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  • What's the correct terminology for something that isn't quite classification nor regression?

    - by TC
    Let's say that I have a problem that is basicly classification. That is, given some input and a number of possible output classes, find the correct class for the given input. Neural networks and decision trees are some of the algorithms that may be used to solve such problems. These algorithms typically only emit a single result however: the resulting classification. Now what if I weren't only interested in one classification, but in the posterior probabilities that the input belongs to each of the classes. I.E., instead of the answer "This input belongs in class A", I want the answer "This input belongs to class A with 80%, class B with 15% and class C with 5%". My question is not on how to obtain these posterior probabilities, but rather on the correct terminology to describe the process of finding them. You could call it regression, since we are now trying to estimate a number of real valued numbers, but I am not quite sure if that's right. I feel it's not exactly classification either, it's something in between the two. Is there a word that describes the process of finding the class conditional posterior probabilities that some input belongs in each of the possible output classes? P.S. I'm not exactly sure if this question is enough of a programming question, but since it's about machine learning and machine learning generally involves a decent amount of programming, let's give it a shot.

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  • Writing an auto-memoizer in Scheme. Help with macro and a wrapper.

    - by kunjaan
    I am facing a couple of problems while writing an auto-memoizer in Scheme. I have a working memoizer function, which creats a hash table and checks if the value is already computed. If it has been computed before then it returns the value else it calls the function. (define (memoizer fun) (let ((a-table (make-hash))) (?(n) (define false-if-fail (?() #f)) (let ((return-val (hash-ref a-table n false-if-fail))) (if return-val return-val (begin (hash-set! a-table n (fun n)) (hash-ref a-table n))))))) Now I want to create a memoize-wrapper function like this: (define (memoize-wrapper function) (set! function (memoizer function))) And hopefully create a macro called def-memo which defines the function with the memoize-wrapper. eg. the macro could expand to (memoizer (define function-name arguments body ...) or something like that. So that I should be able to do : (def-memo (factorial n) (cond ((= n 1) 1) (else (* n (factorial (- n 1)))))) which should create a memoized version of the factorial instead of the normal slow one. My problem is that the The memoize-wrapper is not working properly, it doesnt call the memoized function but the original function. I have no idea how to write a define inside of the macro. How do I make sure that I can get variable lenght arguments and variable length body? How do I then define the function and wrap it around with the memoizer? Thanks a lot.

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  • Creating a new object destroys an older object with different name in C++

    - by Mikael
    First question here! So, I am having some problems with pointers in Visual C++ 2008. I'm writing a program which will control six cameras and do some processing on them so to clean things up I have created a Camera Manager class. This class handles all operations which will be carried out on all the cameras. Below this is a Camera class which interacts with each individual camera driver and does some basic image processing. Now, the idea is that when the manager is initialised it creates two cameras and adds them to a vector so that I can access them later. The catch here is that when I create the second camera (camera2) the first camera's destructor is called for some reason, which then disconnects the camera. Normally I'd assume that the problem is somewhere in the Camera class, but in this case everything works perfectly as long as I don't create the camera2 object. What's gone wrong? CameraManager.h: #include "stdafx.h" #include <vector> #include "Camera.h" class CameraManager{ std::vector<Camera> cameras; public: CameraManager(); ~CameraManager(); void CaptureAll(); void ShowAll(); }; CameraManager.cpp: #include "stdafx.h" #include "CameraManager.h" CameraManager::CameraManager() { printf("Camera Manager: Initializing\n"); [...] Camera *camera1 = new Camera(NodeInfo,1, -44,0,0); cameras.push_back(*camera1); // Adding the following two lines causes camera1's destructor to be called. Why? Camera *camera2 = new Camera(NodeInfo,0, 44,0,0); cameras.push_back(*camera2); printf("Camera Manager: Ready\n"); }

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  • Git rebase and semi-tracked per-developer config files.

    - by dougkiwi
    This is my first SO question and I'm new-ish to Git as well. Background: I am supposed to be the version control guru for Git in my group of about 8 developers. As I don't have a lot of Git experience, this is exciting. I decided we need a shared repository that would be the authoritative master for the production code and the main meeting-point for the development code. As we work for a corporation, we really do need to show an authoritive source for the production code at least. I have instructed the developers to pull-rebase when pulling from the shared repository, then push the commits that they want to share. We have been running into problems with a particular type of file. One of these files, which I currently assume is typical of the problem, is called web.config. We want a version-controlled master web.config for devs to clone, but each dev may make minor edits to this file that they wish to locally save but not share. The problem is this: how do I tell git not to consider local changes or commits to this file to be relevent for rebasing and pushing? Gitignore does not seem to solve the problem, but maybe that's because I put web.config into .gitignore too late? In some simple situations we have stacked local changes, rebased, pushed, and popped the stack, but that doesn't seem to work all of the time. I haven't picked up the pattern quite yet. The published documentation on pull --rebase tends to deal with simplier situations. Or do I have the wrong idea entirely? Are we misusing Git? Dougkiwi

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  • Why I can't get all UDP packets?

