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• Creating a timesheet for work using PHP MySQL

  - by Justin

  I am trying to create a time-sheet for my work. I don't know if getting myself into a lot of work by doing this as I am quiet new to PHP and MYSQL but I do have a good understanding/knowledge of the two. I want the below fields in my database. Job weekPeriod ------A list of weeks Monday Sunday dateWorked ------List Of dates in the form coming from a database e.g. 1/1/2011 startTime ------List of times from 12:00am11:00pm 30 min intervals e.g. 11:30-12:30 endTime ------List of times from 12:00am11:00pm 30 min intervals e.g. 11:30-12:30 totalHours ------Automated amount ------Automated based on dayWorked comments ------Any messages here I want to be able to fill in some drop down boxes through a form that will then submit all information to my database. I want the script to know that if the date worked is on a Weekday Mon-Fri e.g. my rate of pay is 30.00ph On a sat it is 35.00ph and on a Sunday it is 40ph I then want to create a page where i select a particular week and see how many hours i worked and how much i earn and so on. Please let me know if there is such a program already established or if this is something that requires a bit of time and if I could do it being new to PHP and MYSQL

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• Program always returns binary '>>' : no operator found which takes a left-hand operand of type error

  - by Tom Ward

  So I've been set a task to create a temperature converter in C++ using this equation: Celsius = (5/9)*(Fahrenheit – 32) and so far I've come up with this (I've cut out the 10 lines worth of comments from the start so the code posted begins on line 11, if that makes any sense) #include <iostream> #include <string> #include <iomanip> #include <cmath> using namespace std; int main () { float celsius; float farenheit; std::cout << "**************************" << endl; std::cout << "*4001COMP-Lab5-Question 1*" << endl; std::cout << "**************************" << endl << endl; std::cout << "Please enter a temperature in farenheit: "; std::cin >> farenheit >> endl; std::cout << "Temperature (farenheit): " << endl; std::cout << "Temperature (celsius): " << celsius << endl; std::cin.get(); return 0; } Everytime I try to run this program I get a heap of errors with this one appearing every time: 1m:\visual studio 2010\projects\week 5\week 5\main.cpp(26): error C2678: binary '' : no operator found which takes a left-hand operand of type 'std::basic_istream<_Elem,_Traits' (or there is no acceptable conversion) I've tried everything I can think of to get rid of this error but it reappears every time, any idea on how to fix this?

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• How do I set a focus property on a TextInput that is built using AddChild?

  - by Huuuze

  I have the following MXML: <mx:State name="myState"> <mx:AddChild relativeTo="{myhbox}" position="after"> <mx:Box verticalAlign="middle" horizontalAlign="center" width="100%" height="100%"> <mx:Form id="myForm" width="479" verticalScrollPolicy="off" horizontalScrollPolicy="off"> <mx:FormItem label="My Label:" fontWeight="bold" id="myLabel" direction="vertical"> <mx:TextInput id="myTextInput" width="282" /> <mx:HBox> <mx:Button label="Go" click="go();" id="goButton" /> </mx:HBox> </mx:FormItem> </mx:Form> </mx:Box> </mx:AddChild> </mx:State> How do I set focus on the TextInput field using <mx:SetProperty/>? I've tried the following, but it only results in the field being highlighted -- the cursor does not appear in the TextInput: <mx:SetProperty target="{stage}" name="focus" value="{myTextInput}"/> Long story short, I want the cursor to appear in the field. UPDATE: I figured it out. See comments for solution.

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• Looping Through Database Query

  - by DrakeNET

  I am creating a very simple script. The purpose of the script is to pull a question from the database and display all answers associated with that particular question. We are dealing with two tables here and there is a foreign key from the question database to the answer database so answers are associated with questions. Hope that is enough explanation. Here is my code. I was wondering if this is the most efficient way to complete this or is there an easier way? <html> <head> <title>Advise Me</title> <head> <body> <h1>Today's Question</h1> <?php //Establish connection to database require_once('config.php'); require_once('open_connection.php'); //Pull the "active" question from the database $todays_question = mysql_query("SELECT name, question FROM approvedQuestions WHERE status = active") or die(mysql_error()); //Variable to hold $todays_question aQID $questionID = mysql_query("SELECT commentID FROM approvedQuestions WHERE status = active") or die(mysql_error()); //Print today's question echo $todays_question; //Print comments associated with today's question $sql = "SELECT commentID FROM approvedQuestions WHERE status = active"; $result_set = mysql_query($sql); $result_num = mysql_numrows($result_set); for ($a = 0; $a < $result_num; $a++) { echo $sql; } ?> </body> </html>

