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• dotNet Templated, Repeating, Databound ServerControl: Modifying underlying ServerControl data per te

  - by Campbeln

  I have a server control that wraps an underlying class which manages a number of indexes to track where it is in a dataset (ie: RenderedRecordCount, ErroredRecordCount, NewRecordCount, etc.). I've got the server control rendering great, but OnDataBinding I'm having an issue as to seems to happen after CreateChildControls and before Render (both of which properly manage the iteration of the underlying indexes). While I'm somewhat familiar with the ASP.NET page lifecycle, this one seems to be beyond me at the moment. So... How do I hook into the iterative process OnDataBinding uses so I can manage the underlying indexes? Will I have to iterate over the ITemplates myself, managing the indexes as I go or is there an easier solution? [edit: Agh... writing the problem out is very cathartic... I'm thinking this is exactly what I will need to do...] Also... I implemented the iteration of the underlying indexes during CreateChildControls originally in the belief that was the proper place to hook in for events like OnDataBinding (thinking it was done as the controls were being .Add'd). Now it seems that this may actually be unnecessary. So I guess the secondary question is: What happens during CreateChildControls? Are the unadulterated (read: with various <%-tags in place) controls added to the .Controls collection without any other processing?

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• Factory.next not working in FactoryGirl 4.x and Rails 3.0. Anyone know the replacement?

  - by cchapman900

  I'm very new to Rails and am following along in the Ruby on Rails 3 Tutorial book by Michael Hartl and am running into a little bump while using the factory_girl gem. Specifically, I'm not sure how to update the code Factory.next(...) Before coming to this, I did run into a little problem between the older version of FactoryGirl used in the book and the current 4.1 version I'm using now, but was able to resolve it. Specifically, the old way of writing code as user = Factory(:user) needed to be updated to user = FactoryGirl.create(:user) That was fine, but now I'm coming to the code (as written in the book): spec/controllers/users_controler_spec.rb . @users << Factory(:user, :email => Factory.next(:email)) . which I've tried updating to . @users << FactoryGirl.create(:user, :email => FactoryGirl.next(:email)) . but get the error: Failure/Error: @users << FactoryGirl.create(:user, :email => FactoryGirl.next(:email)) NoMethodError: undefined method `next' for FactoryGirl:Module I've tried a few different variations but still can't quite get it. Is the problem I'm having with FactoryGirl and just not using the gem correctly or does it have something to do with the Ruby methods?

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• Best way to do interprocess communication on Mac OS X

  - by jbrennan

  I'm looking at building a Cocoa application on the Mac with a back-end daemon process (really just a mostly-headless Cocoa app, probably), along with 0 or more "client" applications running locally (although if possible I'd like to support remote clients as well; the remote clients would only ever be other Macs or iPhone OS devices). The data being communicated will be fairly trivial, mostly just text and commands (which I guess can be represented as text anyway), and maybe the occasional small file (an image possibly). I've looked at a few methods for doing this but I'm not sure which is "best" for the task at hand. Things I've considered: Reading and writing to a file (…yes), very basic but not very scalable. Pure sockets (I have no experience with sockets but I seem to think I can use them to send data locally and over a network. Though it seems cumbersome if doing everything in Cocoa Distributed Objects: seems rather inelegant for a task like this NSConnection: I can't really figure out what this class even does, but I've read of it in some IPC search results I'm sure there are things I'm missing, but I was surprised to find a lack of resources on this topic.

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• Is there a fast alternative to creating a Texture2D from a Bitmap object in XNA?

