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• Properly design a code editor application

  - by Hemaulo

  I'm working on personal project which is basically a code editor. Imagine standard File menu with menu items New, Open, Save, Save As, Save All, Close, Close All. I'm stuck with proper design. Currently I have: A Document class which represents a document - code editing control, respective tab in tab bar and various properties such as Caption, Filename, IsModified etc. A Documents class which represents all open documents. Contains methods like New, Open(FileName), ... The problem is that I can't figure out which class / menu command is responsible for which tasks. For example, with File-New menu command is simple - call Documents.New and that's it. But what for File-Open? The Documents.Open method expects filename as a parameter. So before calling this method I need to open an file selection dialog, let user select files and for each file call Documents.Open(FileName). Where is best place for this supporting code, in menu command, rewrite Documents.Open and put it there? The same with Save actions. Which is responsible for saving? Is it Documents class which uses Document.Editor.SaveToFile(FileName) or better create Save method in Document class? Somewhere in the middle also need to ask user if he wants to save current document... I'm stuck. Any ideas? Edited: The programming language is Delphi.

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• how can I save/keep-in-sync an in-memory graph of objects with the database?

  - by Greg

  Question - What is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Background: That is say I have the classes Node and Relationship, and the application is building up a graph of related objects using these classes. There might be 1000 nodes with various relationships between them. The application needs to query the structure hence an in-memory approach is good for performance no doubt (e.g. traverse the graph from Node X to find the root parents) The graph does need to be persisted however into a database with tables NODES and RELATIONSHIPS. Therefore what is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Ideal requirements would include: build up changes in-memory and then 'save' afterwards (mandatory) when saving, apply updates to database in correct order to avoid hitting any database constraints (mandatory) keep persistence mechanism separate from model, for ease in changing persistence layer if needed, e.g. don't just wrap an ADO.net DataRow in the Node and Relationship classes (desirable) mechanism for doing optimistic locking (desirable) Or is the overhead of all this for a smallish application just not worth it and I should just hit the database each time for everything? (assuming the response times were acceptable) [would still like to avoid if not too much extra overhead to remain somewhat scalable re performance]

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• Merge Multple Worksheets From Multple Workbooks

  - by Droter

  Hi, I have found multiple posts on merging data but I am still running into some problems. I have multiple files with multiple sheets. Example 2007-01.xls...2007-12.xls in each of these files are daily data on sheets labeled 01, 02, 03 ..... There are other sheets in the file so I can't just loop through all worksheets. I need to combine the daily data into monthly data, then all of the monthly data points into yearly. On the monthly data I need it to be added to the bottom of the page. I have added the file open changes for Excel 2007 Here is what I have so far: Sub RunCodeOnAllXLSFiles() Dim lCount As Long Dim wbResults As Workbook Dim wbMaster As Workbook Application. ScreenUpdating = False Application.DisplayAlerts = False Application.EnableEvents = False On Error Resume Next Set wbMaster = ThisWorkbook Dim oWbk As Workbook Dim sFil As String Dim sPath As String sPath = "C:\Users\test\" 'location of files ChDir sPath sFil = Dir("*.xls") 'change or add formats Do While sFil <> "" 'will start LOOP until all files in folder sPath have been looped through Set oWbk = Workbooks.Open(sPath & "\" & sFil) 'opens the file Set oWbk = Workbooks.Open(sPath & "\" & sFil) Sheets("01").Select ' HARD CODED FIRST DAY Range("B6:F101").Select 'AREA I NEED TO COPY Range("B6:F101").Copy wbMaster.Activate Workbooks("wbMaster").ActiveSheet.Range("B65536").End(xlUp)(2).PasteSpecial Paste:=xlValues Application.CutCopyMode = False oWbk.Close True 'close the workbook, saving changes sFil = Dir Loop ' End of LOOP On Error Goto 0 Application.ScreenUpdating = True Application.DisplayAlerts = True Application.EnableEvents = True End Sub Right now it can find the files and open them up and get to the right worksheet but when it tries to copy the data nothing is copied over. Thanks for your help, Matt

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• Using Javascript to generate and save a file

  - by Toji

  I've been fiddling with WebGL lately, and have gotten a Collada reader working. Problem is it's pretty slow (Collada is a very verbose format), so I'm going to start converting files to a easier to use format (probably JSON). Thing is, I already have the code to parse the file in Javascript, so I may as well use it as my exporter too! The problem is saving. Now, I know that I can parse the file, send the result to the server, and have the browser request the file back from the server as a download. But in reality the server has nothing to do with this particular process, so why get it involved? I already have the contents of the desired file in memory. Is there any way that I could present the user with a download using pure javascript? (I doubt it, but might as well ask...) And to be clear: I am not trying to access the filesystem without the users knowledge! The user will provide a file (probably via drag and drop), the script will transform the file in memory, and the user will be prompted to download the result. All of which should be "safe" activities as far as the browser is concerned.

