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  • Java Concurrency in practice sample question

    - by andy boot
    I am reading "Java Concurrency in practice" and looking at the example code on page 51. According to the book this piece of code is at risk of of failure if it has not been published properly. Because I like to code examples and break them to prove how they work. I have tried to make it throw an AssertionError but have failed. (Leading me to my previous question) Can anyone post sample code so that an AssertionError is thrown? Rule: Do not modify the Holder class. public class Holder{ private int n; public Holder(int n){ this.n = n; } public void assertSanity(){ if (n != n) { throw new AssertionError("This statement is false"); } } } I have modified the class to make it more fragile but I still can not get an AssertionError thrown. class Holder2{ private int n; private int n2; public Holder2(int n) throws InterruptedException{ this.n = n; Thread.sleep(200); this.n2 = n; } public void assertSanity(){ if (n != n2) { throw new AssertionError("This statement is false"); } } } Is it possible to make either of the above classes throw an AssertionError? Or do we have to accept that they may occasionally do so and we can't write code to prove it?

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  • Question about compilers and how they work

    - by Marin Doric
    This is the C code that frees memory of a singly linked list. It is compiled with Visual C++ 2008 and code works as it should be. /* Program done, so free allocated memory */ current = head; struct film * temp; temp = current; while (current != NULL) { temp = current->next; free(current); current = temp; } But I also encountered ( even in a books ) same code written like this: /* Program done, so free allocated memory */ current = head; while (current != NULL) { free(current); current = current->next; } If I compile that code with my VC++ 2008, program crashes because I am first freeing current and then assigning current-next to current. But obviously if I compile this code with some other complier ( for example, compiler that book author used ) program will work. So question is, why does this code compiled with specific compiler work? Is it because that compiler put instructions in binary file that remember address of current-next although I freed current and my VC++ doesn't. I just want to understand how compilers work.

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  • How to obtain the panel within a treeview (WPF)

    - by sperling
    How can one obtain the panel that is used within a TreeView? I've read that by default TreeView uses a VirtualizingStackPanel for this. When I look at a TreeView template, all I see is <ItemsPresenter />, which seems to hide the details of what panel is used. Possible solutions: 1) On the treeview instance ("tv"), from code, do this: tv.ItemsPanel. The problem is, this does not return a panel, but an ItemsPanelTemplate ("gets or sets the template that defines the panel that controls the layout of the items"). 2) Make a TreeView template that explicitly replaces <ItemsPresenter /> with your own ItemsControl.ItemsPanel. I am providing a special template anyways, so this is fine in my scenario. Then give a part name to the panel that you place within that template, and from code you can obtain that part (i.e. the panel). The problem with this? see below. (I am using a control named VirtualTreeView which is derived from TreeView, as is seen below): , use following: -- [sorry folks about poor formatting here, this is my first post, I tried 4 spaces for code... doesn't seem to work?] [I stripped out all clutter here for visibility...] The problem with this is: this immediately overrides any TreeView layout mechanism. Actually, you just get a blank screen, even when you have TreeViewItems filling the tree. Well, the reason I want to get a hold of the panel is to take some part in the MeaureOverride, but without going into all of that, I certainly do not want to rewrite the book of how to layout a treeview. I.e., doing this the step #2 way seems to invalidate the point of even using a TreeView in the first place. Sorry if there is some confusion here, thanks for any help you can offer.

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  • Inconsistent behavior working with "Flex on Rails" example.

