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• IIS redirect url for virtual directory

  - by Jouni

  Hello, How i can set redirect url for virtual directory in iis 7.0.I have installed lates url rewrite module 2. ? I could explain my problem with exsample. I have website on my iis 7.0 server: www.mysite.com I desided to create virtual directory sales under my site which is pointing to website root directory.Now I need create redirect url for the vdir. The vdir is pointing same virtual root directory as my site root is The big idea is that i can write on browser www.mysite/sales and i will automaticly redirect to url www.mysite.com?productid=200. I tried to make redirect with rewite url for vdir(not website), but I always get this error message : cannot add duplicate colletion entry of type 'rule' with unique key key attribute 'name' set to "test".This happens when i am pointing for virtual vdir and try to add rule. I can add rules to website level,but rules doesn work. I mean url www.mysite/sales gives me follwing error. I know that key is unique I checked it from web.config. This kind of feature was really easy use in IIS 6.0, just point vdir with your mouse and set properties--a redirect to url. Please some one explain what is right way to do it in IIS 7.0

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• Hibernate 1:M relationship ,row order, constant values table and concurrency

  - by EugeneP

  table A and B need to have 1:M relationship a and b are added during application runtime, so A created, then say 4 B's created. Each B instance has to come in order, so that I could later extract them in the same order as I added them. The app will be a web-app running on Tomcat, so 10 instances may work simultaneously. So my question are: 1) How to preserve inserting order, so that I could extract B instances that A references in the same order as I persisted them. That's tricky, because we add to a Collection and then it gets saved (am I right?). So, it depends on how Hibernate saves it, what if it changes the order in what we added instances? I've seen something like LIST instead of SET when describing relationships, is that what I need? 2) How to add a 3-rd column to B so that I could differentiate the instances, something like SEX(M,F,U) in B table. Do I need a special table, or there's and easy way to describe constants in Hibernate. What do you recommend? 3) Talking about concurrency, what methods do you recommend to use? There should be no collisions in the db and as you see, there might easily be some if rows are not inserted (PK added) right where it is invoked without delays ?

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• Good C string libary

  - by chamakits

  Hello all. I recently got inspired to start up a project I've been wanting to code for a while. I want to do it in C, because memory handling is key this application. I was searching around for a good implementation of strings in C, since I know me doing it myself could lead to some messy buffer overflows, and I expect to be dealing with a fairly big amount of strings. I found this article which gives details on each, but they each seem like they have a good amount of cons going for them (don't get me wrong, this article is EXTREMELY helpful, but it still worries me that even if I were to choose one of those, I wouldn't be using the best I can get). I also don't know how up to date the article is, hence my current plea. What I'm looking for is something that may hold a large amount of characters, and simplifies the process of searching through the string. If it allows me to tokenize the string in any way, even better. Also, it should have some pretty good I/O performance. Printing, and formatted printing isn't quite a top priority. I know I shouldn't expect a library to do all the work for me, but was just wandering if there was a well documented string function out there that could save me some time and some work. Any help is greatly appreciated. Thanks in advance! EDIT: I was asked about the license I prefer. Any sort of open source license will do, but preferably GPL (v2 or v3). EDIt2: I found betterString (bstring) library and it looks pretty good. Good documentation, small yet versatile amount of functions, and easy to mix with c strings. Anyone have any good or bad stories about it? The only downside I've read about it is that it lacks Unicode (again, read about this, haven't seen it face to face just yet), but everything else seems pretty good. EDIT3: Also, preferable that its pure C.

