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• How do you make life easier for yourself when developing a really large database

  - by Hannes de Jager

  I am busy developing 2 web based systems with MySql databases and the amount of tables/views/stored routines is really becoming a lot and it is more and more challenging to handle the complexity. Now in programming languages we have namespacing e.g. Java packages, C++ namespaces to partition the software, grouping it together to make things more understandable. Databases on the other hand have more of a flat structure (MySql at least) e.g. tables and stored procedures are on the same level. So one have to be more creative, creating naming conventions, perhaps use more than one database or using tools to visualize things. What methods do you use to ease the pain? To be effective while developing your databases? To not get lost in a sea of tables and fields and stored procs? Feel free to mention tools you use also, but try to restrict it to open source and preferably Linux solutions if thats OK. b.t.w How many tables would a database have to be considered large in terms of design?

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• Getting random record from database with group by

  - by Saif Bechan

  Hello i have a question on picking random entries from a database. I have 4 tables, products, bids and autobids, and users. Products ------- id 20,21,22,23,24(prime_key) price........... etc........... users ------- id(prim_key) name user1,user2,user3 etc bids ------- product_id user_id created autobids -------- user_id product_id Now a multiple users can have an autobid on an product. So for the next bidder I want to select a random user from the autobid table example of the query in language: for each product in the autobid table I want a random user, which is not the last bidder. On product 20 has user1,user2,user3 an autobidding. On product 21 has user1,user2,user3 an autobidding Then I want a resultset that looks for example like this 20 – user2 21 – user3 Just a random user. I tried miximg the GOUP BY (product_id) and making it RAND(), but I just can't get the right values from it. Now I am getting a random user, but all the values that go with it don't match. Can someone please help me construct this query, I am using php and mysql

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• How to parse (infinite) nested object notation?

  - by kyogron

  I am currently breaking my head about transforming this object hash: "food": { "healthy": { "fruits": ['apples', 'bananas', 'oranges'], "vegetables": ['salad', 'onions'] }, "unhealthy": { "fastFood": ['burgers', 'chicken', 'pizza'] } } to something like this: food:healthy:fruits:apples food:healthy:fruits:bananas food:healthy:fruits:oranges food:healthy:vegetables:salad food:healthy:vegetables:onions food:unhealthy:fastFood:burgers food:unhealthy:fastFood:chicken food:unhealthy:fastFood:pizza In theory it actually is just looping through the object while keeping track of the path and the end result. Unfortunately I do not know how I could loop down till I have done all nested. var path; var pointer; function loop(obj) { for (var propertyName in obj) { path = propertyName; pointer = obj[propertyName]; if (pointer typeof === 'object') { loop(pointer); } else { break; } } }; function parse(object) { var collection = []; }; There are two issues which play each out: If I use recurse programming it looses the state of the properties which are already parsed. If I do not use it I cannot parse infinite. Is there some idea how to handle this? Regards

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• Algorithm Question

  - by Ravi

  Hi, I am trying to find a O (n) algorithm for this problem but unable to do so even after spending 3 - 4 hours. The brute force method times out (O (n^2)). I am confused as to how to do it ? Does the solution requires dynamic programming solution ? http://acm.timus.ru/problem.aspx?space=1&num=1794 In short the problem is this: There are some students sitting in circle and each one of them has its own choice as to when he wants to be asked a question from a teacher. The teacher will ask the questions in clockwise order only. For example: 5 3 3 1 5 5 This means that there are 5 students and : 1st student wants to go third 2nd student wants to go third 3rd student wants to go first 4th student wants to go fifth 5th student wants to go fifth. The question is as to where should teacher start asking questions so that maximum number of students will get the turn as they want. For this particular example, the answer is 5 because 3 3 1 5 5 2 3 4 5 1 You can see that by starting at fifth student as 1st, 2 students (3 and 5) are getting the choices as they wanted. For this example the answer is 12th student : 12 5 1 2 3 6 3 8 4 10 3 12 7 because 5 1 2 3 6 3 8 4 10 3 12 7 2 3 4 5 6 7 8 9 10 11 12 1 four students get their choices fulfilled. Thanks Ravi

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• Strange problem with simple multithreading program in Java

