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• Avoiding mass propagation of properties and events for exposure to ViewModels.

  - by firoso

  I have an MVVM application I am developing that is to the point where I'm ready to start putting together a user interface (my client code is largely functional) I'm now running into the issue that I'm trying to get my application data to where I need it so that it can be consumed by the view model and then bound to the view. Unfortunately, it seems that I've either got a few structural oversights, or I'm just going to have to face the reality that I need to be propogating events and raising excessive amounts of errors to notify view models that thier properties have changed. Let me go into some examples of my issue: I have a class "Unit" contained in a class "Test", contained in a class "Session" contained in a class "TestManager" which is contained in "TestDataModel" which is utilized by "TestViewModel" which is databound to by my "TestView" .... WHOA. Now, consider that Unit (the bottom of the heiarchy) has a property called "Results" that is updated periodically, I want to expose that to my viewmodel and then databind it to my view, trouble is, the only way I can really think to do this is to perpetuate events WAY up a chain that say "I've been updated!" and then request the new value... This seems like an aweful way to do this. Alternatively, I could register a static event and raise it, and have the appropriate "Unit view model" grab the event and request the update. This SEEMS better... but... static events? Is that a taboo idea? Also, having an expression like: TestDataModel.TestManager.Session.Test.Unit.Results[i] Seems REALLY gross to have on a View Model. I know this all reeks of a bad design issue, but I can't figure out what I did wrong? Should I be using more singleton/container controlled lifetimes type objects? Register object instances with static helper containers? Obviously these are hard questions to answer without being intimate with the existing structure, but if you've run into situations like this, what did you do to refactor? Should I just live with this, add mass events, and propogate them?

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• Inserting default "admin" user into database during Rails App startup

  - by gbc

  I'm building my first real rails application for a little in-house task. Most of the application tasks require authentication/authorization. The first time the app starts up (or starts with a wiped db), I'd like the process to be: User logs into the admin panel using "admin" & "admin" for authentication info. User navigates to admin credentials editing page and changes name and password to something safer so that "admin" & "admin" is no longer a valid login. To achieve this result, I'd like to stuff a default username & password combination into the database on if the application starts up and detects that there are no user credentials in the 'users' table. For example: if User.count == 0 User.create(:name => "admin", :password => "admin") end However, I'm unsure where to place that code. I tried adding an initializer script in the config/initializers, but the error I received appeared to indicate that the model classes weren't yet loaded into the application. So I'm curious to know at what point I can hook into the application startup cycle and insert data into the database through ActiveRecord before requests are dispatched.

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• How can I evaluate the connectedness of my nodes?

  - by Travis Leleu

  I've got a space that has nodes that are all interconnected, based on a "similarity score". I would like to determine how "connected" a node is with the others. My purpose is to find nodes that are poorly connected to make sure that the backlink from the other node is prioritized. Perhaps an example would help. I've got a web page that links to my other pages based on a similarity score. Suppose I have the pages: A, B, C, ... A has a backlink from every other page, so it's very well connected. It also has links to all my other pages (each line in the graph is essentially bidirectional). B only has 1 backlink, from A. C has a link from A and D. I would like to make sure that the A-B link is prioritized over the A-C link (even if the similarity score between C and A is higher than B and A). In short, I would like to evaluate which nodes are least and best connected, so that I can mangle the results to my means. I believe this is Graph Connectedness, but I'm at a loss to develop a (simple) algorithm that will help me here. Simply counting the backlinks to a node may be a starting point -- but then how do I take the next step, which is to properly weight the links on the original node (A, in the example above)?

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• Create Session Variable from different datasources?