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• C#: Hijacking a near relative call

  - by Lex

  Alright, I'm trying to write a vary basic modification to a program NOT written by me. I DO NOT have the source to it. I also do not care if this only works for a single version of the program, so hard coding offsets is feasible. Anyways, I've found the function and where it is called in the compiled program. .text:1901C88F loc_1901C88F: ; CODE XREF: ConnectionThread+1A2j .text:1901C88F ; DATA XREF: .text:off_1901CC64o .text:1901C88F 8B C8 mov ecx, eax ; jumptable 1901C862 case 11 .text:1901C891 8B C6 mov eax, esi .text:1901C893 E8 48 C5 FF FF call ChatEvent According to IDA the full function signature is: char *__usercall ChatEvent<eax>(char *Data<eax>, unsigned int Length<ecx>) I already have all I need to patch the program during runtime, and do whatever other manipulations I need. What I need, is to be able to write a function like so: bool ProcessChat(char *Data, unsigned int Length); char *__usercall HijackFunction(char *Data, unsigned int Length){ if (ProcessChat(Data, Length)) Call OriginalChatEvent(Data, Length); } Get the jist of what I am trying to do? With stdcall function it's easy just replace the 4 byte address with my own function's address. But this is a near relative call, which is.. more annoying. So, anyone have any idea?

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• Some ASP.NET and Access

  - by Fazleh

  Good Day all, I have a big problem but i think its minor for you guys in Stackoverflow. I am creating a web application that has two main parts. The Payment part and Requisition part. It backbone is using access and the script is in ASP.NET. I managed to sort out most of the application. But I have been having a few problems. I have pasted the link to the project in http://www.mediafire.com/download/p09fefreifidud3/Inyatsi.rar so it will be easy for someone to see what I am blabbing about. Now for my problems: The AddRequisition.aspx/AddPayment.aspx: both have a reference number. I wanted it to be unique number(but not a primary key). I wanted it to be in the following format: DDMMYY(TransactionNo)(UserID) eg: 24061101PK. I have tried and tried but have not been able to sort it out. The AmountINWords gets the value from Amount. It converts the Amount into words. Thats not all. It picks what currncy was picked in the CurrencyPaidIn and pust the respective currency inside. eg. 123.45 USD becomes One Hundred and twenty three dollars and forty five cents. I tried using queries but as you will see that went all wrong. Those are the only two things that I cant seem to get my head around. I do know that there are some things that are not conventional ASP.NET and some text boxes are not the right size. I was thinking of sorting out those after I get those two fixed because they are simple to do. I really need some help with this application please. If someone can just have a look at the code and add a few things here and there. Thanks in advance. Faz

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• How to transfer Eclipse workspace and project from Windows to Linux and Mac

  - by Li Ma

  We have a a product developed on Windows for years. The product is composed of one Eclipse workspace and about 20 projects. On Windows, we ask every developer check out projects into d:\dev\product folder, and copy a unified Workspace to d:\dev\prod_workspace. This way, whenever a new machine is set, we simply copy files to the same folder, and we can start working immediately. No We need to move our development environment to Linux and Mac. But there's no D:\ on Unix. And home folder for Linux is mostly like /home/username and /Users/username for Mac. We found Eclipse keeps absolute path in workspace when referring to projects, so simply copy workspace over does not work anymore. Even when we manually create/configure workspace on a Linux machine, it still cannot be copied over to another user, because the absolute path is changed. I guess our goal is to allow easy setup of development environment. Do you have any suggestion to move eclipse workspace around? Thanks! Li

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• syntax for MySQL INSERT with an array of columns

  - by Mike_Laird

  I'm new to PHP and MySQL query construction. I have a processor for a large form. A few fields are required, most fields are user optional. In my case, the HTML ids and the MySQL column names are identical. I've found tutorials about using arrays to convert $_POST into the fields and values for INSERT INTO, but I can't get them working - after many hours. I've stepped back to make a very simple INSERT using arrays and variables, but I'm still stumped. The following line works and INSERTs 5 items into a database with over 100 columns. The first 4 items are strings, the 5th item, monthlyRental is an integer. $query = "INSERT INTO `$table` (country, stateProvince, city3, city3Geocode, monthlyRental) VALUES ( '$country', '$stateProvince', '$city3', '$city3Geocode', '$monthlyRental')"; When I make an array for the fields and use it, as follows: $colsx = array('country,', 'stateProvince,', 'city3,', 'city3Geocode,', 'monthlyRental'); $query = "INSERT INTO `$table` ('$colsx') VALUES ( '$country', '$stateProvince', '$city3', '$city3Geocode', '$monthlyRental')"; I get a MySQL error - check the manual that corresponds to your MySQL server version for the right syntax to use near ''Array') VALUES ( 'US', 'New York', 'Fairport, Monroe County, New York', '(43.09)' at line 1. I get this error whether the array items have commas inside the single quotes or not. I've done a lot of reading and tried many combinations and I can't get it. I want to see the proper syntax on a small scale before I go back to foreach expressions to process $_POST and both the fields and values are arrays. And yes, I know I should use mysql_real_escape_string, but that is an easy later step in the foreach. Lastly, some clues about the syntax for an array of values would be helpful, particularly if it is different from the fields array. I know I need to add a null as the first array item to trigger the MySQL autoincrement id. What else? I'm pretty new, so please be specific.