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• Need some ideas on how to acomplish this in Java (parsing strings)

  - by Matt

  Sorry I couldn't think of a better title, but thanks for reading! My ultimate goal is to read a .java file, parse it, and pull out every identifier. Then store them all in a list. Two preconditions are there are no comments in the file, and all identifiers are composed of letters only. Right now I can read the file, parse it by spaces, and store everything in a list. If anything in the list is a java reserved word, it is removed. Also, I remove any loose symbols that are not attached to anything (brackets and arithmetic symbols). Now I am left with a bunch of weird strings, but at least they have no spaces in them. I know I am going to have to re-parse everything with a . delimiter in order to pull out identifiers like System.out.print, but what about strings like this example: Logger.getLogger(MyHash.class.getName()).log(Level.SEVERE, After re-parsing by . I will be left with more crazy strings like: getLogger(MyHash getName()) log(Level SEVERE, How am I going to be able to pull out all the identifiers while leaving out all the trash? Just keep re-parsing by every symbol that could exist in java code? That seems rather lame and time consuming. I am not even sure if it would work completely. So, can you suggest a better way of doing this?

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• Ruby on rails 2 level model

  - by jony17

  I need some help creating a very simple forum in a existing model. What I want in a Game page, have a mini forum, where is possible create some topics and some comments to this topics. In the beginning I'm only implement topics. This is the error I have: Mysql2::Error: Column 'user_id' cannot be null: INSERT INTO `topics` (`game_id`, `question`, `user_id`) VALUES (1, 'asd', NULL) This is my main model: game.rb class Game < ActiveRecord::Base attr_accessible :name validates :user_id, presence: true validates :name, presence: true, length: { maximum: 50 } belongs_to :user has_many :topics, dependent: :destroy end topic.rb class Topic < ActiveRecord::Base validates_presence_of :question validates_presence_of :game_id attr_accessible :question, :user_id validates :question, length: {maximum: 50}, allow_blank: false belongs_to :game belongs_to :user end topic_controller.rb def create @game = Game.find(params[:game_id]) @topic = @game.topics.create(params[:topic]) @topic.user_id = current_user.id respond_to do |format| if @topic.save format.html { redirect_to @game, notice: 'Topic was successfully created.' } else format.html { render action: "new" } end end end game/show.html.erb <h2>Topics</h2> <% @game.topics.each do |topic| %> <p> <b>Question:</b> <%= topic.question %> </p> <% end %> <h2>Add a topic:</h2> <%= form_for([@game, @game.topics.build]) do |f| %> <div class="field"> <%= f.label :question %><br /> <%= f.text_field :question %> </div> <div class="actions"> <%= f.submit %> </div> <% end %> Thanks ;)

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• Javascript OOP - accessing the inherited property or function from a closure within a subclass

  - by Ali

  Hi All, I am using the javascript inheritance helper provided here: http://ejohn.org/blog/simple-javascript-inheritance/ I have the following code, and I have problem accessing the inherited property or function from a closure within a subclass as illustrated below. I am new to OOP javascript code and I appreciate your advice. I suppose within the closure, the context changes to JQuery (this variable) hence the problem. I appreciate your comments. Thanks, -A PS - Using JQuery 1.5 var Users = Class.extend({ init: function(names){this.names = names;} }); var HomeUsers = Users.extend({ work:function(){ // alert(this.names.length); // PRINTS A // var names = this.names; // If I make a local alias it works $.map([1,2,3],function(){ var newName = this.names.length; //error this.names is not defined. alert(newName); }); } }); var users = new HomeUsers(["A"]); users.work();

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• g++ fails mysteriously only if a .h is in a certain directory