    - by kmontgom
    I'm experimenting with Flex and Rails right now (Rails is cool). I'm following the examples in the book "Flex on Rails", and I'm getting some puzzling and inconsistent behavior. Heres the Flex MXML: <mx:HTTPService id="index" url="http://localhost:3000/people.xml" resultFormat="e4x" /> <mx:DataGrid dataProvider="{index.lastResult.person}" width="100%" height="100%"> <mx:columns> <mx:DataGridColumn headerText="First Name" dataField="first-name"/> <mx:DataGridColumn headerText="Last Name" dataField="last-name"/> </mx:columns> </mx:DataGrid> <mx:Script> <![CDATA[ import mx.controls.Alert; private function main():void { Alert.show( "In main()" ); } ]]> </mx:Script> When I run the app from my IDE (Amythyst beta, also cool), the DataGrid appears, but is not populated. The Alert.show() also triggers. When I go out to a web browser and manually enter the url (http://localhost:3000/people.xml), the Mongrel console shows the request coming through and the browser shows the web response. No exceptions or other error messages occur. Whats the difference? Do I need to alter some OS setting? I'm using Win7 on an x64 machine.

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  • Finding character in String in Vector.

    - by SoulBeaver
    Judging from the title, I kinda did my program in a fairly complicated way. BUT! I might as well ask anyway xD This is a simple program I did in response to question 3-3 of Accelerated C++, which is an awesome book in my opinion. I created a vector: vector<string> countEm; That accepts all valid strings. Therefore, I have a vector that contains elements of strings. Next, I created a function int toLowerWords( vector<string> &vec ) { for( int loop = 0; loop < vec.size(); loop++ ) transform( vec[loop].begin(), vec[loop].end(), vec[loop].begin(), ::tolower ); that splits the input into all lowercase characters for easier counting. So far, so good. I created a third and final function to actually count the words, and that's where I'm stuck. int counter( vector<string> &vec ) { for( int loop = 0; loop < vec.size(); loop++ ) for( int secLoop = 0; secLoop < vec[loop].size(); secLoop++ ) { if( vec[loop][secLoop] == ' ' ) That just looks ridiculous. Using a two-dimensional array to call on the characters of the vector until I find a space. Ridiculous. I don't believe that this is an elegant or even viable solution. If it was a viable solution, I would then backtrack from the space and copy all characters I've found in a separate vector and count those. My question then is. How can I dissect a vector of strings into separate words so that I can actually count them? I thought about using strchr, but it didn't give me any epiphanies.

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  • WPF: How to bind and update display with DataContext

    - by Am
    I'm trying to do the following thing: I have a TabControl with several tabs. Each TabControlItem.Content points to PersonDetails which is a UserControl Each BookDetails has a dependency property called IsEditMode I want a control outside of the TabControl , named ToggleEditButton, to be updated whenever the selected tab changes. I thought I could do this by changing the ToggleEditButton data context, by it doesn't seem to work (but I'm new to WPF so I might way off) The code changing the data context: private void tabControl1_SelectionChanged(object sender, SelectionChangedEventArgs e) { if (e.Source is TabControl) { if (e.Source.Equals(tabControl1)) { if (tabControl1.SelectedItem is CloseableTabItem) { var tabItem = tabControl1.SelectedItem as CloseableTabItem; RibbonBook.DataContext = tabItem.Content as BookDetails; ribbonBar.SelectedTabItem = RibbonBook; } } } } The DependencyProperty under BookDetails: public static readonly DependencyProperty IsEditModeProperty = DependencyProperty.Register("IsEditMode", typeof (bool), typeof (BookDetails), new PropertyMetadata(true)); public bool IsEditMode { get { return (bool)GetValue(IsEditModeProperty); } set { SetValue(IsEditModeProperty, value); SetValue(IsViewModeProperty, !value); } } And the relevant XAML: <odc:RibbonTabItem Title="Book" Name="RibbonBook"> <odc:RibbonGroup Title="Details" Image="img/books2.png" IsDialogLauncherVisible="False"> <odc:RibbonToggleButton Content="Edit" Name="ToggleEditButton" odc:RibbonBar.MinSize="Medium" SmallImage="img/edit_16x16.png" LargeImage="img/edit_32x32.png" Click="Book_EditDetails" IsChecked="{Binding Path=IsEditMode, Mode=TwoWay}"/> ... There are two things I want to accomplish, Having the button reflect the IsEditMode for the visible tab, and have the button change the property value with no code behind (if posible) Any help would be greatly appriciated.

