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• Is ASP.NET MVC is really MVC? Or how to separate model from controller?

  - by Andrey

  Hi all, This question is a bit rhetorical. At some point i got a feeling that ASP.NET MVC is not that authentic implementation of MVC pattern. Or i didn't understood it. Consider following domain: electric bulb, switch and motion detector. They are connected together and when you enter the room motion detector switches on the bulb. If i want to represent them as MVC: switch is model, because it holds the state and contains logic bulb is view, because it presents the state of model to human motion detector is controller, because it converts user actions to generic model commands Switch has one private field (On/Off) as a State and two methods (PressOn, PressOff). If you call PressOn when it is Off it goes to On, if you call it again state doesn't change. Bulb can be replaced with buzzer, motion detector with timer or button, but the model still represent the same logic. Eventually system will have same behavior. This is how i understand classical MVC decomposition, please correct me if i am wrong. Now let's decompose it in ASP.Net MVC way. Bulb is still a view Controller will be switch + motion detector Model is some object that will just pass state to bulb. So the logic that defines behavior moves to controller. Question 1: Is my understanding of MVC and ASP.NET MVC correct? Question 2: If yes, do you agree that ASP.NET MVC is not 100% accurate implementation? And back to life. The final question is how to separate model from controller in case of ASP.NET MVC. There can be two extremes. Controller does basic stuff and call model to do all the logic. Another is controller does all the logic and model is just something like class with properties that is mapped to DB. Question 3: Where should i draw the line between this extremes? How to balance? Thanks, Andrey

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• Rails preventing duplicates in polymorphic has_many :through associations

  - by seaneshbaugh

  Is there an easy or at least elegant way to prevent duplicate entries in polymorphic has_many through associations? I've got two models, stories and links that can be tagged. I'm making a conscious decision to not use a plugin here. I want to actually understand everything that's going on and not be dependent on someone else's code that I don't fully grasp. To see what my question is getting at, if I run the following in the console (assuming the story and tag objects exist in the database already) s = Story.find_by_id(1) t = Tag.find_by_id(1) s.tags << t s.tags << t My taggings join table will have two entries added to it, each with the same exact data (tag_id = 1, taggable_id = 1, taggable_type = "Story"). That just doesn't seem very proper to me. So in an attempt to prevent this from happening I added the following to my Tagging model: before_validation :validate_uniqueness def validate_uniqueness taggings = Tagging.find(:all, :conditions => { :tag_id => self.tag_id, :taggable_id => self.taggable_id, :taggable_type => self.taggable_type }) if !taggings.empty? return false end return true end And it works almost as intended, but if I attempt to add a duplicate tag to a story or link I get an ActiveRecord::RecordInvalid: Validation failed exception. It seems that when you add an association to a list it calls the save! (rather than save sans !) method which raises exceptions if something goes wrong rather than just returning false. That isn't quite what I want to happen. I suppose I can surround any attempts to add new tags with a try/catch but that goes against the idea that you shouldn't expect your exceptions and this is something I fully expect to happen. Is there a better way of doing this that won't raise exceptions when all I want to do is just silently not save the object to the database because a duplicate exists?

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• Bind postback data from a strong type view of type List<T>

  - by Robert Koritnik

  I have a strong type view of type List<List<MyViewModelClass>> The outer list will always have two lists of List<MyViewModelClass>. For each of the two outer lists I want to display a group of checkboxes. Each set can have an arbitrary number of choices. My view model class looks similar to this: public class MyViewModelClass { public Area Area { get; set; } public bool IsGeneric { get; set; } public string Code { get; set; } public bool IsChecked { get; set; } } So the final view will look something like: Please select those that apply: First set of choices: x Option 1 x Option 2 x Option 3 etc. Second set of choices: x Second Option 1 x Second Option 2 x Second Option 3 x Second Option 4 etc. Checkboxes should display MyViewModelClass.Area.Name, and their value should be related to MyViewModelClass.Area.Id. Checked state is of course related to MyViewModel.IsChecked. Question I wonder how should I use Html.CheckBox() or Html.CheckBoxFor() helper to display my checkboxes? I have to get these values back to the server on a postback of course. I would like to have my controller action like one of these: public ActionResult ConsumeSelections(List<List<MyViewModelClass>> data) { // process data } public ActionResult ConsumeSelections(List<MyViewModelClass> first, List<MyViewModelClass> second) { // process data } If it makes things simpler, I could make a separate view model type like: public class Options { public List First { get; set; } public List Second { get; set; } } As well as changing my first version of controller action to: public ActionResult ConsumeSelections(Options data) { // process data }