  - by Elizabeth

  Hello, I am just starting play with multithreading programming. I would like to my program show alternately character '-' and '+' but it doesn't. My task is to use synchronized keyword. As far I have: class FunnyStringGenerator{ private char c; public FunnyStringGenerator(){ c = '-'; } public synchronized char next(){ if(c == '-'){ c = '+'; } else{ c = '-'; } return c; } } class ThreadToGenerateStr implements Runnable{ FunnyStringGenerator gen; public ThreadToGenerateStr(FunnyStringGenerator fsg){ gen = fsg; } @Override public void run() { for(int i = 0; i < 10; i++){ System.out.print(gen.next()); } } } public class Main{ public static void main(String[] args) throws IOException { FunnyStringGenerator FSG = new FunnyStringGenerator(); ExecutorService exec = Executors.newCachedThreadPool(); for(int i = 0; i < 20; i++){ exec.execute(new ThreadToGenerateStr(FSG)); } } } EDIT: I also testing Thread.sleep in run method instead for loop.

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• What is the minimal licensable source code?

  - by Hernán Eche

  Let's suppose I want to "protect" this code about being used without attribution, patenting it, or through any open source licence... #include<stdio.h> int main (void) { int version=2; printf("\r\n.Hello world, ver:(%d).", version); return 0; } It's a little obvious or just a language definition example.. When a source stop being "trivial, banal, commonplace, obvious", and start to be something that you may claim "rights"? Perhaps it depends on who read it, something that could be great geniality for someone that have never programmed, could be just obvious for an expert. It's easy when watching two sources there are 10000 same lines of code, that's a theft.. but that's not always so obvious. How to measure amount of "ownness", it's about creativity? line numbers? complexity? I can't imagine objetive answers for that, only some patches. For example perhaps the complexity, It's not fair to replace "years of engeneering" with "copy and paste". But is there any objetive index for objetive determination of this subject? (In a funny way I imagine this criterion: If the licence is longer than the code, then there is no owner, just to punish not caring storage space and world resources =P)

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• Problem using unicode in URLs with cgi.PATH_INFO in ColdFusion

  - by Loftx

  Hi there, My ColdFusion (MX7) site has search functionality which appends the search term to the URL e.g. http://www.example.com/search.cfm/searchterm. The problem I'm running into is this is a multilingual site, so the search term may be in another language e.g. ??????? leading to a search URL such as http://www.example.com/search.cfm/??????? The problem is when I come to retrieve the search term from the URL. I'm using cgi.PATH_INFO to retrieve the path of the search page and the search term and extracting the search term from this e.g. /search.cfm/searchterm however, when unicode characters are used in the search they are converted to question marks e.g. /search.cfm/??????. These appear actual question marks, rather than the browser not being able to format unicode characters, or them being mangled on output. I can't find any information about whether ColdFusion supports unicode in the URL, or how I can go about resolving this and getting hold of the complete URL in some way - does anyone have any ideas? Cheers, Tom

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• R plotting multiple histograms on single plot to .pdf as a part of R batch script

  - by Bryce Thomas

  I am writing R scripts which play just a small role in a chain of commands I am executing from a terminal. Basically, I do much of my data manipulation in a Python script and then pipe the output to my R script for plotting. So, from the terminal I execute commands which look something like $python whatever.py | R CMD BATCH do_some_plotting.R. This workflow has been working well for me so far, though I have now reached a point where I want to overlay multiple histograms on the same plot, inspired by this answer to another user's question on Stackoverflow. Inside my R script, my plotting code looks like this: pdf("my_output.pdf") plot(hist(d$original,breaks="FD",prob=TRUE), col=rgb(0,0,1,1/4),xlim=c(0,4000),main="original - This plot is in beta") plot(hist(d$minus_thirty_minutes,breaks="FD",prob=TRUE), col=rgb(1,0,0,1/4),add=T,xlim=c(0,4000),main="minus_thirty_minutes - This plot is in beta") Notably, I am using add=T, which is presumably meant to specify that the second plot should be overlaid on top of the first. When my script has finished, the result I am getting is not two histograms overlaid on top of each other, but rather a 3-page PDF whose 3 individual plots contain the titles: i) Histogram of d$original ii) original - This plot is in beta iii) Histogram of d$minus_thirty_minutes So there's two points here I'm looking to clarify. Firstly, even if the plots weren't overlaid, I would expect just a 2-page PDF, not a 3-page PDF. Can someone explain why I am getting a 3-page PDF? Secondly, is there a correction I can make here somewhere to get just the two histograms plotted, and both of them on the same plot (i.e. 1-page PDF)? The other Stackoverflow question/answer I linked to in the first paragraph did mention that alpha-blending isn't supported on all devices, and so I'm curious whether this has anything to do with it. Either way, it would be good to know if there is a R-based solution to my problem or whether I'm going to have to pipe my data into a different language/plotting engine.