  - by ggambett

  I'm experiencing an extremely weird problem in a fresh OSX 10.4.11 + Xcode 2.5 installation. I've reduced it to a minimal test case. Here's test.cpp: #include "macros.h" int main (void) { return 1; } And here's macros.h: #ifndef __JUST_TESTING__ #define __JUST_TESTING__ template<typename T> void swap (T& pT1, T& pT2) { T pTmp = pT1; pT1 = pT2; pT2 = pTmp; } #endif //__JUST_TESTING__ This compiles and works just fine if both files are in the same directory. HOWEVER, if I put macros.h in /usr/include/gfc2 (it's part of a custom library I use) and change the #include in test.cpp, compilation fails with this error : /usr/include/gfc2/macros.h:4: error: template with C linkage I researched that error and most of the comments point to a "dangling extern C", which doesn't seem to be the case at all. I'm at a complete loss here. Is g++ for some reason assuming everything in /usr/include/gfc2 is C even though it's included from a .cpp file that doesn't say extern "C" anywhere? Any ideas? EDIT : It does compile if I use the full path in the #include, ie #include "/usr/include/gfc2/macros.h" EDIT2 : It's not including the wrong header. I've verified this using cpp, g++ -E, and renaming macros.h to foobarmacros.h

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• C# WTF? Can anyone explain the strange behaviour?

  - by partizan

  Hi, guys. Here is the example with comments: class Program { // first version of structure public struct D1 { public double d; public int f; } // during some changes in code then we got D2 from D1 // Field f type became double while it was int before public struct D2 { public double d; public double f; } static void Main(string[] args) { // Scenario with the first version D1 a = new D1(); D1 b = new D1(); a.f = b.f = 1; a.d = 0.0; b.d = -0.0; bool r1 = a.Equals(b); // gives true, all is ok // The same scenario with the new one D2 c = new D2(); D2 d = new D2(); c.f = d.f = 1; c.d = 0.0; d.d = -0.0; bool r2 = c.Equals(d); // false, oops! this is not the result i've expected for } } So, what do you think about this?

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• paginate the class

  - by small

  please help me with pagination of this method my method is this one controller # def show @topic = Topic.find(params[:id]) @posts = @topic.posts.find(:all ,:order=> 'id') end views # %div{:style=>"margin: 0 auto;"} %table.sortable.style2{:cellpadding=>5} %thead %tr %td{:width => "25%",:align => "center",:style => "font-weight: bold;"}Posted By %td{:width => "75%",:style => "font-weight: bold;"}Comments %tbody - for post in @posts %tr %td{:align => "center"} &nbsp %div{:width=>"5px" , :style=>"border: 1px solid rgb(232, 232, 232);background-color: rgb(248, 248, 248);width: 60px; height:60px;" } - if post.posted_by.image = image_tag(post.posted_by.image.public_filename(),:width => "60px", :height => "60px",:align=>"center") %div{:style => "font-weight: bold; font-style: italic;"} = post.posted_by ? post.posted_by.firstname : "<em>Unknown User</em>" %br %div{:style => "font-style: italic;"} Posted on = post.created_at.strftime('%d of %B %Y ') = post.created_at.strftime('at %H:%M') %td{:valign => "top"} =post.body

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• how to make it easy for users to register at my site?

  - by rob

  I want to make it dirt simple for users coming to my site to register so they can post comments, vote on things, etc. I would like for them to be able to use their facebook id, twitter id, yahoo mail id, gmail id, AIM id, msn id, or whatever else people are likely to have (not necessarily all of those, but the more the better). I want my mom to be able to do it in 30 seconds or less. (that is, no "enter your open id url here" type thing that would confuse her). I prefer they not have to pick a unique name, as that gets annoying as the site gets more users and it gets hard to find one that is unique. What is the best option here? I'm not quite sure about OpenId vs. OAuth, and whether there are other options. And I'd like it to be as simple for me, the developer, as possible (of course!). I don't want to spend forever learning some protocol, nor have to structure my whole app around this. It would be great if there was a site with sample code that is pretty easy to drop in. BTW, StackOverflow is a good example of a site that was easy for me to register for.

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• What do I need to do besides code?

