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  • What are common anti-patterns when using VBA

    - by Ahmad
    I have being coding a lot in VBA lately (maintenance and new code), specifically with regards to Excel automation etc. = macros. Typically most of this has revolved around copy/paste, send some emails, import some files etc. but eventually just ends up as a Big ball of mud As a person who values clean code, I find it very difficult to produce 'decent' code when using VBA. I think that in most cases, this is a direct result of the macro-recorder. Very helpful to get you started, but most times, there are one too many lines of code that achieve the end result. Edit: The code from the macro-recorder is used as a base to get started, but is not used in its entirety in the end result I have already created a common addin that has my commonly used subroutines and some utility classes in an early attempt to enforce some DRYness - so this I think is a step in the right direction. But I feel as if it's a constant square peg, round hole situation. The wiki has an extensive list of common anti-patterns and what scared me the most was how many I have implemented in one way or another. The question Now considering, that my mindset is OO design, what some common anti-patterns and the possible solutions when designing a solution (think of this - how would designing a solution using Excel and VBA be different from say a .net/java/php/.../ etc solution) ; and when doing common tasks like copying data, emailing, data importing, file operations... etc An anti-pattern as defined by Wikipedia is: In software engineering, an anti-pattern (or antipattern) is a pattern that may be commonly used but is ineffective and/or counterproductive in practice

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  • Some questions about slugs in ASP.NET MVC content system

    - by mare
    In my application I'm currently using forms which allow to enter Title and Slug fields. Now I've been struggling with the slugs thing for a while because I can never decide once and for all how to handle them. 1) Make Title and Slug indenpendent Should I allow users to enter both Title and Slug separetely? This is what I had first. I also had an option that if user did not enter the Slug it was derived from the Title. If both were enter, the Slug field took precedence. 2) Derive Slug from Title, when content is inserted that's it for the Slug, no more changes Then, I switched to only Title field and derive Slug from title. While doing it I found out that now I have to change all the forms that allowed user to enter a slug. This way of doing it also prevents users to change Slugs - they can change the Title but it has no effect on the Slug. You can think of it like Slug is uniqued ID. 3) Now I'm thinking again of allowing users to change slug Though I don't think it is all that useful. How many times does the content that someone already added, spent time on writing it, even require a change of either Title or slug? I don't think it is that many times. The biggest problem with the 3rd option is that If I use Slugs as IDs, I need to update the reference all over the place when Slug changes. Or maintain a table that would contain somekind of Slug history. What are you thoughts on these, I hope, valid questions?

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  • Why are floating point values so prolific?

    - by Kibbee
    So, title says it all. Why are floating point values so prolific in computer programming. Due to problems like rounding errors, and not being able to even accurately represent numbers such as 0.1, I really can't see how they got as far as they did. I understand that the computation is faster with floating point numbers, however, I can think of only a few cases that they actually the right data type would be using. If you sat back and think about every time you used a floating point value, how many times did you say, well, some error would be ok, as long as the result was a few microseconds faster. It really makes me think because Jeff was talking about NP completeness, and how heuristics give an answer that is kind of right. And well, computers shouldn't do that. They should give you the answer that is correct. Yet we see floating point values used in many applications where they are completely not valid. What really bugs me, isn't that floating point exists, but that in many languages, there isn't even a viable alternative, non-floating point, decimal value. A lot of programmers when doing financial applications have to fall back to storing the number of cents in an integer field. Which brings with it all kinds of other problems. Why do floats continue to be so prolific, even though they can't represent the real answer, and we expect computers to be accurate? [EDIT] Just to clarify, I was talking about Base 2 floating points, and not base 10 floating points. .Net offers the Decimal data type, which is a base 10 floating point value which offers a much better representation of the numbers we deal with on a daily basis in most computer programs. I find it hard to believe that even modern languages like Java don't support base 10 floating point values, unless you want to move into the realm of things like BigDecimal, which isn't really the right answer either in a lot of situations.

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  • Porting a select loop application to Android with NDK. Design question.

