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  • Type contraint problem of C#

    - by user351565
    I meet a problem about type contraint of c# now. I wrote a pair of methods that can convert object to string and convert string to object. ex. static string ConvertToString(Type type, object val) { if (type == typeof(string)) return (string)val; if (type == typeof(int)) return val.ToString(); if (type.InSubclassOf(typeof(CodeObject))) return ((CodeObject)val).Code; } static T ConvertToObject<T>(string str) { Type type = typeof(T); if (type == typeof(string)) return (T)(object)val; if (type == typeof(int)) return (T)(object)int.Parse(val); if (type.InSubclassOf(typeof(CodeObject))) return Codes.Get<T>(val); } where CodeObject is a base class of Employees, Offices ..., which can fetch by static method Godes.Get where T: CodeObject but the code above cannot be compiled because error #CS0314 the generic type T of method ConvertToObject have no any constraint but Codes.Get request T must be subclass of CodeObject i tried use overloading to solve the problem but not ok. is there any way to clear up the problem? like reflection?

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  • Monotouch auto resizing views in iphone

    - by Tim Bassett
    I have created a view in interface builder that contains another view (content area) and a button bar at the bottom. The hierarchy is as: ->View --->mapContainer UIView ----->map MKMapView ----->OverlayView UIView --->ToolBar UIToolBar I would like the mapContainer to resize to full window when the ToolBar is hidden. I would like the map and the OverlayView to resize to the mapContainer size I have attempted the following code, but it has no effect. Please advise? public override void ViewDidLoad () { base.ViewDidLoad (); this.mapContainer.AutosizesSubviews = true ; this.View.AutosizesSubviews = true ; try { this.mapContainer.AutoresizingMask = UIViewAutoresizing.FlexibleHeight | UIViewAutoresizing.FlexibleWidth ; this.map.AutoresizingMask = UIViewAutoresizing.FlexibleHeight | UIViewAutoresizing.FlexibleWidth ; this.map.SizeToFit(); this.mapContainer.SizeToFit(); this.map.SizeToFit(); this.View.Frame = new System.Drawing.RectangleF(0,0,this.View.Frame.Width, this.View.Frame.Height ); this.mapContainer.LayoutSubviews(); } catch(Exception ex) { Console.Write(ex.ToString()); } }

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  • Ruby on Rails or PHP... Somehow uncertain

    - by Clamm
    Hi everybody... I've been thinking about this a long time now but i wanna hear your opinion because i always received the ebst answers here. So in advance... thank you guys. Right now i have to make this decision: Shift a prototype webservice to production quality. Choose either Ruby or PHP... (Background: A friend of mine is joining the project and prefers rails) I've already played around a bit with RoR (only basic stuff) but i am really disappointed about the documentation of Rails and Ruby. In relation to PHP i find only fragments or hard to use references. At the end i am a bit scared. I dont wanna waste my time realizing that i am not capable of doing s.th in Ruby what i could with PHP. Maybe only because i am too stupid and don't find a proper explanation ;-) Did anyone experience this shift and can tell me how easy/hard it was to switch from PHP to Ruby? E.G. would you recommend programming it in PHP and using MVC as a base pattern? Thanks for your opinion!!!

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  • when is a v-table created in C++?

    - by saminny
    When exactly does the compiler create a virtual function table? 1) when the class contains at least one virtual function. OR 2) when the immediate base class contains at least one virtual function. OR 3) when any parent class at any level of the hierarchy contains at least one virtual function. A related question to this: Is it possible to give up dynamic dispatch in a C++ hierarchy? e.g. consider the following example. #include <iostream> using namespace std; class A { public: virtual void f(); }; class B: public A { public: void f(); }; class C: public B { public: void f(); }; Which classes will contain a V-Table? Since B does not declare f() as virtual, does class C get dynamic polymorphism?

