user_id = $this->db->insert_id(); array_push($user_profile, $user_id); $this->db->query(" INSERT INTO tbl_userprofile SET firstname=?, midname=?, lastname=?, user_id=? ", $user_profile); } Controller - talks to the model, calls up the methods in the model which queries the database, supplies the data which the views will display(success alerts, error alerts, data from database), inherits a parent controller which checks if user is logged in. Here's a sample: function create_user(){ $this->load->helper('encryption/Bcrypt'); $bcrypt = new Bcrypt(15); $user_data = array( 'username' => 'Username', 'firstname' => 'Firstname', 'middlename' => 'Middlename', 'lastname' => 'Lastname', 'password' => 'Password', 'department' => 'Department', 'role' => 'Role' ); foreach ($user_data as $key => $value) { $this->form_validation->set_rules($key, $value, 'required|trim'); } if ($this->form_validation->run() == FALSE) { $departments = $this->user_model->list_departments(); $it_roles = $this->user_model->list_roles(1); $tc_roles = $this->user_model->list_roles(2); $assessor_roles = $this->user_model->list_roles(3); $data['data'] = array('departments' => $departments, 'it_roles' => $it_roles, 'tc_roles' => $tc_roles, 'assessor_roles' => $assessor_roles); $data['content'] = 'admin/create_user'; parent::error_alert(); $this->load->view($this->_at, $data); } else { $username = $this->input->post('username'); $salt = $bcrypt->getSalt(); $hashed_password = $bcrypt->hash($this->input->post('password'), $salt); $fname = $this->input->post('firstname'); $mname = $this->input->post('middlename'); $lname = $this->input->post('lastname'); $department = $this->input->post('department'); $role = $this->input->post('role'); $user_login = array($username, $hashed_password, $salt); $user_profile = array($fname, $mname, $lname); $this->user_model->register_user($user_login, $user_profile, $department, $role); $data['content'] = 'admin/view_user'; parent::success_alert(4, 'User Sucessfully Registered!', 'You may now login using your account'); $data['data'] = array('username' => $username, 'fname' => $fname, 'mname' => $mname, 'lname' => $lname, 'department' => $department, 'role' => $role); $this->load->view($this->_at, $data); } } Views - this is where I put html, css, and JavaScript code (form validation code for the current form, looping through the data supplied by controller, a few if statements to hide and show things depending on the data supplied by the controller). <!--User registration form--> <form class="well min-form" method="post"> <div class="form-heading"> <h3>User Registration</h3> </div> <label for="username">Username</label> <input type="text" id="username" name="username" class="span3" autofocus> <label for="password">Password</label> <input type="password" id="password" name="password" class="span3"> <label for="firstname">First name</label> <input type="text" id="firstname" name="firstname" class="span3"> <label for="middlename">Middle name</label> <input type="text" id="middlename" name="middlename" class="span3"> <label for="lastname">Last name</label> <input type="text" id="lastname" name="lastname" class="span3"> <label for="department">Department</label> <input type="text" id="department" name="department" class="span3" list="list_departments"> <datalist id="list_departments"> <?php foreach ($data['departments'] as $row) { ?> <option data-id="<?php echo $row['department_id']; ?>" value="<?php echo $row['department']; ?>"><?php echo $row['department']; ?></option> <?php } ?> </datalist> <label for="role">Role</label> <input type="text" id="role" name="role" class="span3" list=""> <datalist id="list_it"> <?php foreach ($data['it_roles'] as $row) { ?> <option data-id="<?php echo $row['role_id']; ?>" value="<?php echo $row['role']; ?>"><?php echo $row['role']; ?></option> <?php } ?> </datalist> <datalist id="list_collection"> <?php foreach ($data['tc_roles'] as $row) { ?> <option data-id="<?php echo $row['role_id']; ?>" value="<?php echo $row['role']; ?>"><?php echo $row['role']; ?></option> <?php } ?> </datalist> <datalist id="list_assessor"> <?php foreach ($data['assessor_roles'] as $row) { ?> <option data-id="<?php echo $row['role_id']; ?>" value="<?php echo $row['role']; ?>"><?php echo $row['role']; ?></option> <?php } ?> </datalist> <p> <button type="submit" class="btn btn-success">Create User</button> </p> </form> <script> var departments = []; var roles = []; $('#list_departments option').each(function(i){ departments[i] = $(this).val(); }); $('#list_it option').each(function(i){ roles[roles.length + 1] = $(this).val(); }); $('#list_collection option').each(function(i){ roles[roles.length + 1] = $(this).val(); }); $('#list_assessor option').each(function(i){ roles[roles.length + 1] = $(this).val(); }); $('#department').blur(function(){ var department = $.trim($(this).val()); $('#role').attr('list', 'list_' + department); }); var password = new LiveValidation('password'); password.add(Validate.Presence); password.add(Validate.Length, {minimum: 10}); $('input[type=text]').each(function(i){ var field_id = $(this).attr('id'); var field = new LiveValidation(field_id); field.add(Validate.Presence); if(field_id == 'department'){ field.add(Validate.Inclusion, {within : departments}); } else if(field_id == 'role'){ field.add(Validate.Inclusion, {within : roles}) } }); </script> The codes above are actually code from the application that I'm currently working on. I'm working on it alone so I don't really have someone to review my code for me and point out the wrong things in it so I'm posting it here in hopes that someone could point out the wrong things that I've done in here. I'm also looking for some guidelines in writing MVC code like what are the things that should be and shouldn't be included in views, models and controllers. How else can I improve the current code that I have right now. I've written some really terrible code before(duplication of logic, etc.) that's why I want to improve my code so that I can easily maintain it in the future. Thanks!

