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• Masters in Computer Science

  - by reko

  Hi, My name is Gautam. I come from India. I am extremely passionate about Web Development.. I like to build web applications all the time.. Can I make this web application building a full time profession? I have just graduated from bachelors... Is there a Master of Computer Science in Web Development? Can I choose Masters in Web Development? Is it a bad choice? Is there a course very close to it Web Development that I can choose? Should I just keep Web Development as a part time thing to do?? Could you please let me know any good universities which offer this course/ close to this course for Spring 2010? Please advice on what I should do because my mind keeps throwing millions of questions on what I should do and my only hope is STACKOVERFLOW helps me as it always does to solve problems.. Looking forward for your reply.. Thanks in advance Regards, Gautam

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• How do I read text from a serial port?

  - by user2164

  I am trying to read data off of a Windows serial port through Java. I have the javax.comm libraries and am able to get some data but not correct data. When I read the port into a byte array and convert it to text I get a series of characters but no real text string. I have tried to specify the byte array as being both "UTF-8" and "US-ASCII". Does anyone know how to get real text out of this? Here is my code: while (inputStream.available() > 0) { int numBytes = inputStream.read(readBuffer); System.out.println("Reading from " + portId.getName() + ": "); System.out.println("Read " + numBytes + " bytes"); } System.out.println(new String(readBuffer)); System.out.println(new String(readBuffer, "UTF-8")); System.out.println(new String(readBuffer, "US-ASCII")); the output of the first three lines will not let me copy and paste (I assume because they are not normal characters). Here is the output of the Hex: 78786000e67e9e60061e8606781e66e0869e98e086f89898861878809e1e9880 I am reading from a Hollux GPS device which does output in string format. I know this for sure because I did it through C#. The settings that I am using for communication which I know are right from the work in the C# app are: Baud Rate: 9600 Databits: 8 Stop bit: 1 parity: none

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• Objective-C: How to access methods in other classes

  - by Adam

  I have what I know is a simple question, but after many searches in books and on the Internet, I can't seem to come up with a solution. I have a standard iPhone project that contains, among other things, a ViewController. My app works just fine at this point. I now want to create a generic class (extending NSObject) that will have some basic utility methods. Let's call this class Util.m (along with the associated .h file). I create the Util class (and .h file) in my project, and now I want to access the methods contained in that class class from my ViewController. Here's an example of a simple version of Util.h #import <Foundation/Foundation.h> @interface Util : NSObject { } - (void)myMethod; @end Then the Util.m file would look something like this: #import "Util.h" @implementation Util - (void)myMethod { NSLog(@"myMethod Called"); } @end Now that my Util class is created, I want to call the "myMethod" method from my ViewController. In my ViewController's .h file, I do the following: #import "Util.h" @interface MyViewController : UIViewController { Util *utils; } @property (assign) Util *utils; @end Finally, in the ViewController.m, I do the following: #import "Util.h" @implementation MyViewController @synthesize utils; - (void)viewDidLoad { [super viewDidLoad]; utils.myMethod; //this doesn't work [utils myMethod]; //this doesn't work either NSLog(@"utils = %@", utils); //in the console, this prints "utils = (null)" } What am I doing wrong? I'd like to not only be able to directly reference other classes/methods in a simple util class like this, but I'd also like to directly reference other ViewControllers and their properties and methods as well. I'm stumped! Please Help.

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• Flash/Flex sending XML to Rails App

  - by bdicasa

  I'm trying to send some XML to a rails app in Flex. I'm using the URLRequest and URLLoader objects. However, I'm having trouble determining how to send the XML and _method parameter to the rails app using these flash objects. Below is how I'm currently trying to achieve this. var request:URLRequest = new URLRequest(); request.method = URLRequestMethod.POST; request.data = new Object(); request.data.xml = Blog.xml.toXMLString(); request.contentType = "text/xml"; var loader:URLLoader = new URLLoader(); loader.addEventListener(Event.COMPLETE, saveCompleteHandler); var saveUrl:String = ""; saveUrl = BASE_URL; if (Blog.isNewBlog) { // Set the rails REST method. request.data._method = "POST"; saveUrl += "blogs.xml"; } else { // Set the rails REST method. request.data._method = "PUT"; saveUrl += "blogs/" + Blog.id.toString() + ".xml"; } request.url = saveUrl; //trace(request.data.toString()); loader.load(request); However the only data that is getting sent to the server is [Object object]. If some one could let me know where I'm going wrong I'd greatly appreciate it. Thanks.

