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  • Mac OS X and static boost libs -> std::string fail

    - by Ionic
    Hi all, I'm experiencing some very weird problems with static boost libraries under Mac OS X 10.6.6. The error message is main(78485) malloc: *** error for object 0x1000e0b20: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug [1] 78485 abort (core dumped) and a tiny bit of example code which will trigger this problem: #define BOOST_FILESYSTEM_VERSION 3 #include <boost/filesystem.hpp> #include <iostream> int main (int argc, char **argv) { std::cout << boost::filesystem::current_path ().string () << '\n'; } This problem always occurs when linking the static boost libraries into the binary. Linking dynamically will work fine, though. I've seen various reports for quite a similar OS X bug with GCC 4.2 and the _GLIBCXX_DEBUG macro set, but this one seems even more generic, as I'm neither using XCode, nor setting the macro (even undefining it does not help. I tried it just to make sure it's really not related to this problem.) Does anybody have any pointers to why this is happening or even maybe a solution (rather than using the dynamic library workaround)? Best regards, Mihai

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  • Conditionally overriding a system method via categories in Objective-C?

    - by adib
    Hi Is there a way to provide a method implementation (that bears the exact same name of a method defined by the framework) only when the method isn't already defined in the system? For example method [NSSomeClass someMethod:] exists only in Mac OS X 10.6 and if my app runs in 10.5, I will provide that method's definition in a category. But when the app runs in 10.6, I want the OS-provided method to run. Background: I'm creating an app targeted for both 10.5 and 10.6. The problem is that I recently realized that method +[NSSortDescriptor sortDescriptorWithKey:ascending:] only exists in 10.6 and my code is already littered by that method call. I could provide a default implementation for it (since this time it's not too difficult to implement it myself), but I want the "native" one to be called whenever my app runs on 10.6. Furthermore if I encounter similar problems in the future (with more difficult-to-implement-myself methods), I might not be able to get away with providing a one-liner replacement. This question vaguely similar to Override a method via ObjC Category and call the default implementation? but the difference is that I want to provide implementations only when the system doesn't already has one. Thanks.

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  • Passing Binary Data to a Stored Procedure in SQL Server 2008

    - by Joe Majewski
    I'm trying to figure out a way to store files in a database. I know it's recommended to store files on the file system rather than the database, but the job I'm working on would highly prefer using the database to store these images (files). There are also some constraints. I'm not an admin user, and I have to make stored procedures to execute all the commands. This hasn't been of much difficulty so far, but I cannot for the life of me establish a way to store a file (image) in the database. When I try to use the BULK command, I get an error saying "You do not have permission to use the bulk load statement." The bulk utility seemed like the easy way to upload files to the database, but without permissions I have to figure a work-a-round. I decided to use an HTML form with a file upload input type and handle it with PHP. The PHP calls the stored procedure and passes in the contents of the file. The problem is that now it's saying that the max length of a parameter can only be 128 characters. Now I'm completely stuck. I don't have permissions to use the bulk command and it appears that the max length of a parameter that I can pass to the SP is 128 characters. I expected to run into problems because binary characters and ascii characters don't mix well together, but I'm at a dead end... Thanks

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  • Minimal assembler program for CP/M 3.1 (z80)

    - by Andrew J. Brehm
    I seem to be losing the battle against my stupidity. This site explains the system calls under various versions of CP/M. However, when I try to use call 2 (C_WRITE, console output), nothing much happens. I have the following code. ORG 100h LD E,'a' LD C,2 CALL 5 CALL 0 I recite this here from memory. If there are typos, rest assured they were not in the original since the file did compile and I had a COM file to start. I am thinking the lines mean the following: Make sure this gets loaded at address 100h (0h to FFh being the zero page). Load ASCII 'a' into E register for system call 2. Load integer 2 into C register for system call 2. Make system call (JMP to system call is at address 5 in zero page). End program (Exit command is at address 0 in zero page). The program starts and exits with no problems. If I remove the last command, it hangs the computer (which I guess is also expected and shows that CALL 0 works). However, it does not print the ASCII character. (But it does print an extra new line, but the system might have done that.) How can I get my CP/M program to do what the system call is supposed to do? What am I doing wrong?

