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• rs232 communication, general timing question

  - by Sunny Dee

  Hi, I have a piece of hardware which sends out a byte of data representing a voltage signal at a frequency of 100Hz over the serial port. I want to write a program that will read in the data so I can plot it. I know I need to open the serial port and open an inputstream. But this next part is confusing me and I'm having trouble understanding the process conceptually: I create a while loop that reads in the data from the inputstream 1 byte at a time. How do I get the while loop timing so that there is always a byte available to be read whenever it reaches the readbyte line? I'm guessing that I can't just put a sleep function inside the while loop to try and match it to the hardware sample rate. Is it just a matter of continuing reading the inputstream in the while loop, and if it's too fast then it won't do anything (since there's no new data), and if it's too slow then it will accumulate in the inputstream buffer? Like I said, i'm only trying to understand this conceptually so any guidance would be much appreciated! I'm guessing the idea is independent of which programming language I'm using, but if not, assume it is for use in Java. Thanks!

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• What's the best way to develop a debugging window for an ajax ASP.Net MVC application

  - by KallDrexx

  While developing my ASP.NET MVC, I have started to see the need for a debugging console window to assist in figuring out what is going right and wrong in my code. I read the last few chapters of the Pro Asp.net MVC book, and the author details how to use http modules to show page load/creation times and linq to sql query logs, both of which I definitely want to be able to see. However, since I am loading a lot of small sections of my page individually with ajax I don't want the debug information right there in the middle of my screen. So the idea I came up with was to have a separate browser window (open-able by a link or some javascript) with a console log, that can contain logged entries both from javascript and from the asp.net mvc run. The former should be relatively easy, but I'm having trouble coming up with a way to log the asp.net information in ajax requests. The direction I have been thinking of going is to create an httpmodule (like the Pro MVC book does), and have that module contain some that append the javascript's log to console calls with the messages. The issue I see with this is finding a way to get the log messages from the controller's action methods to the httpmodule's methods. The only way I see to do this is with a singleton, but I'm not sure if singletons are bad practice for a stateless web application. Furthermore, it seems like if I return json with my ajax calls (instead of pure html) then that won't work at all anyways and unless there is a way to add data to an existing json structure inside the httpmodule. How does everyone else handle this type of debugging in heavily ajax applications? For reference, the javascript library I am using is jquery.

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• Unable to connect on socket across different networks.

  - by maleki

  I am having trouble connecting my online application to others across another network. I am able to give them the hostAddress to connect when we are on the same network but when we are doing it across the internet the generated host address doesn't allow a connection, nor does using the ip address gotten from online sites such as whatismyip.com My biggest issue isn't debugging this code, because it works over intra-network but The server doesn't see attempts when we try to move to different networks. Also, the test ip I am using is 2222. InetAddress addr = InetAddress.getLocalHost(); String hostname = addr.getHostName(); System.out.println("Hostname: " + hostname); System.out.println("IP: " + addr.getHostAddress()); I display the host to the server when it is starting if (isClient) { System.out.println("Client Starting.."); clientSocket = new Socket(host, port_number); } else { System.out.println("Server Starting.."); echoServer = new ServerSocket(port_number); clientSocket = echoServer.accept(); System.out.println("Warning, Incoming Game.."); }

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• TFS and Forms Authentication

  - by George

  I don't know squat about TFS, other than as a user who has performed simple check in/outs. I just installed it locally and would like to do joint development with a friend. I was having trouble making my TFS web site on port 8080 visible (the whole scoop is here if your interested) and I wonder if it could be related to the fact that TFS is probably using Windows Authentication to identify the user. Can TFS be set up to use forms authentication? We probably need to set up a VPN, though that's a learning curve too. To use TFS, do our machines have to belong to a domain? We're not admin types, though he is better than me, though I would be interested in any feedback or advice on which path is likely to pan out the best. I already got AxoSoft OneTime working in this type of an environment and it suits us well, but I am tempted at all the bells & whistles with TFS and the ability to tie tracked bug items to code changes. As far as finding a good way to share code, do sites like SourceForge allow one to keep code secure among members only?

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• Is there a Standard or Best Practice for Perl Progams, as opposed to Perl Modules?