    - by plaisthos
    Hi, I have an network application which uses a select loop like this: bool shutdown=false; while (!shutdown) { [do something] select(...,timeout); } THe main loop cannot work like this in an Android application anymore since the application needs to receive Intents, need to handle GUI, etc. I think I have basically three possibilities: Move the main loop to the java part of the application. Let the loop run in its own thread and somehow communicate from/to java. Screw Android <= 2.3 and use a native activity and use AInputQueue/ALooper instead of select. The first possibility is not easy since java has no select which works on fds. Simply using the select and return after each loop to java is not an elegant possibility either since that requires setting the timeout to something like 20ms to have a good response time in the java part of the program. The second probability sound nicer but I have do some communication between java and the c++/c part of the program. Things that cold work: Using a socket, kind of ugly. using native calls in the "java gui thread" and callback from native in the "c thread". Both threads need to have thread safe implementations but this is managable. I have not explored the third possibility but I think that it is not the way to go. I think I can hack something together which will work but I asking what is the best path to chose.

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  • Is any solution the correct solution?

    - by Eli
    I always think to myself after solving a programming challenge that I have been tied up with for some time, "It works, thats good enough". I don't think this is really the correct mindset, in my opinion and I think I should always be trying to code with the greatest performance. Anyway, with this said, I just tried a ProjectEuler question. Specifically question #2. How could I have improved this solution. I feel like its really verbose. Like I'm passing the previous number in recursion. <?php /* Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ... Find the sum of all the even-valued terms in the sequence which do not exceed four million. */ function fibonacci ( $number, $previous = 1 ) { global $answer; $fibonacci = $number + $previous; if($fibonacci > 4000000) return; if($fibonacci % 2 == 0) { $answer = is_numeric($answer) ? $answer + $fibonacci : $fibonacci; } return fibonacci($fibonacci, $number); } fibonacci(1); echo $answer; ?> Note this isn't homework. I left school hundreds of years ago. I am just feeling bored and going through the Project Euler questions

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  • This is more a matlab/math brain teaser than a question

    - by gd047
    Here is the setup. No assumptions for the values I am using. n=2; % dimension of vectors x and (square) matrix P r=2; % number of x vectors and P matrices x1 = [3;5] x2 = [9;6] x = cat(2,x1,x2) P1 = [6,11;15,-1] P2 = [2,21;-2,3] P(:,1)=P1(:) P(:,2)=P2(:) modePr = [-.4;16] TransPr=[5.9,0.1;20.2,-4.8] pred_modePr = TransPr'*modePr MixPr = TransPr.*(modePr*(pred_modePr.^(-1))') x0 = x*MixPr Then it was time to apply the following formula to get myP , where µij is MixPr. I used this code to get it: myP=zeros(n*n,r); Ptables(:,:,1)=P1; Ptables(:,:,2)=P2; for j=1:r for i = 1:r; temp = MixPr(i,j)*(Ptables(:,:,i) + ... (x(:,i)-x0(:,j))*(x(:,i)-x0(:,j))'); myP(:,j)= myP(:,j) + temp(:); end end Some brilliant guy proposed this formula as another way to produce myP for j=1:r xk1=x(:,j); PP=xk1*xk1'; PP0(:,j)=PP(:); xk1=x0(:,j); PP=xk1*xk1'; PP1(:,j)=PP(:); end myP = (P+PP0)*MixPr-PP1 I tried to formulate the equality between the two methods and seems to be this one. To make things easier, I ignored from both methods the summation of matrix P. where the first part denotes the formula that I used, while the second comes from his code snippet. Do you think this is an obvious equality? If yes, ignore all the above and just try to explain why. I could only start from the LHS, and after some algebra I think I proved it equals to the RHS. However I can't see how did he (or she) think of it in the first place.

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  • Java invokeAndWait of C# Action Delegate

    - by ikurtz
    the issue i mentioned in this post is actually happening because of cross threading GUI issues (i hope). could you help me with Java version of action delegate please? in C# it is done as this inline: this.Invoke(new Action(delegate() {...})); how is this achived in Java? thank you. public class processChatMessage implements Observer { public void update(Observable o, Object obj) { System.out.println("class class class" + obj.getClass()); if (obj instanceof String){ String msg = (String)obj; formatChatHeader(chatHeader.Away, msg); jlStatusBar.setText("Message Received"); // Show chat form setVisibility(); } } } processChatMessage is invoked by a separate thread triggered by receiving new data from a remote node. and i think the error is being produced as it trying to update GUI controls. do you think this is the reason? i ask because im new to Java and C#, but this is what is going on i think. SOLUTION: public class processChatMessage implements Observer { public void update(Observable o, Object obj) { if (obj instanceof String){ final String msg = (String)obj; try { SwingUtilities.invokeAndWait(new Runnable( ) { public void run( ) { formatChatHeader(chatHeader.Away, msg); jlStatusBar.setText("Message Received"); setVisibility(); } }); } catch (InterruptedException e){ } catch (InvocationTargetException e){ } } } }

