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• A generic C++ library that provides QtConcurrent functionality?

  - by Lucas

  QtConcurrent is awesome. I'll let the Qt docs speak for themselves: QtConcurrent includes functional programming style APIs for parallel list processing, including a MapReduce and FilterReduce implementation for shared-memory (non-distributed) systems, and classes for managing asynchronous computations in GUI applications. For instance, you give QtConcurrent::map() an iterable sequence and a function that accepts items of the type stored in the sequence, and that function is applied to all the items in the collection. This is done in a multi-threaded manner, with a thread pool equal to the number of logical CPU's on the system. There are plenty of other function in QtConcurrent, like filter(), filteredReduced() etc. The standard CompSci map/reduce functions and the like. I'm totally in love with this, but I'm starting work on an OSS project that will not be using the Qt framework. It's a library, and I don't want to force others to depend on such a large framework like Qt. I'm trying to keep external dependencies to a minimum (it's the decent thing to do). I'm looking for a generic C++ framework that provides me with the same/similar high-level primitives that QtConcurrent does. AFAIK boost has nothing like this (I may be wrong though). boost::thread is very low-level compared to what I'm looking for. I know C# has something very similar with their Parallel Extensions so I know this isn't a Qt-only idea. What do you suggest I use?

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• PHP: Extract direct sub directory from path string

  - by Nebs

  I need to extract the name of the direct sub directory from a full path string. For example, say we have: $str = "dir1/dir2/dir3/dir4/filename.ext"; $dir = "dir1/dir2"; Then the name of the sub-directory in the $str path relative to $dir would be "dir3". Note that $dir never has '/' at the ends. So the function should be: $subdir = getsubdir($str,$dir); echo $subdir; // Outputs "dir3" If $dir="dir1" then the output would be "dir2". If $dir="dir1/dir2/dir3/dir4" then the output would be "" (empty). If $dir="" then the output would be "dir1". Etc.. Currently this is what I have, and it works (as far as I've tested it). I'm just wondering if there's a simpler way since I find I'm using a lot of string functions. Maybe there's some magic regexp to do this in one line? (I'm not too good with regexp unfortunately). function getsubdir($str,$dir) { // Remove the filename $str = dirname($str); // Remove the $dir if(!empty($dir)){ $str = str_replace($dir,"",$str); } // Remove the leading '/' if there is one $si = stripos($str,"/"); if($si == 0){ $str = substr($str,1); } // Remove everything after the subdir (if there is anything) $lastpart = strchr($str,"/"); $str = str_replace($lastpart,"",$str); return $str; } As you can see, it's a little hacky in order to handle some odd cases (no '/' in input, empty input, etc). I hope all that made sense. Any help/suggestions are welcome.

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• How do I execute queries upon DB connection in Rails?

  - by sycobuny

  I have certain initializing functions that I use to set up audit logging on the DB server side (ie, not rails) in PostgreSQL. At least one has to be issued (setting the current user) before inserting data into or updating any of the audited tables, or else the whole query will fail spectacularly. I can easily call these every time before running any save operation in the code, but DRY makes me think I should have the code repeated in as few places as possible, particularly since this diverges greatly from the ideal of database agnosticism. Currently I'm attempting to override ActiveRecord::Base.establish_connection in an initializer to set it up so that the queries are run as soon as I connect automatically, but it doesn't behave as I expect it to. Here is the code in the initializer: class ActiveRecord::Base # extend the class methods, not the instance methods class << self alias :old_establish_connection :establish_connection # hide the default def establish_connection(*args) ret = old_establish_connection(*args) # call the default # set up necessary session variables for audit logging # call these after calling default, to make sure conn is established 1st db = self.class.connection db.execute("SELECT SV.set('current_user', 'test@localhost')") db.execute("SELECT SV.set('audit_notes', NULL)") # end "empty variable" err ret # return the default's original value end end end puts "Loaded custom establish_connection into ActiveRecord::Base" sycobuny:~/rails$ ruby script/server = Booting WEBrick = Rails 2.3.5 application starting on http://0.0.0.0:3000 Loaded custom establish_connection into ActiveRecord::Base This doesn't give me any errors, and unfortunately I can't check what the method looks like internally (I was using ActiveRecord::Base.method(:establish_connection), but apparently that creates a new Method object each time it's called, which is seemingly worthless cause I can't check object_id for any worthwhile information and I also can't reverse the compilation). However, the code never seems to get called, because any attempt to run a save or an update on a database object fails as I predicted earlier. If this isn't a proper way to execute code immediately on connection to the database, then what is?