  - by swestrup

  I've written any number of perl modules in the past, and more than a few stand-alone perl programs, but I've never released a multi-file perl program into the wild before. I have a perl program that is almost at the beta stage and is going to be released open source. It requires a number of data files, as well as some external perl modules -- some I've written myself, and some from CPAN -- that I'll have to bundle with it so as to ensure that someone can just download my program and install it without worrying about hunting for obscure modules. So, it sounds to me like I need to write an installer to copy all the files to standard locations so that a user can easily install everything. The trouble is, I have no idea what the standard practice would be for this. I have found lots of tutorials on perl module standards, but none on perl program standards. Does anyone have any pointers to standard paths, installation proceedures, etc, for perl programs? This is going to be complicated by the fact that the program is multi-platform. I've been testing it in Linux, but its designed to work equally well in Windows.

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• Qt Jambi: Accessing the content of QNetworkReply

  - by Richard

  Hi All, I'm having trouble accessing the content of QNetworkReply objects. Content appears to be empty or zero. According to the docs (translating from c++ to java) I think I've got this set up correctly, but to no avail. Additionally an "Unknown error" is being reported. Any ideas much appreciated. Code: public class Test extends QObject { private QWebPage page; public Test() { page = new QWebPage(); QNetworkAccessManager nac = new QNetworkAccessManager(); nac.finished.connect(this, "requestFinished(QNetworkReply)"); page.setNetworkAccessManager(nac); page.loadProgress.connect(this, "loadProgress(int)"); page.loadFinished.connect(this, "loadFinished()"); } public void requestFinished(QNetworkReply reply) { reply.reset(); reply.open(OpenModeFlag.ReadOnly); reply.readyRead.connect(this, "ready()"); // never gets called System.out.println("bytes: " + reply.url().toString()); // writes out asset uri no problem System.out.println("bytes: " + reply.bytesToWrite()); // 0 System.out.println("At end: " + reply.atEnd()); // true System.out.println("Error: " + reply.errorString()); // "Unknown error" } public void loadProgress(int progress) { System.out.println("Loaded " + progress + "%"); } public void loadFinished() { System.out.println("Done"); } public void ready() { System.out.println("Ready"); } public void open(String url) { page.mainFrame().load(new QUrl(url)); } public static void main(String[] args) { QApplication.initialize(new String[] { }); Test t = new Test(); t.open("http://news.bbc.co.uk"); QApplication.exec(); } }

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• ExternalInterface

  - by Jesse

  Hey, so I'm having a bunch of trouble getting ExternalInterface to work, which is odd, because I use it somewhat often. I'm hoping it's something I just missed because I've been looking at it too long. The flash_ready function is correctly returning the objectID, and as far as I can tell, everything else is in order. Unfortunately, when I run it, I get an error (varying by browser) telling me that basically document.getElementById(<movename>).test() is not a valid method. Here's the code: javascript: function flash_ready(i){ document.getElementById(i).test('success!'); } Embed Html (Generated): <script type="text/javascript"> swfobject.embedSWF("/chainmaille/includes/media/flash/upload_image.swf", "/chainmaille/includes/media/flash/upload_image", "500", "50", "9.0.0","expressInstall.swf", {}, {allowScriptAccess:'always', wmode:'transparent'},{id:'uploader_flash',name:'uploader_flash'}); </script> <object type="application/x-shockwave-flash" id="uploader_flash" name="uploader_flash" data="/chainmaille/includes/media/flash/upload_image.swf" width="500" height="50"><param name="allowScriptAccess" value="always"><param name="wmode" value="transparent"></object> AS3 : package com.jesseditson.uploader { import flash.display.MovieClip; import flash.external.ExternalInterface; import flash.system.Security; public class UI extends MovieClip { // Initialization: public function UI() { Security.allowDomain('*'); ExternalInterface.addCallback("test", test); var jscommand:String = "flash_ready('"+ExternalInterface.objectID+"');"; var url:URLRequest = new URLRequest("javascript:" + jscommand + " void(0);"); navigateToURL(url, "_self"); } public function test(t){ trace(t); } } } Swfobject is being included via google code, and the flash embeds just fine, so that's not the problem. I've got a very similar setup working on another server, but can't seem to get it working on this one. It's a Hostgator shared server. Could it be the server's fault? Anybody see any obvious syntax problems? Thanks in advance!

