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• Updating Android Tab Icons

  - by lnediger

  I have an activity which has a TabHost containing a set of TabSpecs each with a listview containing the items to be displayed by the tab. When each TabSpec is created, I set an icon to be displayed in the tab header. The TabSpecs are created in this way within a setupTabs() method which loops to create the appropriate number of tabs: TabSpec ts = mTabs.newTabSpec("tab"); ts.setIndicator("TabTitle", iconResource); ts.setContent(new TabHost.TabContentFactory( { public View createTabContent(String tag) { ... } }); mTabs.addTab(ts); There are a couple instances where I want to be able to change the icon which is displayed in each tab during the execution of my program. Currently I am deleting all the tabs, and calling the above code again to re-create them. mTabs.getTabWidget().removeAllViews(); mTabs.clearAllTabs(true); setupTabs(); Is there a way to replace the icon that is being displayed without deleting and re-creating all of the tabs?

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• Java - How to declare table[i][j] elements as instance variables?

  - by JDelage

  All, I am trying to code a Connect4 game. For this, I have created a P4Game class and a P4Board class which represents the i X j dimensions of the Connect4 board. In P4Game, I have the following: public class P4Game{ //INSTANCE VARIABLES private int nbLines; private int nbColumns; private P4Board [][] position; //CONSTRUCTOR public P4Game(int nbLines, int nbColumns){ this.nbColumns = nbColumns; this.nbLines = nbLines; P4Board [][] position = new P4Board [nbLines][nbColumns]; //Creates the table to receive the instances of the P4Board object.*/ for (int i=0; i<nbLines; i++){ for (int j=0; j<nbColumns; j++){ this.position[i][j] = new P4Board(i,j); //Meant to create each object at (line=i, column=j) } } } This causes a NullPointerException in the nested loops where I mention this.position[i][j]. I reference those objects in other methods of this class so I need them to be instance variables. I suppose the exception is due to the fact that I have not listed the table element position[i][j] as an instance variable at the beginning of the class. my question to people here is (1) is my assumption correct, and if so (2) what would be the syntax to declare instance variables of this form? Thank you all for your help with what I realize is a very basic question. Hopefully it will also benefit other newbies. Cheers, JDelage

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• iPhone: Does it ever make sense for an object to retain its delegate?

  - by randombits

  According to the rules of memory management in a non garbage collected world, one is not supposed to retain a the calling object in a delegate. Scenario goes like this: I have a class that inherits from UITableViewController and contains a search bar. I run expensive search operations in a secondary thread. This is all done with an NSOperationQueue and subclasses NSOperation instances. I pass the controller as a delegate that adheres to a callback protocol into the NSOperation. There are edge cases when the application crashes because once an item is selected from the UITableViewController, I dismiss it and thus its retain count goes to 0 and dealloc gets invoked on it. The delegate didn't get to send its message in time as the results are being passed at about the same time the dealloc happens. Should I design this differently? Should I call retain on my controller from the delegate to ensure it exists until the NSOperation itself is dealloc'd? Will this cause a memory leak? Right now if I put a retain on the controller, the crashes goes away. I don't want to leak memory though and need to understand if there are cases where retaining the delegate makes sense. Just to recap. UITableViewController creates an NSOperationQueue and NSOperation that gets embedded into the queue. The UITableViewController passes itself as a delegate to NSOperation. NSOperation calls a method on UITableViewController when it's ready. If I retain the UITableViewController, I guarantee it's there, but I'm not sure if I'm leaking memory. If I only use an assign property, edge cases occur where the UITableViewController gets dealloc'd and objc_msgSend() gets called on an object that doesn't exist in memory and a crash is imminent.