  - by Matthew Bowen

  I've looked around a lot and the only methods I've found for creating a Texture2D from a Bitmap are: using (MemoryStream s = new MemoryStream()) { bmp.Save(s, System.Drawing.Imaging.ImageFormat.Png); s.Seek(0, SeekOrigin.Begin); Texture2D tx = Texture2D.FromFile(device, s); } and Texture2D tx = new Texture2D(device, bmp.Width, bmp.Height, 0, TextureUsage.None, SurfaceFormat.Color); tx.SetData<byte>(rgbValues, 0, rgbValues.Length, SetDataOptions.NoOverwrite); Where rgbValues is a byte array containing the bitmap's pixel data in 32-bit ARGB format. My question is, are there any faster approaches that I can try? I am writing a map editor which has to read in custom-format images (map tiles) and convert them into Texture2D textures to display. The previous version of the editor, which was a C++ implementation, converted the images first into bitmaps and then into textures to be drawn using DirectX. I have attempted the same approach here, however both of the above approaches are significantly too slow. To load into memory all of the textures required for a map takes for the first approach ~250 seconds and for the second approach ~110 seconds on a reasonable spec computer. If there is a method to edit the data of a texture directly (such as with the Bitmap class's LockBits method) then I would be able to convert the custom-format images straight into a Texture2D and hopefully save processing time. Any help would be very much appreciated. Thanks

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• mysql subselect alternative

  - by Arnold

  Hi, Lets say I am analyzing how high school sports records affect school attendance. So I have a table in which each row corresponds to a high school basketball game. Each game has an away team id and a home team id (FK to another "team table") and a home score and an away score and a date. I am writing a query that matches attendance with this seasons basketball games. My sample output will be (#_students_missed_class, day_of_game, home_team, away_team, home_team_wins_this_season, away_team_wins_this_season) I now want to add how each team did the previous season to my analysis. Well, I have their previous season stored in the game table but i should be able to accomplish that with a subselect. So in my main select statement I add the subselect: SELECT COUNT(*) FROM game_table WHERE game_table.date BETWEEN 'start of previous season' AND 'end of previous season' AND ( (game_table.home_team = team_table.id AND game_table.home_score > game_table.away_score) OR (game_table.away_team = team_table.id AND game_table.away_score > game_table.home_score)) In this case team-table.id refers to the id of the home_team so I now have all their wins calculated from the previous year. This method of calculation is neither time nor resource intensive. The Explain SQL shows that I have ALL in the Type field and I am not using a Key and the query times out. I'm not sure how I can accomplish a more efficient query with a subselect. It seems proposterously inefficient to have to write 4 of these queries (for home wins, home losses, away wins, away losses). I am sure this could be more lucid. I'll absolutely add color tomorrow if anyone has questions

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• Custom Calculations in a Matrix - Reporting Services 2005

  - by bfrancis

  I am writing a report to show gas usage (in gallons) used by each department. The request is to view each month and the gallons used by each department. A column is required to display what each departments target goal is, based on the gallons of gas they have used in a past time frame. Each departments target goal is x percent less than the total gallons used for said time frame. I currently have a matrix in Reporting Services with departments making up rows, months making up columns, and gallons filling the details. The matrix is being filled by dataset1. I have the data grouping as is requested for each month by each department. My problem is calculating the target goal. My thought was to create a second dataset (dataset2) that returns the gallons used based on the time frame requested. I grouped this data by department. I was hoping I could use the department field in each dataset to make sure the appropriate numbers were used. I added a new column which shows up next to the gallons field. As I attempted to build the Expression I found out that I could only grab the gallons used from dataset2 if I was summing the gallons field. This gives me the total gallons used by every department combined. I have tried to find resources with similar examples of what I am trying to accomplish but I cannot seem to come across one. I am trying to keep this as detailed as possible without making it too wordy. I would be more than happy to clarify or explain into further detail what I have written above if it is needed. If anyone has links, comments, or suggestions they would be greatly appreciated. A very simple visual or what I am hoping to accomplish is below. The months and departments would expand based on the data returned. months ------------------------------ departments| gallons/month | target goal

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• C# TcpClient, getting back the entire response from a telnet device

