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• What is the right approach to checksumming UDP packets

  - by mr.b

  I'm building UDP server application in C#. I've come across a packet checksum problem. As you probably know, each packet should carry some simple way of telling receiver if packet data is intact. Now, UDP already has 2-byte checksum as part of header, which is optional, at least in IPv4 world. Alternative method is to have custom checksum as part of data section in each packet, and to verify it on receiver. My question boils down to: is it better to rely on (optional) checksum in UDP packet header, or to make a custom checksum implementation as part of packet data section? Perhaps the right answer depends on circumstances (as usual), so one circumstance here is that, even though code is written and developed in .NET on Windows, it might have to run under platform-independent Mono.NET, so eventual solution should be compatible with other platforms. I believe that custom checksum algorithm would be easily portable, but I'm not so sure about the first one. Any thoughts? Also, shouts about packet checksumming in general are welcome.

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• How to select a rectangle from List<Rectangle[]> with Linq

  - by dboarman

  I have a list of DrawObject[]. Each DrawObject has a Rectangle property. Here is my event: List<Canvas.DrawObject[]> matrix; void Control_MouseMove ( object sender, MouseEventArgs e ) { IEnumerable<Canvas.DrawObject> tile = Enumerable.Range( 0, matrix.Capacity - 1) .Where(row => Enumerable.Range(0, matrix[row].Length -1) .Where(column => this[column, row].Rectangle.Contains(e.Location))) .????; } I am not sure exactly what my final select command should be in place of the "????". Also, I was getting an error: cannot convert IEnumerable to bool. I've read several questions about performing a linq query on a list of arrays, but I can't quite get what is going wrong with this. Any help? Edit Apologies for not being clear in my intentions with the implementation. I intend to select the DrawObject that currently contains the mouse location.

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• Problem consuming Exchange Web Service 2010 with jax-ws metro

  - by Johan Karlberg

  I am trying to consume the Exchange 2010 Web Service interface using JAX-WS. I'm using JAX-WS 2.2 RI (Metro 2.0). 2.1 exhibited the same problem. I am running into trouble with Exchange, which returns "HTTP/1.1 415 Cannot process the message because the content type 'text/xml;charset=utf-8' was not the expected type 'text/xml; charset=utf-8'." as a reponse (2.1 quoted the charset value, otherwise same response). Apparently I need to dictate the exact Content-type header for Exchange to be happy. Is there a way for me to do this without forcing me to manually rebuild the dependency? I currently rely on published maven artifacts, and would like to continue doing this if at all possible. The consuming process is a regular J2SE app, with no containers in sight. I have control of the application and can add pretty much anything required to the applications scope, but can not add out-of-process items like proxy servers. The client classes were generated from local WSDL, but the charset specification is derived from constants declared in the jaxws RI implementation, not the generated code. The resulting HTTP transport is thus handled by the standard http/https client from Sun JRE5 or JRE6.

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• Spring and hibernate.cfg.xml

  - by Steve Kuo

  How do I get Spring to load Hibernate's properties from hibernate.cfg.xml? We're using Spring and JPA (with Hibernate as the implementation). Spring's applicationContext.xml specifies the JPA dialect and Hibernate properties: <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean"> <property name="jpaDialect"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" /> </property> <property name="jpaProperties"> <props> <prop key="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</prop> </props> </property> </bean> In this configuration, Spring is reading all the Hibernate properties via applicationContext.xml . When I create a hibernate.cfg.xml (located at the root of my classpath, the same level as META-INF), Hibernate doesn't read it at all (it's completely ignored). What I'm trying to do is configure Hibernate second level cache by inserting the cache properties in hibernate.cfg.xml: <cache usage="transactional|read-write|nonstrict-read-write|read-only" region="RegionName" include="all|non-lazy" />

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• Silverlight - how to render image from non-visible data bound user control?