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  • Problems when rendering code on Nvidia GPU

    - by 2am
    I am following OpenGL GLSL cookbook 4.0, I have rendered a tesselated quad, as you see in the screenshot below, and i am moving Y coordinate of every vertex using a time based sin function as given in the code in the book. This program, as you see on the text in the image, runs perfectly on built in Intel HD graphics of my processor, but i have Nvidia GT 555m graphics in my laptop, (which by the way has switchable graphics) when I run the program on the graphic card, the OpenGL shader compilation fails. It fails on following instruction.. pos.y = sin.waveAmp * sin(u); giving error Error C1105 : Cannot call a non-function I know this error is coming on the sin(u) function which you see in the instruction. I am not able to understand why? When i removed sin(u) from the code, the program ran fine on Nvidia card. Its running with sin(u) fine on Intel HD 3000 graphics. Also, if you notice the program is almost unusable with intel HD 3000 graphics, I am getting only 9FPS, which is not enough. Its too much load for intel HD 3000. So, sin(X) function is not defined in the OpenGL specification given by Nvidia drivers or something else??

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  • How to handle the different frame rate on different devices?

    - by Fenwick
    I am not quite sure how frame per second works on a web page. I have a Canvas game that involves in moving an image from point A to B, and measuring the time elapsed. The code can be as simple as: var timeStamp = Date.now(); function update(){ obj.y += obj.speed; text = "Time: "+ (Date.now() - timeStamp) + "ms"; } The function update() is called every frame. The problem is that the time elapsed is different from device to device. It is pretty short on my PC, but get longer on my iPad, and is much longer on my cell phone. I thought it is because the FPS is smaller on mobile devices, so instead of calling update() every frame, I call it every 1ms by using a setInterval. But this does not solve the problem. In my understanding, the function for setInterval is invoked based on the increment in system time, other than frame rate, so it should fix the problem. Am I missing anything here? If the setInterval function is called based on FPS, is there any way to get around with the FPS difference across devices? On a side note, I have sort of a "water simulator" on the same canvas. It involves in redrawing about 60 objects which can be 600x600 pixels for every frame, so it could be a frame rate killer. I am using Phaser.js but not really using much of its functionalities, if that helps.