  - by Szafranamn

  Currently I am developing a dynamic website using Dreamweaver cs5 with ColdFusion 9 and using Access to create my databases along with QuickBooks and QODBC to create database. I have established a login session variable stemming from the login page. This session variable is being drawn from one Datasource "Access" Table "Logininfo" Field "FullName" but I wanted to create another session variable either at this point or further into the member's page to use in a query sequence. This session variable would stem from another Datasoucre "QBs" Table "Invoice" Field "CustomerRefFullName" which is generated through Quickbooks and QODBC. I am not sure if this is possible but if it is how do I do it. I want to do this so I can query the Invoice database to upload the customer's Invoices unique to them onto their page. So it would have to be related to their login credentials. If there is another better route to take I would greatly appreciate the advice. Below is the login code if there is additional information needed let me know. This is my current thinking/plan to do what I wish to intend hence the need to create the session variable: I have another Datasource "QBs" with a Table "Invoice" when I create another webpage for the customer to see their invoice I need to create a recordset that accesses that Table. In order to do so I think the best way would some home convert the session.FullName (which came from Access Datasource, Logininfor Table) into a session.CustomerRefFullName (which would have to come from (Datasource: QBs Table: Invoice Field: CustomerRefFullName) that way I could set the query WHERE CustomerRefFullName and have each logged in user see their specific Invoices. So is there a way to turn the session variable off one datasource/table into a different sessionvariable off a new datasource/table even if it is unique just to that page??? <cfif IsDefined("FORM.username")> SELECT FullName, Username,Password,AccessLevels FROM Logininfo WHERE Username= AND Password=

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• Titanium TableViewRow classname with custom rows

  - by pancake

  I would like to know in what way the 'className' property of a Ti.UI.TableViewRow helps when creating custom rows. For example, I populate a tableview with custom rows in the following way: function populateTableView(tableView, data) { var rows = []; var row; var title, image; var i; for (i = 0; i < data.length; i++) { title = Ti.UI.createLabel({ text : data[i].title, width : 100, height: 30, top: 5, left: 25 }); image = Ti.UI.createImage({ image : 'some_image.png', width: 30, height: 30, top: 5, left: 5 }); /* and, like, 5+ more views or whatever */ row = Ti.UI.createTableViewRow(); row.add(titleLabel); row.add(image); rows.push(row); } tableView.setData(rows); } Of course, this example of a "custom" row is easily created using the standard title and image properties of the TableViewRow, but that isn't the point. How is the allocation of new labels, image views and other child views of a table view prevented in favour of their reuse? I know in iOS this is achieved by using the method -[UITableView dequeueReusableCellWithIdentifier:] to fetch a row object from a 'reservoir' (so 'className' is 'identifier' here) that isn't currently being used for displaying data, but already has the needed child views laid out correctly in it, thus only requiring to update the data contained within (text, image data, etc). As this system is so unbelievably simple, I have a lot of trouble believing the method employed by the Titanium API does not support this. After reading through the API and searching the web, I do however suspect this is the case. The 'className' property is recommended as an easy way to make table views more efficient in Titanium, but its relation to custom table view rows is not explained in any way. If anyone could clarify this matter for me, I would be very grateful.

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• Using MATLAB's plotting features as an interactive part of a Fortran program

  - by ldigas

  Although many of you will have a decent idea of what I'm aiming at, just from reading the title -- allow me a simple introduction still. I have a Fortran program - it consists of a program, some internal subroutines, 7 modules with its own procedures, and ... uhmm, that's it. Without going into much detail, for I don't think it's necessary at this point, what would be the easiest way to use MATLAB's plotting features (mainly plot(x,y) with some customizations) as an interactive part of my program ? For now I'm using some of my own custom plotting routines (based on HPGL and Calcomp's routines), but just as part of an exercise on my part, I'd like to see where this could go and how would it work (is it even possible what I'm suggesting?). Also, how much effort would it take on my part ? I know this subject has been rather extensively described in many "tutorials" on the net, but for some reason I have trouble finding the really simple yet illustrative introductory ones. So if anyone can post an example or two, simple ones, I'd be really grateful. Or just take me by the hand and guide me through one working example. platform: IVF 11.something :) on Win XP SP2, Matlab 2008b

