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  • How can you transform a set of numbers into mostly whole ones?

    - by Alice
    Small amount of background: I am working on a converter that bridges between a map maker (Tiled) that outputs in XML, and an engine (Angel2D) that inputs lua tables. Most of this is straight forward However, Tiled outputs in pixel offsets (integers of absolute values), while Angel2D inputs OpenGL units (floats of relative values); a conversion factor between these two is needed (for example, 32px = 1gu). Since OpenGL units are abstract, and the camera can zoom in or out if the objects are too small or big, the actual conversion factor isn't important; I could use a random number, and the user would merely have to zoom in or out. But it would be best if the conversion factor was selected such that most numbers outputted were small and whole (or fractions of small whole numbers), because that makes it easier to work with (and the whole point of the OpenGL units is that they are easy to work with). How would I find such a conversion factor reliably? My first attempt was to use the smallest number given; this resulted in no fractions below 1, but often lead to lots of decimal places where the factors didn't line up. Then I tried the mode of the sequence, which lead to the largest number of 1's possible, but often lead to very long floats for background images. My current approach gets the GCD of the whole sequence, which, when it works, works great, but can easily be thrown off course by a single bad apple. Note that while I could easily just pass the numbers I am given along, or pick some fixed factor, or use one of the conversions I specified above, I am looking for a method to reliably scale this list of integers to small, whole numbers or simple fractions, because this would most likely be unsurprising to the end user; this is not a one off conversion. The end users tend to use 1.0 as their "base" for manipulations (because it's simple and obvious), so it would make more sense for the sizes of entities to cluster around this.

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  • adding an uncertain number of fields using javascript

    - by user306472
    I'm new to javascript and a novice programmer, so this might be a really easy question to answer. I would like to loop over the values of x number of fields and add them up to display the sum in a final field. I can perform this function if I explicitly call each field, but I want to abstract this so I can deal with a flexible number of fields. Here's example code I've come up with (that's not working for me). Where am I going wrong? <html> <head> <script type="text/javascript"> function startAdd(){ interval = setInterval("addfields()",1); } function addfields(){ a = document.addition.total.value; b = getElementByTagName("sum").value; for (i=0; i<=b.length; i++){ a+=i; } return a; } function stopAdd(){ clearInterval(interval); } </script> </head> <body> <form name="addition"> <input type="text" name="sum" onFocus="startAdd();" onBlur="stopAdd;"> + <input type="text" name="sum" onFocus="startAdd();" onBlur="stopAdd;"> = <input type="text" name ="total"> </form> </body> </html>

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  • NHibernate unintential lazy property loading

    - by chiccodoro
    I introduced a mapping for a business object which has (among others) a property called "Name": public class Foo : BusinessObjectBase { ... public virtual string Name { get; set; } } For some reason, when I fetch "Foo" objects, NHibernate seems to apply lazy property loading (for simple properties, not associations): The following code piece generates n+1 SQL statements, whereof the first only fetches the ids, and the remaining n fetch the Name for each record: ISession session = ...IQuery query = session.CreateQuery(queryString); ITransaction tx = session.BeginTransaction(); List<Foo> result = new List<Foo>(); foreach (Foo foo in query.Enumerable()) { result.Add(foo); } tx.Commit(); session.Close(); produces: NHibernate: select foo0_.FOO_ID as col_0_0_ from V1_FOO foo0_ NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 81 NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 36470 NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 36473 Similarly, the following code leads to a LazyLoadingException after session is closed: ISession session = ... ITransaction tx = session.BeginTransaction(); Foo result = session.Load<Foo>(id); tx.Commit(); session.Close(); Console.WriteLine(result.Name); Following this post, "lazy properties ... is rarely an important feature to enable ... (and) in Hibernate 3, is disabled by default." So what am I doing wrong? I managed to work around the LazyLoadingException by doing a NHibernateUtil.Initialize(foo) but the even worse part are the n+1 sql statements which bring my application to its knees. This is how the mapping looks like: <class name="Foo" table="V1_FOO"> ... <property name="Name" column="NAME"/> </class> BTW: The abstract "BusinessObjectBase" base class encapsulates the ID property which serves as the internal identifier.

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  • What OOP pattern to use when only adding new methods, not data?