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• how does one _model_ data from relational databases in clojure ?

  - by sandeep

  I have asked this question on twitter as well the #clojure IRC channel, yet got no responses. There have been several articles about Clojure-for-Ruby-programmers, Clojure-for-lisp-programmers.. but what is the missing part is Clojure for ActiveRecord programmers . There have been articles about interacting with MongoDB, Redis, etc. - but these are key value stores at the end of the day. However, coming from a Rails background, we are used to thinking about databases in terms of inheritance - has_many, polymorphic, belongs_to, etc. The few articles about Clojure/Compojure + MySQL (ffclassic) - delve right into sql. Of course, it might be that an ORM induces impedence mismatch, but the fact remains that after thinking like ActiveRecord, it is very difficult to think any other way. I believe that relational DBs, lend themselves very well to the object-oriented paradigm because of them being , essentially, Sets. Stuff like activerecord is very well suited for modelling this data. For e.g. a blog - simply put class Post < ActiveRecord::Base has_many :comments end class Comment < ActiveRecord::Base belongs_to :post end How does one model this in Clojure - which is so strictly anti-OO ? Perhaps the question would have been better if it referred to all functional programming languages, but I am more interested from a Clojure standpoint (and Clojure examples)

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• How do I create a simple Windows form to access a SQL Server database?

  - by NoCatharsis

  I believe this is a very novice question, and if I'm using the wrong forum to ask, please advise. I have a basic understanding of databasing with MS SQL Server, and programming with C++ and C#. I'm trying to teach myself more by setting up my own database with MS SQL Server Express 2008 R2 and accessing it via Windows forms created in C# Express 2010. At this point, I just want to keep it to free or Express dev tools (not necessarily Microsoft though). Anyway, I created a database using the instructions provided here and I set the data types appropriately for each column (no errors in setup at least). Now I'm designing the GUI in C# Express but I've kind of hit a wall as far as the database connection. Is there a simple way to access the database I created locally using C# Express? Can anyone suggest a guide that has all this spelled out already? I am a self-learner so I look forward to teaching myself how to use these applications, but any pointers to start me off in the right direction would be greatly appreciated.

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• how to send on users profile page on selecting username( using json autosuggest script)

  - by I Like PHP

  i m using auto suggest using Ajax Json . now when a user select a user name , i want to send user on the link of that user name my json data is coming in this way { query:'hel', suggestions:["hello world","hell boy ","bac to hell"], data:["2","26","34"] } now what i want that user goes to http://userProfile.php?uid=26 on select username(suppose user select "hell boy") how to do this?? UPDATE: i describe what i m doing step by step i m using a searchbox using jquery ajax, when user write some text on input box , we show (suggest) value regarading their search STEP 1. when user write atleast(2 letter) <input type="text" name="q" id="query" />then a function(below) in invoked in which i send the value written on text box(eg. hell). <script type="text/javascript" language="javascript"> var options, a; jQuery(function(){ options = { serviceUrl:'rpc.php' }; var a = $('#query').autocomplete({ serviceUrl:'rpc.php', minChars:3, delimiter: /(,|;)\s*/, // regex or character maxHeight:400, width:300, zIndex: 9999, deferRequestBy: 0, //miliseconds }); }); </script> STEP 3: on rpc.php, i collect the data and show using JSON my final data come in below format { query:'hell', suggestions:["hello world","hell boy ","bac to hell"], data:["2","26","34"] } where suggestion list having username and data is userid( from user_tables). above data comes in a div (on frontend) where user name displayed in a list STEP 4: now if i select any username using uparrow, downarrow then that name is filled in input box, STEP 5: now what i want that when user select usename then page automatically goes to that user's profile section ( userprofile.php?uid=2)