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  • Stop Child Elements from Inheriting Parent Style, Broken Tabs Javascript

    - by WillingLearner
    I am using the flowplayer jquery tabs plugin: http://flowplayer.org/tools/tabs/index.html Im having mucho difficulty when placing my child elements inside the panes divs, and stopping them from inheriting the style of the container pane div. Its breaking my layout to pieces and i need to know how to override the style and just keep the container panes div only to itself. Also, im having a devil of a time trying to call 2 different sets of tabs and panes. Im not getting the classes and IDs right, the javascript, or something along those lines. How would i set this up so i can call (tabs A / panes A) and then (tabs B / panes B), css wise, and javascript wise? My current javascript is: <!-- This JavaScript snippet activates the tabs --> <script> // perform JavaScript after the document is scriptable. $(function() { // setup ul.tabs to work as tabs for each div directly under div.panes $("ul.tabs").tabs("div.panes1 > div"); //$("ul.tabs.myprofile").tabs("div.panes > div"); }); </script> This only works for 1 set of tabs and panes on a page. Dosent help me much if i want to call 2 totally different sets. Ive gone over the documentation many times but im still not getting it. Please help me find a solution to BOTH of my problems. Thanks.

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  • Project Euler Problem #11

    - by SoulBeaver
    Source: http://projecteuler.net/index.php?section=problems&id=11 Quick overview: Take a 20x20 grid of numbers and compute the largest product of 4 pairs of numbers in either horizontal, vertical, or diagonal. My current approach is to divide the 20x20 grid up into single rows and single columns and go from there with a much more manageable grid. The code I'm using to divide the rows into rows is void fillRows ( string::const_iterator& fieldIter, list<int>& rowElements, vector<list<int>>& rows ) { int count(0); for( ; fieldIter < field.end(); ++fieldIter ) { if(isdigit(field[*fieldIter])) { rowElements.push_back(toInt(field[*fieldIter])); ++count; } if(count == 40) { rows.push_back(rowElements); count = 0; rowElements.clear(); } } } Short explanation: I have the field set as static const std::string field and I am filling a vector with lists of rows. Why a list? Because the queue doesn't have a clear function. Also practice using STL container lists and not ones I write myself. However, this thing isn't working. Oftentimes I see it omitting a character( function toInt parses the const char as int ) and I end up with 18 rows, two rows short of the 20x20 grid. The length of the rows seem good. Rows: 18 RowElements[0]: 40 (instead of pairs I saved each number individually. Will fix that later) What am I doing wrong?

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  • How to get resultset with stored procedure calls over two linked servers?

    - by räph
    I have problems filling a temporary table with the resultset from a procedure call on a linked server, in which again a procedure on another server is called. I have a Stored Procedure sproc1 with the following code, which calls another procedure sproc2 on a linked server. SET @sqlCommand = 'INSERT INTO #tblTemp ( ModuleID, ParamID) ' + '( SELECT * FROM OPENQUERY(' + @targetServer + ', ' + '''SET FMTONLY OFF; EXEC ' + @targetDB + '.usr.sproc2 ' + @param + ''' ) )' exec ( @sqlCommand ) Now in the called sproc2 I again call a third procedure sproc3 on another linked server, which returns my resultset. SET @sqlCommand = 'EXEC ' + @targetServer +'.database.usr.sproc3 ' + @param exec ( @sqlCommand ) The whole thing doen't work, as I get an SQL error 7391 The operation could not be performed because OLE DB provider "%ls" for linked server "%ls" was unable to begin a distributed transaction. I already checked the hints at this microsoft article, but without success. But maybe, I can change the code in sproc1. Would there be some alternative to the temp table and the open query? Just calling stored procedures from server A to B to C and returning the resultset is working (I do this often in the application). But this special case with the temp table and openquery doesn't work! Or is it just not possible what I am trying to do? The microsft article states: Check the object you refer on the destination server. If it is a view or a stored procedure, or causes an execution of a trigger, check whether it implicitly references another server. If so, the third server is the source of the problem. Run the query directly on the third server. If you cannot run the query directly on the third server, the problem is not actually with the linked server query. Resolve the underlying problem first. Is this my case? PS: I can't avoid the architecture with the three servers.