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• ESXi with software iSCSI

  - by jharley

  Has anyone had any luck using the swiSCSI driver on ESXi? Following the instructions from VMWare.com I get to the point where I have the iSCSI HBA showing up but no LUNs/targets are showing up. The iSCSI target is running on Solaris 10 update 5 and works with other initiators fine. The ESXi initiator (from the logs) sees the targets but just logs in and out of them every 2 - 5 seconds. We're using unauthenticated discovery, and over and over in /var/log/messages I see: iSCSI: bus 0 target 0 trying to establish session 0xb203f90 to portal 0, address 10.1.100.9 port 3260 group 1 iSCSI: bus 0 target 0 establish session 0xb203f90 #4848 to port 0, address 10.1.100.9 port 3260 group 1, alias data/ESXi iSCSI: session 0xb203f90 dropping after receiving unexpected opcode 0x60 iSCSI: session 0xb203f90 to data/ESXi dropped iSCSI: session 0xb203f90 to data/ESXi waiting 2 seconds before next login attempt The only other thing that seems out of wack is that my 'Recent Tasks' pane keeps filling with 'Browse Diagnostic Manager' events and /var/log/vmware/hostd.log is filled with messages like this up to two times per second: [2008-09-19 16:05:57.901 'TaskManager' 196621 info] Task Created: haTask-ha-host-vim.DiagnosticManager.browser-776 [2008-09-19 16:05:57.094 'TaskManager' 196621 info] Task Completed: haTask-ha-host-vim.DiagnosticManager.browser-766 Any help would be appreciated.

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• Managing libraries and imports in a programming language

  - by sub

  I've created an interpreter for a stupid programming language in C++ and the whole core structure is finished (Tokenizer, Parser, Interpreter including Symbol tables, core functions, etc.). Now I have a problem with creating and managing the function libraries for this interpreter (I'll explain what I mean with that later) So currently my core function handler is horrible: // Simplified version myLangResult SystemFunction( name, argc, argv ) { if ( name == "print" ) { if( argc < 1 ) { Error('blah'); } cout << argv[ 0 ]; } else if ( name == "input" ) { if( argc < 1 ) { Error('blah'); } string res; getline( cin, res ); SetVariable( argv[ 0 ], res ); } else if ( name == "exit ) { exit( 0 ); } And now think of each else if being 10 times more complicated and there being 25 more system functions. Unmaintainable, feels horrible, is horrible. So I thought: How to create some sort of libraries that contain all the functions and if they are imported initialize themselves and add their functions to the symbol table of the running interpreter. However this is the point where I don't really know how to go on. What I wanted to achieve is that there is e.g.: an (extern?) string library for my language, e.g.: string, and it is imported from within a program in that language, example: import string myString = "abcde" print string.at( myString, 2 ) # output: c My problems: How to separate the function libs from the core interpreter and load them? How to get all their functions into a list and add it to the symbol table when needed? What I was thinking to do: At the start of the interpreter, as all libraries are compiled with it, every single function calls something like RegisterFunction( string namespace, myLangResult (*functionPtr) ); which adds itself to a list. When import X is then called from within the language, the list built with RegisterFunction is then added to the symbol table. Disadvantages that spring to mind: All libraries are directly in the interpreter core, size grows and it will definitely slow it down.

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• SQL Server race condition issue with range lock

  - by Freek

  I'm implementing a queue in SQL Server (please no discussions about this) and am running into a race condition issue. The T-SQL of interest is the following: set transaction isolation level serializable begin tran declare @RecordId int declare @CurrentTS datetime2 set @CurrentTS=CURRENT_TIMESTAMP select top 1 @RecordId=Id from QueuedImportJobs with (updlock) where Status=@Status and (LeaseTimeout is null or @CurrentTS>LeaseTimeout) order by Id asc if @@ROWCOUNT> 0 begin update QueuedImportJobs set LeaseTimeout = DATEADD(mi,5,@CurrentTS), LeaseTicket=newid() where Id=@RecordId select * from QueuedImportJobs where Id = @RecordId end commit tran RecordId is the PK and there is also an index on Status,LeaseTimeout. What I'm basically doing is select a record of which the lease happens to be expired, while simultaneously updating the lease time with 5 minutes and setting a new lease ticket. So the problem is that I'm getting deadlocks when I run this code in parallel using a couple of threads. I've debugged it up to the point where I found out that the update statement sometimes gets executing twice for the same record. Now, I was under the impression that the with (updlock) should prevent this (it also happens with xlock btw, not with tablockx). So it actually look like there is a RangeS-U and a RangeX-X lock on the same range of records, which ought to be impossible. So what am I missing? I'm thinking it might have something to do with the top 1 clause or that SQL Server does not know that where Id=@RecordId is actually in the locked range? Deadlock graph: Table schema (simplified):

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• Is it "right" to translate error messages?

