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• Help understanding .NET delegates, events, and eventhandlers

  - by Seth Spearman

  Hello, In the last couple of days I asked a couple of questions about delegates HERE and HERE. I confess...I don't really understand delegates. And I REALLY REALLY REALLY want to understand and master them. (I can define them--type safe function pointers--but since I have little experience with C type languages it is not really helpful.) Can anyone recommend some online resource(s) that will explain delegates in a way that presumes nothing? This is one of those moments where I suspect that VB actually handicaps me because it does some wiring for me behind the scenes. The ideal resource would just explain what delegates are, without reference to anything else like (events and eventhandlers), would show me how all everything is wired up, explain (as I just learned) that delegates are types and what makes them unique as a type (perhaps using a little ildasm magic)). That foundation would then expand to explain how delegates are related to events and eventhandlers which would need a pretty good explanation in there own right. Finally this resource could tie it all together using real examples and explain what wiring DOES happen automatically by the compiler, how to use them, etc. And, oh yeah, when you should and should not use delegates, in other words, downsides and alternatives to using delegates. What say ye? Can any of you point me to resource(s) that can help me begin my journey to mastery? EDIT One last thing. The ideal resource will explain how you can and cannot use delegates in an interface declaration. That is something that really tripped me up. Thanks for your help. Seth

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• Trouble getting $.ajax() to work in PhoneGap against a locally hosted server

  - by David Gutierrez

  Currently trying to make an ajax post request to an IIS Express hosted MVC 4 Web API end point from an android VM (Bluestacks) on my machine. Here are the snippets of code that I am trying, and cannot get to work: $.ajax({ type: "POST", url: "http://10.0.2.2:28434/api/devices", data: {'EncryptedPassword':'1234','UserName':'test','DeviceToken':'d234'} }).always(function( data, textStatus, jqXHR ) { alert( textStatus ); }); Whenever I run this request I always get back a textStatus of 'error'. After hours of trying different things, I pushed my End Point to an actual server, and was able to actually get responses back in PhoneGap if I built up an XMLHttpRequest by hand, like so: var request = new XMLHttpRequest(); request.open("POST", "http://172.16.100.42/MobileRewards/api/devices", true); request.onreadystatechange = function(){//Call a function when the state changes. console.log("state = " + request.readyState); console.log("status = " + request.status); if (request.readyState == 4) { if (request.status == 200 || request.status == 0) { console.log("*" + request.responseText + "*"); } } } request.send("{EncryptedPassword:1234,UserName:test,DeviceToken:d234}"); Unfortunately, if I try to use $.ajax() against the same end point in the snippet above I still get a status text that says 'error', here is that snippet for reference: $.ajax({ type: "POST", url: "http://172.16.100.42/MobileRewards/api/devices", data: {'EncryptedPassword':'1234','UserName':'test','DeviceToken':'d234'} }).always(function( data, textStatus, jqXHR ) { alert( textStatus ); }); So really, there are a couple of questions here. 1) Why can't I get any ajax calls (post or get) to successfully hit my End Point when it's hosted via IIS Express on the same machine that the Android VM is running? 2) When my end point is hosted on an actual server, through IIS and served through port 80, why can't I get post requests to be successful when I use jquery's ajax calls? (Even though I can get it to work by manually creating an XMLHttpRequest) Thanks

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• Beginner's guide for rails

  - by piemesons

  Hello friends i need a book/ tutorials for rails without using scoffold. All the books mentioned in the other questions are creating some depot application or etc using scaffold and then explaining things. I believe in the thing that creating big depot is worthless when you are not getting anything. All of my frnds are suggesting me to go for this pragmatic book. look i understand the book is good but i m not getting the proper things. I got the logic cause i m good in php doctrine. asp.net c c++ so i m getting the things but i m not feeling confident. I want to have a another book. Can anybody suggest me some other books. I m saying this cause it really feels good when u create a simple form and insert the values in db and u can retreive those values and MOST IMP you can explain the whole logic of the that small form application instaed of that colorfull Depot application in which things are done with scaffold and u r not getting the thing and u are confused abt the real picture.