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  • Generate Spring bean definition from a Java object

    - by joeslice
    Let's suggest that I have a bean defined in Spring: <bean id="neatBean" class="com..." abstract="true">...</bean> Then we have many clients, each of which have slightly different configuration for their 'neatBean'. The old way we would do it was to have a new file for each client (e.g., clientX_NeatFeature.xml) that contained a bunch of beans for this client (these are hand-edited and part of the code base): <bean id="clientXNeatBean" parent="neatBean"> <property id="whatever" value="something"/> </bean> Now, I want to have a UI where we can edit and redefine a client's neatBean on the fly. My question is: given a neatBean, and a UI that can 'override' properties of this bean, what would be a straightforward way to serialize this to an XML file as we do [manually] today? For example, if the user set property whatever to be "17" for client Y, I'd want to generate: <bean id="clientYNeatBean" parent="neatBean"> <property id="whatever" value="17"/> </bean> Note that moving this configuration to a different format (e.g., database, other-schema'd-xml) is an option, but not really an answer to the question at hand.

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  • EventKitUI view and edit problem!

    - by Alish
    I try to to find a solution to do View and Edit of a the item from a tablview. My application base on UITabBarController. Each of the Bar items contain a class with a a couple of UIViews. This is the first items of UITabBarController. I done Add event from Apple sample code: SimpleEKDemo. Add Event working without any problem. I tried to add View and Edit part to the code. I would able to select an items from tableView to edit the selected item. But after I tried to add code from SimpleEKDemo to my code, I realized I have to add UINavigationController to the implement. So I did. After I add that it's came to the items of UITabBarController. Also I even the Add Event didn't worked very well (I couldn't insert event name and location. but edit was working. So I need to know: 1- Is it possible to implement Edit/View without using UINavigationController. If yes please let me know a sample code. 2- If I must use UINavigationController. Because I don't need UINavigationController to become it the first page and I don't need any bar added to my application. Is it possible it's appear in the application when I choose a item of tableView but appear alike that! Snapshots: https://public.me.com/alish (pict.zip)

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  • WPF Databinding With A Collection Object

    - by Randster
    Argh, although I've been googling, I really would appreciate it if someone could break my problem down as all the code examples online are confusing me more than assisting (perhaps it's just late)... I have a simple class as defined below: public class Person { int _id; string _name; public Person() { } public int ID { get { return _id; } set { _id = value; } } public string Name { get { return _name; } set { _name = value; } } } that is stored in a database, and thru a bit more code I put it into an ObservableCollection object to attempt to databind in WPF later on: public class People : ObservableCollection<Person> { public People() : base() { } public void Add(List<Person> pListOfPeople) { foreach (Person p in pListOfPeople) this.Add(p); } } In XAML, I have myself a ListView that I would like to populate a ListViewItem (consisting of a textblock) for each item in the "People" object as it gets updated from the database. I would also like that textblock to bind to the "Name" property of the Person object. I thought at first that I could do this: lstPeople.DataContext = objPeople; where lstPeople is my ListView control in my XAML, but that of course does nothing. I've found TONS of examples online where people through XAML create an object and then bind to it through their XAML; but not one where we bind to an instantiated object and re-draw accordingly. Could someone please give me a few pointers on: A) How to bind a ListView control to my instantiated "People" collection object? B) How might I apply a template to my ListView to format it for the objects in the collection? Even links to a decent example (not one operating on an object declared in XAML please) would be appreciated. Thanks for your time.

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  • Creating a image viewer window controll.

    - by Scott Chamberlain
    I am learning GDI+ and I am trying to make a display window with scroll bars (so I can only see part of the image at a time and I can scroll around it). I have read through the basics of GDI+ from several books but I have not found any good tutorials online or in books available to me about doing more advanced things like this. Any recommendations on guides or example code on how do do this? Here is what I have so far protected override void OnPaint(PaintEventArgs e) { base.OnPaint(e); if (Label != null) { using (Bitmap drawnLabel = new Bitmap(Label.LabelHeight, Label.LableLength, System.Drawing.Imaging.PixelFormat.Format1bppIndexed)) using (Graphics drawBuffer = Graphics.FromImage(drawnLabel)) { drawBuffer.ScaleTransform(_ImageScaleFactor, _ImageScaleFactor); foreach (Epl2.IDrawableCommand cmd in Label.Collection) { cmd.Paint(drawBuffer); } drawBuffer.ResetTransform(); } } } I would like to paint this in to a PictureBox I have on the control and control what is shown by a VScrollBar and HScrollBar but I don't know how to do that step. P.S. Label is a custom class that I have in my namespace, it is a object that represents a label you would print from a label printer.