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• How to fix this java.lang.LinkageError?

  - by Péter Török

  I am trying to configure a custom layout class to Log4J as described in my previous post. The class uses java.util.regex.Matcher to identify potential credit card numbers in log messages. It works perfectly in unit tests (I can also programmatically configure a logger to use it and produce the expected output). However when I try to deploy it with our app in JBoss, I get the following error: --- MBEANS THAT ARE THE ROOT CAUSE OF THE PROBLEM --- ObjectName: jboss.web.deployment:war=MyWebApp-2010_02-SNAPSHOT.war,id=476602902 State: FAILED Reason: java.lang.LinkageError: java/util/regex/Matcher I couldn't even find any info on this form of the error - typically LinkageError seems to show up with a "loader constrain violation" message, like in here. Technical details: we use JBoss 4.2, Java 5, Log4J 1.2.12. We deploy our app in an .ear, which contains (among others) the above mentioned .war file, and the custom layout class in a separate jar file. We override the default settings in jboss-log4J.xml with our own log4j.properties located in a different folder, which is added to the classpath at startup, and is provided via Carbon. I can only guess: are two different Matcher class versions loaded from somewhere, or is Matcher loaded by two different classloaders when it is used from the jar and the war? What does this error message mean, and how can I fix it?

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• django html/css windows mac problem width additional space on the top of the page

  - by rafal

  Hi, my problem is really strange... We are developing shopping-cart system in django. The problem is, when I change anything even single letter on my computer, strange space on the top of the page appears, see the picture... I don't know since when the problem appears. But if i go back to previous version (in this case 210, we use svn), everything is ok, until i change something. I'm using windows 7 and i tried to edit this file in notepad, notepad++, e and so on... In the case when my friend changes something in this 210 version on Macbook everything is ok. Have anyone any ideas? Also in source code of the page strange "-" is added before doctype, but it is only visible in chrome. But the problem is for all browsers...! what is more... for example my home page extends, categories.html and base.html, and in this case a have two "--". Of course If i change something in this two files base and home... PLEASE HELP!:) http://img402.imageshack.us/img402/5655/buguh.png [2]:

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• Do [sprite stopActionByTag: kTag]; working differently for different CCActions ?

  - by srikanth rongali

  //prog 1 -(void)gameLogic:(ccTime)dt { id actionMove = [CCMoveTo actionWithDuration:1.0 position:ccp(windowSize.width/2-400, actualY)]; [actionMove setTag:6]; [self schedule:@selector(update:)]; [hitBullet runAction:actionMove]; } -(void)update:(ccTime)dt { if ( (CGRectIntersectsRect(hitRect, playerRect)) ) { [[[self getActionByTag:6] retain] autorelease]; [hitBullet stopActionByTag: 6]; } } //prog 2 -(void)gameLogic:(ccTime)dt { id actionMove = [CCMoveTo actionWithDuration:1.0 position:ccp(windowSize.width/2-400, actualY)]; id hitBulletAction = [CCSequence actionWithDuration:(intervalforEnemyshoot)]; id hitBulletSeq = [CCSequence actions: hitBulletAction, actionMove, nil]; [hitBulletSeq setTag:5]; [self schedule:@selector(update:)]; [hitBullet runAction:hitBulletSeq]; } -(void)update:(ccTime)dt { if ( (CGRectIntersectsRect(hitRect, playerRect)) ) { [[[self getActionByTag:5] retain] autorelease]; [hitBullet stopActionByTag: 5]; } } While prog1 is working prog2 is not working ? I think the both are same. But why the two stopActions are working differently in two prog1 and prog2 ? I mean the actions are stopped in prog1 but the actions are not stopping in prog2 ? thank You.