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  • (500) Internal Server Error with C# and Web Dev 2008 Express

    - by user32848
    The code below is generic, found in a variety of places, including a book I have. I have used it as a base for a working program in VS 2005. Now I've resurrected it with my current Visual Web Developer 2008 Express Edition and I seem to have problems connecting it to my default development server (I don't have IIS on my XP). The error is: (500) Internal Server Error. Is this saying what I thought it did (above) or something else, and how do I solve this problem? using System; using System.Collections; using System.Collections.Generic; using System.Configuration; using System.IO; using System.Net; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.Text.RegularExpressions; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string strResult = ""; string url = "http://weather.unisys.com"; WebResponse objResponse; WebRequest objRequest; try { objRequest = System.Net.HttpWebRequest.Create(url); } catch { objRequest = System.Net.HttpWebRequest.Create("http://"+ url); } objResponse = objRequest.GetResponse(); using (StreamReader sr = new StreamReader(objResponse.GetResponseStream())) { strResult = sr.ReadToEnd(); sr.Close(); } } }

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  • PHP Installer Script

    - by totallymike
    I'm looking to create a fully functional installer for a slightly complicated web application using PHP. Basically, you go to URL/setup.php and you are asked a series of questions, and during the process a database is set up and a config file is populated according to the answers given. A good example of this is how Wordpress handles its install procedure, as well as any number of PHP applications. My question to you, oh great internet, is this: This technique is so prevalent that surely not everyone is re-inventing the wheel, is there a place I can go to find a basic walkthrough (not code, just a description) of the technique. Either that or a good book which outlines if not this specific technique, then the fundamentals relevant to this? I can bang out something ugly and probably make it work myself, but if there's a best known method I'd like to find it. Far more important than having a working function is to have a description of what's going on from step to step. I'd like to have the installer, but I really want to learn how it's done. Thanks, Mike

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  • PHP: passing a function with parameters as parameter

    - by Oden
    Hey, I'm not sure that silly question, but I ask: So, if there is an anonymous function I can give it as another anonymous functions parameter, if it has been already stored a variable. But, whats in that case, if I have stored only one function in a variable, and add the second directly as a parameter into it? Can I add parameters to the non-stored function? Fist example (thats what i understand :) ): $func = function($str){ return $str; }; $func2 = function($str){ return $str; }; $var = $func($func2('asd')); var_dump($var); // prints out string(3) "asd" That makes sense for me, but what is with the following one? $func = function($str){ return $str; }; $var = $func(function($str = "asd"){ return $str; }); var_dump($var); /** This prints out: object(Closure)#1 (1) { ["parameter"]=> array(1) { ["$str"]=> string(10) "" } } But why? */ And at the end, can someone recommend me a book or an article, from what i can learn this lambda coding feature of php? Thank you in advance for your answers :)

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  • Lookup table size reduction

    - by Ryan
    Hello: I have an application in which I have to store a couple of millions of integers, I have to store them in a Look up table, obviously I cannot store such amount of data in memory and in my requirements I am very limited I have to store the data in an embebedded system so I am very limited in the space, so I would like to ask you about recommended methods that I can use for the reduction of the look up table. I cannot use function approximation such as neural networks, the values needs to be in a table. The range of the integers is not known at the moment. When I say integers I mean a 32 bit value. Basically the idea is use some copmpression method to reduce the amount of memory but without losing many precision. This thing needs to run in hardware so the computation overhead cannot be very high. In my algorithm I have to access to one value of the table do some operations with it and after update the value. In the end what I should have is a function which I pass an index to it and then I get a value, and after I have to use another function to write a value in the table. I found one called tile coding http://www.cs.ualberta.ca/~sutton/book/8/node6.html, this one is based on several look up tables, does anyone know any other method?. Thanks.