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• Pair attribute naming in custom configSections

  - by fearofawhackplanet

  I'm trying to store a user list in a config file. I've been looking at DictionarySectionHandler and NameValueSectionHandler. I'm not too sure what the difference between these two is, but anyway, neither of them do exactly what I'd like. You can add a custom config section like so: <configSections> <section name="userAges" type="System.Configuration.DictionarySectionHandler"/> </configSections> <userAges> <add key="userName1" value="10" /> <add key="userName2" value="52" /> <userAges> Which is ok, but actually I'd prefer to be able to write: ... <userAges> <add user="userName1" age="10" /> <add user="userName2" age="52" /> <userAges> Which I feel would make the config file clearer to anyone who needed to add/remove users in future. Is there an easy way to do this?

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• Strategies for testing reactive, asynchronous code

  - by Arne

  I am developing a data-flow oriented domain-specific language. To simplify, let's just look at Operations. Operations have a number of named parameters and can be asked to compute their result using their current state. To decide when an Operation should produce a result, it gets a Decision that is sensitive to which parameter got a value from who. When this Decision decides that it is fulfilled, it emits a Signal using an Observer. An Accessor listens for this Signal and in turn calls the Result method of the Operation in order to multiplex it to the parameters of other Operations. So far, so good, nicely decoupled design, composable and reusable and, depending on the specific Observer used, as asynchronous as you want it to be. Now here's my problem: I would love to start coding actual Tests against this design. But with an asynchronous Observer... how should I know that the whole signal-and-parameters-plumbing worked? Do I need to use time outs while waiting for a Signal in order to say that it was emitted successfully or not? How can I be, formally, sure that the Signal will not be emitted if I just wait a little longer (halting problem? ;-)) And, how can I be sure that the Signal was emitted because it was me who set a parameter, and not another Operation? It might well be that my test comes to early and sees a Signal that was emitted way before my setting a parameter caused a Decision to emit it. Currently, I guess the trivial cases are easy to test, but as soon as I want to test complex many-to-many - situations between operations I must resort to hoping that the design Just Works (tm)...

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• Is there such a thing as a MemberExpression that handles a many-to-many relationship?

  - by Jaxidian

  We're trying to make it easy to write strongly-typed code in all areas of our system, so rather than setting var sortColumn = "FirstName" we'd like to say sortOption = (p => p.FirstName). This works great if the sortOption is of type Expression<Func<Person, object>> (we actually use generics in our code but that doesn't matter). However, we run into problems for many-to-many relationships because this notation breaks down. Consider this simple code: internal class Business { public IQueryable<Address> Addresses { get; set; } public string Name { get; set; } } internal class Address { public State MyState { get; set; } } internal class State { public string Abbreviation { get; set; } public int StateID { get; set; } } Is it possible to have this sort of MemberExpression to identify the StateID column off of a business? Again, the purpose of using this is not to return a StateID object, it's to just identify that property off of that entity (for sorting, filtering, and other purposes). It SEEMS to me that there should be some way to do this, even if it's not quite as pretty as foo = business.Addresses.SomeExtension(a => a.State.StateID);. Is this really possible? If more background is needed, take a look at this old question of mine. We've since updated the code significantly, but this should give you the general detailed idea of the context behind this question.

