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RichFaces a4j:support parameter passing

- by Mark Lewis

Hello I have a number of rich:inplaceInput tags in RichFaces which represent numbers in an array. The validator allows integers only. When a user clicks in an input and changes a value, how can I get the bean to sort the array given the new number and reRender the list of rich:inplaceInput tags so that they're in numerical order? EG <a4j:region> <rich:dataTable value="#{MyBacking.config}" var="feed" cellpadding="0" cellspacing="0" width="100%" border="0" columns="5" id="Admin"> ... <a4j:repeat... <a4j:region id="MsgCon"> <rich:inplaceInput value="#{h.id}" validator="#{MyBacking.validateID}" id="andID" showControls="true"> <a4j:support event="onviewactivated" action="#{MyBacking.sort}" reRender="Admin" /> </rich:inplaceInput> </a4j:region> </a4j:repeat> </data:Table> </a4j:region> Note I do NOT want to use dataTable sort functions. The table is complicated and I've specified id="Admin" (ie the whole table) to reRender as I've not found a way to send more localised values to the backing bean through the inplaceInput. This question is about how to use a4j:support action attribute to call the sort method so that when the reRender rerenders the component, it outputs the list in sorted order. I have the sort method working ok when I click a button to sort, but I want to have the list sorted automatically as soon as a new valid value is entered into the inplaceInput component. Thanks

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Function with parameter type that has a copy-constructor with non-const ref chosen?

- by Johannes Schaub - litb

Some time ago I was confused by the following behavior of some code when I wanted to write a is_callable<F, Args...> trait. Overload resolution won't call functions accepting arguments by non-const ref, right? Why doesn't it reject in the following because the constructor wants a Test&? I expected it to take f(int)! struct Test { Test() { } // I want Test not be copyable from rvalues! Test(Test&) { } // But it's convertible to int operator int() { return 0; } }; void f(int) { } void f(Test) { } struct WorksFine { }; struct Slurper { Slurper(WorksFine&) { } }; struct Eater { Eater(WorksFine) { } }; void g(Slurper) { } void g(Eater) { } // chooses this, as expected int main() { // Error, why? f(Test()); // But this works, why? g(WorksFine()); } Error message is m.cpp: In function 'int main()': m.cpp:33:11: error: no matching function for call to 'Test::Test(Test)' m.cpp:5:3: note: candidates are: Test::Test(Test&) m.cpp:2:3: note: Test::Test() m.cpp:33:11: error: initializing argument 1 of 'void f(Test)' Can you please explain why one works but the other doesn't?

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Corrupt UTF-8 Characters with PHP 5.2.10 and MySQL 5.0.81

- by jkndrkn

We have an application hosted on both a local development server and a live site. We are experiencing UTF-8 corruption issues and are looking to figure out how to resolve them. The system is run using symfony 1.0 with Propel. On our development server, we are running PHP 5.2.0 and MySQL 5.0.32. We do not experience corrupted UTF-8 characters there. On our live site, PHP 5.2.10 and MySQL 5.0.81 is running. On that server, certain characters such as ô´ and S are corrupted once they are stored in the database. The corrupted characters are showing up as either question marks or approximations of the original character with adjacent question marks. Examples of corruption: Uncorrupted: ô´ Corrupted: ô? Uncorrupted: S Corrupted: ? We are currently using the following techniques on both development and live servers: Executing the following queries prior to execution of any other queries: SET NAMES 'utf8' COLLATE 'utf8_unicode_ci' SET CHARSET 'utf8' Setting the <meta> Content-Type value to: <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> Adding the following to our .htaccess file: AddDefaultCharset utf-8 Using mb_* (multibyte) PHP functions where necessary. Being sure to set database columns to use utf8_unicode_ci collation. These techniques are sufficient for our development site, but do not work on the live site. On the live site I've also tried adding mysql_set_encoding('ut8', $mysql_connection) but this does not help either. I have found some evidence that newer versions of PHP and MySQL are mishandling UTF-8 character encodings.

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How can I obtain the local TCP port and IP Address of my client program?