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  • Have you considered doing revenue sharing to fund development of a mobile app? How would you do it?

    - by Brennan
    I am looking to build multiple mobile apps which leverage existing content and resources by enabling these mobile apps with web services. I will duplication much of the same features which are also in place and add more features that are possible on a mobile device like address book, maps and calendar integration to make the service much more useful. To fund these projects I see that I have 2 options. First I could simply quote them for the project based on my hourly rate and the estimate in hours that I will take the to complete the job. That may be a high number. The second option would be to do shared revenue with ads placed in the app. I could then take a percentage of any revenue that is generated from the app. There is also a hybrid where I might charge for a percentage of the estimated quote and then take a percentage of the revenue sharing. So my question is how much should I propose for the revenue sharing? Should it be 30%? Or maybe I should make it 70% up to a point that a certain dollar amount is reached? And should the revenue sharing agreement be for 12 months, 24 months or more? Should I include in the proposal an agreement that they will help promote this app with their content and resources? Ultimately this system will benefit both sides because it extends their reach into the mobile space instead of where they are currently with just print and web. I have tried to find some examples with a few Google searches but I keep hitting content about the Google and Apple revenue sharing models. I would like to get some solid examples that are working to compare against so that my proposal do build these apps is not completely off base.

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  • How to (unit-)test data intensive PL/SQL application

    - by doom2.wad
    Our team is willing to unit-test a new code written under a running project extending an existing huge Oracle system. The system is written solely in PL/SQL, consists of thousands of tables, hundreds of stored procedures packages, mostly getting data from tables and/or inserting/updating other data. Our extension is not an exception. Most functions return data from a quite complex SELECT statementa over many mutually bound tables (with a little added logic before returning them) or make transformation from one complicated data structure to another (complicated in another way). What is the best approach to unit-test such code? There are no unit tests for existing code base. To make things worse, only packages, triggers and views are source-controlled, table structures (including "alter table" stuff and necessary data transformations are deployed via channel other than version control). There is no way to change this within our project's scope. Maintaining testing data set seems to be impossible since there is new code deployed to the production environment on weekly basis, usually without prior notice, often changing data structure (add a column here, remove one there). I'd be glad for any suggestion or reference to help us. Some team members tend to be tired by figuring out how to even start for our experience with unit-testing does not cover PL/SQL data intensive legacy systems (only those "from-the-book" greenfield Java projects).

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  • What is wrong with accessing DBI directly?

    - by canavanin
    Hi everyone! I'm currently reading Effective Perl Programming (2nd edition). I have come across a piece of code which was described as being poorly written, but I don't yet understand what's so bad about it, or how it should be improved. It would be great if someone could explain the matter to me. Here's the code in question: sub sum_values_per_key { my ( $class, $dsn, $user, $password, $parameters ) = @_; my %results; my $dbh = DBI->connect( $dsn, $user, $password, $parameters ); my $sth = $dbh->prepare( 'select key, calculate(value) from my_table'); $sth->execute(); # ... fill %results ... $sth->finish(); $dbh->disconnect(); return \%results; } The example comes from the chapter on testing your code (p. 324/325). The sentence that has left me wondering about how to improve the code is the following: Since the code was poorly written and accesses DBI directly, you'll have to create a fake DBI object to stand in for the real thing. I have probably not understood a lot of what the book has so far been trying to teach me, or I have skipped the section relevant for understanding what's bad practice about the above code... Well, thanks in advance for your help!

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  • Is CakePhp 'standards compliant' when generating HTML, Forms, etc?