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  • Designing a general database interface in PHP

    - by lamas
    I'm creating a small framework for my web projects in PHP so I don't have to do the basic work over and over again for every new website. It is not my goal to create a second CakePHP or Codeigniter and I'm also not planning to build my websites with any of the available frameworks as I prefer to use things I've created myself in general. I have no problems in designing that framework when it comes to parts like the core structure, request handling, and so on but I'm getting stuck with designing the database interface for my modules. I've already thought about using the MVC pattern but thought that it would be a bit of a overkill. So the exact problem I'm facing is how my frameworks modules (viewCustomers could be a module, for example) should interact with the database. Is it a good idea to write SQL directly in PHP (mysql_query( 'SELECT firstname, lastname(.....))? How could I abstract a query like SELECT firstname, lastname FROM customers WHERE id=X Would MySQL helper functions like $this->db->get( array('firstname', 'lastname'), array('id'=>X) ) be a good idea? I suppose not because they actually make everything more complicated by requiring arrays to be created and passed. Is the Model pattern from MVC my only real option?

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  • Would this method work to scale out SQL queries?

    - by David
    I have a database containing a single huge table. At the moment a query can take anything from 10 to 20 minutes and I need that to go down to 10 seconds. I have spent months trying different products like GridSQL. GridSQL works fine, but is using its own parser which does not have all the needed features. I have also optimized my database in various ways without getting the speedup I need. I have a theory on how one could scale out queries, meaning that I utilize several nodes to run a single query in parallel. The idea is to take an incoming SQL query and simply run it exactly like it is on all the nodes. When the results are returned to a coordinator node, the same query is run on the union of the resultsets. I realize that an aggregate function like average need to be rewritten into a count and sum to the nodes and that the coordinator divides the sum of the sums with the sum of the counts to get the average. What kinds of problems could not easily be solved using this model. I believe one issue would be the count distinct function. Edit: I am getting so many nice suggestions, but none have addressed the method.

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  • nhibernate fluent repository pattern insert problem

    - by voam
    I am trying to use Fluent NHibernate and the repository pattern. I would like my business layer to not be knowledgeable of the data persistence layer. Ideally I would pass in an initialized domain object to the insert method of the repository and all would be well. Where I run into problems is if the object being passed in has a child object. For example say I want to insert an a new order for a customer, and the customer is a property of the order object. I would like to do something like this: Customer c = new Customer; c.CustomerId = 1; Order o = new Order; o.Customer = c; repository.InsertOrder(o); The problem is that using NHiberate the CustomerId field is only privately settable so I can not set it directly like this. so what I have ended up doing is have my repository have an interface of Order InsertOrder(int customerId) where all the foreign keys get passed in as parameters. Somehow this just doesn't seem right. The other approach was to use the NHibernate session variable to load a customer object in my business model and then have the order passed in to the repository but this defeats my persistence ignorance ideal. Should I throw this persistence ignorance out the window or am I missing something here? Thanks

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  • Web-app currency input/manipulation/calculation with javascript .. there has got to be a better (fra