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  • Sql Server Compact - Schema Management

    - by Richard B
    I've been searching for some time for a good solution to implement the idea of managing schema on a Sql Server Compact 3.5 db. I know of several ways of managing schema on Sql Express/std/enterprise, but Compact Edition doesn't support the necessary tools required to use the same methodology. Any suggestions/tips? I should expand this to say that it is for 100+ clients with wrapperware software. As the system changes, I need to publish update scripts alongside the new binaries to the client. I was looking for a decent method by which to publish this without having to just hand the client a script file and say "Run this in SSMSE". Most clients are not capable of doing such a beast. A buddy of mine disclosed a partial script on how to handle the SQL Server piece of my task, but never worked on Compact Edition... It looks like I'll be on my own for this. What I think that I've decided to do, and it's going to need a "geek week" to accomplish, is that I'm going to write some sort of tool much like how WiX and nAnt works, so that I can just write an overzealous Xml document to handle the work. If I think that it is worthwhile, I'll publish it on CodePlex and/or CodeProject because I've used both sites a bit to gain better understanding of concepts for jobs I've done in the past, and I think it is probably worthwhile to give back a little.

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  • Portlet container like pluto or jetspeed on google app engine?

    - by Patrick Cornelissen
    I am trying to build something "portlet server"-ish on the google app engine. (as open source) I'd like to use the JSR168/286 standards, but I think that the restrictions of the app engine will make it somewhere between tricky and impossible. Has anyone tried to run jetspeed or an application that uses pluto internally on the google app engine? Based on my current knowledge of portlets and the google app engine I'm anticipating these problems: A war file with portlets is from the deployment standpoint more or less a complete webapp (yes, I know that it doesn't really work without a portal server). The war file may contain it's own web.xml etc. This makes deployment on the app engine rather difficult, because the apps are not visible to each other, so all portlet containing archives need to be included in the war file of the deployed "app engine based portal server". The "portlets" are (at least in liferay) started as permanent servlet processes, based on their portlet.xmls and web.xmls which is located in the same spot for every portlet archive that is loaded. I think this may be problematic in the app engine, because everything is in one big "web app", so it may be tricky to access the portlet.xmls from each archive. This prevents a 100% compatibility in my opinion. Is here anyone who has any experience with the combination of portlets and the app engine? Do you think it's feasible to modify jetspeed, pluto or any other portlet container to be able to run it on the app engine?

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  • Empty data problem - data layer or DAL?

    - by luckyluke
    I designing the new App now and giving the following question a lot of thought. I consume a lot of data from the warehouse, and the entities have a lot of dictionary based values (currency, country, tax-whatever data) - dimensions. I cannot be assured though that there won't be nulls. So I am thinking: create an empty value in each of teh dictionaries with special keyID - ie. -1 do the ETL (ssis) do the correct stuff and insert -1 where it needs to let the DAL know that -1 is special (Static const whatever thing) don't care in the code to check for nullness of dictionary entries because THEY will always have a value But maybe I should be thinking: import data AS IS let the DAL do the thinking using empty record Pattern still don't care in the code because business layer will have what it needs from DAL. I think is more of a approach thing but maybe i am missing something important here... What do You think? Am i clear? Please don't confuse it with empty record problem. I do use emptyCustomer think all the time and other defaults too.

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  • How to refactor use of the general Exception?