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• How should I start to play with 3D

  - by MarceloRamires

  I'm a developer for just about 6 months now, and since I enjoy programming I make a couple of little programs. I've startedmaking encripters, calculators, tools, stuff to play with DropBox (hehe), stuff that play with bitmaps, drawing graphics, and even a program to update the MSN display image according to the artwork of the music you're listening yo on iTunes. Now I kind of ran off ideas of programs to deal with information, and I've had an idea: play around with 3d! so I've read a little about it and figured I'd have to have good notions on position and math on point spacial position (which I do, from my 3d modelling experience), but I don't know how to use API's for it, so I've 'simulated' simple 3d with a simple program I've made (it's just a spinning cube, please, first one to open it, comment here stating that it's safe, i've got no reason to harm anyone's pc.) One of my other hobbies is 3d modelling (completly amateur) and I'd like to mix these hobbies together! Here are some questions: 1) What would be a nice 3d development tool for a .NET programmer like me? 2) Is there a way of using 3d models made in 3DS Max ? (I intend on modelling characters) 3) What knowledges should I have in order to render it, and move it areound ? 4) Which API should I use ? NOTE: Not a dupe, I'm asking for directions specific for .NET development possibly using 3ds MAX, and there's no question about it!

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• Static library woes in iPhone 3.x with categories and C libraries

  - by hgpc

  I have a static library (let's call it S) that uses a category (NSData+Base64 from MGTwitterEngine) and a C library (MiniZip wrapped by ZipArchive). This static library is used in an iPhone 3.x project (let's call it A). To be able to use the MiniZip library I included its files in project A as well as the static library S. If not I get compilation errors. Project A works fine on the simulator. When I run it on the device, I get unrecognized selector errors when the category is used. As pointed out here, it seems there's a linker bug that affects categories in iPhone 3.x (http://stackoverflow.com/questions/1147676/categories-in-static-library-for-iphone-device-3-0). The workaround is to add -all_load to the Other Linker Flags of the project that references the static library. However, if I do this then I get duplicate symbol errors because I included the MiniZip libraries in project A. A workaround is to include the category files in project A as well. If I do this, project A works well in the device, but fails to build on the simulator because of duplicate symbol errors. How should I set up project A to make it work on the simulator and the device with the same configuration?

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• tipfy for Google App Engine: Is it stable? Can auth/session components of tipfy be used with webapp?

  - by cv12

  I am building a web application on Google App Engine that requires users to register with the application and subsequently authenticate with it and maintain sessions. I don't want to force users to have Google accounts. Also, the target audience for the application is the average non-geek, so I'm not very keen on using OpenID or OAuth. I need something simple like: User registers with an e-mail and password, and then can log back in with those credentials. I understand that this approach does not provide the security benefits of Google or OpenID authentication, but I am prepared to trade foolproof security for end-user convenience and hassle-free experience. I explored Django, but decided that consecutive deprecations from appengine-helper to app-engine-patch to django-nonrel may signal that path may be a bit risky in the long-term. I'd like to use a code base that is likely to be maintained consistently. I also explored standalone session/auth packages like gaeutilities and suas. GAEUtilities looked a bit immature (e.g., the code wasn't pythonic in places, in my opinion) and SUAS did not give me a lot of comfort with the cookie-only sessions. I could be wrong with my assessment of these two, so I would appreciate input on those (or others that may serve my objective). Finally, I recently came across tipfy. It appears to be based on Werkzeug and Alex Martelli spoke highly of it here on stackoverflow. I have two primary questions related to tipfy: As a framework, is it as mature as webapp? Is it stable and likely to be maintained for some time? Since my primary interest is the auth/session components, can those components of the tipfy framework be used with webapp, independent of the broader tipfy framework? If yes, I would appreciate a few pointers to how I could go about doing that.