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• Adding changes from one Mercurial repository to another

  - by Patrik Hägne

  When changing the VCS for my project FakeItEasy from SVN to Mercurial on Google Code I was a bit too eager (I'm funny like that). What I did was just checking the latest version out of SVN and then commiting that checkout as the first revision of the new Mercurial repo. This obviously has the effect that all history is lost. Later when getting a bit better acustomed to Mercurial I realized that there is such a thing as a "convert extension" that allows you to convert a SVN repo into a Mercurial repo. Now what I want to do is to convert the old SVN repo and then have all change sets from the currently existing Mercurial repo imported into this converted repo except the very first commit to Mercurial. I've converted the SVN repo to a local Mercurial repo but now is when I'm stuck. I thought I'd be able to use the convert extension to bring the current Mercurial repository into the converted one and having a splice map remove the first commit but I can not seem to get this to work. I've also tried to just use convert without splice map to get all change sets from the current Mercurial repo into the converted one and the rebase the second version in the current to the last commit from the old SVN repository but I can't get that to work either. To make this clearer lets say I have these two repositories: A: revA1-revA2 B: revB1-revB2-revB3 (Where revB1 is actually a copy of revA2) Now I want to combine these two into the new repository containing this: C: revA1-revA2-revB2-revB3

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• .NET out of memory troubleshooting

  - by bushman

  After reading a few enlightening articles about memory in the .NET technology, Out of Memory does not refer to physical memory, 597499. I thought I understood why a C# app would throw an out of memory exception -- until I started experimenting with two servers-- both are having 2.5 gigs of ram, windows server 2003 and identical programs running. The only significant difference between the two being one has 7% hard drive storage left and the other more than 50%. The server with 7% storage space left is consistently throwing an out of memory while the other is performing consistently well. My app is a C# web application that process' hundreds of MBs of String object. Why would this difference happen seeing that the most likely reason for the out of memory issue is out of contiguous virtual address space -- What solutions do you guys propose -- and what do you say about the following 1. turn on the 3gb switch to increase the virtual address space -- 2. instead of using one giant string object, break it up into smaller pieces and collect it in a jagged array (here I have to find a way to return to the caller in some other way as right now, the return type is a string) thanks SO

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• Add multiple entities to Javascript namespace from different files

  - by Brian M. Hunt

  Given a namespaces ns used in two different files: abc.js ns = ns || (function () { foo = function() { ... }; return { abc : foo }; }()); def.js // is this correct? ns = ns || {} ns.def = ns.def || (function () { defoo = function () { ... }; return { deFoo: defoo }; }()); Is this the proper way to add def to the ns to a namespace? In other words, how does one merge two contributions to a namespace in javascript? If abc.js comes before def.js I'd expect this to work. If def.js comes before abc.js I'd expect ns.abc to not exist because ns is defined at the time. It seems there ought to be a design pattern to eliminate any uncertainty of doing inclusions with the javascript namespace pattern. I'd appreciate thoughts and input on how best to go about this sort of 'inclusion'. Thanks for reading. Brian

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• Can Haskell's Parsec library be used to implement a recursive descent parser with backup?