    - by Colin
    Our code catches the general exception everywhere. Usually it writes the error to a log table in the database and shows a MessageBox to the user to say that the operation requested failed. If there is database interaction, the transaction is rolled back. I have introduced a business logic layer and a data access layer to unravel some of the logic. In the data access layer, I have chosen not to catch anything and I also throw ArgumentNullExceptions and ArgumentOutOfRangeExceptions so that the message passed up the stack does not come straight from the database. In the business logic layer I put a try catch. In the catch I rollback the transaction, do the logging and rethrow. In the presentation layer there is another try catch that displays a MessageBox. I am now thinking about catching a DataException and an ArgumentException instead of an Exception where I know the code only accesses a database. Where the code accesses a web service, then I thought I would create my own "WebServiceException", which would be created in the data access layer whenever an HttpException, WebException or SoapException is thrown. So now, generally I will be catching 2 or 3 exceptions where currently I catch just the general Exception, and I think that seems OK to me. Does anyone wrap exceptions up again to carry the message up to the presentation layer? I think I should probably add a try catch to Main() that catches Exception, attempts to log it, displays an "Application has encountered an error" message and exits the application. So, my question is, does anyone see any holes in my plan? Are there any obvious exceptions that I should be catching or do these ones pretty much cover it (other than file access - I think there is only 1 place where we read-write to a config file).

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  • Viewstate in a .ashx Handler?

    - by Matt Dawdy
    I've got a handler (list.ashx for example) that has a method that retrieves a large dataset, then grabs only the records that will be shown on any given "page" of data. We are allowing the users to do sorting on these results. So, on any given page run, I will be retrieving a dataset that I just got a few seconds/minutes ago, but reordering them, or showing the next page of data, etc. My point is that my dataset really hasn't changed. Normally, the dataset would be stuck into the viewstate of a page, but since I'm using a handler, I don't have that convenience. At least I don't think so. So, what is a common way to store the viewstate associated with a current user's given page when using a handler? Is there a way to take the dataset, encode it somehow and send that back to the user, and then on the next call, pass it back and then rehydrate a dataset from those bits? I don't think Session would be a good place to store it since we might have 1000 users all viewing different datasets of different data, and that could bring the server to its knees. At least I think so. Does anyone have any experience with this kind of situation, and can you give me any advice?

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  • How Can I Find Out *HOW* My Site Was Hacked? How Do I Find Site Vulnerabilities?

    - by Imageree
    One of my custom developed ASP.NET sites was hacked today: "Hacked By Swan (Please Stop Wars !.. )" It is using ASP.NET and SQL Server 2005 and IIS 6.0 and Windows 2003 server. I am not using Ajax and I think I am using stored procedures everywhere I am connecting to the database so I dont think it is SQL injection. I have now removed the write permission on the folders. How can I find out what they did to hack the site and what to do to prevent it from happening again? The server is up to date with all Windows updates. What they have done is uploading 6 files (index.asp, index.html, index.htm,...) to the main directory for the website. What log files should I upload? I have log files for IIS from this folder: c:\winnt\system32\LogFiles\W3SVC1. I am willing to show it to some of you but don't think it is good to post on the Internet. Anyone willing to take a look at it? I have already searched on Google but the only thing I find there are other sites that have been hacked - I haven't been able to see any discussion about it. I know this is not strictly related to programming but this is still an important thing for programmers and a lot of programmers have been hacked like this.

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  • Does Firefox on OS X Lion make use of Full Page Zoom for the touchpad? How to customize behavior?

    - by Steven Lu
    I really like the smooth pinch-zoom of Safari using the touchpad, but the two-finger scroll on Firefox is so much better than the scrolling performance in Safari. So I really like to use Firefox, but then I miss out on two-finger-double-tap to zoom to paragraph width, and the smooth pinch gesture zoom. What I'm wondering is if it is possible to write a Firefox Extension to improve the update rate of the full-page zoom in Firefox that is already functioning via the touchpad pinch gesture. I feel like it is specifically programmed to zoom at certain zoom levels: 100%, 120%, 150% (these are guesses of mine) but I think it would be great if I can get some more control there to make it work more like the zoom functionality in Safari. Also the two-finger-double-tap on a paragraph or element to zoom to it would be really awesome as well. https://developer.mozilla.org/en/Full_page_zoom This seems to indicate (if "full page zoom" is what I think it is) that an extension has the ability to zoom to an arbitrary scale factor, but what remains is to find out if it is possible to obtain or hook the touchpad pinch gesture. Update: I have updated the toolkit.zoomManager.zoomValues option in about:config to include more zoom levels: .3,.5,.67,.8,.9,1,1.01,1.02,1.03,1.04,1.05,1.06,1.07,1.08,1.09,1.1,1.2,1.33,1.5,1.7,2,2.4,3 Notice how I inserted a bunch of entries between 1 and 1.1. But it isn't switching between them any faster (why would it?) so it's less usable than before because of waiting for it to respond fast enough. It's clear that re-rendering the page at a different zoom level requires time and in order for the zoom to be dynamic, some kind of screen capture and scale effect must be performed (which is what Safari does). I guess such a thing is probably doable but I don't think I could pull it off. :-/