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• How to handle large dataset with JPA (or at least with Hibernate)?

  - by Roman

  I need to make my web-app work with really huge datasets. At the moment I get either OutOfMemoryException or output which is being generated 1-2 minutes. Let's put it simple and suppose that we have 2 tables in DB: Worker and WorkLog with about 1000 rows in the first one and 10 000 000 rows in the second one. Latter table has several fields including 'workerId' and 'hoursWorked' fields among others. What we need is: count total hours worked by each user; list of work periods for each user. The most straightforward approach (IMO) for each task in plain SQL is: 1) select Worker.name, sum(hoursWorked) from Worker, WorkLog where Worker.id = WorkLog.workerId group by Worker.name; //results of this query should be transformed to Multimap<Worker, Long> 2) select Worker.name, WorkLog.start, WorkLog.hoursWorked from Worker, WorkLog where Worker.id = WorkLog.workerId; //results of this query should be transformed to Multimap<Worker, Period> //if it was JDBC then it would be vitally //to set resultSet.setFetchSize (someSmallNumber), ~100 So, I have two questions: how to implement each of my approaches with JPA (or at least with Hibernate); how would you handle this problem (with JPA or Hibernate of course)?

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• Beyond core java

  - by Paul

  Coming to the end of the first year of my CS degree, we've done some Java but just the core stuff; manipulating strings and arrays, inheritance, implementing logic etc. I visit this website daily and I see so much stuff that is beyond me; using frameworks; managing databases etc. It makes me feel like I've just learned the syntax of Java, and there is so much more to do with it. My question is though, how do I get there? I don't think I'm advanced enough to join an open source project, which seems to be suggested often (though I'd love to) and I've looked at other similar questions on here (like this one) but even then I don't think that'd work for me.. firstly, could somebody try give me some commonly used frameworks etc and how and what they are used for? Where would be a good place to start? How did you get started in using the things you do? Or perhaps you think I'm going down the wrong route. Should I learn another language, and just wait until the moment occurs where it's clear what I should be doing? I'm only in the first year of my degree, so far we've lightly covered Haskell and Java, and I've done a little HTML and CSS in my free time. I know that next year we cover python, so perhaps I should just wait till then and see if I prefer that? I feel like I also risk learning something in depth and then never using it... I suppose I'm also asking for personal experiences; was there a point where you felt you'd exceeded the basic grasp of a language (does not necessarily have to be Java related) and reach a more "advanced" level? I guess I'll put subjective tag on this, but really I just want to know how to get beyond the basic understanding of a language.

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• Delphi App has "No Debug Info" when Debugging

  - by James L.

  We have built an application that uses packages and components. When we debug the application, the "Event Log" in the IDE often shows the our BPLs are being loaded without debug information ("No Debug Info"). This doesn't make sense because all our packages and EXEs are built with debug. _(each project) | Options | Compiling_ [ x ] Assertions [ x ] Debug information [ x ] Local symbols Symbol reference info = "Reference info" [ ] Use debug .dcus [ x ] Use imported data references _(each project) | Options | Linking_ [ x ] Debug information Map file = Detailed We have 4 projects, all built with runtime pacakges: Core.bpl Components.bpl Plugin.bpl (uses both #1 & #2) MainApp.exe (uses #1) Problems Observed 1) Many times when we debug, the Components.bpl is loaded with debug info, but all values in the "Local Variables" window are blank. If you hover your mouse over a variable in the code, there is no popup, and Evaluate window also shows nothing (the "Result" pane is always blank). 2) Sometimes the Event Log shows "No Debug Info" for various BPLs. For instance, if we activate the Plugin.bpl project and set it's Run | Parameter's Host Application to be the MainApp.exe, and then press F9, all modules seems to load with "Has Debug Info" except for the Plugin.bpl module. When it loads, the Event Log shows "No Debug Info". However, if we close the app and immediately press F9, it will run it again without recompiling anything and this time Plugin.bpl is loaded with debug ("Has Debug Info"). Questions 1) What would cause the "Local Variables" window to not display the values? 2) Why are BPLs sometimes loaded without debug info when the BPL was complied with debug and all the debug files (dcu, map, etc.) are available?