    - by Jack
    My program use UdpClient to try to receive 27 responses from 27 hosts. The size of the response is 10KB. My broadband incoming bandwidth is 150KB/s. The 27 responses are sent from the hosts almost at the same time and for every 10 secs. However, I can only receive 8 - 17 responses each time. The number of responses that I can receive is quite dynamic but within the range. Can anyone tell me why? why can't I receive all? I understand UDP is not reliable. but I tried receiving 5 - 10 responses at the same time, it worked. I guess the network links are not so bad. The code is very simple. ON the 27 hosts, I just use UdpClient to send 10KB to my machine. On my machine, I have one UdpClient receive datagrams. Each time I get a data, I create a thread to handle it (basically handling it means just print out "I received 10KB", but it runs in a thread). listener = new UDPListener(Port); listener.Start(); while (true) { try { UDPContext context = listener.Accept(); ThreadPool.QueueUserWorkItem(new WaitCallback(HandleMessage), context); } catch (Exception) { } } If I reduce the size of the response down to 3KB, the case gets much better that roughly 25 responses can be received. Any more idea? UDP buffer problems???

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  • SQL Group by Minute- Expanded

    - by Barnie
    I am working on something similar to this post here: TS SQL - group by minute However mine is pulling from an message queue, and I need to see an accurate count of the amount of traffic the Message Queue is creating/ sending, and at what time Select * From MessageQueue mq My expanded version of this though is the following: A) User defines a start time and an end time (Easy enough using Declare's @StartTime and @EndTime B) Give the user the option of choosing the "grouping". Will it be broken out by 1 minutes, 5 minutes, 15 minutes, or 30 minutes (Max). (I had thought to do this with a CASE statement, but my test problems fall apart on me.) C) Display the data to accurately show a count of what happened during the interval (Grouping) selected. This is where I am at so far SQL Blob: DECLARE @StartTime datetime DECLARE @EndTime datetime SELECT DATEPART(n, mq.cre_date)/5 as Time --Trying to just sort by 5 minute intervals ,CONVERT(VARCHAR(10),mq.Cre_Date,101) ,COUNT(*) as results FROM dbo.MessageQueue mq WHERE mq.cre_date BETWEEN @StartDate AND @EndDate GROUP BY DATEPART(n, mq.cre_date)/5 --Trying to just sort by 5 minute intervals , eq.Cre_Date This is the output I would like to achieve: [Time] [Date] [Message Count] 1300 06/26/2012 5 1305 06/26/2012 1 1310 06/26/2012 100

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  • Returning C++ objects from Windows DLL

    - by R Samuel Klatchko
    Due to how Microsoft implements the heap in their non-DLL versions of the runtime, returning a C++ object from a DLL can cause problems: // dll.h DLL_EXPORT std::string somefunc(); and: // app.c - not part of DLL but in the main executable void doit() { std::string str(somefunc()); } The above code runs fine provided both the DLL and the EXE are built with the Multi-threaded DLL runtime library. But if the DLL and EXE are built without the DLL runtime library (either the single or multi-threaded versions), the code above fails (with a debug runtime, the code aborts immediately due to the assertion _CrtIsValidHeapPointer(pUserData) failing; with a non-debug runtime the heap gets corrupted and the program eventually fails elsewhere). Two questions: Is there a way to solve this other then requiring that all code use the DLL runtime? For people who distribute their libraries to third parties, how do you handle this? Do you not use C++ objects in your API? Do you require users of your library to use the DLL runtime? Something else?

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  • How to use db4o IObjectContainer in a web application ? (Container lifetime ?)