- by Dr Dork

Hello! I'm prepping for a simple work project and am trying to familiarize myself with the basics of socket programming in a Unix dev environment. At this point, I have some basic server side code and client side code setup to communicate. Currently, my client code successfully connects to the server code and the server code sends it a test message, then both quit out. Perfect! That's exactly what I wanted to accomplish. Now I'm playing around with the functions used to obtain info about the two environments (server and client). I'd like to obtain the local IP address and dynamically assigned TCP port of the client. The function I've found to do this is getsockname()... //setup the socket if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) { perror("client: socket"); continue; } //Retrieve the locally-bound name of the specified socket and store it in the sockaddr structure sa_len = sizeof(sa); getsock_check = getsockname(sockfd,(struct sockaddr *)&sa,(socklen_t *)&sa_len) ; if (getsock_check== -1) { perror("getsockname"); exit(1); } printf("Local IP address is: %s\n", inet_ntoa(sa.sin_addr)); printf("Local port is: %d\n", (int) ntohs(sa.sin_port)); but the output is always zero... Local IP address is: 0.0.0.0 Local port is: 0 does anyone see anything I might be or am definitely doing wrong? Thanks so much in advance for all your help!

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Hibernate: Walk millions of rows and don't leak memory

- by Autocracy

The below code functions, but Hibernate never lets go of its grip of any object. Calling session.clear() causes exceptions regarding fetching a joined class, and calling session.evict(currentObject) before retrieving the next object also fails to free the memory. Eventually I exhaust my heap space. Checking my heap dumps, StatefulPersistenceContext is the garbage collector's root for all references pointing to my objects. public class CriteriaReportSource implements JRDataSource { private ScrollableResults sr; private Object currentObject; private Criteria c; private static final int scrollSize = 10; private int offset = 1; public CriteriaReportSource(Criteria c) { this.c = c; advanceScroll(); } private void advanceScroll() { // ((Session) Main.em.getDelegate()).clear(); this.sr = c.setFirstResult(offset) .setMaxResults(scrollSize) .scroll(ScrollMode.FORWARD_ONLY); offset += scrollSize; } public boolean next() { if (sr.next()) { currentObject = sr.get(0); if (sr.isLast()) { advanceScroll(); } return true; } return false; } public Object getFieldValue(JRField jrf) throws JRException { Object retVal = null; if(currentObject == null) { return null; } try { retVal = PropertyUtils.getProperty(currentObject, jrf.getName()); } catch (Exception ex) { Logger.getLogger(CriteriaReportSource.class.getName()).log(Level.SEVERE, null, ex); } return retVal; } }

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Do you have health checks in your web app or web site?

- by Pekka

I have built PHP based "health check" scripts for several projects, but they were always custom-made for the occasion and not written for abstraction as an independent product. I would like to know whether such a solution exists. What I meam by "health check" is a protected web page that functions much like a suite of unit tests, but on a more operational level, showing red/yellow/green statuses for things like Are the cache directories writable? Is the PHP version correct, are required extensions installed? Is the configuration file protected from writing? Is the database server reachable? Do the key tables exist in the database? Is there enough disk space available? Is the site's front page reachable and renders fully ( = no PHP errors)? Do the project's libraries' MD5 checksums match the original ones? Do you do this - or parts of it - in your applications and web sites? Are there any standardized tools for this that bring along all the functionality to perform the tests (ideally as plugins), and just need to be configured accordingly? Is there a way to set this up using one of the Unit Testing frameworks available for PHP (preferably PHPUnit)? If so, do you know any resources / tutorials outlining how?

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Set a callback function to a new window in javascript

- by SztupY

Is there an easy way to set a "callback" function to a new window that is opened in javascript? I'd like to run a function of the parent from the new window, but I want the parent to be able to set the name of this particular function (so it shouldn't be hardcoded in the new windows page). For example in the parent I have: function DoSomething { alert('Something'); } ... <input type="button" onClick="OpenNewWindow(linktonewwindow,DoSomething);" /> And in the child window I want to: <input type="button" onClick="RunCallbackFunction();" /> The question is how to create this OpenNewWindow and RunCallbackFunction functions. I though about sending the function's name as a query parameter to the new window (where the server side script generates the appropriate function calls in the generated child's HTML), which works, but I was thinking whether there is another, or better way to accomplish this, maybe something that doesn't even require server side tinkering. Pure javascript, server side solutions and jQuery (or other frameworks) are all welcomed.