    - by dtj
    So I've been reading a lot of "Designing with Web Standards" and really enjoying it. I'm a big CakePhp user, and as I look at the source for various form elements that Cake creates with its FormHelper, I see all sorts of extraneous In the book, he promotes semantic HTML, and writing your markup as simple / generic as possible. So my question is, am I better writing my own HTML in these situations? I really want to work in compliance with XHTML and CSS standards, and it seems I'd spend just as much time (if not more) cleaning up Cakes HTML, when I could just write my own thoughts? p.s. Here's an example in an out of the box form that CakePhp generates using the FormHelper <form id="CompanyAddForm" method="post" action="/omni_cake/companies/add" accept-charset="utf-8"><div style="display:none;"><input type="hidden" name="_method" value="POST" /></div> <div class="input text required"><label for="CompanyName">Name</label><input name="data[Company][name]" type="text" maxlength="50" id="CompanyName" /></div> <div class="input text required"><label for="CompanyWebsite">Website</label><input name="data[Company][website]" type="text" maxlength="50" id="CompanyWebsite" /></div> <div class="input textarea"><label for="CompanyNotes">Notes</label><textarea name="data[Company][notes]" cols="30" rows="6" id="CompanyNotes" ></textarea></div> <div class="submit"><input type="submit" value="Submit" /></div></form>

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  • implementing cryptographic algorithms, specifically the key expansion part

    - by masseyc
    Hey, recently I picked up a copy of Applied Cryptography by Bruce Schneier and it's been a good read. I now understand how several algorithms outlined in the book work, and I'd like to start implementing a few of them in C. One thing that many of the algorithms have in common is dividing an x-bit key, into several smaller y-bit keys. For example, blowfish's key, X, is 64-bits, but you are required to break it up into two 32-bit halves; Xl and Xr. This is where I'm getting stuck. I'm fairly decent with C, but I'm not the strongest when it comes to bitwise operators and the like. After some help on IRC, I managed to come up with these two macros: #define splitup(a, b, c) {b = a >> 32; c = a & 0xffffffff; } #define combine(a, b, c) {a = (c << 32) | a;} Where a is 64 bits and b and c are 32 bits. However, the compiler warns me about the fact that I'm shifting a 32 bit variable by 32 bits. My questions are these: what's bad about shifting a 32-bit variable 32 bits? I'm guessing it's undefined, but these macros do seem to be working. Also, would you suggest I go about this another way? As I said, I'm fairly familiar with C, but bitwise operators and the like still give me a headache.

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  • UITableView with dynamic cell heights -- what do I need to do to fix scrolling down?

    - by Ian Terrell
    I am building a teensy tiny little Twitter client on the iPhone. Naturally, I'm displaying the tweets in a UITableView, and they are of course of varying lengths. I'm dynamically changing the height of the cell based on the text quite fine: - (CGFloat)heightForTweetCellWithString:(NSString *)text { CGFloat height = Buffer + [text sizeWithFont:Font constrainedToSize:Size lineBreakMode:LineBreakMode].height; return MAX(height, MinHeight); } - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { NSString *text = // get tweet text for this indexpath return [self heightForTweetCellWithString:text]; } } I'm displaying the actual tweet cell using the algorithm in the PragProg book: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"TweetCell"; TweetCell *cell = (TweetCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [self createNewTweetCellFromNib]; } cell.tweet.text = // tweet text // set other labels, etc return cell; } When I boot up, all the tweets visible display just fine. However, when I scroll down, the tweets below are quite mussed up -- it appears that once a cell has scrolled off the screen, the cell height for the one above it gets resized to be larger than it should be, and obscures part of the cell below it. When the cell reaches the top of the view, it resets itself and renders properly. Scrolling up presents no difficulties. Here is a video that shows this in action: http://screencast.com/t/rqwD9tpdltd I've tried quite a bit already: resizing the cell's frame on creation, using different identifiers for cells with different heights (i.e. [NSString stringWithFormat:@"Identifier%d", rowHeight]), changing properties in Interface Builder... If there are additional code snippets I can post, please let me know. Thanks in advance for your help!

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  • PHP check http referer for form submitted by AJAX, secure?