    - by driis
    I am evaluating db4o for persistence for a ASP .NET MVC project. I am wondering how I should use the IObjectContainer in a web context with regards to object lifetime. As I see it, I can do one of the following: Create the IObjectContainer at application startup and keep the same instance for the entire application lifetime. Create one IObjectContainer per request. Start a server, and get a client IObjectContainer for each database interaction. What are the implications of these options, in terms of performance and concurrency ? Since the database is locked when an IObjectContainer is opened, I am pretty sure that option 2) would get me some problems with concurrency - would this also be the case for option 1 ? As I understand it, if I retrieve an object from an IObjectContainer, it must be saved by the same IObjectContainer instance - in order for db4o to identify it as being the same object. Therefore, If I choose option 3), I would have to retrieve the original object, make the necessary changes (copy data from a modified object), and then store it using the same IObjectContainer. Is this true ?

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  • How to optimize shopping carts for minimal prices?

    - by tangens
    I have a list of items I want to buy. The items are offered by different shops and different prices. The shops have individual delivery costs. I'm looking for an optimal shopping strategy (and a java library supporting it) to purchase all of the items with a minimal total price. Example: Item1 is offered at Shop1 for $100, at Shop2 for $111. Item2 is offered at Shop1 for $90, at Shop2 for $85. Delivery cost of Shop1: $10 if total order < $150; $0 otherwise Delivery cost of Shop2: $5 if total order < $50; $0 otherwise If I buy Item1 and Item2 at Shop1 the total cost is $100 + $90 +$0 = $190. If I buy Item1 and Item2 at Shop2 the total cost is $111 + $85 +$0 = $196. If I buy Item1 at Shop1 and Item2 at Shop2 the total cost is $100 + $10 + $85 + $0 = 195. I get the minimal price if I order Item1 at Shop1 and Item2 at Shop2: $195 Question I need some hints which algorithms may help me to solve optimization problems of this kind for number of items about 100 and number of shops about 20. I already looked at apache-math and its optimization package, but I have no idea what algorithm to look for.

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  • Wicket application + Apache + mod_jk - AJP queues are filling up!

    - by nojyarg
    Dear community, We are having a Wicket-based Java application deployed in a production server cluster using Apache (2.2.3) with mod_jk (1.2.30) as load balancing component w/ sticky session and Jboss 5 as application container for the Java application. We are inconsistently seeing an issue in our production environment where our AJP queues between Apache and Jboss as shown in the JMX console fill up with requests to the point where the application server is no longer taking on any new requests. When looking at all involved system components (overall traffic, load db, process list db, load of all clustered application server nodes) nothing points towards a capacity issue which would explain why the calls are being stalled in the AJP queue. Instead all systems appear sufficiently idle. So far, our only remedy to this issue is to restart the appservers and the load balancer which only occasionally clears the AJP queues. We are trying to figure out why the queues are filling up to the point that no calls get returned to the end user although the system is not under a high load. Has anyone else experienced similar problems? Are there any other system metrics we should monitor that could explain the queuing behavior? Is this potentially a mod_jk issue? If so, is it advisable to swap mod_jk with mod_cluster to resolve the issue? Any advice is highly appreciated. If I can provide additional information for the sake of troubleshooting I would be more than willing to do so. /Ben

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  • Python parsing error message functions

    - by user1716168
    The code below was created by me with the help of many SO veterans: The code takes an entered math expression and splits it into operators and operands for later use. I have created two functions, the parsing function that splits, and the error function. I am having problems with the error function because it won't display my error messages and I feel the function is being ignored when the code runs. An error should print if an expression such as this is entered: 3//3+4,etc. where there are two operators together, or there are more than two operators in the expression overall, but the error messages dont print. My code is below: def errors(): numExtrapolation,opExtrapolation=parse(expression) if (len(numExtrapolation) == 3) and (len(opExtrapolation) !=2): print("Bad1") if (len(numExtrapolation) ==2) and (len(opExtrapolation) !=1): print("Bad2") def parse(expression): operators= set("*/+-") opExtrapolate= [] numExtrapolate= [] buff=[] for i in expression: if i in operators: numExtrapolate.append(''.join(buff)) buff= [] opExtrapolate.append(i) opExtrapolation=opExtrapolate else: buff.append(i) numExtrapolate.append(''.join(buff)) numExtrapolation=numExtrapolate #just some debugging print statements print(numExtrapolation) print("z:", len(opExtrapolation)) return numExtrapolation, opExtrapolation errors() Any help would be appreciated. Please don't introduce new code that is any more advanced than the code already here. I am looking for a solution to my problem... not large new code segments. Thanks.

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  • Whats wrong with this video embed code?