    - by Jonathon Reinhart
    Hello eveyone... In my app, I have deal with several different "parameters", which derive from IParameter interface, and also ParamBase abstract base class. I currently have two different parameter types, call them FooParameter and BarParameter, which both derive from ParamBase. Obviously, I can treat them both as IParameters when I need to deal with them generically, or detect their specific type when I need to handle their specific functionality. My question lies in specific FooParameters. I currently have a few specific ones with their own classes which derive from FooParameter, we'll call them FP12, FP13, FP14, etc. These all have certain characteristics, which make me treat them differently in the UI. (Most have names associated with the individual bits, or ranges of bits). Note that these specific, derived FP's have no additional data associated with them, only properties (which refer to the same data in different ways) or methods. Now, I'd like to keep all of these parameters in a Dictionary<String, IParameter> for easy generic access. The problem is, if I want to refer to a specific one with the special GUI functions, I can't write: FP12 fp12 = (FP12)paramList["FP12"] because you can't downcast to a derived type (rightfully so). But in my case, I didn't add any data, so the cast would theoretically work. What type of programming model should I be using instead? Thanks!

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  • Auto increment with a Unit Of Work

    - by Derick
    Context I'm building a persistence layer to abstract different types of databases that I'll be needing. On the relational part I have mySQL, Oracle and PostgreSQL. Let's take the following simplified MySQL tables: CREATE TABLE Contact ( ID varchar(15), NAME varchar(30) ); CREATE TABLE Address ( ID varchar(15), CONTACT_ID varchar(15), NAME varchar(50) ); I use code to generate system specific alpha numeric unique ID's fitting 15 chars in this case. Thus, if I insert a Contact record with it's Addresses I have my generated Contact.ID and Address.CONTACT_IDs before committing. I've created a Unit of Work (amongst others) as per Martin Fowler's patterns to add transaction support. I'm using a key based Identity Map in the UoW to track the changed records in memory. It works like a charm for the scenario above, all pretty standard stuff so far. The question scenario comes in when I have a database that is not under my control and the ID fields are auto-increment (or in Oracle sequences). In this case I do not have the db generated Contact.ID beforehand, so when I create my Address I do not have a value for Address.CONTACT_ID. The transaction has not been started on the DB session since all is kept in the Identity Map in memory. Question: What is a good approach to address this? (Avoiding unnecessary db round trips) Some ideas: Retrieve the last ID: I can do a call to the database to retrieve the last Id like: SELECT Auto_increment FROM information_schema.tables WHERE table_name='Contact'; But this is MySQL specific and probably something similar can be done for the other databases. If do this then would need to do the 1st insert, get the ID and then update the children (Address.CONTACT_IDs) – all in the current transaction context.

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  • How can I implement CRUD operations in a base class for an entity framework app?

    - by hminaya
    I'm working a simple EF/MVC app and I'm trying to implement some Repositories to handle my entities. I've set up a BaseObject Class and a IBaseRepository Interface to handle the most basic operations so I don't have to repeat myself each time: public abstract class BaseObject<T> { public XA.Model.Entities.XAEntities db; public BaseObject() { db = new Entities.XAEntities(); } public BaseObject(Entities.XAEntities cont) { db = cont; } public void Delete(T entity) { db.DeleteObject(entity); db.SaveChanges(); } public void Update(T entity) { db.AcceptAllChanges(); db.SaveChanges(); } } public interface IBaseRepository<T> { void Add(T entity); T GetById(int id); IQueryable<T> GetAll(); } But then I find myself having to implement 3 basic methods in every Repository ( Add, GetById & GetAll): public class AgencyRepository : Framework.BaseObject<Agency>, Framework.IBaseRepository<Agency> { public void Add(Agency entity) { db.Companies.AddObject(entity); db.SaveChanges(); } public Agency GetById(int id) { return db.Companies.OfType<Agency>().FirstOrDefault(x => x.Id == id); } public IQueryable<Agency> GetAll() { var agn = from a in db.Companies.OfType<Agency>() select a; return agn; } } How can I get these into my BaseObject Class so I won't run in conflict with DRY.