    - by dreftymac
    BACKGROUND: I am of the "user-input-lockdown" school of thought. Whenever possible, I try to mistrust and sanitize user input, both client side and server side; and I try to take multiple opportunities to restrict possible inputs to a known subset of possibilities, usually this means providing a lot of checkboxes and select lists. (This is from the usability side of things, I know security-wise that malicious users can easily bypass fixed user input GUI controls). PROBLEM: Anyway, the problem always arises with non-fixed input of currency. Whenever I have to accept a freely-specified dollar amount as user input, I always have to confront these problems/annoyances and it is always painful: 1) Make sure to give the user two input boxes for each currency_datapoint, one for the whole_dollar_part and another for the fractional_pennies_part 2) Whenever the user changes a currency_datapoint, provide keystroke-by-keystroke GUI feedback to let them know whether the currency_datapoint is well-formed, with context-appropriate validation rules (e.g., no negatives?, nonzero only?, numeric only!, no non-numeric punctuation! no symbols!) 3) For display purposes, every user-provided currency_datapoint should be translated to human-readable currency formatting (dollar sign, period, commas provided by the app, where appropriate) 4) For calculation purposes, every user-provided currency_datapoint has to be converted to integer (all pennies, to avoid floating point errors) and summed into a grand total with zero or more subtotals. 5) Every user-provided currency_datapoint should be displayed or displayable in a nice "tabular" format, which auto-updates as the user enters each currency_datapoint, including a baloon that warns when one or more currency_datapoints is not well-formed. I seem to be re-inventing this wheel every time I have to work with currency in Javascript on the client side (server side is a bit more flexible since most programming languages have higher-level currency formatting logic). QUESTION: Has anyone out there solved the problem of dealing with the above issues, client side, in a way that is server-side-technology-stack agnostic, (preferrably plain javascript or jquery)? This is getting old, there has to be a better way.

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  • ASP.NET MVC: Returning a view with querystring intact

    - by ajbeaven
    I'm creating a messaging web app in ASP.NET and are having some problems when displaying an error message to the user if they go to send a message and there is something wrong. A user can look through profiles of people and then click, 'send a message'. The following action is called (url is /message/create?to=username) and shows them a page where they can enter their message and send it: public ActionResult Create(string to) { ViewData["recipientUsername"] = to; return View(); } On the page that is displayed, the username is entered in to a hidden input field. When the user clicks 'send': [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(FormCollection collection, string message) { try { //do message stuff that errors out } catch { ModelState.AddModelErrors(message.GetRuleViolations()); //adding errors to modelstate } return View(); } So now the error message is displayed to the user fine, however the url is changed in that it no longer has the querystring (/message/create). Again, this would be fine except that when the user clicks the refresh button, the page errors out as the Create action no longer has the 'to' parameter. So I'm guessing that I need to maintain my querystring somehow. Is there any way to do this or do I need to use a different method altogether?

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  • Linux: modpost does not build anything

    - by waffleman
    I am having problems getting any kernel modules to build on my machine. Whenever I build a module, modpost always says there are zero modules: MODPOST 0 modules To troubleshoot the problem, I wrote a test module (hello.c): #include <linux/module.h> /* Needed by all modules */ #include <linux/kernel.h> /* Needed for KERN_INFO */ #include <linux/init.h> /* Needed for the macros */ static int __init hello_start(void) { printk(KERN_INFO "Loading hello module...\n"); printk(KERN_INFO "Hello world\n"); return 0; } static void __exit hello_end(void) { printk(KERN_INFO "Goodbye Mr.\n"); } module_init(hello_start); module_exit(hello_end); Here is the Makefile for the module: obj-m = hello.o KVERSION = $(shell uname -r) all: make -C /lib/modules/$(KVERSION)/build M=$(shell pwd) modules clean: make -C /lib/modules/$(KVERSION)/build M=$(shell pwd) clean When I build it on my machine, I get the following output: make -C /lib/modules/2.6.32-27-generic/build M=/home/waffleman/tmp/mod-test modules make[1]: Entering directory `/usr/src/linux-headers-2.6.32-27-generic' CC [M] /home/waffleman/tmp/mod-test/hello.o Building modules, stage 2. MODPOST 0 modules make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-27-generic' When I make the module on another machine, it is successful: make -C /lib/modules/2.6.24-27-generic/build M=/home/somedude/tmp/mod-test modules make[1]: Entering directory `/usr/src/linux-headers-2.6.24-27-generic' CC [M] /home/somedude/tmp/mod-test/hello.o Building modules, stage 2. MODPOST 1 modules CC /home/somedude/tmp/mod-test/hello.mod.o LD [M] /home/somedude/tmp/mod-test/hello.ko make[1]: Leaving directory `/usr/src/linux-headers-2.6.24-27-generic' I looked for any relevant documentation about modpost, but found little. Anyone know how modpost decides what to build? Is there an environment that I am possibly missing? BTW here is what I am running: uname -a Linux waffleman-desktop 2.6.32-27-generic #49-Ubuntu SMP Wed Dec 1 23:52:12 UTC 2010 i686 GNU/Linux