    - by jamietelin
    Following embed code is from http://hd.se/landskrona/2010/04/09/kunglig-glans-pa-idrottsgalan/ but it doesn't work in Internet Explorer 8. Firefox no problems. Any recommendations for improvements? Thanks for your time! <object width="480px" height="294px" id="_36313041" data="http://hd.se/static/media/html/flash/video-3/flowplayer.swf" type="application/x-shockwave-flash"> <param name="movie" value="http://hd.se/static/media/html/flash/video-3/flowplayer.swf" /> <param name="allowfullscreen" value="true" /> <param name="allowscriptaccess" value="always" /> <param name="flashvars" value='config={"key":"$3fff7448b28a8cffc85","contextMenu":["hd.se videospelare 1.0"],"plugins":{"rtmp":{"url":"http://hd.se/static/media/html/flash/video-3/flowplayer.rtmp.swf"},"controls":{"height":24,"opacity":1,"all":false,"play":true,"time":true,"scrubber":true,"playlist":false,"mute":true,"volume":true,"fullscreen":true,"backgroundColor":"#222222","backgroundGradient":"none","buttonColor":"#7c7c7c","buttonOverColor":"#36558b","progressColor":"#7c7c7c","bufferColor":"#7c7c7c","timeColor":"#ffffff","durationColor":"#ffffff","timeBgColor":"#222222","scrubberHeightRatio":0.5,"scrubberBarHeightRatio":0.5,"volumeSliderHeightRatio":0.5,"volumeBarHeightRatio":0.5,"autoHide":"fullscreen","hideDelay":1800,"tooltips":{"buttons":true,"play":"Spela","pause":"Paus","next":"Nästa","previous":"Föregående","mute":"Ljud av","unmute":"Ljud på","fullscreen":"Fullskärmsläge","fullscreenExit":"Lämna fullskärmsläge"},"tooltipColor":"#153872","tooltipTextColor":"#ffffff"},"contentIntro":{"url":"http://hd.se/static/media/html/flash/video-3/flowplayer.content.swf","top":0,"width":736,"border":"none","backgroundColor":"#202020","backgroundGradient":"none","borderRadius":"none","opacity":"85pct","display":"none","closeButton":true}},"canvas":{"backgroundColor":"#000000","backgroundGradient":"none"},"play":{"replayLabel":"Spela igen"},"screen":{"bottom":24},"clip":{"scaling":"fit","autoPlay":true},"playlist":[{"provider":"rtmp","netConnectionUrl":"rtmp://fl0.c06062.cdn.qbrick.com/06062","url":"ncode/hdstart","autoPlay":false,"scaling":"fit"},{"url":"http://hd.se/multimedia/archive/00425/_kunligglans_HD_VP6_425359a.flv","scaling":"fit","autoPlay":true},{"provider":"rtmp","netConnectionUrl":"rtmp://fl0.c06062.cdn.qbrick.com/06062","url":"ncode/hdstopp","autoPlay":true,"scaling":"fit"}]}' /> </object>

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  • CXF code first service, WSDL generation; soap:address changes?

    - by jcalvert
    I have a simple Java interface/implementation I am exposing via CXF. I have a jaxws element in my Spring configuration file like this: <jaxws:endpoint id="managementServiceJaxws" implementor="#managementService" address="/jaxws/ManagementService" > </jaxws:endpoint> It generates the WSDL from my annotated interface and exposes the service. Then when I hit http://myhostname/cxf/jaxws/ManagementService?wsdl I get a lovely WSDL. At the bottom in the wsdl:service element, I'll see <soap:address location="http://myhostname/cxf/jaxws/ManagementService"/> However, some time a day or so later, with no application restart, hitting that same url produces: This causes a number of problems, but what I really want is to fix it. Right now, there's a particular client to the webservice that sets the endpoint to localhost; because it runs on the same machine. Is it possible the wsdl is getting regenerated and cached and then exposing the 'localhost' version? In part I don't know the exact mechanism by which one goes from a ?wsdl request in CXF to the response. It seems almost certain that it's retrieving some cached version, given that it's supposed to be determining the address by asking the servletcontainer (Jetty). For reference I know a stopgap solution is using the hostname on the client and making sure an alias in place so that it goes over the loopback. EDIT: For reference, I confirmed that if I bring my application up and first hit it over localhost, then querying for the wsdl via the hostname shows the address as localhost. Conversely, first hitting it over the hostname causes localhost requests to show the hostname. So obviously something is getting cached here.