  - by Dan Bailiff

  I'm writing a configuration tool for a device that can communicate via telnet. The tool sends a command via TcpClient.GetStream().Write(...), and then checks for the device response via TcpClient.GetStream().ReadByte(). This works fine in unit tests or when I'm stepping through code slowly. If I run the config tool such that it performs multiple commands consecutively, then the behavior of the read is inconsistent. By inconsistent I mean sometimes the data is missing, incomplete or partially garbled. So even though the device performed the operation and responded, my code to check for the response was unreliable. I "fixed" this problem by adding a Thread.Sleep to make sure the read method waits long enough for the device to complete its job and send back the whole response (in this case 1.5 seconds was a safe amount). I feel like this is wrong, blocking everything for a fixed time, and I wonder if there is a better way to get the read method to wait only long enough to get the whole response from the device. private string Read() { if (!tcpClient.Connected) throw (new Exception("Read() failed: Telnet connection not available.")); StringBuilder sb = new StringBuilder(); do { ParseTelnet(ref sb); System.Threading.Thread.Sleep(1500); } while (tcpClient.Available > 0); return sb.ToString(); } private void ParseTelnet(ref StringBuilder sb) { while (tcpClient.Available > 0) { int input = tcpClient.GetStream().ReadByte(); switch (input) { // parse the input // ... do other things in special cases default: sb.Append((char)input); break; } } }

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• Reading Code - helpful visualizers and browser tools

  - by wishi_

  Hi! I find myself reading 10 times more code than writing. My IDEs all are optimized to make me edit code - with completion, code assist, outlines etc. However if I'm checking out a completely new project: getting into the application's logics isn't optimized with these IDE features. Because I cannot extend what I don't fully understand. If you for example check out a relatively new project, frama-c, you realize that it has got plugins that are helpful to gain insight into "unfamiliar code": http://frama-c.com/plugins.html - However of course the project has a different scope. What I'm fully aware of. I'm looking for something that does helpful things for code-reading. Like: providing a graph, - reverse engineering UML e g., showing variable scopes showing which parts are affected by attempted modifications visualizing data-flow semantics showing tag-lists of heavily utilized functions ... My hope is that something like that exists. - That there're some Eclipse plugins I don't know or that there's a code-browser that has some of these features?

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• .NET WebBrowser control with Adobe SVG Viewer

  I'm having problems with SVG files loading in a .NET 2.0 WebBrowser control. If I create a new WinForms application project, drag a WebBrowser control and a button onto the Form1.cs design surface, and add a line to the button's on-click handler to set the Url property of the WebBrowser control to an SVG file, I get two IE script errors at runtime (as in, the dialog you get when there is a Javascript problem). The only line of code I'm writing is therefore: webBrowser1.Url = new Uri(@"http://wiki.allegro.cc/pub/f/fb/Grozilla.svg"); This SVG file loads fine if I browse directly to the link with IE; the errors I get via my test app are: line 2, char 1, error: Invalid character, followed by line 1, char 1, error: Object expected (assuming I answer yes to the prompt to 'continue running scripts on this page'). I'm using IE 7.0.5730.13, Adobe SVG Viewer 3.03 build 94, Visual Studio 2008. Can anyone replicate this? Has anyone seen it/got any idea how to fix it? (edit: previously setting the URL in the constructor for the purposes of the example, but this raised the question of whether or not the control had finished initialising, so have changed the example to use a button - the problem still occurs. This bug originally appeared in production code so the example program I wrote was an attempt to isolate the issue and reproduce it as simply as possible.) (edit 2: having tested on several different machines, this problems seems to be related to IE7 - run IE6, and everything works fine.)

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• best way to add and delete text lines with jquery product configurator