  - by Thor Thurn

  I've been considering using Haskell's Parsec parsing library to parse a subset of Java as a recursive descent parser as an alternative to more traditional parser-generator solutions like Happy. Parsec seems very easy to use, and parse speed is definitely not a factor for me. I'm wondering, though, if it's possible to implement "backup" with Parsec, a technique which finds the correct production to use by trying each one in turn. For a simple example, consider the very start of the JLS Java grammar: Literal: IntegerLiteral FloatingPointLiteral I'd like a way to not have to figure out how I should order these two rules to get the parse to succeed. As it stands, a naive implementation like this: literal = do { x <- try (do { v <- integer; return (IntLiteral v)}) <|> (do { v <- float; return (FPLiteral v)}); return(Literal x) } Will not work... inputs like "15.2" will cause the integer parser to succeed first, and then the whole thing will choke on the "." symbol. In this case, of course, it's obvious that you can solve the problem by re-ordering the two productions. In the general case, though, finding things like this is going to be a nightmare, and it's very likely that I'll miss some cases. Ideally, I'd like a way to have Parsec figure out stuff like this for me. Is this possible, or am I simply trying to do too much with the library? The Parsec documentation claims that it can "parse context-sensitive, infinite look-ahead grammars", so it seems like something like I should be able to do something here.

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• Google Maps API - Get points along route between lat/long

  - by user311374

  I have a web site that I am trying to get completed and I need to have the user click points on a map and then work out the route on the roads between the two points. So the user clicks the first point on 1st street, and then clicks another point on 4th street, and the map will find the best way to get there and plot the route on the map. I am assuming this can be done using directions and parse it up, but I have been searching for an hour now and can't find what I am looking for (maybe bad search terms). I need to be able to plot the map manually (?) so I can calculate the distance, etc... of the route as the user continues to click. The site that is in beta is http://www.RunMyRoute.com/UserRoutes/Create and you can see I am trying to create running routes. I want the user to have the option for the route to follow the roads versus just a straight line between two points on the map. Any help on this would be great! Simon.

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• When do you tag your software project?

  - by WilhelmTell of Purple-Magenta

  I realize there are various kinds of software projects: commercial (for John Doe) industrial (for Mr. Montgomery Burns) successful open-source (with audience larger than, say, 10 people) personal projects (with audience size in the vicinity of 1). each of which release a new version of their product on difference conditions. I'm particularly interested in the case of personal projects and open-source projects. When, or under what conditions, do you make a new release of any kind? Do you subscribe to a fixed recurring deadline such as every two weeks? Do you commit to a release of at least 10 minor fixes, or one major fix? Do you combine the two conditions such as at least one condition must hold, or both must hold? I reckon this is a subjective question. I ask this question in light of searching for tricks to keep my projects alive and kicking. Sometimes my projects are active but look as if they aren't because I don't have the confidence to make a release or a tag of any sort for a long time -- in the order of months.

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• Number of ways to place kings on chess board

  - by Rakesh

  You have an N x N chessboard and you wish to place N kings on it. Each row and column should contain exactly one king, and no two kings should attack each other (two kings attack each other if they are present in squares which share a corner). The kings in the first K rows of the board have already been placed. You are given the positions of these kings as an array pos[ ]. pos[i] is the column in which the king in the ith row has already been placed. All indices are 0-indexed. In how many ways can the remaining kings be placed? Input: The first line contains the number of test cases T. T test cases follow. Each test case contains N and K on the first line, followed by a line having K integers, denoting the array pos[ ] as described above. Output: Output the number of ways to place kings in the remaining rows satisfying the above conditions. Output all numbers modulo 1000000007. Constraints: 1 <= T <= 20 1 <= N <= 16 0 <= K <= N 0 <= pos_i < N The kings specified in the input will be in different columns and not attack each other. Sample Input: 5 4 1 2 3 0 5 2 1 3 4 4 1 3 0 2 6 1 2 Sample Output: 1 0 2 1 18 Explanation: For the first example, there is a king already placed at row 0 and column 2. The king in the second row must belong to column 0. The king in the third row must belong to column 3, and the last king must beong to column 1. Thus there is only 1 valid placement. For the second example, there is no valid placement. How should i approach this problem

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• How to float a <div> echoed in the footer over a <div> located elsewhere (PHP/jQuery/HTML/CSS)