  - by Iraklis

  This is somehow subjective depending on the target translation language, but bear with me for a sec. I have recently been involved in a translation project. The goal was to translate the strings of an MVC framework to the Greek language. 70% of the language strings of the framework where translated, however 30% where intentionally left out. The decision was that we will not translate error messages aimed towards the developer of the application. The reasoning behind this (in short) was: are aimed towards designers/programmers. Programmers ( and even designers :) ) should have a basic understanding of English, at least enough so they can search on it on Google if they do not know what it means. (racist?) are aimed towards the developer and in a perfect world should not be displayed to the end user of the application as they concern the inner workings of the web application itself. i.e "You must set the database name in your database config file." and perhaps most importantly, they make the life of the developer harder when he tries to get more information/help regarding the error. For example the above error yields 8 results in Google (in quotes), whereas its Greek translation yields exactly 0. I know that this depends on the popularity of the target translation language and the application itself. For example I'm guessing that there are is vast amount of documentation regarding German SAP error messages (i know, i know, SAP IS German, but you get the point), as opposed to Greek Error Messages documentation regarding random application X which has about 500 installations worldwide. So to summarize: When you develop language translation packs for your applications do you translate error messages? Do you only do for predominant languages like English/Spanish/German/French? Or do you live them intact? I'm not looking for the "right" or "correct" answer, I'm looking for a "best-practices" answer, or if this problem is defined in any "official" standard/policy that you have had experience with.

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• [C++][OpenMP] Proper use of "atomic directive" to lock STL container

  - by conradlee

  I have a large number of sets of integers, which I have, in turn, put into a vector of pointers. I need to be able to update these sets of integers in parallel without causing a race condition. More specifically. I am using OpenMP's "parallel for" construct. For dealing with shared resources, OpenMP offers a handy "atomic directive," which allows one to avoid a race condition on a specific piece of memory without using locks. It would be convenient if I could use the "atomic directive" to prevent simultaneous updating to my integer sets, however, I'm not sure whether this is possible. Basically, I want to know whether the following code could lead to a race condition vector< set<int>* > membershipDirectory(numSets, new set<int>); #pragma omp for schedule(guided,expandChunksize) for(int i=0; i<100; i++) { set<int>* sp = membershipDirectory[5]; #pragma omp atomic sp->insert(45); } (Apologies for any syntax errors in the code---I hope you get the point) I have seen a similar example of this for incrementing an integer, but I'm not sure whether it works when working with a pointer to a container as in my case.

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• Getting the time interval between typing characters in a TextBox, in C#

  - by sama

  I have a form that has a TextBox and a Label and I want to get the time of the first character entered in the textbox. Then if the user enters more than ten charcaters, the time between the first charcter entered and the tenth charcter entered is displayed in the label. Can any one help me please? I'm using C# Here is the code but I cannot complete it and I have many things that need to be written but I don't know how to continue. using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; namespace n { public partial class Form1 : Form { int count=0; public Form1() { InitializeComponent(); } private void textBox1_TextChanged(object sender, EventArgs e) { DateTime t1 = new DateTime();// the time when entering the first charcter DateTime t2 = new DateTime(); t2 = System.DateTime.Now - t1; int index = textBox1.SelectionStart; Point p; p = textBox1.GetPositionFromCharIndex(index); Thread t = new Thread(counttext); t.Start(); label1.Text = "t2"; } private int counttext() { while (textBox1.Text.Length < 10) { count++; if (count == 10) return count; } } } }

