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  • How can I bind a List as ItemSource to ListView in XAML?

    - by Jonas
    I'm learning WPF and would like to have a collection similar to a LinkedList, to where I can add and remove strings. And I want to have a ListView that listen to that collection with databinding. How can I do bind a simple list collection to a ListView in XAML? My idea (not working) is something like this: <Window x:Class="TestApp.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <Window.Resources> <LinkedList x:Key="myList"></LinkedList> //Wrong <Window.Resources> <Grid> <ListView Height="100" HorizontalAlignment="Left" Margin="88,134,0,0" Name="listView1" VerticalAlignment="Top" Width="120" ItemsSource="{Binding Source={StaticResource myList}}"/> //Wrong </Grid> </Window> All my code (updated version, not working): <Window x:Class="TestApp.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <Grid> <TextBox Height="23" HorizontalAlignment="Left" Margin="12,12,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" /> <Button Content="Button" Height="23" HorizontalAlignment="Right" Margin="0,12,290,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" /> <ListView Height="100" HorizontalAlignment="Left" Margin="88,134,0,0" Name="listView1" VerticalAlignment="Top" Width="120" ItemsSource="{Binding myList}"/> </Grid> </Window> C#-code: namespace TestApp { public partial class MainWindow : Window { ObservableCollection<string> myList = new ObservableCollection<string>(); public MainWindow() { InitializeComponent(); myList.Add("first string"); } private void button1_Click(object sender, RoutedEventArgs e) { myList.Add(textBox1.Text); textBox1.Text = myList.Count+"st"; } } }

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  • Android - Parsing XML with XPath

    - by Ruben Deig Ramos
    First of all, thanks to all the people who's going to spend a little time on this question. Second, sorry for my english (not my first language! :D). Well, here is my problem. I'm learning Android and I'm making an app which uses a XML file to store some info. I have no problem creating the file, but trying to read de XML tags with XPath (DOM, XMLPullParser, etc. only gave me problems) I've been able to read, at least, the first one. Let's see the code. Here is the XML file the app generates: <dispositivo> <id>111</id> <nombre>Name</nombre> <intervalo>300</intervalo> </dispositivo> And here is the function which reads the XML file: private void leerXML() { try { XPathFactory factory=XPathFactory.newInstance(); XPath xPath=factory.newXPath(); // Introducimos XML en memoria File xmlDocument = new File("/data/data/com.example.gps/files/devloc_cfg.xml"); InputSource inputSource = new InputSource(new FileInputStream(xmlDocument)); // Definimos expresiones para encontrar valor. XPathExpression tag_id = xPath.compile("/dispositivo/id"); String valor_id = tag_id.evaluate(inputSource); id=valor_id; XPathExpression tag_nombre = xPath.compile("/dispositivo/nombre"); String valor_nombre = tag_nombre.evaluate(inputSource); nombre=valor_nombre; } catch (Exception e) { e.printStackTrace(); } } The app gets correctly the id value and shows it on the screen ("id" and "nombre" variables are assigned to a TextView each one), but the "nombre" is not working. What should I change? :) Thanks for all your time and help. This site is quite helpful! PD: I've been searching for a response on the whole site but didn't found any.

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  • horizontal uiview's controls unresponsive.. or how to foul up a view hierarchy

    - by Oldmicah
    Hello all, I'm working on an app that has two sections, a config section and a results section. My config section needs to be 2 separate views (horizontal and vert, and yes, I can hear the intake of breath from here), with one rotatable view for the results. b/c of layout restraints and a lot of pain around rotation, I'm not using a navigation controller. I've been experiencing the joys of rotation experimentation and have settled upon keeping my views contained as subviews of my view controller. i.e. view controller.view.subviews = configH, configV, and results. I then use the controller.view bringSubviewToFront to bring the either the configH, configV, or the result view to the front. Rotation works-queue(humor intended) the angelic choirs... almost. What's happening is that my configV button's are responsive, but when the device (or simulator) is rotated, my configH controls are not. (configV is the second subview added, but the first one to be brought to the front because app comes up in portrait mode) The controls on the results view also work. Plan B was to assign the controller.view to configH, configV, or results. All of my controls now work, but rotation is now fouled up. Question 1: Is there a better way to do this? (a horizontal and vertical config view and a rotatable results view) Question 2: Does the above suggest a design issue, or is it more likely that my addled brain is just missing something in my own code. (nothing from the peanut gallery please) many thanks!