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  • Javascript CS-PRNG - 64-bit random

    - by Jack
    Hi, I need to generate a cryptographically secure 64-bit unsigned random integer in Javascript. The first problem is that Javascript only allows 64-bit signed integers, so 9223372036854775808 is the biggest supported integer without going into floating point use I think? To fix this I can use a big number library, no problem. My Method: var randNum = SHA256( randBigInt(128, 0) ) % 2^64; Where SHA256() is a secure hash function and randBigInt() is defined below as a non-crypto PRNG, im giving it a 128bit seed so brute force shouldn't be a problem. randBigInt(n,s) //return an n-bit random BigInt (n>=1). If s=1, then the most significant of those n bits is set to 1. Is this a secure method to generate a cryptographically secure 64-bit random int? And importantly does taking the 2^64 mod guarantee 100% I have a 64-bit number? An abstract example, say this number is prime (it isn't i know), I will use it in the Galois Field [2^p], where p must be 64bits so that every possible 1-63bit number is a field element. In this query, my random int must be larger than any 63-bit number. And Im not sure im correct in taking the 2^64 mod of a 256bit hash output. Thanks (hope that makes sense)

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  • How to specialize a type parameterized argument to multiple different types for in Scala?

    - by jmount
    I need a back-check (please). In an article ( http://www.win-vector.com/blog/2010/06/automatic-differentiation-with-scala/ ) I just wrote I stated that it is my belief in Scala that you can not specify a function that takes an argument that is itself a function with an unbound type parameter. What I mean is you can write: def g(f:Array[Double]=>Double,Array[Double]):Double but you can not write something like: def g(f[Y]:Array[Y]=>Double,Array[Double]):Double because Y is not known. The intended use is that inside g() I will specialize fY to multiple different types at different times. You can write: def g[Y](f:Array[Y]=>Double,Array[Double]):Double but then f() is of a single type per call to g() (which is exactly what we do not want). However, you can get all of the equivalent functionality by using a trait extension instead insisting on passing around a function. What I advocated in my article was: 1) Creating a trait that imitates the structure of Scala's Function1 trait. Something like: abstract trait VectorFN { def apply[Y](x:Array[Y]):Y } 2) declaring def g(f:VectorFN,Double):Double (using the trait is the type). This works (people here on StackOverflow helped me find it, and I am happy with it)- but am I mis-representing Scala by missing an even better solution?

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  • Applying the Decorator Pattern to Forms

    - by devoured elysium
    I am trying to apply the Decorator Design Pattern to the following situation: I have 3 different kind of forms: Green, Yellow, Red. Now, each of those forms can have different set of attributes. They can have a minimize box disabled, a maximized box disabled and they can be always on top. I tried to model this the following way: Form <---------------------------------------FormDecorator /\ /\ |---------|-----------| |----------------------|-----------------| GreenForm YellowForm RedForm MinimizeButtonDisabled MaximizedButtonDisabled AlwaysOnTop Here is my GreenForm code: public class GreenForm : Form { public GreenForm() { this.BackColor = Color.GreenYellow; } public override sealed Color BackColor { get { return base.BackColor; } set { base.BackColor = value; } } } FormDecorator: public abstract class FormDecorator : Form { private Form _decoratorForm; protected FormDecorator(Form decoratorForm) { this._decoratorForm = decoratorForm; } } and finally NoMaximizeDecorator: public class NoMaximizeDecorator : FormDecorator { public NoMaximizeDecorator(Form decoratorForm) : base(decoratorForm) { this.MaximizeBox = false; } } So here is the running code: static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(CreateForm()); } static Form CreateForm() { Form form = new GreenForm(); form = new NoMaximizeDecorator(form); form = new NoMinimizeDecorator(form); return form; } The problem is that I get a form that isn't green and that still allows me to maximize it. It is only taking in consideration the NoMinimizeDecorator form. I do comprehend why this happens but I'm having trouble understanding how to make this work with this Pattern. I know probably there are better ways of achieving what I want. I made this example as an attempt to apply the Decorator Pattern to something. Maybe this wasn't the best pattern I could have used(if one, at all) to this kind of scenario. Is there any other pattern more suitable than the Decorator to accomplish this? Am I doing something wrong when trying to implement the Decorator Pattern? Thanks

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  • Which is the better C# class design for dealing with read+write versus readonly