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  • Image drawing library for Haskell?

    - by absz
    I'm working on a Haskell program for playing spatial games: I have a graph of a bunch of "individuals" playing the Prisoner's Dilemma, but only with their immediate neighbors, and copying the strategies of the people who do best. I've reached a point where I need to draw an image of the world, and this is where I've hit problems. Two of the possible geometries are easy: if people have four or eight neighbors each, then I represent each one as a filled square (with color corresponding to strategy) and tile the plane with these. However, I also have a situation where people have six neighbors (hexagons) or three neighbors (triangles). My question, then, is: what's a good Haskell library for creating images and drawing shapes on them? I'd prefer that it create PNGs, but I'm not incredibly picky. I was originally using Graphics.GD, but it only exports bindings to functions for drawing points, lines, arcs, ellipses, and non-rotated rectangles, which is not sufficient for my purposes (unless I want to draw hexagons pixel by pixel*). I looked into using foreign import, but it's proving a bit of a hassle (partly because the polygon-drawing function requires an array of gdPoint structs), and given that my requirements may grow, it would be nice to use an in-Haskell solution and not have to muck about with the FFI (though if push comes to shove, I'm willing to do that). Any suggestions? * That is also an option, actually; any tips on how to do that would also be appreciated, though I think a library would be easier.

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  • How do tools like Hiphop for PHP deal with heterogenous arrays?

    - by Derek Thurn
    I think HipHop for PHP is an interesting tool. It essentially converts PHP code into C++ code. Cross compiling in this manner seems like a great idea, but I have to wonder, how do they overcome the fundamental differences between the two type systems? One specific example of my general question is heterogeneous data structures. Statically typed languages don't tend to let you put arbitrary types into an array or other container because they need to be able to figure out the types on the other end. If I have a PHP array like this: $mixedBag = array("cat", 42, 8.5, false); How can this be represented in C++ code? One option would be to use void pointers (or the superior version, boost::any), but then you need to cast when you take stuff back out of the array... and I'm not at all convinced that the type inferencer can always figure out what to cast to at the other end. A better option, perhaps, would be something more like a union (or boost::variant), but then you need to enumerate all possible types at compile time... maybe possible, but certainly messy since arrays can contain arbitrarily complex entities. Does anyone know how HipHop and similar tools which go from a dynamic typing discipline to a static discipline handle these types of problems?

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  • Are there solutions for streamlining the update of legacy code in multiple places?

    - by ccomet
    I'm working in some old code which was originally designed for handling two different kinds of files. I was recently tasked with adding a new kind of file to this code. Most of my problems were solved by filling out an extensive XML file with a new entry that handled everything from what lists were named to how the file is written in plural lower case. But this ended up being insufficient, as there were maybe 50 different places in 24 different code files where I had to update hardcoded switch-statements that only branched for the original two file types. Unfortunately there is no consistency in this; there are methods which operate half from the XML file, and half off of hardcode. Some of the files which look like they would operate off of the XML file don't, and some that I would expect that I'd need to update the hardcode don't need it. So the only way to find the majority of these is to run through testing the whole system when only part of it is operational, finding that one step to fix (when I'm lucky that error logging actually tells me what is going on), and then running the whole thing again. This wastes time testing the parts of the code which are already confirmed to work, time better spent testing the new parts I have to add on top of it all. It's a hassle and a half, and to my luck I can expect that I will have to add yet another new kind of file in the near future. Are there any solutions out there which can aid in this kind of endeavour? Something which I can input some parameters of current features, document what points in a whole code project actually need to be updated, and run something nice the next time I need to add a new feature to the code. It needn't even be fully automated, something that'll help me navigate straight to the specific points in everything and maybe even record what kind of parameters need to be loaded. Doubt it matters specifically, but the code is comprised of ASP.NET pages, some ASP.NET controls, hundreds of C# code files, and a handful of additional XML files. It's all currently in a couple big Visual Studio 2008 projects.