  - by Daniel White

  I am creating a product configurator with Jquery. My users can add custom text lines to their product. So you could create say... 4 text lines with custom text. I need to know what the best way to add and delete these lines would be. Currently I have the following code for adding lines... //Add Text Button $('a#addText').live('click', function(event) { event.preventDefault(); //Scroll up the text editor $('.textOptions').slideUp(); $('#customText').val(''); //count how many items are in the ul textList var textItems = $('ul#textList li').size(); var nextNumber = textItems + 1; if(textItems <= 5) { //Change input to reflect current text being changed $('input#currentTextNumber').val(nextNumber); //Append a UL Item to the textList $('ul#textList').append('<li id="textItem'+nextNumber+'">Text Line. +$5.00 <a class="deleteTextItem" href="'+nextNumber+'">Delete</a></li>'); //Scroll down the text editor $('.textOptions').slideDown(); }else { alert('you can have a maximum of 6 textual inputs!'); } }); I'm probably not doing this the best way, but basically i have an empty UL list to start with. So when they click "Add Text Line" it finds out how many list elements are in the unordered list, adds a value of 1 to that and places a new list element with the id TextItem1 or TextItem2 or whatever number we're on. The problem i'm running into is that when you click delete item, it screws everything up because when you add an item again all the numbers aren't correct. I thought about writing some kind of logic that says all the numbers above the one you want deleted get 1 subtracted from their value and all the numbers below stay the same. But I think i'm just going about this the wrong way. Any suggestions on the easiest way to add and delete these text lines is appreciated.

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• Turbogears 2.0 with Python 2.6

  - by AKSK

  I've tried to install TurboGears 2.0 with Python 2.6 on both Windows 7 and Windows XP, but both give the same error: File "D:\PythonProjects\tg2env\Scripts\paster-script.py", line 8, in <module> load_entry_point('pastescript==1.7.3', 'console_scripts', 'paster')() File "D:\PythonProjects\tg2env\lib\site-packages\pastescript-1.7.3-py2.6.egg\paste\script\command.py", line 73, in run commands = get_commands() File "D:\PythonProjects\tg2env\lib\site-packages\pastescript-1.7.3-py2.6.egg\paste\script\command.py", line 115, in get_ plugins = pluginlib.resolve_plugins(plugins) File "D:\PythonProjects\tg2env\lib\site-packages\pastescript-1.7.3-py2.6.egg\paste\script\pluginlib.py", line 81, in res pkg_resources.require(plugin) File "D:\PythonProjects\tg2env\lib\site-packages\setuptools-0.6c9-py2.6.egg\pkg_resources.py", line 626, in require File "D:\PythonProjects\tg2env\lib\site-packages\setuptools-0.6c9-py2.6.egg\pkg_resources.py", line 524, in resolve pkg_resources.DistributionNotFound: zope.sqlalchemy>=0.4: Not Found for: City_Guide (did you run python setup.py develop?) Now, according to the documentation on the main site, TurboGears 2.0 supports Python 2.6 in this page: TurboGears works with any version of python between 2.4 and 2.6. The most widely deployed version of python at the moment of this writing is version 2.5. Both python 2.4 and python 2.6 require additional steps which will be covered in the appropriate sections. But they never mention those steps in the documentation.

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• multithreading issue

  - by vbNewbie

  I have written a multithreaded crawler and the process is simply creating threads and having them access a list of urls to crawl. They then access the urls and parse the html content. All this seems to work fine. Now when I need to write to tables in a database is when I experience issues. I have 2 declared arraylists that will contain the content each thread parse. The first arraylist is simply the rss feed links and the other arraylist contains the different posts. I then use a for each loop to iterate one while sequentially incrementing the other and writing to the database. My problem is that each time a new thread accesses one of the lists the content is changed and this affects the iteration. I tried using nested loops but it did not work before and this works fine using a single thread.I hope this makes sense. Here is my code: SyncLock dlock For Each l As String In links finallinks.Add(l) Next End SyncLock SyncLock dlock For Each p As String In posts finalposts.Add(p) Next End SyncLock ... Dim i As Integer = 0 SyncLock dlock For Each rsslink As String In finallinks postlink = finalposts.Item(i) i = i + 1 finallinks and finalposts are the two arraylists. I did not include the rest of the code which shows the threads working but this is the essential part where my error occurs which is basically here postlink = finalposts.Item(i) i = i + 1 ERROR: index was out of range. Must be non-negative and less than the size of the collection Is there an alternative?