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  • (closed) nodejs responding an image (via pipe and response.end()) leads into strange behaviour

    - by johannesboyne
    What the Problem was: I had 2 different writeStreams! If WriteStram#1 is closed, the second should be closed too and then it all should be piped... BUT node is asynchronious so while one has been closed, the other one hasn't. Even the stream.end() was called... well you always should wait for the close event! thx guys for your help! I am at my wit's end. I used this code to pipe an image to my clients: req.pipe(fs.createReadStream(__dirname+'/imgen/cached_images/' + link).pipe(res)) it does work but sometimes the image is not transferred completely. But no error is thrown neither on client side (browser) nor on server side (node.js). My second try was var img = fs.readFileSync(__dirname+'/imgen/cached_images/' + link); res.writeHead(200, { 'Content-Type' : 'image/png' }); res.end(img, 'binary'); but it leads to the same strange behaviour... Does anyone got a clue for me? Regards! (abstracted code...) var http = require('http'); http.createServer(function (req, res) { Imgen.generateNew( 'virtualtwins/www_leonardocampus_de/overview/28', 'www.leonardocampus.de', 'overview', '28', null, [], [], function (link) { fs.stat(__dirname+'/imgen/cached_images/' + link, function(err, file_info) { if (err) { console.log('err', err); } console.log('file info', file_info.size); res.writeHead(200, 'image/png'); fs.createReadStream(__dirname+'/imgen/cached_images/' + link).pipe(res); }); } ); }).listen(13337, '127.0.0.1'); Imgen.generateNew just creates a new file, saves it to the disk and gives back the path (link)

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  • why the exception is not caught?

    - by Álvaro García
    I have the following code: List<MyEntity> lstAllMyRecords = miDbContext.MyEntity.ToList<MyEntity>(); foreach MyEntity iterator in lstMainRecord) { tasks.Add( TaskEx.Run(() => { try { checkData(lstAllMyRecords.Where(n => n.IDReference == iterator.IDReference).ToList<MyEntity>()); } catch CustomRepository ex) { //handle my custom repository } catch (Exception) { throw; } }) ); }//foreach Task.WaitAll(tasks.ToArray()); I get all the records from my data base and in the foreach loop, I group all the records that have the same IDReference. Thenk I check if the data is correct with the method chekData. The checkData method throw a custom exception if something is wrong. I would like to catch this exception to handle it. But the problem is that with this code the exceptions are not caught and all seem to work without errors, but I know that this is not true. I try to check only one group of records that I know that has problems. If I check only one group of registrers, the loop is execute once and then only task is created. In this case the exception is caught, but if I have many groups, then any exception s thrwon. Why when I only have one task the exception is caught and with many groups are not? Thanks.

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  • Do I need to echo html inside included php file

    - by UmeRonaldo
    I just learned how to include php .Here's the index or main php file <!DOCTYPE HTML> <html> <head> </head> <body> <?php include 'header.php'; ?> </body> </html> now in header.php file which way is better to print html Way 1 directly use html without php <header> <h1>Header</h1> </header> Way 2 Using php and echo <?php echo ' <header> <h1>Header</h1> </header> ' ?> Another quick question. Will it work if I use .html for the base or index file ?? sorry for my bad english

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  • How to implement the disposable pattern in a class that inherits from another disposable class?