    - by Michael Mao
    Hi all: This is the first time I am working for a front-end project that requires server-side authentication for AJAX requests. I've encountered problems like I cannot make a call of session_start as the beginning line of the "destination page", cuz that would get me a PHP Warning : Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at C:\xampp\htdocs\comic\app\ajaxInsert Book.php:1) in C:\xampp\htdocs\comic\app\common.php on line 10 I reckon this means I have to figure out a way other than checking PHP session variables to authenticate the "caller" of this PHP script, and this is my approach : I have a "protected" PHP page, which must be used as the "container" of my javascript that posts the form through jQuery $.ajax(); method In my "receiver" PHP script, what I've got is: <?php define(BOOKS_TABLE, "books"); define(APPROOT, "/comic/"); define(CORRECT_REFERER, "/protected/staff/addBook.php"); function isRefererCorrect() { // the following line evaluates the relative path for the referer uri, // Say, $_SERVER['HTTP_REFERER'] returns "http://localhost/comic/protected/staff/addBook.php" // Then the part we concern is just this "/protected/staff/addBook.php" $referer = substr($_SERVER['HTTP_REFERER'], 6 + strrpos($_SERVER['HTTP_REFERER'], APPROOT)); return (strnatcmp(CORRECT_REFERER, $referer) == 0) ? true : false; } //http://stackoverflow.com/questions/267546/correct-http-header-for-json-file header('Content-type: application/json charset=UTF-8'); header('Cache-Control: no-cache, must-revalidate'); echo json_encode(array ( "feedback"=>"ok", "info"=>isRefererCorrect() )); ?> My code works, but I wonder is there any security risks in this approach? Can someone manipulate the post request so that he can pretend that the caller javascript is from the "protected" page? Many thanks to any hints or suggestions.

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  • Technology and language for a stable Digital Audio Workstation development

    - by Kill KRT
    Hi, I'm designing a cross platform (Windows/Linux/OS X) application, something like a digital audio workstation. I'd like to create a software where users have a fully featured sequencer (multiple tracks with automation) and where it is possible to create instruments using a visual language (as Pure Data/Max MSP). Ehm... I know that I've already posted a question about a related issue... But in order to decide which technology I should use, I think I'd better to make more investigation. I'm a quite experted user of audio trackers (Renoise, Protracker,...) and sequencers (FL Studio, Cubase 5), but I didn't ever try to develop even a basic audio tracker. I know just the basic theory of mixing sound and know how basically a DSP works. My questions are: Where I can find a good tutorial/guide/book about this issue? Do you think using C# (with NAudio) could dramatically reduce performance? I know C++ would be the best choice, but I find C# so elegant and easy to build and port, while C++ is so powerful and fast, but there are too #define and bad things for my taste! ;-) Thank you.

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  • csrf error in django

    - by niklasfi
    Hello, I want to realize a login for my site. I basically copied and pasted the following bits from the Django Book together. However I still get an error (CSRF verification failed. Request aborted.), when submitting my registration form. Can somebody tell my what raised this error and how to fix it? Here is my code: views.py: # Create your views here. from django import forms from django.contrib.auth.forms import UserCreationForm from django.http import HttpResponseRedirect from django.shortcuts import render_to_response def register(request): if request.method == 'POST': form = UserCreationForm(request.POST) if form.is_valid(): new_user = form.save() return HttpResponseRedirect("/books/") else: form = UserCreationForm() return render_to_response("registration/register.html", { 'form': form, }) register.html: <html> <body> {% block title %}Create an account{% endblock %} {% block content %} <h1>Create an account</h1> <form action="" method="post">{% csrf_token %} {{ form.as_p }} <input type="submit" value="Create the account"> </form> {% endblock %} </body> </html>

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  • Can this extension method be improved?

