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• Obtain all keys of a Neo4j index

  - by MattiSG

  I have a Neo4j database whose content is generated dynamically from a big dataset. All “entry points” nodes are indexed on a named index (IndexManager.forNodes(…)). I can therefore look up a particular “entry point” node. However, I would now like to enumerate all those specific nodes, but I can't know on which key they were indexed. Is there any way to enumerate all keys of a Neo4j Index? If not, what would be the best way to store those keys, a data type that is eminently non-graph-oriented? UPDATE (thanks for asking details :) ): the list would be more than 2 million entries. The main use case would be to never update it after an initialization step, but other use cases might need it, so it has to be somewhat scalable. Also, I would really prefer avoiding killing my current resilience abilities, so storing all keys at once, as opposed to adding them incrementally, would be a last-resort solution.

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• Application wide messaging... without singletons?

  - by StormianRootSolver

  So, I want to go for a more Singleton - less design in the future. However, there seem to be a lot of tasks in an application that can't be done in meaningful way without singletons. I call them "application wide services", but they also fall into the same category as the cross cutting concerns, which I usually fix via AOP. Lets take an example: I want an application wide message queue that dispatches messages to components, every component can subscribe and publish there, it's a very nice multicast thing. The message queue and dispatching system are usually a (rather short) singleton class, which is very easy to implement in, say, C#. You can even use double dispatching and utilize message type metadata and the like, it's all so easy to do, it's almost trivial. However, having singletons is not really "object oriented design" (it introduces global variables) and it makes testing harder. Do you have any ideas? I'm asking this question because I'm willing to learn more about this topic, a LOT more. :-)

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• Serious problem with WCF, GridViews, Callbacks and ExecuteReaders exceptions.

  - by barjed

  Hi, I have this problem that is driving me insane. I have a project to deliver before Thursday. Basically an app consiting of three components that communicate with each other in WCF. I have one console app and one Windows Forms app. The console app is a server that's connected to the database. You can add records to it via the Windows Forms client that connectes with the server through the WCF. The code for the client: namespace BankAdministratorClient { [CallbackBehavior(ConcurrencyMode = ConcurrencyMode.Single, UseSynchronizationContext = false)] public partial class Form1 : Form, BankServverReference.BankServerCallback { private BankServverReference.BankServerClient server = null; private SynchronizationContext interfaceContext = null; public Form1() { InitializeComponent(); interfaceContext = SynchronizationContext.Current; server = new BankServverReference.BankServerClient(new InstanceContext(this), "TcpBinding"); server.Open(); server.Subscribe(); refreshGridView(""); } public void refreshClients(string s) { SendOrPostCallback callback = delegate(object state) { refreshGridView(s); }; interfaceContext.Post(callback, s); } public void refreshGridView(string s) { try { userGrid.DataSource = server.refreshDatabaseConnection().Tables[0]; } catch (Exception ex) { MessageBox.Show(ex.ToString()); } } private void buttonAdd_Click(object sender, EventArgs e) { server.addNewAccount(Int32.Parse(inputPIN.Text), Int32.Parse(inputBalance.Text)); } private void Form1_FormClosing(object sender, FormClosingEventArgs e) { try { server.Unsubscribe(); server.Close(); }catch{} } } } The code for the server: namespace SSRfinal_tcp { class Program { static void Main(string[] args) { Console.WriteLine(MessageHandler.dataStamp("The server is starting up")); using (ServiceHost server = new ServiceHost(typeof(BankServer))) { server.Open(); Console.WriteLine(MessageHandler.dataStamp("The server is running")); Console.ReadKey(); } } } [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Single, InstanceContextMode = InstanceContextMode.PerCall, IncludeExceptionDetailInFaults = true)] public class BankServer : IBankServerService { private static DatabaseLINQConnectionDataContext database = new DatabaseLINQConnectionDataContext(); private static List<IBankServerServiceCallback> subscribers = new List<IBankServerServiceCallback>(); public void Subscribe() { try { IBankServerServiceCallback callback = OperationContext.Current.GetCallbackChannel<IBankServerServiceCallback>(); if (!subscribers.Contains(callback)) subscribers.Add(callback); Console.WriteLine(MessageHandler.dataStamp("A new Bank Administrator has connected")); } catch { Console.WriteLine(MessageHandler.dataStamp("A Bank Administrator has failed to connect")); } } public void Unsubscribe() { try { IBankServerServiceCallback callback = OperationContext.Current.GetCallbackChannel<IBankServerServiceCallback>(); if (subscribers.Contains(callback)) subscribers.Remove(callback); Console.WriteLine(MessageHandler.dataStamp("A Bank Administrator has been signed out from the connection list")); } catch { Console.WriteLine(MessageHandler.dataStamp("A Bank Administrator has failed to sign out from the connection list")); } } public DataSet refreshDatabaseConnection() { var q = from a in database.GetTable<Account>() select a; DataTable dt = q.toTable(rec => new object[] { q }); DataSet data = new DataSet(); data.Tables.Add(dt); Console.WriteLine(MessageHandler.dataStamp("A Bank Administrator has requested a database data listing refresh")); return data; } public void addNewAccount(int pin, int balance) { Account acc = new Account() { PIN = pin, Balance = balance, IsApproved = false }; database.Accounts.InsertOnSubmit(acc); database.SubmitChanges(); database.addNewAccount(pin, balance, false); subscribers.ForEach(delegate(IBankServerServiceCallback callback) { callback.refreshClients("New operation is pending approval."); }); } } } This is really simple and it works for a single window. However, when you open multiple instances of the client window and try to add a new record, the windows that is performing the insert operation crashes with the ExecuteReader error and the " requires an open and available connection. the connection's current state is connecting" bla bla stuff. I have no idea what's going on. Please advise.