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• C# Serialization lock out

  - by Greycrow

  When I try to Serialize a class to an xml file I get the exception: The process cannot access the file 'C:\settings.xml' because it is being used by another process. Settings currentSettings = new Settings(); public void LoadSettings() { //Load Settings from XML file try { Stream stream = File.Open("settings.xml", FileMode.Open); XmlSerializer s = new XmlSerializer(typeof(Settings)); currentSettings = (Settings)s.Deserialize(stream); stream.Close(); } catch //Can't read XML - use default settings { currentSettings.Name = GameSelect.Items[0].ToString(); currentSettings.City = MapSelect.Items[0].ToString(); currentSettings.Country = RaceSelect.Items[0].ToString(); } } public void SaveSettings() { //Save Settings to XML file try { Stream stream = File.Open("settings.xml", FileMode.Create); XmlSerializer x = new XmlSerializer(typeof(Settings)); x.Serialize(stream, currentSettings); stream.Close(); } catch { MessageBox.Show("Unable to open XML File - File in use by other process"); } It appears that when I Deserialize it locks the file for writing back, even if I closed the stream. Thanks in advance.

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• Disposing underlying object from finalizer in an immutable object

  - by Juan Luis Soldi

  I'm trying to wrap around Awesomium and make it look to the rest of my code as close as possible to NET's WebBrowser since this is for an existing application that already uses the WebBrowser. In this library, there is a class called JSObject which represents a javascript object. You can get one of this, for instance, by calling the ExecuteJavascriptWithResult method of the WebView class. If you'd call it like myWebView.ExecuteJavascriptWithResult("document", string.Empty).ToObject(), then you'd get a JSObject that represents the document. I'm writing an immutable class (it's only field is a readonly JSObject object) called JSObjectWrap that wraps around JSObject which I want to use as base class for other classes that would emulate .NET classes such as HtmlElement and HtmlDocument. Now, these classes don't implement Dispose, but JSObject does. What I first thought was to call the underlying JSObject's Dispose method in my JSObjectWrap's finalizer (instead of having JSObjectWrap implement Dispose) so that the rest of my code can stay the way it is (instead of having to add using's everywhere and make sure every JSObjectWrap is being properly disposed). But I just realized if more than two JSObjectWrap's have the same underlying JSObject and one of them gets finalized this will mess up the other JSObjectWrap. So now I'm thinking maybe I should keep a static Dictionary of JSObjects and keep count of how many of each of them are being referenced by a JSObjectWrap but this sounds messy and I think could cause major performance issues. Since this sounds to me like a common pattern I wonder if anyone else has a better idea.

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• Copy SQL Server data from one server to another on a schedule

  - by rwmnau

  I have a pair of SQL Servers at different webhosts, and I'm looking for a way to periodically update the one server using the other. Here's what I'm looking for: As automated as possible - ideally, without any involvement on my part once it's set up. Pushes a number of databases, in their entirely (including any schema changes) from one server to the other Freely allows changes on the source server without breaking my process. For this reason, I don't want to use replication, as I'd have to break it every time there's an update on the source, and then recreate the publication and subscription One database is about 4GB in size and contains binary data. I'm not sure if there's a way to export this to a script, but it would be a mammoth file if I did. Originally, I was thinking of writing something that takes a scheduled full backup of each database, FTPs the backups from one server to the other once they're done, and then the new server picks it up and restores it. The only downside I can see to this is that there's no way to know that the backups are done before starting to transfer them - can these backups be done synchronously? Also, the server being refreshes is our test server, so if there's some downtime involved in moving the data, that's fine. Does anybody out there have a better idea, or is what I'm currently considering the best non-replication way to go? Thanks for your help, everybody. UPDATE: I ended up designing a custom solution to get this done using BAT files, 7Zip,command line FTP, and OSQL, so it runs in a completely automatic way and aggregates the data from a dozen servers across the country. I've detailed the steps in a blog entry. Thanks for all your input!

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• Modify post data with a custom MVC extension?