    - by DanM
    I'm contemplating two different class designs for handling a situation where some repositories are read-only while others are read-write. (I don't foresee any need to a write-only repository.) Class Design 1 -- provide all functionality in a base class, then expose applicable functionality publicly in sub classes public abstract class RepositoryBase { protected virtual void SelectBase() { // implementation... } protected virtual void InsertBase() { // implementation... } protected virtual void UpdateBase() { // implementation... } protected virtual void DeleteBase() { // implementation... } } public class ReadOnlyRepository : RepositoryBase { public void Select() { SelectBase(); } } public class ReadWriteRepository : RepositoryBase { public void Select() { SelectBase(); } public void Insert() { InsertBase(); } public void Update() { UpdateBase(); } public void Delete() { DeleteBase(); } } Class Design 2 - read-write class inherits from read-only class public class ReadOnlyRepository { public void Select() { // implementation... } } public class ReadWriteRepository : ReadOnlyRepository { public void Insert() { // implementation... } public void Update() { // implementation... } public void Delete() { // implementation... } } Is one of these designs clearly stronger than the other? If so, which one and why? P.S. If this sounds like a homework question, it's not, but feel free to use it as one if you want :)

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  • iPhone: Calling dealloc on parentViewController causes an exception

    - by arielcamus
    Hi, I'm dealing with viewDidUnload and dealloc methods and I've founded a problem when calling [super dealloc]; in parent view controller. I have a lot of view controllers with custom code which I have putted outside on a parent view controller. So, when defining my view controllers I set a reference to the super class: @interface LoginViewController : AbstractViewController Then, at the dealloc method I call the AbstractViewController dealloc method: //(Login View Controller code) - (void)dealloc { [user release]; [passwd release]; [super dealloc]; } [super dealloc] execute the following code: //(Abstract View Controller code) - (void)dealloc { [dbUtils release]; [loadingView release]; [super dealloc]; } If I simulate a memory warning on iPhone Simulator, the following exception is thrown: 2010-03-03 11:27:45.805 MyApp[71563:40b] Received simulated memory warning. 2010-03-03 11:27:45.808 MyApp[71563:40b] *** -[LoginViewController isViewLoaded]: message sent to deallocated instance 0x13b51b0 kill quit However, if I comment the [super dealloc] line in AbstractViewController the exception is not thrown and my app still running. Thank you for your help once again!

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  • using STI and ActiveRecordBase<> with full FindAll

    - by oillio
    Is it possible to use generic support with single table inheritance, and still be able to FindAll of the base class? As a bonus question, will I be able to use ActiveRecordLinqBase< as well? I do love those queries. More detail: Say I have the following classes defined: public interface ICompany { int ID { get; set; } string Name { get; set; } } [ActiveRecord("companies", DiscriminatorColumn="type", DiscriminatorType="String", DiscriminatorValue="NA")] public abstract class Company<T> : ActiveRecordBase<T>, ICompany { [PrimaryKey] private int Id { get; set; } [Property] public String Name { get; set; } } [ActiveRecord(DiscriminatorValue="firm")] public class Firm : Company<Firm> { [Property] public string Description { get; set; } } [ActiveRecord(DiscriminatorValue="client")] public class Client : Company<Client> { [Property] public int ChargeRate { get; set; } } This works fine for most cases. I can do things like: var x = Client.FindAll(); But sometimes I want all of the companies. If I was not using generics I could do: var x = (Company[]) FindAll(Company); Client a = (Client)x[0]; Firm b = (Firm)x[1]; Is there a way to write a FindAll that returns an array of ICompany's that can then be typecast into their respective types? Something like: var x = (ICompany[]) FindAll(Company<ICompany>); Client a = (Client)x[0]; Or maybe I am going about implementing the generic support all wrong?

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  • Should a developer be a coauthor to a paper presented about the application they developed?

    - by ved
    In our organization, project teams come up with a need and funding and developers are given a basic scope and are allowed to develop the solution. There is a certain degree of implementation freedom given to the developers. They drive the solution to pilot and live deployment from its inception. If the solution is presented in a conference as a technical paper/white paper what is the protocol for the list of authors: because for the most part I see the project manager's and the dev team manager's names as authors but no mention of the actual developer. Is this correct? A lot of us developers feel pretty bummed to never see our names as the coauthors. Appreciate any pointers. Answers to the FOLLOW UP questions (1) in what field of study is the paper, and what are the standards of authorship for that field? The paper is for Flood Plain Management - there is nothing on the abstract guidelines, I have called the contact person listed for comment - waiting to hear. 2) was the paper literally about the software application as your question implies, or were the software issues incidental to the topic of the paper? The paper specifically deals with a GIS Application that is used in Coastal Engineering, yes the software is not incidental, but the meat of the paper and mentioned in the Title. 2

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  • Spawning a thread in python