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How to create a generic C free function .

- by nomemory

I have some C structures related to a 'list' data structure. They look like this. struct nmlist_element_s { void *data; struct nmlist_element_s *next; }; typedef struct nmlist_element_s nmlist_element; struct nmlist_s { void (*destructor)(void *data); int (*cmp)(const void *e1, const void *e2); unsigned int size; nmlist_element *head; nmlist_element *tail; }; typedef struct nmlist_s nmlist; This way I can have different data types being hold in "nmlist_element-data" . The "constructor" (in terms of OOP) has the following signature: nmlist *nmlist_alloc(void (*destructor)(void *data)); Where "destructor" is specific function that de-allocated "data" (being hold by the nmlist_element). If I want to have a list containing integers as data, my "destructor" would like this: void int_destructor(void *data) { free((int*)data); } Still i find it rather "unfriendly" for me to write a destructor functions for every simple primitive data type. So is there a trick to write something like this ? (for primitives): void "x"_destructor(void *data, "x") { free(("x" *)data); } PS: I am not a macro fan myself, and in my short experience regarding C, i don't use them, unless necessary.

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Works in Firefox & Opera, but not IE 8

- by Ai Pragma

1) This issue involves just one html webpage, lets call it "ajax.html".2) I have AJAX functions in this webpage that work in both Firefox and IE8.3) I now attempt generating just the option values of a dropdown list of dates using my ajax functions, and it works in Firefox & Opera, but not IE8.4) The surrounding html code for the dropdown looks like this:<select name="entry_7_single" id="entry_7" onChange="Ajax_PhpResultsWithVar('./secure/db/SummaryCls.php','entry_8','dateval',this.value)"></select>The onchange call refers to an ajax function that successfully(both Firefox & IE8) populates a textarea(entry_8) with a description of an event associated with the date selected in this dropdown. 5) An onload call initiates the ajax function to generate the dropdown list values:<body class="ss-base-body" onLoad="OnLoadWebPage()">6) The js script that calls the ajax function is as follows:function OnLoadWebPage(){ Ajax_PhpResults('./secure/db/GenDateListCls.php','entry_7');}7) Since it works in Firefox, but not IE8, I throw the output of the ajax function into a Firefox large textbox and I get the following:<option selected value="8 JUN 2010">8 JUN 2010</option> <option value="9 JUN 2010">9 JUN 2010</option> <option value="10 JUN 2010">10 JUN 2010</option> <option value="11 JUN 2010">11 JUN 2010</option> 8 ) There are over a hundred generated but you get the gist of what the ajax function generates. Next I will list the PHP function that outputs the above dropdown values://///////////////////////////////////////////////////////////////////////////////////////////////////////<?phpinclude_once 'SPSQLite.class.php';include_once 'misc_funcs.php';class GenDateListCls { var $dbName; var $sqlite; function GenDateListCls() { $this->dbName = 'accrsc.db'; $this->ConstructEventDates(); } function ConstructEventDates() { $this->sqlite = new SPSQLite($this->dbName); $todayarr = getdate(); $today = $todayarr[mday] . " " . substr($todayarr[month],0,3) . " " . $todayarr[year]; $ICalDate = ChangeToICalDate($today); $dateQuery = "SELECT dtstart from events where substr(dtstart,1,8) >= '" . $ICalDate . "';"; $this->sqlite->query($dateQuery); $datesResult = $this->sqlite->returnRows(); foreach (array_reverse($datesResult) as $indx => $row) { $normDate = NormalizeICalDate(substr($row[dtstart],0,8)); if ($indx==0) { ?> <option selected value=<?php echo('"' . $normDate . '"'); ?>><?php echo $normDate; ?></option><?php } else {?> <option value=<?php echo('"' . $normDate . '"'); ?>><?php echo $normDate; ?></option><?php } } $this->sqlite->close(); }}$dateList = new GenDateListCls(); ?>/////////////////////////////////////////////////////////////////////////////////////////////////////////////<<< I appreciate any assistance on this matter. Aipragma >>> My Background: To let you all know, I am a complete newbie to PHP, Ajax, & javascript, and learning it all on my own, no classes. My background is in Linux, Windows, C++, Java, VB,VBA,MS XML, & some html.