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  • In C/C++ mode in Emacs, change face of code in #if 0...#endif block to comment face

    - by pogopop77
    I'm trying to add functionality found in some other code editors to my Emacs configuration, whereby C/C++ code within #if 0...#endif blocks is automatically set to the comment face/font. Based on my testing, cpp-highlight-mode does something like what I want, but requires user action. It seems like tying into the font-lock functionality is the correct option to make the behavior automatic. I have successfully followed examples in the GNU documentation to change the face of single-line regular expressions. For example: (add-hook 'c-mode-common-hook (lambda () (font-lock-add-keywords nil '(("\\<\\(FIXME\\|TODO\\|HACK\\|fixme\\|todo\\|hack\\)" 1 font-lock-warning-face t))))) works fine to highlight debug related keywords anywhere in a file. However, I am having problems matching #if 0...#endif as a multiline regular expression. I found some useful information in this post (How to compose region like ""), that suggested that Emacs must be told specifically to allow for multiline matches. But this code: (add-hook 'c-mode-common-hook (lambda () '(progn (setq font-lock-multiline t) (font-lock-add-keywords nil '(("#if 0\\(.\\|\n\\)*?#endif" 1 font-lock-comment-face t)))))) still does not work for me. Perhaps my regular expression is wrong (though it appears to work using M-x re-builder), I've messed up my syntax, or I'm following the wrong approach entirely. I'm using Aquamacs 2.1 (which is based on GNU Emacs 23.2.50.1) on OS X 10.6.5, if that makes a difference. Any assistance would be appreciated!

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  • OCaml delimiters and scopes

    - by Jack
    Hello! I'm learning OCaml and although I have years of experience with imperative programming languages (C, C++, Java) I'm getting some problems with delimiters between declarations or expressions in OCaml syntax. Basically I understood that I have to use ; to concatenate expressions and the value returned by the sequence will be the one of last expression used, so for example if I have exp1; exp2; exp3 it will be considered as an expression that returns the value of exp3. Starting from this I could use let t = something in exp1; exp2; exp3 and it should be ok, right? When am I supposed to use the double semicol ;;? What does it exactly mean? Are there other delimiters that I must use to avoid syntax errors? I'll give you an example: let rec satisfy dtmc state pformula = match (state, pformula) with (state, `Next sformula) -> let s = satisfy_each dtmc sformula and adder a state = let p = 0.; for i = 0 to dtmc.matrix.rows do p <- p +. get dtmc.matrix i state.index done; a +. p in List.fold_left adder 0. s | _ -> [] It gives me syntax error on | but I don't get why.. what am I missing? This is a problem that occurs often and I have to try many different solutions until it suddently works :/ A side question: declaring with let instead that let .. in will define a var binding that lasts whenever after it has been defined? What I basically ask is: what are the delimiters I have to use and when I have to use them. In addition are there differences I should consider while using the interpreter ocaml instead that the compiler ocamlc? Thanks in advance!

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  • Apply [ThreadStatic] attribute to a method in external assembly

    - by Sen Jacob
    Can I use an external assembly's static method like [ThreadStatic] method? Here is my situation. The assembly class (which I do not have access to its source) has this structure public class RegistrationManager() { private RegistrationManager() {} public static void RegisterConfiguration(int ID) {} public static object DoWork() {} public static void UnregisterConfiguration(int ID) {} } Once registered, I cannot call the DoWork() with a different ID without unregistering the previously registered one. Actually I want to call the DoWork() method with different IDs simultaneously with multi-threading. If the RegisterConfiguration(int ID) method was [ThreadStatic], I could have call it in different threads without problems with calls, right? So, can I apply the [ThreadStatic] attribute to this method or is there any other way I can call the two static methods same time without waiting for other thread to unregister it? If I check it like the following, it should work. for(int i=0; i < 10; i++) { new Thread(new ThreadStart(() => Checker(i))).Start(); } public string Checker(int i) { public static void RegisterConfiguration(i); // Now i cannot register second time public static object DoWork(i); Thread.Sleep(5000); // DoWork() may take a little while to complete before unregistered public static void UnregisterConfiguration(i); }

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  • Multiple Exception Handling in one if statement [closed]