    - by morpheous
    I have a series of 'tasks' that I would like to run in separate threads. The tasks are to be performed by separate modules. Each containing the business logic for processing their tasks. Given a tuple of tasks, I would like to be able to spawn a new thread for each module as follows. from foobar import alice, bob charles data = getWorkData() # these are enums (which I just found Python doesn't support natively) :( tasks = (alice, bob, charles) for task in tasks # Ok, just found out Python doesn't have a switch - @#$%! # yet another thing I'll need help with then ... switch case alice: #spawn thread here - how ? alice.spawnWorker(data) No prizes for guessing I am still thinking in C++. How can I write this in a Pythonic way using Pythonic 'enums' and 'switch'es, and be able to run a module in a new thread. Obviously, the modules will all have a class that is derived from a ABC (abstract base class) called Plugin. The spawnWorker() method will be declared on the Plugin interface and defined in the classes implemented in the various modules. Maybe, there is a better (i.e. Pythonic) way of doing all this?. I'd be interested in knowing

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  • .NET MissingMethodException occuring on one of thousands of end-user machines -- any insight?

    - by Yoooder
    This issue has me baffled, it's affecting a single user (to my knowledge) and hasn't been reproduced by us... The user is receiving a MissingMethodException, our trace file indicates it's occuring after we create a new instance of a component, when we're calling an Initialize/Setup method in preparation to have it do work (InitializeWorkerByArgument in the example) The Method specified by the error is an interface method, which a base class implements and classes derived from the base class can override as-needed The user has the latest release of our application All the provided code is shipped within a single assembly Here's a very distilled version of the component: class Widget : UserControl { public void DoSomething(string argument) { InitializeWorkerByArgument(argument); this.Worker.DoWork(); } private void InitializeWorkerByArgument(string argument) { switch (argument) { case "SomeArgument": this.Worker = new SomeWidgetWorker(); break; } // The issue I'm tracking down would have occured during "new SomeWidgetWorker()" // and would have resulted in a missing method exception stating that // method "DoWork" could not be found. this.Worker.DoWorkComplete += new EventHandler(Worker_DoWorkComplete); } private IWidgetWorker Worker { get; set; } void Worker_DoWorkComplete(object sender, EventArgs e) { MessageBox.Show("All done"); } } interface IWidgetWorker { void DoWork(); event EventHandler DoWorkComplete; } abstract class BaseWorker : IWidgetWorker { virtual public void DoWork() { System.Threading.Thread.Sleep(1000); RaiseDoWorkComplete(this, null); } internal void RaiseDoWorkComplete(object sender, EventArgs e) { if (DoWorkComplete != null) { DoWorkComplete(this, null); } } public event EventHandler DoWorkComplete; } class SomeWidgetWorker : BaseWorker { public override void DoWork() { System.Threading.Thread.Sleep(2000); RaiseDoWorkComplete(this, null); } }

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  • Most "thorough" distribution of points around a circle

    - by hippietrail
    This question is intended to both abstract and focus one approach to my problem expressed at "Find the most colourful image in a collection of images". Imagine we have a set of circles, each has a number of points around its circumference. We want to find a metric that gives a higher rating to a circle with points distributed evenly around the circle. Circles with some points scattered through the full 360° are better but circles with far greater numbers of points in one area compared to a smaller number in another area are less good. The number of points is not limited. Two or more points may coincide. Coincidental points are still relevant. A circle with one point at 0° and one point at 180° is better than a circle with 100 points at 0° and 1000 points at 180°. A circle with one point every degree around the circle is very good. A circle with a point every half degree around the circle is better. In my other (colour based question) it was suggested that standard deviation would be useful but with caveat. Is this a good suggestion and does it cope with the closeness of 359° to 1°?

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  • DBTransactions between stateless calls using GUIDs