  - by PlasmaFlux

  Hello All! I'm embarking on a major project, but am stuck on a tiny issue at the very start. I'll try to be as concise as possible. I have a PHP script that will be echoing into the footer of the page (the last stuff before a bunch of s containing visible buttons and s containing hidden dialog boxes. The plan is to have the buttons float in the upper-right corner of corresponding s in the main content area of the page. i.e. - button-1 echoed into the footer will float in the corner of content-box-1, and will be tied to the hidden 'dialog-1'. I'll be using jQuery and jQuery UI Dialog throughout the page(s). I'm not sure if that's particularly relevant to this question, but thought it worth mentioning just in case. So my question, put simply, is how do I echo a Button 1 into the footer with PHP, but have it float in the upper-right corner (with maybe 5px margin) of Content 1 is full of content? A picture says a thousand words: As shown above, I want the little blue gear button things in the corner of content pieces, locked and loaded with hidden s containing dialog boxes. Again, the catch is that all buttons and hidden divs will be the very last items echoed into the page footer. I've found plenty of info on how to float divs on top of divs, but all the examples I saw showed the s in close proximity to each other in the page source; not with a hundred lines of source code between the two s I'm not sure if the solution is pure CSS, pure jQuery/jQueryUI or a combination of the two. Any advice will be much appreciated. Thanks!

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• How to join a table in symfony (Propel) and retrieve object from both table with one query

  - by Jean-Philippe

  Hi, I'm trying to get an easy way to fetch data from two joined Mysql table using Propel (inside Symfony) but in one query. Let's say I do this simple thing: $comment = CommentPeer::RetrieveByPk(1); print $comment->getArticle()->getTitle(); //Assuming the Article table is joined to the Comment table Symfony will call 2 queries to get that done. The first one to get the Comment row and the next one to get the Article row linked to the comment one. Now, I am trying to find a way to make all that within one query. I've tried to join them using $c = new Criteria(); $c->addJoin(CommentPeer::ARTICLE_ID, ArticlePeer::ID); $c->add(CommentPeer::ID, 1); $comment = CommentPeer::doSelectOne($c); But when I try to get the Article object using $comment->getArticle() It will still issue the query to get the Article row. I could easily clear all the selected columns and select the columns I need but that would not give me the Propel object I'd like, just an array of the query's raw result. So how can I get a populated propel object of two (or more) joined table with only one query? Thanks, JP

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• How to combine twill and python into one code that could be run on "Google App Engine"?

  - by brilliant

  Hello everybody!!! I have installed twill on my computer (having previously installed Python 2.5) and have been using it recently. Python is installed on disk C on my computer: C:\Python25 And the twill folder (“twill-0.9”) is located here: E:\tmp\twill-0.9 Here is a code that I’ve been using in twill: go “some website’s sign-in page URL” formvalue 2 userid “my login” formvalue 2 pass “my password” submit go “URL of some other page from that website” save_html result.txt This code helps me to log in to one website, in which I have an account, record the HTML code of some other page of that website (that I can access only after logging in), and store it in a file named “result.txt” (of course, before using this code I firstly need to replace “my login” with my real login, “my password” with my real password, “some website’s sign-in page URL” and “URL of some other page from that website” with real URLs of that website, and number 2 with the number of the form on that website that is used as a sign-in form on that website’s log-in page) This code I store in “test.twill” file that is located in my “twill-0.9” folder: E:\tmp\twill-0.9\test.twill I run this file from my command prompt: python twill-sh test.twill Now, I also have installed “Google App Engine SDK” from “Google App Engine” and have also been using it for awhile. For example, I’ve been using this code: import hashlib m = hashlib.md5() m.update("Nobody inspects") m.update(" the spammish repetition ") print m.hexdigest() This code helps me transform the phrase “Nobody inspects the spammish repetition” into md5 digest. Now, how can I put these two pieces of code together into one python script that I could run on “Google App Engine”? Let’s say, I want my code to log in to a website from “Google App Engine”, go to another page on that website, record its HTML code (that’s what my twill code does) and than transform this HTML code into its md5 digest (that’s what my second code does). So, how can I combine those two codes into one python code? I guess, it should be done somehow by importing twill, but how can it be done? Can a python code - the one that is being run by “Google App Engine” - import twill from somewhere on the internet? Or, perhaps, twill is already installed on “Google App Engine”?