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• NHibernate Child items query using Parent Id

  - by thorkia

  So I have a set up similar to this questions: Parent Child Setup Everything works great when saving the parent and the children. However, I seem to have a problem when selecting the children. I can't seem to get all the children with a specific parent. This fails with: NHibernate.QueryException: could not resolve property: ParentEntity_id of: Test.Data.ChildEntity Here is my code: public IEnumerable<ChildEntity> GetByParent(ParentEntity parent) { using (ISession session = OrmHelper.OpenSession()) { return session.CreateCriteria<ChildEntity>().Add(Restrictions.Eq("ParentEntity_id ", parent.Id)).List<ChildEntity>(); } } Any help in building a proper function to get all the items would be appreciated. Oh, I am using Fluent NHibernate to construct the mappings - version 1 RTM and NHibernate 2.1.2 GA If you need more information, let me know. As per you request, my fluent mappings: public ParentEntityMap() { Id(x => x.Id); Map(x => x.Name); Map(x => x.Code).UniqueKey("ukCode"); HasMany(x => x.ChildEntity).LazyLoad() .Inverse().Cascade.SaveUpdate(); } public ChildEntityMap() { Id(x => x.Id); Map(x => x.Amount); Map(x => x.LogTime); References(x => x.ParentEntity); } That maps to the following 2 tables: CREATE TABLE "ParentEntity" ( Id integer, Name TEXT, Code TEXT, primary key (Id), unique (Code) ) CREATE TABLE "ChildEntity" ( Id integer, Amount NUMERIC, LogTime DATETIME, ParentEntity_id INTEGER, primary key (Id) ) The data store in SQLite.

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• Django: Overriding the save() method: how do I call the delete() method of a child class

  - by Patti

  The setup = I have this class, Transcript: class Transcript(models.Model): body = models.TextField('Body') doPagination = models.BooleanField('Paginate') numPages = models.PositiveIntegerField('Number of Pages') and this class, TranscriptPages(models.Model): class TranscriptPages(models.Model): transcript = models.ForeignKey(Transcript) order = models.PositiveIntegerField('Order') content = models.TextField('Page Content', null=True, blank=True) The Admin behavior I’m trying to create is to let a user populate Transcript.body with the entire contents of a long document and, if they set Transcript.doPagination = True and save the Transcript admin, I will automatically split the body into n Transcript pages. In the admin, TranscriptPages is a StackedInline of the Transcript Admin. To do this I’m overridding Transcript’s save method: def save(self): if self.doPagination: #do stuff super(Transcript, self).save() else: super(Transcript, self).save() The problem = When Transcript.doPagination is True, I want to manually delete all of the TranscriptPages that reference this Transcript so I can then create them again from scratch. So, I thought this would work: #do stuff TranscriptPages.objects.filter(transcript__id=self.id).delete() super(Transcript, self).save() but when I try I get this error: Exception Type: ValidationError Exception Value: [u'Select a valid choice. That choice is not one of the available choices.'] ... and this is the last thing in the stack trace before the exception is raised: .../django/forms/models.py in save_existing_objects pk_value = form.fields[pk_name].clean(raw_pk_value) Other attempts to fix: t = self.transcriptpages_set.all().delete() (where self = Transcript from the save() method) looping over t (above) and deleting each item individually making a post_save signal on TranscriptPages that calls the delete method Any ideas? How does the Admin do it? UPDATE: Every once in a while as I'm playing around with the code I can get a different error (below), but then it just goes away and I can't replicate it again... until the next random time. Exception Type: MultiValueDictKeyError Exception Value: "Key 'transcriptpages_set-0-id' not found in " Exception Location: .../django/utils/datastructures.py in getitem, line 203 and the last lines from the trace: .../django/forms/models.py in _construct_form form = super(BaseInlineFormSet, self)._construct_form(i, **kwargs) .../django/utils/datastructures.py in getitem pk = self.data[pk_key]