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• Speed comparison - Template specialization vs. Virtual Function vs. If-Statement

  - by Person

  Just to get it out of the way... Premature optimization is the root of all evil Make use of OOP etc. I understand. Just looking for some advice regarding the speed of certain operations that I can store in my grey matter for future reference. Say you have an Animation class. An animation can be looped (plays over and over) or not looped (plays once), it may have unique frame times or not, etc. Let's say there are 3 of these "either or" attributes. Note that any method of the Animation class will at most check for one of these (i.e. this isn't a case of a giant branch of if-elseif). Here are some options. 1) Give it boolean members for the attributes given above, and use an if statement to check against them when playing the animation to perform the appropriate action. Problem: Conditional checked every single time the animation is played. 2) Make a base animation class, and derive other animations classes such as LoopedAnimation and AnimationUniqueFrames, etc. Problem: Vtable check upon every call to play the animation given that you have something like a vector<Animation>. Also, making a separate class for all of the possible combinations seems code bloaty. 3) Use template specialization, and specialize those functions that depend on those attributes. Like template<bool looped, bool uniqueFrameTimes> class Animation. Problem: The problem with this is that you couldn't just have a vector<Animation> for something's animations. Could also be bloaty. I'm wondering what kind of speed each of these options offer? I'm particularly interested in the 1st and 2nd option because the 3rd doesn't allow one to iterate through a general container of Animations. In short, what is faster - a vtable fetch or a conditional?

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• Protocol specification in XML

  - by Mathijs

  Is there a way to specify a packet-based protocol in XML, so (de)serialization can happen automatically? The context is as follows. I have a device that communicates through a serial port. It sends and receives a byte stream consisting of 'packets'. A packet is a collection of elementary data types and (sometimes) other packets. Some elements of packets are conditional; their inclusion depends on earlier elements. I have a C# application that communicates with this device. Naturally, I don't want to work on a byte-level throughout my application; I want to separate the protocol from my application code. Therefore I need to translate the byte stream to structures (classes). Currently I have implemented the protocol in C# by defining a class for each packet. These classes define the order and type of elements for each packet. Making class members conditional is difficult, so protocol information ends up in functions. I imagine XML that looks like this (note that my experience designing XML is limited): <packet> <field name="Author" type="int32" /> <field name="Nickname" type="bytes" size="4"> <condition type="range"> <field>Author</field> <min>3</min> <max>6</min> </condition> </field> </packet> .NET has something called a 'binary serializer', but I don't think that's what I'm looking for. Is there a way to separate protocol and code, even if packets 'include' other packets and have conditional elements?

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• What is the best way to store static data in C# that will never changes

  - by Luke101

  I have a class that stores data in asp.net c# application that never changes. I really don't want to put this data in the database - I would like it to stay in the application. Here is my way to store data in the application: public class PostVoteTypeFunctions { private List<PostVoteType> postVotes = new List<PostVoteType>(); public PostVoteTypeFunctions() { PostVoteType upvote = new PostVoteType(); upvote.ID = 0; upvote.Name = "UpVote"; upvote.PointValue = PostVotePointValue.UpVote; postVotes.Add(upvote); PostVoteType downvote = new PostVoteType(); downvote.ID = 1; downvote.Name = "DownVote"; downvote.PointValue = PostVotePointValue.DownVote; postVotes.Add(downvote); PostVoteType selectanswer = new PostVoteType(); selectanswer.ID = 2; selectanswer.Name = "SelectAnswer"; selectanswer.PointValue = PostVotePointValue.SelectAnswer; postVotes.Add(selectanswer); PostVoteType favorite = new PostVoteType(); favorite.ID = 3; favorite.Name = "Favorite"; favorite.PointValue = PostVotePointValue.Favorite; postVotes.Add(favorite); PostVoteType offensive = new PostVoteType(); offensive.ID = 4; offensive.Name = "Offensive"; offensive.PointValue = PostVotePointValue.Offensive; postVotes.Add(offensive); PostVoteType spam = new PostVoteType(); spam.ID = 0; spam.Name = "Spam"; spam.PointValue = PostVotePointValue.Spam; postVotes.Add(spam); } } When the constructor is called the code above is ran. I have some functions that can query the data above too. But is this the best way to store information in asp.net? if not what would you recommend?