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  • Cryptic Erlang Errors

    - by Jim
    Okay so I started learning erlang recently but am baffled by the errors it keeps returning. I made a bunch of changes but I keep getting errors. The syntax is correct as far as I can tell but clearly I'm doing something wrong. Have a look... -module(pidprint). -export([start/0]). dostuff([]) - receive begin - io:format("~p~n", [This is a Success]) end. sender([N]) - N ! begin, io:format("~p~n", [N]). start() - StuffPid = spawn(pidprint, dostuff, []), spawn(pidprint, sender, [StuffPid]). Basically I want to compile the script, call start, spawn the "dostuff" process, pass its process identifier to the "sender" process, which then prints it out. Finally I want to send a the atom "begin" to the "dostuff" process using the process identifier initially passed into sender when I spawned it. The errors I keep getting occur when I try to use c() to compile the script. Here they are.. ./pidprint.erl:6: syntax error before: '-' ./pidprint.erl:11: syntax error before: ',' What am I doing wrong?

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  • Dynamically disable custom (VBA) Excel context menu buttons?

    - by Lopsided
    The Scenario Hi guys, I am about to add a few custom controls to the cell context menu in my Excel workbook using the instructions found on this MSDN page. The only problem I am having is that I need the items to only be enabled for a specific column/range of cells. I've looked around, and I've been unable to find any steps for this--there are some for VSTO development (written in C#), but that is not what I need. I plan to write this using the VBA IDE built into Office, and perhaps a bit of XML using the Custom UI Editor. The Question So basically, I'm looking for a way to run a function at the time the context menu is called (i.e., upon right-click) that validates the selection to make sure it is in the appropriate column. If it isn't, I would like my custom buttons to be greyed out. P.S. Please don't think I am asking you to write my code. Creating these buttons should be very simple, as I have created many before (albeit they were all Ribbon items), and I hope it is okay to ask for some quick assistance on this very specific issue. Thank you in advance!

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  • Wnat is the preferred method of building extremely lightweight business object / DAL now that I have

    - by Seth Spearman
    Hello, I have completed a simple database for a project. Only 6tables. Of the 6, one is a "lookup" table. There is one "master" table that is the driver for the system. It is referenced as a foreign key by the other four tables. Give that this step is completed. What is the FASTEST, EASIEST way to create POCOs/BizObjects that can load load the data and the child data. Here are my CAVEATS. *I don't want to spend more than 30-60 minutes learning how? *There is very little biz logic needed in the POCOs. They will pretty much load data. Don't even really need to write back data. *I already know CSLA (up to version 3) but I feel that is overkill for this little project. *Nevertheless, I would love it if it ROOT objects could have collection classes that contain the CHILD objects as in CSLA...but again, without using CSLA. *Please give the answer for .NET 35 but also if I was restricted to only use .NET 20. *Ideally I could just point a tool at the database and the POCOs would be genn'ed. *FREE Just curious what you guys use for this kind of scenario. I understand that this question is subjective but I want to hear a variety of answers. Seth

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  • jQuery: show an element from select drop down, hide it when other option selected

    - by Ricardo Zea
    I've tried looking around and there are similar problems, but mine is way more simple, but yet, I can't find a solution within these forums. While learning jQuery, I'm trying to show a DIV when an item/option from a select drop down is selected, and hide that same DIV when any other option in the select drop down is selected. select HTML: <select name="source" id="source"> <option value="null" selected="selected">&mdash;Select&mdash;</option> <option value="s1">Source 1</option> <option value="s2">Source 2</option> <option value="sother">Other</option> </select> DIV I need to show when 'Other' is selected: <div id="specify-source">Other source here...</div> When any other option in the select menu is selected, the above DIV shouldn't be visible. I've tried this jQuery but of course it doesn't work properly: $(function() { $.viewMap = { 'sother' : $('#specify-source') }; $('#source').change(function() { // hide all $.each($.viewMap, function() { this.hide(); }); // show current $.viewMap[$(this).val()].show(); }); }); Any help you can give me, I'd greatly appreciate it. Thanks,

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  • Is XSLT worth investing time in and are there any actual alternatives?