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• When is a good time to start thinking about scaling?

  - by Slokun

  I've been designing a site over the past couple days, and been doing some research into different aspects of scaling a site horizontally. If things go as planned, in a few months (years?) I know I'd need to worry about scaling the site up and out, since the resources it would end up consuming would be huge. So, this got me to thinking, when is the best time to start thinking about, and designing for, scalability? If you start too early on, you could easily over complicate your design, and make it impossible to actually build. You could also get too caught up in the details, the architecture, whatever, and wind up getting nothing done. Also, if you do get it working, but the site never takes off, you may have wasted a good chunk of extra effort. On the other hand, you could be saving yourself a ton of effort down the road. Designing it from the ground up to be big would make it much easier later on to let it grow big, with very little rewriting going on. I know for what I'm working on, I've decided to make at least a few choices now on the side of scaling, but I'm not going to do a complete change of thinking to get it to scale completely. Notably, I've redesigned my database from a conventional relational design to one similar to what was suggested on the Reddit site linked below, and I'm going to give memcache a try. So, the basic question, when is a good time to start thinking or worrying about scaling, and what are some good designs, tips, etc. for when doing so? A couple of things I've been reading, for those who are interested: http://www.codinghorror.com/blog/2009/06/scaling-up-vs-scaling-out-hidden-costs.html http://highscalability.com/blog/2010/5/17/7-lessons-learned-while-building-reddit-to-270-million-page.html http://developer.yahoo.com/performance/rules.html

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• Executing logic before save or validation with EF Code-First Models

  - by Ryan Norbauer

  I'm still getting accustomed to EF Code First, having spent years working with the Ruby ORM, ActiveRecord. ActiveRecord used to have all sorts of callbacks like before_validation and before_save, where it was possible to modify the object before it would be sent off to the data layer. I am wondering if there is an equivalent technique in EF Code First object modeling. I know how to set object members at the time of instantiation, of course, (to set default values and so forth) but sometimes you need to intervene at different moments in the object lifecycle. To use a slightly contrived example, say I have a join table linking Authors and Plays, represented with a corresponding Authoring object: public class Authoring { public int ID { get; set; } [Required] public int Position { get; set; } [Required] public virtual Play Play { get; set; } [Required] public virtual Author Author { get; set; } } where Position represents a zero-indexed ordering of the Authors associated to a given Play. (You might have a single "South Pacific" Play with two authors: a "Rodgers" author with a Position 0 and a "Hammerstein" author with a Position 1.) Let's say I wanted to create a method that, before saving away an Authoring record, it checked to see if there were any existing authors for the Play to which it was associated. If no, it set the Position to 0. If yes, it would find set the Position of the highest value associated with that Play and increment by one. Where would I implement such logic within an EF code first model layer? And, in other cases, what if I wanted to massage data in code before it is checked for validation errors? Basically, I'm looking for an equivalent to the Rails lifecycle hooks mentioned above, or some way to fake it at least. :)

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• ArrayList<String> NullPointerException

  - by Carlucho

  Am trying to solve a labyrinth by DFS, using adj List to represent the vertices and edges of the graph. In total there are 12 nodes (3 rows[A,B,C] * 4 cols[0,..,3]). My program starts by saving all the vertex labels (A0,..C3), so far so good, then checks the adjacent nodes, also no problems, if movement is possible, it proceeds to create the edge, here its where al goes wrong. adjList[i].add(vList[j].label); I used the debugger and found that vList[j].label is not null it contains a correct string (ie. "B1"). The only variables which show null are in adjList[i], which leads me to believe i have implemented it wrongly. this is how i did it. public class GraphList { private ArrayList<String>[] adjList; ... public GraphList(int vertexcount) { adjList = (ArrayList<String>[]) new ArrayList[vertexCount]; ... } ... public void addEdge(int i, int j) { adjList[i].add(vList[j].label); //NULLPOINTEREXCEPTION HERE } ... } I will really appreaciate if anyone can point me on the right track regrading to what its going wrong... Thanks!