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• How can I avoid encoding mixups of strings in a C/C++ API?

  - by Frerich Raabe

  I'm working on implementing different APIs in C and C++ and wondered what techniques are available for avoiding that clients get the encoding wrong when receiving strings from the framework or passing them back. For instance, imagine a simple plugin API in C++ which customers can implement to influence translations. It might feature a function like this: const char *getTranslatedWord( const char *englishWord ); Now, let's say that I'd like to enforce that all strings are passed as UTF-8. Of course I'd document this requirement, but I'd like the compiler to enforce the right encoding, maybe by using dedicated types. For instance, something like this: class Word { public: static Word fromUtf8( const char *data ) { return Word( data ); } const char *toUtf8() { return m_data; } private: Word( const char *data ) : m_data( data ) { } const char *m_data; }; I could now use this specialized type in the API: Word getTranslatedWord( const Word &englishWord ); Unfortunately, it's easy to make this very inefficient. The Word class lacks proper copy constructors, assignment operators etc.. and I'd like to avoid unnecessary copying of data as much as possible. Also, I see the danger that Word gets extended with more and more utility functions (like length or fromLatin1 or substr etc.) and I'd rather not write Yet Another String Class. I just want a little container which avoids accidental encoding mixups. I wonder whether anybody else has some experience with this and can share some useful techniques. EDIT: In my particular case, the API is used on Windows and Linux using MSVC 6 - MSVC 10 on Windows and gcc 3 & 4 on Linux.

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• Why should I abstract my data layer?

  - by Gazillion

  OOP principles were difficult for me to grasp because for some reason I could never apply them to web development. As I developed more and more projects I started understanding how some parts of my code could use certain design patterns to make them easier to read, reuse, and maintain so I started to use it more and more. The one thing I still can't quite comprehend is why I should abstract my data layer. Basically if I need to print a list of items stored in my DB to the browser I do something along the lines of: $sql = 'SELECT * FROM table WHERE type = "type1"';' $result = mysql_query($sql); while($row = mysql_fetch_assoc($result)) { echo '<li>'.$row['name'].'</li>'; } I'm reading all these How-Tos or articles preaching about the greatness of PDO but I don't understand why. I don't seem to be saving any LoCs and I don't see how it would be more reusable because all the functions that I call above just seem to be encapsulated in a class but do the exact same thing. The only advantage I'm seeing to PDO are prepared statements. I'm not saying data abstraction is a bad thing, I'm asking these questions because I'm trying to design my current classes correctly and they need to connect to a DB so I figured I'd do this the right way. Maybe I'm just reading bad articles on the subject :) I would really appreciate any advice, links, or concrete real-life examples on the subject!

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• Calling a WPF Appliaction and modify exposed properties?

  - by Justin

  I have a WPF Keyboard Application, it is developed in such a way that an application could call it and modify its properties to adapt the Keyboard to do what it needs to. Right now I have a file *.Keys.Set which tells the appliaction (on open) to style itself according to that new style. I know this file could be passed as a command line argument into the appliaction. That would not be a problem. My concern is, is thier a way via a managed environment to change the properties of the executable as long as they are exposed properly, an example: 'Creates a new instance of the Keyboard Appliaction Dim e_key as new WpfAppliaction("C:\egt\components\keyboard.exe") 'Sets the style path e_key.SetStylePath("c:\users\joe\apps\me\default.keys.set") e_key.Refresh() 'Applies the style e_key.HideMenu() 'Hides the menu e_key.ShowDeck("PIN") 'Shows the custom "deck" of keyboard keys the developer 'Created in the style appliaction. ''work with events and resposne 'Clear the instance from memory e_key.close e_key.dispose e_key = nothing This would allow my application to become easily accessible to other Touch Screen Application Developers, allowing them to use my key_board and keep the functionality they need. It seems like it might be possible because (name of executable).application shows all the exposed functions, properties, and values. I just have never done this before. Any help would be appreciated, thank you in advance.