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Flash Player scripting + IE8

- by Joel Alejandro

I've developed a small control bar for a Flash viewer generated by a third-party software. It has a First, Prev, Next & Last button, and a Zoom command. While Zoom works fine in all browsers, the navigation buttons seem to fail at Internet Explorer 8. I use at least two functions. This one locates the Flash object I want to manipulate: function getFlashMovieObject(movieName) { if (window.document[movieName]) { return window.document[movieName]; } if (navigator.appName.indexOf("Microsoft Internet")==-1) { if (document.embeds && document.embeds[movieName]) return document.embeds[movieName]; } else // if (navigator.appName.indexOf("Microsoft Internet")!=-1) { return document.getElementById(movieName); } } ...and any of these ones handles the frame navigation: var currentFrame = 0; function gotoFirst(id) { getFlashMovieObject(id + "Blueprints").Rewind(); currentFrame = 0; $("currentFrame").innerHTML = currentFrame + 1; $("frameTitle").innerHTML = frameTitles[id][currentFrame]; } function gotoPrev(id) { var movie = getFlashMovieObject(id + "Blueprints"); if (currentFrame 0) { currentFrame--; } movie.GotoFrame(currentFrame); $("currentFrame").innerHTML = currentFrame + 1; $("frameTitle").innerHTML = frameTitles[id][currentFrame]; } function gotoNext(id) { var movie = getFlashMovieObject(id + "Blueprints"); if (currentFrame < movie.TotalFrames() - 1) { currentFrame++; } movie.GotoFrame(currentFrame); $("currentFrame").innerHTML = currentFrame + 1; $("frameTitle").innerHTML = frameTitles[id][currentFrame]; } function gotoLast(id) { var movie = getFlashMovieObject(id + "Blueprints"); currentFrame = movie.TotalFrames() - 1; movie.GotoFrame(currentFrame); $("currentFrame").innerHTML = currentFrame + 1; $("frameTitle").innerHTML = frameTitles[id][currentFrame]; } Btw, that $ is MooTools, not jQuery. Anyway, IE dies on the movie.TotalFrames() call. What can I do to solve this? Keep in mind I need this to be done via JavaScript, as I cannot edit the SWF.

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How do I do MongoDB console-style queries in PHP?

- by Zoe Boles

I'm trying to get a MongoDB query from the javascript console into my PHP app. What I'm trying to avoid is having to translate the query into the PHP "native driver"'s format... I don't want to hand build arrays and hand-chain functions any more than I want to manually build an array of MySQL's internal query structure just to get data. I already have a string producing the exact content I want in the Mongo console: db.intake.find({"processed": {"$exists": "false"}}).sort({"insert_date": "1"}).limit(10); The question is, is there a way for me to hand this string, as is, to MongoDB and have it return a cursor with the dataset I request? Right now I'm at the "write your own parser because it's not valid json to kinda turn a subset of valid Mongo queries into the format the PHP native driver wants" state, which isn't very fun. I don't want an ORM or a massive wrapper library; I just want to give a function my query string as it exists in the console and get an Iterator back that I can work with. I know there are a couple of PHP-based Mongo manager applications that apparently take console-style queries and handle them, but initial browsing through their code, I'm not sure how they handle the translation. I absolutely love working with mongo in the console, but I'm rapidly starting to loathe the thought of converting every query into the format the native writer wants...

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Getting element position in IE versus other browsers

- by Channel72

We all know IE6 is difficult. But there seems to be disparate behavior in positioning in later versions of IE as well, when compared with Firefox or other browsers. I have a simple pair of javascript functions which finds the position of an element, and then displays another element in relation to the first element. The idea is to get the second element, which is somewhat larger, to appear in front of the first element when the mouse hovers over it. It works fine, except on all versions of Internet Explorer, the position of the second element appears different than in Firefox. The code to get the position of an element is: function getPosition(e) { var left = 0; var top = 0; while (e.offsetParent) { left += e.offsetLeft; top += e.offsetTop; e = e.offsetParent; } left += e.offsetLeft; top += e.offsetTop; return {x:left, y:top}; } And the actual rollover display code is: var pos = getPosition(elem1); elem2.style.top = pos.y - 8; elem2.style.left = pos.x - 6; In Firefox, elem2 appears directly over elem1, as I want it to. But in IE7 or IE8 it appears way off. What is the reason this occurs, and is there a way to fix it?