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  • Making WatiN Wait for JQuery document.Ready() Functions to Complete

    - by Steve Wilkes
    WatiN's DomContainer.WaitForComplete() method pauses test execution until the DOM has finished loading, but if your page has functions registered with JQuery's ready() function, you'll probably want to wait for those to finish executing before testing it. Here's a WatiN extension method which pauses test execution until that happens. JQuery (as far as I can see) doesn't provide an event or other way of being notified of when it's finished running your ready() functions, so you have to get around it another way. Luckily, because ready() executes the functions it's given in the order they're registered, you can simply register another one to add a 'marker' div to the page, and tell WatiN to wait for that div to exist. Here's the code; I added the extension method to Browser rather than DomContainer (Browser derives from DomContainer) because it's the sort of thing you only execute once for each of the pages your test loads, so Browser seemed like a good place to put it. public static void WaitForJQueryDocumentReadyFunctionsToComplete(this Browser browser) { // Don't try this is JQuery isn't defined on the page: if (bool.Parse(browser.Eval("typeof $ == 'function'"))) { const string jqueryCompleteId = "jquery-document-ready-functions-complete"; // Register a ready() function which adds a marker div to the body: browser.Eval( @"$(document).ready(function() { " + "$('body').append('<div id=""" + jqueryCompleteId + @""" />'); " + "});"); // Wait for the marker div to exist or make the test fail: browser.Div(Find.ById(jqueryCompleteId)) .WaitUntilExistsOrFail(10, "JQuery document ready functions did not complete."); } } The code uses the Eval() method to send JavaScript to the browser to be executed; first to check that JQuery actually exists on the page, then to add the new ready() method. WaitUntilExistsOrFail() is another WatiN extension method I've written (I've ended up writing really quite a lot of them) which waits for the element on which it is invoked to exist, and uses Assert.Fail() to fail the test with the given message if it doesn't exist within the specified number of seconds. Here it is: public static void WaitUntilExistsOrFail(this Element element, int timeoutInSeconds, string failureMessage) { try { element.WaitUntilExists(timeoutInSeconds); } catch (WatinTimeoutException) { Assert.Fail(failureMessage); } }

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  • Calling a webservice via Javascript

    - by jeroenb
    If you want to consume a webservice, it's not allways necessary to do a postback. It's even not that hard! 1. Webservice You have to add the scriptservice attribute to the webservice. [System.Web.Script.Services.ScriptService]public class PersonsInCompany : System.Web.Services.WebService { Create a WebMethod [WebMethod] public Person GetPersonByFirstName(string name) { List<Person> personSelect = persons.Where(p => p.FirstName.ToLower().StartsWith(name.ToLower())).ToList(); if (personSelect.Count > 0) return personSelect.First(); else return null; } 2. webpage Add reference to your service to your scriptmanager <script type="text/javascript"> function GetPersonInCompany() { var val = document.getElementById("MainContent_TextBoxPersonName"); PersonsInCompany.GetPersonByFirstName(val.value, FinishCallback); } function FinishCallback(result) { document.getElementById("MainContent_LabelFirstName").innerHTML = result.FirstName; document.getElementById("MainContent_LabelName").innerHTML = result.Name; document.getElementById("MainContent_LabelAge").innerHTML = result.Age; document.getElementById("MainContent_LabelCompany").innerHTML = result.Company; } </script> Add some javascript, where you first call your webservice. Classname.Webmethod = PersonsInCompany.GetPersonByFirstName Add a callback to catch the result from the webservice. And use the result to update your page. <script type="text/javascript"> function GetPersonInCompany() { var val = document.getElementById("MainContent_TextBoxPersonName"); PersonsInCompany.GetPersonByFirstName(val.value, FinishCallback); } function FinishCallback(result) { document.getElementById("MainContent_LabelFirstName").innerHTML = result.FirstName; document.getElementById("MainContent_LabelName").innerHTML = result.Name; document.getElementById("MainContent_LabelAge").innerHTML = result.Age; document.getElementById("MainContent_LabelCompany").innerHTML = result.Company; } </script>   If you have any question, feel free to contact me! You can download the code here.

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  • I need help with a timer for a text based game, i need to include a mysql query to it, but not sure how.