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• Please critique this method

  - by Jakob

  Hi I've been looking around the net for some tab button close functionality, but all those solutions had some complicated eventhandler, and i wanted to try and keep it simple, but I might have broken good code ethics doing so, so please review this method and tell me what is wrong. public void AddCloseItem(string header, object content){ //Create tabitem with header and content StackPanel headerPanel = new StackPanel() { Orientation = Orientation.Horizontal, Height = 14}; headerPanel.Children.Add(new TextBlock() { Text = header }); Button closeBtn = new Button() { Content = new Image() { Source = new BitmapImage(new Uri("images/cross.png", UriKind.Relative)) }, Margin = new Thickness() { Left = 10 } }; headerPanel.Children.Add(closeBtn); TabItem newTabItem = new TabItem() { Header = headerPanel, Content = content }; //Add close button functionality closeBtn.Tag = newTabItem; closeBtn.Click += new RoutedEventHandler(closeBtn_Click); //Add item to list this.Add(newTabItem); } void closeBtn_Click(object sender, RoutedEventArgs e) { this.Remove((TabItem)((Button)sender).Tag); } So what I'm doing is storing the tabitem in the btn.Tag property, and then when the button is clicked i just remove the tabitem from my observablecollection, and the UI is updated appropriately. Am I using too much memory saving the tabitem to the Tag property?

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• DataSets to POCOs - an inquiry regarding DAL architecture

  - by alexsome

  Hello all, I have to develop a fairly large ASP.NET MVC project very quickly and I would like to get some opinions on my DAL design to make sure nothing will come back to bite me since the BL is likely to get pretty complex. A bit of background: I am working with an Oracle backend so the built-in LINQ to SQL is out; I also need to use production-level libraries so the Oracle EF provider project is out; finally, I am unable to use any GPL or LGPL code (Apache, MS-PL, BSD are okay) so NHibernate/Castle Project are out. I would prefer - if at all possible - to avoid dishing out money but I am more concerned about implementing the right solution. To summarize, there are my requirements: Oracle backend Rapid development (L)GPL-free Free I'm reasonably happy with DataSets but I would benefit from using POCOs as an intermediary between DataSets and views. Who knows, maybe at some point another DAL solution will show up and I will get the time to switch it out (yeah, right). So, while I could use LINQ to convert my DataSets to IQueryable, I would like to have a generic solution so I don't have to write a custom query for each class. I'm tinkering with reflection right now, but in the meantime I have two questions: Are there any problems I overlooked with this solution? Are there any other approaches you would recommend to convert DataSets to POCOs? Thanks in advance.

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• Emailing an excel sheet with SSL in Python

  - by jakecar

  Hi...this is my first post so let me know if there are any common courtesies I should know about. I just started programming 8 months ago, so I am fairly new. I have been doing some projects to get better. A project I'm working on now creates an Excel sheet from inputted data. It's in Python, which I just started learning a couple of weeks ago. I'm attempting to embed part of this Excel sheet into an email, sent from my school address. I have spent hours looking this up, and to no avail. There are two problems I am asking for help with: 1) I have figured out how to send an email from my GMail account, but not from my school address. My school email uses SSL port 465, which I have tried to use, but to no avail. Unfortunately, I have been having a problem setting up outgoing email for this account on my iPhone as well. It may be related? Does anyone know of common issues relating to outgoing email with SSL and Python? 2) Excel has an option of saving a sheet as a HTML. When doing so, I copy and pasted the HTML source and emailed it as an attachment. Unfortunately, the colored text did not transfer over. Does anyone know of a better way of using Python to send an excel sheet embedded in an email? Thanks for your help!

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• Should a setter return immediately if assigned the same value?

  - by Andrei Rinea

  In classes that implement INotifyPropertyChanged I often see this pattern : public string FirstName { get { return _customer.FirstName; } set { if (value == _customer.FirstName) return; _customer.FirstName = value; base.OnPropertyChanged("FirstName"); } } Precisely the lines if (value == _customer.FirstName) return; are bothering me. I've often did this but I am not that sure it's needed nor good. After all if a caller assigns the very same value I don't want to reassign the field and, especially, notify my subscribers that the property has changed when, semantically it didn't. Except saving some CPU/RAM/etc by freeing the UI from updating something that will probably look the same on the screen/whatever_medium what do we obtain? Could some people force a refresh by reassigning the same value on a property (NOT THAT THIS WOULD BE A GOOD PRACTICE HOWEVER)? 1. Should we do it or shouldn't we? 2. Why?