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• Java - How to detect that the internet connection has got disconnected through a java desktop applic

  - by Yatendra Goel

  I am developing a Java Desktop Application that access internet. It is a multi-threaded application, each thread do the same work (means each thread is an instance of same Thread class). Now, as all the threads need internet connection to be active, there should be some mechanism that detects whether an internet connection is active or not. Q1. How to detect whether the internet connection is active or not? Q2. Where to implement this internet-status-check-mechanism code? Should I start a separate thread for checking internet status regularly and notifies all the threads when the status changes from one state to another? Or should I let each thread check for the internet-status itself? Q3. This issue should be a very common issue as every application accessing an internet should deal with this problem. So how other developers usually deal with this problem? Q4. If you could give me a reference to a good demo application that addresses this issue then it would greatly help me.

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• RegularExpression-esque search matching Objects in List

  - by Pindatjuh

  I'm currently working on an implementation of the following idea, and I was wondering if there is any literature on this subject. Working with Java, but the principle applies on any language with a decent type-system, I like to implement: matching Objects from a List using a RegularExpression-esque search: So let's say I have a List containing List<Object> x = new ArrayList<Object>(); x.add(new Object()); x.add("Hello World"); x.add("Second String"); x.add(5); // Integer (auto-boxing) x.add(6); // Integer Then I create a "Regular Expression" (not working with a stream of characters, but working with a stream of Objects), and instead of character-classes, I use type-system properties: [String][Integer] And this would match one sublist: {Match["Second String", 5]}. The expression: [String:length()<15] Will match two sublist (each of length 1) containing a String which instance is passing the expression instance.length() < 5: {Match["Hello World"],Match["Second String"]}. [Object][Object] Matches any pair in the List: {Match[Object,"Hello World"],Match["Second String", 5]}, in a streamed manner (no overlapping matches). Ofcourse, my implementation will have grouping, lookahead/lookbehinds and is hierarchical (i.e. matching n elements from Lists in Lists), etc. The above merely illustrates the concept. Is there a name for this principle, and is there literature available on it?

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• Exporting dataset to Excel file with multiple sheets in ASP.NET

  - by engg

  In C# ASP.NET 3.5 web application, I need to export multiple datatables (or a dataset) to an Excel 2007 file with multiple sheets, and then provide the user with 'Open/Save' dialog box, WITHOUT saving the Excel file on the web server. I have used Excel Interop before. I have been reading that it's not efficient and is not the best approach to achieve this and there are more ways to do it, 2 of them being: 1) Converting data in datatables to an XML string that Excel understands 2) Using OPEN XML SDK 2.0. It looks like OPEN XML SDK 2.0 is better, please let me know. Are there any other ways to do it? I don't want to use any third-party tools. If I use OPEN XML SDK, it creates an excel file, right? I don't want to save it on the (Windows 2003) server hard drive (I don't want to use Server.MapPath, these Excel files are dynamically created, and they are not required on the server, once client gets them). I directly want to prompt the user to open/save it. I know how to do it when the 'XML string' approach is used. Please help. Thank you.

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• Caching page by parts; how to pass variables calculated in cached parts into never-cached parts?