    - by Marty Trenouth
    I'm looking to add transactional support to my DB engine and providing to Abstract Transaction Handling down to passing in Guids with the DB Action Command. The DB engine would run similar to: private static Database DB; public static Dictionary<Guid,DBTransaction> Transactions = new ...() public static void DoDBAction(string cmdstring,List<Parameter> parameters,Guid TransactionGuid) { DBCommand cmd = BuildCommand(cmdstring,parameters); if(Transactions.ContainsKey(TransactionGuid)) cmd.Transaction = Transactions[TransactionGuid]; DB.ExecuteScalar(cmd); } public static BuildCommand(string cmd, List<Parameter> parameters) { // Create DB command from EntLib Database and assign parameters } public static Guid BeginTransaction() { // creates new Transaction adding it to "Transactions" and opens a new connection } public static Guid Commit(Guid g) { // Commits Transaction and removes it from "Transactions" and closes connection } public static Guid Rollback(Guid g) { // Rolls back Transaction and removes it from "Transactions" and closes connection } The Calling system would run similar to: Guid g try { g = DBEngine.BeginTransaction() DBEngine.DoDBAction(cmdstring1, parameters,g) // do some other stuff DBEngine.DoDBAction(cmdstring2, parameters2,g) // sit here and wait for a response from other item DBEngine.DoDBAction(cmdstring3, parameters3,g) DBEngine.Commit(g) } catch(Exception){ DBEngine.Rollback(g);} Does this interfere with .NET connection pooling (other than a connection be accidently left open)? Will EntLib keep the connection open until the commit or rollback?

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  • android custom dialog imageButton onclicklistener

    - by Asaf Nevo
    this is my custom dialog class: package com.WhosAround.Dialogs; import com.WhosAround.AppVariables; import com.WhosAround.R; import com.WhosAround.AsyncTasks.LoadUserStatus; import com.WhosAround.Facebook.FacebookUser; import android.app.Dialog; import android.content.Context; import android.graphics.drawable.Drawable; import android.view.MotionEvent; import android.view.View; import android.widget.ImageButton; import android.widget.ImageView; import android.widget.TextView; public class MenuFriend extends Dialog{ private FacebookUser friend; private AppVariables app; public MenuFriend(Context context, FacebookUser friend) { super(context, android.R.style.Theme_Translucent_NoTitleBar); this.app = (AppVariables) context.getApplicationContext(); this.friend = friend; } public void setDialog(String userName, Drawable userProfilePicture) { setContentView(R.layout.menu_friend); setCancelable(true); setCanceledOnTouchOutside(true); TextView name = (TextView) findViewById(R.id.menu_user_name); TextView status = (TextView) findViewById(R.id.menu_user_status); ImageView profilePicture = (ImageView) findViewById(R.id.menu_profile_picture); ImageButton closeButton = (ImageButton) findViewById(R.id.menu_close); name.setText(userName); profilePicture.setImageDrawable(userProfilePicture); if (friend.getStatus() != null) status.setText(friend.getStatus()); else new LoadUserStatus(app, friend, status).execute(0); closeButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { dismiss(); } }) } } for some reason eclipse tells me the following errors on closeButton imageButton: The method setOnClickListener(View.OnClickListener) in the type View is not applicable for the arguments (new DialogInterface.OnClickListener(){}) The type new DialogInterface.OnClickListener(){} must implement the inherited abstract method DialogInterface.OnClickListener.onClick(DialogInterface, int) The method onClick(View) of type new DialogInterface.OnClickListener(){} must override or implement a supertype method why is that ?

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  • Refactoring code/consolidating functions (e.g. nested for-loop order)

    - by bmay2
    Just a little background: I'm making a program where a user inputs a skeleton text, two numbers (lower and upper limit), and a list of words. The outputs are a series of modifications on the skeleton text. Sample inputs: text = "Player # likes @." (replace # with inputted integers and @ with words in list) lower = 1 upper = 3 list = "apples, bananas, oranges" The user can choose to iterate over numbers first: Player 1 likes apples. Player 2 likes apples. Player 3 likes apples. Or words first: Player 1 likes apples. Player 1 likes bananas. Player 1 likes oranges. I chose to split these two methods of outputs by creating a different type of dictionary based on either number keys (integers inputted by the user) or word keys (from words in the inputted list) and then later iterating over the values in the dictionary. Here are the two types of dictionary creation: def numkey(dict): # {1: ['Player 1 likes apples', 'Player 1 likes...' ] } text, lower, upper, list = input_sort(dict) d = {} for num in range(lower,upper+1): l = [] for i in list: l.append(text.replace('#', str(num)).replace('@', i)) d[num] = l return d def wordkey(dict): # {'apples': ['Player 1 likes apples', 'Player 2 likes apples'..] } text, lower, upper, list = input_sort(dict) d = {} for i in list: l = [] for num in range(lower,upper+1): l.append(text.replace('#', str(num)).replace('@', i)) d[i] = l return d It's fine that I have two separate functions for creating different types of dictionaries but I see a lot of repetition between the two. Is there any way I could make one dictionary function and pass in different values to it that would change the order of the nested for loops to create the specific {key : value} pairs I'm looking for? I'm not sure how this would be done. Is there anything related to functional programming or other paradigms that might help with this? The question is a little abstract and more stylistic/design-oriented than anything.