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• Handling Application Logic in Multiple AsyncTask onPostExecute()s

  - by stormin986

  I have three simultaneous instances of an AsyncTask for download three files. When two particular ones finish, at the end of onPostExecute() I check a flag set by each, and if both are true, I call startActivity() for the next Activity. I am currently seeing the activity called twice, or something that resembles this type of behavior. Since the screen does that 'swipe left' kind of transition to the next activity, it sometimes does it twice (and when I hit back, it goes back to the same activity). It's obvious two versions of the activity that SHOULD only get called once are being put on the Activity stack. The only way I can find that this is possible is if both AsyncTasks' onPostExecute() executed SO simultaneously that they were virtually running the same lines at the same time, since I set the 'itemXdownloaded' flag to true right before I check for both and call startActivity(). But this is happening enough that it's very hard for me to believe that both downloads are finishing precisely at the same time and having their onPostExecute()s so close together... Any thoughts on what could be going on here? General gist of code (details removed, ignore any syntactical errors I may have edited in): // In onPostExecute() switch (downloadID) { case DL1: dl1complete = true; break; case DL2: dl2complete = true; break; case DL3: dl3complete = true; break; } // If 1 and 2 are done, move on (DL3 still going in background) if ( downloadID != DL3 && dl1complete && dl2complete) { ParentClass.this.startActivity(new Intent(ParentClass.this, NextActivity.class)); }

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• Updating entity fields in app engine development server

  - by Joey

  I recently tried updating a field in one of my entities on the app engine local dev server via the sdk console. It appeared to have updated just fine (a simple float). However, when I followed up with a query on the entity, I received an exception: "Items in the mSomeList list must all be Key instances". mSomeList is just another list field I have in that entity, not the one I modified. Is there any reason manually changing a field would adversely throw something off such that the server gets confused? Is this a known bug? I wrote an http handler to alter the field through server code and it works fine if I take that approach. Update: (adding details) I am using the python google app engine server. Basically if I go into the Google App Engine Launcher and press the SDK Console button, then go into one of my entities and edit a field that is a float (i.e. change it from 0 to 3.5, for instance), I get the "Items in the mMyList list must all be Key instance" suddenly when I query the entity like this: query = DataModels.RegionData.gql("WHERE mRegion = :1", region) entry = query.get() the RegionData entity is what has the mMyList member. As mentioned previously, if I do not manually change the field but rather do so through server code, i.e. query = DataModels.RegionData.gql("WHERE mRegion = :1", region) entry = query.get() entry.mMyFloat = 3.5 entry.put() Then it works.

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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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• SQL different joins not making any difference to result

  - by Chrissi

  I'm trying to write a quick (ha!) program to organise some of my financial information. What I ideally want is a query that will return all records with financial information in them from TableA. There should be one row for each month, but in instances where there were no transactions for a month there will be no record. I get results like this: SELECT Period,Year,TotalValue FROM TableA WHERE Year='1997' Result: Period Year TotalValue 1 1997 298.16 2 1997 435.25 4 1997 338.37 8 1997 336.07 9 1997 578.97 11 1997 361.23 By joining on a table (well a View in this instance) which just contains a field Period with values from 1 to 12, I expect to get something like this: SELECT p.Period,a.Year,a.TotalValue FROM Periods AS p LEFT JOIN TableA AS a ON p.Period = a.Period WHERE Year='1997' Result: Period Year TotalValue 1 1997 298.16 2 1997 435.25 3 NULL NULL 4 1997 338.37 5 NULL NULL 6 NULL NULL 7 NULL NULL 8 1997 336.07 9 1997 578.97 10 NULL NULL 11 1997 361.23 12 NULL NULL What I'm actually getting though is the same result no matter how I join it (except CROSS JOIN which goes nuts, but it's really not what I wanted anyway, it was just to see if different joins are even doing anything). LEFT JOIN, RIGHT JOIN, INNER JOIN all fail to provide the NULL records I am expecting. Is there something obvious that I'm doing wrong in the JOIN? Does it matter that I'm joining onto a View?