  - by Kirzilla

  Hello, Let's imagine that I have a code like this... if (!$data = $cache->load("part1_cache_id")) { $item_id = $model->getItemId(); ob_start(); echo 'Here is the cached item id: '.$item_id; $data = ob_get_contents(); ob_end_clean(); $cache->save($data, "part1_cache_id"); } echo $data; echo never_cache_function($item_id); if (!$data_2 = $cache->load("part2_cache_id")) { ob_start(); echo 'Here is the another cached part of the page...'; $data_2 = ob_get_contents(); ob_end_clean(); $cache->save("part2_cache_id"); } echo $data_2; As far as you can see I need to pass $item_id variable into never_cache_function, but if fist part is cached (part1_cache_id) then I have no way to get $item_id value. I see the only solution - serialize all data from fist part (including $item_id value); then cache serialized string and unserialize it everytime when script is executed... Something like this... if (!$data = $cache->load("part1_cache_id")) { $item_id = $model->getItemId(); $data['item_id'] = $item_id; ob_start(); echo 'Here is the cached item id: '.$item_id; $data['html'] = ob_get_contents(); ob_end_clean(); $cache->save( serialize($data), "part1_cache_id" ); } $data = unserialize($data); echo $data['html'] echo never_cache_function($data['item_id']); Is there any other ways for doing such trick? I'm looking for the most high performance solution. Thank you UPDATED And another question is - how to implement such caching into controller without separating page into two templates? Is it possible? PS: Please, do not suggest Smarty, I'm really interested in implementing custom caching.

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• How much should the AppDelegate do?

  - by Rudiger

  I'm designing quite a large App and on startup it will create sessions with a few different servers. As they are creating a session which is used across all parts of the app its something I thought would be best in App Delegate. But the problem is I need the session progress to be represented on the screen. I plan to have a UIToolBar at the bottom of the main menu which I don't want to cover with the progress bar but cover the UIView above it.So the way I see it I could do it a few different ways. 1) Have the App Delegate establish the sessions and report the progress to the main menu class so it can represent it in the progress bar (will I have any issues doing this if the sessions are created in a separate thread?), 2) have the App delegate display the main menu (UIView with a bunch of buttons and UIToolBar) and have it track and display the progress (I have never displayed anything in the App Delegate but assume you can do this but its not recommended) or 3) have the App Delegate just push the main menu and have the mainMenu class create the sessions and display the progress bar. 4) I think the other way to do it is to create the sessions in a delegate class and have the delegate set to mainMenu rather than self (AppDelegate), although I've never used anything other then self so not sure if this will work or if I will be able to close the thread (through calling super maybe?) as its running in the AppDelegate rather than the delegate of the class. As I've kinda said before the sessions are being created in a class in a separate thread so it wont lock the UI and I think the best way is the first but am I going to have issues having it running in a separate thread, reporting back to the app delegate and then sending that message to the mainMenu view? I hope that all makes sense, let me know if you need any further clarification. Any information is appreciated Cheers,

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• desing pattern for related inputs

  - by curiousMo

  My question is a design question : let's say i have a data entry web page with 4 drop down lists, each depending on the previous one, and a bunch of text boxes. country (ddl), state (ddl), city (ddl), boro (ddl), address (txtBox), zipcode(txtbox). and an object that represents a datarow with a value for each. naturally the country, state, city and boro values will be values of primary keys of some lookup tables. when the user chooses to edits that record, i would load it from database and load it into the page. the issue that I have is how to streamline loading the ddls. i have some code that would grab the object, look thru its values and move them to their corresponding input controls in one shot. but in this case i will have to load possible values of country, then assign values, then load values of state, then assign value ans so on. I guess i am looking for an elegant solution. i am using asp.net, but i think it is irrelevant to the question. i am looking more into a design pattern. thanks

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• Issue in parsing the GridViewRows in a Telerik RadGridView

  - by cricketmovies

  Hi, I would like to do something similar what we do in ASP.NET where we parse through all the rows in a GridView and assign a particular value to a particular cell in a row which has a matching TaskId as the current Id. This has to happen in a Tick function of a Dispatcher Timer object. Since I have a Start Timer button Column for every row in a GridView. Upon a particular row's Start Timer Button click, I have to start its timer and display in a cell in that row. Similarly there can be multiple timers running in parallel. For this I need to be able to check the task Id of the particular task and keep updating the cell values with the updated time in all of the tasks that have a Timer Started. TimeSpan TimeRemaining = somevalue; string CurrentTaskId = "100"; foreach(GridViewRow row in RadGridView1.Rows) // Here I tried RadGridView1.ChildrenOfType() as well but it has null { if( (row.DataContext as Task).TaskId == CurrentTaskId ) row.Cells[2].Content = a.TaskTimeRemaining.ToString(); } Can someone please let me know how do I get this functionality using the Telerik RadGridView? Cheers, Syed.