  - by MagicMax

  Hello! I have such situation - I'd like to build timeline control. So I have UserControl and ItemsControl on it (every row represents some person). The ItemsControl contains another ItemsControl as ItemsControl.ItemTemplate - it shows e.g. events for the person arranged by event's date. So it looks as some kind of grid with dates as a column headers and e.g. peoples as row headers. ........................|.2010.01.01.....2010.01.02.....2010.01.03 Adam Smith....|......[some event#1].....[some event#2]...... John Dow.......|...[some event#3].....[some event#4]......... I can have a lot of persons (ItemsControl #1 - 100-200 items) and a lot of events occured by some day (1-10-30 events per person in one day) the problem is that when user scrolls ItemsControl #1/#2 it happened toooo sloooooowwww due to a lot of elements should be rendered in one time (as I have e.g. a bit of text boxes and other elements in description of particular event) Question #1 - how can I improve it? May be somebody knows better way to build such user control? I have to mention that I'm using custom Virtual panel, based on some custom Virtual panel implementation found somewhere in internet... Question #2 - I'd like to make image with help of WriteableBitmap and render data bound control to image and to show image instead of a lot of elements. Problem is that I'm trying to render invisible data bound control (created in code behind) and it has actualWidth/Height equals to zero (so nothing rendered). How can I solve it? Thank you very much for you help!

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• onmouseover problems with JavaScript (rendered using django and django-imagekit)

  - by Michael Moreno

  I'm using Imagekit. View.py includes: def pics(request): p = Photo.objects.all() return render_to_response('Shots.html', {'p': p}) The following simple code in the template will generate associated images: {% for p in p %} <img src = "{{ p.display.url }}"> <img src = "{{ p.thumbnail_image.url }}"> {% endfor %} I'm attempting to generate a series of thumbnails {{ p.thumbnail_image.url }} which, when mouseover'd, will generate the slightly larger version of the image, {{ p.display.url }} via Javascript. The following code in the template attempts to do so: <html> <head> <HEAD> <script language="Javascript"> { image1 = new Image image2 = new Image image1.src = {{ p.thumbnail_image.url }} image2.src = {{ p.display.url }} </script> </head> <body> {% for p in p %} <a href="" onMouseOver="document.rollover.src= image2.src onMouseOut="document.rollover.src= image1.src"> <img src="{{ p.thumbnail_image.url }}" border=0 name="rollover"></a> {% endfor %} </body> </html> This will display the series of thumbnails, but the larger image will not display when mouseover'd. I believe it has to do with how I'm specifying the variable {{ p.display.url }}.

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• Why does my ActivePerl program report 'Sorry. Ran out of threads'?

  - by Zaid

  Tom Christiansen's example code (à la perlthrtut) is a recursive, threaded implementation of finding and printing all prime numbers between 3 and 1000. Below is a mildly adapted version of the script #!/usr/bin/perl # adapted from prime-pthread, courtesy of Tom Christiansen use strict; use warnings; use threads; use Thread::Queue; sub check_prime { my ($upstream,$cur_prime) = @_; my $child; my $downstream = Thread::Queue->new; while (my $num = $upstream->dequeue) { next unless ($num % $cur_prime); if ($child) { $downstream->enqueue($num); } else { $child = threads->create(\&check_prime, $downstream, $num); if ($child) { print "This is thread ",$child->tid,". Found prime: $num\n"; } else { warn "Sorry. Ran out of threads.\n"; last; } } } if ($child) { $downstream->enqueue(undef); $child->join; } } my $stream = Thread::Queue->new(3..shift,undef); check_prime($stream,2); When run on my machine (under ActiveState & Win32), the code was capable of spawning only 118 threads (last prime number found: 653) before terminating with a 'Sorry. Ran out of threads' warning. In trying to figure out why I was limited to the number of threads I could create, I replaced the use threads; line with use threads (stack_size => 1);. The resultant code happily dealt with churning out 2000+ threads. Can anyone explain this behavior?

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• Good Learning Method for Objective-C?

  - by Josh Kahane

  Hi I know this must be asked a millions times and can't be easy to answer as there is o definitive method, but any help would be appreciated, thanks. I have been playing around with all sorts of things in Xcode and with Objective-C, however I can't seem to find a good way of learning things in an efficient way. I have bought the book 'Programming in Objective-C 2.0' and its great but just lays down the basics it seems. I want to learn in the 2D game development direction, then of course 3D after nailing that, if thats the right thing to do? I am 17 currently in year 13, last year of school/A Levels and am almost definitely taking a gap year. Any good, well known reputable courses online or offline (real world)? This is my first programming language, and I am absolutely serious about learning this. One last question, is when learning things online, I have in the past started building a feature and learning a certain aspect in programming only to find out after adding more its slows down the app or its to inefficient. Is the key to use a certain method in a certain situation (being os many ways to do the same thing) or use any of those methods and refine it in your app to make it run smoothly? Sorry, its hard for me to know when I have little experience, thus far. Sorry for rambling on! I would appreciate any help, thank you!