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  • JSON Twitter List in C#.net

    - by James
    Hi, My code is below. I am not able to extract the 'name' and 'query' lists from the JSON via a DataContracted Class (below) I have spent a long time trying to work this one out, and could really do with some help... My Json string: {"as_of":1266853488,"trends":{"2010-02-22 15:44:48":[{"name":"#nowplaying","query":"#nowplaying"},{"name":"#musicmonday","query":"#musicmonday"},{"name":"#WeGoTogetherLike","query":"#WeGoTogetherLike"},{"name":"#imcurious","query":"#imcurious"},{"name":"#mm","query":"#mm"},{"name":"#HumanoidCityTour","query":"#HumanoidCityTour"},{"name":"#awesomeindianthings","query":"#awesomeindianthings"},{"name":"#officeformac","query":"#officeformac"},{"name":"Justin Bieber","query":"\"Justin Bieber\""},{"name":"National Margarita","query":"\"National Margarita\""}]}} My code: WebClient wc = new WebClient(); wc.Credentials = new NetworkCredential(this.Auth.UserName, this.Auth.Password); string res = wc.DownloadString(new Uri(link)); //the download string gives me the above JSON string - no problems Trends trends = new Trends(); Trends obj = Deserialise<Trends>(res); private T Deserialise<T>(string json) { T obj = Activator.CreateInstance<T>(); using (MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json))) { DataContractJsonSerializer serialiser = new DataContractJsonSerializer(obj.GetType()); obj = (T)serialiser.ReadObject(ms); ms.Close(); return obj; } } [DataContract] public class Trends { [DataMember(Name = "as_of")] public string AsOf { get; set; } //The As_OF value is returned - But how do I get the //multidimensional array of Names and Queries from the JSON here? }

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  • How to create a new widget for dojox.grid.cells.dijit?

    - by the_drow
    I am trying to create a button widget for dojox.grid. My problems are: 1) The button is only shown when I double click the grid. 2) I can't figure out how to set attributes through declarative markup. It seems that the markupFactory function is responsible for it but it doesn't set the widget's label. The following code demonstrates what I've got so far: dojo.require("dojox.grid.DataGrid"); dojo.require("dojo.data.ItemFileWriteStore"); dojo.require("dijit.form.Button"); dojo.require("dojox.grid.cells.dijit"); dojo.require("dojo.parser"); dojo.declare("dojox.grid.cells.Button", dojox.grid.cells._Widget, { widgetClass: dijit.form.Button, alwaysEditing: true, constructor: function(inCell) { this.inherited(arguments); this.widget = new dijit.form.Button; }, setValue: function(inRowIndex, inValue){ if (this.widget) { this.widget.attr('value', inValue); } else { this.inherited(arguments); } } }); dojox.grid.cells.Button.markupFactory = function(node, cell) { dojox.grid.cells._Widget.markupFactory(node, cell); }

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  • RoR - howto convert some HTML-elements with css to Rails

    - by NicoJuicy
    I have old HTML code with html and css.. <form action="login" method="post"> <div class="field"> <label for="username">Username</label> <input type="text" class="text" id="username" name="username" value="just click login !"/> </div> <span class="fright"> <button class="button" type="submit"><strong>Log In</strong></button> </span> </div> How can i convert this code to decent rails code? I came up with this, but it ain't right :-( : <% form_for :user, @user, :url => { :action => "login" } do |f| %> <% div_for f, :class => "field text" do %> <%= f.text_field :username %> <%= f.password_field :password, :class => "field text" %> <% end %> <span class="fright"> <%= submit_tag '<strong>Inloggen</strong>', :class => "button",:disable_with => 'verwerken...' %></span> <% end %> I'm having problems with the <strong>Inloggen</strong> And with the <% div_for f, :class => "field text" do %>

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  • What are the worst examples of moral failure in the history of software engineering?