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• GPL/LGPL-licensed images + iPhone development

  - by cubic1271

  Since the majority of legal links / READMEs I've found when browsing icon sets refer me to the general GPL / LGPL (as opposed to a specialized version of some kind) when I'm looking at license restrictions, I'm having a terrible time trying to figure out what would constitute source code, linking, etc. when it comes to images and / or icons. One specific example: under section 5 of the GPL, modifications must carry notices in the source code. . . how do I do that with an image? I guess I could try to find a few unused bits and encode my modifications in there (steganography, anyone?), but somehow that doesn't seem like what the license is shooting for. There are also other sections in there where I have no idea how to begin to comply with. Thus, I'm really confused. What exactly are the implications of using GPL and / or LGPL licensed images in something that isn't itself GPL'd? Specifically, I'd like to know what using GPL icons in an iPhone application might mean from a legal point of view. It feels like I'm missing something obvious here; any enlightenment / references would be appreciated!

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• Problem with passing vector of pointers to objects to member function of another object

  - by Jamesz

  Hi, I have a vector of pointers to Mouse objects called 'mice'. I'm passing the mice to the cat by reference. vector <Mouse*> mice; Cat * c; c->lookForMouse(&mice); And here's my lookForMouse() member function void Cat::lookForMouse(vector <Mouse*> *mice) { ... } And now to the problem! Within the function above, I can't seem to access my mice. This below will not work mice[i]->isActive(); The error message I receive suggests to use mice[i].isActive(), but this throws an error saying isActive() is not a member of std::vector<_Ty ... This works though... vector <Mouse*> miceCopy = *mice; miceCopy[i]->isActive(); I understand that I shouldn't be creating another vector of mice here, it defeats the whole point of passing it by reference (let me know if I'm wrong)... Why can't I do mice[i]-isActive() What should I be doing? Thanks for your time and help :D James.

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• Omit return type in C++0x

  - by Clinton

  I've recently found myself using the following macro with gcc 4.5 in C++0x mode: #define RETURN(x) -> decltype(x) { return x; } And writing functions like this: template <class T> auto f(T&& x) RETURN (( g(h(std::forward<T>(x))) )) I've been doing this to avoid the inconvenience having to effectively write the function body twice, and having keep changes in the body and the return type in sync (which in my opinion is a disaster waiting to happen). The problem is that this technique only works on one line functions. So when I have something like this (convoluted example): template <class T> auto f(T&& x) -> ... { auto y1 = f(x); auto y2 = h(y1, g1(x)); auto y3 = h(y1, g2(x)); if (y1) { ++y3; } return h2(y2, y3); } Then I have to put something horrible in the return type. Furthermore, whenever I update the function, I'll need to change the return type, and if I don't change it correctly, I'll get a compile error if I'm lucky, or a runtime bug in the worse case. Having to copy and paste changes to two locations and keep them in sync I feel is not good practice. And I can't think of a situation where I'd want an implicit cast on return instead of an explicit cast. Surely there is a way to ask the compiler to deduce this information. What is the point of the compiler keeping it a secret? I thought C++0x was designed so such duplication would not be required.

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• Presenting collection of structures of strings in grid or similar in WPF - Example? Ideas?

  - by Andrew

  Hi, I have a collection of structures. The structure is just some strings. Example public struct ReportLine { public string Name; public string Address; public string Phone; ...// about 10 other strings } I can't change this part. What I want to do is display it in a simple grid or simlar in WPF. My only requirements are: a) need column headers b) rows must alternate in color c) columns big enough to hold largest datum (which is not know until run time) Can someone point me to an example to get me started? Is the GridView the way to go? Or DataGrid? Or perhaps just the grid? I have the book Pro WPF in C# 2008 and it covers binding ListBox's to collections, but the collections always seem to be collections of one field (ex. a collection of 40 names). Here I have a collection (an array in fact) of a structure. How do I setup the databinding? As you can see, I'm new to this and probably would most benefit from a reference to an article. I've found articles covering collections of 1 field, but no examples covering binding to an array of structures. Also, my intitial research indicates c) can't be easily done, if you demand that the column is big enough for all the data in that column, not just the visible data. Thanks, dave