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• JQuery Autocomplete plugin not working with JQuery 1.4.1

  - by Russ Clark

  I've been using the JQuery Autocomplete plugin with JQuery version 1.3.2, and it has been working great. I recently updated JQuery in my project to version 1.4.2, and the Autocomplete plugin is now broken. The JQuery code to add items to a textbox on my web page doesn't seem to be getting called at all. Does anyone know if the JQuery Autocomplete plugin is incompatible with JQuery version 1.4.2, and if there is a fix for this problem? Here is some sample code I've built in an ASP.Net web site (which works fine if I change the JQuery file to jquery-1.3.2.js, but nothing happens using jquery-1.4.2.js): <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Untitled Page</title> <script type="text/javascript" src="js/jquery-1.4.2.js" ></script> <script type="text/javascript" src="js/jquery.autocomplete.js" ></script> <script type="text/javascript"> $(document).ready(function() { var data = "Core Selectors Attributes Traversing Manipulation CSS Events Effects Ajax Utilities".split(" "); $(':input:text:id$=sapleUser').autocomplete(data); }); </script> </head> <body> <form id="form1" runat="server"> API Reference: <input id="sapleUser" autocomplete="off" type="text" runat="server" /> (try "C" or "E") </form> </body> </html>

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• What is Ruby's analog to Python Metaclasses?

  - by Sean Copenhaver

  Python has the idea of metaclasses that, if I understand correctly, allow you to modify an object of a class at the moment of construction. You are not modifying the class, but instead the object that is to be created then initialized. Python (at least as of 3.0 I believe) also has the idea of class decorators. Again if I understand correctly, class decorators allow the modifying of the class definition at the moment it is being declared. Now I believe there is an equivalent feature or features to the class decorator in Ruby, but I'm currently unaware of something equivalent to metaclasses. I'm sure you can easily pump any Ruby object through some functions and do what you will to it, but is there a feature in the language that sets that up like metaclasses do? So again, Does Ruby have something similar to Python's metaclasses? Edit I was off on the metaclasses for Python. A metaclass and a class decorator do very similar things it appears. They both modify the class when it is defined but in different manners. Hopefully a Python guru will come in and explain better on these features in Python. But a class or the parent of a class can implement a __new__(cls[,..]) function that does customize the construction of the object before it is initialized with __init__(self[,..]).

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• SerializationException with custom GenericIdentiy?

  - by MunkiPhD

  I'm trying to implement my own GenericIdentity implementation but keep receiving the following error when it attempts to load the views (I'm using asp.net MVC): System.Runtime.Serialization.SerializationException was unhandled by user code Message="Type is not resolved for member 'OpenIDExtendedIdentity,Training.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'." Source="WebDev.WebHost" I've ended up with the following class: [Serializable] public class OpenIDExtendedIdentity : GenericIdentity { private string _nickName; private int _userId; public OpenIDExtendedIdentity(String name, string nickName, int userId) : base(name, "OpenID") { _nickName = nickName; _userId = userId; } public string NickName { get { return _nickName; } } public int UserID { get { return _userId; } } } In my Global.asax I read a cookie's serialized value into a memory stream and then use that to create my OpenIDExtendedIdentity object. I ended up with this attempt at a solution after countless tries of various sorts. It works correctly up until the point where it attempts to render the views. What I'm essentially attempting to achieve is the ability to do the following (While using the default Role manager from asp.net): User.Identity.UserID User.Identity.NickName ... etc. I've listed some of the sources I've read in my attempt to get this resolved. Some people have reported a Cassini error, but it seems like others have had success implementing this type of custom functionality - thus a boggling of my mind. http://forums.asp.net/p/32497/161775.aspx http://ondotnet.com/pub/a/dotnet/2004/02/02/effectiveformsauth.html http://social.msdn.microsoft.com/Forums/en-US/netfxremoting/thread/e6767ae2-dfbf-445b-9139-93735f1a0f72

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• TCL How to read , extract and count the occurent in .txt file (Current Directory)