    - by Amanda S
    Many computer science curricula include a class or at least a lecture on disasters caused by software bugs, such as the Therac-25 incidents or Ariane 5 Flight 501. Indeed, Wikipedia has a list of software bugs with serious consequences, and a question on StackOverflow addresses some of them too. We study the failures of the past so that we don't repeat them, and I believe that rather than ignoring them or excusing them, it's important to look at these failures squarely and remind ourselves exactly how the mistakes made by people in our profession cost real money and real lives. By studying failures caused by uncaught bugs and bad process, we learn certain lessons about rigorous testing and accountability, and we make sure that our innocent mistakes are caught before they cause major problems. There are kinds of less innocent failure in software engineering, however, and I think it's just as important to study the serious consequences caused by programmers motivated by malice, greed, or just plain amorality. Thus we can learn about the ethical questions that arise in our profession, and how to respond when we are faced with them ourselves. Unfortunately, it's much harder to find lists of these failures--the only one I can come up with is that apocryphal "DOS ain't done 'til Lotus won't run" story. What are the worst examples of moral failure in the history of software engineering?

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  • Is extending a base class with non-virtual destructor dangerous in C++

    - by Akusete
    Take the following code class A { }; class B : public A { }; class C : public A { int x; }; int main (int argc, char** argv) { A* b = new B(); A* c = new C(); //in both cases, only ~A() is called, not ~B() or ~C() delete b; //is this ok? delete c; //does this line leak memory? return 0; } when calling delete on a class with a non-virtual destructor with member functions (like class C), can the memory allocator tell what the proper size of the object is? If not, is memory leaked? Secondly, if the class has no member functions, and no explicit destructor behaviour (like class B), is everything ok? I ask this because I wanted to create a class to extend std::string, (which I know is not recommended, but for the sake of the discussion just bear with it), and overload the +=,+ operator. -Weffc++ gives me a warning because std::string has a non virtual destructor, but does it matter if the sub-class has no members and does not need to do anything in its destructor? -- FYI the += overload was to do proper file path formatting, so the path class could be used like class path : public std::string { //... overload, +=, + //... add last_path_component, remove_path_component, ext, etc... }; path foo = "/some/file/path"; foo = foo + "filename.txt"; //and so on... I just wanted to make sure someone doing this path* foo = new path(); std::string* bar = foo; delete bar; would not cause any problems with memory allocation

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  • How-to display a .gif as background image?

    - by Vito De Tullio
    Hi! I have a javascript "loading" function like this: function splashScreen() { var div = document.createElement('div'); div.appendChild(document.createTextNode("some text")); div.setAttribute("style", "position: fixed; " + "width: 100%; height: 100%; " + "left: 0; top: 0; " + "z-index: 1000; " + "background: #fff url('img/loading.gif') no-repeat center; " + "font-size: x-large; " + "text-align: center; " + "line-height: 3em; " + "opacity: 0.75; " + "filter: alpha(opacity=75); "); document.getElementsByTagName('body')[0].appendChild(div); return true; } I use this function in the form action (onsubmit="return splashScreen()") to show a "rotating logo" while the next page load... The problem is in that "img/loading.gif" and safari (on winXP): in ff and ie I have no problems, and I clearly see the animated gif. In safari I can't see it. If I change the image with a (obviously static) png the image appears... Am I doing something wrong? What's the problem with safari?

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  • Netlogo: error when putting variable in table, only constants allowe??