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• Issue Implementing Colorbox Correctly in IE (all versions)

  - by Andrew

  I've been pulling my hair out (and going way over allotted hours) to try and figure out why Colorbox isn't working properly on the following page: http://www.fiberforge.com I've set up a Colorbox test link on the very bottom right that says "Web Design By All Web Cafe", which should open up a small logo image. In Firefox, Safari, etc the modal behaves as it should, opening center center above all of the existing on-page content. In IE, not only is the modal not centered, but it appears as though it's not obeying absolute positioning and pushing all of the existing on-page content down below. Add to that the fact that it's not opening to the correct size and creating scrollbars next to the modal image, and we have ourselves one ugly modal. The scrollbars I can live with (by just resizing the min-height of the modal), but I can't figure out why it won't center. Let me say that I did not code this site initially and it was completed quite a few years ago, so there are quite probably numerous CSS hacks to get things to display properly, any number of which may be causing this problem. By contrast, Thickbox is also set up on this site (if you click on the "Play Video" callout in the dark blue area) and behaves correctly, though suffers from some weird sizing/padding issues, hence the desire to replace it with something a bit more modern and extensible. I can verify that there is no conflict having both of these modal scripts/CSS files concurrently as the problem still occurs with Colorbox even when Thickbox is removed entirely. Any thoughts or suggestions would be greatly appreciated.

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• Retrieve a list of the most popular GET param variations for a given URL?

  - by jamtoday

  I'm working on building intelligence around link propagation, and because I need to deal with many short URL services where a reverse-lookup from an exact URL address is required, I need to be able to resolve multiple approximate versions of the same URL. An example would be a URL like http://www.example.com?ref=affil&hl=en&ct=0 Of course, changing GET params in certain circumstances can refer to a completely different page, especially if the GET params in question refer to a profile or content ID. But a quick parse of the page would quickly determine how similar the pages were to each other. Using a bit of machine learning, it could quickly become clear which GET params don't effect the content of the pages returned for a given site. I'm assuming a service to send a URL and get a list of very similar URLs could only be offered by the likes of Google or Yahoo (or Twitter), but they don't seem to offer this feature, and I haven't found any other services that do. If you know of any services that do cluster together groups of almost identical URLs in the aforementioned way, please let me know. My bounty is a hug.

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• How to create a CGBitmapContext which works for Retina display and not wasting space for regular display?

  - by ????

  Is it true that if it is in UIKit, including drawRect, the HD aspect of Retina display is automatically handled? So does that mean in drawRect, the current graphics context for a 1024 x 768 view is actually a 2048 x 1536 pixel Bitmap context? (is there a way to print this size out to verify it). We actually enjoy the luxury of 1 point = 4 pixels automatically handled for us. However, if we use CGBitmapContextCreate, then those will really be pixels, not points? (at least if we provide a data buffer for that bitmap, the size is not for the higher resolution, but for the standard resolution, and even if we pass NULL as the buffer so that CGBitmapContextCreate handles the buffer for us, the size probably is the same as if we pass in a data buffer, and it is just standard resolution, not Retina's resolution). We can always create 2048 x 1536 for iPad 1 and iPad 2 as well as the New iPad, but it will waste memory and processor and GPU power, as it is only needed for the New iPad. So do we have to use a if () { } else { } to create such a bitmap context and how do we actually do so? And all our code CGContextMoveToPoint has to be adjusted for Retina display to use x * 2 and y * 2 vs non-retina display of just using x, y as well? That can be quite messy for the code. (or maybe we can define a local variable scaleFactor and set it to 1 for standard resolution and 2 if it is retina, so our x and y will always be x * scaleFactor, y * scaleFactor instead of just x and y.) It seems that UIGraphicsBeginImageContextWithOptions can create one for Retina automatically if the scale of 0.0 is passed in, but I don't think it can be used if I need to create the context and keep it (and using ivar or property of UIViewController to hold it). If I don't release it using UIGraphicsEndImageContext, then it stays in the graphics context stack, so it seems like I have to use CGBitmapContextCreate instead. (or do we just let it stay at the bottom of the stack and not worry about it?)