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• Usage of CRTP in a call chain

  - by fhw72

  In my widget library I'd like to implement some kind of call chain to initialize a user supplied VIEW class which might(!) be derived from another class which adds some additional functionality like this: #include <iostream> template<typename VIEW> struct App { VIEW view; void init() {view.initialize(); } }; template<typename DERIVED> struct SpecializedView { void initialize() { std::cout << "SpecializedView" << std::endl; static_cast<DERIVED*>(this)->initialize(); } }; struct UserView : SpecializedView<UserView> { void initialize() {std::cout << "UserView" << std::endl; } }; int _tmain(int argc, _TCHAR* argv[]) { // Cannot be altered to: App<SpecializedView<UserView> > app; App<UserView> app; app.init(); return 0; } Is it possible to achieve some kind of call chain (if the user supplied VIEW class is derived from "SpecializedView") such that the output will be: console output: SpecializedView UserView Of course it would be easy to instantiate variable app with the type derived from but this code is hidden in the library and should not be alterable. In other words: The library code should only get the user derived type as parameter.

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• Write transparent HTTP Proxy script in PHP

  - by Leo Izen

  Is there an easy forwarding/transparent php proxy script that I can host on my web server? These are my conditions: I'm using free web hosting, so I have pretty much no control over my machine. Otherwise I could use Perl's HTTP::Proxy module. This means no root password. It does run php though. I already have a server running on port 80. What I mean is I would like to put a php script as index.php on my server that will forward all requests. I don't want a script like PHProxy or Glype where I go to the site, then enter a URL. I want a server so I can enter proxy.example.com:80 in Firefox's or IE's or whatever's proxy settings and it will forward all requests to the server. Preferably (though not fatal if not possible) I would like for it to pass on the USER_AGENT environmental variable (That's the browser) instead of setting itself to be the USER_AGENT I can't start a new Daemon. My server won't allow it. Is there a script that will do this? If so, which?

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• I can't seem to figure out type variables mixed with classes.

  - by onmach

  I pretty much understand 3/4 the rest of the language, but every time I dip my feet into using classes in a meaningful way in my code I get permantently entrenched. Why doesn't this extremely simple code work? data Room n = Room n n deriving Show class HasArea a where width :: (Num n) => a -> n instance (Num n) => HasArea (Room n) where width (Room w h) = w So, room width is denoted by ints or maybe floats, I don't want to restrict it at this point. Both the class and the instance restrict the n type to Nums, but it still doesn't like it and I get this error: Couldn't match expected type `n1' against inferred type `n' `n1' is a rigid type variable bound by the type signature for `width' at Dungeon.hs:11:16 `n' is a rigid type variable bound by the instance declaration at Dungeon.hs:13:14 In the expression: w In the definition of `width': width (Room w h) = w In the instance declaration for `HasArea (Room n)' So it tells me the types doesn't match, but it doesn't tell me what types it thinks they are, which would be really helpful. As a side note, is there any easy way to debug an error like this? The only way I know to do it is to randomly change stuff until it works.

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• How can I make my code work in a GUI using Swing in Java?

  - by Razor Shadow

  I'm making a tool that does multiple things, and I'm onto the last feature for now: You type in a date and it tells you what day of the week it would be on that date. So I have two problems here: I can't use I can't use arguments, it doesn't like them On the last line, I can't use jTextArea2.setText(d0); because it doesn't like that either... My code is here: public static void main(String[] args) { int d = Integer.parseInt(args[0]); int m = Integer.parseInt(args[1]); int y = Integer.parseInt(args[2]); int y0 = y - (14 - m) / 12; int x = y0 + y0/4 - y0/100 + y0/400; int m0 = m + 12 * ((14 - m) / 12) - 2; int d0 = (d + x + (31*m0)/12) % 7; System.out.println("Sunday = 0\nMonday = 1\nTuesday = 2\nWednesday = 3\nThursday = 4\nFriday = 5\nSaturday = 6\nThis date is on a:"); System.out.println(d0); Basically, this code was at first for use with the console, and now I want to implement it into a Swing GUI app. I'm only a week into learning Java, so excuse me if the problem is obvious or easy to fix... But can anyone figure out how to work it? Thanks!

