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  • What is the best way to store static data in C# that will never changes

    - by Luke101
    I have a class that stores data in asp.net c# application that never changes. I really don't want to put this data in the database - I would like it to stay in the application. Here is my way to store data in the application: public class PostVoteTypeFunctions { private List<PostVoteType> postVotes = new List<PostVoteType>(); public PostVoteTypeFunctions() { PostVoteType upvote = new PostVoteType(); upvote.ID = 0; upvote.Name = "UpVote"; upvote.PointValue = PostVotePointValue.UpVote; postVotes.Add(upvote); PostVoteType downvote = new PostVoteType(); downvote.ID = 1; downvote.Name = "DownVote"; downvote.PointValue = PostVotePointValue.DownVote; postVotes.Add(downvote); PostVoteType selectanswer = new PostVoteType(); selectanswer.ID = 2; selectanswer.Name = "SelectAnswer"; selectanswer.PointValue = PostVotePointValue.SelectAnswer; postVotes.Add(selectanswer); PostVoteType favorite = new PostVoteType(); favorite.ID = 3; favorite.Name = "Favorite"; favorite.PointValue = PostVotePointValue.Favorite; postVotes.Add(favorite); PostVoteType offensive = new PostVoteType(); offensive.ID = 4; offensive.Name = "Offensive"; offensive.PointValue = PostVotePointValue.Offensive; postVotes.Add(offensive); PostVoteType spam = new PostVoteType(); spam.ID = 0; spam.Name = "Spam"; spam.PointValue = PostVotePointValue.Spam; postVotes.Add(spam); } } When the constructor is called the code above is ran. I have some functions that can query the data above too. But is this the best way to store information in asp.net? if not what would you recommend?

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  • Usage Rails 3.0 beta 3 without ActiveRecoord ORM

    - by Anton
    Hi everybody! Just installed Rails 3.0 beta 3 in Windows 7. And started playing with some easy examples class SignupController < ApplicationController def index @user = User.new(params[:user]) if method.post? and @user.save redirect_to :root end end end class User def initialize(params = {}) @email = params[:email] @passw = params[:passw] end def save end end <div align="center"> <% form_for :user do |form| %> <%= form.label :email %> <%= form.text_field :email %><br /> <%= form.label :password %> <%= form.text_field :password %><br /> <%= form.submit :Register! %> <% end %> </div> When I go to /signup I'm getting this error NoMethodError in SignupController#index You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil.[] Is there a problem with constructor or what's wrong?Please, need your help!

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  • java phone number validation....

    - by user69514
    Here is my problem: Create a constructor for a telephone number given a string in the form xxx-xxx-xxxx or xxx-xxxx for a local number. Throw an exception if the format is not valid. So I was thinking to validate it using a regular expression, but I don't know if I'm doing it correctly. Also what kind of exception would I have to throw? Do I need to create my own exception? public TelephoneNumber(String aString){ if(isPhoneNumberValid(aString)==true){ StringTokenizer tokens = new StringTokenizer("-"); if(tokens.countTokens()==3){ areaCode = Integer.parseInt(tokens.nextToken()); exchangeCode = Integer.parseInt(tokens.nextToken()); number = Integer.parseInt(tokens.nextToken()); } else if(tokens.countTokens()==2){ exchangeCode = Integer.parseInt(tokens.nextToken()); number = Integer.parseInt(tokens.nextToken()); } else{ //throw an excemption here } } } public static boolean isPhoneNumberValid(String phoneNumber){ boolean isValid = false; //Initialize reg ex for phone number. String expression = "(\\d{3})(\\[-])(\\d{4})$"; CharSequence inputStr = phoneNumber; Pattern pattern = Pattern.compile(expression); Matcher matcher = pattern.matcher(inputStr); if(matcher.matches()){ isValid = true; } return isValid; } Hi sorry, yes this is homework. For this assignments the only valid format are xxx-xxx-xxxx and xxx-xxxx, all other formats (xxx)xxx-xxxx or xxxxxxxxxx are invalid in this case. I would like to know if my regular expression is correct

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  • C++ - Need to learn some basics in a short while

    - by Rubys
    For reasons I will spare you, I have two weeks to learn some C++. I can learn alone just fine, but I need a good source. I don't think I have time to go through an entire book, and so I need some cliff notes, or possibly specific chapters/specialized resources I need to look up. I know my Asm/C/C# well, and so anything inherited from C, or any OOP is not needed. What I do need is some sources on the following subjects(I have a page that specifies what is needed, this is basically it, but I trimmed what I know): new/delete in C++ (as opposed to C#). Overloading cin/cout. Constructor, Destructor and MIL. Embedded Objects. References. Templates. If you feel some basic C++ concept that is not shared with C/C# is not included on this list, feel free to enter those as well. But the above subjects are the ones I'm supposed to roughly know in two week's time. Any help would be appreciated, thanks.