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• sql server mdf file database attachment

  - by jnsohnumr

  hello all i'm having a bear of a time getting visual studio 2010 (ultimate i think) to properly attach to my database. it was moved from original spot to #MYAPP#/#MYAPP#.Web/App_Data/#MDF_FILE#.mdf. I have three instances of sql server running on this machine. i have tried to replace the old mdf file with my new one and cannot get the connectionstring right for it. what i'm really wanting to do is to just open some DB instance, run a DB create script. Then I can have a DB that was generated via my edmx (generate database from model) in silverlight business application (c#) right now, when i go to server explorer in VS, choose add new connection, choose MS SQL Server Database FIle (SqlClient), choose my file location (app_data directory), use windows authentication, and hit the Test Connection button I get the following error: Unable to open the physical file "". Operating system error 5: "5(Access Denied.)". An attempt to attach to an auto-named database for file"" failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share. The mdf file was created on the same machine by connecting to (local) on the sql server management studio, getting a new query, pasting in the SQL from the generated ddl file, adding a CREATE DATABASE [NcrCarDatabase]; GO before the pasted SQL, and executing the query. I then disconnected from the DB in management studio, closed management studio, navigated to the DATA directory for that instance, and copying the mdf and ldf files to my application's app_data folder. I am then trying to connect to the same file inside visual studio. I hope that gives more clarity to my problems :). Connection string is: Data Source=.\SQLEXPRESS;AttachDbFilename=C:\SourceCode\NcrCarDatabase\NcrCarDatabase.Web\App_Data\NcrCarDatabase.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True

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• How do I add code automatically to a derived function in C++

  - by Ian

  I have code that's meant to manage operations on both a networked client and a server, since there is significant overlap between the two. However, there are a few functions here and there that are meant to be exclusively called by the client or server, and accidentally calling a client function on the server (or vice versa) is a significant source of bugs. To reduce these sorts of programming errors, I'm trying to tag functions so that they'll raise a ruckus if they're misused. My current solution is a simple macro at the start of each function that calls an assert if the client or server accesses members they shouldn't. However, this runs into problems when there are multiple derived instances of classes, in that I have to tag the implementation as client or server side in EVERY child class. What I'd like to be able to do is put a tag in the virtual member's signature in the base class, so that I only have to tag it once and not run into errors by forgetting to do it repeatedly. I've considered putting a check in a base class implementation and then referring to it with something like base::functionName, but that runs into the same issue as far as needing to manually add the function call to every implementation. Ideally, I'd be able to have parent versions of the function called automatically like default constructors do. Does anybody know how to achieve something like this in C++? Is there an alternate approach I should be considering? Thanks!

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• How to use the `itemDoubleClicked(QTreeWidgetItem*,int)` signal in qtHaskell

  - by nano

  I want to use the itemDoubleClicked(QTreeWidgetItem*,int) signal in a Haskell program I'm writing where I am using qtHaskell for the GUI. To connect a function I have at other places done the following: dummyWidget <- myQWidget connectSlot object signal dummyWidget "customSlot()" $ f Where object is some QWidget and signal is a string giving the signal, e.g. "triggered()", and f is the function I want to be called when the signaled is send. The definition of connectSlot in the API is: class Qcs x where connectSlot :: QObject a -> String -> QObject b -> String -> x -> IO () where the instances ofQcs are: Qcs () Qcs (QObject c -> String -> IO ()) Qcs (QObject c -> Object d -> IO ()) Qcs (QObject c -> Bool -> IO ()) Qcs (QObject c -> Int -> IO ()) Qcs (QObject c -> IO ()) Qcs (QObject c -> OpenGLVersionFlag -> IO ()) The first Arguments passed is supposed to be the QObject of which I'm using a signal. As you can see, there is no instance where f, the function to connect to the signal, can have two further arguments to recieve the QWidget and the integer send by the signal. Is there a way to nevertheless connect that signal to a custom function?

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• How do I create a class repository in Java and do I really need it?

  - by Roman

  I have a large number of objects which are identified by names (strings). So, I would like to have a kind of mapping from object name to the class instances. I was told that in this situation I can use a "repository" class which works like that: Server myServer = ServerRepository.getServer("NameOfServer"); So, if there is already an object (sever) with the "NameOfServer" it will be returned by the "getServer". If such an object does not exist yet, it will be created and returned by the "getServer". So, my question is how to program such a "repository" class? In this class I have to be able to check if there is an instance of a given class such that it has a given value of a given field. How can I do it? I need to have a kind of loop over all existing object of a given class? Another part of my question is why I cannot use associative arrays (associative container, map, mapping, dictionary, finite map)? (I am not sure how do you call it in Java) In more details, I have an "array" which maps names of objects to objects. So, whenever I create a new object, I add a new element to the array: myArray["NameOfServer"] = new Server("NameOfServer").