    - by Keeno
    I realize this has been a few other questions on this topic, and people are saying use your language of choice to manipulate the XML etc etc however, not quite fit my question exactly. Firstly, the scope of the project: We want to develop platform independent e-learning, currently, its a bunch of HTML pages but as they grow and develop they become hard to maintain. The idea: Generate up an XML file + Schema, then produce some XSLT files that process the XML into the eLearning modiles. XML to HTML via XSLT. Why: We would like the flexibilty to be able to easy reformat the content (I realize CSS is a viable alternative here) If we decide to alter the pages layout or functionality in anyway, im guessing altering the "shared" XSLT files would be easier than updating the HTML files. So far, we have about 30 modules, with up to 10-30 pages each Depending on some "parameters" we could output drastically different page layouts/structures, above and beyond what CSS can do Now, all this has to be platform independent, and to be able to run "offline" i.e. without a server powering the HTML Negatives I've read so far for XSLT: Overhead? Not exactly sure why...is it the compute power need to convert to HTML? Difficult to learn Better alternatives Now, what I would like to know exactly is: are there actually any viable alternatives for this "offline"? Am I going about it in the correct manner, do you guys have any advice or alternatives. Thanks!

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  • App crashes every second time a tableview row is selected in navigation controller setup

    - by Thaurin
    Disclaimer first: I'm pretty new to Objective-C and the retain model. I've been developing in a garbage collected .NET environment for the last five years, so I've been spoiled. I'm still learning. I'm having my iPhone app crash with EXC_BAD_ACCESS. It happens in a navigtation controller/tableview setup. When I select a row the first time, no problems. It switches in the child controller without problems. I go back and select the same row again. Program then proceeds to crash. Every other row works fine, but every second time a row is accessed, it's a crash. I've pinpointed the location where this happens. The child controller (which is a class that I reuse for every row of the same type) that's being switched into has an array of NSString's representing the rows that will be displayed. I set it before pushing the child viewcontroller. It's there where this apparently happens. I'm having a hard time debugging this problem, still wrestling with xcode and all. I fear there may be some vital information missing here, but maybe there is something you recognize here.

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  • Resources and techniques/methods for SCJP preparation ?

    - by BenoitParis
    I am passing the SCJP 6 exam in a month. I have the "SCJP Sun Certified Programmer for Java 6 Exam 310-065" book. It seems great for the exam. But I want your advice on this. Getting the closest possible to 100% would be great. I have found a site that answered some of the questions you ask yourself when you go trough the book. Here is it : http://www.janeg.ca/java2.html As you can see it was written for Java 2 :/ I have written another specific question here on StackOverflow about the usefulness of JVM specification and Java compiler code for the SCJP. Will Update the results here. Here it is. Please share the resources you used in preparing the exam. Please also specify any resources that you think might help. Any type of resource is welcome: books, code, specs, sites, wikies, papers, online tests, grandmas... Please also share on any method/technique that helped you prepare the exam. Please also comment on the return you got from the resource and the method (for the learning process and for points in the exam) I'll begin: Book : "SCJP Sun Certified Programmer for Java 6 Exam 310-065". Seems like the official book for the preparation. Technique : Writing code in a text editor and compiling it with javac to test a question. NO IDEs! It helps you get a a straight answer to a question you have. It helps you pay attention to every word in the code (and this is very important in the SCJP) EDIT: Added dimension: Are there good, up-to-date online tests?

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  • using the :sass filter with :css

    - by corroded
    We are currently making a widget that requires some default declared styles along with it(widget html is included by javasacript, along with the default css in style tags) but the problem is i can't "chain" haml filters. What I'm trying to do is to add an internal stylesheet along with the widget like so: <style type="text/css"> p {color: #f00;} </style> <div id="widget-goes-here"> <p>etc</p> </div> We are using haml so I tried doing it with the sass filter: :sass p :color #f00 #widget-goes-here %p etc sadly, it just generated a div with a p plus the generated css code literally on top: p {color: #f00;} paragraph here I then tried using the :css filter of haml to enclose the thing in style tags(theoretically it should then turn the paragraph text color to red): :css :sass p :color #f00 #widget-goes-here %p etc But this also failed, it did generated style tags but then it just enclosed the words :sass p :color #f00 in it(it didn't parse the sass code) We did change it to :css p {color: #f00} and it worked out fine, but I still plan on doing the styling in sass(instead of plain old css) is there a way to do this?