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• Hibernate triggering constraint violations using orphanRemoval

  - by ptomli

  I'm having trouble with a JPA/Hibernate (3.5.3) setup, where I have an entity, an "Account" class, which has a list of child entities, "Contact" instances. I'm trying to be able to add/remove instances of Contact into a List<Contact> property of Account. Adding a new instance into the set and calling saveOrUpdate(account) persists everything lovely. If I then choose to remove the contact from the list and again call saveOrUpdate, the SQL Hibernate seems to produce involves setting the account_id column to null, which violates a database constraint. What am I doing wrong? The code below is clearly a simplified abstract but I think it covers the problem as I'm seeing the same results in different code, which really is about this simple. SQL: CREATE TABLE account ( INT account_id ); CREATE TABLE contact ( INT contact_id, INT account_id REFERENCES account (account_id) ); Java: @Entity class Account { @Id @Column public Long id; @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true) @JoinColumn(name = "account_id") public List<Contact> contacts; } @Entity class Contact { @Id @Column public Long id; @ManyToOne(optional = false) @JoinColumn(name = "account_id", nullable = false) public Account account; } Account account = new Account(); Contact contact = new Contact(); account.contacts.add(contact); saveOrUpdate(account); // some time later, like another servlet request.... account.contacts.remove(contact); saveOrUpdate(account); Result: UPDATE contact SET account_id = null WHERE contact_id = ? Edit #1: It might be that this is actually a bug http://opensource.atlassian.com/projects/hibernate/browse/HHH-5091

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• Multiple user roles in Ruby on Rails

  - by aguynamedloren

  I am building an inventory management application with four different user types: admin, employee, manufacturer, transporter. I haven't started coding yet, but this is what I'm thinking.. Manufacturers and transporters are related with has_many :through many-to-many association with products as follows: class Manufacturer < ActiveRecord::Base has_many :products has_many :transporters, :through => :products end class Product < ActiveRecord::Base belongs_to :manufacturer belongs_to :transporter end class Transporter < ActiveRecord::Base has_many :products has_many :manufacturers, :through => :products end All four user types will be able to login, but they will have different permissions and views, etc. I don't think I can put them in the same table (Users), however, because they will have different requirements, ie: vendors and manufacturers must have a billing address and contact info (through validations), but admins and employees should not have these fields. If possible, I would like to have a single login screen as opposed to 4 different screens. I'm not asking for the exact code to build this, but I'm having trouble determining the best way to make it happen. Any ideas would be greatly appreciated - thanks!

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• Loading and binding a serialized view model to a WPF window?

  - by generalt

  Hello all. I'm writing a one-window UI for a simple ETL tool. The UI consists of the window, the code behind for the window, a view model for the window, and the business logic. I wanted to provide functionality to the users to save the state of the UI because the content of about 10-12 text boxes will be reused between sessions, but are specific to the user. I figured I could serialize the view model, which contains all the data from the textboxes, and this works fine, but I'm having trouble loading the information in the serialized XML file back into the text boxes. Constructor of window: public ETLWindow() { InitializeComponent(); _viewModel = new ViewModel(); this.DataContext = _viewModel; _viewModel.State = Constants.STATE_IDLE; Loaded += new RoutedEventHandler(MainWindow_Loaded); } XAML: <TextBox x:Name="targetDirectory" IsReadOnly="true" Text="{Binding TargetDatabaseDirectory, UpdateSourceTrigger=PropertyChanged}"/> ViewModel corresponding property: private string _targetDatabaseDirectory; [XmlElement()] public string TargetDatabaseDirectory { get { return _targetDatabaseDirectory; } set { _targetDatabaseDirectory = value; OnPropertyChanged(DataUtilities.General.Utilities.GetPropertyName(() => new ViewModel().TargetDatabaseDirectory)); } Load event in code behind: private void loadState_Click(object sender, RoutedEventArgs e) { string statePath = this.getFilePath(); _viewModel = ViewModel.LoadModel(statePath); } As you can guess, the LoadModel method deserializes the serialized file on the user's drive. I couldn't find much on the web regarding this issue. I know this probably has something to do with my bindings. Is there some way to refresh on the bindings on the XAML after I deserialize the view model? Or perhaps refresh all properties on the view model? Or am I completely insane thinking any of this could be done? Thanks.