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  • Serializing Configurations for a Dependency Injection / Inversion of Control

    - by Joshua Starner
    I've been researching Dependency Injection and Inversion of Control practices lately in an effort to improve the architecture of our application framework and I can't seem to find a good answer to this question. It's very likely that I have my terminology confused, mixed up, or that I'm just naive to the concept right now, so any links or clarification would be appreciated. Many examples of DI and IoC containers don't illustrate how the container will connect things together when you have a "library" of possible "plugins", or how to "serialize" a given configuration. (From what I've read about MEF, having multiple declarations of [Export] for the same type will not work if your object only requires 1 [Import]). Maybe that's a different pattern or I'm blinded by my current way of thinking. Here's some code for an example reference: public abstract class Engine { } public class FastEngine : Engine { } public class MediumEngine : Engine { } public class SlowEngine : Engine { } public class Car { public Car(Engine e) { engine = e; } private Engine engine; } This post talks about "Fine-grained context" where 2 instances of the same object need different implementations of the "Engine" class: http://stackoverflow.com/questions/2176833/ioc-resolve-vs-constructor-injection Is there a good framework that helps you configure or serialize a configuration to achieve something like this without hard coding it or hand-rolling the code to do this? public class Application { public void Go() { Car c1 = new Car(new FastEngine()); Car c2 = new Car(new SlowEngine()); } } Sample XML: <XML> <Cars> <Car name="c1" engine="FastEngine" /> <Car name="c2" engine="SlowEngine" /> </Cars> </XML>

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  • How to encapsulate a third party complex object structure?

    - by tangens
    Motivation Currently I'm using the java parser japa to create an abstract syntax tree (AST) of a java file. With this AST I'm doing some code generation (e.g.: if there's an annotation on a method, create some other source files, ...) Problem When my code generation becomes more complex, I've to dive deeper into the structure of the AST (e.g. I have to use visitors to extract some type information of method parameters). But I'm not sure if I want to stay with japa or if I will change the parser library later. Because my code generator uses freemarker (which isn't good at automatic refactoring) I want the interface that it uses to access the AST information to be stable, even if I decide to change the java parser. Question What's the best way to encapsulate complex datastructures of third party libraries? I could create my own datatypes and copy the parts of the AST that I need into these. I could create lots of specialized access methods that work with the AST and create exactly the infos I need (e.g. the fully qualified return type of a method as one string, or the first template parameter of a class). I could create wrapper classes for the japa datastructures I currently need and embed the japa types inside, so that I can delegate requests to the japa types and transform the resulting japa types to my wrapper classes again. Which solution should I take? Are there other (better) solutions to this problem?

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  • Why doesn't java.lang.Number implement Comparable?

    - by Julien Chastang
    Does anyone know why java.lang.Number does not implement Comparable? This means that you cannot sort Numbers with Collections.sort which seems to me a little strange. Post discussion update: Thanks for all the helpful responses. I ended up doing some more research about this topic. The simplest explanation for why java.lang.Number does not implement Comparable is rooted in mutability concerns. For a bit of review, java.lang.Number is the abstract super-type of AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, Float, Integer, Long and Short. On that list, AtomicInteger and AtomicLong to do not implement Comparable. Digging around, I discovered that it is not a good practice to implement Comparable on mutable types because the objects can change during or after comparison rendering the result of the comparison useless. Both AtomicLong and AtomicInteger are mutable. The API designers had the forethought to not have Number implement Comparable because it would have constrained implementation of future subtypes. Indeed, AtomicLong and AtomicInteger were added in Java 1.5 long after java.lang.Number was initially implemented. Apart from mutability, there are probably other considerations here too. A compareTo implementation in Number would have to promote all numeric values to BigDecimal because it is capable of accommodating all the Number sub-types. The implication of that promotion in terms of mathematics and performance is a bit unclear to me, but my intuition finds that solution kludgy.