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  • Shrinking the transaction log of a mirrored SQL Server 2005 database

    - by Peter Di Cecco
    I've been looking all over the internet and I can't find an acceptable solution to my problem, I'm wondering if there even is a solution without a compromise... I'm not a DBA, but I'm a one man team working on a huge web site with no extra funding for extra bodies, so I'm doing the best I can. Our backup plan sucks, and I'm having a really hard time improving it. Currently, there are two servers running SQL Server 2005. I have a mirrored database (no witness) that seems to be working well. I do a full backup at noon and at midnight. These get backed up to tape by our service provider nightly, and I burn the backup files to dvd weekly to keep old records on hand. Eventually I'd like to switch to log shipping, since mirroring seems kinda pointless without a witness server. The issue is that the transaction log is growing non-stop. From the research I've done, it seems that I can't truncate a log file of a mirrored database. So how do I stop the file from growing!? Based on this web page, I tried this: USE dbname GO CHECKPOINT GO BACKUP LOG dbname TO DISK='NULL' WITH NOFORMAT, INIT, NAME = N'dbnameLog Backup', SKIP, NOREWIND, NOUNLOAD GO DBCC SHRINKFILE('dbname_Log', 2048) GO But that didn't work. Everything else I've found says I need to disable the mirror before running the backup log command in order for it to work. My Question (TL;DR) How can I shrink my transaction log file without disabling the mirror?

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  • Do database engines other than SQL Server behave this way?

    - by Yishai
    I have a stored procedure that goes something like this (pseudo code) storedprocedure param1, param2, param3, param4 begin if (param4 = 'Y') begin select * from SOME_VIEW order by somecolumn end else if (param1 is null) begin select * from SOME_VIEW where (param2 is null or param2 = SOME_VIEW.Somecolumn2) and (param3 is null or param3 = SOME_VIEW.SomeColumn3) order by somecolumn end else select somethingcompletelydifferent end All ran well for a long time. Suddenly, the query started running forever if param4 was 'Y'. Changing the code to this: storedprocedure param1, param2, param3, param4 begin if (param4 = 'Y') begin set param2 = null set param3 = null end if (param1 is null) begin select * from SOME_VIEW where (param2 is null or param2 = SOME_VIEW.Somecolumn2) and (param3 is null or param3 = SOME_VIEW.SomeColumn3) order by somecolumn end else select somethingcompletelydifferent And it runs again within expected parameters (15 seconds or so for 40,000+ records). This is with SQL Server 2005. The gist of my question is this particular "feature" specific to SQL Server, or is this a common feature among RDBMS' in general that: Queries that ran fine for two years just stop working as the data grows. The "new" execution plan destroys the ability of the database server to execute the query even though a logically equivalent alternative runs just fine? This may seem like a rant against SQL Server, and I suppose to some degree it is, but I really do want to know if others experience this kind of reality with Oracle, DB2 or any other RDBMS. Although I have some experience with others, I have only seen this kind of volume and complexity on SQL Server, so I'm curious if others with large complex databases have similar experience in other products.

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  • CodeIgniter and SimpleTest -- How to make my first test?

    - by Smandoli
    I'm used to web development using LAMP, PHP5, MySQL plus NetBeans with Xdebug. Now I want to improve my development, by learning how to use (A) proper testing and (B) a framework. So I have set up CodeIgniter, SimpleTest and the easy Xdebug add-in for Firefox. This is great fun because maroonbytes provided me with clear instructions and a configured setup ready for download. I am standing on the shoulders of giants, and very grateful. I've used SimpleTest a bit in the past. Here is a the kind of thing I wrote: <?php require_once('../simpletest/unit_tester.php'); require_once('../simpletest/reporter.php'); class TestOfMysqlTransaction extends UnitTestCase { function testDB_ViewTable() { $this->assertEqual(1,1); // a pseudo-test } } $test = new TestOfMysqlTransaction(); $test->run(new HtmlReporter()) ?> So I hope I know what a test looks like. What I can't figure out is where and how to put a test in my new setup. I don't see any sample tests in the maroonbytes package, and Google so far has led me to posts that assume unit testing is already functionally available. What do I do?

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  • javascript split() array contains

    - by Mahesha999
    While learning JavaScript, I did not get why the output when we print the array returned of the Sting.split() method (with regular expression as an argument) is as explained below. var colorString = "red,blue,green,yellow"; var colors = colorString.split(/[^\,]+/); document.write(colors); //this print 7 times comma: ,,,,,,, However when I print individual element of the array colors, it prints an empty string, three commas and an empty string: document.write(colors[0]); //empty string document.write(colors[1]); //, document.write(colors[2]); //, document.write(colors[3]); //, document.write(colors[4]); //empty string document.write(colors[5]); //undefined document.write(colors[6]); //undefined Then, why printing the array directly gives seven commas. Though I think its correct to have three commas in the second output, I did not get why there is a starting (at index 0) and ending empty string (at index 4). Please explain I am screwed up here.