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• Class works without declaring variables?

  - by Maxim Droy

  I'm learned php as functional and procedure language. Right now try to start learn objective-oriented and got an important question. I have code: class car { function set_car($model) { $this->model = $model; } function check_model() { if($this->model == "Mercedes") echo "Good car"; } } $mycar = new car; $mycar->set_car("Mercedes"); echo $mycar->check_model(); Why it does work without declaration of $model? var $model; in the begin? Because in php works "auto-declaration" for any variables? I'm stuck

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• What is an instance of a field called?

  - by waxwing

  This might be an odd question, but it has actually caused me some headache. In Object oriented programming, there are accepted names for key concepts. In our model, we have classes with methods and fields. Now, going to the data world: An instance of a class is called an object. An instance of a field is called... what? A value? Isn't the term value a little broad for this? I have been offered "property" as well, but isn't property also part of the model and not the data? (This is not purely academic, I am actually coding these concepts.)

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• list(of byte) to Picturebox

  - by michael

  I have a jpeg file that is being held as a list(of Byte) Currently I have code that I can use to load and save the jpeg file as either a binary (.jpeg) or a csv of bytes (asadsda.csv). I would like to be able to take the list(of Byte) and convert it directly to a Picturebox without saving it to disk and then loading it to the picturebox. If you are curious, the reason I get the picture file as a list of bytes is because it gets transfered over serial via an industrial byte oriented protocol as just a bunch of bytes. I am using VB.net, but C# example is fine too.

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• For what purposes have YOU used T4?

  - by Chris Melinn

  T4 has existed for several years in Visual Studio, but doesn't get a lot of attention. However, for those that know it, there seems to be some very creative and useful purposes. I am researching some different ways that T4 is used, and I would appreciate to hear how YOU may have used it for real life scenarios. I am primarily interested in non-standard and creative uses. Some interesting examples: Phil Haack uses T4 to create static CSS files from .less To Generate WPF and Silverlight Dependency Properties using T4 Templates Note: I realize this is a discussion-oriented question, but the answers could be helpful to others. I have tagged it as subjective and also marked as "community wiki", so please allow the question to remain open. Thanks!

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• rails respond_to and various forms of html responses

  - by lukewendling

  I often use respond_to do |format| ... end in Rails for my Restful actions, but I don't know what the ideal solution is for handling various forms of, say, html responses. For instance, view1 that calls action A might expect back html with a list of widgets wrapped in a UL tag, while view2 expects the same list of widgets wrapped in a table. How does one Restfully express that not only do I want back an html formatted response, but I want it wrapped in a table, or in a UL, OL, options, or some other common list-oriented html tag?

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• How to structure a bigger/complicated project?