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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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  • Tinyurl API Example - Am i doing it right :D

    - by Paul Weber
    Hi ... we use super-long Hashes for the Registration of new Users in our Application. The Problem is that these Hashes break in some Email Clients - making the Links unusable. I tried implementing the Tinyurl - API, with a simple Call, but i think it times out sometimes ... sometimes the mail does not reach the user. I updated the Code, but now the URL is never converted. Is Tinyurl really so slow or am i doing something wrong? (I mean hey, 5 Seconds is much in this Times) Can anybody recommend me a more reliable service? All my Fault, forgot a false in the fopen. But i will leave this sample of code here, because i often see this sample, wich i think does not work very reliable: return file_get_contents('http://tinyurl.com/api-create.php?url='.$u); This is the - i think fully working sample. I would like to hear about Improvements. static function gettinyurl( $url ) { $context = stream_context_create( array( 'http' => array( 'timeout' => 5 // 5 Seconds should be enough ) ) ); // get tiny url via api-create.php $fp = fopen( 'http://tinyurl.com/api-create.php?url='.$url, 'r', $context); // open (read) api-create.php with long url as get parameter if( $fp ) { // check if open was ok $tinyurl = fgets( $fp ); // read response if( $tinyurl && !empty($tinyurl) ) // check if response is ok $url = $tinyurl; // set response as url fclose( $fp ); // close connection } // return return $url; // return (tiny) url }

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  • Debug NAudio MP3 reading difference?

    - by Conrad Albrecht
    My code using NAudio to read one particular MP3 gets different results than several other commercial apps. Specifically: My NAudio-based code finds ~1.4 sec of silence at the beginning of this MP3 before "audible audio" (a drum pickup) starts, whereas other apps (Windows Media Player, RealPlayer, WavePad) show ~2.5 sec of silence before that same drum pickup. The particular MP3 is "Like A Rolling Stone" downloaded from Amazon.com. Tested several other MP3s and none show any similar difference between my code and other apps. Most MP3s don't start with such a long silence so I suspect that's the source of the difference. Debugging problems: I can't actually find a way to even prove that the other apps are right and NAudio/me is wrong, i.e. to compare block-by-block my code's results to a "known good reference implementation"; therefore I can't even precisely define the "error" I need to debug. Since my code reads thousands of samples during those 1.4 sec with no obvious errors, I can't think how to narrow down where/when in the input stream to look for a bug. The heart of the NAudio code is a P/Invoke call to acmStreamConvert(), which is a Windows "black box" call which I can't think how to error-check. Can anyone think of any tricks/techniques to debug this?

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  • How to feature-detect/test for specific jQuery (and Javascript) methods/functions used

    - by Zildjoms
    good day everyone, hope yer all doin awesome am very new to javascript and jquery, and i (think) i have come up with a simple fade-in/out implementation on a site am workin on (check out http://www.s5ent.com/expandjs.html - if you have the time to check it for inefficiency or what that'd be real sweet). i use the following functions/methods/collections and i would like to do a feature test before using them. uhm.. how? or is there a better way to go about this? jQuery $ .fadeIn([duration]) .fadeOut([duration]) .attr(attributeName,value) .append(content) .each(function(index,Element)) .css(propertyName,value) .hover(handlerIn(eventObject),handlerOut(eventObject)) .stop([clearQueue],[jumpToEnd]) .parent() .eq(index) JavaScript setInterval(expression,timeout) clearInterval(timeoutId) setTimeout(expression,timeout) clearTimeout(timeoutId) i tried looking into jquery.support for the jquery ones, but i find myself running into conceptual problems with it, i.e. for fadein/fadeout, i (think i) should test for $.support.opacity, but that would be false in ie whereas ie6+ could still fairly render the fades. also am using jquery 1.2.6 coz that's enough for what i need. the support object is in 1.3. so i'm hoping to avoid dragging-in more unnecessary code if i can. i also worked with browser sniffing, no matter how frowned-upon. but that's also a bigger problem for me because of non-standard ua strings and spoofing and everything else am not aware of. so how do you guys think i should go about this? or should i even? is there a better way to go about making sure that i don't run code that'll eventually break the page? i've set it up to degrade into a css hover when javascript ain't there.. expertise needed. much appreciated, thanks guyz!