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• Uploading XML with NSInputStream Iphone....

  - by Aks

  Hi, I have to upload XML string to server & the Web service expect it in body stream part of the http request. So i am allocating the NSInputstream instance with xml data & then setting it the part of the http string but it uploading the stream body NULL & in my code if check the Stream status, it gives error & size null, Could you let me know how to get it done , also pasting the code. Code: NSInputStream* stream = [[[NSInputStream alloc]initWithData:streamData]retain]; request=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:nss_url]]; NSString *msgLength = [NSString stringWithFormat:@"%d", [message length]]; [request addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"]; [request addValue: @"http://www.XYZ.COM/ACL" forHTTPHeaderField:@"SOAPAction"]; [request addValue: msgLength forHTTPHeaderField:@"Content-Length"]; [request setHTTPBodyStream:[NSInputStream inputStreamWithData:streamData]]; [request setHTTPMethod:@"POST"]; NSLog(@"The input stream is %@ & error is %@",[stream streamStatus],[stream streamError]); Its gives: The input stream is (null) & error is Error Domain=NSUnknownErrorDomain Code=0 "Operation could not be completed. (NSUnknownErrorDomain error 0.)" Any inputs what I am missing ..........

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• find and replace values in a flat-file using PHP

  - by peirix

  I'd think there was a question on this already, but I can't find one. Maybe the solution is too easy... Anyway, I have a flat-file and want to let the user change the values based on a name. I've already sorted out creating new name+value-pairs using the fopen('a') mode, using jQuery to send the AJAX call with newValue and newName. But say the content looks like this: host|http:www.stackoverflow.com folder|/questions/ folder2|/users/ And now I want to change the folder value. So I'll send in folder as oldName and /tags/ as newValue. What's the best way to overwrite the value? The order in the list doesn't matter, and the name will always be on the left, followed by a |(pipe), the value and then a new-line. My first thought was to read the list, store it in an array, search all the [0]'s for oldName, then change the [1] that belongs to it, and then write it back to a file. But I feel there is a better way around this? Any ideas? Maybe regex?

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• Right way of making muti-site and multi-lingual website on codeigniter

  - by DR.GEWA

  Hi there. Beforehand let me thank you all !! Really guys you help a lot. When I will finish my web site and will have much time on watching how userbase is growing I will come here again and again to answer to another people questions(if I can ) So here is the problem. I made a web-site on CodeIgniter. A social network engine. Something like phpfox, classmates_com or facebook. It's right now somehow not multilingual, So the UI strings are in the view files, and next step will be move them to the language files. I want the user to have ability to change the language. So I assume that in database user will have row "lang_local" which would be by default set to en, and then to any other language he will change . So what is eating my nervs and enery is following. I will make on this engine several demographic social networks,and I would like to manage theese web-sites in centralized manner with one backend . So whenever I would like to make a new web-network, I just add the domain settings install the script in new folder and add it in database sites I see it like this on every table in database like users,comments,messages,categories ,etc I will have a row site_id , and on each query add/update/delete I add a WHERE SITE_ID=XXX and in table sites(site_id,site_name,domain_name) will have all domains , so that in backend I can filter data by website. Is this a good way? What if i will need then to be multiserver, what about load balancing? Who can tell me what would be a right,PROFESSIONAL way? My maximum user limit for a database is something like for start 10.000 in one-two year 100.000users

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• How to implement "business rules" in Rails?