    - by Hijumper
    i would like to add a mysql query somewhere in my timer code so that everytime it restarts then 1 item would be added to the database, i can get it to show how many items you have gotten since the timer has been running, but im not quite sure how to add it into a mysql database, any help would be appreciated :D heres my timer code thus far: <head> <script type="text/javascript"> var c=10; var mineCount = 0; var t; var timer_is_on=0; function timedCount() { document.getElementById('txt').value = c; c = c - 1; if (c <= -1) { mineCount++; var _message = "You have mined " + mineCount + " iron ore" + (((mineCount > 1) ? "s" : "") + "!"); document.getElementById('message').innerHTML = _message; startover(); } } function startover() { c = 10; clearTimeout(t); timer_is_on=0; doMining(); } function doMining() { if (!timer_is_on) { timer_is_on = true; t = setInterval(function () { timedCount(); }, 1000); } } </script> <SPAN STYLE="float:left"> <form> <input type="button" value="Mining" onClick="doMining()"> <input type="text" id="txt"> </form> </SPAN> <html> <center> <div id='message'></div>

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  • pointers to member functions in an event dispatcher

    - by derivative
    For the past few days I've been trying to come up with a robust event handling system for the game (using a component based entity system, C++, OpenGL) I've been toying with. class EventDispatcher { typedef void (*CallbackFunction)(Event* event); typedef std::unordered_map<TypeInfo, std::list<CallbackFunction>, hash_TypeInfo > TypeCallbacksMap; EventQueue* global_queue_; TypeCallbacksMap callbacks_; ... } global_queue_ is a pointer to a wrapper EventQueue of std::queue<Event*> where Event is a pure virtual class. For every type of event I want to handle, I create a new derived class of Event, e.g. SetPositionEvent. TypeInfo is a wrapper on type_info. When I initialize my data, I bind functions to events in an unordered_map using TypeInfo(typeid(Event)) as the key that corresponds to a std::list of function pointers. When an event is dispatched, I iterate over the list calling the functions on that event. Those functions then static_cast the event pointer to the actual event type, so the event dispatcher needs to know very little. The actual functions that are being bound are functions for my component managers. For instance, SetPositionEvent would be handled by void PositionManager::HandleSetPositionEvent(Event* event) { SetPositionEvent* s_p_event = static_cast<SetPositionEvent*>(event); ... } The problem I'm running into is that to store a pointer to this function, it has to be static (or so everything leads me to believe.) In a perfect world, I want to store pointers member functions of a component manager that is defined in a script or whatever. It looks like I can store the instance of the component manager as well, but the typedef for this function is no longer simple and I can't find an example of how to do it. Is there a way to store a pointer to a member function of a class (along with a class instance, or, I guess a pointer to a class instance)? Is there an easier way to address this problem?

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  • Most common parts of a SELECT SQL query?

    - by jnrbsn
    I'm writing a function that generates a SELECT SQL query. (I'm not looking for a tool that already does this.) My function currently takes the following arguments which correspond to different parts of the SELECT query (the base table name is already known): where order fields joins group limit All of these arguments will be optional so that the function generates something like this by default: SELECT * FROM `table_name` I want to order the arguments so that the most often used parts of a SELECT query are first. That way the average call to the function will use as few of the arguments as possible rather than passing a null value or something like that to skip an argument. For example, if someone wanted to use the 1st and 3rd arguments but not the rest, they might have to pass a null value as the 2nd argument in order to skip it. So, for general purpose use, how should I order the arguments? Edit: To be more precise, out of the query parts I listed above, what is the order from most used to least used? Also, I'm not looking for solutions that allow me to not have to specify the order. Edit #2: The "fields" argument will default to "*" (i.e all fields/columns).

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  • Is application-specific data required for good unit testing?

    - by stinkycheeseman
    I am writing unit tests for a fairly simple function that depends on a fairly complicated set of data. Essentially, the object I am manipulating represents a graph and this function determines whether to chart a line, bar, or pie chart based on the data that came back from the server. This is a simplified version, using jQuery: setDefaultChartType: function (graphObject) { var prop1 = graphObject.properties.key; var numCols = 0; $.each(graphObject.columns, function (colIndex, column) { numCols++; }); if ( numCols > 6 || ( prop1 > 1 && graphObject.data.length == 1) ) { graphObject.setChartType("line"); } else if ( numCols <=6 && prop1 == 1 ) { graphObject.setChartType("bar"); } else if ( numCols <=6 && prop1 > 1 ) { graphObject.setChartType("pie"); } } My question is, should I use mock data that is procured from the actual database? Or can I just fabricate data that fits the different cases? I'm afraid that fabricating data will not expose bugs arising from changes in the database, but on the other hand, it would require a lot more effort to keep the test data up-to-date that I'm not sure is necessary.