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• Simple jQuery syntax help, don't know where I've gone wrong

  - by Jascination

  I'm having trouble with a jQuery code at the moment, I know WHERE the problem lies, but I don't know what the problem is exactly. Probably very basic, but I'm new to this. You can see a (non)working fiddle here: http://www.jsfiddle.net/CvZeQ/ Basically I want to set different .click function based on whatever is selected (I have 5 image maps, each with a different #mapname, and want each to pertain to a different variable (answer1, answer2, answer3...) so as to store the selected 'answer' for each map.) Here is the code I'm using for one of the maps: $(window).load(function(){ //Get cookies when page loaded var useranswers=$.cookie('survery'); useranswers= JSON.parse (useranswers); // do something with previous answers //#shape functions $('#shape area').hover( function(e){ $('#'+ this.alt).addClass('hover'); }, function(e){ $('#'+ this.alt).removeClass('hover'); } ).click( function(e){ $('img.selected-region').removeClass('selected-region'); }, function(e){ $('#'+ this.alt).addClass('selected-region'); }, function(e){ var answer1 = $(this).attr("class"); }); }); I know the problem lies somewhere with the .click function, but I'm not entirely sure what I've done wrong. Any help would be greatly appreciated.

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• Logging in to website with saved username and password

  - by DGund

  One of the functions of an app I am making involves logging the user into our Campus Portal website. For ease of use, the user may enter a username and password into the app once, and it will be saved for all future log-ins. When the user clicks a button, the information will automatically be sent to log in, and the website will be displayed in a UIWebView. Let us say that the username and password are each stored in an NSString. How can I use this data to log in to this website programmatically and display the page it in a UIWebView? I know little about posting and forms, so any help is appreciated. Would something like this Stackoverflow answer help? Here's the shell of my code for this - (IBAction)btnGo:(id)sender { username = usernameField.text; password = passwordField.text; if (saveSwitch.isOn) { //Save data if the user wants AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate]; usernameSaved = username; passwordSaved = password; [appDelegate.listOfPortalCredentials replaceObjectAtIndex:0 withObject:usernameSaved]; [appDelegate.listOfPortalCredentials replaceObjectAtIndex:1 withObject:passwordSaved]; } //Insert username and password to web form, log in to portal //This is where I need help }

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• Passing functor and function pointers interchangeably using a templated method in C++

  - by metroxylon

  I currently have a templated class, with a templated method. Works great with functors, but having trouble compiling for functions. Foo.h template <typename T> class Foo { public: // Constructor, destructor, etc... template <typename Func> void bar(T x, Func f); }; template <typename T> template <typename Func> Foo::bar(T x, Func f) { /* some code here */ } Main.cpp #include "Foo.h" template <typename T> class Functor { public: Functor() {} void operator()(T x) { /* ... */ } private: /* some attributes here */ }; void Function(T x) { /* ... */ } int main() { Foo<int> foo; foo.bar(2, Functor); // No problem foo.bar(2, Function); // <unresolved overloaded function type> return 0; }

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• Bootstrap inline button dropdown within <p> jumbotron

  - by C.B.