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• Write a sql for updating data based on time

  - by Lu Lu

  Hello everyone, Because I am new with SQL Server and T-SQL, so I will need your help. I have 2 table: Realtime and EOD. To understand my question, I give example data for 2 tables: ---Realtime table--- Symbol Date Value ABC 1/3/2009 03:05:01 327 // this day is not existed in EOD -> inserting BBC 1/3/2009 03:05:01 458 // this day is not existed in EOD -> inserting ABC 1/2/2009 03:05:01 326 // this day is new -> updating BBC 1/2/2009 03:05:01 454 // this day is new -> updating ABC 1/2/2009 02:05:01 323 BBC 1/2/2009 02:05:01 453 ABC 1/2/2009 01:05:01 313 BBC 1/2/2009 01:05:01 423 ---EOD table--- Symbol Date Value ABC 1/2/2009 02:05:01 323 BBC 1/2/2009 02:05:01 453 I will need to create a store procedure to update value of symbols. If data in day of a symbol is new (compare between Realtime & EOD), it will update value and date for EOD at that day if existing, otherwise inserting. And store will update EOD table with new data: ---EOD table--- Symbol Date Value ABC 1/3/2009 03:05:01 327 BBC 1/3/2009 03:05:01 458 ABC 1/2/2009 03:05:01 326 BBC 1/2/2009 03:05:01 454 P/S: I use SQL Server 2005. And I have a similar answered question at here: http://stackoverflow.com/questions/2726369/help-to-the-way-to-write-a-query-for-the-requirement Please help me. Thanks.

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• Set Property Value on Master Page from Content Page

  - by Merk

  Hello, I tried following the advice posted here: http://stackoverflow.com/questions/1071920/set-property-value-on-master-page-from-content-page. Specifically the last post about creating a class. However, visual studio keeps giving me an error on my default.aspx.cs page when i try to set the value: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class _Default : BasePage { protected override int NavHighlight { get { return new{0} ; } } protected void Page_Load(object sender, EventArgs e) { } } It throws an error on new, the error being: cannot inplicity convert anonymoustype#1 to int Can someone tell me what i might have done wrong here? Here's what my class looks like: using System; using System.Collections.Generic; using System.Linq; using System.Web; /// <summary> /// Summary description for BasePage /// </summary> public abstract class BasePage : System.Web.UI.Page { protected abstract int NavHighlight { get; } protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (this.Master != null) { //value assignment } } public BasePage() { // // TODO: Add constructor logic here // } } Thanks.

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• WCF: Using multiple bindings for a single service.

  - by Lijo

  Hi, I have a WCF service (in 3.0) which is running fine with wsHttpBinding. I want to add netTcpBinding binding also to the same service. But the challenge that I am facing is in adding behaviorConfiguration. How should I modify the following code to enable the service for both the bindings? Please help… <service name="Lijo.Samples.WeatherService" behaviorConfiguration="WeatherServiceBehavior"> <host> <baseAddresses> <add baseAddress="http://localhost:8000/ServiceModelSamples/FreeServiceWorld"/> <add baseAddress="net.tcp://localhost:8052/ServiceModelSamples/FreeServiceWorld"/> <!-- added new baseaddress for TCP--> </baseAddresses> </host> <endpoint address="" binding="wsHttpBinding" contract="Lijo.Samples.IWeather" /> <endpoint address="" binding="netTcpBinding" contract="Lijo.Samples.IWeather" /> <!-- added new end point--> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services> <behaviors> <serviceBehaviors> <behavior name="WeatherServiceBehavior"> <serviceMetadata httpGetEnabled="true"/> <serviceDebug includeExceptionDetailInFaults="False"/> </behavior> </serviceBehaviors> </behaviors> Please see the following to see further details http://stackoverflow.com/questions/2887588/wcf-using-windows-service Thanks Lijo