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  • Are super methods in JavaScript limited to functional inheritance, as per Crockford's book?

    - by kindohm
    In Douglas Crockford's "JavaScript: The Good Parts", he walks through three types of inheritance: classical, prototypal, and functional. In the part on functional inheritance he writes: "The functional pattern also gives us a way to deal with super methods." He then goes on to implement a method named "superior" on all Objects. However, in the way he uses the superior method, it just looks like he is copying the method on the super object for later use: // crockford's code: var coolcat = function(spec) { var that = cat(spec), super_get_name = that.superior('get_name'); that.get_name = function (n) { return 'like ' + super_get_name() + ' baby'; }; return that; }; The original get_name method is copied to super_get_name. I don't get what's so special about functional inheritance that makes this possible. Can't you do this with classical or prototypal inheritance? What's the difference between the code above and the code below: var CoolCat = function(name) { this.name = name; } CoolCat.prototype = new Cat(); CoolCat.prototype.super_get_name = CoolCat.prototype.get_name; CoolCat.prototype.get_name = function (n) { return 'like ' + this.super_get_name() + ' baby'; }; Doesn't this second example provide access to "super methods" too?

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  • Many user stories share the same technical tasks: what to do?

    - by d3prok
    A little introduction to my case: As part of a bigger product, my team is asked to realize a small IDE for a DSL. The user of this product will be able to make function calls in the code and we are also asked to provide some useful function libraries. The team, together with the PO, put on the wall a certain number of user stories regarding the various libraries for the IDE user. When estimating the first of those stories, the team decided that the function call mechanism would have been an engaging but not completely obvious task, so the estimate for that user story raised up from a simple 3 to a more dangerous 5. Coming to the problem: The team then moved to the user stories regarding the other libraries, actually 10 stories, and added those 2 points of "function call mechanism" thing to each of those user story. This immediately raised up the total points for the product of 20 points! Everyone in the team knows that each user story could be picked up by the PO for the next iteration at any time, so we shouldn't isolate that part in one user story, but those 20 points feel so awfully unrealistic! I've proposed a solution, but I'm absolutely not satisfied: We created a "Design story" and put those annoying 2 points over it. However when we came to realize and demonstrate it to our customers, we were unable to show something really valuable for them about that story! Here the problem is whether we should ignore the principle of having isolated user stories (without any dependency between them). What would you do, or even better what have you done, in situations like this? (a small foot-note: following a suggestion I've moved this question from stackoverflow)

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  • How are the conceptual pairs Abstract/Concrete, Generic/Specific, and Complex/Simple related to one another in software architecture?

    - by tjb1982
    (= 2 (+ 1 1)) take the above. The requirement of the '=' predicate is that its arguments be comparable. Any two structures are comparable in this case, and so the contract/requirement is pretty generic. The '+' predicate requires that its arguments be numbers. That's more specific. (socket domain type protocol) the arguments here are much more specific (even though the arguments are still just numbers and the function itself returns a file descriptor, which is itself an int), but the arguments are more abstract, and the implementation is built up from other functions whose abstractions are less abstract, which are themselves built from less and less abstract abstractions. To the point where the requirements are something like move from one location to another, observe whether the switch at that location is on or off, turn the switch on or off, or leave it the same, etc. But are functions also less and less complex the less abstract they are? And is there a relationship between the number and range of arguments of a function and the complexity of its implementation, as you go from more abstract to less abstract, and vice versa? (= 2 (+ 1 1) 2r10) the '=' predicate is more generic than the '+' predicate, and thus could be more complex in its implementation. The '+' predicate's contract is less generic, and so could be less complex in its implementation. Is this even a little correct? What about the 'socket' function? Each of those arguments is a number of some kind. What they represent, though, is something more elaborate. It also returns a number (just like the others do), which is also a representation of something conceptually much more elaborate than a number. To boil it down, I'm asking if there is a relationship between the following dimensions, and why: Abstract/Concrete Complex/Simple Generic/Specific And more specifically, do different configurations of these dimensions have a specific, measurable impact on the number and range of the arguments (i.e., the contract) of a function?

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  • Is the capability to overwrite functions in JavaScript strength or weakness?