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  • Alternative to as3isolib?

    - by tedw4rd
    Hi everyone, I've been working on a Flash game that involves an isometric space. I've been using as3isolib for a while now, and I'm less than impressed with how easy it is to use. Whether I'm approaching it the wrong way or it's just not that great to use is a question for another post. Anyways, I've been thinking of a different way to approach the problem of isometric positions, and I think I've got an idea that might work. Essentially, each object that is to be rendered to the iso-space maintains a 3-coordinate position. Those items are then registered with a camera that projects that 3-coordinate position to a 2-coordinate point on the screen according to the math on this Wikipedia article. Then, the MovieClip is added to the stage (or to the camera's MovieClip, perhaps) at that point, and at a child index of the point's y-value. That way, I figure objects that are closer to the camera will be "above" the objects further away, and will get rendered over them. So my question, then, is two-fold: Do you think this idea will work the way I think it will? Are there any existing 3D matrix/vector packages that I should look at? I know there's a Matrix3 class in Flex 3, but we're not using Flex for this game. Thanks!

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  • Development/runtime Licensing mechanism for a C# class library?

    - by Darryl
    I'm developing a .Net class library (a data provider) and I'm starting to think about how I would handle licensing the library to prospective purchasers. By licensing, I mean the mechanics of trying to prevent my library from being used by those who haven't purchased it, not the software license (i.e., Apache, Gnu, etc). I've never dealt with licensing, and in the past, I've always developed apps, not libraries. I don't want to make things difficult for my customers; know it is not possible to make it ironclad. Just some mechanism that gives me decent protection without making the customer jump through hoops or gnash their teeth. I think the mechanism would check for a valid license when the class is being used in development mode, and not in runtime mode (when the customer's software is released to their customers). I think libraries are typically sold per developer, but I'm not sure how that could be accomplished without making the mechanism odious for my customers; maybe that gets left to the honor system. I Googled this and found many approaches. Ideally, I'd like to do something that is generally accepted and common, the "right" way class libraries are licensed, if that exists, rather than making my customers deal with yet another license mechanism. A firm push in the right direction will be greatly appreciated!

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  • Why does autoboxing in Java allow me to have 3 possible values for a boolean?

    - by John
    Reference: http://java.sun.com/j2se/1.5.0/docs/guide/language/autoboxing.html If your program tries to autounbox null, it will throw a NullPointerException. javac will give you a compile-time error if you try to assign null to a boolean. makes sense. assigning null to a Boolean is a-ok though. also makes sense, i guess. but let's think about the fact that you'll get a NPE when trying to autounbox null. what this means is that you can't safely perform boolean operations on Booleans without null-checking or exception handling. same goes for doing math operations on an Integer. for a long time, i was a fan of autoboxing in java1.5+ because I thought it got java closer to be truly object-oriented. but, after running into this problem last night, i gotta say that i think this sucks. the compiler giving me an error when I'm trying to do stuff with an uninitialized primitive is a good thing. I think I may be misunderstanding the point of autoboxing, but at the same time I will never accept that a boolean should be able to have 3 values. can anyone explain this? what am i not getting?

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  • Realizing program with decision tree logics

    - by Vytas999
    The system realizes a game “Think animal”. Main use case is: 1. System offers user to think about any animal and the system will try to guess it 2. The system starts asking questions from the start of decision tree. Ex., “Question: It has fur?”, and provides possible answers – yes or no. 3. If the user answers Yes, the system proceeds to these steps: a. System tries to guess animal that has that feature, ex. “My guess: Is it bear?” and provides with possible answers – yes or no. b. If the user answer is Yes, the system offers to think off another animal 4. If the user answers is No, the system moves to No node in decision tree and moves to 2 step (and starts from asking from new node). 5. If system runs out of nodes (i.e., empty yes or no node was reached): a. the system announces that it has given up, and ask user to enter: i. What animal he had in mind ii. What is his characteristic feature b. User enters requested data c. The system creates a new node and links it to yes or no of last active node. Where i can get some information and some examples, when implementing decision tree logics in MS SQL Server and C#..? Any information will be usefull. Thanks