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• Question about passing data using intents

  - by Joe K 1973

  Hi everyone, I'm trying to modify the Notepad tutorial (the Notepadv3 solution) to take in a value into the NoteEdit class, given to by the Notepadv3 class. I've successfully used .putExtra in the OnListItemClick method to place the value into the NoteEdit class, but I'm struggling to do this for the createNote method; I'm getting a force close when I try to create a new note. I bet there's a simple solution, but I'm pretty new to Java & Android and would very much appreciate your help. Here's the code in question in the Notepadv3 class: private void createNote() { Intent i = new Intent(this, NoteEdit.class); i.putExtra("key", 1); startActivityForResult(i, ACTIVITY_CREATE); } @Override protected void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); Intent i = new Intent(this, NoteEdit.class); i.putExtra(NotesDbAdapter.KEY_ROWID, id); i.putExtra("key", 1); startActivityForResult(i, ACTIVITY_EDIT); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent intent) { super.onActivityResult(requestCode, resultCode, intent); fillData(); } And here's the receiving code in the NoteEdit class: mRowId = savedInstanceState != null ? savedInstanceState.getLong(NotesDbAdapter.KEY_ROWID) : null; if (mRowId == null) { Bundle extras = getIntent().getExtras(); mRowId = extras != null ? extras.getLong(NotesDbAdapter.KEY_ROWID) : null; value = extras.getInt("key"); } I'm fairly sure that (mRowId == null) is not true when I'm using the createNote method so therefore getExtras won't be called. One of my questions would be how can I make my NoteEdit class get this value when I use the createNote method? I'm new to this so sorry if this is a simple question for you all. Thanks, Joe

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• non-copyable objects and value initialization: g++ vs msvc

  - by R Samuel Klatchko

  I'm seeing some different behavior between g++ and msvc around value initializing non-copyable objects. Consider a class that is non-copyable: class noncopyable_base { public: noncopyable_base() {} private: noncopyable_base(const noncopyable_base &); noncopyable_base &operator=(const noncopyable_base &); }; class noncopyable : private noncopyable_base { public: noncopyable() : x_(0) {} noncopyable(int x) : x_(x) {} private: int x_; }; and a template that uses value initialization so that the value will get a known value even when the type is POD: template <class T> void doit() { T t = T(); ... } and trying to use those together: doit<noncopyable>(); This works fine on msvc as of VC++ 9.0 but fails on every version of g++ I tested this with (including version 4.5.0) because the copy constructor is private. Two questions: Which behavior is standards compliant? Any suggestion of how to work around this in gcc (and to be clear, changing that to T t; is not an acceptable solution as this breaks POD types). P.S. I see the same problem with boost::noncopyable.

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• Rails form with a better URL

  - by Sam

  Wow, switching to REST is a different paradigm for sure and is mainly a headache right now. view <% form_tag (businesses_path, :method => "get") do %> <%= select_tag :business_category_id, options_for_select(@business_categories.collect {|bc| [bc.name, bc.id ]}.insert(0, ["All Containers", 0]), which_business_category(@business_category) ), { :onchange => "this.form.submit();"} %> <% end %> controller def index @business_categories = BusinessCategory.find(:all) if params[:business_category_id].to_i != 0 @business_category = BusinessCategory.find(params[:business_category_id]) @businesses = @business_category.businesses else @businesses = Business.all end respond_to do |format| format.html # index.html.erb format.xml { render :xml => @businesses } end end routes map.resources What I want to to is get a better URL than what this form is presenting which is the following: http://localhost:3000/businesses?business_category_id=1 Without REST I would have do something like http://localhost:3000/business/view/bbq bbq as permalink or I would have done http://localhost:300/business_categories/view/bbq and get the business that are associated with the category but I don't really know the best way of doing this. So the two questions are what is the best logic of finding a business by its categories using the latter form and number two how to get that in a pretty URL all through RESTful routes in Rails.