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• getting the list of all functions executed like call stack in asp.net

  - by sridhar

  Hi, I am having trouble with debugging one of the problems that I am having in our website. This is the problem. I have a webpage that contains the photo of an employee and information related to the employee. When the user logins to our website, we are storing the details of the employee in session. I am setting the image url for the photo of an employee as follows. imgEEPhoto.ImageUrl = imgPhoto.aspx?Company=XXXX&Empno=YYYY. Inside the page imgPhoto.aspx, I am checking if the session is alive for that user. when I login to the page that has the employee photo sometimes the photo is not displayed. It is because I am checking whether the session is alive inside the imgPhoto.aspx page. sometimes the session is alive and sometimes the session is not alive. It looks like there is some function that is setting the session to null asynchronously. I am not knowing how to track that function. so I am thinking that inside the imgPhoto.aspx page, if I can get the list of all functions that have been executed so far, I could track the function that is resetting the session. Is there a way to find this? If there is no another way to debug this problem, please let me know. Thanks, sridhar.

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• Manipulating jQuery to retrieve the onclick function of an item which lies directly below the curren

  - by Stevie Jenowski

  First off, I want to thank you for looking into my question as I really do appreciate your time. I've built a list of items using php by having a foreach loop cycle through an associative array printing the array data as parameters of an onclick function call and gives each item it cycles through an ID of $thecount. All items retrieved have the same parent div and calls the very same onclick function, only with 11 different parameters. My question is how do I go about calling the onClick("function();") of an item directly below the current focus, making it the new focus, only without a physical click? If this is confusing to you whatsoever, I'm essentially building a dynamic playlist, and I've already implemented the listener for when the player's current item has finished playing, Now I'm having trouble grasping how I'd go about having the next item in the list become the new focus while also calling it's specific onClick() function once the player returns that it has finished with the current file. All without any user interaction besides the initial play call. If it helps I'm using the most recent release of Longtails' JW Player and once again thank you very much for your time!

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• does actionscript addChild require a display object first

  - by touB

  I'm trying to move away from mxml to actionsctipt. I have a <s:Rect> that I've created and set its properties, but having trouble adding it. var aRect:Rect = new Rect(); //set properties like aRect.x, aRect.y, aRect.width, aRect.height //tried adding it various ways addChild(aRect); Application.addChild(aRect); Application.application.addChild(aRect); stage.addChild(aRect); But I keep getting the error 1067: Implicit coercion of a value of type spark.primitives:Rect to an unrelated type flash.display:DisplayObject Originally in the mxml, it was right inside <s:Application> not nested inside anything <s:Application> <s:Rect id="aRect" x="10" y="10" width="15%" height="15%"> //then fill code here, removed for readability </s:Rect> </s:Application> What's the deal, I thought actionscript would be nicer than mxml.

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• interval overlapping in tsql

  - by Nico

  hi folks, i need to get splited intervals and the number of overlapping intervals, eg basedata: interval A: startTime 08:00, endTime 12:00 interval B: startTime 09:00, endTime 12:00 interval C: startTime 12:00, endTime 16:00 interval D: startTime 13:00, endTime 14:00 now i have a separate interval from 10:00 to 15:00 and have to determine what intervals are intersected at first. result should be something like: 1: 10:00 - 12:00 ( intersecting with interval A ) 2: 10:00 - 12:00 ( intersecting with interval B ) 3: 12:00 - 15:00 ( intersecting with interval C ) 4: 13:00 - 14:00 ( intersecting with interval D ) this part works fine, the following causes the trouble: i need some kind of weighting for parallel intervals. this also means, that it can occur that an interval-intersection must be splitted n times, if it's ( partly ) intersected by another one. in the upper example the expecting result would be: 1: 10:00 - 12:00 -> weightage: 50% 2: 10:00 - 12:00 -> weightage: 50% 3.1: 12:00 - 13:00 -> weightage: 1oo% 3.2: 13:00 - 14:00 -> weightage: 50% 3.3: 14:00 - 15:00 -> weightage: 50% 4: 13:00 - 14:00 -< weightage: 100% the splitting of interval 3 is caused by the intersecting with interval 4 between 13:00 and 14:00. sql-server is ms-sql 2008. thanks for help in advance!