  - by Passion

  Hi Folks, I am beginner to scripting and vigorously learning TCL for the development of embedded system. I have to Search for the files with only .txt format in the current directory, count the number of cases of each different "Interface # nnnn" string in .txt file, where nnnn is a four or 32 digits max hexadecimal no and o/p of a table of Interface number against occurrence. I am facing implementation issues while writing a script i.e, Unable to implement the data structure like Linked List, Two Dimensional array. I am rewriting a script using multi dimension array (Pass values into the arrays in and out of procedure) in TCL to scan through the every .txt file and search for the the string/regular expression ‘Interface # ’ to count and display the number of occurrences. If someone could help me to complete this part will be much appreciated. Search for only .txt extension files and obtain the size of the file Here is my piece of code for searching a .txt file in present directory set files [glob *.txt] if { [llength $files] > 0 } { puts "Files:" foreach f [lsort $files] { puts " [file size $f] - $f" } } else { puts "(no files)" } I reckon these are all the possible logical steps behind to complete it i) Once searched and find the .txt file then open all .txt files in read only mode ii) Create a array or list using the procedure (proc) Interface number to NULL and Interface count to zero 0 iii) Scan thro the .txt file and search for the string or regular expression "interface # iv) When a match found in .txt file, check the Interface Number and increment the count for the corresponding entry. Else add new element to the Interface Number list v) If there are no files return to the first directory My o/p is like follows Interface Frequency 123f 3 1232 4

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• How to call Postgres function returning SETOF record?

  - by Peter

  I have written the following function: -- Gets stats for all markets CREATE OR REPLACE FUNCTION GetMarketStats ( ) RETURNS SETOF record AS $$ BEGIN SELECT 'R approved offer' AS Metric, SUM(CASE WHEN M.MarketName = 'A+' AND M.Term = 24 THEN LO.Amount ELSE 0 end) AS MarketAPlus24, SUM(CASE WHEN M.MarketName = 'A+' AND M.Term = 36 THEN LO.Amount ELSE 0 end) AS MarketAPlus36, SUM(CASE WHEN M.MarketName = 'A' AND M.Term = 24 THEN LO.Amount ELSE 0 end) AS MarketA24, SUM(CASE WHEN M.MarketName = 'A' AND M.Term = 36 THEN LO.Amount ELSE 0 end) AS MarketA36, SUM(CASE WHEN M.MarketName = 'B' AND M.Term = 24 THEN LO.Amount ELSE 0 end) AS MarketB24, SUM(CASE WHEN M.MarketName = 'B' AND M.Term = 36 THEN LO.Amount ELSE 0 end) AS MarketB36 FROM "Market" M INNER JOIN "Listing" L ON L.MarketID = M.MarketID INNER JOIN "ListingOffer" LO ON L.ListingID = LO.ListingID; END $$ LANGUAGE plpgsql; And when trying to call it like this... select * from GetMarketStats() AS (Metric VARCHAR(50),MarketAPlus24 INT,MarketAPlus36 INT,MarketA24 INT,MarketA36 INT,MarketB24 INT,MarketB36 INT); I get an error: ERROR: query has no destination for result data HINT: If you want to discard the results of a SELECT, use PERFORM instead. CONTEXT: PL/pgSQL function "getmarketstats" line 2 at SQL statement I don't understand this output. I've tried using perform too, but I thought one only had to use that if the function doesn't return anything.

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• Detecting UITableView scrolling

  - by Xeph

  Hi I've subclassed UITableView (as KRTableView) and implemented the four touch-based methods (touchesBegan, touchesEnded, touchesMoved, and touchesCancelled) so that I can detect when a touch-based event is being handled on a UITableView. Essentially what I need to detect is when the UITableView is scrolling up or down. However, subclassing UITableView and creating the above methods only detects when scrolling or finger movement is occuring within a UITableViewCell, not on the entire UITableView. As soon as my finger is moved onto the next cell, the touch events don't do anything. This is how I'm subclassing UITableView: #import "KRTableView.h" @implementation KRTableView - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesBegan:touches withEvent:event]; NSLog(@"touches began..."); } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesMoved:touches withEvent:event]; NSLog(@"touchesMoved occured"); } - (void)touchesCancelled:(NSSet*)touches withEvent:(UIEvent *)event { [super touchesCancelled:touches withEvent:event]; NSLog(@"touchesCancelled occured"); } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesEnded:touches withEvent:event]; NSLog(@"A tap was detected on KRTableView"); } @end How can I detect when the UITableView is scrolling up or down?

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• Where do you take mocking - immediate dependencies, or do you grow the boundaries...?