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• WPF and LINQ/SQL - how and where to keep track of changes?

  - by Groky

  I have a WPF application built using the MVVM pattern: My Models come from LINQ to SQL. I use the Repository Pattern to abstract away the DataContext. My ViewModels have a reference to a Model. Setting a property on the ViewModel causes that value to be written through to the Model. As you can see, my data is stored in my Model, and changes are therefore tracked by my DataContext. However, in this question I read: The guidelines from the MSDN documentation on the DataContext class are what I would recommend following: In general, a DataContext instance is designed to last for one "unit of work" however your application defines that term. A DataContext is lightweight and is not expensive to create. A typical LINQ to SQL application creates DataContext instances at method scope or as a member of short-lived classes that represent a logical set of related database operations. How do you track your changes? In your DataContext? In your ViewModel? Elsewhere?

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• Debugged Program Window Won't Close

  - by Marc Bernier

  Hi, I'm using VS 2008 on a 64-bit XP machine. I'm debugging a 32-bit C++ DLL via a console program. The DLL and EXE projects are contained in the same SLN so that I can modify the DLL as I test. What happens is that every once in a while I kill the program with Debug | Stop Debugging (Shift-F5). VS stops the program, but the console window stays open! If I'm sitting at a breakpoint and hit Shift-F5, it will terminate properly, but if the program is running full-tilt when I stop it, I often see this instead. The big problem is that I can't close these zombie windows. Using End Task in Task Manager does nothing (no message, no nothing). When I shut down the machine, it is unable to due to the orphans and I have to resort to actually turning off the power. I think this is connected to having the DLL and EXE project in the same SLN, as for months I worked on this project in 2 VS instances, one for the DLL and the other for the EXE. I would continually jump back and forth between the windows as I worked. This problem never happened until I put the two projects into a single SLN. The single SLN works a lot better, but this anomaly is very irritating. Any ideas anyone? UPDATE After a bit of searching (here), I found that it appears to have to do with one of the updates from last Tuesday (KB977165 or KB978037). Thank you Microsoft for your excellent pre-release testing.

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• Trait, FunctionN, or trait-inheriting-FunctionN in Scala?

  - by Willis Blackburn

  I have a trait in Scala that has a single method. Call it Computable and the single method is compute(input: Int): Int. I can't figure out whether I should Leave it as a standalone trait with a single method. Inherit from (Int = Int) and rename "compute" to "apply." Just get rid of Computable and use (Int = Int). A factor in favor of it being a trait is that I could usefully add some additional methods. But of course if they were all implemented in terms of the compute method then I could just break them out into a separate object. A factor in favor of just using the function type is simplicity and the fact that the syntax for an anonymous function is more concise than that for an anonymous Computable instance. But then I've no way to distinguish objects that are actually Computable instances from other functions that map Int to Int but aren't meant to be used in the same context as Computable. How do other people approach this type of problem? No right or wrong answers here; I'm just looking for advice.

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• Strange JPA one-to-many behavior when trying to set the "many" on the "one" entity

  - by errr

  I've mapped two entities using JPA (specifically Hibernate). Those entities have a one-to-many relationship (I've simplified for presentation): @Entity public class A { @ManyToOne public B getB() { return b; } } @Entity public Class B { @OneToMany(mappedBy="b") public Set<A> getAs() { return as; } } Now, I'm trying to create a relationship between two instances of these entities by using the setter of the one-side/not-owner-side of the relationship (i.e the table being referenced to): em.getTransaction().begin(); A a = new A(); B b = new B(); Set<A> as = new HashSet<A>(); as.add(a); b.setAs(as); em.persist(a); em.persist(b); em.getTransaction().commit(); But then, the relationship isn't persisted to the DB (the row created for entity A isn't referencing the row created for entity B). Why is it so? I'd excpect it to work. Also, if I remove the "mappedBy" property from the @OneToMany annotation it will work. Again - why is it so? and what are the possible effects for removing the "mappedBy" property?