    - by TheRHCP
    Hi, I often used the disposable pattern in simple classes that referenced small amount of resources, but I never had to implement this pattern on a class that inherits from another disposable class and I am starting to be a bit confused in how to free the whole resources. I start with a little sample code: public class Tracer : IDisposable { bool disposed; FileStream fileStream; public Tracer() { //Some fileStream initialization } public void Dispose() { this.Dispose(true); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { if (!disposed) { if (disposing) { if (fileStream != null) { fileStream.Dispose(); } } disposed = true; } } } public class ServiceWrapper : Tracer { bool disposed; ServiceHost serviceHost; //Some properties public ServiceWrapper () { //Some serviceHost initialization } //protected override void Dispose(bool disposing) //{ // if (!disposed) // { // if (disposing) // { // if (serviceHost != null) // { // serviceHost.Close(); // } // } // disposed = true; // } //} } My real question is: how to implement the disposable pattern inside my ServiceWrapper class to be sure that when I will dispose an instance of it, it will dispose resources in both inherited and base class? Thanks.

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  • problem after uploading file to web host

    - by Alexander
    I have a .xml file in my App_Data folder, I can access it fine in my localhost, however after uploading it to my webhost I got the following: ASP.NET is not authorized to access the requested resource. Consider granting access rights to the resource to the ASP.NET request identity. ASP.NET has a base process identity (typically {MACHINE}\ASPNET on IIS 5 or Network Service on IIS 6) that is used if the application is not impersonating. If the application is impersonating via , the identity will be the anonymous user (typically IUSR_MACHINENAME) or the authenticated request user. To grant ASP.NET access to a file, right-click the file in Explorer, choose "Properties" and select the Security tab. Click "Add" to add the appropriate user or group. Highlight the ASP.NET account, and check the boxes for the desired access. So who should I grant access to read? There's 3 user in my web host and all seems to have read access set to them.. one is NETWORK_SERVICE, IUSR_MACHINENAME and my user. So what is wrong?

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  • Comparing lists of field-hashes with equivalent AR-objects.

    - by Tim Snowhite
    I have a list of hashes, as such: incoming_links = [ {:title => 'blah1', :url => "http://blah.com/post/1"}, {:title => 'blah2', :url => "http://blah.com/post/2"}, {:title => 'blah3', :url => "http://blah.com/post/3"}] And an ActiveRecord model which has fields in the database with some matching rows, say: Link.all => [<Link#2 @title='blah2' @url='...post/2'>, <Link#3 @title='blah3' @url='...post/3'>, <Link#4 @title='blah4' @url='...post/4'>] I'd like to do set operations on Link.all with incoming_links so that I can figure out that <Link#4 ...> is not in the set of incoming_links, and {:title => 'blah1', :url =>'http://blah.com/post/1'} is not in the Link.all set, like so: #pseudocode #incoming_links = as above links = Link.all expired_links = links - incoming_links missing_links = incoming_links - links expired_links.destroy missing_links.each{|link| Link.create(link)} One route I've tried: I'd rather not rewrite Array#- and such, and I'm okay with converting incoming_links to a set of unsaved Link objects; so I've tried overwriting hash eql? and so on in Link so that it ignored the id equality that AR::Base provides by default. But this is the only place this sort of equality should be considered in the application - in other places the Link#id default identity is required. Is there some way I could subclass Link and apply the hash, eql?, etc overwriting there? The other route I've tried is to pull out the attributes hash for each Link and doing a .slice('id',...etc) to prune the hashes down. But this requires writing seperate methods for keeping track of the Link objects while doing set operations on the hashes, or writing seperate Collection classes to wrap the incoming_links hash-list and Link-list which seems a bit overkill. What is the best way to design this interaction? Extra credit for cleanliness.

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  • free( ) pointers

    - by user1043625
    I'm required to use a special library to keep track of my memory leaks where malloc()= allocate( ) and free( ) = unallocate( ). I'm trying to complete free a linked-list but it seems like the "root" value isn't being freed. typedef struct _node { struct _node *child; char *command; } Command_list; void delete_commands(Command_list **root) { Command_list *temp; while( *root != NULL ){ temp = (*root)->child; //printf("STRING: %s\n", *root->command ); unallocate( *root ); *root = temp; } } The function that's calling it void file_processing( .... ){ Command_list *root = allocate(sizeof (Command_list)); root = NULL; .... delete_commands( &root ); } } I believe that Command_list *root = allocate(sizeof (Command_list)) isn't being properly de-allocated for some reason. Anyone can give me some hints? UPDATE: I found out that instead of Command_list *root = allocate(sizeof (Command_list)); root = NULL; this works: Command_list *root = NULL;

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  • Is inheritance bad nowadays?