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• Business entity: private instance VS single instance

  - by taoufik

  Suppose my WinForms application has a business entity Order, the entity is used in multiple views, each view handles a different domain or use-case in the application. As an example, one managing orders, the other one digging into one order and displaying additional data. If I'd use nHibernate (or any other ORM) and use one session/dataContext per view (or per db action), I'd end up getting two different instances for the same Order (let's say orderId = 1). Although functionally the same entity, they are technically two different instances. Yes, I could implement Equals/GetHashcode to make them "seem" the same. Why would you go for a single instance per entity vs private instances per view or per use-case? Having single instances has the advantage of sharing INotifyPropertyChanged events, and sharing additional (non-persistent) data. Having a private instance in each view would give you the flexibility of the undo functionality on a view level. In the example above, I'd allow the user to change order details, and give them the flexibility to not save the change. Here, synchronisation between the view/use-case happens on a data persistence level. What would your argument be?

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• Rails named_scope across multiple tables

  - by wakiki

  I'm trying to tidy up my code by using named_scopes in Rails 2.3.x but where I'm struggling with the has_many :through associations. I'm wondering if I'm putting the scopes in the wrong place... Here's some pseudo code below. The problem is that the :accepted named scope is replicated twice... I could of course call :accepted something different but these are the statuses on the table and it seems wrong to call them something different. Can anyone shed light on whether I'm doing the following correctly or not? I know Rails 3 is out but it's still in beta and it's a big project I'm doing so I can't use it in production yet. class Person < ActiveRecord::Base has_many :connections has_many :contacts, :through => :connections named_scope :accepted, :conditions => ["connections.status = ?", Connection::ACCEPTED] # the :accepted named_scope is duplicated named_scope :accepted, :conditions => ["memberships.status = ?", Membership::ACCEPTED] end class Group < ActiveRecord::Base has_many :memberships has_many :members, :through => :memberships end class Connection < ActiveRecord::Base belongs_to :person belongs_to :contact, :class_name => "Person", :foreign_key => "contact_id" end class Membership < ActiveRecord::Base belongs_to :person belongs_to :group end I'm trying to run something like person.contacts.accepted and group.members.accepted which are two different things. Shouldn't the named_scopes be in the Membership and Connection classes? One solution is to just call the two different named scope something different in the Person class or even to create separate associations (ie. has_many :accepted_members and has_many :accepted_contacts) but it seems hackish and in reality I have many more than just accepted (ie. banned members, ignored connections, pending, requested etc etc)

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• tabBarController and navigationControllers in landscape mode, episode II

  - by unforgiven

  I have a UITabBarController, and each tab handles a different UIViewController that pushes on the stack new controllers as needed. In two of these tabs I need, when a specific controller is reached, the ability to rotate the iPhone and visualize a view in landscape mode. After struggling a lot I have found that it is mandatory subclassing UITabBarController to override shouldAutorotateToInterfaceOrientation. However, if i simply return YES in the implementation, the following undesirable side effect arises: every controller in every tab is automatically put in landscape mode when rotating the iPhone. Even overriding shouldAutorotateToInterfaceOrientation in each controller to return NO does not work: when the iPhone is rotated, the controller is put in landscape mode. I implemented shouldAutorotateToInterfaceOrientation as follows in the subclassed UITabBarController: (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { if([self selectedIndex] == 0 || [self selectedIndex] == 3) return YES; return NO; } So that only the two tabs I am interested in actually get support for landscape mode. Is there a way to support landscape mode for a specific controller on the stack of a particular tab? I tried, without success, something like (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { if([self selectedIndex] == 0 || [self selectedIndex] == 3) { if ([[self selectedViewController] isKindOfClass: [landscapeModeViewController class]]) return YES; } return NO; } Also, I tried using the delegate method didSelectViewController, without success. Any help is greatly appreciated. Thank you.