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• Pointing class property to another class with vectors

  - by jmclem

  I've got a simple class, and another class that has a property that points to the first class: #include <iostream> #include <vector> using namespace std; class first{ public: int var1; }; class second{ public: first* classvar; }; Then, i've got a void that's supposed to point "classvar" to the intended iteration of the class "first". void fill(vector<second>& sec, vector<first>& fir){ sec[0].classvar = &fir[0]; } Finally the main(). Create and fill a vector of class "first", create "second" vector, and run the fill function. int main(){ vector<first> a(1); a[0].var1 = 1000; vector<second> b(1); fill(b, a); cout << b[0].classvar.var1 << '\n'; system("PAUSE"); return 0; } This gives me the following error: 1>c:\...\main.cpp(29) : error C2228: left of '.var1' must have class/struct/union 1> type is 'first *' And I can't figure out why it reads the "classvar" as the whole vector instead of just the single instance. Should I do this cout << b[0].classvar[0].var1 << '\n'; it reads perfectly. Can anyone figure out the problem? Thanks in advance

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• Is it possible to Kick off a java process under Windows Service with C#?

  - by Wing C. Chen

  I would like to wrap a java program into a windows service with C# using System.ServiceProcess.ServiceBase. So I came up with the following code: /// <summary> /// The main entry point for the application. /// </summary> static void Main() { System.ServiceProcess.ServiceBase.Run(new JavaLauncher()); } protected override void OnStart(string[] args) { Thread _thread; _thread = new Thread(StartService); _thread.Start(); base.OnStart(args); } protected override void OnStop() { Thread _thread; _thread = new Thread(StopService); _thread.Start(); base.OnStop(); } static public void StartService() { System.Diagnostics.Process proc = new System.Diagnostics.Process(); proc.EnableRaisingEvents = false; proc.StartInfo.FileName = "javaw"; proc.StartInfo.Arguments = config.generateLaunchCommand(); proc.Start(); } static public void StopService() { System.Diagnostics.Process proc = new System.Diagnostics.Process(); proc.EnableRaisingEvents = false; proc.StartInfo.FileName = "javaw"; proc.StartInfo.Arguments = "-jar stop.jar"; proc.Start(); } Firstly I had to use Threads in OnStart and OnStop. If not, an exception occurs complaining that the service is terminated because of doing nothing. Secondly, the service can be hooked up to windows smoothly. However, the service terminates a short while after it is started. I looked into the process monitor, only the service process stays alive for that short while, the javaw process never showed up, however. Is there anyone who knows how this can be fixed? It works fine in an ordinary console environment. I think it has something to do with Windows service.

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• Javascript libraries + JQuery plugins contradict? How to debug?

  - by Metafaniel

  This is somewhat a newbie question... I effort everyday to learn, so please understand ;) I'm not the very best expert, but I can do a decent job good looking and functional websites or web applications. My main tools are PHP5, HTML5, CSS2 y 3, a database (SQLite, MySQL) and Javascript and JQuery. I'm not an expert at all in Javascript. I often find interesting JQuery plugins or tutorials and try to mix them up to do the functionality needed. This time I'm mixing maybe too much plugins and js files from different sources. In fact, my app do what I want except for certain behaviors... There are no errors, everything looks fine, but the misbehavior persists. So maybe I need to specify a class I don't know about, or one contradicts another one from another plugin and I just can't understand, for example, why a <button type="button">DON'T submit</button> just submits the form... Anyway, my point is: Do you people know a way to debug this situations??? Is there a generic tool, suggestion, workflow or something to help me understand conflicts or omissions between libraries or plugins??? (Javascript libraries, my own Javascripts and JQuery plugins)??? I hope it is a way! THANKS A LOT FOR YOUR HELP AND COMPREHENSION! =)

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• What's the best way of accessing a DRb object (e.g. Ruby Queue) from Scala (and Java)?