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• Getting Preferred, Varied Products -- Tough Pseudocode Question

  - by Volomike

  I have a Dallas client who has given me a tough process to work out. I'm seeking your advice. I use PHP, but the language doesn't matter. We can work this out in pseudocode. In a nutshell, this involves showing products on a page based on matching keyword phrases, and using a preferred product provider, but varying this up so that I try to show products from each provider as much as possible when I can. He has 3 product companies: Amazon, eBay, and Overstock. I already have worked out with the API to get products back in an array via a function. He wants to give the user the preference of which one to use primarily -- so a priority number on each. He wants to display anywhere from 1 to 6 products on a page from them. Let's go with 6 for now in this example to start with. Let's assume Amazon first, then eBay, then Overstock as far as priority. He wants me to attempt to take a keyword phrase and find relevant products (all the keywords found in product title) from Amazon, eBay, and Overstock. If we find 1 product from each provider, he wants me to only display one product from each. But if we run out of a particular provider with a matching product, I start over again and grab another product from another provider until we reach 6 products. If there just aren't 6 relevant products, then I do the best I can -- even if I only display one product. If no relevant products, then I don't display anything.

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• How do common web frameworks (Django, Rails, Symfony, etc) handle multiple instances of the same plu

  - by Steven Wei

  Do any of the popular web frameworks solve this problem well? Here's an example: suppose you're running one of these web frameworks and you want to install a blog plugin. Except instead of a single blog, you need to run two separate instances of the blog plugin, and you want to keep them segregated. Or say you want to install multiple instances of a user authentication plugin, because you want to segregate your administrative users from your customer user accounts. Or say you want to install multiple instances of a wiki plugin for different parts of your site, or multiple instances of a comments plugin, or whatever else. It seems to me that at the basic level, each instance of plugin would need to be able to configured with a different set of database tables, and would need to be 'installed' at a different URL path. My experience is mostly with Django and Symfony, and I haven't seen a clean solution to this problem in either of them. They both tend to assume that each plugin (or app, in Django's case) is only ever going to be installed once. I'm curious if the Rails folks have figured out a clean solution to this problem, or any other framework authors (in any language). And if you were going to design a solution to this problem, what would it look like?

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• Why can't I simply copy installed Perl modules to other machines?

  - by pistacchio

  Being very new to Perl but not to dynamic languages, I'm a bit surprised at how not straight forward the manage of modules is. Sure, cpan X does theoretically work, but I'm working on the same project from three different machines and OSs (at work, at home, testing in an external environment). At work (Windows 7) I have problem using cpan because of our firewall that makes ftp unusable At home (Mac OS X) it does work In the external environment (Linux CentOs) it worked after hours because I don't have root access and I had to configure cpan to operate as a non-root user I've tried on another server where I have an access. If the previous external environment is a VPS and so I have a shell access, this other one is a cheap shared hosting where I have no way to install new modules other than the ones pre-installed At the moment I still can't install Template under Windows. I've seen that as an alternative I could compile it and I've also tried ActiveState's PPM but the module is not existent there. Now, my perplexity is about Perl being a dynamic language. I've had all these kind of problems while working, for example, with C where I had to compile all the libraries for all the platform, but I thought that with Perl the approach would have been very similar to Python's or PHP's where in 90% of the cases copying the module in a directory and importing it simply works. So, my question: if Perl's modules are written in Perl, why the copy/paste approach will not work? If some (or some part) of the modules have to be compiled, how to see in CPAN if a module is Perl-only or it relies upon compiled libraries? Isn't there a way to download the module (tar, zip...) and use cpan to deploy it? This would solve my problem under Windows.

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• Developing Job References

  - by Joe Smith

  How do you develop references for jobs? I have 6 years of programming experience spanning two jobs, but sadly I don't have a lot of people I can draw on as references. It's been several years since I left my last job, which was at a small company, and I've lost touch with the few people I knew there. I now work at another small company. I think I've gone as far as I can in my current position, and would like to look for greener pastures, but I can't exactly use my current boss as a reference, even though I have a very good repore with him. I'm sure he'd make a great reference down the road, but I'm afraid I'd insult him or jeopardize my current job by mentioning that I'm thinking of leaving and would like him to help me. I've applied to some jobs, and I have gotten several replies like, "Oh, you're exactly what we're looking for. Send us a couple references and we'll schedule an interview. Oh, no references? You must be a psychopath, nevermind." I've tried doing some small freelance work on the side, just so I can have a contact who can vouch for my work, but the competition for even small projects is pretty fierce and I can rarely devote adequate time to freelancing while holding a full time job. In addition, I often encounter a Catch-22 where a lot of freelancing jobs also require references. So how do programmers maintain existing references and develop new ones, especially while holding a full time job?