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• Using wildcards in prepared statement - MySQLi

  - by Michael Irwin

  Hi! I'm trying to run the following query, and I'm having trouble with the wildcard. function getStudents() { global $db; $users = array(); $query = $db->prepare("SELECT id, adminRights FROM users WHERE classes LIKE ? && adminRights='student'"); $query->bind_param('s', '%' . $this->className . '%'); $query->execute(); $query->bind_result($uid, $adminRights); while ($query->fetch()) { if (isset($adminRights[$this->className]) && $adminRights[$this->className] == 'student') $users[] = $uid; } $query->close(); return $users; } I'm getting an error that states: Cannot pass parameter 2 by reference. The reason I need to use the wildcard is because the column's data contains serialized arrays. I guess, if there's an easier way to handle this, what could I do? Thanks in advance!

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• Modeling related objects and their templates

  - by Duddle

  Hello everybody! I am having trouble correctly modeling related objects that can use templates. This is not homework, but part of a small project in the university. In this application the user can add several elements, which can either be passive or active. Each concrete element has different attributes, these must be set by the user. See diagram 1: Since the user will create many elements, we want there to be templates for each type of element, so some of the attributes are filled in automatically. See diagram 2: In my opinion, this is a bad design. For example, to get all possible templates for a PassiveElementA-object, there has to be a list/set somewhere that only holds PassiveElementATemplate-objects. There has to be a separate list for each subclass of Element. So if you wanted to add a new PassiveElement-child, you also have to edit the class which holds all these separate lists. I cannot figure out a good way to solve this problem. Since the concrete classes (i.e. PassiveElementA, ..., PassiveElementZ) have so many different attributes, many of the design patterns I know do not work. Thanks in advance for any hints, and sorry for my bad English.

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• Java Swing Table questions

  - by Dalton Conley

  Hey guys, working on an event calendar. I'm having some trouble getting my column heads to display.. here is the code private JTable calendarTable; private DefaultTableModel calendarTableModel; final private String [] days = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}; ////////////////////////////////////////////////////////////////////// /* Setup the actual calendar table */ calendarTableModel = new DefaultTableModel() { public boolean isCellEditable(int row, int col){ return false; } }; // setup columns for(int i = 0; i < 7; i++) calendarTableModel.addColumn(days[i]); calendarTable = new JTable(calendarTableModel); calendarTable.getTableHeader().setResizingAllowed(false); calendarTable.getTableHeader().setReorderingAllowed(false); calendarTable.setColumnSelectionAllowed(true); calendarTable.setRowSelectionAllowed(true); calendarTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); calendarTable.setRowHeight(105); calendarTableModel.setColumnCount(7); calendarTableModel.setRowCount(6); Also, Im sort of new with tables.. how can I make the rowHeight split between the max size of the table?

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• How to target multiple versions of .NET Framework from MSBuild?

  - by McKAMEY

  I am improving the builds for an open source project which currently supports .NET Framework v2.0, v3.5, and now v4.0. Up until now, I've restricted myself to v2.0 to ensure compatibility, but with VS2010 I am interested in having real targeted builds. I'm looking for some guidance on how to edit the MSBuild csproj/sln to be able to cleanly produce builds for each target. I'm willing to have complexity in the csproj and in a batch file to control the build. My goal is to be able to have a command line script that could produce the builds without needing Visual Studio installed, but only the necessary .NET Framework(s). Ideally, I'd like to minimize dependencies on additional software. I notice that a lot of people use NAnt (e.g. Ninject builds many targets with NAnt) but I'm unsure if this is necessary or if they are just more familiar with it. I'm pretty sure this can be done but am having trouble finding a definitive guide on setting it up and best practices. Bonus: my next step after getting this set up will be to better support Mono Framework. Any help on doing this same thing for Mono would be much appreciated.