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• Finding multiple values in a string Jquery / Javascript

  - by user257503

  I have a three strings of categories "SharePoint,Azure,IT"; "BizTalk,Finance"; "SharePoint,Finance"; I need to find a way to check if a string contains for example "SharePoint" and "IT", or "BizTalk" and "Finance". The tests are individual strings themselces. How would i loop through all the category strings (1 - 3) and only return the ones which have ALL instances of the souce. i have tried the following function doesExist(source, filterArray) { var substr = filterArray.split(" "); jQuery.each(substr, function() { var filterTest = this; if(source.indexOf(filterTest) != -1 ) { alert("true"); return true; }else { alert("false"); return false; } }); } with little success...the code above checks one at a time rather than both so the results returned are incorrect. Any help would be great. Thanks Chris UPDATE: here is a link to a work in progress version..http://www.invisiblewebdesign.co.uk/temp/filter/#

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• How to design data storage for partitioned tagging system?

  - by Morgan Cheng

  How to design data storage for huge tagging system (like digg or delicious)? There is already discussion about it, but it is about centralized database. Since the data is supposed to grow, we'll need to partition the data into multiple shards soon or later. So, the question turns to be: How to design data storage for partitioned tagging system? The tagging system basically has 3 tables: Item (item_id, item_content) Tag (tag_id, tag_title) TagMapping(map_id, tag_id, item_id) That works fine for finding all items for given tag and finding all tags for given item, if the table is stored in one database instance. If we need to partition the data into multiple database instances, it is not that easy. For table Item, we can partition its content with its key item_id. For table Tag, we can partition its content with its key tag_id. For example, we want to partition table Tag into K databases. We can simply choose number (tag_id % K) database to store given tag. But, how to partition table TagMapping? The TagMapping table represents the many-to-many relationship. I can only image to have duplication. That is, same content of TagMappping has two copies. One is partitioned with tag_id and the other is partitioned with item_id. In scenario to find tags for given item, we use partition with tag_id. If scenario to find items for given tag, we use partition with item_id. As a result, there is data redundancy. And, the application level should keep the consistency of all tables. It looks hard. Is there any better solution to solve this many-to-many partition problem?

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• How to determine which inheriting class is using an abstract class's methods.

  - by Kin

  In my console application have an abstract Factory class "Listener" which contains code for listening and accepting connections, and spawning client classes. This class is inherited by two more classes (WorldListener, and MasterListener) that contain more protocol specific overrides and functions. I also have a helper class (ConsoleWrapper) which encapsulates and extends System.Console, containing methods for writing to console info on what is happening to instances of the WorldListener and MasterListener. I need a way to determine in the abstract ListenerClass which Inheriting class is calling its methods. Any help with this problem would be greatly appreciated! I am stumped :X Simplified example of what I am trying to do. abstract class Listener { public void DoSomething() { if(inheriting class == WorldListener) ConsoleWrapper.WorldWrite("Did something!"); if(inheriting class == MasterListener) ConsoleWrapper.MasterWrite("Did something!"); } } public static ConsoleWrapper { public void WorldWrite(string input) { System.Console.WriteLine("[World] {0}", input); } } public class WorldListener : Listener { public void DoSomethingSpecific() { ConsoleWrapper.WorldWrite("I did something specific!"); } } public void Main() { new WorldListener(); new MasterListener(); } Expected output [World] Did something! [World] I did something specific! [Master] Did something! [World] I did something specific!

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• Javascript to fire event when a key pressed on the Ajax Toolkit Combo box.