  - by Peter Mounce

  So, I'm reasonably new to both unit testing and mocking in C# and .NET; I'm using xUnit.net and Rhino Mocks respectively. I'm a convert, and I'm focussing on writing behaviour specifications, I guess, instead of being purely TDD. Bah, semantics; I want an automated safety net to work above, essentially. A thought struck me though. I get programming against interfaces, and the benefits as far as breaking apart dependencies goes there. Sold. However, in my behaviour verification suite (aka unit tests ;-) ), I'm asserting behaviour one interface at a time. As in, one implementation of an interface at a time, with all of its dependencies mocked out and expectations set up. The approach seems to be that if we verify that a class behaves as it should against its collaborating dependencies, and in turn relies on each of those collaborating dependencies to have signed that same quality contract, we're golden. Seems reasonable enough. Back to the thought, though. Is there any value in semi-integration tests, where a test-fixture is asserting against a unit of concrete implementations that are wired together, and we're testing its internal behaviour against mocked dependencies? I just re-read that and I think I could probably have worded it better. Obviously, there's going to be a certain amount of "well, if it adds value for you, keep doing it", I suppose - but has anyone else thought about doing that, and reaped benefits from it outweighing the costs?

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• javascript function not working in IE 7

  - by JPro

  Hi, Can anyone please tell me how do I make this script run in IE 7? When I run this , nothing happens. <html> <body> <script language="JavaScript"> function moveSelectedOption() { // Fetch references to the <select> elements. var origin = document.getElementById('origin_select'); var target = document.getElementById('target_select'); // Fetch the selected option and clone it. var option = origin.options[origin.selectedIndex]; var copy = option.cloneNode(true); // Add the clone to the target element. target.add(copy, null); } </script> <select id="origin_select" multiple> <option value="A">A</option> <option value="B">B</option> <option value="C">C</option> </select> <select id="target_select" multiple> <option value="C1">C1</option> </select> <button onclick="moveSelectedOption()">Add</button> </body> </html>

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• (EXCEL)VBA Spin button which steps through in an sql databases date time

  - by Gulredy

  I have an sql Database table in MySQL which have lots of rows with varied date time values. For example: 2012-08-21 10:10:00 <-- with these date there are around 12 rows 2012-08-21 15:31:00 <-- with these date there are around 5 rows 2012-08-22 11:40:00 <-- with these date there are around 10 rows 2012-08-22 12:17:00 <-- with these date there are around 9 rows 2012-08-22 12:18:00 <-- with these date there are around 7 rows 2012-08-25 07:21:00 <-- with these date there are around 6 rows If the user clicks on the SpinButton1_SpinUp() or SpinButton1_SpinDown() button then it should do the following: The SpinButton1_SpinUp() button should filter out those data from an sql table which is the next after what we are currently on now. Example: We have currently selected: 2012-08-21 15:31:00. The user hits the SpinUp button then the program selects those date from the database, which is the next higher value like this one: 2012-08-22 11:40:00. So the user hits the SpinUp button the data which is selected in the database will change from those with date: 2012-08-21 15:31:00 to those with date: 2012-08-22 11:40:00 The SpinButton1_SpinDown() will do exactly the reverse of the SpinUp button. When the user hits the SpinDown button the data which is selected in the database will change from those with date: 2012-08-21 15:31:00 to those with date 2012-08-21 10:10:00 So I think the date which we are currently on, should be stored in a variable. But on button hit not every bigger or lower data should be selected in the database, only those which are the closest bigger or the closest lower date. How can I do this? I hope I described my problem understandable. My native language is not english, so misunderstandings can occur! Please ask if you don't understand something! Thank you for reading!

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• Generic unit test scheduling

  - by Raphink

  Hello, I'm (re)writing a program that does generic unit test scheduling. The current program is a mono-threaded Perl program, but I'm willing to modularize it and parallelize the tests. I'm also considering rewriting it in Python. Here is what I need to do: I have a list of tests, with the following attributes: uri: a URI to test (could be HTTP/HTTPS/SSH/local) ; depends: an associative array of tests/values that this test depends on ; join: a list of DB joints to be added when selecting items to process in this test ; depends_db: additional conditions to add to the DB request when selecting items to process in this test. The program builds a dependency tree, beginning with the tests that have no dependencies ; for each test: a list of items is selected from the database using the conditions (results of depending tests, joints and depends_db) ; the list of items is sent to the URI (using POST or stdin) ; the result is retrived as a YAML file listing the state and comments for the test for each tested item ; the results are stored in the DB ; the test returns, allowing depending tests to be performed. the program generates reports (CSV, DB, graphviz) of the performed tests. The primary use of this program currently is to test a fleet of machines against services such as backup, DNS, etc. The tests can then be: - backup: hosted on the backup machine(s), called through HTTP, checks if the machines' backup went well ; - DNS: hosted on the local machine, called via stdin, checks if the machines' fqdn have a valid DNS entry. Does such a tool/module already exist? What would be the best implementation to achieve this (using Perl or Python)?