    - by Newbie
    I have the following extension method public static class ListExtensions { public static IEnumerable<T> Search<T>(this ICollection<T> collection, string stringToSearch) { foreach (T t in collection) { Type k = t.GetType(); PropertyInfo pi = k.GetProperty("Name"); if (pi.GetValue(t, null).Equals(stringToSearch)) { yield return t; } } } } What it does is by using reflection, it finds the name property and then filteres the record from the collection based on the matching string. This method is being called as List<FactorClass> listFC = new List<FactorClass>(); listFC.Add(new FactorClass { Name = "BKP", FactorValue="Book to price",IsGlobal =false }); listFC.Add(new FactorClass { Name = "YLD", FactorValue = "Dividend yield", IsGlobal = false }); listFC.Add(new FactorClass { Name = "EPM", FactorValue = "emp", IsGlobal = false }); listFC.Add(new FactorClass { Name = "SE", FactorValue = "something else", IsGlobal = false }); List<FactorClass> listFC1 = listFC.Search("BKP").ToList(); It is working fine. But a closer look into the extension method will reveal that Type k = t.GetType(); PropertyInfo pi = k.GetProperty("Name"); is actually inside a foreach loop which is actually not needed. I think we can take it outside the loop. But how? PLease help. (C#3.0)

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  • Why is debugging better in an IDE?

    - by Bill Karwin
    I've been a software developer for over twenty years, programming in C, Perl, SQL, Java, PHP, JavaScript, and recently Python. I've never had a problem I could not debug using some careful thought, and well-placed debugging print statements. I respect that many people say that my techniques are primitive, and using a real debugger in an IDE is much better. Yet from my observation, IDE users don't appear to debug faster or more successfully than I can, using my stone knives and bear skins. I'm sincerely open to learning the right tools, I've just never been shown a compelling advantage to using visual debuggers. Moreover, I have never read a tutorial or book that showed how to debug effectively using an IDE, beyond the basics of how to set breakpoints and display the contents of variables. What am I missing? What makes IDE debugging tools so much more effective than thoughtful use of diagnostic print statements? Can you suggest resources (tutorials, books, screencasts) that show the finer techniques of IDE debugging? Sweet answers! Thanks much to everyone for taking the time. Very illuminating. I voted up many, and voted none down. Some notable points: Debuggers can help me do ad hoc inspection or alteration of variables, code, or any other aspect of the runtime environment, whereas manual debugging requires me to stop, edit, and re-execute the application (possibly requiring recompilation). Debuggers can attach to a running process or use a crash dump, whereas with manual debugging, "steps to reproduce" a defect are necessary. Debuggers can display complex data structures, multi-threaded environments, or full runtime stacks easily and in a more readable manner. Debuggers offer many ways to reduce the time and repetitive work to do almost any debugging tasks. Visual debuggers and console debuggers are both useful, and have many features in common. A visual debugger integrated into an IDE also gives you convenient access to smart editing and all the other features of the IDE, in a single integrated development environment (hence the name).

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  • django simple approach to multi-field search

    - by Scott Willman
    I have a simple address book app that I want to make searchable. The model would look something like: class Address(models.Model): address1 = models.CharField("Address Line 1", max_length=128) address2 = models.CharField("Address Line 2", max_length=128) city = models.CharField("City", max_length=128) state = models.CharField("State", max_length=24) zipCode = models.CharField("Zip Code", max_length=24) def __unicode__(self): return "%s %s, %s, %s, %s" % (self.address1, self.address2, self.city, self.state, self.zipCode) class Entry(models.Model): name = models.CharField("Official School Name", max_length=128) createdBy = models.ForeignKey(User) address = models.ForeignKey(Address, unique=True) def __unicode__(self): return "%s - %s, %s" % (self.name, self.address.city, self.address.state) I want the searching to be fairly loose, like: Bank of America Los Angeles 91345. It seems like I want a field that contains all of those elements into one that I can search, but that also seems redundant. I was hoping I could add a method to the Entry model like this: def _getSearchText(self): return "%s %s %s" % (self.name, self.address, self.mascot) searchText = property(_getSearchText) ...and search that as a field, but I suppose that's wishful thinking... How should I approach this using basic Django and SqLite (this is a learning exercise). Thank you!!