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  • Extending the method pool of a concrete class which is derived by an interface

    - by CelGene
    Hello, I had created an interface to abstract a part of the source for a later extension. But what if I want to extend the derived classes with some special methods? So I have the interface here: class virtualFoo { public: virtual ~virtualFoo() { } virtual void create() = 0; virtual void initialize() = 0; }; and one derived class with an extra method: class concreteFoo : public virtualFoo { public: concreteFoo() { } ~concreteFoo() { } virtual void create() { } virtual void initialize() { } void ownMethod() { } }; So I try to create an Instance of concreteFoo and try to call ownMethod like this: void main() { virtualFoo* ptr = new concreteFoo(); concreteFoo* ptr2 = dynamic_cast(ptr); if(NULL != ptr2) ptr2->ownMethod(); } It works but is not really the elegant way. If I would try to use ptr-ownMethod(); directly the compiler complains that this method is not part of virtualFoo. Is there a chance to do this without using dynamic_cast? Thanks in advance!

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  • WCF data services (OData), query with inheritance limitation?

    - by Mathieu Hétu
    Project: WCF Data service using internally EF4 CTP5 Code-First approach. I configured entities with inheritance (TPH). See previous question on this topic: Previous question about multiple entities- same table The mapping works well, and unit test over EF4 confirms that queries runs smoothly. My entities looks like this: ContactBase (abstract) Customer (inherits from ContactBase), this entity has also several Navigation properties toward other entities Resource (inherits from ContactBase) I have configured a discriminator, so both Customer and Resource map to the same table. Again, everythings works fine on the Ef4 point of view (unit tests all greens!) However, when exposing this DBContext over WCF Data services, I get: - CustomerBases sets exposed (Customers and Resources sets seems hidden, is it by design?) - When I query over Odata on Customers, I get this error: Navigation Properties are not supported on derived entity types. Entity Set 'ContactBases' has a instance of type 'CodeFirstNamespace.Customer', which is an derived entity type and has navigation properties. Please remove all the navigation properties from type 'CodeFirstNamespace.Customer'. Stacktrace: at System.Data.Services.Serializers.SyndicationSerializer.WriteObjectProperties(IExpandedResult expanded, Object customObject, ResourceType resourceType, Uri absoluteUri, String relativeUri, SyndicationItem item, DictionaryContent content, EpmSourcePathSegment currentSourceRoot) at System.Data.Services.Serializers.SyndicationSerializer.WriteEntryElement(IExpandedResult expanded, Object element, ResourceType expectedType, Uri absoluteUri, String relativeUri, SyndicationItem target) at System.Data.Services.Serializers.SyndicationSerializer.<DeferredFeedItems>d__b.MoveNext() at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteItems(XmlWriter writer, IEnumerable`1 items, Uri feedBaseUri) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteFeedTo(XmlWriter writer, SyndicationFeed feed, Boolean isSourceFeed) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteFeed(XmlWriter writer) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteTo(XmlWriter writer) at System.Data.Services.Serializers.SyndicationSerializer.WriteTopLevelElements(IExpandedResult expanded, IEnumerator elements, Boolean hasMoved) at System.Data.Services.Serializers.Serializer.WriteRequest(IEnumerator queryResults, Boolean hasMoved) at System.Data.Services.ResponseBodyWriter.Write(Stream stream) Seems like a limitation of WCF Data services... is it? Not much documentation can be found on the web about WCF Data services (OData) and inheritance specifications. How can I overpass this exception? I need these navigation properties on derived entities, and inheritance seems the only way to provide mapping of 2 entites on the same table with Ef4 CTP5... Any thoughts?

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  • What is wrong with locking non-static fields? What is the correct way to lock a particular instance?

    - by smartcaveman
    Why is it considered bad practice to lock non-static fields? And, if I am not locking non-static fields, then how do I lock an instance method without locking the method on all other instances of the same or derived class? I wrote an example to make my question more clear. public abstract class BaseClass { private readonly object NonStaticLockObject = new object(); private static readonly object StaticLockObject = new object(); protected void DoThreadSafeAction<T>(Action<T> action) where T: BaseClass { var derived = this as T; if(derived == null) { throw new Exception(); } lock(NonStaticLockObject) { action(derived); } } } public class DerivedClass :BaseClass { private readonly Queue<object> _queue; public void Enqueue(object obj) { DoThreadSafeAction<DerivedClass>(x=>x._queue.Enqueue(obj)); } } If I make the lock on the StaticLockObject, then the DoThreadSafeAction method will be locked for all instances of all classes that derive from BaseClass and that is not what I want. I want to make sure that no other threads can call a method on a particular instance of an object while it is locked.

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