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• File based caching under PHP

  - by azatoth

  I've been using http://code.google.com/p/phpbrowscap/ for a project, and it usually works nice. But a few times it's cache, which is plain php-files (see http://code.google.com/p/phpbrowscap/source/browse/trunk/browscap/Browscap.php#372 et. al.), has been "zeroed", i.e. the whole cache file has become large blob of NULLs. Instead of trying to find out why the files become NULL, I though perhaps it might be better to change the caching strategy to something more resilient. So I do wonder if you has any good ideas what would be a good solution; I've been looking at http://www.jongales.com/blog/2009/02/18/simple-file-based-php-cache-class/ and http://www.phpclasses.org/package/313-PHP-Cache-arbitrary-data-in-files-.html and I also though of just saving an serialized array to the file instead of pure php as it's been doing now; But I'm uncertain what approach I should target here. I'm grateful for any insight into this area of technology, as I know it's complex from a performance point of view.

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• Weird camera Intent behavior

  - by David Erosa

  Hi all. I'm invoking the MediaStore.ACTION_IMAGE_CAPTURE intent with the MediaStore.EXTRA_OUTPUT extra so that it does save the image to that file. On the onActivityResult I can check that the image is being saved in the intended file, which is correct. The weird thing is that anyhow, the image is also saved in a file named something like "/sdcard/Pictures/Camera/1298041488657.jpg" (epoch time in which the image was taken). I've checked the Camera app source (froyo-release branch) and I'm almost sure that the code path is correct and wouldn't have to save the image, but I'm a noob and I'm not completly sure. AFAIK, the image saving process starts with this callback (comments are mine): private final class JpegPictureCallback implements PictureCallback { ... public void onPictureTaken(...){ ... // This is where the image is passed back to the invoking activity. mImageCapture.storeImage(jpegData, camera, mLocation); ... public void storeImage(final byte[] data, android.hardware.Camera camera, Location loc) { if (!mIsImageCaptureIntent) { // Am i an intent? int degree = storeImage(data, loc); // THIS SHOULD NOT BE CALLED WITHIN THE CAPTURE INTENT!! ....... // An finally: private int storeImage(byte[] data, Location loc) { try { long dateTaken = System.currentTimeMillis(); String title = createName(dateTaken); String filename = title + ".jpg"; // Eureka, timestamp filename! ... So, I'm receiving the correct data, but it's also being saved in the "storeImage(data, loc);" method call, which should not be called... It'd not be a problem if I could get the newly created filename from the intent result data, but I can't. When I found this out, I found about 20 image files from my tests that I didn't know were on my sdcard :) I'm getting this behavior both with my Nexus One with Froyo and my Huawei U8110 with Eclair. Could please anyone enlight me? Thanks a lot.

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• How to perform Rails model validation checks within model but outside of filters using ledermann-rails-settings and extensions

  - by user1277160

  Background I'm using ledermann-rails-settings (https://github.com/ledermann/rails-settings) on a Rails 2/3 project to extend virtually the model with certain attributes that don't necessarily need to be placed into the DB in a wide table and it's working out swimmingly for our needs. An additional reason I chose this Gem is because of the post How to create a form for the rails-settings plugin which ties ledermann-rails-settings more closely to the model for the purpose of clean form_for usage for administrator GUI support. It's a perfect solution for addressing form_for support although... Something that I'm running into now though is properly validating the dynamic getters/setters before being passed to the ledermann-rails-settings module. At the moment they are saved immediately, regardless if the model validation has actually fired - I can see through script/console that validation errors are being raised. Example For instance I would like to validate that the attribute :foo is within the range of 0..100 for decimal usage (or even a regex). I've found that with the previous post that I can use standard Rails validators (surprise, surprise) but I want to halt on actually saving any values until those are addressed - ensure that the user of the GUI has given 61.43 as a numerical value. The following code has been borrowed from the quoted post. class User < ActiveRecord::Base has_settings validates_inclusion_of :foo, :in => 0..100 def self.settings_attr_accessor(*args) >>SOME SORT OF UNLESS MODEL.VALID? CHECK HERE args.each do |method_name| eval " def #{method_name} self.settings.send(:#{method_name}) end def #{method_name}=(value) self.settings.send(:#{method_name}=, value) end " end >>END UNLESS end settings_attr_accessor :foo end Anyone have any thoughts here on pulling the state of the model at this point outside of having to put this into a before filter? The goal here is to be able to use the standard validations and avoid rolling custom validation checks for each new settings_attr_accessor that is added. Thanks!