    - by S.N
    I recently came across the following code (from liferay.js) when I was working with Liferay: .... if (!Liferay._ajaxOld) { Liferay._ajaxOld = jQuery.ajax; } if (Liferay._ajaxOld) { jQuery.ajax = function(options) { if (Liferay.Util) { options.url = Liferay.Util.getURLWithSessionId(options.url); } return Liferay._ajaxOld(options); }; } .... As you can see, the code above overwrites the function "jQuery.ajax" to modify "options.url". One may say this is a strength of the language since we can easily overwrite and customize existing functions. However, I would imagine this capability can easily lead to a problem. For instance, my code can overwrite the same function "jQuery.ajax" to modify "options.url" differently from the code above. As a result, any code that expect the behavior defined by "liferay.js" may no longer function as expected. I see this as a weakness of the language as it does not provide proper encapsulation. What are the consensus about this feature/capability of the language in the field?

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  • Selecting objects on a 2D map

    - by Dave
    I have a object selection function by checking the mouse click and getting the relevant object. How ever there is a rare situation where if one object is partially behind the other then both objects are in the given area so im wondering how I can make the game know which one was selected, as currently my method does not know. This is my function that works it out: function getobj(e){ mx = e.pageX - curleft; //mouse click x my = e.pageY - curtop; //mouse click y function searchSprites(sprites, x, y) { var matches = [], i = 0, data = null; for (i = 0; i < spritea.length; ++i) { data = spritea[i].data; if (x > data[0] && y > data[1] && x < data[2] && y < data[3]) { var imageData = ctx2.getImageData(x, y, 1, 1); if(imageData.data[3] !== 0){ return [spritea[i].id]; i = spritea.length; } } } } res = searchSprites(spritea, mx, my); bid = res[0]; if(bid === '1'){ alert('You selected the skyscraper in front!'); }else if(bid === '3'){ alert('You selected the skyscraper behind!'); } } Image of the map: It keeps telling me I clicked the skyscraper behind which is not necessarily what the user is trying to do. How can I improve the accuracy of this ?

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  • Interfaces: profit of using

    - by Zapadlo
    First of all, my ubiquitous language is PHP, and I'm thinking about learning Java. So let me split my question on two closely related parts. Here goes the first part. Say I have a domain-model class. It has some getters, setters, some query methods etc. And one day I want to have a possibility to compare them. So it looks like: class MyEntity extends AbstractEntity { public function getId() { // get id property } public function setId($id) { // set id property } // plenty of other methods that set or retrieve data public function compareTo(MyEntity $anotherEntity) { // some compare logic } } If it would have been Java, I should have implemented a Comparable interface. But why? Polymorphism? Readbility? Or something else? And if it was PHP -- should I create Comparable interface for myself? So here goes the second part. My colleague told me that it is a rule of thumb in Java to create an interface for every behavioral aspect of the class. For example, if I wanted to present this object as a string, I should state this behaviour by something like implements Stringable, where in case of PHP Stringable would look like: interface Stringable { public function __toString(); } Is that really a rule of thumb? What benefits are gained with this approach? And does it worth it in PHP? And in Java?

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  • Help with selecting objects on a map

    - by Dave
    I have a object selection function by checking the mouse click and getting the relevant object. How ever there is a rare situation where if one object is partially behind the other then both objects are in the given area so im wondering how i can make the game know which one was selected, as currently my method does not know. This is my function that works it out: function getobj(e){ mx = e.pageX - curleft; //mouse click x my = e.pageY - curtop; //mouse click y function searchSprites(sprites, x, y) { var matches = [], i = 0, data = null; for (i = 0; i < spritea.length; ++i) { data = spritea[i].data; if (x > data[0] && y > data[1] && x < data[2] && y < data[3]) { var imageData = ctx2.getImageData(x, y, 1, 1); if(imageData.data[3] !== 0){ return [spritea[i].id]; i = spritea.length; } } } } res = searchSprites(spritea, mx, my); bid = res[0]; if(bid === '1'){ alert('You selected the skyscraper in front!'); }else if(bid === '3'){ alert('You selected the skyscraper behind!'); } } Image of the map: http://i.imgur.com/qcKij.jpg It keeps telling me i clicked the skyscraper behind which is not necessarily what the user is trying to do... how can i improve the accuracy of this ?

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