  - by Paul Chapman

  I have the following drop down list which is using the Ajax Toolkit to provide a combo box <cc1:ComboBox ID="txtDrug" runat="server" style="font-size:8pt; width:267px;" Font-Size="8pt" DropDownStyle="DropDownList" AutoCompleteMode="SuggestAppend" AutoPostBack="True" ontextchanged="txtDrug_TextChanged" /> Now I need to load this up with approx 7,000 records which takes a considerable time, and effects the response times when the page is posted back and forth. The code which loads these records is as follows; dtDrugs = wsHelper.spGetAllDrugs(); txtDrug.DataValueField = "pkDrugsID"; txtDrug.DataTextField = "drugName"; txtDrug.DataSource = dtDrugs; txtDrug.DataBind(); However if I could get an event to fire when a letter is typed instead of having to load 7000 records it is reduced to less than 50 in most instances. I think this can be done in Javascript. So the question is how can I get an event to fire such that when the form starts there is nothing in the drop down, but as soon as a key is pressed it searches for those records starting with that letter. The .Net side of things I'm sure about - it is the Javascript I'm not. Thanks in advance

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• How big can I make an Android application's canvas in terms of pixels?

  - by user279112

  I've determined an estimate of the size of my Android emulator's screen in pixels, although I think its resolution can be changed to other numbers. Quite frankly though that doesn't eliminate the general problem of not knowing how many pixels on each axis I have to work with on my Android applications in general. The main problem I'm trying to solve is this: How do I make sure I don't use a faulty resolution on Android applications if I want to keep things' sizes constant (so that if the application screen shrinks, for instances, objects will still show up just as big - there just won't be as many of them being shown) if I wish to do this with a single universal resolution for each program? Failing that, how do I make sure everything's alright if I try to do everything the same way with maybe a few different pre-set resolutions? Mainly it seems like a relevant question that must be answered before I can come across a complete answer for the general problem is how big can I always make my application in pixels, NOT regarding if and when a user resizes the application's screen to something smaller than the maximum size permitted by the phone and its operating system. I really want to try to keep this simple. If I were doing this for a modern desktop, for instance, I know that if I design the application with a 800x600 canvas, the user can still shrink the application to the point they're not doing themselves any favors, but at least I can basically count on it working right and not being too big for the monitor or something. Is there such a magic resolution for Android, assuming that I'm designing for API levels 3+ (Android 1.5+)? Thanks

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• Comparing Object properties using reflection

  - by Kumar

  I have two classes Address and Employee as follows: public class Address { public string AddressLine1 { get; set; } public string AddressLine2 { get; set; } public string City { get; set; } public string State { get; set; } public string Zip { get; set; } } public class Employee { public string FirstName { get; set; } public string MiddleName { get; set; } public string LastName { get; set; } public Address EmployeeAddress { get; set; } } I have two employee instances as follows: var emp1Address = new Address(); emp1Address.AddressLine1 = "Microsoft Corporation"; emp1Address.AddressLine2 = "One Microsoft Way"; emp1Address.City = "Redmond"; emp1Address.State = "WA"; emp1Address.Zip = "98052-6399"; var emp1 = new Employee(); emp1.FirstName = "Bill"; emp1.LastName = "Gates"; emp1.EmployeeAddress = emp1Address; var emp2Address = new Address(); emp2Address.AddressLine1 = "Gates Foundation"; emp2Address.AddressLine2 = "One Microsoft Way"; emp2Address.City = "Redmond"; emp2Address.State = "WA"; emp2Address.Zip = "98052-6399"; var emp2 = new Employee(); emp2.FirstName = "Melinda"; emp2.LastName = "Gates"; emp2.EmployeeAddress = emp2Address; Now how can I write a method which compares these two employees and returns the list of properties which have different values. So in this example I would like the result to be FirstName and Address.AddressLine1 .

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• Alternatives to static methods on interfaces for enforcing consistency

  - by jayshao

  In Java, I'd like to be able to define marker interfaces, that forced implementations to provide static methods. For example, for simple text-serialization/deserialization I'd like to be able to define an interface that looked something like this: public interface TextTransformable<T>{ public static T fromText(String text); public String toText(); Since interfaces in Java can't contain static methods though (as noted in a number of other posts/threads: here, here, and here this code doesn't work. What I'm looking for however is some reasonable paradigm to express the same intent, namely symmetric methods, one of which is static, and enforced by the compiler. Right now the best we can come up with is some kind of static factory object or generic factory, neither of which is really satisfactory. Note: in our case our primary use-case is we have many, many "value-object" types - enums, or other objects that have a limited number of values, typically carry no state beyond their value, and which we parse/de-parse thousands of time a second, so actually do care about reusing instances (like Float, Integer, etc.) and its impact on memory consumption/g.c. Any thoughts?