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  • Can a custom MFC window/dialog be a template class?

    - by John
    There's a bunch of special macros that MFC uses when creating dialogs, and in my quick tests I'm getting weird errors trying to compile a template dialog class. Is this likely to be a big pain to achieve? Here's what I tried: MyDlg.h template <class W> class CMyDlg : public CDialog { typedef CDialog super; DECLARE_DYNAMIC(CMyDlg <W>) public: CMyDlg (CWnd* pParent); // standard constructor virtual ~CMyDlg (); // Dialog Data enum { IDD = IDD_MYDLG }; protected: virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support DECLARE_MESSAGE_MAP() private: W *m_pWidget; //W will always be a CDialog }; IMPLEMENT_DYNAMIC(CMyDlg<W>, super) <------------------- template <class W> CMyDlg<W>::CMyDlg(CWnd* pParent) : super(CMyDlg::IDD, pParent) { m_pWidget = new W(this); } I get a whole bunch of errors but main one appears to be: error C2955: 'CMyDlg' : use of class template requires template argument list I tried using some specialised template versions of macros but it doesn't help much, other errors change but this one remains. Note my code is all in one file, since C++ templates don't like .h/.cpp like normal.

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  • Cannot make a static reference to the non-static type MyRunnable

    - by kaiwii ho
    Here is the whole code : import java.util.ArrayList; public class Test{ ThreadLocal<ArrayList<E>>arraylist=new ThreadLocal<ArrayList<E>>(){ @Override protected ArrayList<E> initialValue() { // TODO Auto-generated method stub //return super.initialValue(); ArrayList<E>arraylist=new ArrayList<E>(); for(int i=0;i<=20;i++) arraylist.add((E) new Integer(i)); return arraylist; } }; class MyRunnable implements Runnable{ private Test mytest; public MyRunnable(Test test){ mytest=test; // TODO Auto-generated constructor stub } @Override public void run() { System.out.println("before"+mytest.arraylist.toString()); ArrayList<E>myarraylist=(ArrayList<E>) mytest.arraylist.get(); myarraylist.add((E) new Double(Math.random())); mytest.arraylist.set(myarraylist); System.out.println("after"+mytest.arraylist.toString()); } // TODO Auto-generated method stub } public static void main(String[] args){ Test test=new Test<Double>(); System.out.println(test.arraylist.toString()); new Thread(new MyRunnable(test)).start(); new Thread(new MyRunnable(test)).start(); System.out.println(arraylist.toString()); } } my questions are: 1\ why the new Thread(new MyRunnable(test)).start(); cause the error: Cannot make a static reference to the non-static type MyRunnable ? 2\ what is the static reference refer to right here? thx in advanced

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  • How to throw meaningful data in exceptions ?

    - by ZeroCool
    I would like to throw exceptions with meaningful explanation ! I thought of using variable arguments worked fine but lately I figured out it's impossible to extend the class in order to implement other exception types. So I figured out using an std::ostreamstring as a an internal buffer to deal with formatting ... but doesn't compile! I guess it has something to deal with copy constructors. Anyhow here is my piece of code: class Exception: public std::exception { public: Exception(const char *fmt, ...); Exception(const char *fname, const char *funcname, int line, const char *fmt, ...); //std::ostringstream &Get() { return os_ ; } ~Exception() throw(); virtual const char *what() const throw(); protected: char err_msg_[ERRBUFSIZ]; //std::ostringstream os_; }; The variable argumens constructor can't be inherited from! this is why I thought of std::ostringstream! Any advice on how to implement such approach ?