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• Core Data: Overkill for simple, static UITableView-based iPhone App?

  - by David Foster

  Hello! I have a rather simple iPhone app consisting of numerous views containing a single, grouped table view. These views are held together in navigation controllers which are grouped in a tab bar. Simple stuff. My table views do little more than list text (like "Dog", "Cat" and "Weasel") and this data is being served from a collection of plists. It's perhaps worth mentioning too that these tables are 'static' in the sense that their data is pre-determined and will only ever be amended—and if so, very rarely indeed—by the developer (in this case, moi). This rudimentary approach has reached its limits though, and I think I'm going to need something a bit more relational. I have worked a tad with Core Data in the past, but only with apps whose data is determined by user input. I have four closely related questions: Is Core Data overkill for an app consisting mainly of a selection of simple table views? Do you recommend using Core Data to manage data which is predetermine and extremely unlikely to ever change? Can one lock Core Data down so that its data can't change, thereby relinquishing my responsibility as the developer to handle the editing and saving of the managed object context? How do I go about giving Core Data my predetermined data, and in a format I know that it can work with? Thanks a bunch guys.

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• Parameter cannot be null error after success save

  - by tigermain

  I am getting the following nhibernate error when saving an entity (via: NHibernateSession.Save(entity);) despite it being persisted to the database fine "Value cannot be null.\r\nParameter name: id" This is my hbm file <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="JeanieMaster.Domain.Entities" assembly="JeanieMaster.Domain"> <class name="ActionLog" table="ActionLog" schema="[DBSVR1].[mydatabase].[dbo]" select-before-update="false" optimistic-lock="none"> <id name="Id" column="ActionLogId" type="Int32"> <generator class="identity"/> </id> <property name="ActionId" type="Int32"/> <many-to-one name="User" class="JeanieUser" column="UserId" /> <many-to-one name="ApplicationProvider" class="ApplicationProvider" column="ApplicationProviderId" /> <many-to-one name="ContentProvider" class="ContentProvider" column="ContentProviderId" /> <many-to-one name="SearchLog" class="SearchLog" column="SearchLogId" /> <property name="Data" type="string"/> <property name="DateCreated" type="DateTime"/> <property name="ActionDuration" type="Double"/> </class> </hibernate-mapping>

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• Login in via curl then open that page logged in

  - by user207022

  I'm trying the following code to send post data to the login form, then reload that page in the browser as a logged in user. somehow it's not saving the cookie, and reusing it for the header() function, can the same thing as header be done by calling curl again after sending the login details? .. $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, $url); $ch = curl_init(); curl_setopt($ch, CURLOPT_URL,$url); curl_setopt($ch, CURLOPT_FOLLOWLOCATION,true); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_HEADER, true); curl_setopt($ch, CURLOPT_TIMEOUT, 60); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER , false ); curl_setopt($ch, CURLOPT_SSL_VERIFYHOST , false ); curl_setopt($ch, CURLOPT_USERAGENT, $defined_vars['HTTP_USER_AGENT']); //curl_setopt($ch, CURLOPT_COOKIEJAR, $cookie); curl_setopt($ch, CURLOPT_COOKIEFILE, $cookie); curl_setopt($ch, CURLOPT_MAXREDIRS, 1); // Apply the XML to our curl call curl_setopt($ch, CURLOPT_POST, 1); curl_setopt($ch, CURLOPT_POSTFIELDS, $data); $data = curl_exec($ch); setcookie($cookie); header('location: ' . $url); die();

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• Is NSManagedObjectContext autosaved or am I looking at NSFetchedResultsController's cache?