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php OOP function declarations

- by kris

I'm a big fan of OOP in php, but i feel like defining class methods gets disorganized so fast. I have a pretty good background in OOP in C++, and i am pretty comfortable with how it is handled there, and am curious if there are ways to do it similarly in php. To be more specific, here is what i mean. I like how in C++ you can define a class header (myclass.h) and then define the actual details of the functions in the implementation file (myclass.cc). Ive found that this can easily be replicated using interfaces in php, but i havent found a good solution for the following: I like to organize my code in C++ in different files based on how they are accessed, so for example, public methods that can be called outside of the class would be in 1 place, and private methods would be organized somewhere else - this is personal preference. Ive tried to define class methods in php like: private function MyPHPClass::myFunction(){ } when the definition isnt directly inside the class block( { } ), but i havent had any success doing this. Ive been through all of the pages on php.net, but couldnt find anything like this. Im assuming that there is no support for something like this, but thought i would ask anyway. thanks

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Joining Tables Based on Foreign Keys

- by maestrojed

I have a table that has a lot of fields that are foreign keys referencing a related table. I am writing a script in PHP that will do the db queries. When I query this table for its data I need to know the values associated with these keys not the key. How do most people go about this? A 101 way to do this would be to query this table for its data including the foreign keys and then query the related tables to get each key's value. This could be a lot of queries (~10). Question 1: I think I could write 1 query with a bunch of joins. Would that be better? This approach also requires the querying script to know which table fields are foreign keys. Since I have many tables like this but all with different fields, this means writing nice generic functions is hard. MySQL InnoDB tables allow for foreign constraints. I know the database has these set up correctly. Question 2: What about the idea of querying the table and identifying what the constraints are and then matching them up using whatever process I decide on from Question 1. I like this idea but never see it being used in code. Makes me think its not a good idea for some reason. I would use something like SHOW CREATE TABLE tbl_name; to find what constraints/relationships exist for that table. Thank you for any suggestions or advice.

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__toString magic and type coercion

- by TomcatExodus

I've created a Template class for managing views and their associated data. It implements Iterator and ArrayAccess, and permits "sub-templates" for easy usage like so: <p><?php echo $template['foo']; ?></p> <?php foreach($template->post as $post): ?> <p><?php echo $post['bar']; ?></p> <?php endforeach; ?> Anyways, rather than using inline core functions, such as hash() or date(), I figured it would be useful to create a class called TemplateData, which would act as a wrapper for any data stored in the templates. This way, I can add a list of common methods for formatting, for example: echo $template['foo']->asCase('upper'); echo $template['bar']->asDate('H:i:s'); //etc.. When a value is set via $template['foo'] = 'bar'; in the controllers, the value of 'bar' is stored in it's own TemplateData object. I've used the magic __toString() so when you echo a TemplateData object, it casts to (string) and dumps it's value. However, despite the mantra controllers and views should not modify data, whenever I do something like this: $template['foo'] = 1; echo $template['foo'] + 1; //exception It dies on a Object of class TemplateData could not be converted to int; Unless I recast $template['foo'] to a string: echo ((string) $template['foo']) + 1; //outputs 2 Sort of defeats the purpose having to jump through that hoop. Are there any workarounds for this sort of behavior that exist, or should I just take this as it is, an incidental prevention of data modification in views?