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  • python crc32 woes

    - by lazyr
    I'm writing a python program to extract data from the middle of a 6 GB bz2 file. A bzip2 file is made up of independently decryptable blocks of data, so I only need to find a block (they are delimited by magic bits), then create a temporary one-block bzip2 file from it in memory, and finally pass that to the bz2.decompress function. Easy, no? The bzip2 format has a crc32 checksum for the file at the end. No problem, binascii.crc32 to the rescue. But wait. The data to be checksummed does not necessarily end on a byte boundary, and the crc32 function operates on a whole number of bytes. My plan: use the binascii.crc32 function on all but the last byte, and then a function of my own to update the computed crc with the last 1-7 bits. But hours of coding and testing has left me bewildered, and my puzzlement can be boiled down to this question: how come crc32("\x00") is not 0x00000000? Shouldn't it be, according to the wikipedia article? You start with 0b00000000 and pad with 32 0's, then do polynomial division with 0x04C11DB7 until there are no ones left in the first 8 bits, which is immediately. Your last 32 bits is the checksum, and how can that not be all zeroes? I've searched google for answers and looked at the code of several crc32 implementations without finding any clue to why this is so.

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  • Why initialize an object to empty

    - by ProgEnthu
    I am learning windows programming with the help of MSDN.Why would somebody initialize an object like the following? WNDCLASS wc = { }; Will this zero all the memory of the object? Whole source code is following: #ifndef UNICODE #define UNICODE #endif #include <windows.h> LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam); int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow) { // Register the window class. const wchar_t CLASS_NAME[] = L"Sample Window Class"; WNDCLASS wc = { }; wc.lpfnWndProc = WindowProc; wc.hInstance = hInstance; wc.lpszClassName = CLASS_NAME; RegisterClass(&wc); // Create the window. HWND hwnd = CreateWindowEx( 0, // Optional window styles. CLASS_NAME, // Window class L"Learn to Program Windows", // Window text WS_OVERLAPPEDWINDOW, // Window style // Size and position CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, // Parent window NULL, // Menu hInstance, // Instance handle NULL // Additional application data ); if (hwnd == NULL) { return 0; } ShowWindow(hwnd, nCmdShow); // Run the message loop. MSG msg = { }; while (GetMessage(&msg, NULL, 0, 0)) { TranslateMessage(&msg); DispatchMessage(&msg); } return 0; } LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) { switch (uMsg) { case WM_DESTROY: PostQuitMessage(0); return 0; case WM_PAINT: { PAINTSTRUCT ps; HDC hdc = BeginPaint(hwnd, &ps); FillRect(hdc, &ps.rcPaint, (HBRUSH) (COLOR_WINDOW+1)); EndPaint(hwnd, &ps); } return 0; } return DefWindowProc(hwnd, uMsg, wParam, lParam); }

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  • PHP file upload issue

    - by Varun
    I am working on a PHP based, ticket management system. While creating a ticket, one can upload an attachment. I want to put a limit (say 10 MB) per file upload. To implement this I plan the following- 1. In php.ini set post_max_size = 10M 2.In PHP script which receives the POST- Since the file is larger than post_max_size, $_FILES[] will be empty. But I can still check the content-length header and discard the upload, if size more than 10M. While testing this I tried uploading a file of 1 GB and analysed the http traffic and this is what I found. - the entire 1 GB data is first uploaded to a to the server temporarily and discarded once the http request completes. Though I couldn't exactly find out where the file was getting saved(as it was not there in the temporary directory in the server.), but my http traffic analyzer showed that the browser did send 1 GB data to the server. - the PHP script execution started only after completion of the http request(i.e after uploading the entire 1 GB) Now I have 2 concerns: a) People may exploit my server bandwidth by trying to upload large file, which I will have to discard anyways. b) Even worse, if someone starts uploading a huge file (say 100 GB), entire 100 GB data is first uploaded to the server temporarily, that means for that period, it will consume that much of memory on my server. What's the common solution for this. Am I missing something here?

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  • CIE XYZ colorspace: do I have RGBA or XYZA?