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• How do I attach a link (to a View) to an image in ASP.NET MVC?

  - by Ryan Pitts

  Ok, so here is my situation. I am creating a web application using ASP.NET MVC 2 using the C# language. I have programmed in HTML, CSS, and PHP for several years and I am very new to ASP.NET. The part that I am having trouble with is the image gallery. The setup: I have a link on the navigation bar that goes to a "Galleries" page. This page will show a list of galleries. Each gallery has a title, an image, and a description. All of this information is pulled from an XML file. I'm using the XML file like a database. I wanted to use this method so that i could easily update the list of galleries and have the updated XML file automatically be reflected by the website. Now, the galleries should link to an "Images" page. This page will display a list of images within the gallery based on what gallery was selected. This page will also pull from an XML file. The problem: I cannot seem to attach a dynamic link to the image? I am also stuck and not sure how to get the correct View to display. I know I need to do something with the controllers and models, right? I have some code if needed? I would greatly appreciate any help or direction for this! Thanks!

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• Does/Will autofac's ASP.NET integration support PreInit or Init events?

  - by David Rubin

  I see from poking around in the 1.4.4 source that Autofac's ASP.NET integration (via Autofac.Integration.Web) peforms injection of properties on the Page as part of the HttpContext.PreRequestHandlerExecute event handling, but that the page's child controls don't get their properties injected until Page.PreLoad. What this means, though is that the injected properties of child controls are unavailable for use in the OnInit event handler. For example, this works fine: HelloWorld.aspx: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="HelloWorld.aspx.cs" Inherits="HelloWorld" %> <html> <body> <asp:Label runat="server" id="lblMsg" OnInit="HandleInit"/> </body> </html> HelloWorld.aspx.cs: ... protected void HandleInit() { lblMsg.Text = _msgProvider.GetMessage(); } public IMsgProvider _msgProvider { private get; set; } // <-- Injected But changing the HelloWorld Page to a UserControl (.acsx) and putting the UserControl in another page doesn't work because _msgProvider isn't injected early enough. Is there a way to make Autofac inject properties of child controls earlier? Or is this something that can be addressed in a future build? Thanks!

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• FragmentActivity cannot be resolve to a type

  - by Pratik

  I am starting learning for android tablet programming and I am able to updated my Eclipse as well as all new sdk for android. I have start testing application from this blog while at extending the FragmentActivity getting this error I have google it but not getting any solution. My project was created with 3.0 version having 11 level, all other packages are successfully used in the code but only this FragmentActivity was not able to resolve. Am I missing any library or any thing? My code public class Testing_newActivity extends FragmentActivity { // here the FragmentActivity getting error package not found for import /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //setContentView(R.layout.main); if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) { // If the screen is now in landscape mode, we can show the // dialog in-line so we don't need this activity. finish(); return; } if (savedInstanceState == null) { // During initial setup, plug in the details fragment. DetailsFragment details = new DetailsFragment(); details.setArguments(getIntent().getExtras()); getSupportFragmentManager().beginTransaction().add( android.R.id.content, details).commit(); } } } android manifest file <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.searce.testingnew" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="11" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <activity android:label="@string/app_name" android:name=".Testing_newActivity" > <intent-filter > <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>

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• Python modules not updating after restarting the main module.