  Currently I have a jumbotron setup with some paragraph text, and I would like to stick a button dropdown inline with the text. Dropdown button <span class="btn-group"> <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown"> Button... <span class="caret"></span> </button> <ul class="dropdown-menu" role="menu"> <li><a href="#">Opt 1</a></li> <li><a href="#">Opt 2</a></li> </ul> </span> Jumbotron <div class="jumbotron"> <h1>Hello!</h1> <p>Welcome</p> <p>Another paragraph <!-- dropdown is here --> </p> </div> <!-- jumbotron --> If the dropdown is within the <p> tag, it does not "dropdown" (but renders). If it is outside of the <p> tag it functions fine, but I would like it to be inline with the text and need the text to be in the <p> tag to get the style. Any ideas? Things to note -- If I replace the <span> tags with <div> tags, it will work fine within the <p> tags, but won't be inline.

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• Best suited tool to document message processing done in C written program

  - by user3494614

  I am relatively new to UML and it's seems to be very vast I have a small program which basically receives messages on socket and then depending upon message ID embedded as first byte of message it processes the buffer. There are around 5 different message ID which it processes and communicates on another socket and has around 8 major functions. So program in short is like this. I am not pasting entire .c file or main function but just giving some bits and pieces of it so that to get idea of program flow. int main(int argc, char** argv) { register_shared_mem(); listen(); while(get_next_message(buffer)) { switch((msg)(buffer)->id) { case TYPE1: process1(); answer(); ..... } } } I want to document this is pictorial way like for Message type 1 it calls this function which calls another and which calls another. Please let me know any open source tool which will allow me to quickly draw such kind of UML or sequence diagram and will also allow me to write brief description of what each function does? Thanks In Advance

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• Parsing localized date strings in PHP

  - by Mikeage

  Hi, I have some code (it's part of a wordpress plugin) which takes a text string, and the format specifier given to date(), and attempts to parse it into an array containing hour, minute, second, day, month, year. Currently, I use the following code (note that strtotime is horribly unreliable with things like 01/02/03) // $format contains the string originally given to date(), and $content is the rendered string if (function_exists('date_parse_from_format')) { $content_parsed = date_parse_from_format($format, $content); } else { $content = preg_replace("([0-9]st|nd|rd|th)","\\1",$content); $content_parsed = strptime($content, dateFormatToStrftime($format)); $content_parsed['hour']=$content_parsed['tm_hour']; $content_parsed['minute']=$content_parsed['tm_min']; $content_parsed['day']=$content_parsed['tm_mday']; $content_parsed['month']=$content_parsed['tm_mon'] + 1; $content_parsed['year']=$content_parsed['tm_year'] + 1900; } This actually works fairly well, and seems to handle every combination I've thrown at it. However, recently someone gave me 24 ??????, 2010. This is Russian for November 24, 2010 [the date format was j F, Y], and it is parsed as year = 2010, month = null, day = 24. Are there any functions that I can use that know how to translate both November and ?????? into 11? EDIT: Running print_r(setlocale(LC_ALL, 0)); returns C. Switching back to strptime() seems to fix the problem, but the docs warn: Internally, this function calls the strptime() function provided by the system's C library. This function can exhibit noticeably different behaviour across different operating systems. The use of date_parse_from_format(), which does not suffer from these issues, is recommended on PHP 5.3.0 and later. Is date_parse_from_format() the correct API, and if so, how do I get it to recognize the language?

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• Blocking HTML and Javascript from being displayed on my site

  - by Tim Powell

  I am working on this new social networking site. One of it's various functions is posting. You can post to Facebook and my site, or Twitter and my site. That being said, I couldn't help but try and post HTML as I was testing sql injection. When I did, I noticed that there where ways to manipulate the site to, for instance, using a element to completely screw up the CSS design, or redirect a user to another site using javascript. That being said, I want to make my site a safe environment for my users... not a site that is used to distribute computer viruses, porn, and other things that might make someone tend to stay off of my site. When I searched this topic, I found ways to "strip" the HTML out of the $post variable before submitting it to the database. However, I would just like to make it so you can post any text, including HTML and Javascript, without the browser interpreting it as "run this..." code: I want to display it as plane text. I've seen it on Facebook, and when I looked at it the source code of a post, it showed <, /, and as regular text. I tried "dissecting" Facebook's source code, but found nothing. I have tried using tags such as <pre> and <code>, but because of the lack of ability to style and control them, I gave up and went back to just allowing HTML. Please, anyone who knows how to do this, please help me out. Thanks in advance, TP