  - by Jaxidian

  So I'm looking into writing some custom MVC extensions and the first one I'm attempting to tackle is a FormattedTextBox to handle things such as currency, dates, and times. I have the rendering of it working perfectly, formatting it, working with strong types and everything all golden. However, the problem I'm now running into is cleaning up the formatted stuff when the page posts the data back. Take for example, a currency format. Let's use USD for these examples. When an object has a property as a decimal, the value would be 79.95. Your edit view would be something like: <%= Html.FormattedTextBox(model => Model.Person.HourlyWage, "{0:C}") %> This is all well and good for the GET request, but upon POST, the value is going to be $79.95, which when you assign to that decimal, gets unhappy very quickly and ends up shoving a 0 in there. So my question is, how do I get code working somewhere to work with that value before the MVC Framework goes and starts shoving it back into my ViewModel? I'd much rather this be done server-side than client-side. Thanks!!

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• .NET proxy detection

  - by Ziplin

  I am having an issue with .NET detecting the proxy settings configured through internet explorer. I'm writing a client application that supports proxies, and to test I set up an array of 9 squid servers to support various authentication methods for HTTP and HTTPs. I have a script that updates IE to whichever configuration I choose (which proxy, detection via "Auto", PAC, or hardcode). I have tried the 3 methods below to detect the IE configuration through .NET. On occassion I notice that .NET picks up the wrong set of proxy servers. IE has the correct settings, and if I browse the web with IE, I can see I am hitting the correct servers via wireshark. WebRequest.GetSystemWebProxy().GetProxy(destination); GlobalProxySelection.Select.GetProxy(destination); WebRequest.DefaultWebProxy Here are the following tips I have: My script sets a PAC file on a webserver, and updates the configuration in IE, then clears IE's cache .NET seems to get "stuck" on a certain proxy configuration, and I have to set another configuration for .NET to realize there was a change. Occasionally it seems to pick some random set of servers (I'm sure they're not random, just a set of servers I used once and are in some cached PAC file or something). As in, I will check the proxy for the destination "https://www.secure.com" and I may have IE configured for and thus expect to get "http://squidserver:18" and instead it will return "http://squidserver:28" (port 18 runs NTLM, 28 runs without authentication). All the squid servers work. This does not appear to be an issue on XP, only Vista, 2003, and windows 7. Hardcoding the proxy servers in IE ALWAYS works Time always solves the issue - if I leave the computer for about 20 or 30 minutes and come back, .NET picks up the correct proxy settings, as if a cached PAC script expired.

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• iPhone and OpenCV

  - by gn-mithun

  Hello, I am writing an application to create a movie file from a bunch of images on an iPhone. I am using OpenCv. I downloaded openCv static libraries for arm(iPhones native instruction architecture) and the libraries were generated just fine. There were no problems linking to them libraries. As a first step, i was trying to create a .avi file using one image, to see if it works. But cvCreateVideoWriter always returns me a NULL value. I did some searchin and i believe its due to the codec not being present. I am trying this on the iPhone simulator. this is what i do... (void)viewDidLoad { [super viewDidLoad]; UIImage *anImage = [UIImage imageNamed:@"1.jpg"]; IplImage *img_color = [self CreateIplImageFromUIImage:anImage]; //The image gets created just fine CvVideoWriter *writer = cvCreateVideoWriter("out.avi",CV_FOURCC('P','I','M','1'), 25,cvSize(320,480),1); //writer is always null int result = cvWriteFrame(writer, img_color); NSLog(@"\n%d",result); //hence this is also 0 all the time cvReleaseVideoWriter(&writer); } I am not sure about the the second parameter. What sort of codec or what exactly it does... I am a n00B in this. Any suggestions?

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• Django - how to write users and profiles handling in best way?