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Few Basic Questions in Overriding

- by Dahlia

I have few problems with my basic and would be thankful if someone can clear this. What does it mean when I say base *b = new derived; Why would one go for this? We very well separately can create objects for class base and class derived and then call the functions accordingly. I know that this base *b = new derived; is called as Object Slicing but why and when would one go for this? I know why it is not advisable to convert the base class object to derived class object (because base class is not aware of the derived class members and methods). I even read in other StackOverflow threads that if this is gonna be the case then we have to change/re-visit our design. I understand all that, however, I am just curious, Is there any way to do this? class base { public: void f(){cout << "In Base";} }; class derived:public base { public: void f(){cout << "In Derived";} }; int _tmain(int argc, _TCHAR* argv[]) { base b1, b2; derived d1, d2; b2 = d1; d2 = reinterpret_cast<derived*>(b1); //gives error C2440 b1.f(); // Prints In Base d1.f(); // Prints In Derived b2.f(); // Prints In Base d1.base::f(); //Prints In Base d2.f(); getch(); return 0; } In case of my above example, is there any way I could call the base class f() using derived class object? I used d1.base()::f() I just want to know if there any way without using scope resolution operator? Thanks a lot for your time in helping me out!

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FF extension: saving a value in preferences and retrieving in the js file

- by encryptor

I am making an extension which should take a link as the user input only once. Then the entire extension keeps using that link on various functions in the JS file. When the user changes it, the value accessed by the js file also changes accordingly. I am using the following but it does not work for me var pref_manager = Components.classes["@mozilla.org/preferencesservice;1"].getService(Components.interfaces.nsIPrefService) function setInstance(){ if (pref_manager.prefHasUserValue("myvar")) { instance = pref_manager.getString("myvar"); alert(instance); } if(instance == null){ instance = prompt("Please enter webcenter host and port"); // Setting the value pref_manager.setString("myvar", instance); } } instance is the global variable in which i take the user input. The alert (instance) does not show up, which means there is some problem by the way i am saving the pref or extracting it. Can someone please help me with this. I have never worked with preferences before. so even if there are minor problems i might not be able to figure out.

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Scanner error that I can't figure out: NoSuchElementException

- by iaacp

It's crashing on the third line inside the do-while loop, and doesn't wait for my input: input = kb.nextInt(); Stack trace: Exception in thread "main" java.util.NoSuchElementException at java.util.Scanner.throwFor(Unknown Source) at java.util.Scanner.next(Unknown Source) at java.util.Scanner.nextInt(Unknown Source) at java.util.Scanner.nextInt(Unknown Source) at main.MainDriver.main(MainDriver.java:50) Relevant code: do { displayFullMenu(); System.out.print("Selection: "); input = kb.nextInt(); switch (input) { //Create new survey case 1: currentSurvey = new Survey(); break; //Display current survey case 2: currentSurvey.display(); break; //Save current survey case 3: saveSurvey(currentSurvey); break; //Load a survey case 4: currentSurvey = loadSurvey(); break; //Modify a survey case 5: currentSurvey.modify(); break; /*******************Test Functions*******************/ //Create new test case 6: currentSurvey = new Test(); break; //Display current test case 7: currentSurvey.display(); break; //Save current test case 8: saveSurvey(currentSurvey); break; //Load a test case 9: currentSurvey = loadTest(); break; //Modify a test case 10: currentSurvey.modify(); default: System.out.println("Invalid choice. Please make a valid choice: "); input = kb.nextInt(); System.out.println(); } } while (input != 99); kb.close(); It crashes after I choose option 9. It saves the file correctly, then goes back to the top of the loop, and crashes at the previously mentioned line. I want it to ask for more input. What gives?

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Finding users whose birtday is today with JPA

- by Jeduan Cornejo

Hi, I have a table with users and are trying to get a list with the people who have birthday today so the app can send an email. The User is defined as @Entity public class User { @Size(max = 30) @NotNull private String name; [...] @Temporal(TemporalType.DATE) @DateTimeFormat(style = "S-") protected Date birthday; } and I've got a method which returns the people which were born today like so @SuppressWarnings("unchecked") public static List<User> findUsersWithBirthday() { List<User> users = entityManager().createQuery("select u from User u where u.birthday = :date") .setParameter("date", new Date(), TemporalType.DATE) .getResultList(); return users; } This is fine and all for finding people which were born today, however tha's not really that useful, so I've been struggling for a way to find all the users that were born today, independent of the year. Using MySQL there's functions I can use like select month(curdate()) as month, dayofmonth(curdate()) as day However I've been struggling to find a JPA equivalent to that. I'm using Spring 3.0.1 and Hibernate 3.3.2