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• Recommended approach for error handling with PHP and MYSQL

  - by iama

  I am trying to capture database (MYSQL) errors in my PHP web application. Currently, I see that there are functions like mysqli_error(), mysqli_errno() for capturing the last occurred error. However, this still requires me to check for error occurrence using repeated if/else statements in my php code. You may check my code below to see what I mean. Is there a better approach to doing this? (or) Should I write my own code to raise exceptions and catch them in one single place? What is the recommended approach? Also, does PDO raise exceptions? Thanks. function db_userexists($name, $pwd, &$dbErr) { $bUserExists = false; $uid = 0; $dbErr = ''; $db = new mysqli(SERVER, USER, PASSWORD, DB); if (!mysqli_connect_errno()) { $query = "select uid from user where uname = ? and pwd = ?"; $stmt = $db->prepare($query); if ($stmt) { if ($stmt->bind_param("ss", $name, $pwd)) { if ($stmt->bind_result($uid)) { if ($stmt->execute()) { if ($stmt->fetch()) { if ($uid) $bUserExists = true; } } } } if (!$bUserExists) $dbErr = $db->error(); $stmt->close(); } if (!$bUserExists) $dbErr = $db->error(); $db->close(); } else { $dbErr = mysqli_connect_error(); } return $bUserExists; }

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• How can I write to a single xml file from two programs at the same time?

  - by Tom Bushell

  We recently started working with XML files, after many years of experience with the old INI files. My coworker found some CodeProject sample code that uses System.Xml.XmlDocument.Save. We are getting exceptions when two programs try to write to the same file at the same time. System.IO.IOException: The process cannot access the file 'C:\Test.xml' because it is being used by another process. This seems obvious in hindsight, but we had not anticipated it because accessing INI files via the Win32 API does not have this limitation. I assume there's some arbitration done by the Win32 calls that work at a higher level than the the XmlDocument.Save method. I'm hoping there are higher level XML routines somewhere in the .Net library that work similarily to the Win32 functions, but don't know where to start looking. Or maybe we can set up our file access permissions to allow multiple programs to write to the same file? Time is short (like almost all SW projects), and if we can't find a solution quickly, we'll have to hold our noses and go back to INI files.

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• what patern is layerd architechture in asp.net ?

  - by haansi

  Hi, I am a asp.net developer and don't know much about patterns and architecture. I will very thankful if you can please guide me here. In my web applications I use 4 layers. Web site project (having web forms + code behind cs files, user controls + code behind cs files, master pages + code behind cs files) CustomTypesLayer a class library (having custom types, enumerations, DTOs, constructers, get, set and validations) BusinessLogicLayer a class library (having all business logic, rules and all calls to DAL functions) DataAccessLayer a class library( having just classes communicating to database.) -My user interface just calls BusinessLogicLayer. BusinessLogicLayer do proecessign in it self and for data it calls DataAccessLayer funtions. -Web forms do not calls directly DAL. -CustomTypesLayer is shared by all layers. Please guide me is this approach a pattern ? I though it may be MVC or MVP but pages have there code behind files as well which are confusing me. If it is no patren is it near to some patren ? pleaes guide thanks

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• zend-framework doctrine, and mvc pattern: what should connect data between models and forms?

  - by Skirmantas

  I am learning Zend Framework and Doctrine. I am wondering what is the best practice to connect forms to models and vice versa. I don't know where I should put my code. I have seen in Zendcast video tutorials where author creates methods like mapFormToRecord and mapRecordToForm in form class. Well I guess it is very handy when form is sophisticated and uses many records. Is it a good practice? I somehow believe that form-class should not need to know about data-records. And sometimes we might have model which is used in many forms. So It would be handy to have few functions in that model which would help to prepare data for forms. For example to give an array of id=name pairs so that it might be used in Zend_Form_Element_Select. However I would like to have a consistency. So I don't want to put this code nor in model nor in form because on different situations I act different. So only controller is what is left to deal it. However this will result in code duplication if one form will be used more than in one controller. Moreover controller gets bloated if form is not from the simple ones. Or maybe there is a consistent pattern in those data conversions between forms and models? I think that there is. At least in my simple cases. So maybe a separate class could be a solution? Where should I put such class and how should I name it? Another question: Zend_Form has validators and filter. Doctrine has validators and filters too. Which do we use and when? What is your way of dealing the connections between forms and models? (Sorry if it was hard for you to read my text. I don't have enough knowledge of English language to express myself freely)

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• R optimization: How can I avoid a for loop in this situation?