  - by Ian

  I've recently come back to a project having had to stop for about 6 months, and after reinstalling my operating system and coming back to it I'm having all kinds of crazy things happen. I made sure to install the same version(2.6) of python that I was using before. It started by giving me strange tkinter error that I hadn't had trouble with before, the program is relatively simple and the 2 or 3 bugs that were left when i quit, I had documented and weren't related to the interface. Things got even weirder when the same error would pop up even after I had removed the offending section of code. In fact, the traceback pointed to a line that didn't even exist in the module it was referencing, eg: line 262 when the module was only 200 lines long. After just starting a completely new file for the main module and copy/pasting it finally recognized that the offending code was gone and I stopped getting the error only to find that any updates to the code I made in another module didn't show up when I restarted the program through the shell. (I didn't forget to save.) After fiddling with this, of course, the old interface error came back, only in a different section of code that had been working previously. In fact, if I revert back to the files I had six months ago, the program works fine. As soon as I change anything in the main module, however, the interface bug comes back. Here's the original error: Exception in Tkinter callback Traceback (most recent call last): File "C:\Python26\lib\lib-tk\Tkinter.py", line 1410, in __call__ return self.func(*args) File "C:\PyStuff\interface.py", line 202, in dispOne __main__.top.destroy() File "C:\Python26\lib\lib-tk\Tkinter.py", line 1938, in destroy self.tk.call('destroy', self._w) TclError: can't invoke "destroy" command: application has been destroyed I'm guessing something else is going on here other than my own poor programming. Anyone have any ideas?

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• Encapsulating user input of data for a class (C++)

  - by Dr. Monkey

  For an assignment I've made a simple C++ program that uses a superclass (Student) and two subclasses (CourseStudent and ResearchStudent) to store a list of students and print out their details, with different details shown for the two different types of students (using overriding of the display() method from Student). My question is about how the program collects input from the user of things like the student name, ID number, unit and fee information (for a course student) and research information (for research students): My implementation has the prompting for user input and the collecting of that input handled within the classes themselves. The reasoning behind this was that each class knows what kind of input it needs, so it makes sense to me to have it know how to ask for it (given an ostream through which to ask and an istream to collect the input from). My lecturer says that the prompting and input should all be handled in the main program, which seems to me somewhat messier, and would make it trickier to extend the program to handle different types of students. I am considering, as a compromise, to make a helper class that handles the prompting and collection of user input for each type of Student, which could then be called on by the main program. The advantage of this would be that the student classes don't have as much in them (so they're cleaner), but also they can be bundled with the helper classes if the input functionality is required. This also means more classes of Student could be added without having to make major changes to the main program, as long as helper classes are provided for these new classes. Also the helper class could be swapped for an alternative language version without having to make any changes to the class itself. What are the major advantages and disadvantages of the three different options for user input (fully encapsulated, helper class or in the main program)?

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• jQuery - Unchecking checkboxes that act like radio buttons

  - by Cecil

  Hey All, I have the following jQuery code to make my checkboxes act like radio buttons, so that only 1 of the 3 can be checked at a time. <script type="text/javascript" language="javascript"> $(document).ready(function() { $("#testing input:checkbox").change(function(){ var checkname = $(this).attr("name"); $("input:checkbox[name='" + checkname + "']").removeAttr("checked"); this.checked = true; }); }); </script> The checkboxes are layed out like the following: <input type="checkbox" id="testing" name="testing" value="B"> <input type="checkbox" id="testing" name="testing" value="I"> <input type="checkbox" id="testing" name="testing" value="A"> This works exactly how i want it to work, not a problem, except once i click one of the 3, i cant unclick it so that none of them are checked, this is what i want to happen, so along with being only able to click one at a time, im able to uncheck them completely. Any help would be grand :)

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• Shared Memory and Process Sempahores (IPC)

  - by fsdfa

  This is an extract from Advanced Liniux Programming: Semaphores continue to exist even after all processes using them have terminated. The last process to use a semaphore set must explicitly remove it to ensure that the operating system does not run out of semaphores.To do so, invoke semctl with the semaphore identifier, the number of semaphores in the set, IPC_RMID as the third argument, and any union semun value as the fourth argument (which is ignored).The effective user ID of the calling process must match that of the semaphore’s allocator (or the caller must be root). Unlike shared memory segments, removing a semaphore set causes Linux to deallocate immediately. If a process allocate a shared memory, and many process use it and never set to delete it (with shmctl), if all them terminate, then the shared page continues being available. (We can see this with ipcs). If some process did the shmctl, then when the last process deattached, then the system will deallocate the shared memory. So far so good (I guess, if not, correct me). What I dont understand from that quote I did, is that first it say: "Semaphores continue to exist even after all processes using them have terminated." and then: "Unlike shared memory segments, removing a semaphore set causes Linux to deallocate immediately."