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  • dynamic inheritance without touching classes

    - by Jasper
    I feel like the answer to this question is really simple, but I really am having trouble finding it. So here goes: Suppose you have the following classes: class Base; class Child : public Base; class Displayer { public: Displayer(Base* element); Displayer(Child* element); } Additionally, I have a Base* object which might point to either an instance of the class Base or an instance of the class Child. Now I want to create a Displayer based on the element pointed to by object, however, I want to pick the right version of the constructor. As I currently have it, this would accomplish just that (I am being a bit fuzzy with my C++ here, but I think this the clearest way) object->createDisplayer(); virtual void Base::createDisplayer() { new Displayer(this); } virtual void Child::createDisplayer() { new Displayer(this); } This works, however, there is a problem with this: Base and Child are part of the application system, while Displayer is part of the GUI system. I want to build the GUI system independently of the Application system, so that it is easy to replace the GUI. This means that Base and Child should not know about Displayer. However, I do not know how I can achieve this without letting the Application classes know about the GUI. Am I missing something very obvious or am I trying something that is not possible?

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  • How to get TextWidth of string (without Canvas)?

    - by lyborko
    Hi, I would like to get text width of a string before an application starts. Everything works fine untill Application.MainForm canvas present. The problem is, when I try dynamicaly create TOrdinarium in the OnCreate event of the app. main form, "Canvas does not allow drawing" error occures. (Application.MainForm is nil....). I tried several ways to create Canvas dynamicaly (one of them is written below), but it can not measure text sizes without being attached to parented control. Is there way how to make it work somehow? Thanx I tried this: TOrdinarium = class (TCustomControl) private function GetVirtualWidth:integer; end; constructor TOrdinarium.Create(AOwner:TComponent); begin inherited; Width:=GetVirtualWidth; end; function TOrdinarium.GetVirtualWidth:integer; var ACanvas : TControlCanvas; begin ACanvas := TControlCanvas.Create; TControlCanvas(ACanvas).Control := Application.MainForm; ACanvas.Font.Assign(Font); result:=ACanvas.TextWidth('0'); ACanvas.Free; end;

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  • How do I access abstract private data from derived class without friend or 'getter' functions in C++?

    - by John
    So, I am caught up in a dilemma right now. How am I suppose to access a pure abstract base class private member variable from a derived class? I have heard from a friend that it is possible to access it through the base constructor, but he didn't explain. How is it possible? There are some inherited classes from base class. Is there any way to gain access to the private variables ? class Base_button { private: bool is_vis; Rect rButton; public: // Constructors Base_button(); Base_button( const Point &corner, double height, double width ); // Destructor virtual ~ Base_button(); // Accessors virtual void draw() const = 0; bool clicked( const Point &click ) const; bool is_visible() const; // Mutators virtual void show(); virtual void hide(); void move( const Point &loc ); }; class Button : public Base_button { private: Message mButton; public: // Constructors Button(); Button( const Point &corner, const string &label ); // Acessors virtual void draw() const; // Mutators virtual void show(); virtual void hide(); }; I want to be able access Rect and bool in the base class from the subclass

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  • Generics in a bidirectional association

    - by Verhoevenv
    Let's say I have two classes A and B, with B a subtype of A. This is only part of a richer type hierarchy, obviously, but I don't think that's relevant. Assume A is the root of the hierarchy. There is a collection class C that keeps track of a list of A's. However, I want to make C generic, so that it is possible to make an instance that only keeps B's and won't accept A's. class A(val c: C[A]) { c.addEntry(this) } class B(c: C[A]) extends A(c) class C[T <: A]{ val entries = new ArrayBuffer[T]() def addEntry(e: T) { entries += e } } object Generic { def main(args : Array[String]) { val c = new C[B]() new B(c) } } The code above obviously give the error 'type mismatch: found C[B], required C[A]' on the new B(c) line. I'm not sure how this can be fixed. It's not possible to make C covariant in T (like C[+T <: A]) because the ArrayBuffer is non-variantly typed in T. It's not possible to make the constructor of B require a C[B] because C can't be covariant. Am I barking up the wrong tree here? I'm a complete Scala newbie, so any ideas and tips might be helpful. Thank you! EDIT: Basically, what I'd like to have is that the compiler accepts both val c = new C[B]() new B(c) and val c = new C[A]() new B(c) but would reject val c = new C[B]() new A(c) It's probably possible to relax the typing of the ArrayBuffer in C to be A instead of T, and thus in the addEntry method as well, if that helps.