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  • Beyond core java

    - by Paul
    Coming to the end of the first year of my CS degree, we've done some Java but just the core stuff; manipulating strings and arrays, inheritance, implementing logic etc. I visit this website daily and I see so much stuff that is beyond me; using frameworks; managing databases etc. It makes me feel like I've just learned the syntax of Java, and there is so much more to do with it. My question is though, how do I get there? I don't think I'm advanced enough to join an open source project, which seems to be suggested often (though I'd love to) and I've looked at other similar questions on here (like this one) but even then I don't think that'd work for me.. firstly, could somebody try give me some commonly used frameworks etc and how and what they are used for? Where would be a good place to start? How did you get started in using the things you do? Or perhaps you think I'm going down the wrong route. Should I learn another language, and just wait until the moment occurs where it's clear what I should be doing? I'm only in the first year of my degree, so far we've lightly covered Haskell and Java, and I've done a little HTML and CSS in my free time. I know that next year we cover python, so perhaps I should just wait till then and see if I prefer that? I feel like I also risk learning something in depth and then never using it... I suppose I'm also asking for personal experiences; was there a point where you felt you'd exceeded the basic grasp of a language (does not necessarily have to be Java related) and reach a more "advanced" level? I guess I'll put subjective tag on this, but really I just want to know how to get beyond the basic understanding of a language.

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  • Password Cracking in 2010 and Beyond

    - by mttr
    I have looked a bit into cryptography and related matters during the last couple of days and am pretty confused by now. I have a question about password strength and am hoping that someone can clear up my confusion by sharing how they think through the following questions. I am becoming obsessed about these things, but need to spend my time otherwise :-) Let's assume we have an eight-digit password that consists of upper and lower-case alphabetic characters, numbers and common symbols. This means we have 8^96 ~= 7.2 quadrillion different possible passwords. As I understand there are at least two approaches to breaking this password. One is to try a brute-force attack where we try to guess each possible combination of characters. How many passwords can modern processors (in 2010, Core i7 Extreme for eg) guess per second (how many instructions does a single password guess take and why)? My guess would be that it takes a modern processor in the order of years to break such a password. Another approach would consist of obtaining a hash of my password as stored by operating systems and then search for collisions. Depending on the type of hash used, we might get the password a lot quicker than by the bruteforce attack. A number of questions about this: Is the assertion in the above sentence correct? How do I think about the time it takes to find collisions for MD4, MD5, etc. hashes? Where does my Snow Leopard store my password hash and what hashing algorithm does it use? And finally, regardless of the strength of file encryption using AES-128/256, the weak link is still my en/decryption password used. Even if breaking the ciphered text would take longer than the lifetime of the universe, a brute-force attack on my de/encryption password (guess password, then try to decrypt file, try next password...), might succeed a lot earlier than the end of the universe. Is that correct? I would be very grateful, if people could have mercy on me and help me think through these probably simple questions, so that I can get back to work.

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  • PHP (CodeIgniter) Pass Object Through Session

    - by FranticPedantic
    I am using PHP5 and CodeIgniter and I am trying to implement a single-sign on feature with facebook (although I don't think that facebook is relevant to the question). I am somewhat of a novice with PHP and definitely one with CodeIgniter, so if you think my approach is just completely off telling me that would be helpful too. So here is in short what I am doing: //Controller 1 $this->load->plugin("facebook"); $facebook = new Facebook(array ( 'appId' => $fbconfig['appid'], 'secret' => $fbconfig['secret'], 'cookie' => true, ) ); $fbsession = $facebook->getSession(); //works fine $this->session->set_userdata('facebook', serialize($facebook); Now I would like to grab that facebook object in a different controller. //Controller 2 $facebook = unserialize($this->session->userdata('facebook')); $fbsession = $facebook->getSession(); Produces the error: Call to undefined method getSession. So I look up more about serialization and think that maybe it just doesn't know what the facebook object's attributes are. So I add in a $this->load->plugin('facebook'); To controller 2 as well and I get a "Cannot redeclare class facebook." I am strongly suspecting that I am misunderstanding sessions here. Do I have to somehow tell PHP what kind of object it is? Thanks for the help.

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