  - by user151841

  I'm a single-person operation for my small employer. I'm working on a couple of web applications that have grown to medium-size. We have backups going and everything is in version control with Subversion. I have comments in my code, but documentation outside of code is "spotty at best", and frequently things change. What do I need to do to bring it to the next level, beyond a pile of ( version-controlled, well-commented ) code? What would you say is required to have a robust set of documentation outside of the codebase itself, where the project is at, and where it's going? Ideally I would like some integrated system that would go from brainstorm, to requirements, to tracking bugs and features in svn check-in messages, to documentation. Would trac or redmine do something like this? I would like to show to my boss, "This is the prioritized list of features, this is where we are now, this is how long I spend on this feature, how long I spent on this bug" and I'd like to spend the minimum amount of time managing the projects :) What about ERD and UML diagrams? Is a project incomplete without them?

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• Using jQuery with form to eliminate spam

  - by Thierry-Dimitri Roy

  I have put a form on a web page where the user can send us data. Unfortunately, the webmaster does get a lot of spam through this form and the valid submissions gets buried. I have used captcha to bypass this problem. But I think that everyone would agree that captcha is a big annoyance to users. I switched to another solution: now the URL of the submit form points to null: <form id="sendDataForm" action="/null" method="post"> ... </form> And I bypass the form submission using jQuery excellent form plugin: $('#sendDataForm').ajaxForm({ url: '/ajax-data/' }); Since then, no spam has reached the webmaster, and valid comments gets through. The only drawbacks is that users without javascript cannot send us the form. But since this is on top of a javascript web application, we can safely assume that these are not valid users. My question is: in a world where 99% of users has javascript enabled (and a mechanism for those user could be build that uses captcha), why is this solution not more used? What drawback am I not seeing?

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• calculating change (over a period) for a dated field

  - by morpheous

  I have two tables with the following schema: CREATE TABLE sales_data ( sales_time date NOT NULL, product_id integer NOT NULL, sales_amt double NOT NULL ); CREATE TABLE date_dimension ( id integer NOT NULL, datestamp date NOT NULL, day_part integer NOT NULL, week_part integer NOT NULL, month_part integer NOT NULL, qtr_part integer NOT NULL, year_part integer NOT NULL, ); I want to write two types of queries that will allow me to calculate: period on period change (e.g. week on week change) change in period on period change (e.g. change in week on week change) I would prefer to write this in ANSI SQL, since I dont want to be tied to any particular db. [Edit] In light of some of the comments, if I have to be tied to a single database (in terms of SQL dialect), it will have to be PostgreSQL The queries I want to write are of the form (pseudo SQL of course): Query Type 1 (Period on Period Change) ======================================= a). select product_id, ((sd2.sales_amt - sd1.sales_amt)/sd1.sales_amt) as week_on_week_change from sales_data sd1, sales_data sd2, date_dimension dd where {SOME CRITERIA) b). select product_id, ((sd2.sales_amt - sd1.sales_amt)/sd1.sales_amt) as month_on_month_change from sales_data sd1, sales_data sd2, date_dimension dd where {SOME CRITERIA) Query Type 2 (Change in Period on Period Change) ================================================= a). select product_id, ((a2.week_on_week_change - a1.week_on_week_change)/a1.week_on_week_change) as change_on_week_on_week_change from (select product_id, ((sd2.sales_amt - sd1.sales_amt)/sd1.sales_amt) as week_on_week_change from sales_data sd1, sales_data sd2, date_dimension dd where {SOME CRITERIA) as a1), (select product_id, ((sd2.sales_amt - sd1.sales_amt)/sd1.sales_amt) as week_on_week_change from sales_data sd1, sales_data sd2, date_dimension dd where {SOME CRITERIA) as a2) WHERE {SOME OTHER CRITERIA}

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• Free cross-platform library to convert numbers (money amounts) to words?