    - by Tronic
    I plan to write a painting program based on linear combinations of xy plane points (0,1), (1,0) and (0,0). Such system works identically to RGB, except that the primaries are not within the gamut but at the corners of a triangle that encloses the entire gamut. I have seen the three points being referred to as X, Y and Z (upper case) somewhere, but I cannot find the page anymore (I marked them to the picture myself). My pixel format stores the intensity of each of those three components the same way as RGB does, together with alpha value. This allows using pretty much any image manipulation operation designed for RGBA without modifying the code. What is my format called? Is it XYZA, RGBA or something else? Google doesn't seem to know of XYZA. RGBA will get confused with sRGB + alpha (which I also need to use in the same program). Notice that the primaries X, Y and Z and their intensities have little to do with the x, y and z coordinates (lower case) that are more commonly used.

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  • sybase - values from one table that aren't on another, on opposite ends of a 3-table join

    - by Lazy Bob
    Hypothetical situation: I work for a custom sign-making company, and some of our clients have submitted more sign designs than they're currently using. I want to know what signs have never been used. 3 tables involved: table A - signs for a company sign_pk(unique) | company_pk | sign_description 1 --------------------1 ---------------- small 2 --------------------1 ---------------- large 3 --------------------2 ---------------- medium 4 --------------------2 ---------------- jumbo 5 --------------------3 ---------------- banner table B - company locations company_pk | company_location(unique) 1 ------|------ 987 1 ------|------ 876 2 ------|------ 456 2 ------|------ 123 table C - signs at locations (it's a bit of a stretch, but each row can have 2 signs, and it's a one to many relationship from company location to signs at locations) company_location | front_sign | back_sign 987 ------------ 1 ------------ 2 987 ------------ 2 ------------ 1 876 ------------ 2 ------------ 1 456 ------------ 3 ------------ 4 123 ------------ 4 ------------ 3 So, a.company_pk = b.company_pk and b.company_location = c.company_location. What I want to try and find is how to query and get back that sign_pk 5 isn't at any location. Querying each sign_pk against all of the front_sign and back_sign values is a little impractical, since all the tables have millions of rows. Table a is indexed on sign_pk and company_pk, table b on both fields, and table c only on company locations. The way I'm trying to write it is along the lines of "each sign belongs to a company, so find the signs that are not the front or back sign at any of the locations that belong to the company tied to that sign." My original plan was: Select a.sign_pk from a, b, c where a.company_pk = b.company_pk and b.company_location = c.company_location and a.sign_pk *= c.front_sign group by a.sign_pk having count(c.front_sign) = 0 just to do the front sign, and then repeat for the back, but that won't run because c is an inner member of an outer join, and also in an inner join. This whole thing is fairly convoluted, but if anyone can make sense of it, I'll be your best friend.

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  • My QFileSystemModel doesn't work as expected in PyQt

    - by Skilldrick
    I'm learning the Qt Model/View architecture at the moment, and I've found something that doesn't work as I'd expect it to. I've got the following code (adapted from Qt Model Classes): from PyQt4 import QtCore, QtGui model = QtGui.QFileSystemModel() parentIndex = model.index(QtCore.QDir.currentPath()) print model.isDir(parentIndex) #prints True print model.data(parentIndex).toString() #prints name of current directory childIndex = model.index(0, 0, parentIndex) print model.data(childIndex).toString() rows = model.rowCount(parentIndex) print rows #prints 0 (even though the current directory has directory and file children) The question: Is this a problem with PyQt, have I just done something wrong, or am I completely misunderstanding QFileSystemModel? According to the documentation, model.rowCount(parentIndex) should return the number of children in the current directory. The QFileSystemModel docs say that it needs an instance of a Gui application, so I've also placed the above code in a QWidget as follows, but with the same result: import sys from PyQt4 import QtCore, QtGui class Widget(QtGui.QWidget): def __init__(self, parent=None): QtGui.QWidget.__init__(self, parent) model = QtGui.QFileSystemModel() parentIndex = model.index(QtCore.QDir.currentPath()) print model.isDir(parentIndex) print model.data(parentIndex).toString() childIndex = model.index(0, 0, parentIndex) print model.data(childIndex).toString() rows = model.rowCount(parentIndex) print rows def main(): app = QtGui.QApplication(sys.argv) widget = Widget() widget.show() sys.exit(app.exec_()) if __name__ == '__main__': main()

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  • Prove correctness of unit test