    - by mafutrct
    Personally, I think inheritance is a great tool, that, when applied reasonably, can greatly simplify code. However, I seems to me that many modern tools dislike inheritance. Let's take a simple example: Serialize a class to XML. As soon as inheritance is involved, this can easily turn into a mess. Especially if you're trying to serialize a derived class using the base class serializer. Sure, we can work around that. Something like a KnownType attribute and stuff. Besides being an itch in your code that you have to remember to update every time you add a derived class, that fails, too, if you receive a class from outside your scope that was not known at compile time. (Okay, in some cases you can still work around that, for instance using the NetDataContract serializer in .NET. Surely a certain advancement.) In any case, the basic principle still exists: Serialization and inheritance don't mix well. Considering the huge list of programming strategies that became possible and even common in the past decade, I feel tempted to say that inheritance should be avoided in areas that relate to serialization (in particular remoting and databases). Does that make sense? Or am messing things up? How do you handle inheritance and serialization?

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  • error in a c code while trying to remove whitespace

    - by mekasperasky
    this code is the base of lexer , and it does the basic operation of removing the whitespaces from a source file and rewrites it into another file with each word in separate lines . But i am not able to understand why the file lext.txt not getting updated? #include<stdio.h> /* this is a lexer which recognizes constants , variables ,symbols, identifiers , functions , comments and also header files . It stores the lexemes in 3 different files . One file contains all the headers and the comments . Another file will contain all the variables , another will contain all the symbols. */ int main() { int i; char a,b[20],c; FILE *fp1,*fp2; fp1=fopen("source.txt","r"); //the source file is opened in read only mode which will passed through the lexer fp2=fopen("lext.txt","w"); //now lets remove all the white spaces and store the rest of the words in a file if(fp1==NULL) { perror("failed to open source.txt"); //return EXIT_FAILURE; } i=0; while(!feof(fp1)) { a=fgetc(fp1); if(a!="") { b[i]=a; printf("hello"); } else { b[i]='\0'; fprintf(fp2, "%.20s\n", b); i=0; continue; } i=i+1; /*Switch(a) { case EOF :return eof; case '+':sym=sym+1; case '-':sym=sym+1; case '*':sym=sym+1; case '/':sym=sym+1; case '%':sym=sym+1; case ' */ } return 0; }

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  • pathogen#infect not updating the runtimepath

    - by Taylor Price
    I have started working with pathogen.vim with gvim on Windows, following Tim Pope's setup guide at his github repository here. However, I'm running into the problem that pathogen#infect() does not seem to be modifying the runtimepath (as seen by running :echo &runtimepath in gvim). The simple test case _vimrc that I came up with is as follows. Please note that pathogen gets loaded just fine. "Set a base directory. let $BASE_DIR='H:\development\github\vimrc' "Source pathogen since it's not in the normal autoload directory. source $BASE_DIR\autoload\pathogen.vim "Start up pathogen call pathogen#infect() "call pathogen#infect('$BASE_DIR\functions') Neither running pathogen#infect() without an argument (which should add the bundles directory under the vimfiles directory) nor specifying a directory to contain files works. Substituting the pathogen#infect() call with pathogen#runtime_prepend_subdirectories('$BASE_DIR\functions'), which is what pathogen#infect() does fails to change the runtimepath as well. Any ideas that I've missed? Any more information that would be helpful? My repository with the non-trivial example is here.

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  • Rails: Duplicate functionality across controllers? A humble plea.