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• Context Menu on QGraphicsWidget

  - by onurozcelik

  Hi, In my application I have two object type. One is field item, other is composite item. Composite items may contain two or more field items. Here is my composite item implementation. #include "compositeitem.h" CompositeItem::CompositeItem(QString id,QList<FieldItem *> _children) { children = _children; } CompositeItem::~CompositeItem() { } QRectF CompositeItem::boundingRect() const { //Not carefully thinked about it return QRectF(QPointF(-50,-150),QSizeF(250,250)); } void CompositeItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget ) { FieldItem *child; foreach(child,children) { child->paint(painter,option,widget); } } QSizeF CompositeItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const { QSizeF itsSize(0,0); FieldItem *child; foreach(child,children) { // if its size empty set first child size to itsSize if(itsSize.isEmpty()) itsSize = child->sizeHint(Qt::PreferredSize); else { QSizeF childSize = child->sizeHint(Qt::PreferredSize); if(itsSize.width() < childSize.width()) itsSize.setWidth(childSize.width()); itsSize.setHeight(itsSize.height() + childSize.height()); } } return itsSize; } void CompositeItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event) { qDebug()<<"Test"; } My first question is how I can propagate context menu event to specific child. Picture on the above demonstrates one of my possible composite item. If you look on the code above you will see that I print "Test" when context menu event occurs. When I right click on the line symbol I see that "Test" message is printed. But when I right click on the signal symbol "Test" is not printed and I want it to be printed. My second question what cause this behaviour. How do I overcome this.

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• Starting with versioning mysql schemata without overkill. Good solutions?

  - by tharkun

  I've arrived at the point where I realise that I must start versioning my database schemata and changes. I consequently read the existing posts on SO about that topic but I'm not sure how to proceed. I'm basically a one man company and not long ago I didn't even use version control for my code. I'm on a windows environment, using Aptana (IDE) and SVN (with Tortoise). I work on PHP/mysql projects. What's a efficient and sufficient (no overkill) way to version my database schemata? I do have a freelancer or two in some projects but I don't expect a lot of branching and merging going on. So basically I would like to keep track of concurrent schemata to my code revisions. [edit] Momentary solution: for the moment I decided I will just make a schema dump plus one with the necessary initial data whenever I'm going to commit a tag (stable version). That seems to be just enough for me at the current stage.[/edit] [edit2]plus I'm now also using a third file called increments.sql where I put all the changes with dates, etc. to make it easy to trace the change history in one file. from time to time I integrate the changes into the two other files and empty the increments.sql[/edit]

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• Using Linq2Sql to insert data into multiple tables using an auto incremented primary key

  - by Thomas

  I have a Customer table with a Primary key (int auto increment) and an Address table with a foreign key to the Customer table. I am trying to insert both rows into the database in one nice transaction. using (DatabaseDataContext db = new DatabaseDataContext()) { Customer newCustomer = new Customer() { Email = customer.Email }; Address b = new Address() { CustomerID = newCustomer.CustomerID, Address1 = billingAddress.Address1 }; db.Customers.InsertOnSubmit(newCustomer); db.Addresses.InsertOnSubmit(b); db.SubmitChanges(); } When I run this I was hoping that the Customer and Address table automatically had the correct keys in the database since the context knows this is an auto incremented key and will do two inserts with the right key in both tables. The only way I can get this to work would be to do SubmitChanges() on the Customer object first then create the address and do SubmitChanges() on that as well. This would create two roundtrips to the database and I would like to see if I can do this in one transaction. Is it possible? Thanks

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• Multi-accordion help (CSS issue maybe?)