    - by Timo Willemsen
    I'm creating a graph framework for learning purposes. I'm using a TDD approach, so I'm writing a lot of unit tests. However, I'm still figuring out how to prove the correctness of my unit tests For example, I have this class (not including the implementation, and I have simplified it) public class SimpleGraph(){ //Returns true on success public boolean addEdge(Vertex v1, Vertex v2) { ... } //Returns true on sucess public boolean addVertex(Vertex v1) { ... } } I also have created this unit tests @Test public void SimpleGraph_addVertex_noSelfLoopsAllowed(){ SimpleGraph g = new SimpleGraph(); Vertex v1 = new Vertex('Vertex 1'); actual = g.addVertex(v1); boolean expected = false; boolean actual = g.addEdge(v1,v1); Assert.assertEquals(expected,actual); } Okay, awesome it works. There is only one crux here, I have proved that the functions work for this case only. However, in my graph theory courses, all I'm doing is proving theorems mathematically (induction, contradiction etc. etc.). So I was wondering is there a way I can prove my unit tests mathematically for correctness? So is there a good practice for this. So we're testing the unit for correctness, instead of testing it for one certain outcome.

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  • Why doesn't the Java Collections API include a Graph implementation?

    - by dvanaria
    I’m currently learning the Java Collections API and feel I have a good understanding of the basics, but I’ve never understood why this standard API doesn’t include a Graph implementation. The three base classes are easily understandable (List, Set, and Map) and all their implementations in the API are mostly straightforward and consistent. Considering how often graphs come up as a potential way to model a given problem, this just doesn’t make sense to me (it’s possible it does exist in the API and I’m not looking in the right place of course). Steve Yegge suggests in one of his blog posts that a programmer should consider graphs first when attacking a problem, and if the problem domain doesn’t fit naturally into this data structure, only then consider the alternative structures. My first guess is that there is no universal way to represent graphs, or that their interfaces may not be generic enough for an API implementation to be useful? But if you strip down a graph to its basic components (vertices and a set of edges that connect some or all of the vertices) and consider the ways that graphs are commonly constructed (methods like addVertex(v) and insertEdge(v1, v2)) it seems that a generic Graph implementation would be possible and useful. Thanks for helping me understand this better.

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  • asp.net master page/content page interaction with style sheet

    - by Matt
    Learning how to do a master page in asp.net. Trying to figure out how my style sheet interacts with respects to the master page and content page. I can get HTML tags like body and the style sheet to react. But when I call the ID attribute of a label no styling takes place. What am I missing here as far as interaction? BTW I'm using VS2008 CSS sample: body { height:1200px; width:920px; border-style:solid; border-color:blue; padding:10px 10px 10px 10px; } #toptext1 { position:relative; top:-225px; right:-500px; font-size:22px; font-weight:bold; } From the master page: <body> <form id="form1" runat="server"> <asp:image id="cookNookLogo" ImageUrl="images/Logo.gif" runat="server" AlternateText="CookNook" Width="449px"></asp:image> <p> <asp:Label ID="toptext1" runat="server" Text="Quality Recipes, Hints and Supplies"></asp:Label> </p> From the content page: <%@ Page Language="C#" MasterPageFile="~/CNMasterPage.master" AutoEventWireup="true" CodeFile="Home.aspx.cs" Inherits="Home" Title="Untitled Page" %> <asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server"> <link href="App_Themes/cn/cn.css" rel="stylesheet" type="text/css" /> </asp:Content> When I was doing this without a master page it worked so where am I going wrong with the attributes?

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  • opengl + glew in Eclipse (for windows)

    - by echo
    I'm trying to get glew to work under eclipse (mingw) in windows. Seems as if it is extremely unusual not to use Visual Studio in this context. The install instructions for glew is simply "use the project file in build/vc6/"... The glew readme also writes: "If you wish to build GLEW from scratch (update the extension data from the net or add your own extension information), you need a Unix environment (including wget, perl, and GNU make). The extension data is regenerated from the top level source directory with: make extensions" In order to get glew to work in eclipse and windows I have to compile it in a unix environment? Is there no other way? Sure, it would probably be a learning experience to pull that off (if I were to succeed) but I feel that my time is best spent actually working on my project. And even if I did manage to crosscompile everything, would it work in anything but Visual Studio? Is the whole thing unfeasible and the best solution is to install Visual Studio? Google haven't been of much help, I feel like I am the only one that has ever attempted to do this (is there a good reason this?).

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