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• How to store and synchronize a big list of strings

  - by Joel

  I have a large database table in SQLExpress on Windows, with a particular field of interest 'code'. I have an Apache web server with MySQL on Linux. The web application on the Linux box needs access to the list of all codes. The only thing it will use the list for is checking for the existence of a given code. Having the Linux server call out to the Windows server is impractical as the Windows server is behind a NAT'ed office internet connection, and it may not always be accessible. I have set it so the Windows server will push the list of codes to the web server by means of a simple HTTP POST request. However, at this point I have not implemented the storage of the codes on the Linux box. Should I store them in a MySQL table with a single field 'code'? Then I get fast indexed lookups O(1), however I think synchronization will be an issue - given an updated list of codes, pushed from the Windows box, how would I optimally synchronize the list with the database? TRUNCATE, followed by INSERT? Should I instead store them in a flat file? Then I have O(n) look up time rather than O(1). Additionally an extra constant-time overhead too, as I will be processing the file in Ruby. However, synchronization is easy - simply replace the file.

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• Sort the $_POST variables

  - by Jerry

  Hello guys Might be an easy for you guys. I am trying to sort the $_POST variables that were sent by a form and update the sorted result in mysql. I am not sure how to do it and appreciate it anyone can help me about it. My main.php //I have a loop here. (omitted) //$k will be increased by 1 every time the loop starts, so I will know the total times of the loops //the form will be submitted to update.php echo "<input type='hidden' name='pickTotal' value='".$k."' />"; echo "<input type='hidden' id='point' name='earnedPoint".$k."' value='".$point."' />"; echo "<input type='hidden' id='users' name='userName".$k."' value='".$userPick['user']."' />"; //loop ends My update.php if(isset($_POST['submit'])){ $pickTotal=$_POST['pickTotal']; //get the total loop for ($p=0;$p<=$pickTotal;$p++){ $userToBeUpdated=$_POST['userName'.$p]; $userPoint=$_POST['earnedPoint'.$p]; //sort the $userPoint here. //I need to find out who got the most points //and list user's place. 1st, 2nd, 3rd...etc. //update my mysql } Thanks for any helps.

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• SQL: Getting the full record with the highest count.

  - by sqlnoob

  I'm trying to write sql that produces the desired result from the data below. data: ID Num Opt1 Opt2 Opt3 Count 1 A A E 1 1 A B J 4 2 A A E 9 3 B A F 1 3 B C K 14 4 A A M 3 5 B D G 5 6 C C E 13 6 C C M 1 desired result: ID Num Opt1 Opt2 Opt3 Count 1 A B J 4 2 A A E 9 3 B C K 14 4 A A M 3 5 B D G 5 6 C C E 13 Essentially I want, for each ID Num, the full record with the highest count. I tried doing a group by, but if I group by Opt1, Opt2, Opt3, this doesn't work because it returns the highest count for each (ID Num, Opt2, Opt3, Opt4) combination which is not what I want. If I only group by ID Num, I can get the max for each ID Num but I lose the information as to which (Opt1, Opt2, Opt3) combination gives this count. I feel like I've done this before, but I don't often work with sql and I can't remember how. Is there an easy way to do this?

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• How to break an object into chunks based on some property?

  - by CurlyFro

  public class InvestorMailing { public string To { get; set; } public IEnumerable<string> Attachments { get; set; } public int AttachmentCount { get; set; } public long AttachmentSize { get; set; } } i have an IList<InvestorMailing> mailingList. if the attachment size is greater than x, then i need to split my object into chunks. is there an easy linq-y way to do this? Edited: this is how i'm generating my mailings: var groupedMailings = mailingList.GroupBy(g => g.GroupBy); var investorMailings = groupedMailings.Select( g => new DistinctInvestorMailing { Id = g.Select(x => x.Id).FirstOrDefault(), To = g.Key.Trim(), From = g.Select(x => x.From).FirstOrDefault(), FromName = g.Select(x => x.FromName).FirstOrDefault(), Bcc = g.Select(x => x.Bcc).FirstOrDefault(), DeliveryCode = g.Select(x => x.DeliveryCode).FirstOrDefault(), Subject = g.Select(x => x.Subject).FirstOrDefault(), Body = g.Select(x => x.Body).FirstOrDefault(), CommentsOnStatus = g.Select(x => x.CommentsOnStatus).FirstOrDefault(), Attachments = g.Select(x => x.AttachmentPath), AttachmentCount = g.Select(x => x.AttachmentPath).Count(), AttachmentSize = g.Sum(x => x.AttachmentSize), MailType = g.Select(x => x.MessageType).FirstOrDefault() } ).ToList();

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• EventHandlers saved to databases.