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• Do all the HTML5 storage systems work together ?

  - by azera

  While there are a lot of good stuff about html5, one thing I don't get is the redondant storage mechanism, first there is localstorage and sessionstorage, which are key value stores, one is for one instance of the app ("one tab"), and the other works for all the instances of that application so they can share data. Both are saved when you close your browser and have a limited size (usually 5MB), that's great and everything would be nice if we stopped there. But then there is the "Web SQL Database", which has the same security system as the localstorage, the same size limit, the same everything except it works like/is sqlite, with tables and sql syntax and all of that. And the bummer is, they don't work on the same data at all ! This is not two way to access your data, this is really two storage for every html 5 app out there (not created by default yes, but still you see my point). What I would like to know is, is there a reason for both of this mechanisms to exist at the same time ? Or did they just look at sql and nosql movement to pick the best then went "screw it let's add both !" ? Why not implement local/session storage as a table inside web sql db ?

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• PHP OOP: Avoid Singleton/Static Methods in Domain Model Pattern

  - by sunwukung

  I understand the importance of Dependency Injection and its role in Unit testing, which is why the following issue is giving me pause: One area where I struggle not to use the Singleton is the Identity Map/Unit of Work pattern (Which keeps tabs on Domain Object state). //Not actual code, but it should demonstrate the point class Monitor{//singleton construction omitted for brevity static $members = array();//keeps record of all objects static $dirty = array();//keeps record of all modified objects static $clean = array();//keeps record of all clean objects } class Mapper{//queries database, maps values to object fields public function find($id){ if(isset(Monitor::members[$id]){ return Monitor::members[$id]; } $values = $this->selectStmt($id); //field mapping process omitted for brevity $Object = new Object($values); Monitor::new[$id]=$Object return $Object; } $User = $UserMapper->find(1);//domain object is registered in Id Map $User->changePropertyX();//object is marked "dirty" in UoW // at this point, I can save by passing the Domain Object back to the Mapper $UserMapper->save($User);//object is marked clean in UoW //but a nicer API would be something like this $User->save(); //but if I want to do this - it has to make a call to the mapper/db somehow $User->getBlogPosts(); //or else have to generate specific collection/object graphing methods in the mapper $UserPosts = $UserMapper->getBlogPosts(); $User->setPosts($UserPosts); Any advice on how you might handle this situation? I would be loathe to pass/generate instances of the mapper/database access into the Domain Object itself to satisfy DI - At the same time, avoiding that results in lots of calls within the Domain Object to external static methods. Although I guess if I want "save" to be part of its behaviour then a facility to do so is required in its construction. Perhaps it's a problem with responsibility, the Domain Object shouldn't be burdened with saving. It's just quite a neat feature from the Active Record pattern - it would be nice to implement it in some way.

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• Is there anything bad in declaring static inner class inside interface in java?

  - by Roman

  I have an interface ProductService with method findByCriteria. This method had a long list of nullable parameters, like productName, maxCost, minCost, producer and so on. I refactored this method by introducing Parameter Object. I created class SearchCriteria and now method signature looks like this: findByCriteria (SearchCriteria criteria) I thought that instances of SearchCriteria are only created by method callers and are only used inside findByCriteria method, i.e.: void processRequest() { SearchCriteria criteria = new SearchCriteria () .withMaxCost (maxCost) ....... .withProducer (producer); List<Product> products = productService.findByCriteria (criteria); .... } and List<Product> findByCriteria(SearchCriteria criteria) { return doSmthAndReturnResult(criteria.getMaxCost(), criteria.getProducer()); } So I did not want to create separate public class for SearchCriteria and put it inside ProductServiceInterface: public interface ProductService { List<Product> findByCriteria (SearchCriteria criteria); static class SearchCriteria { ... } } Is there anything bad in this interface? Where whould you place SearchCriteria class?

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