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• C# Help with a basic pedagogic example of a BackGroundWorker process populating a DataGridView

  - by Roger

  Scenario: I have a windows form that holds a DataGridWiew with 3 pre-defined columns. I have 3 variables declared outside the function and assigned to inside the function. I have a function that enumerates stuff and puts it in the 3 columns, line by line: string VARIABLE1; string VARIABLE2; string VARIABLE3; private void FunctionEnumerateStuff() { foreach (StuffObject STUFF in StuffCollection) { VARIABLE1 = STUFF.SubStuff1.ToString(); VARIABLE2 = STUFF.SubStuff2.ToString(); VARIABLE3 = STUFF.SubStuff3.ToString(); DatagridWiew1.Rows.Add(VALUE1, VALUE2, VALUE3); } } What I want to do, is to execute this function from a BackGroundWorker process, so that the GUI of the application will be smooth and responsive. I have read up on backgroundworkers but I am having trouble relating, because all examples seems to be of entirely different scenarios and most of them are overwelmingly complex. San some helpful pedagogic soul help me and others with a very basic example of how to get this to work in the simplest way possible. Thanks.

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• WCF Callbacks often break

  - by cdecker

  I'm having quite some trouble with the WCF Callback mechanism. They sometimes work but most of the time they don't. I have a really simple Interface for the callbacks to implement: public interface IClientCallback { [OperationContract] void Log(string content); } I then implmenent that interface with a class on the client: [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)] [ServiceContract] internal sealed class ClientCallback : IClientCallback { public void Log(String content){ Console.Write(content); } } And on the client I finally connect to the server: NetTcpBinding tcpbinding = new NetTcpBinding(SecurityMode.Transport); EndpointAddress endpoint = new EndpointAddress("net.tcp://127.0.0.1:1337"); ClientCallback callback= new ClientCallback(); DuplexChannelFactory<IServer> factory = new DuplexChannelFactory<IServer>(callback,tcpbinding, endpoint); factory.Open(); _connection = factory.CreateChannel(); ((ICommunicationObject)_connection).Faulted += new EventHandler(RecreateChannel); try { ((ICommunicationObject)_connection).Open(); } catch (CommunicationException ce) { Console.Write(ce.ToString()); } To invoke the callback I use the following: OperationContext.Current.GetCallbackChannel().Log("Hello World!"); But it just hangs there, and after a while the client complains about timeouts. Is there a simple solution as to why?

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• Inconsistency in modified/created/accessed time on mac

  - by Seth Johnson

  I'm having trouble using os.utime to correctly set the modification time on the mac (Mac OS X 10.6.2, running Python 2.6.1 from /usr/bin/python). It's not consistent with the touch utility, and it's not consistent with the properties displayed in the Finder's "get info" window. Consider the following command sequence. The 'created' and 'modified' times in the plain text refer to the "get info" window attributes. As a reminder, os.utime takes arguments (filename, (atime, mtime)). >>> import os >>> open('tempfile','w').close() 'created' and 'modified' are both the current time. >>> os.utime('tempfile', (1000000000, 1500000000) ) 'created' is the current time, 'modified' is July 13, 2017. >>> os.utime('tempfile', (1000000000, 1000000000) ) 'created' and 'modified' are both September 8, 2001. >>> os.path.getmtime('tempfile') 1000000000.0 >>> os.path.getctime('tempfile') 1269021939.0 >>> os.path.getatime('tempfile') 1269021951.0 ...but the os.path.get?time and os.stat don't reflect it. >>> os.utime('tempfile', (1500000000, 1000000000) ) 'created' and 'modified' are still both September 8, 2001. >>> os.utime('tempfile', (1500000000, 1500000000) ) 'created' is September 8, 2001, 'modified' is July 13, 2017. I'm not sure if this is a Python problem or a Mac stat problem. When I exit the Python shell and run touch -a -t 200011221234 tempfile neither the modification nor the creation times are changed, as expected. Then I run touch -m -t 200011221234 tempfile and both 'created' and 'modified' times are changed. Does anyone have any idea what's going on? How do I change the modification and creation times consistently on the mac? (Yes, I am aware that on Unixy systems there is no "creation time.")