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• return an ArrayList method

  - by Bopeng Liu

  This is a drive method for two other classes. which i posted here http://codereview.stackexchange.com/questions/33148/book-program-with-arraylist I need some help for the private static ArrayList getAuthors(String authors) method. I am kind a beginner. so please help me finish this drive method. or give me some directions. Instruction some of the elements of the allAuthors array contain asterisks “*” between two authors names. The getAuthors method uses this asterisk as a delimiter between names to store them separately in the returned ArrayList of Strings. import java.util.ArrayList; public class LibraryDrive { public static void main(String[] args) { String[] titles = { "The Hobbit", "Acer Dumpling", "A Christmas Carol", "Marley and Me", "Building Java Programs", "Java, How to Program" }; String[] allAuthors = { "Tolkien, J.R.", "Doofus, Robert", "Dickens, Charles", "Remember, SomeoneIdont", "Reges, Stuart*Stepp, Marty", "Deitel, Paul*Deitel, Harvery" }; ArrayList<String> authors = new ArrayList<String>(); ArrayList<Book> books = new ArrayList<Book>(); for (int i = 0; i < titles.length; i++) { authors = getAuthors(allAuthors[i]); Book b = new Book(titles[i], authors); books.add(b); authors.remove(0); } Library lib = new Library(books); System.out.println(lib); lib.sort(); System.out.println(lib); } private static ArrayList<String> getAuthors(String authors) { ArrayList books = new ArrayList<String>(); // need help here. return books; } }

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• How do I left join tables in unidirectional many-to-one in Hibernate?

  - by jbarz

  I'm piggy-backing off of http://stackoverflow.com/questions/2368195/how-to-join-tables-in-unidirectional-many-to-one-condition. If you have two classes: class A { @Id public Long id; } class B { @Id public Long id; @ManyToOne @JoinColumn(name = "parent_id", referencedColumnName = "id") public A parent; } B - A is a many to one relationship. I understand that I could add a Collection of Bs to A however I do not want that association. So my actual question is, Is there an HQL or Criteria way of creating the SQL query: select * from A left join B on (b.parent_id = a.id) This will retrieve all A records with a Cartesian product of each B record that references A and will include A records that have no B referencing them. If you use: from A a, B b where b.a = a then it is an inner join and you do not receive the A records that do not have a B referencing them. I have not found a good way of doing this without two queries so anything less than that would be great. Thanks.

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• Creating a Hello World library function in assembly and calling it from C#

  - by Filip Ekberg

  Let's say we use NASM as they do in this answer: how to write hellow world in assembly under windows. I got a couple of thoughts and questions regarding assembly combined with c# or any other .net languages for that matter. First of all I want to be able to create a library that has the following function HelloWorld that takes this parameter: Name In C# the method signature would looke like this: void HelloWorld(string name) and it would print out something like Hello World from name I've searched around a bit but can't find that much good and clean material for this to get me started. I know some basic assembly from before mostly gasthough. So any pointers in the right direction is very much apprechiated. To sum it up Create a function in ASM ( NASM ) that takes one or more parameters Compile and create a library of the above functionality Include the library in any .net language Call the included library function Bonus features How does one handle returned values? Is it possible to write the ASM-method inline? When creating libraries in assembly or c, you do follow a certain "pre defined" way, the c calling convetion, correct?

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• Routing trouble for RESTful API - Rails