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  • static member specialization of templated child class and templated base class

    - by b3nj1
    I'm trying to have a templated class (here C) that inherits from another templated class (here A) and perform static member specialization (of int var here), but I cant get the right syntax to do so (if it's possible #include <iostream> template<typename derived> class A { public: static int var; }; //This one works fine class B :public A<B> { public: B() { std::cout << var << std::endl; } }; template<> int A<B>::var = 9; //This one doesn't works template<typename type> class C :public A<C<type> > { public: C() { std::cout << var << std::endl; } }; //template<> template<typename type> int A<C<type> >::a = 10; int main() { B b; C<int> c; return 0; } I put an example that works with a non templated class (here B) and i can get the static member specialization of var, but for C that just doesn't work. Here is what gcc tells me : test.cpp: In constructor ‘C<type>::C()’: test.cpp:29:26: error: ‘var’ was not declared in this scope test.cpp: At global scope: test.cpp:34:18: error: template definition of non-template ‘int A<C<type> >::a’ I'm using gcc version 4.6.3, thanks for any help

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  • Android ProgressDialog inside another dialog

    - by La bla bla
    I'm working on a game using AndEngine, and I need to show the users the list of his Facebook friends. I've created my custom Adatper and after the loading finishes everything works great. I have a problem with the loading it self. The ListView is inside a custom dialog, since I don't really know how to create one using AndEngine, So inside this dialog, I'm running an AsyncTask to fetch the friends' info, in that AsyncTask I'm have a ProgressDialog. The problem is, the ProgressDialog shows up behind the dialog that contains the to-be list (which while loading, is just the title). I can see the ProgressDialog "peeking" behind that dialog.. Any Ideas? Here's some code: FriendsDialog.java private ProgressDialog dialog; //Constructor of the AsyncTask public FriendsLoader(Context context) { dialog = new ProgressDialog(context); dialog.setMessage("Please wait..\nLoading Friends List."); } @Override protected void onPreExecute() { dialog.requestWindowFeature(Window.FEATURE_NO_TITLE); LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); dialog.setView(inflater.inflate(R.layout.loading, null)); dialog.setMessage("Please wait..\nLoading friends."); dialog.show(); } @Override protected void onPostExecute(ArrayList<HashMap<String, Object>> data) { if (dialog.isShowing()) { dialog.dismiss(); } MyAdapter myAdapter = new MyAdapter(context, data); listView = (ListView) findViewById(R.id.list); listView.setAdapter(myAdapter); listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> myAdapter, View myView, int myItemInt, long mylng) { String id = (String) listView.getItemAtPosition(myItemInt); listener.onUserSelected(id); dismiss(); } }); }

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  • Porting Symbian C++ to Android NDK

    - by Donal Rafferty
    I've been given some Symbian C++ code to port over for use with the Android NDK. The code has lots of Symbian specific code in it and I have very little experience of C++ so its not going very well. The main thing that is slowing me down is trying to figure out the alternatives to use in normal C++ for the Symbian specific code. At the minute the compiler is throwing out all sorts of errors for unrecognised types. From my recent research these are the types that I believe are Symbian specific: TInt, TBool, TDesc8, RSocket, TInetAddress, TBuf, HBufc, RPointerArray Changing TInt and TBool to int and bool respectively works in the compiler but I am unsure what to use for the other types? Can anyone help me out with them? Especially TDesc, TBuf, HBuf. Also Symbian has a two phase contructor using NewL and NewLc But would changing this to a normal C++ constructor be ok? Finally Symbian uses the clean up stack to help eliminate memory leaks I believe, would removing the clean up stack code be acceptable, I presume it should be replaced with try/catch statements?

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  • Echoing variable construct instead of content

    - by danp
    I'm merging two different versions of a translations array. The more recent version has a lot of changes, over several thousand lines of code. To do this, I loaded and evaluated the new file (which uses the same structure and key names), then loaded and evaluated the older version, overwriting the new untranslated values in the array with the values we already have translated. So far so good! However, I want to be able to echo out the constructor for this new merged array so I can cut and paste it into the new translation file, and have job done (apart from completing the rest of the translations..). The code looks like this (lots of different keys, not just index): $lang["index"]["chart1_label1"] = "Subscribed"; $lang["index"]["chart1_label2"] = "Unsubscribed"; And the old.. $lang["index"]["chart1_label1"] = "Subscrito"; $lang["index"]["chart1_label2"] = "Não subscrito"; After loading the two files, I end up with a merged $lang array, which I then want to echo out in the same form, so it can be used by the project. However, when I do something like this.. foreach ($lang as $key => $value) { if (is_array($value)) { foreach ($value as $key2 => $value2) { echo "$lang['".$key."']"; // ... etc etc } } } ..obviously I get "ArrayIndex" etc etc instead of "$lang". How to echo out $lang without it being evaluated..? Once this is working, can add in the rest of the brackets etc (I realise they are missing), but just want to make this part work first. If there's a better way to do this, all ears too! Thanks.