  - by bialix

  I'm looking for cross-platform library which I can use in my C application to convert money amounts (e.g. $123.50) to words (one hundred twenty three dollars and fifty cents). I need support for multiple currencies: dollars, euros, UK pounds etc. Although I understand this is not hard at all to write my own implementation, but I'd like to avoid reinventing wheel. I've tried to google it, but there is too much noise related to MS Word converters. Can anybody suggest something? UPDATE numerous comments suggest to write my own implementation because it's really easy task. And I agree. My point was about support of multiple currencies in the same time and different business rules to spell the amounts (should be fractional part written as text or numbers? etc.) As I understand serious business applications have such library inside, but I think there is nothing open-source available, maybe because it seems as very easy task. I'm going to write my own libary and then open-source it. Thanks to all.

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• C++ bughunt - High-score insertion in a vector crashes the program

  - by Francisco P.

  Hello, everyone! I have a game I'm working on. My players are stored in a vector, and, at the end of the game, the game crashes when trying to insert the high-scores in the correct positions. Here's what I have (please ignore the portuguese comments, the code is pretty straightforward :P): //TOTAL_HIGHSCORES is the max. number of hiscores that i'm willing to store. This is set as 10. bool Game::updateHiScores() { bool stopIterating; bool scoresChanged = false; //Se ainda nao existirem TOTAL_HISCORES melhores pontuacoes ou se a pontuacao for melhor que uma das existentes for (size_t i = 0; i < players.size(); ++i) { //&& !(players[i].isAI()) if (players[i].getScoreValue() > 0 && (hiScores.size() < TOTAL_HISCORES || hiScores.back() < players[i].getScore())) { scoresChanged = true; if(hiScores.empty() || hiScores.back() >= players[i].getScore()) hiScores.push_back(players[i].getScore()); else { //Ciclo que encontra e insere a pontuacao no lugar desejado stopIterating = false; for(vector<Score>::iterator it = hiScores.begin(); it < hiScores.end() && !(stopIterating); ++it) { if(*it <= players[i].getScore()) { //E inserida na posicao 'it' o Score correspondente hiScores.insert(it, players[i].getScore()); //Verifica se o comprimento do vector esta dentro do desejado, se nao estiver, este e rectificado if (hiScores.size() > TOTAL_HISCORES) hiScores.pop_back(); stopIterating = true; } } } } } if (scoresChanged) sort(hiScores.begin(), hiScores.end(), higher); return scoresChanged; } What am I doing wrong here? Thanks for your time, fellas.

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• Dependency injection in C++

  - by Yorgos Pagles

  This is also a question that I asked in a comment in one of Miško Hevery's google talks that was dealing with dependency injection but it got buried in the comments. I wonder how can the factory / builder step of wiring the dependencies together can work in C++. I.e. we have a class A that depends on B. The builder will allocate B in the heap, pass a pointer to B in A's constructor while also allocating in the heap and return a pointer to A. Who cleans up afterwards? Is it good to let the builder clean up after it's done? It seems to be the correct method since in the talk it says that the builder should setup objects that are expected to have the same lifetime or at least the dependencies have longer lifetime (I also have a question on that). What I mean in code: class builder { public: builder() : m_ClassA(NULL),m_ClassB(NULL) { } ~builder() { if (m_ClassB) { delete m_ClassB; } if (m_ClassA) { delete m_ClassA; } } ClassA *build() { m_ClassB = new class B; m_ClassA = new class A(m_ClassB); return m_ClassA; } }; Now if there is a dependency that is expected to last longer than the lifetime of the object we are injecting it into (say ClassC is that dependency) I understand that we should change the build method to something like: ClassA *builder::build(ClassC *classC) { m_ClassB = new class B; m_ClassA = new class A(m_ClassB, classC); return m_ClassA; } What is your preferred approach?

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• PHP: How to know if a user is currently downloading a file?

  - by metrobalderas

  I'm developing a quick rapidshare-like site where the user can download files. First, I created a quick test setting headers and using readfile() but then I found in the comments section there's a way to limit the speed of the download, which is great, here's the code: $local_file = 'file.zip'; $download_file = 'name.zip'; // set the download rate limit (=> 20,5 kb/s) $download_rate = 20.5; if(file_exists($local_file) && is_file($local_file)) { header('Cache-control: private'); header('Content-Type: application/octet-stream'); header('Content-Length: '.filesize($local_file)); header('Content-Disposition: filename='.$download_file); flush(); $file = fopen($local_file, "r"); while(!feof($file)) { // send the current file part to the browser print fread($file, round($download_rate * 1024)); // flush the content to the browser flush(); // sleep one second sleep(1); } fclose($file);} else { die('Error: The file '.$local_file.' does not exist!'); } But now my question is, how to limit the number of downloads at the same time? How can I check there's still a connection with some user's IP? Thanks.