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• Creating a DataTable by filtering another DataTable

  - by Jeff Dege

  I'm working on a system that currently has a fairly complicated function that returns a DataTable, which it then binds to a GUI control on a ASP.NET WebForm. My problem is that I need to filter the data returned - some of the data that is being returned should not be displayed to the user. I'm aware of DataTable.select(), but that's not really what I need. First, it returns an array of DataRows, and I need a DataTable, so I can databind it to the GUI control. But more importantly, the filtering I need to do isn't something that can be easily put into a simple expression. I have an array of the elements which I do not want displayed, and I need to compare each element from the DataTable against that array. What I could do, of course, is to create a new DataTable, reading everything out of the original, adding to the new what is appropriate, then databinding the new to the GUI control. But that just seems wrong, somehow. In this case, the number of elements in the original DataTable aren't likely to be enough that copying them all in memory is going to cause too much trouble, but I'm wondering if there is another way. Does the .NET DataTable have functionality that would allow me to filter via a callback function?

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• Why avoid increment ("++") and decrement ("--") operators in JavaScript?

  - by artlung

  I'm a big fan of Douglas Crockford's writing on JavaScript, particularly his book JavaScript: The Good Parts. It's made me a better JavaScript programmer and a better programmer in general. One of his tips for his jslint tool is this : ++ and -- The ++ (increment) and -- (decrement) operators have been known to contribute to bad code by encouraging excessive trickiness. They are second only to faulty architecture in enabling to viruses and other security menaces. There is a plusplus option that prohibits the use of these operators. This has always struck my gut as "yes, that makes sense," but has annoyed me when I've needed a looping condition and can't figure out a better way to control the loop than a while( a < 10 )do { a++ } or for (var i=0;i<10;i++) { } and use jslint. It's challenged me to write it differently. I also know in the distant past using things, in say PHP like $foo[$bar++] has gotten me in trouble with off-by-one errors. Are there C-like languages or other languages with similarities that that lack the "++" and "--" syntax or handle it differently? Are there other rationales for avoiding "++" and "--" that I might be missing? UPDATE -- April 9, 2010: In the video Crockford on JavaScript -- Part 5: The End of All Things, Douglas Crockford addresses the ++ issue more directly and with more detail. It appears at 1:09:00 in the timeline. Worth a watch.

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• Building a many-to-many db schema using only an unpredictable number of foreign keys

  - by user1449855

  Good afternoon (at least around here), I have a many-to-many relationship schema that I'm having trouble building. The main problem is that I'm only working with primary and foreign keys (no varchars or enums to simplify things) and the number of many-to-many relationships is not predictable and can increase at any time. I looked around at various questions and couldn't find something that directly addressed this issue. I split the problem in half, so I now have two one-to-many schemas. One is solved but the other is giving me fits. Let's assume table FOO is a standard, boring table that has a simple primary key. It's the one in the one-to-many relationship. Table BAR can relate to multiple keys of FOO. The number of related keys is not known beforehand. An example: From a query FOO returns ids 3, 4, 5. BAR needs a unique key that relates to 3, 4, 5 (though there could be any number of ids returned) The usual join table does not work: Table FOO_BAR primary_key | foo_id | bar_id | Since FOO returns 3 unique keys and here bar_id has a one-to-one relationship with foo_id. Having two join tables does not seem to work either, as it still can't map foo_ids 3, 4, 5 to a single bar_id. Table FOO_TO_BAR primary_key | foo_id | bar_to_foo_id | Table BAR_TO_FOO primary_key | foo_to_bar_id | bar_id | What am I doing wrong? Am I making things more complicated than they are? How should I approach the problem? Thanks a lot for the help.

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• Problems referencing build output from TFS Build and Visual Studio

  - by pmdarrow

  Here's what I'm trying to do: I have two solutions - one for my main application and its associated projects and another for my database (VS .dbproj) and its associated projects. What I'd like to do is include the output from the database project (a .dbschema and some SQL scripts) in my WiX installer (which exists in the main application solution.) This involves having TFS build the DB solution immediately before the main application solution. I've got that part working properly, but I'm having trouble referencing the output of the DB solution from my installer. I'm using relative paths to reference the DB project output in my WiX installer (e.g. <?define DBProjectOutputDir = "..\..\MyDatabaseSolution\MyDatabaseProject\sql\"?>) which works fine locally, but fails when building via TFS build. This is because TFS Build apparently changes the output dir of each project to one common location. Instead of the path to my database project being ..\..\MyDatabaseSolution\MyDatabaseProject\sql\ like it is when building locally, it gets set to something like ..\..\..\Binaries\Release\. How can I get around this and have a consistent output location to reference from my installer project? I'm using TFS 2005 and VS 2008.

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