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  • Complicated .NET factory design

    - by Tom W
    Hello SO; I'm planning to ask a fairly elaborate question that is also something of a musing here, so bear with me... I'm trying to design a factory implementation for a simulation application. The simulation will consist of different sorts of entities i.e. it is not a homogenous simulation in any respect. As a result, there will be numerous very different concrete implementations and only the very general properties will be abstracted at the top level. What I'd like to be able to do is create new simulation entities by calling a method on the model with a series of named arguments representing the parameters of the entity, and have the model infer what type of object is being described by the inbound parameters (from the names of the parameters and potentially the sequence they occur in) and call a factory method on the appropriate derived class. For example, if I pass the model a pair of parameters (Param1=5000, Param2="Bacon") I would like it to infer that the names Param1 and Param2 'belong' to the class "Blob1" and call a shared function "getBlob1" with named parameters Param1:=5000, Param2:="Bacon" whereas if I pass the model (Param1=5000, Param3=50) it would call a similar factory method for Blob2; because Param1 and Param3 in that order 'belong' to Blob2. I foresee several issues to resolve: Whether or not I can reflect on the available types with string parameter names and how to do this if it's possible Whether or not there's a neat way of doing the appropriate constructor inference from the combinatoric properties of the argument list or whether I'm going to have to bodge something to do it 'by hand'. If possible I'd like the model class to be able to accept parameters as parameters rather than as some collection of keys and values, which would require the model to expose a large number of parametrised methods at runtime without me having to code them explicitly - presumably one for every factory method available in the relevant namespace. What I'm really asking is how you'd go about implementing such a system, rather than whether or not it's fundamentally possible. I don't have the foresight or experience with .NET reflection to be able to figure out a way by myself. Hopefully this will prove an informative discussion.

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  • How can I theme custom form(drupal 6.x)

    - by Andrew
    DRUPAL 6.X I have this custom form constructor inside my custom module which is invoke through ajax request. I’m attempting to theme this form with the template file reside in my theme directory. For that matter, I’ve registered my theme inside template.php file which reside in my theme folder. Here’s how this file looks – function my_theme() { return array( 'searchdb' => array( 'arguments' => array('form' => NULL), 'template' => 'searchform', ) ); } And the following is the excerpt of module code – function test_menu() { $my_form['searchdb'] = array( 'title' => 'Search db', 'page callback' => 'get_form', 'page arguments' => array(0), 'access arguments' => array('access content'), 'type' => MENU_CALLBACK, ); return $my_form; } function get_form($formtype){ switch($formtype){ case 'searchdb' : echo drupal_get_form('searchdb'); break; } } function searchdb(){ $form['customer_name'] = array( '#type' => 'textfield', '#title' => t('Customer Name'), '#size' => 50, '#attributes' => array('class' => 'name-textbox'), ); return $form; } As you can imagine, this is not working at all. Just to test if my theme is even registered, I’ve also tested with theme function but, it’s not called. I've checked template file name and form-id(through the outputted html source) and everything seems ok. I would be glad if anyone could point me to the right direction.

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  • What are the drawbacks of this Classing format?