  - by Tom Morris

  I have built a variety of little scripts using Ruby's very simple Queue class, and share the Queue between Ruby and JRuby processes using DRb. It would be nice to be able to access these from Scala (and maybe Java) using JRuby. I've put together something Scala and the JSR-223 interface to access jruby-complete.jar. import javax.script._ class DRbQueue(host: String, port: Int) { private var engine = DRbQueue.factory.getEngineByName("jruby") private var invoker = engine.asInstanceOf[Invocable] engine.eval("require \"drb\" ") private var queue = engine.eval("DRbObject.new(nil, \"druby://" + host + ":" + port.toString + "\")") def isEmpty(): Boolean = invoker.invokeMethod(this.queue, "empty?").asInstanceOf[Boolean] def size(): Long = invoker.invokeMethod(this.queue, "length").asInstanceOf[Long] def threadsWaiting: Long = invoker.invokeMethod(this.queue, "num_waiting").asInstanceOf[Long] def offer(obj: Any) = invoker.invokeMethod(this.queue, "push", obj.asInstanceOf[java.lang.Object]) def poll(): Any = invoker.invokeMethod(this.queue, "pop") def clear(): Unit = { invoker.invokeMethod(this.queue, "clear") } } object DRbQueue { var factory = new ScriptEngineManager() } (It conforms roughly to java.util.Queue interface, but I haven't declared the interface because it doesn't implement the element and peek methods because the Ruby class doesn't offer them.) The problem with this is the type conversion. JRuby is fine with Scala's Strings - because they are Java strings. But if I give it a Scala Int or Long, or one of the other Scala types (List, Set, RichString, Array, Symbol) or some other custom type. This seems unnecessarily hacky: surely there has got to be a better way of doing RMI/DRb interop without having to use JSR-223 API. I could either make it so that the offer method serializes the object to, say, a JSON string and takes a structural type of only objects that have a toJson method. I could then write a Ruby wrapper class (or just monkeypatch Queue) to would parse the JSON. Is there any point in carrying on with trying to access DRb from Java/Scala? Might it just be easier to install a real message queue? (If so, any suggestions for a lightweight JVM-based MQ?)

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• Support clicking a link, but sending a POST (vs GET) to the server, without Ajax?

  - by xyld

  I'm thinking this isn't exactly possible, but maybe I'm wrong. I'm simply torn between those who believe that only POST requests should modify data on the server and people that relax the rule and allow GET requests to modify data. Take this situation. Say you have a table, each row is a row in the database. I'd like to allow them to delete the row via a fancy "X" icon as the very last <td></td> element in the row. AFAIK, the only way to send a POST to the server is via a form. But do I really stuff an entire form into the last <td></td> element just to do a POST? Or should I cheat and use an <a href=...></a> tag that sends a GET request? You may be thinking "Do both! Send a POST AND use the <a ...></a> tag! Use fancy javascript + xhr!" And I'll say, oh? And how will that degrade in a zero javascript environment? Maybe we've reached a point when it doesn't make sense to worry about gracefully degrading? I'm not sure. You tell me? I'm new to web development, but I understand most of the concepts involved.

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• Splitting a set of object into several subsets of 'similar' objects

  - by doublep

  Suppose I have a set of objects, S. There is an algorithm f that, given a set S builds certain data structure D on it: f(S) = D. If S is large and/or contains vastly different objects, D becomes large, to the point of being unusable (i.e. not fitting in allotted memory). To overcome this, I split S into several non-intersecting subsets: S = S1 + S2 + ... + Sn and build Di for each subset. Using n structures is less efficient than using one, but at least this way I can fit into memory constraints. Since size of f(S) grows faster than S itself, combined size of Di is much less than size of D. However, it is still desirable to reduce n, i.e. the number of subsets; or reduce the combined size of Di. For this, I need to split S in such a way that each Si contains "similar" objects, because then f will produce a smaller output structure if input objects are "similar enough" to each other. The problems is that while "similarity" of objects in S and size of f(S) do correlate, there is no way to compute the latter other than just evaluating f(S), and f is not quite fast. Algorithm I have currently is to iteratively add each next object from S into one of Si, so that this results in the least possible (at this stage) increase in combined Di size: for x in S: i = such i that size(f(Si + {x})) - size(f(Si)) is min Si = Si + {x} This gives practically useful results, but certainly pretty far from optimum (i.e. the minimal possible combined size). Also, this is slow. To speed up somewhat, I compute size(f(Si + {x})) - size(f(Si)) only for those i where x is "similar enough" to objects already in Si. Is there any standard approach to such kinds of problems? I know of branch and bounds algorithm family, but it cannot be applied here because it would be prohibitively slow. My guess is that it is simply not possible to compute optimal distribution of S into Si in reasonable time. But is there some common iteratively improving algorithm?