  - by Josh

  So, I've been trying to develop this multi-accordion news section for this site. It's actually all working, thanks to an insightful plugin. I've modified it a little bit so it works as I want it to, but I've run into two issues, one which is possibly CSS. Issue #1: The idea for the user is that when they view this page, they see all the recent headlines. They can also see who it has been posted by and how many comments have been made to this article. If they wish, they can then click on the headline and the field will expand into the article. They can then either make a comment or view the comments via clicking the View Comments link or clicking the "number of comments" link in the "Posted by..." area (a shortcut to the comments basically). The problem I'm having is if I make the AUTHOR or the "0" comments a link, it breaks the accordion because the accordion uses an A CLASS to open it up. I'm looking for a fix, I've tried making it a H1 or a DIV but that also breaks it. Issue #2: This is a pretty picky one, but when you click the headline it expands, but at least in Firefox (haven't tested it in Chrome yet) the text jumps from the right and to the left, locking in place from which the CSS tells it to (padding-left). I don't know why it's exactly doing that, if anyone has any insight on that, it'd be appreciated. A two-parter to this issue is when you open the Headline to the article and then decide to close the article by clicking on the Headline, parts of the accordion jumps from the darker purple to the light purple before the task is finished. I'm also interested fixing this, but this issue in its entirety are all pretty nit picky things. You can view the demo of the site here: http://www.notedls.com/demo Please if anyone has any advice or fixes, I'd appreciate it, I've been trying to get this all to work to the best of my ability, but I'm clearly no guru or expert. Thanks!

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• Examples of monoids/semigroups in programming

  - by jkff

  It is well-known that monoids are stunningly ubiquitous in programing. They are so ubiquitous and so useful that I, as a 'hobby project', am working on a system that is completely based on their properties (distributed data aggregation). To make the system useful I need useful monoids :) I already know of these: Numeric or matrix sum Numeric or matrix product Minimum or maximum under a total order with a top or bottom element (more generally, join or meet in a bounded lattice, or even more generally, product or coproduct in a category) Set union Map union where conflicting values are joined using a monoid Intersection of subsets of a finite set (or just set intersection if we speak about semigroups) Intersection of maps with a bounded key domain (same here) Merge of sorted sequences, perhaps with joining key-equal values in a different monoid/semigroup Bounded merge of sorted lists (same as above, but we take the top N of the result) Cartesian product of two monoids or semigroups List concatenation Endomorphism composition. Now, let us define a quasi-property of an operation as a property that holds up to an equivalence relation. For example, list concatenation is quasi-commutative if we consider lists of equal length or with identical contents up to permutation to be equivalent. Here are some quasi-monoids and quasi-commutative monoids and semigroups: Any (a+b = a or b, if we consider all elements of the carrier set to be equivalent) Any satisfying predicate (a+b = the one of a and b that is non-null and satisfies some predicate P, if none does then null; if we consider all elements satisfying P equivalent) Bounded mixture of random samples (xs+ys = a random sample of size N from the concatenation of xs and ys; if we consider any two samples with the same distribution as the whole dataset to be equivalent) Bounded mixture of weighted random samples Which others do exist?

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• Templates, and C++ operator for logic: B contained by set A

  - by James Morris

  In C++, I'm looking to implement an operator for selecting items in a list (of type B) based upon B being contained entirely within A. In the book "the logical design of digital computers" by Montgomery Phister jr (published 1958), p54, it says: F11 = A + ~B has two interesting and useful associations, neither of them having much to do with computer design. The first is the logical notation of implication... The second is notation of inclusion... This may be expressed by a familiar looking relation, B < A; or by the statement "B is included in A"; or by the boolean equation F11= A + ~B = 1. My initial implementation was in C. Callbacks were given to the list to use for such operations. An example being a list of ints, and a struct containting two ints, min and max, for selection purposes. There, selection would be based upon B = A-min && B <= A-max. Using C++ and templates, how would you approach this after having implemented a generic list in C using void pointers and callbacks? Is using < as an over-ridden operator for such purposes... <ugh> evil? </ugh> (or by using a class B for the selection criteria, implementing the comparison by overloading ?)

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