    - by Keysle
    This is a 3 layer example of my classing format function __(_){return _.constructor} //class var _ = ( CLASS = function(){ this.variable = 0; this.sub = new CLASS.SUBCLASS(); }).prototype; _.func = function(){ alert('lvl'+this.variable); this.sub.func(); } _.divePeak = function(){ alert('lvl'+this.variable); this.sub.variable += 5; } //sub class _ = ( __(_).SUBCLASS = function(){ this.variable = 1; this.sub = new CLASS.SUBCLASS.DEEPCLASS(); }).prototype; _.func = function(){ alert('lvl'+this.variable); this.sub.func(); } //deep class _ = ( __(_).DEEPCLASS = function(){ this.variable = 2; }).prototype; _.func = function(){ alert('lvl'+this.variable); } Before you blow a gasket, let me explain myself. The purpose behind the underscores is to accelerate the time needed to specify functions for a class and also specify sub classes of a class. To me it's easier to read. I KNOW, this does interfere with underscore.js if you intend to use it in your classes. I'm sure _.js can be easily switched over to another $ymbol though ... oh wait, But I digress. Why have classes within a class? because solar.system() and social.system() mean two totally different things but it's convenient to use the same name. Why user underscores to manage the definition of the class? because "Solar.System.prototype" took me about 2 seconds to type out and 2 typos to correct. It also keeps all function names for all classes in the same column of texts, which is nice for legibility. All I'm doing is presenting my reasoning behind this method and why I came up with it. I'm 3 days into learning OO JS and I am very willing to accept that I might have messed up.

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  • Where should I put validation code?

    - by D Lawson
    I'm creating interfaces and abstract classes that represent a messaging framework for short text-based messages like SMS, email, twitter, xml, etc.. and I was wondering where I should put the message validation code. The thing is that I am only writing the superclasses and interfaces, so I'm not putting the actual implementation in, I'll just put the hooks in that allow others to validate the content of the messages. The way I see it, I could do it several ways: in the abstract superclass "Message", have an abstract method 'isValid'. A variation on this would be to have isValid be called when the Message constructor is called, throwing a MalformedMessageException if the message is formatted incorrectly. in the transport layer, immediately before sending, validate the message. I would have a send(Message) method that calls an isValid(Message) method immediately before it sends. have a singleton message validator with a static method isValid(Message) that is called at some point. I'm sure there are other options that I'm missing. Currently, I'm leaning towards the first one, but it doesn't feel right to me to have validation code in what should be a domain object.

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  • Need advice on C++ coding pattern

    - by Kotti
    Hi! I have a working prototype of a game engine and right now I'm doing some refactoring. What I'm asking for is your opinion on usage of the following C++ coding patterns. I have implemented some trivial algorithms for collision detection and they are implemented the following way: Not shown here - class constructor is made private and using algorithms looks like Algorithm::HandleInnerCollision(...) struct Algorithm { // Private routines static bool is_inside(Point& p, Object& object) { // (...) } public: /** * Handle collision where the moving object should be always * located inside the static object * * @param MovingObject & mobject * @param const StaticObject & sobject * @return void * @see */ static void HandleInnerCollision(MovingObject& mobject, const StaticObject& sobject) { // (...) } So, my question is - somebody advised me to do it "the C++" way - so that all functions are wrapped in a namespace, but not in a class. Is there some good way to preserve privating if I will wrap them into a namespace as adviced? What I want to have is a simple interface and ability to call functions as Algorithm::HandleInnerCollision(...) while not polluting the namespace with other functions such as is_inside(...) Of, if you can advise any alternative design pattern for such kind of logics, I would really appreciate that...

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  • WPF Binding Path=/ not working?

    - by Mark
    I've set up my DataContext like this: <Window.DataContext> <c:DownloadManager /> </Window.DataContext> Where DownloadManager is Enumerable<DownloadItem>. Then I set my DataGrid like this: <DataGrid Name="dataGrid1" ItemsSource="{Binding Path=/}" ... So that it should list all the DownloadItems, right? So I should be able to set my columns like: <DataGridTextColumn Binding="{Binding Path=Uri, Mode=OneWay}" Where Uri is a property of the DownloadItem. But it doesn't seem to like this. In the visual property editor, it doesn't recognize Uri is a valid property, so I'm guessing I'm doing something wrong. It was working before, when I had the data grid binding to Values, but then I took that enumerable out of the DownloadManager and made itself enumerable. How do I fix this? PS: By "doesn't work" I mean it doesn't list any items. I've added some to the constructor of the DM, so it shouldn't be empty.

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  • efficient thread-safe singleton in C++

    - by user168715
    The usual pattern for a singleton class is something like static Foo &getInst() { static Foo *inst = NULL; if(inst == NULL) inst = new Foo(...); return *inst; } However, it's my understanding that this solution is not thread-safe, since 1) Foo's constructor might be called more than once (which may or may not matter) and 2) inst may not be fully constructed before it is returned to a different thread. One solution is to wrap a mutex around the whole method, but then I'm paying for synchronization overhead long after I actually need it. An alternative is something like static Foo &getInst() { static Foo *inst = NULL; if(inst == NULL) { pthread_mutex_lock(&mutex); if(inst == NULL) inst = new Foo(...); pthread_mutex_unlock(&mutex); } return *inst; } Is this the right way to do it, or are there any pitfalls I should be aware of? For instance, are there any static initialization order problems that might occur, i.e. is inst always guaranteed to be NULL the first time getInst is called?