  - by Per

  Hello, I'm creating this (big?) project in high school where I'm programming the game Shithead (card game) (so that two people can play against eachother). I'll use mostly PHP, MySQL, JavaScript and Ajax. But I have never made a project like this before. I have only made like CMS-systems and so on. Do you guys have any tips on how I should structure this project? I'm also not so used to Object-oriented programming, but I guess I should consider this. Should I, for example, make a class for the cards? I'm very thankful for any tips or good links!

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• Class views in Django

  - by Sebastjan Trepca

  Django view points to a function, which can be a problem if you want to change only a bit of functionality. Yes, I could have million keyword arguments and even more if statements in the function, but I was thinking more of an object oriented approach. For example, I have a page that displays a user. This page is very similar to page that displays a group, but it's still not so similar to just use another data model. Group also has members etc... One way would be to point views to class methods and then extend that class. Has anyone tried this approach or has any other idea?

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• Right programing language for developing application for Mac

  - by drasto

  I'm planing to buy Mac. I would like to be able to develop GUI aplication for Mac as well. Currently I develop in C# using VisualStudio as IDE. I also know Java and I'm familiar with NetBeans IDE. Application created in both of this languages can run on Mac (as can NetBeans IDE) but I was told that neither C# nor Java is recomended for MacOS X development. So what language is recomended for MacOS X development ? I guess there is some recomodation from Apple for the developers ? I would prefer Object-oriented easy-to-use programing language (nothing like C) with good IDE that supports GUI creating (GUI designer). Thank you for answers

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• Do I must expose the aggregate children as public properties to implement the Persistence ignorance?

  - by xuehua

  Hi all, I'm very glad that i found this website recently, I've learned a lot from here. I'm from China, and my English is not so good. But i will try to express myself what i want to say. Recently, I've started learning about Domain Driven Design, and I'm very interested about it. And I plan to develop a Forum website using DDD. After reading lots of threads from here, I understood that persistence ignorance is a good practice. Currently, I have two questions about what I'm thinking for a long time. Should the domain object interact with repository to get/save data? If the domain object doesn't use repository, then how does the Infrastructure layer (like unit of work) know which domain object is new/modified/removed? For the second question. There's an example code: Suppose i have a user class: public class User { public Guid Id { get; set; } public string UserName { get; set; } public string NickName { get; set; } /// <summary> /// A Roles collection which represents the current user's owned roles. /// But here i don't want to use the public property to expose it. /// Instead, i use the below methods to implement. /// </summary> //public IList<Role> Roles { get; set; } private List<Role> roles = new List<Role>(); public IList<Role> GetRoles() { return roles; } public void AddRole(Role role) { roles.Add(role); } public void RemoveRole(Role role) { roles.Remove(role); } } Based on the above User class, suppose i get an user from the IUserRepository, and add an Role for it. IUserRepository userRepository; User user = userRepository.Get(Guid.NewGuid()); user.AddRole(new Role() { Name = "Administrator" }); In this case, i don't know how does the repository or unit of work can know that user has a new role? I think, a real persistence ignorance ORM framework should support POCO, and any changes occurs on the POCO itself, the persistence framework should know automatically. Even if change the object status through the method(AddRole, RemoveRole) like the above example. I know a lot of ORM can automatically persistent the changes if i use the Roles property, but sometimes i don't like this way because of the performance reason. Could anyone give me some ideas for this? Thanks. This is my first question on this site. I hope my English can be understood. Any answers will be very appreciated.

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• jQuery .find() doesn't return data in IE but does in Firefox and Chrome