  - by chrisamiller

  I'm trying to do a simple genomic track intersection in R, and running into major performance problems, probably related to my use of for loops. In this situation, I have pre-defined windows at intervals of 100bp and I'm trying to calculate how much of each window is covered by the annotations in mylist. Graphically, it looks something like this: 0 100 200 300 400 500 600 windows: |-----|-----|-----|-----|-----|-----| mylist: |-| |-----------| So I wrote some code to do just that, but it's fairly slow and has become a bottleneck in my code: ##window for each 100-bp segment windows <- numeric(6) ##second track mylist = vector("list") mylist[[1]] = c(1,20) mylist[[2]] = c(120,320) ##do the intersection for(i in 1:length(mylist)){ st <- floor(mylist[[i]][1]/100)+1 sp <- floor(mylist[[i]][2]/100)+1 for(j in st:sp){ b <- max((j-1)*100, mylist[[i]][1]) e <- min(j*100, mylist[[i]][2]) windows[j] <- windows[j] + e - b + 1 } } print(windows) [1] 20 81 101 21 0 0 Naturally, this is being used on data sets that are much larger than the example I provide here. Through some profiling, I can see that the bottleneck is in the for loops, but my clumsy attempt to vectorize it using *apply functions resulted in code that runs an order of magnitude more slowly. I suppose I could write something in C, but I'd like to avoid that if possible. Can anyone suggest another approach that will speed this calculation up?

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• Fortran pointer as an argument to interface procedure

  - by icarusthecow

  Im trying to use interfaces to call different subroutines with different types, however, it doesnt seem to work when i use the pointer attribute. for example, take this sample code MODULE ptr_types TYPE, abstract :: parent INTEGER :: q END TYPE TYPE, extends(parent) :: child INTEGER :: m END TYPE INTERFACE ptr_interface MODULE PROCEDURE do_something END INTERFACE CONTAINS SUBROUTINE do_something(atype) CLASS(parent), POINTER :: atype ! code determines that this allocation is correct from input ALLOCATE(child::atype) WRITE (*,*) atype%q END SUBROUTINE END MODULE PROGRAM testpass USE ptr_types CLASS(child), POINTER :: ctype CALL ptr_interface(ctype) END PROGRAM This gives error Error: There is no specific subroutine for the generic 'ptr_interface' at (1) however if i remove the pointer attribute in the subroutine it compiles fine. Now, normally this wouldnt be a problem, but for my use case i need to be able to treat that argument as a pointer, mainly so i can allocate it if necessary. Any suggestions? Mind you I'm new to fortran so I may have missed something edit: forgot to put the allocation in the parents subroutine, the initial input is unallocated EDIT 2 this is my second attempt, with caller side casting MODULE ptr_types TYPE, abstract :: parent INTEGER :: q END TYPE TYPE, extends(parent) :: child INTEGER :: m END TYPE TYPE, extends(parent) :: second INTEGER :: meow END TYPE CONTAINS SUBROUTINE do_something(this, type_num) CLASS(parent), POINTER :: this INTEGER type_num IF (type_num == 0) THEN ALLOCATE (child::this) ELSE IF (type_num == 1) THEN ALLOCATE (second::this) ENDIF END SUBROUTINE END MODULE PROGRAM testpass USE ptr_types CLASS(child), POINTER :: ctype SELECT TYPE(ctype) CLASS is (parent) CALL do_something(ctype, 0) END SELECT WRITE (*,*) ctype%q END PROGRAM however this still fails. in the select statement it complains that parent must extend child. Im sure this is due to restrictions when dealing with the pointer attribute, for type safety, however, im looking for a way to convert a pointer into its parent type for generic allocation. Rather than have to write separate allocation functions for every type and hope they dont collide in an interface or something. hopefully this example will illustrate a little more clearly what im trying to achieve, if you know a better way let me know

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• Setting up a view to draw to in Objective-C (iPhone) ?