  - by Stacey

  In a database application (using Sql Server right now, in C#, with Entity Framework 4.0) I have a situation where I need to trigger events when some values change. For instance assume a class "Trackable". class Trackable { string Name { get; set; } int Positive { get; set; } int Negative { get; set; } int Total { get; set; } // event OnChanged } Trackable is represented in the database as follows; table Trackables Id | guid name | varchar(32) positive | int negative | int Total is of course, calculated at runtime. When a trackable event changes, I want to inspect its previous value, and then see what it is changing to, and be capable of reacting accordingly. However different trackables need to trigger different events (to avoid a huge, massive cascading switch/if block). If this were just only C# code it would be easy - but they have to be saved to the database. I can't divide up each different trackable into a different table/class, that would be silly - they are all identical, but the event raised is different based on how they are made. So I guess my question is, is there any way to store an event handler in a database such that.. Trackable t1 = new Trackable() { Name = "Trackable1" OnChange += TrackableChangedEventHandler(OnTrackable1Change) } Trackable t2 = new Trackable() { Name = "Trackable2", OnChange += TrackableChangedEventHandler(OnTrackable2Change) }

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• .Net forms - intercepting the Close X event.

  - by Hamish Grubijan

  Hi, this must be a dumb question, but I cannot figure it out. I also cannot use the designer because coders before me managed to throw GUI and logic all in one, so now it is confused. I've got to do it the old school way. I have a Form which can be closed in 3 ways: Close button, File / Close menu, and the X icon. I want them all to do the same thing. Intercepting the button and the menu events is easy. In fact, both are hooked up to an onCloseConfig method. Btw, is there a better name for this method? private void onCloseConfig(object sender, System.EventArgs e) { if (! m_configControl.Modified) { Application.Exit(); // Or should it be this.Close(); } .... // Else present a dialog, ask if they want to save. } So, to intercept the X I tried: this.FormClosing +=new FormClosingEventHandler(this.onCloseConfig); I believe this is what causes an infinite loop. I do not want that :) FormClosed is another option, but it seems too late. I just want to intercept the fact that the X was clicked, not the fact that the form is closing. Please help. Thanks!

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• What's a good way to integrate FB and Twitter into my commenting system (PHP)

  - by Jason

  Hi Guys, There are so many options out there for integration. At the moment I have comments that are posted on my articles, where a user types in their name and the comment. This is then sent to a moderation queue and displayed when approved. I want to acheive this: Comment with facebook login (ie facebook account listed as the name w/ avatar) Comment with twitter login (ie twitter account name listed as the name w/ avatar) Push comment from my website to twitter and to facebook I could go down a few paths as far as I know: Integrate with XFBML, which I don't like because I find it annoying to setup and messy. Integrate facebook comments system, although this can't push to twitter, or allow me to moderate comments from my backend (as far as I can tell i'd have to login under the facebook login for the dev account to moderate the comment) Find a php class that does open auth and integrate with both face book and twitter at once find a pre-created php class Anyone have a solution that will bias: a. easy to integrate b. lightweight c. is free Thanks for your suggestions in advance.