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Failure remediation strategy for File I/O

- by Brett

I'm doing buffered IO into a file, both read and write. I'm using fopen(), fseeko(), standard ANSI C file I/O functions. In all cases, I'm writing to a standard local file on a disk. How often do these file I/O operations fail, and what should the strategy be for failures? I'm not exactly looking for stats, but I'm looking for a general purpose statement on how far I should go to handle error conditions. For instance, I think everyone recognizes that malloc() could and probably will fail someday on some user's machine and the developer should check for a NULL being returned, but there is no great remediation strategy since it probably means the system is out of memory. At least, this seems to be the approach taken with malloc() on desktop systems, embedded systems are different. Likewise, is it worth reattempting a file I/O operation, or should I just consider a failure to be basically unrecoverable, etc. I would appreciate some code samples demonstrating proper usage, or a library guide reference that indicates how this is to be handled. Any other data is, of course, welcome.

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BCrypt says long, similar passwords are equivalent - problem with me, the gem, or the field of crypt

- by PreciousBodilyFluids

I've been experimenting with BCrypt, and found the following. If it matters, I'm running ruby 1.9.2dev (2010-04-30 trunk 27557) [i686-linux] require 'bcrypt' # bcrypt-ruby gem, version 2.1.2 @long_string_1 = 'f287ed6548e91475d06688b481ae8612fa060b2d402fdde8f79b7d0181d6a27d8feede46b833ecd9633b10824259ebac13b077efb7c24563fce0000670834215' @long_string_2 = 'f6ebeea9b99bcae4340670360674482773a12fd5ef5e94c7db0a42800813d2587063b70660294736fded10217d80ce7d3b27c568a1237e2ca1fecbf40be5eab8' def salted(string) @long_string_1 + string + @long_string_2 end encrypted_password = BCrypt::Password.create(salted('password'), :cost => 10) puts encrypted_password #=> $2a$10$kNMF/ku6VEAfLFEZKJ.ZC.zcMYUzvOQ6Dzi6ZX1UIVPUh5zr53yEu password = BCrypt::Password.new(encrypted_password) puts password.is_password?(salted('password')) #=> true puts password.is_password?(salted('passward')) #=> true puts password.is_password?(salted('75747373')) #=> true puts password.is_password?(salted('passwor')) #=> false At first I thought that once the passwords got to a certain length, the dissimilarities would just be lost in all the hashing, and only if they were very dissimilar (i.e. a different length) would they be recognized as different. That didn't seem very plausible to me, from what I know of hash functions, but I didn't see a better explanation. Then, I tried shortening each of the long_strings to see where BCrypt would start being able to tell them apart, and I found that if I shortened each of the long strings to 100 characters or so, the final attempt ('passwor') would start returning true as well. So now I don't know what to think. What's the explanation for this?

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C++: parsing with simple regular expression or shoud I use sscanf?

- by Helltone

I need to parse a string like func1(arg1, arg2); func2(arg3, arg4);. It's not a very complex parsing problem, so I would prefer to avoid resorting to flex/bison or similar utilities. My first approch was to try to use POSIX C regcomp/regexec or Boost implementation of C++ std::regex. I wrote the following regular expression, which does not work (I'll explain why further on). "^" "[ ;\t\n]*" "(" // (1) identifier "[a-zA-Z_][a-zA-Z0-9_]*" ")" "[ \t\n]*" "(" // (2) non-marking "\[" "(" // (3) non-marking "[ \t]*" "(" // (4..n-1) argument "[a-zA-Z0-9_]+" ")" "[ \t\n]*" "," ")*" "[ \t\n]*" "(" // (n) last argument "[a-zA-Z0-9_]+" ")" "]" ")?" "[ \t\n]*" ";" Note that the group 1 captures the identifier and groups 4..n-1 are intended to capture arguments except the last, which is captured by group n. When I apply this regex to, say func(arg1, arg2, arg3) the result I get is an array {func, arg2, arg3}. This is wrong because arg1 is not in it! The problem is that in the standard regex libraries, submarkings only capture the last match. In other words, if you have for instance the regex "((a*|b*))*" applied on "babb", the results of the inner match will be bb and all previous captures will have been forgotten. Another thing that annoys me here is that in case of error there is no way to know which character was not recognized as these functions provide very little information about the state of the parser when the input is rejected. So I don't know if I'm missing something here... In this case should I use sscanf or similar instead? Note that I prefer to use C/C++ standard libraries (and maybe boost).