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• Dynamically created operators

  - by Gero

  I created a program using dev-cpp and wxwidgets which solves a puzzle. The user must fill the operations blocks and the results blocks, and the program will solve it. Im solving it using bruteforce, i generate all non repeated 9 length number combinations using a recursive algorithm. It does it pretty fast. Up to here all is great! But the problem is when my program operates depending the character on the blocks. Its extremely slow (it never gets the answer), because of the chars comparation against +, -, *, etc. Im doing a CASE. Is there some way or some programming language wich allows dinamic creation of operators? So i can define the operator ROW1COL2 to be a +, and the same way to all other operations. I leave a screenshot of the app, so its easier to understand how the puzzle works. http://www.imageshare.web.id/images/9gg5cev8vyokp8rhlot9.png PD: The algorithm works, i tryed it with a trivial puzzle, and solved it in a second.

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• How to make a good programming interview?

  - by luckyluke

  I am doing interviews with from time to time to recruit some not bad people. And I really think I AM NOT doing to correct Job. I work in a company when We have to do a lot o DB programming, .NET programming, Java programming, so we need people who are open minded and not focused on a particular tech. Afterall language is a notation, You have to understand what is going under the hood. I ask people about their project, ask them some coding questions (believe me a SQL question involving a CROSS JOIN is hard), let them write some code, ask them about oo design, ask them how they update their knowledge, and stay up to date, do they have FUN when they code (at least sometimes). Hell I even give them a coding solution for home (3 hours max) to see how they think and code. And yet my hit rate at hiring junior member (those who live over the initial 3 months) is just about 33%. So my question, how do YOU make the good interviews, because I think my hit rate is to low? Do you have any best-practices(should be at least 60-70%)? p.s. And i noticed that: the best programmers are lazy, but motivated, just being lazy is not enough:) But people who write the best code are attentive to details:)

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• How to trace the connection pool in a Java Web application - DBMS_APPLICATION_INFO

  - by Cleiton Garcia

  Hello, I need improve the traceability in a Web Application that usually run on fixed db user. The DBA should have a fast access for the information about the heavy users that are degrading the database. 5 years ago, I implemented a .NET ORM engine which makes a log of user and the server using the DBMS_APPLICATION_INFO package. Using a wrapper above the connection manager with the following code: DBMS_APPLICATION_INFO.SET_MODULE('" + User + " - " + appServerMachine + "',''); Each time that a connection get a connection from the pool, the package is executed to log the information in the V$SESSION. Has anyone discover or implemented a solution for this problem using the Toplink or Hibernate? Is there a default implementation for this problem? I found here a solutions as I implemented 5 years ago, but I'd like to know with anyone have a better solution and integrated with the ORM. http://stackoverflow.com/questions/53379/using-dbmsapplicationinfo-with-jboss My application is above Spring, the DAO are implemented with JPA (using hibernate) and actually running directly in Tomcat, with plans to (next year) migrate to SAP Netwevare Application Server. Thanks.

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• WCF Callback Contract InvalidOperationException: Collection has been modified

  - by mrlane

  We are using a WCF service with a Callback contract. Communication is Asynchronous. The service contract is defined as: [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(ISessionClient),SessionMode = SessionMode.Allowed)] public interface ISessionService With a method: [OperationContract(IsOneWay = true)] void Send(Message message); The callback contract is defined as [ServiceContract] public interface ISessionClient With methods: [OperationContract(IsOneWay = true, AsyncPattern = true)] IAsyncResult BeginSend(Message message, AsyncCallback callback, object state); void EndSend(IAsyncResult result); The implementation of BeginSend and EndSend in the callback channel are as follows: public void Send(ActionMessage actionMessage) { Message message = Message.CreateMessage(_messageVersion, CommsSettings.SOAPActionReceive, actionMessage, _messageSerializer); lock (LO_backChannel) { try { _backChannel.BeginSend(message, OnSendComplete, null); } catch (Exception ex) { _hasFaulted = true; } } } private void OnSendComplete(IAsyncResult asyncResult) { lock (LO_backChannel) { try { _backChannel.EndSend(asyncResult); } catch (Exception ex) { _hasFaulted = true; } } } We are getting an InvalidOperationException: "Collection has been modified" on _backChannel.EndSend(asyncResult) seemingly randomly, and we are really out of ideas about what is causing this. I understand what the exception means, and that concurrency issues are a common cause of such exceptions (hence the locks), but it really doesn't make any sense to me in this situation. The clients of our service are Silverlight 3.0 clients using PollingDuplexHttpBinding which is the only binding available for Silverlight. We have been running fine for ages, but recently have been doing a lot of data binding, and this is when the issues started. Any help with this is appreciated as I am personally stumped at this time.