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• Help with 'simple' jQuery question

  - by user318573

  I am trying to get a simple effect working in jQuery, and only have a few hours of experience with it, so have a lot to learn. I managed to get this code working: <script type="text/javascript" > $(document).ready(function() { lastBlock = $("#a1"); maxWidth = 415; minWidth = 75; $("ul li a").hover(function() { $(lastBlock).animate({ width: minWidth + "px" }, { queue: false, duration: 600 }); $(this).animate({ width: maxWidth + "px" }, { queue: false, duration: 600 }); lastBlock = this; }); }); </script> Which gives me exactly what I want, a 6 pane horizontal accordion effect. Each pane however has a 75x75 image on the upper left, which is always visible no matter which pane is active (and it is this image that when hovered over caused the pane to open) - what I want to do is for the image on the selected 'pane', I want to drop the top margin down 10px, and then put it back to 0px when a new one is selected, i.e. so the selected panes image is always 10px lower than the other 5 images. I suspect this should be easy, but not quite grasping the syntax yet. Thanks.

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• Abstract Design Pattern implementation

  - by Pathachiever11

  I started learning design patterns a while ago (only covered facade and abstract so far, but am enjoying it). I'm looking to apply the Abstract pattern to a problem I have. The problem is: Supporting various Database systems using one abstract class and a set of methods and properties, which then the underlying concrete classes (inheriting from abstract class) would be implementing. I have created a DatabaseWrapper abstract class and have create SqlClientData and MSAccessData concrete class that inherit from the DatabaseWrapper. However, I'm still a bit confused about how the pattern goes as far as implementing these classes on the Client. Would I do the following?: DatabaseWrapper sqlClient = new SqlClientData(connectionString); This is what I saw in an example, but that is not what I'm looking for because I want to encapsulate the concrete classes; I only want the Client to use the abstract class. This is so I can support for more database systems in the future with minimal changes to the Client, and creating a new concrete class for the implementations. I'm still learning, so there might be a lot of things wrong here. Please tell me how I can encapsulate all the concrete classes, and if there is anything wrong with my approach. Many Thanks! PS: I'm very excited to get into software architecture, but still am a beginner, so take it easy on me. :)

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• determining the starting speed for an accelerated animation (in flash/actionscript but it's a math question)

  - by vulkanino

  This question burns my brain. I have an object on a plane, but for the sake of simplicity let's work just on a single dimension, thus the object has a starting position xs. I know the ending position xe. The object has to move from starting to ending position with an accelerated (acceleration=a) movement. I know the velocity the object has to have at the ending position (=ve). In my special case the ending speed is zero, but of course I need a general formula. The only unknown is the starting velocity vs. The objects starts with vs in xs and ends with ve in xe, moving along a space x with an acceleration a in a time t. Since I'm working with flash, space is expressed in pixels, time is expressed in frames (but you can reason in terms of seconds, it's easy to convert knowing the frames-per-second). In the animation loop (think onEnterFrame) I compute the new velocity and the new position with (a=0.4 for example): vx *= a (same for vy) x += vx (same for y) I want the entire animation to last, say, 2 seconds, which at 30 fps is 60 frames. Now you know that in 60 frames my object has to move from xs to xe with a constant deceleration so that the ending speed is 0. How do I compute the starting speed vs? Maybe there's a simpler way to do this in Flash, but I am now interested in the math/physics behind this.

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• How to implement a Linked List in Java?

  - by nbarraille

  Hello! I am trying to implement a simple HashTable in Java that uses a Linked List for collision resolution, which is pretty easy to do in C, but I don't know how to do it in Java, as you can't use pointers... First, I know that those structures are already implemented in Java, I'm not planning on using it, just training here... So I created an element, which is a string and a pointer to the next Element: public class Element{ private String s; private Element next; public Element(String s){ this.s = s; this.next = null; } public void setNext(Element e){ this.next = e; } public String getString(){ return this.s; } public Element getNext(){ return this.next; } @Override public String toString() { return "[" + s + "] => "; } } Of course, my HashTable has an array of Element to stock the data: public class CustomHashTable { private Element[] data; Here is my problem: For example I want to implement a method that adds an element AT THE END of the linked List (I know it would have been simpler and more efficient to insert the element at the beginning of the list, but again, this is only for training purposes). How do I do that without pointer? Here is my code (which could work if e was a pointer...): public void add(String s){ int index = hash(s) % data.length; System.out.println("Adding at index: " + index); Element e = this.data[index]; while(e != null){ e = e.getNext(); } e = new Element(s); } Thanks!

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