  - by aressidi

  I'm building out an API for web app that I've been working on for some time. I've started with the User model. The user portion of the API will allow remote clients to a) retrieve user data, b) update user information and c) create new users. I've gotten all of this to work, but it doesn't seem like its setup correctly. Here are my questions: Should the API endpoint be users or user? What's the best practice? I have to add the action to the end, which I would expect to be picked up instead by the request type so I don't have to specify it explicitly. How do I get my routes setup properly as not to have to include the method for protected actions? Let me give some examples: Get request for show - want it to work without the "show" curl -u rmbruno:blah http://app.local/api/users/show Put request for update - want it to work without the "update" curl -X put -F 'user[forum_notifications]=true' -u rmbruno:blah http://app.local/api/users/update Create - works with or without 'create' which is what I want for all these actions curl -X post -F 'user[login]=mamafatta' -F 'user[email][email protected]' -F 'user[password]=12345678' http://twye.local/api/users/ How do I structure routes to not require the action name? Isn't that the common way to to RESTful APIs? Here is my route for the API now: map.namespace :api do |route| route.resources :users route.resources :weight end I'm using restful authentication which is handling the http auth in curl. Any guidance on the routes issues and best practice on singular versus plural would be really helpful. Thanks! -A

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• Implementing Model-level caching

  - by Byron

  I was posting some comments in a related question about MVC caching and some questions about actual implementation came up. How does one implement a Model-level cache that works transparently without the developer needing to manually cache, yet still remains efficient? I would keep my caching responsibilities firmly within the model. It is none of the controller's or view's business where the model is getting data. All they care about is that when data is requested, data is provided - this is how the MVC paradigm is supposed to work. (Source: Post by Jarrod) The reason I am skeptical is because caching should usually not be done unless there is a real need, and shouldn't be done for things like search results. So somehow the Model itself has to know whether or not the SELECT statement being issued to it worthy of being cached. Wouldn't the Model have to be astronomically smart, and/or store statistics of what is being most often queried over a long period of time in order to accurately make a decision? And wouldn't the overhead of all this make the caching useless anyway? Also, how would you uniquely identify a query from another query (or more accurately, a resultset from another resultset)? What about if you're using prepared statements, with only the parameters changing according to user input? Another poster said this: I would suggest using the md5 hash of your query combined with a serialized version of your input arguments. This would require twice the number of serialization options. I was under the impression that serialization was quite expensive, and for large inputs this might be even worse than just re-querying. And is the minuscule chance of collision worth worrying about? Conceptually, caching in the Model seems like a good idea to me, but it seems in practicality the developer should have direct control over caching and write it into the controller. Thoughts/ideas? Edit: I'm using PHP and MySQL if that helps to narrow your focus.

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• debugging scaffolding contingent upon degbugging boolean (java)

  - by David

  Recently i've found myself writing a lot of methods with what i can only think to call debugging scaffolding. Here's an example: public static void printArray (String[] array, boolean bug) { for (int i = 0; i<array.lenght; i++) { if (bug) System.out.print (i) ; //this line is what i'm calling the debugging scaffolding i guess. System.out.println(array[i]) ; } } in this method if i set bug to true, wherever its being called from maybe by some kind of user imput, then i get the special debugging text to let me know what index the string being printed as at just in case i needed to know for the sake of my debugging (pretend a state of affairs exists where its helpful). All of my questions more or less boil down to the question: is this a good idea? but with a tad bit more objectivity: Is this an effective way to test my methods and debug them? i mean effective in terms of efficiency and not messing up my code. Is it acceptable to leave the if (bug) stuff ; code in place after i've got my method up and working? (if a definition of "acceptability" is needed to make this question objective then use "is not a matter of programing controversy such as ommiting brackets in an if(boolean) with only one line after it, though if you've got something better go ahead and use your definition i won't mind) Is there a more effective way to accomplish the gole of making debugging easier than what i'm doing? Anything you know i mean to ask but that i have forgotten too (as much information as makes sense is appreciated).