  - by Andreas

  I'm developing an iPhone app where I use a NSFetchedResultsController in the main table view controller. I create it like this in the viewDidload of the main table view controller: NSSortDescriptor *sortDescriptorDate = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES]; NSSortDescriptor *sortDescriptorTime = [[NSSortDescriptor alloc] initWithKey:@"start" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptorDate,sortDescriptorTime, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; [sortDescriptorDate release]; [sortDescriptorTime release]; [sortDescriptors release]; controller = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:context sectionNameKeyPath:@"date" cacheName:nil]; [fetchRequest release]; NSError *error; BOOL success = [controller performFetch:&error]; Then, in a subsequent view, I create a new object on the context: TestObject *testObject = [NSEntityDescription insertNewObjectForEntityForName:@"TestObject" inManagedObjectContext:context]; The TestObject has several related object which I create in the same way and add to the testObject using the provided add...Objects methods. Then, if before saving the context, I press cancel and go back to the main table view, nothing is shown as expected. However, if I restart the app, the object I created on the context shows in the main table view. How come? At first, I thought it was because the NSFetchedResultsController was reading from the cache, but as you can see I set this to nil just to test. Also, [context hasChanges] returns true after I restart. What am I missing here?

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• c++ issues with cin.fail() in my program

  - by Wallace

  I want to use input y to do saving thing,and r to do resuming, but then i write it in the following codes,and then I input y or r,I just to be noticed ""Please enter two positve numbers" this line code "if(x==(int)('y'))"and next line is ignored.how could this happen int main(){ cout<<"It's player_"<<player+1<<"'s turn please input a row and col,to save and exit,input 0,resume game input"<<endl; while(true){ cin>>x; if(x==(int)('y')) {save();has_saved=true;break;} if(x==(int)('r')) {resume();has_resumed=true;break;} cin>>y; if(cin.fail()){ cout<<"Please enter two positve numbers"<<endl; cin.clear(); cin.sync();} else if (x>n||x<1||y<1||y>n) { cout<<"your must input a positive number less or equal than "<<n<<endl; continue;} else if(chessboard[x][y]!=' ') {cout<<"Wrong input please try again!"<<endl; continue;} else { chessboard[x][y]=player_symbol[player+1]; break; } } }

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• How did your team customize Stylecop (and perhaps other tools) for .Net for a good result?

  - by Hamish Grubijan

  Our team is still in a love / hate relationship with it. I am hoping to put an end to the debate by having an internal vote on what rules should be excluded and which rules should be added. Before doing so, I wanted to ask others SO users. To standardize (but not limit) the responses: What is your current StyleCop version? What .Net version do you currently target? Which default rules did you turn off? Which non-default rules have you turned on? Have you coded your own rules? Please describe. Do you have any other StyleCop tricks worth sharing? Do you use Resharper? What version? Is it a good bang for the buck? Do you use any other tools for .Net / C++ which integrate with Visual Studio and aid development? Did you get your money's worth? Anything else you like to add? ... Thank you!

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• Implementing list position locator in C++?

  - by jfrazier

  I am writing a basic Graph API in C++ (I know libraries already exist, but I am doing it for the practice/experience). The structure is basically that of an adjacency list representation. So there are Vertex objects and Edge objects, and the Graph class contains: list<Vertex *> vertexList list<Edge *> edgeList Each Edge object has two Vertex* members representing its endpoints, and each Vertex object has a list of Edge* members representing the edges incident to the Vertex. All this is quite standard, but here is my problem. I want to be able to implement deletion of Edges and Vertices in constant time, so for example each Vertex object should have a Locator member that points to the position of its Vertex* in the vertexList. The way I first implemented this was by saving a list::iterator, as follows: vertexList.push_back(v); v->locator = --vertexList.end(); Then if I need to delete this vertex later, then rather than searching the whole vertexList for its pointer, I can call: vertexList.erase(v->locator); This works fine at first, but it seems that if enough changes (deletions) are made to the list, the iterators will become out-of-date and I get all sorts of iterator errors at runtime. This seems strange for a linked list, because it doesn't seem like you should ever need to re-allocate the remaining members of the list after deletions, but maybe the STL does this to optimize by keeping memory somewhat contiguous? In any case, I would appreciate it if anyone has any insight as to why this happens. Is there a standard way in C++ to implement a locator that will keep track of an element's position in a list without becoming obsolete? Much thanks, Jeff

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• NHibernate. DTO -> Domain

  - by Andrew Kalashnikov

  Hello guys. I've got SOA which processing data for diff clients(asp,sl). The base of this design is domains of my business model. For transporting,showing it to clients I use DTO. For mapping domain to DTO I use AutoMapper. Now I should persist new entities from clients. I want use my DTO's at this scenario too. So i've got some questions as I'm not much familiar with this design 1) Is it a good practice build DTO on client and send it to web-service on the wire? MayBe i should pass my domains? 2) Is it possible have several DTO's to one domain (one show at grid, and one to save). For saving I need set all nonprimitive props at client. 3) DTO - to Domain. If I've got int can I use AutoMapper to generate NHibernate Proxy for this ID, or I should do i manually. Your expierence and practice are very interesting. Thanks for answer!!!