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• Using WIndows PowerShell 1.0 or 2.0 to evaluate performance of executable files.

  - by Andry

  Hello! I am writing a simple script on Windows PowerShell in order to evaluate performance of executable files. The important hypothesisi is the following: I have an executable file, it can be an application written in any possible language (.net and not, Viual-Prolog, C++, C, everything that can be compiled as an .exe file). I want to profile it getting execution times. I did this: Function Time-It { Param ([string]$ProgramPath, [string]$Arguments) $Watch = New-Object System.Diagnostics.Stopwatch $NsecPerTick = (1000 * 1000 * 1000) / [System.Diagnostics.Stopwatch]::Frequency Write-Output "Stopwatch created! NSecPerTick = $NsecPerTick" $Watch.Start() # Starts the timer [System.Diagnostics.Process]::Start($ProgramPath, $Arguments) $Watch.Stop() # Stops the timer # Collectiong timings $Ticks = $Watch.ElapsedTicks $NSecs = $Watch.ElapsedTicks * $NsecPerTick Write-Output "Program executed: time is: $Nsecs ns ($Ticks ticks)" } This function uses stopwatch. Well, the functoin accepts a program path, the stopwatch is started, the program run and the stopwatch then stopped. Problem: the System.Diagnostics.Process.Start is asynchronous and the next instruction (watch stopped) is not executed when the application finishes. A new process is created... I need to stop the timer once the program ends. I thought about the Process class, thicking it held some info regarding the execution times... not lucky... How to solve this?

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• create jquery array to use as options

  - by SoulieBaby

  Hi all, I'm sure this is really simple, but I can't seem to get it working. I have a "time" select list, which has a number as "rel" attached to each option. If the user changes the time select, I want a new list of options to display depending on what is selected. If that makes sense? Here's my first select: <select name="time" id="time"> <option value="7:00am" rel="10">7:00am</option> <option value="12:30pm" rel="16">12:30pm</option> </select> If the user selects 7:00am, I want a new option list (using jquery) to give options from 1 - 10. Like this: <select name="quantity" id="quantity"> <option value="1">1</option> <option value="2">2</option> <option value="3">3</option> ............................ <option value="10">10</option> </select> Here's what I have so far... <script type="text/javascript" language="javascript"> jQuery("#time").change(function(){ var positions = jQuery("#time :selected").attr("rel"); //this grabs the rel from time //this is where it should create a list of options to append(??) to the select list.. jQuery("#showQuantity").show(); //this shows the hidden field for quantity }); </script> I hope it makes sense, but I'm stuck on it. Thank you in advance :)

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• Midiplayer stops playing sounds after 16 notes.

  - by user349673

  Hi. I am currently programming a Piano Keyboard editor, much like the one you can find in Cubase, Logic, Reason etc.. I have this big grid, double array new int [13][9], which makes it 13 rows, 9 columns. The first column [0-12][0] is the Keyboard, at the top there's "high C" (midi note 72) and at the bottom there's "low C" (midi note 60). That column is an array of JButtons and when you press for example "low C", note 60 is being played by the Synthesizer. I've gotten this to work pretty OK as for now, but one problem I have is that I can only play 16 notes in a row, then it's like the Synthesizer shuts down or something. Do you guys have ANY idea of what the problem is? A bit of the code: import java.awt.*; import javax.swing.*; import java.awt.event.*; import java.util.*; import javax.sound.midi.*; actionPerformed(ActionEvent ae){ for(int i = 0; i<13; i++){ if(o== instr[i]){//instr is the button array SpelaTangent(i); } } } public void SpelaTangent(int tangent){ int [] klaviatur = new int[13]; for(int i = 0; i<13; i++){ klaviatur[i] = (72-i); } try { Synthesizer synth = MidiSystem.getSynthesizer(); synth.open(); final MidiChannel[] mc = synth.getChannels(); Instrument[] instrument = synth.getDefaultSoundbank().getInstruments(); synth.loadInstrument(instrument[1]); mc[0].noteOn(klaviatur[tangent],350); mc[0].noteOff(klaviatur[tangent],350); } catch (MidiUnavailableException e) {} } Help is very much appreciated!

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