  - by SpankMe

  Hey, I am writing simple site that requires users and profiles to be handled. The first initial thought is to use django's build in user handling, but then the user model is too narrow and does not contain fields that I need. The documentation mentions user profiles, but user profiles section has been removed from djangobook covering django 1.0 (ideally, the solution should work with django 1.2), and the Internet is full of different solutions, not making the choice easier (like user model inheritance, user profiles and django signals, and so on). I would like to know, how to write this in good, modern, fast and secure way. Should I try to extend django builtin user model, or maybe should I create my own user model wide enough to keep all the information I need? Below you may find some specifications and expectations from the working solution: users should be able to register and authenticate every user should have profile (or model with all required fields) users dont need django builtin admin panel, but they need to edit their profiles/models via simple web form Please, let me know how do you solve those issues in your applications, and what is the best current way to handle users with django. Any links to articles/blogs or code examples are highly appreciated!

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• Alternative to MS Project 2007 for production scheduling?

  - by john c

  OK... Im coming to grips with the fact that MS Project 2007 may not be the correct tool for my production scheduling. We serve 120 to 150 projects a year with durations from 6 weeks to 12 months. The task are simple (6 to 8 per project) and the resource pool is stable (15 to 20 people). It's really an assembly line product but with extremely varied durations. I need to be able to prioritize the projects for production and run projects concurrently to fully utilize my resources. What are the feelings of the stackoverflow community. Am I using the wrong program? I was really hoping to make this simple for non-programer types to input project data into a form and have the schedule software automated enough to make most of the decisions. Is there a better solution available commercially? I'd like to hold on writing a custom spreadsheet as a last resort but if that's the best route then so be it. Thank you so much for your input.

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• int considered harmful?

  - by Chris Becke

  Working on code meant to be portable between Win32 and Win64 and Cocoa, I am really struggling to get to grips with what the @#$% the various standards committees involved over the past decades were thinking when they first came up with, and then perpetuated, the crime against humanity that is the C native typeset - char, short, int and long. On the one hand, as a old-school c++ programmer, there are few statements that were as elegant and/or as simple as for(int i=0; i<some_max; i++) but now, it seems that, in the general case, this code can never be correct. Oh sure, given a particular version of MSVC or GCC, with specific targets, the size of 'int' can be safely assumed. But, in the case of writing very generic c/c++ code that might one day be used on 16 bit hardware, or 128, or just be exposed to a particularly weirdly setup 32/64 bit compiler, how does use int in c++ code in a way that the resulting program would have predictable behavior in any and all possible c++ compilers that implemented c++ according to spec. To resolve these unpredictabilities, C99 and C++98 introduced size_t, uintptr_t, ptrdiff_t, int8_t, int16_t, int32_t, int16_t and so on. Which leaves me thinking that a raw int, anywhere in pure c++ code, should really be considered harmful, as there is some (completely c++xx conforming) compiler, thats going to produce an unexpected or incorrect result with it. (and probably be a attack vector as well)

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• Why is creating a ring buffer shared by different processes so hard (in C++), what I am doing wrong?

  - by recipriversexclusion

  I am being especially dense about this but it seems I'm missing an important, basic point or something, since what I want to do should be common: I need to create a fixed-size ring buffer object from a manager process (Process M). This object has write() and read() methods to write/read from the buffer. The read/write methods will be called by independent processes (Process R and W) I have implemented the buffer, SharedBuffer<T&>, it allocates buffer slots in SHM using boost::interprocess and works perfectly within a single process. I have read the answers to this question and that one on SO, as well as asked my own, but I'm still in the dark about how to have different processes access methods from a common object. The Boost doc has an example of creating a vector in SHM, which is very similar to what I want, but I want to instantiate my own class. My current options are: Use placement new, as suggested by Charles B. to my question; however, he cautions that it's not a good idea to put non-POD objects in SHM. But my class needs the read/write methods, how can I handle those? Add an allocator to my class definition, e.g. have SharedBuffer<T&, Alloc> and proceed similarly to the vector example given in boost. This sounds really complicated. Change SharedBuffer to a POD class, i.e. get rid of all the methods. But then how to synchronize reading and writing between processes? What am I missing? Fixed-length ring buffers are very common, so either this problem has a solution or else I'm doing something wrong.