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  • Where can a self-teacher learn general good programming habits and conventions?

    - by lucid
    A few mistakes and general childishness in early adulthood have left me in a situation where I work a menial job, with no possibility (in the near future) of attending school. I aspire to one day work in the programming field (gaming specifically), after proving myself on the indie end of things. I've gotten very confident in C++, java, and python, and I find I'm able to solve any problem I want either from previous experience, or from scouring the web for help. The solutions work, and with each attempt they become more readable, maintainable, and extensible. But this is because I'm learning from mistakes and bad programming and design habits I feel I might have avoided with actual schooling. General tips like: "if it's hard to read or getting long, or you're writing it twice, it should be in one or more functions." or "design all your classes before you start coding, so you don't have to rewrite classes later when you discover an unforeseen dependency" Is there a good book or website for learning general good programming practices and design habits? Also, naming and format conventions. I realize sometimes development houses have their own conventions, but things like "Classes in python usually have the first letter of each word capitalized". I'd like to be able to show some source code to a potential employer, and be prepared when for what's expected on a team. Is there some central database of naming and formatting conventions somewhere? Also, feel free to give any thoughts on whether or not the self-teach, garner some indie sales, use them as your resume' route is realistic

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  • How to install Zend Framework on Windows

    - by sombe
    "installing Zend Framework is so easy!!!!" yeah right... Ok I'm working with a beginner's book and the ONE thing that is not excessively detailed is the most important part: Installing the darn thing. After browsing the quickstart guide for hours, all it said was: "download Zend [...] add the include directory (bla bla) and YOU'RE DONE!" right, i'm done using Zend. Ok, not really, not yet anyway. I beg of you people, I wanna go to bed, please tell me how (in simple 6th grade detail) to install the framework. I've got the unzipped folder in my htdocs directory, and I placed zf.bat+zf.php in the htdocs root. What's next? thank you so much. EDIT: Thanks guys for all the answers. Unfortunately I haven't been able to work with this or find a good enough resource to explain it to me in plain english. It seems that this framework adheres more so to programmers than to beginners. I've since yesterday read a little on CakePHP and found that it was incredibly easy to install and tune. As oppose to Zend Framework, where I had to dig in my "environment variables", configure "httpd.conf" and almost tie the knot between my computer driver cables to just get it running, CakePHP has already allowed me to put together a nice newbie application. In conclusion, I very much appreciate all of your help. I hope someone else venturing on ZF will be more successful with it. Thanks!

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  • Setup SVN/LAMP/Test Server/ on linux, where to start?

    - by John Isaacks
    I have a ubuntu machine I have setup. I installed apache2 and php5 on it. I can access the web server from other machines on the network via http://linux-server. I have subversion installed on it. I also have vsftpd installed on it so I can ftp to it from another computer on the network. Myself and other users currently use dreamweaver to checkin-checkout files directly from our live site to make changes. I want the connect to the linux server from pc. make the changes on the test server until ready and then pushed to the live site. I want to use subversion also into this workflow as well. but not sure what the best workflow is or how to set this up. I have no experience with linux, svn, or even using a test server, the checkin/out we are currently doing is the way I have always done it. I have hit many snags already just getting what I have setup because of my lack of knowledge in the area. Dreamweaver 5 has integration with subversion but I can't figure out how to get it to work. I want to setup and create the best workflow possible. I dont expect anyone to be able to give me an answer that will enlighten me enough to know everthing I need to know to do what I want to do (altough if possible that would be great) instead I am looking for maybe a knowledge path like answer. Like a general outline of what I need to do accompanied with links to learn how to do it. like read this book to learn linux, then read this article to learn svn, etc., then you should know what to do. I would be happy just getting it all setup, but I would like to know what I am actually doing while setting it up too.

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