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• PC to Macbook Pro Transition - Getting (re)started?

  - by Torus Linvald

  I'm in my second computer science course right now. I've enjoyed programming so far, but really have just scraped my way by. I've not done much programming outside of required class work. For similar reasons, I never really invested in downloading/learning software to help me program (IDE's, editors, compilers, etc). I know it sounds tedious, but my current setup is: notepad++ for coding; Filezilla to transfer .cpp & .h files to school's aludra/unix and compiling; unix tells me where my bugs are and I go back to notepad++ to debug; repeat until done. This isn't fun - and I know it could be easier. But I put it off knowing that I was soon going to switch to a Mac. And, tomorrow, I'm switching. So... How should I set up my Macbook for the best programming experience? What IDEs and editors and debuggers and so on should I download? How will Mac programming differ from PC? I'm open to all ideas and comments, even the most basic. (Background - I'm learning/programming in C++ right now. Next semester, my classes switch to Java. I'm also going to take a class in web development, with HTML/CSS/Javascript/PHP. My new laptop will be a late 2009 Macbook Pro with Leopard, or maybe Snow Leopard. Free would be preferrable for all programs.) Thank you all.

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• C++ universal data type

  - by Gokul

  I have a universal data type, which is passed by value, but does not maintain the type information. We store only pointers and basic data types(like int, float etc) inside this. Now for the first time, we need to store std::string inside this. So we decided to convert it into std::string* and store it. Then comes the problem of destruction. We don't like to copy the std::string every time. So i am thinking of an approach like this. Say the data type looks like this class Atom { public : enum flags { IS_STRING, IS_EMPTY, HAS_GOT_COPIED, MARKER }; private: void* m_value; std::bitset<MARKER> m_flags; public: ..... Atom( Atom& atm ) { atm.m_flags.set( HAS_GOT_COPIED ); ..... } ..... ~Atom() { if( m_flags.test(IS_STRING) && !m_flags.test(HAS_GOT_COPIED) ) { std::string* val = static_cast<std::string*>(m_value); delete val; } } }; Is this a good approach to find out whether there is no more reference to std::string*? Any comments.. Thanks, Gokul.

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• Doubt on pointer conversion

  - by Simone

  Suppose we have the following code: #include <iostream> struct A { virtual void f() { std::cout << "A::f()" << std::endl; } }; struct B: A { void f() { std::cout << "B::f()" << std::endl; } }; void to_A(void* voidp) { A* aptr = static_cast<A*>(voidp); aptr->f(); } void to_B(void* voidp) { B* bptr2 = static_cast<B*>(voidp); bptr2->f(); } int main() { B* bptr = new B; void* voidp = bptr; to_A(voidp); // prints B::f() to_B(voidp); // prints B::f() } is this code guaranteed to always work as in the code comments or is it UB? AFAIK it should be ok, but I'd like to be reassured.

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• jQuery and array of objects

  - by sepoto

  $(document).ready(function () { output = ""; $.ajax({ url: 'getevents.php', data: { ufirstname: 'ufirstname' }, type: 'post', success: function (output) { alert(output); var date = new Date(); var d = date.getDate(); var m = date.getMonth(); var y = date.getFullYear(); $('#calendar').fullCalendar({ header: { left: 'prev,next today', center: 'title', right: 'month,basicWeek,basicDay' }, editable: true, events: output }); } }); }); I have code like this and if I copy the text verbatim out of my alert box and replace events: output with events: [{ id: 1, title: 'Birthday', start: new Date(1355011200*1000), end: new Date(1355011200*1000), allDay: true, url: 'http://www.yahoo.com/'},{ id: 2, title: 'Birthday Hangover', start: new Date(1355097600*1000), end: new Date(1355097600*1000), allDay: false, url: 'http://www.yahoo.com'},{ id: 3, title: 'Sepotomus Maximus Christmas', start: new Date(1356393600*1000), end: new Date(1356393600*1000), allDay: false, url: 'http://www.yahoo.com/'},] Everything works just fine. What can I do to fix this problem? I though that using events: output would place the text in that location but it does not seem to be working. Thank you all kindly in advance for any comments or answers!