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• Understanding Domain Driven Design

  - by Nihilist

  Hi I have been trying to understand DDD for few weeks now. Its very confusing. I dont understand how I organise my projects. I have lot of questions on UnitOfWork, Repository, Associations and the list goes on... Lets take a simple example. Album and Tracks. Album: AlbumId, Name, ListOf Tracks Tracks: TrackId, Name Question1: Should i expose Tracks as a IList/IEnumerabe property on Album ? If that how do i add an album ? OR should i expose a ReadOnlyCollection of Tracks and expose a AddTrack method? Question2: How do i load Tracks for Album [assuming lazy loading]? should the getter check for null and then use a repository to load the tracks if need be? Question3: How do we organise the assemblies. Like what does each assembly have? Model.dll - does it only have the domain entities? Where do the repositories go? Interfaces and implementations both. Can i define IAlbumRepository in Model.dll? Infrastructure.dll : what shold this have? Question4: Where is unit of work defined? How do repository and unit of work communicate? [ or should they ] for example. if i need to add multiple tracks to album, again should this be defined as AddTrack on Album OR should there a method in the repository? Regardless of where the method is, how do I implement unit of work here? Question5: Should the UI use Infrastructure..dll or should there be ServiceLayer? Do my quesitons make sense? Regards

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• Cassandra hot keyspace structure change

  - by Pierre

  Hello. I'm currently running a 12-node Cassandra cluster storing 4TB of data, with a replication factor set to 3. For the needs of an application update, we need to change the configuration of our keyspace, and we'd like to avoid any downtime if possible. I read on a mailing list that the best way to do it is to: Kill cassandra process on one server of the cluster Start it again, wait for the commit log to be written on the disk, and kill it again Make the modifications in the storage.xml file Rename or delete the files in the data directories according to the changes we made Start cassandra Goto 1 with next server on the list My questions would be: Did I understand the process well? Is there any risk of data corruption? During the process, there will be servers with different versions of the storage.xml file in the same cluser, same keyspace. Is it a problem? Same question as above if we not only add, rename and remove ColumnFamilies, but if we change the CompareWith parameter / transform an existing column family into a super one. Or do we need to change the name? Thank you for your answers. It's the first time I'll do this, and I'm a little bit scared.

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• why won't Eclipse use the compiler I specify for my project?

  - by codeman73

  I'm using Eclipse 3.3. In my project, I've set the compiler compliance level to 5.0 In the build path for the project. I've added the Java 1.5 JDK in the Installed JREs section and am referencing that System Library in my project build path. However, I'm getting compile errors for a class that implements PreparedStatement for not implementing abstract methods that only exist in Java 1.6 PreparedStatement. Specifically, the methods setAsciiStream(int, InputStream, long) and setAsciiStream(int, InputStream) Strangely enough, it worked when we were compiling it against Java 1.4, which it was originally written for. We added the JREs for Java 1.4 and referenced that system library in the project, and set the project's compiler level to 1.4, and it works fine. But when I do the same changes to try to point to Java 5.0, it instead uses Java 6. Any ideas why? I wrote a similar question earlier, here: http://stackoverflow.com/questions/2540548/how-do-i-get-eclipse-to-use-a-different-compiler-version-for-java I know how you're supposed to choose a different compiler but it seems Eclipse isn't taking it. It seems to be defaulting to Java 6, even though I have deleted all Java 6 JDKs and JREs that I could find. I've also updated the -vm option in my eclipse.ini to point to the Java5 JDK.

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• How do I Data-Bind dual DateTimePicker to a single DateTime object

  - by S.C. Madsen

  Hi, I have a simple form, with two DateTimePicker-controls: One for date, and one for time. The thing is these two controls are supposed to represent a single point in time. Hence I would like to "Bind" them to a single DateTime property on my form (for simplicity). I did the following: // Start is a DateTime property on the form _StartDate.DataBindings.Add("Value", this, "Start"); _StartTime.DataBindings.Add("Value", this, "Start"); But hooking into "ValueChanged" event, yields mixed results... Sometimes I get exactly what I want, sometimes the updates of the property are "sluggish". I figured this way of splitting into two DateTimePicker's was fairly common. So how to do it? Update: There is possibly multiple questions in there: How do I bind a DateTimePicker (Format: Date) to a DateTime Property on a form? Then, how do I bind yet another DateTimePicker (Format: Time) to the same property? I'm using Visual Studio Express 2008 (.NET 3.5), and I seemingly get ValueChanged events from the DateTimePickers before the value is changed?

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