  - by Zabba

  What is the way to implement "business rules" in Rails? Let us say I have a car and want to sell it: car = Cars.find(24) car.sell car.sell method will check a few things: does current_user own the car? check: car.user_id == current_user.id is the car listed for sale in the sales catalog? check: car.catalogs.ids.include? car.id if all o.k. then car is marked as sold. I was thinking of creating a class called Rules: class Rules def initialize(user,car) @user = user @car = car end def can_sell_car? @car.user_id == @user.id && @car.catalogs.ids.include? @car.id end end And using it like this: def Car def sell if Rules.new(current_user,self).can_sell_car ..sell the car... else @error_message = "Cannot sell this car" nil end end end As for getting the current_user, I was thinking of storing it in a global variable? I think that whenever a controller action is called, it's always a "fresh" call right? If so then storing the current user as a global variable should not introduce any risks..(like some other user being able to access another user's details) Any insights are appreciated! UPDATE So, the global variable route is out! Thanks to PeterWong for pointing out that global variables persist! I've now thinking of using this way: class Rules def self.can_sell_car?(current_user, car) ......checks.... end end And then calling Rules.can_sell_car?(current_user,@car) from the controller action. Any thoughts on this new way?

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• Use a vector to index a matrix without linear index

  - by David_G

  G'day, I'm trying to find a way to use a vector of [x,y] points to index from a large matrix in MATLAB. Usually, I would convert the subscript points to the linear index of the matrix.(for eg. Use a vector as an index to a matrix in MATLab) However, the matrix is 4-dimensional, and I want to take all of the elements of the 3rd and 4th dimensions that have the same 1st and 2nd dimension. Let me hopefully demonstrate with an example: Matrix = nan(4,4,2,2); % where the dimensions are (x,y,depth,time) Matrix(1,2,:,:) = 999; % note that this value could change in depth (3rd dim) and time (4th time) Matrix(3,4,:,:) = 888; % note that this value could change in depth (3rd dim) and time (4th time) Matrix(4,4,:,:) = 124; Now, I want to be able to index with the subscripts (1,2) and (3,4), etc and return not only the 999 and 888 which exist in Matrix(:,:,1,1) but the contents which exist at Matrix(:,:,1,2),Matrix(:,:,2,1) and Matrix(:,:,2,2), and so on (IRL, the dimensions of Matrix might be more like size(Matrix) = (300 250 30 200) I don't want to use linear indices because I would like the results to be in a similar vector fashion. For example, I would like a result which is something like: ans(time=1) 999 888 124 999 888 124 ans(time=2) etc etc etc etc etc etc I'd also like to add that due to the size of the matrix I'm dealing with, speed is an issue here - thus why I'd like to use subscript indices to index to the data. I should also mention that (unlike this question: Accessing values using subscripts without using sub2ind) since I want all the information stored in the extra dimensions, 3 and 4, of the i and jth indices, I don't think that a slightly faster version of sub2ind still would not cut it..

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• Plotting andrews curves of subsets of a data frame on the same plot

  - by user2976477

  I have a data frame of 12 columns and I want to plot andrews curves in R of this data, basing the color of the curves on the 12th columns. Below are a few samples from the data (sorry the columns are not aligned with the numbers) Teacher_explaining Teacher_enthusiastic Teacher_material_interesting Material_stimulating Material_useful Clear_marking Marking_fair Feedback_prompt Feedback_clarifies Detailed_comments Notes Year 80 80 80 80 85 85 80 80 80 80 70 3 70 60 30 40 70 60 30 40 70 0 30 3 100 90 90 80 80 100 100 90 100 100 100 MSc 85 85 85 90 90 70 90 50 70 80 100 MSc 90 50 90 90 90 70 100 50 80 100 100 4 100 80 80 75 90 80 80 50 80 80 90 3 From this data I tried to plot andrews curves using the code below: install.packages("andrews") library(andrews) col <- as.numeric(factor(course[,12])) andrews(course[,1:12], clr = 12) However, the 12th column has three groups (3 types of responses) and I want to group two of them and then plot the andrews curve of the data, without editing my data frame in Excel. x <- subset(course, Year == "MSc" & "4") y <- subset(course, Year == "3") I tried the above code, but my argument for x don't work. "MSc", "3" and "4" are the groups in the 12th column, and I want to group MSc and 4 so that their Andrews curves have the same color. If you have any idea how to do this, please let me know.