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• how to check null value of Integer type field in ASP.NET MVC view?

  - by Vikas

  Hi, I have integer type field in database which is having property "Not Null". when i create a view & do a validation, if i left that field blank, it will consider it as 0 so i can not compare it with 0 because if someone insert a value 0 then it will be considered as error! one another problem is that i am using Model error as described in the book "ASP.NET MVC 1.0" @ Scott Gu blog. And I am checking the value in partial class of object (created by LINQ-To-SQL). i.e public partial class Person { public bool IsValid { get { return (GetRuleViolations().Count() == 0); } } public IEnumerable<RuleViolation> GetRuleViolations() { if (String.IsNullOrEmpty(Name)) yield return new RuleViolation("Name is Required", "Name"); if (Age == 0) yield return new RuleViolation("Age is Required", "Age"); yield break; } partial void OnValidate(ChangeAction action) { if (!IsValid) throw new ApplicationException("Rule violations prevent saving"); } } There is also problem with range. Like in database if i declared as smallint i.e. short in c#, now if i exceed that range then it gives error as "A Value is reguired". so finally is there any best way for validation in ASP.NET MVC?

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• Using Hibernate with MS ACCESS 2007 Database (Free JDBC Driver)

  - by Quentin T.

  1. I want to do a reverse engineering action with the Hibernate plugin of Eclipse on a MS Access 2007 Database. I'm forced to use a existing MS Access 2007 db. A easy solution is to buy the HXTT. But I want to use a free driver to do my work. So I tried to apply this post : http://www.programmingforfuture.com/2011/06/how-to-use-ms-access-with-hibernate.html (That uses the SQL Server dialect and the driver sun.jdbc.odbc.JdbcOdbcDriver) Unfortunately I have an error that nobody seems to have been on the internet: Exception while generating code Reason : org.hibernate.exception.GenericJDBCException: Error while reading primary key meta data for `c:/myaccessdb.mdb`.TableTest1 I have try to change the primary key on my MS Access DB (deleting all primary key) or to try the reverse engineering on a MS ACCESS with only one table without primary key, but I got all times the problems. 2. The purpose of my job is to transfer daily (weekly) an Oracle 11g database with data from an existing database MS ACCESS 2007. And I thought to use a procedure (Hibernate EJB) Java to be launched automatically every week to do the data transfer. Is this is the best solution ? Configuration : sun.jdbc.odbc.JdbcOdbcDriver v??? Hibernate v3.4 Eclipse ps: If you are a HXTT developer or seller please be indulgent with my post ;). Making money by making people believe that you help, it's bad ! A solution is to use Derby Client driver, as the solution in the post: Does anyone know if Hibernate and java will work effectively with Access? But a clarification of the answer of Rich Seller is required. Could you explain your answer and explain your configuration (hibernate.cfg.xml, persistence.xml and what URL you use in the property name="hibernate.connection.url") without using paying HXTT driver but with the free Derby driver.

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• Use GIS to get geographic info for a single point

  - by Patrick Scott

  I am not quite sure where to start with this. I only just started looking into this in the past week, but hopefully someone can help point me in the right direction. The goal of my project is to be able to take a geohash, decode it to latitude and longitude, check the point against some GIS data, and find out some information about that point such as the terrain(is this a body of water? A lake? An Ocean? Is this a mountainous area? Is this a field?), altitude, or other useful things. Then simply be able to display that information as a starter. What I have gathered so far is that I need to get some free GIS data (this is for school, so I have no money!). I would like to have world data, and I found some online (http://www.webgis.com/terraindata.html) but I don't know where to go from here. I saw some tools such as PostGIS as a database. I am currently using Java for some other parts of the project, so if possible I would like to stick to Java. Can someone help me out, or point me in the right direction?

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