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• what webserver / mod / technique should I use to serve everything from memory?

  - by reinier

  I've lots of lookuptables from which I'll generate my webresponse. I think IIS with Asp.net enables me to keep static lookuptables in memory which I can use to serve up my responses very fast. Are there however also non .net solutions which can do the same? I've looked at fastcgi, but I think this starts X processes, of which anyone can handle Y requests. But the processes are by definition shielded from eachother. I could configure fastcgi to use just 1 process, but does this have scalability implications? anything using PHP or any other interpreted language won't fly because it is also cgi or fastcgi bound right? I understand memcache could be an option, though this would require another (local) socket connection which I'd rather avoid since everything in memory would be much faster. The solution can work under WIndows or Unix... it doesn't matter too much. The only thing which matters is that there will be a lot of requests (100/sec now and growing to 500/sec in a year), and I want to reduce the amount of webservers needed to process it. The current solution is done using PHP and memcache (and the occasional hit to the SQL server backend). Although it is fast (for php anyway), Apache has real problems when the 50/sec is passed. I've put a bounty on this question since I've not seen enough responses to make a wise choice. At the moment I'm considering either Asp.net or fastcgi with C(++).

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• Persistent warning message about "initWithDelegate"!

  - by RickiG

  Hi This is not an actual Xcode error message, it is a warning that has been haunting me for a long time. I have found no way of removing it and I think I maybe have overstepped some unwritten naming convention rule. If I build a class, most often extending NSObject, whose only purpose is to do some task and report back when it has data, I often give it a convenience constructor like "initWithDelegate". The first time I did this in my current project was for a class called ISWebservice which has a protocol like this: @protocol ISWebserviceDelegate @optional - (void) serviceFailed:(NSError*) error; - (void) serviceSuccess:(NSArray*) data; @required @end Declared in my ISWebservice.h interface, right below my import statements. I have other classes that uses a convenience constructor named "initWithDelegate". E.g. "InternetConnectionLost.h", this class does not however have its methods as optional, there are no @optional @required tags in the declaration, i.e. they are all required. Now my warning pops up every time I instantiate one of these Classes with convenience constructors written later than the ISWebservice, so when utilizing the "InternetConnectionLost" class, even though the entire Class owning the "InternetConnectionLost" object has nothing to do with the "ISWebservice" Class, no imports, methods being called, no nothing, the warning goes: 'ClassOwningInternetConnectionLost' does not implement the 'ISWebserviceDelegate' protocol I does not break anything, crash at runtime or do me any harm, but it has begun to bug me as I near release. Also, because several classes use the "initWithDelegate" constructor naming, I have 18 of these warnings in my build results and I am getting uncertain if I did something wrong, being fairly new at this language. Hope someone can shed a little light on this warning, thank you:)

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• Unittesting aspect-oriented features.

  - by Tomas Brambora

  Hi, I'd like to know what would you propose as the best way to unit test aspect-oriented application features (well, perhaps that's not the best name, but it's the best I was able to come up with :-) ) such as logging or security? These things are sort of omni-present in the application, so how to test them properly? E.g. say that I'm writing a Cherrypy web server in Python. I can use a decorator to check whether the logged-in user has the permission to access a given page. But then I'd need to write a test for every page to see whether it works oK (or more like to see that I had not forgotten to check security perms for that page). This could maybe (emphasis on maybe) be bearable if logging and/or security were implemented during the web server "normal business implementation". However, security and logging usually tend to be added to the app as an afterthough (or maybe that's just my experience, I'm usually given a server and then asked to implement security model :-) ). Any thoughts on this are very welcome. I have currently 'solved' this issue by, well - not testing this at all. Thanks.

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