    - by Alex
    So I'm working with authlogic, and I'm trying to duplicate the login functionality to the welcome page, so that you can log in by restful url or by just going to the main page. No, I don't know if we'll keep that feature, but I want to test it out anyway. Here's the error message: RuntimeError in Welcome#index Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id The code is below. Basically, what's happening is the index view (the first code snippet) is sending the information from the form to the create method of user_sessions controller. At this point, in theory, it create should just pick up, but it doesn't. PLEASE help. Please. I've been doing this for about 8 hours. I checked Google. I checked IRC. I checked every book I could find. You don't even have to answer, I can to the grunt work if you just point me in the right direction. <% form_for @user_session, :url => user_sessions_path do |f| %> <%= f.text_field :email %><br /> <%= f.password_field :password %> <%= submit_tag 'Login' %> <% end %> class ApplicationController < ActionController::Base helper :all # include all helpers, all the time protect_from_forgery # See ActionController::RequestForgeryProtection for details # Scrub sensitive parameters from your log # filter_parameter_logging :password helper_method :current_user_session, :current_user before_filter :new_session_object protected def new_session_object unless current_user @user_session = UserSession.new(params[:user_session]) end end private def current_user_session return @current_user_session if defined?(@current_user_session) @current_user_session = UserSession.find end def current_user return @current_user if defined?(@current_user) @current_user = current_user_session && current_user_session.record end end

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  • implementing user tracking (logging) in Rails 3

    - by seth.vargo
    Hi, I'm creating a Rails application in which logging individual user actions is vital. Every time a user clicks a url, I want to log the action along with all parameters. Here is my current implementation: class CreateActivityLogs < ActiveRecord::Migration create_table :activity_logs do |t| t.references :user t.string :ip_address t.string :referring_url t.string :current_url t.text :params t.text :action t.timestamps end end   class ActivityLog < ActiveRecord::Base belongs_to :user end In a controller, I'd like to be able to do something like the following: ... ActivityLog::log @user.id, params, 'did foo with bar' ... I'd like to have the ActivityLog::log method automatically get the IP address, referring url, and current url (I know how to do this already) and create a new record in the table. So, my questions are: How do I do this? How do I use ActivityLog without having to create an instance everytime I want to log? Is this the best way? Some people have argued for a flat-file log for this kind of logging - however, I want admins to be able to see a user's activity in the backend as well, so I thought a database solution may be better?

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  • Why does false invalidate validates_presence_of?

    - by DJTripleThreat
    Ok steps to reproduce this: prompt> rails test_app prompt> cd test_app prompt> script/generate model event_service published:boolean then go into the migration and add not null and default published to false: class CreateEventServices < ActiveRecord::Migration def self.up create_table :event_services do |t| t.boolean :published, :null => false, :default => false t.timestamps end end def self.down drop_table :event_services end end now migrate your changes and run your tests: prompt>rake db:migrate prompt>rake You should get no errors at this time. Now edit the model so that you validate_presence_of published: class EventService < ActiveRecord::Base validates_presence_of :published end Now edit the unit test event_service_test.rb: require 'test_helper' class EventServiceTest < ActiveSupport::TestCase test "the truth" do e = EventServer.new e.published = false assert e.valid? end end and run rake: prompt>rake You will get an error in the test. Now set e.published to true and rerun the test. IT WORKS! I think this probably has something to do with the field being boolean but I can't figure it out. Is this a bug in rails? or am I doing something wrong?

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  • Unnecessary Redundancy with Tables.

    - by Stacey
    My items are listed as follows; This is just a summary of course. But I'm using a method shown for the "Detail" table to represent a type of 'inheritence', so to speak - since "Item" and "Downloadable" are going to be identical except that each will have a few additional fields relevant only to them. My question is in this design pattern. This sort of thing appears many, many times in our projects - is there a more intelligent way to handle it? I basically need to normalize the tables as much as possible. I'm extremely new to databases and so this is all very confusing to me. There are 5 items. Awards, Items, Purchases, Tokens, and Downloads. They are all very, very similar, except each has a few pieces of data relevant only to itself. I've tried to use a declaration field (like an enumerator 'Type' field) in conjunction with nullable columns, but I was told that is a bad approach. What I have done is take everything similar and place it in a single table, and then each type has its own table that references a column in the 'base' table. The problem occurs with relationships, or junctions. Linking all of these back to a customer. Each type takes around 2 additional tables to properly junction all of the data together- and as such, my database is growing very, very large. Is there a smarter practice for this kind of behavior? Item ID | GUID Name | varchar(64) Product ID | GUID Name | varchar(64) Store | GUID [ FK ] Details | GUID [FK] Downloadable ID | GUID Name | varchar(64) Url | nvarchar(2048) Details | GUID [FK] Details ID | GUID Price | decimal Description | text Peripherals [ JUNCTION ] ID | GUID Detail | GUID [FK] Store ID | GUID Addresses | GUID Addresses ID | GUID Name | nvarchar(64) State | int [FK] ZipCode | int Address | nvarchar(64) State ID | int Name | varchar(32)