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• Invert the 1bbp color under a rectangle.

  - by Scott Chamberlain

  I am working with GDI+, the image I am working with is a 1bbp image. What i would like to do is draw a rectangle on the image and everything under that rectangle will be inverted (white pixels will become black and black pixels become white). All of the sample code I have seen is for 8 bit RGB color scale images, and I don't think the techniques they use will work for me. Here is the code I have so far. This is the parent control, one of the Epl2.IDrawableCommand's will be the command that does the inverting. protected override void OnPaint(PaintEventArgs e) { base.OnPaint(e); if (Label != null) { using (Bitmap drawnLabel = new Bitmap((int)((float)Label.LabelHeight * _ImageScaleFactor), (int)((float)Label.LableLength *(int) _ImageScaleFactor), System.Drawing.Imaging.PixelFormat.Format1bppIndexed)) { using (Graphics drawBuffer = Graphics.FromImage(drawnLabel)) { drawBuffer.ScaleTransform(_ImageScaleFactor, _ImageScaleFactor); foreach (Epl2.IDrawableCommand cmd in Label.Collection) { cmd.Paint(drawBuffer); } drawBuffer.ResetTransform(); } drawnLabel.RotateFlip(Rotation); pbLabelDrawArea.Size = drawnLabel.Size; using (Graphics drawArea = pbLabelDrawArea.CreateGraphics()) { drawArea.Clear(Color.White); drawArea.DrawImage(drawnLabel, new Point(0, 0)); } } } } What should I put in the Paint(Graphic g) for this command?

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• LINQ query to find if items in a list are contained in another list

  - by cjohns

  I have the following code: List<string> test1 = new List<string> { "@bob.com", "@tom.com" }; List<string> test2 = new List<string> { "[email protected]", "[email protected]" }; I need to remove anyone in test2 that has @bob.com or @tom.com. What I have tried is this: bool bContained1 = test1.Contains(test2); bool bContained2 = test2.Contains(test1); bContained1 = false but bContained2 = true. I would prefer not to loop through each list but instead use a Linq query to retrieve the data. bContained1 is the same condition for the Linq query that I have created below: List<string> test3 = test1.Where(w => !test2.Contains(w)).ToList(); The query above works on an exact match but not partial matches. I have looked at other queries but I can find a close comparison to this with Linq. Any ideas or anywhere you can point me to would be a great help.

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• How to iterate JPA collections in Google App engine

  - by palto

  Hi I use Google App Engine with datanucleus and JPA. I'm having a real hard time grasping how I'm supposed to read stuff from data store and pass it to JSP. If I load a list of POJOs with entitymanager and pass it to JSP, it crashes to org.datanucleus.exceptions.NucleusUserException: Object Manager has been closed. I understand why this is happening. Obviously because I fetch the list, close the entity manager and pass it to JSP, at which point it will fail because the list is lazy. How do I make the list NOT lazy without resorting to hacks like calling size() or something like that? Here is what I'm trying to do: @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setAttribute("parties", getParties()); RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/WEB-INF/parties.jsp"); dispatcher.forward(req, resp); } private List<Party> getParties(){ EntityManager em = entityManagerProvider.get(); try{ Query query = em.createQuery("SELECT p FROM Party p"); return query.getResultList(); }finally{ em.close(); } }

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