    - by Chantal
    Hello, Currently I am working on a Netlogo program where I need to use nodes and links for vehicle routing problem. (links are called streets in the program) Here I have some practical problems of how to input variable linkspeed in a table with another node. Constants like 200 etc are fine. Online I found some examples where variables are used, but I do not know why I keep getting the following error: Expected a constant. (or why netlogo expects a constant) Here is the relevant piece of code: extensions [table] streets-own [linkspeed linktoll] nodes-own [netw] ;; In another piece of code linkspeed is assigned successfully to the links to cheapcalc ;; start conditions set costs very high 300000 ;; state 3 unsearched state 2 searching state 1 searched (for later purposes) ask nodes [ set i 0 set j count nodes set netw table:make while [i < j][ table:put netw (i) [3000000 3] set i (i + 1)]] set i 0 let k 0 ask node 35 ;; here i use node 35 as an example. ;; node 35 is connected to node 34, 36, 20 and 50 [table:put netw (35) [0 1] ;; node need to search costs to travel to itself ;; putting constants is ok. while [i < j] [ask my-links [ask both-ends [if (who != 35) [set color blue ;; set temp ([linkspeed] of street 35 who) ;; here my real goal is to put this in stat of i. but i is easier than linkspeed. table:put netw (who) [ i 2 ] ] ] ] set i (i + 1)] ] ;; next node for later, no it is just repetition of the same. end I hope somebody knows what is going on... Kind regards, Chantal

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  • Redirecting to a Facelet is not working when extending FaceletViewHandler

    - by Abel Morelos
    I'm overriding the handleRenderResponse method defined in com.sun.facelets.FaceletViewHandler: protected void handleRenderException(FacesContext context, Exception ex) I'm overriding this method so I can redirect the user to a custom error page (which contain the desired look and feel and other stuff). This is the way I'm trying to String errorPage = "/error.xhtml"; String contextPath = context.getExternalContext().getRequestContextPath(); String errorPagePath = contextPath+errorPage; context.getExternalContext().redirect(errorPagePath); The previous code is what I'm using to perform the redirect to this custom error page. Anyway, when I perform the redirect I'm prompted with a download dialog (this is with Internet Explorer, in Firefox the page does not display properly or as I would expect). I tried changing "/error.xhtml" to "/error.jsf" but in that case I get a 404 error. Somehow I think that the XHTML file is not being handled to the Facelets ViewHandler after the redirect, if I open the downloaded xhtml file I can see that the EL expressions were not resolved and the the ui tags were not handled. I don't have problems with other pages in my application, only when doing the redirect programatically. Important data from my web.xml: facelets.VIEW_MAPPINGS is set to *.xhtml javax.faces.DEFAULT_SUFFIX is set to .xhtml servlet-mapping for the "Faces Servlet" is ".jsf" and "/faces/"

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  • jQuery JSON .each problem

    - by Aran
    I have a JSON object that looks like this. [ { "id" : "23", "event_id" : "0", "sport_title" : null, "event_title" : null, "title" : "Under 1 day!", "content" : "It\\'s all hotting up and battle commences in under one day!", "link" : "" }, { "id" : "20", "event_id" : "0", "sport_title" : null, "event_title" : null, "title" : "Getting Exciting", "content" : "Less than two days till it all kicks off, with cricket....", "link" : "" }] and I am trying to get the details out of this JSON Object and prepend them to a <ul> the code that I am currently trying looks like this and is having problems var writeup_list = writeuplist; $.getJSON('../json/getWriteups.json', function(data) { $.each(data.items, function(i, item) { writeup_list.html(function() { var output; output = '<li><a href="/writeups/index.php#writeup_' + item.id + '">'; if(item.sport_title != null) { output += item.sport_title + ' - '; } output += item.title + '</a></li>'; return output; }); }); }); writeuplist is just the ul object. I am also worried about overriding information that is already in the list or just adding again. Don't want to keep adding the same data. What is a good way to avoid this? I seem to be having a problem in getting the data out of the JSON file I believe it has something to do with the way am trying to access it in the .each function. Can anyone spot where am going wrong?

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