  - by Steve Hiner

  I helped a friend out by doing a little web work for him. Part of what he needed was an easy way to change a couple pieces of text on his site. Rather than having him edit the HTML I decided to provide an XML file with the messages in it and I used jQuery to pull them out of the file and insert them into the page. It works great... In Firefox and Chrome, not so great in IE7. I was hoping one of you could tell me why. I did a fair but of googling but couldn't find what I'm looking for. Here's the XML: <?xml version="1.0" encoding="utf-8" ?> <messages> <message type="HeaderMessage"> This message is put up in the header area. </message> <message type="FooterMessage"> This message is put in the lower left cell. </message> </messages> And here's my jQuery call: <script type="text/javascript"> $(document).ready(function() { $.get('messages.xml', function(d) { //I have confirmed that it gets to here in IE //and it has the xml loaded. //alert(d); gives me a message box with the xml text in it //alert($(d).find('message')); gives me "[object Object]" //alert($(d).find('message')[0]); gives me "undefined" //alert($(d).find('message').Length); gives me "undefined" $(d).find('message').each(function() { //But it never gets to here in IE var $msg = $(this); var type = $msg.attr("type"); var message = $msg.text(); switch (type) { case "HeaderMessage": $("#HeaderMessageDiv").html(message); break; case "FooterMessage": $("#footermessagecell").html(message); break; default: } }); }); }); </script> Is there something I need to do differently in IE? Based on the message box with [object Object] I'm assumed that .find was working in IE but since I can't index into the array with [0] or check it's Length I'm guessing that means .find isn't returning any results. Any reason why that would work perfectly in Firefox and Chrome but fail in IE? I'm a total newbie with jQuery so I hope I haven't just done something stupid. That code above was scraped out of a forum and modified to suit my needs. Since jQuery is cross-platform I figured I wouldn't have to deal with this mess. Edit: I've found that if I load the page in Visual Studio 2008 and run it then it will work in IE. So it turns out it always works when run through the development web server. Now I'm thinking IE just doesn't like doing .find in XML loaded off of my local drive so maybe when this is on an actual web server it will work OK. I have confirmed that it works fine when browsed from a web server. Must be a peculiarity with IE. I'm guessing it's because the web server sets the mime type for the xml data file transfer and without that IE doesn't parse the xml correctly.

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• Use of class definitions inside a method in Java

  - by Bragaadeesh

  Hi public class TestClass { public static void main(String[] args) { TestClass t = new TestClass(); } private static void testMethod(){ class TestMethodClass{ int a; int b; int c; } TestMethodClass testMethodClass = new TestMethodClass(); } } I found out that the above piece of code is perfectly legal in Java. I have the following questions. What is the use of ever having a class definition inside a method? Will a class file be generated for TestMethodClass Its hard for me to imagine this concept in an Object Oriented manner. Having a class definition inside a behavior. Probably can someone tell me with equivalent real world examples. Thanks

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• Is there any Application Server Frameworks for other languages/platforms than JavaEE and .NET?

  - by Jonas

  I'm a CS student and has rare experience from the enterprise software industry. When I'm reading about enterprise software platforms, I mostly read about these two: Java Enterprise Edition, JavaEE .NET and Windows Communication Foundation By "enterprise software platforms" I mean frameworks and application servers with support for the same characteristics as J2EE and WCF has: [JavaEE] provide functionality to deploy fault-tolerant, distributed, multi-tier Java software, based largely on modular components running on an application server. WCF is designed in accordance with service oriented architecture principles to support distributed computing where services are consumed by consumers. Clients can consume multiple services and services can be consumed by multiple clients. Services are loosely coupled to each other. Is there any alternatives to these two "enterprise software platforms"? Isn't any other programming languages used in a bigger rate for this problem area? I.e Why isn't there any popular application servers for C++/Qt?

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• Will PHP script running on top of Apache be faster than C# stand alloun programm doing same thing (s

  - by Ole Jak

  I mean PHP scripts on Apache are oriented for many users to use tham at the same time. So will 1000 requests which came at the (relativly) same time be fully responsed faster than C# .Net programm perfoming algorithm 1000 times in while loop? So we input same data, we perform same algorithm, which is written in a wary same way (respecting language diferencis ofcourse), outputing same data (lat us say saving it to file for tham to be relativly equal) Who will be faster on some 1000 times of performing O(NN) algorithm, in which case (if it is possible) one will owerrun another?

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• Indexing an image in-between already made content

  - by Christophersson

  I have a pre-code page coded as follows: <div id="linearBg"> <div id="wrapper"> <div class="logo"></div> <div class="navigation"></div> <div class="video"></div> <div class="content"></div> </div> </div> Where linearBg is a gradient background, the back board of the website. Wrapper is the container for the inner div's, and the rest are content oriented. So i've already implemented this with styles and all sorts, but the thing is I want to add: <div class="watermark"></div> underneath/behind both the content and video div, sort of like a reverse watermark, I've tried z-indexing but i'm not an expert. Could you guide me on to do make this possible? Thanks in advance

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• RESTful web service, PUTting an unnamed resource?