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• Using Sub-Types And Return Types in Scala to Process a Generic Object Into a Specific One

  - by pr1001

  I think this is about covariance but I'm weak on the topic... I have a generic Event class used for things like database persistance, let's say like this: class Event( subject: Long, verb: String, directobject: Option[Long], indirectobject: Option[Long], timestamp: Long) { def getSubject = subject def getVerb = verb def getDirectObject = directobject def getIndirectObject = indirectobject def getTimestamp = timestamp } However, I have lots of different event verbs and I want to use pattern matching and such with these different event types, so I will create some corresponding case classes: trait EventCC case class Login(user: Long, timestamp: Long) extends EventCC case class Follow( follower: Long, followee: Long, timestamp: Long ) extends EventCC Now, the question is, how can I easily convert generic Events to the specific case classes. This is my first stab at it: def event2CC[T <: EventCC](event: Event): T = event.getVerb match { case "login" => Login(event.getSubject, event.getTimestamp) case "follow" => Follow( event.getSubject, event.getDirectObject.getOrElse(0), event.getTimestamp ) // ... } Unfortunately, this is wrong. <console>:11: error: type mismatch; found : Login required: T case "login" => Login(event.getSubject, event.getTimestamp) ^ <console>:12: error: type mismatch; found : Follow required: T case "follow" => Follow(event.getSubject, event.getDirectObject.getOrElse(0), event.getTimestamp) Could someone with greater type-fu than me explain if, 1) if what I want to do is possible (or reasonable, for that matter), and 2) if so, how to fix event2CC. Thanks!

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• Python many-to-one mapping (creating equivalence classes)

  - by Adam Matan

  Hi, I have a project of converting one database to another. One of the original database columns defines the row's category. This coulmn should be mapepd to a new category in the new databse. For example, let's assume the original categories are:parrot, spam, cheese_shop, Cleese, Gilliam, Palin Now that's a little verbose for me, And I want to have these rows categorized as sketch, actor - That is, define all the sketches and all the actors as two equivalence classes. >>> monty={'parrot':'sketch', 'spam':'sketch', 'cheese_shop':'sketch', 'Cleese':'actor', 'Gilliam':'actor', 'Palin':'actor'} >>> monty {'Gilliam': 'actor', 'Cleese': 'actor', 'parrot': 'sketch', 'spam': 'sketch', 'Palin': 'actor', 'cheese_shop': 'sketch'} That's quite awkward- I would prefer having something like: monty={ ('parrot','spam','cheese_shop'): 'sketch', ('Cleese', 'Gilliam', 'Palin') : 'actors'} But this, of course, sets the entire tuple as a key: >>> monty['parrot'] Traceback (most recent call last): File "<pyshell#29>", line 1, in <module> monty['parrot'] KeyError: 'parrot' Any ideas how to create an elegant many-to-one dictionary in Python? Thanks, Adam

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• Scala programming language for beginners, is it a legend?

  - by ali

  Hi every one, I am Ali from Saudi Arabia. undoubtedly, Scala is one of the best programming language for any programmer to learn, but there is "good" problems that is faced especially by beginners, and what seems frustrating that these problems won't solve soon, so as a beginner and on behalf of beginners let me raise these "objective" questions: 1- why scala has no effective and stable development platform, in fact, it suffers many problems with Eclipse, Netbeat, and Intellij. 2- although I have looked for a clear,easy, and understandable explanation of how to get started with Scala, but fortunately, there was no article or guide that deserves to spend the time I have spent to read it. nobody could tell you clear steps that fit you as a beginner who wants to start his"HELLO WORLD" with Scala, while all other languages have its "HELLO WORLD" guides and books. thank you for your time, be sure that you read notes below. 1- I have no experience in programming language before. 2- don't tell me "not to begin with scala", simply, because I will do. 3- OS is windows vista home premium. 4- I hate excuses, such as Scala is new language......etc

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