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• Casting to a struct from LPVOID - C

  - by Jamie Keeling

  Hello, I am writing a simple console application which will allow me to create a number of threads from a set of parameters passed through the arguments I provide. DWORD WINAPI ThreadFunc(LPVOID threadData) { } I am packing them into a struct and passing them as a parameter into the CreateThread method and trying to unpack them by casting them to the same type as my struct from the LPVOID. I'm not sure how to cast it to the struct after getting it through so I can use it in the method itself, i've tried various combinations (Example attatched) but it won't compile. Struct: #define numThreads 1 struct Data { int threads; int delay; int messages; }; Call to method: HANDLE hThread; DWORD threadId; struct Data *tData; tData->threads = numThreads; tData->messages = 3; tData->delay = 1000; // Create child thread hThread = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc, // lpStartAddress &tData, // lpParameter 0, // dwCreationFlags &threadId // lpThreadId (returned by function) ); My attempt: DWORD WINAPI ThreadFunc(LPVOID threadData) { struct Data tData = (struct Data)threadData; int msg; for(msg = 0; msg<5; msg++) { printf("Message %d from child\n", msg); } return 0; } Compiler error: error C2440: 'type cast' : cannot convert from 'LPVOID' to 'Data' As you can see I have implemented a way to loop through a number of messages already, I'm trying to make things slightly more advanced and add some further functionality.

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• CallbackValidator called with empty string

  - by Paolo Tedesco

  I am writing a custom configuration section, and I would like to validate a configuration property with a callback, like in this example: using System; using System.Configuration; class CustomSection : ConfigurationSection { [ConfigurationProperty("stringValue", IsRequired = false)] [CallbackValidator(Type = typeof(CustomSection), CallbackMethodName = "ValidateString")] public string StringValue { get { return (string)this["stringValue"]; } set { this["stringValue"] = value; } } public static void ValidateString(object value) { if (string.IsNullOrEmpty((string)value)) { throw new ArgumentException("string must not be empty."); } } } class Program { static void Main(string[] args) { CustomSection cfg = (CustomSection)ConfigurationManager.GetSection("customSection"); Console.WriteLine(cfg.StringValue); } } And my App.config file looks like this: <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="customSection" type="CustomSection, config-section"/> </configSections> <customSection stringValue="lorem ipsum"/> </configuration> My problem is that when the ValidateString function is called, the value parameter is always an empty string, and therefore the validation fails. If i just remove the validator, the string value is correctly initialized to the value in the configuration file. What am I missing?

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• SQL select row into a string variable without knowing columns

  - by Brandi

  Hello, I am new to writing SQL and would greatly appreciate help on this problem. :) I am trying to select an entire row into a string, preferably separated by a space or a comma. I would like to accomplish this in a generic way, without having to know specifics about the columns in the tables. What I would love to do is this: DECLARE @MyStringVar NVARCHAR(MAX) = '' @MyStringVar = SELECT * FROM MyTable WHERE ID = @ID AS STRING But what I ended up doing was this: DECLARE @MyStringVar = '' DECLARE @SecificField1 INT DECLARE @SpecificField2 NVARCHAR(255) DECLARE @SpecificField3 NVARCHAR(1000) ... SELECT @SpecificField1 = Field1, @SpecificField2 = Field2, @SpecificField3 = Field3 FROM MyTable WHERE ID = @ID SELECT @StringBuilder = @StringBuilder + CONVERT(nvarchar(10), @Field1) + ' ' + @Field2 + ' ' + @Field3 Yuck. :( I have seen some people post stuff about the COALESCE function, but again, I haven't seen anyone use it without specific column names. Also, I was thinking, perhaps there is a way to use the column names dynamically getting them by: SELECT [COLUMN_NAME] FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'MyTable' It really doesn't seem like this should be so complicated. :( What I did works for now, but thanks ahead of time to anyone who can point me to a better solution. :) EDIT: Got it fixed, thanks to everyone who answered. :)

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