  - by James L

  I have a back-end service that creates unique identifiers for resources. The general idea is that resources are saved and versioned, so you can perform: GET http://service/sales/targets/7818181919/latest or GET http://service/sales/targets/7818181919/4 for version 4, and so on. My question is about the most correct way to upload these resources in the first place. How about: PUT http://service/sales/targets/ returning 303 See other /service/sales/targets/ It seems a little wrong as you should PUT and GET from exactly the same place using a resource-oriented interface, but I can't think of a better option. Any ideas?

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• Is the FoldLeft function available in R?

  - by JSmaga

  Hi, I would like to know if there is an implementation of the foldLeft function (and foldRight?) in R. The language is supposed to be "rather" functional oriented and hence I think there should be something like this, but I could not find it in the documentation. To me, foldLeft function applies on a list and has the following signature: foldLeft[B](z : B)(f : (B, A) => B) : B It is supposed to return the following result: f(... (f(f(z, a0), a1) ...), an) if the list is [a0, a1, ..., an]. (I use the definition of the Scala List API) Does anybody know if such a function exists in R?

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• Choosing an alternative ( visual basic) high level programming language

  - by user370244

  I used to be visual basic 6 programmer, i was pleased with visual basic : it is high level language that do stuff fast,easy to learn, easy to do stuff in,you can drag and drop stuff to the form and write your code,it is simply amazing.however microsoft buried VB6 and pointed us to VB.NET which is so different that it is not the old VB anymore.I didn't like what microsoft did and would like to look somewhere AWAY from microsoft and from any other proprietary language . I would like to look into a similar language that is easy,cross platform (windows / Linux), object oriented, visual design, non proprietary and compile (for some guarding against reverse engineering). i am freelancer so the choice is entirely mine,i don't care about performance of programs, the time taken to develop a given programs is much more important. desktop / database / GUI /networking programming is what i am looking for. so any such language offered by our open source community ? thank you so much

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• In PHP: How to call a $variable inside one function that was defined previously inside another funct

  - by Sam

  I'm just starting with Object Oriented PHP and I have the following issue: I have a class that contains a function that contains a certain script. I need to call a variable located in that script within another function further down the same class. For example: class helloWorld { function sayHello() { echo "Hello"; $var = "World"; } function sayWorld() { echo $var; } } in the above example I want to call $var which is a variable that was defined inside a previous function. This doesn't work though, so how can I do this?

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• Fastest way to convert a binary file to SQLite database

  - by chown

  I've some binary files and I'm looking for a way to convert each of those files to a SQLite database. I've already tried C# but the performance is too slow. I'm seeking an advice on how and what programming language should be the best to perform this kind of conversion. Though I prefer any Object Oriented Language more (like C#, Java etc), I'm open for any programming language that boosts up the conversion. I don't need a GUI frontend for the conversion, running the script/program from console is okay. Thanks in advance

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• should a student be diversifying or mastering programming languages?

  - by Max Link

  As the question states, is it better if a student diversifies or explores when learning programming languages or should they focus only on 2-3 languages and really get to know them well? Example of what I mean by diversifying: Functional -> Scheme Procedural -> C Object Oriented -> Java Dynamic or scripting -> Python Other -> C++ I have a few breaks in between semesters sometimes (up to 3 months) and I'm thinking of either learning a new language or "master" those that I know right now. Which would benefit me in the future? I know some(about 3 months of self studying each) Java, C, and C++ already . If I'm not mistaken, where I live, the industry is heavy on Java, C++, and C#.

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• Is it possible to Serialize and Deserialize objects in C++?

  - by GK

  As we know c++ is also an Object Oriented Programming language where most the things are objects like java. So wanted to know is the Serialize and deserializ features are available in c++ as well as we do it in java? If yes how it can be achieved? In java We use Serializable Interface to say that this type of object can be serialized and deserialized. So in c++ how? And out of curiosity is it same in c# as in java?

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• Private vs. Public members in practice (how important is encapsulation?)

  - by Asmor

  One of the biggest advantages of object-oriented programming is encapsulation, and one of the "truths" we've (or, at least, I've) been taught is that members should always be made private and made available via accessor and mutator methods, thus ensuring the ability to verify and validate the changes. I'm curious, though, how important this really is in practice. In particular, if you've got a more complicated member (such as a collection), it can be very tempting to just make it public rather than make a bunch of methods to get the collection's keys, add/remove items from the collection, etc. Do you follow the rule in general? Does your answer change depending on whether it's code written for yourself vs. to be used by others? Are there more subtle reasons I'm missing for this obfuscation?

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