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  • A scheme to show picture

    - by luoliyong
    I have a requirement that need me to show picture using one canvas. All the operation will be done on this canvas, include change the picture (This picture is made of lines, rectangular and so on. Draw these lines or rectangular will use the base method). In China, we called use double buffer(CGBitmapContextCreate), one of the scheme like this // create the bitmap context CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef context = CGBitmapContextCreate(nil,27,27,8,0, colorSpace,kCGImageAlphaPremultipliedLast); CFRelease(colorSpace); Maybe now it is not very clear. I talk about the project. The project has an engine, That will call methed draw line, draw round ,draw rectangular according user's input, this lines, rounds, rectangular will make up a picture? and then usr changes his input, the picture also will change, the engine accept usr's input, and draw picture. and the engine inits only once. I hope you can understand what I say, and give me some advice. Thanks.

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  • [C#] How do I make hierarchy of objects from two alternating classes?

    - by Millicent
    Here's the scenario: I have two classes ("Page" and "Field"), that are descended from a common class ("Pield"). They represent tags in an XML file and are in the following hierarchy: <page> <field> <page> ... </page> ... </field> ... </page> I.e.: Page and Field objects are in a hierarchy of alternating type (there may be more than one Page or Field to each rung of the hierarchy). Every Field and Page object has a parent property, which points to the respective parent object of the other type. This is not a problem unless the parent-child mechanism is controlled by the base class (Pield), which is shared by the two descended classes (Page and Field). Here is one try, that fails at the line "Pield child = new Pield(pchild, this);": class Pield<T> { private T _pield_parent; ... private void get_children() { ... Pield<Page> child = new Pield<Page>(pchild, this); ... } ... } class Page : Pield<Field> { ... } class Field : Pield<Page> { ... } Any ideas about how to solve this elegantly? Best, Millicent

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  • interface abstract in php real world scenario

    - by jason
    The goal is to learn whether to use abstract or interface or both... I'm designing a program which allows a user to de-duplicate all images but in the process rather then I just build classes I'd like to build a set of libraries that will allow me to re-use the code for other possible future purposes. In doing so I would like to learn interface vs abstract and was hoping someone could give me input into using either. Here is what the current program will do: recursive scan directory for all files determine file type is image type compare md5 checksum against all other files found and only keep the ones which are not duplicates Store total duplicates found at the end and display size taken up Copy files that are not duplicates into folder by date example Year, Month folder with filename is file creation date. While I could just create a bunch of classes I'd like to start learning more on interfaces and abstraction in php. So if I take the scan directory class as the first example I have several methods... ScanForFiles($path) FindMD5Checksum() FindAllImageTypes() getFileList() The scanForFiles could be public to allow anyone to access it and it stores in an object the entire directory list of files found and many details about them. example extension, size, filename, path, etc... The FindMD5Checksum runs against the fileList object created from scanForFiles and adds the md5 if needed. The FindAllImageTypes runs against the fileList object as well and adds if they are image types. The findmd5checksum and findallimagetypes are optionally run methods because the user might not intend to run these all the time or at all. The getFileList returns the fileList object itself. While I have a working copy I've revamped it a few times trying to figure out whether I need to go with an interface or abstract or both. I'd like to know how an expert OO developer would design it and why?

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