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Designing a class in such a way that it doesn't become a "God object"

- by devoured elysium

I'm designing an application that will allow me to draw some functions on a graphic. Each function will be drawn from a set of points that I will pass to this graphic class. There are different kinds of points, all inheriting from a MyPoint class. For some kind of points it will be just printing them on the screen as they are, others can be ignored, others added, so there is some kind of logic associated to them that can get complex. How to actually draw the graphic is not the main issue here. What bothers me is how to make the code logic such that this GraphicMaker class doesn't become the so called God-Object. It would be easy to make something like this: class GraphicMaker { ArrayList<Point> points = new ArrayList<Point>(); public void AddPoint(Point point) { points.add(point); } public void DoDrawing() { foreach (Point point in points) { if (point is PointA) { //some logic here else if (point is PointXYZ) { //...etc } } } } How would you do something like this? I have a feeling the correct way would be to put the drawing logic on each Point object (so each child class from Point would know how to draw itself) but two problems arise: There will be kinds of points that need to know all the other points that exist in the GraphicObject class to know how to draw themselves. I can make a lot of the methods/properties from the Graphic class public, so that all the points have a reference to the Graphic class and can make all their logic as they want, but isn't that a big price to pay for not wanting to have a God class?

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Eclipse PDT "tips" ?

- by Pascal MARTIN

Hi ! (Yes, this is a quite opened and general and subjective question -- it's by design, cause I want tips you think are great !) I'm using Eclipse PDT 2.1 to work in PHP, either for small and/or big projects -- I've been doing so for quite some times, now, actually (since before 1.0 stable, if I remember well)... I was wondering if any of you did know "tips" to be more efficient. Let met explain more in details : I know about things like plugins like Aptana (better editor for JS/CSS), Subversive (for SVN access), RSE, Filesync, integrating Xdebug's debugger, ... What I mean by "tips" is more some little things you discovered one day and since use all the time -- and allow you to be more efficient in your PHP projects. Some examples of "tips" that come to my mind, and that already know and use : ctrl+space to open the list of suggestions for functions / variables names ctrl+shift+R (navigate > open resource) to open a popup which show only files which names contain what you type ; ie, quick opening of files this one might be the perfect example : I know this one is not often known by coworkers and they find it as useful as I do ; so, I guess there might be lots of other things like this one I don't know myself ^^ ctrl+M to switch to full-screen view for the editor (instead of double-click on tabs bar) shift+F2 while on a function name, to open it's page if the PHP manual in a browser Attention Mac Users use Command instead Control. I guess you get the point ; but I'm really open to any suggestion (be it eclipse-related in general, of more PHP/PDT-specific) that can help be be more efficient :-) Anyway, thanks in advance for your help !

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Setting the default stack size on Linux globally for the program

- by wowus

So I've noticed that the default stack size for threads on linux is 8MB (if I'm wrong, PLEASE correct me), and, incidentally, 1MB on Windows. This is quite bad for my application, as on a 4-core processor that means 64 MB is space is used JUST for threads! The worst part is, I'm never using more than 100kb of stack per thread (I abuse the heap a LOT ;)). My solution right now is to limit the stack size of threads. However, I have no idea how to do this portably. Just for context, I'm using Boost.Thread for my threading needs. I'm okay with a little bit of #ifdef hell, but I'd like to know how to do it easily first. Basically, I want something like this (where windows_* is linked on windows builds, and posix_* is linked under linux builds) // windows_stack_limiter.c int limit_stack_size() { // Windows impl. return 0; } // posix_stack_limiter.c int limit_stack_size() { // Linux impl. return 0; } // stack_limiter.cpp int limit_stack_size(); static volatile int placeholder = limit_stack_size(); How do I flesh out those functions? Or, alternatively, am I just doing this entirely wrong? Remember I have no control over the actual thread creation (no new params to CreateThread on Windows), as I'm using Boost.Thread.

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