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• How to handle ids and polymorphic associations in views if compound keys are not supported?

  - by duncan

  I have a Movie plan table: movie_plans (id, description) Each plan has items, which describe a sequence of movies and the duration in minutes: movie_plan_items (id, movie_plan_id, movie_id, start_minutes, end_minutes) A specific instance of that plan happens in: movie_schedules (id, movie_plan_id, start_at) However the schedule items can be calculated from the movie_plan_items and the schedule start time by adding the minutes create view movie_schedule_items as select CONCAT(p.id, '-', s.id) as id, s.id as movie_schedule_id, p.id as movie_plan_item_id, p.movie_id, p.movie_plan_id, (s.start_at + INTERVAL p.start_minutes MINUTE) as start_at, (s.start_at + INTERVAL p.end_minutes MINUTE) as end_at from movie_plan_items p, movie_schedules s where s.movie_plan_id=p.movie_plan_id; I have a model over this view (readonly), it works ok, except that the id is right now a string. I now want to add a polymorphic property (like comments) to various of the previous tables. Therefore for movie_schedule_items I need a unique and persistent numeric id. I have the following dilemma: I could avoid the id and have movie_schedule_items just use the movie_plan_id and movie_schedule_id as a compound key, as it should. But Rails sucks in this regard. I could create an id using String#hash or a md5, thus making it slower or collision prone (and IIRC String#hash is no longer persistent across processes in Ruby 1.9) Any ideas on how to handle this situation?

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• Casting/dereferencing member variable pointer from void*, is this safe?

  - by Damien

  Hi all, I had a problem while hacking a bigger project so I made a simpel test case. If I'm not omitting something, my test code works fine, but maybe it works accidentally so I wanted to show it to you and ask if there are any pitfalls in this approach. I have an OutObj which has a member variable (pointer) InObj. InObj has a member function. I send the address of this member variable object (InObj) to a callback function as void*. The type of this object never changes so inside the callback I recast to its original type and call the aFunc member function in it. In this exampel it works as expected, but in the project I'm working on it doesn't. So I might be omitting something or maybe there is a pitfall here and this works accidentally. Any comments? Thanks a lot in advance. (The problem I have in my original code is that InObj.data is garbage). #include <stdio.h> class InObj { public: int data; InObj(int argData); void aFunc() { printf("Inside aFunc! data is: %d\n", data); }; }; InObj::InObj(int argData) { data = argData; } class OutObj { public: InObj* objPtr; OutObj(int data); ~OutObj(); }; OutObj::OutObj(int data) { objPtr = new InObj(data); } OutObj::~OutObj() { delete objPtr; } void callback(void* context) { ((InObj*)context)->aFunc(); } int main () { OutObj a(42); callback((void*)a.objPtr); }

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• Is False == 0 and True == 1 in Python an implementation detail or guaranteed by the language?

  - by EOL

  Is it guaranteed that False == 0 and True == 1, in Python? For instance, is it in any way guaranteed that the following code will always produce the same results, whatever the version of Python (existing and in the foreseeable future)? 0 == False # True 1 == True # True ['zero', 'one'][False] # is 'zero' Any reference to the official documentation would be much appreciated! Other comments would be appreciated too… :) Edit: As noted in many answers, bool inherits from int. The question can therefore be recast as: "Is this an implementation detail that might change in the future, or does the documentation officially say that programmers can rely on booleans inheriting from integers?". This question is relevant for writing robust code that won't fail because of implementation details! Edit 2: The original question is still open, I believe (even though I accepted what I thought was the closest answer): even though Python 3 officially recognizes booleans as integers, I have not yet seen any official integer values for False and True… It therefore looks to me like it is best to stay clear from the assumption that False==0 and True==1.

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