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  • Python NameError when attempting to use a user-defined class

    - by Michael Herold
    I'm getting a weird instance of a NameError when attempting to use a class I wrote. In a directory, I have the following file structure: dir/ ReutersParser.py test.py reut-xxx.sgm Where my custom class is defined in ReutersParser.py and I have a test script defined in test.py. The ReutersParser looks something like this: from sgmllib import SGMLParser class ReutersParser(SGMLParser): def __init__(self, verbose=0): SGMLParser.__init__(self, verbose) ... rest of parser if __name__ == '__main__': f = open('reut2-short.sgm') s = f.read() p = ReutersParser() p.parse(s) It's a parser to deal with SGML files of Reuters articles. The test works perfectly. Anyway, I'm going to use it in test.py, which looks like this: from ReutersParser import ReutersParser def main(): parser = ReutersParser() if __name__ == '__main__': main() When it gets to that parser line, I'm getting this error: Traceback (most recent call last): File "D:\Projects\Reuters\test.py", line 34, in <module> main() File "D:\Projects\Reuters\test.py", line 19, in main parser = ReutersParser() File "D:\Projects\Reuters\ReutersParser.py", line 38, in __init__ SGMLParser.__init__(self, verbose) NameError: global name 'sgmllib' is not defined For some reason, when I try to use my ReutersParser in test.py, it throws an error that says it cannot find sgmllib, which is a built-in module. I'm at my wits' end trying to figure out why the import won't work. What's causing this NameError? I've tried importing sgmllib in my test.py and that works, so I don't understand why it can't find it when trying to run the constructor for my ReutersParser.

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  • Working with Java using methods and arrays [closed]

    - by jordan
    Hi i'm a newb at java and for one of my labs I have to create a instant messenger client with these requirements: add buddyList instance variable add IMClient constructor to create ArrayList addBuddy method removeBuddy method findBuddy method printBuddyList method what's the best way to go about this? so far I have this: public class IMClient { private String userId; // User id private String password; // Password private int status; // Status code for user: 1 - Online, 2 - Off-line, 3 - Away public IMClient(String userId, String password, int status) { super(); this.userId = userId; this.password = password; this.status = status; } // Returns true if password as a parameter matches password instance variable. public boolean checkPassword(String password) { return this.password.equals(password); } public String toString() { StringBuffer buf = new StringBuffer(100); buf.append(" User id: "); buf.append(userId); buf.append(" Password: "); buf.append(password); buf.append(" Status: "); buf.append(status); return buf.toString(); } public String getUserId() { return userId; } public void setUserId(String userId) { this.userId = userId; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public int getStatus() { return status; } public void setStatus(int status) { this.status = status; } public static void main(String[] args) { } }

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  • XmlSerializer construction with same named extra types

    - by NoizWaves
    Hey, I am hitting trouble constructing an XmlSerializer where the extra types contains types with the same Name (but unique Fullname). Below is an example that illustrated my scenario. Type definitions in external assembly I cannot manipulate: public static class Wheel { public enum Status { Stopped, Spinning } } public static class Engine { public enum Status { Idle, Full } } Class I have written and have control over: public class Car { public Wheel.Status WheelStatus; public Engine.Status EngineStatus; public static string Serialize(Car car) { var xs = new XmlSerializer(typeof(Car), new[] {typeof(Wheel.Status),typeof(Engine.Status)}); var output = new StringBuilder(); using (var sw = new StringWriter(output)) xs.Serialize(sw, car); return output.ToString(); } } The XmlSerializer constructor throws a System.InvalidOperationException with Message "There was an error reflecting type 'Engine.Status'" This exception has an InnerException of type System.InvalidOperationException and with Message "Types 'Wheel.Status' and 'Engine.Status' both use the XML type name, 'Status', from namespace ''. Use XML attributes to specify a unique XML name and/or namespace for the type." Given that I am unable to alter the enum types, how can I construct an XmlSerializer that will serialize Car successfully?

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