  - by Johannes Jensen

  Okay, so, I'm all new to iPhone and stuff, but I'm not even at programming, I have many years of experience with ActionScript 2.0 and 3.0, I want to set up a view, that I can also pass variables to. The view is gonna draw everything with Quartz. I tried to make another game where I tried to add a pointer to a NSMutableArray to the view class, but it didn't work cause I didn't know how to store an actual class. I wanted to do like: [myView setNeedsDisplay]; but I had to do [(View*)self.view setNeedsDisplay]; didn't really work out in the end... Okay, so now I got: - (void) viewDidLoad { [super viewDidLoad]; viewClass = [[View class] retain]; gameView = [[[viewClass alloc] initWithFrame: CGRectZero] retain]; [gameView setNeedsDisplay]; } This is in my drawInContext:context, which is fired by drawRect: Also, my drawRect does [self drawInContext: UIGraphicsGetCurrentContext()]; CGContextSetStrokeColorWithColor(context, [[UIColor blackColor] CGColor]); CGContextSetLineWidth(context, 3.0); CGContextSetLineCap(context, kCGLineCapRound); CGContextSetLineJoin(context, kCGLineJoinRound); CGMutablePathRef aPath = CGPathCreateMutable(); CGPathMoveToPoint(aPath, nil, 5, 5); CGPathAddLineToPoint(aPath, nil, 45, 43); CGContextAddPath(context, aPath); CGContextStrokePath(context); Nothing happens. Help? Oh yeah, I get this error: : invalid context for each time I use those functions. :[ Thanks!

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• Embedded scripting engine in .Net app

  - by Nate

  I am looking to replace an old control being used for scripting an application. The control used to be called SAX Basic, but is now called WinWrap. It provides us with two primary functions. 1) It's a scripting engine (VB) 2) It has a GUI for developing and debugging scripts that get run in the hosting application. The first feature it provides is actually pretty easy to replace. There are so many great methods of running just about any kind of code at runtime that it's almost a non-issue. Just about any language targeting the .Net runtime will work for us. We've looked at running C#, PowerShell, VB.Net, IronPython, etc. I've also taken a brief look at Lua and F#, but honestly the language isn't the biggest barrier here. Now, for the hard part that seems to keep getting me stuck. We want a code editor, and debugger. Something simple, not unlike PowerShell's ISE would be fine. Just as long as a file could be created, saved, debugged and executed. I'm currently looking into Visual Studio 2010 Shell (Isolated) and I'm also looking at the feasibility of embedding PowerShell ISE in my application. Are there any other editor's I could embed/use in my application? Purchasing a product is not out of the question. It comes down to a combination of ease of use, how well it meets our needs, and how simple deployment and licensing is for developers. Thanks for the pointers

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• callback on a variable which is inside a .each() loop

  - by Stoic

  I have this function, which is doing an asynchronous call to FB.api method. Now, i am looping over some data and capturing result of the above method call successfully. However, I am using a .each loop and I really can not figure out how to place my callback in this method, so that the outer method is only executed once. Here are the functions I am using: ask_for_perms($(this).val(),function(result) { $('#some-div').html('<a onclick = "get_perms(result);" >get perms</a>'); }); function ask_for_perms(perms_requested,cb) { var request = []; $.each(perms_requested,function(i,permission) { FB.api({ method: 'users.hasAppPermission', ext_perm: permission }, function(response) { if (response == 0) request.push(permission); request.join(','); cb(request); // cb is called many times here. }); }); } I am trying to return the request string from ask_for_perms function. Can anyone suggest me on where to place a proper callback to ask_for_perms. Right now, however, it works for me, but the callback is being called many times since it is inside a for loop. referencing: returning a variable from the callback of a function

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