    - by JA3N
    I am having trouble with throwing and catching exceptions. Here is the code for assignSeat(), assignSeat is called in a try block in another class. void assignSeat(String passengerName, int x, int y) throws SeatOccupiedException, InvalidPassengerNameException { Seat tSeat = airplane.getSeat(x,y); if (tSeat!=null) { if (passengerName.isEmpty() || !passengerName.matches("[a-zA-Z]+")) { throw new InvalidPassengerNameException(); } //excluded else if else if (foundPassenger(passengerName)) { airplane.seatList.get(airplane.seatNumber(passengerName)).unOccupy(); tSeat.occupy(); for (int i = 0; i<passengers.size();i++) if (passengers.get(i).getName().equals(passengerName)) passengers.get(i).changeSeat(tSeat.getSeatName()); } else if (!tSeat.occupied) { tSeat.occupy(); addPassenger(passengerName, tSeat.getSeatName()); } else if (tSeat.occupied) { throw new SeatOccupiedException(); } } and here is the code that calls assignSeat() and is in another class (I won't copy the whole class to make it look clearer) if (afComp.currentAF != null) { try { afComp.currentAF.assignSeat(nameField.getText(), x, y); //<-Problem here, "Unhandled exception type SeatOccupiedException" } catch (SeatOccupiedException exception) //<-Problem here, "Unreachable catch block, This exception is never thrown from the try statement body" { } catch(InvalidPassengerNameException exception) //<-No problems. { } } Whats wrong with the try block? why won't it throw the SeatOccupiedException? Exception classes: SeatOccupied: package a2; public class SeatOccupiedException extends Exception { public SeatOccupiedException(){} } InvalidPassengerName: package a2; public class InvalidPassengerNameException extends Exception { public InvalidPassengerNameException() {} } Every class I have is in package a2 imports for class that calls assignSeat package a2; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; import java.awt.event.MouseEvent; import java.awt.BorderLayout; import javax.swing.*; import javax.swing.event.*; imports for class that has assignSeat package a2; import java.util.ArrayList;

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  • Object Design catalog and resources

    - by Tauren
    I'm looking for web sites, books, or other resources that provide a catalog of object designs used in common scenarios. I'm not looking for generic design patterns, but for samples of actual object designs that were used to solve real problems. For instance, I'm about to build an internal messaging system for a web application, similar to Facebook's messaging system. This system will allow administrators to send messages to all members, to selected groups of members, or to individuals. Members can send messages to other members or groups of members. Fairly common stuff and a feature that I'm sure thousands of web applications require. I know each situation is different and there are a million ways to design this solution. Although this scenario isn't really all that complex, I'm sure the basic design of the necessary objects and relationships for a system like this has already been done many times. It would be nice to review other similar designs before building my own. Is there a place where people can share their designs and others can browse/search through the catalog to review and provide feedback on them? StackOverflow could be used to a degree for this, but doesn't really provide a catalog of designs. Any other resources that would relate?

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  • What changed in the DataGrid that means it won't work anymore?

    - by Jeff Yates
    I have a Silverlight app with a DataGrid containing some custom columns and all was working well. Then I updated to Silverlight 3 tools for VS 2008 SP1 and rebuilt it. Now it has the following problems: Rows aren't added when the collection is modified. The ItemsSource property is (and always has been) set to an ObservableCollection instance, which notifies when its contents change. This worked fine for Silverlight 2. However, in Silverlight 3 to get this working at all, I now have to null and then re-set ItemsSource - this seems like I'm hiding a bigger issue but I can't work out what that might be. I cannot select a row or a cell anymore. If I'm lucky, I can select one whole row before it stops working. I can't edit anything. I suspect this is related to the previous point. I'll post some source when I am able, but first I have to strip it down to the bare minimum. In the meantime, I was hoping someone might have some idea of what may be going on here. My gut feeling on the second two points is that my bindings are no longer working, but that's just a guess and if it is the case, I have no idea which ones. Thanks for any help anyone might be able to provide. Update So, I finally reduced my problem down to a simple works/doesn't work comparison. The problem seems to occur if I override Equals in my element type. As soon as I do that, something happens strangely in the ObservableCollection that contains that type, it seems, and my application breaks. To make it more interesting, there is a check to make sure that duplicate items don't even get close to being added to the collection. I don't exactly know why ObservableCollection needs to compare equality when inserting items (the stack trace indicates it is using IndexAt) but this seems to cause the issue. So, any thoughts?

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  • How to handle build rule with unknown targets in OMake when target list generator is built

    - by Michael E
    I have a project which uses OMake for its build system, and I am trying to handle a rather tough corner case. I have some definition files and a tool which can take these definition files and create GraphViz files. There are two problems, though: Each definition file can produce multiple graphs, and the list of graphs it can produce is encoded in the file. My dump tool does have a -list option which lists all the graphs a definition file will produce. This dump tool is built in the source tree. I want this list available in the OMakefile so I can use other rules to convert the DOT files to SVG, and have a phony target depend on all the SVGs (goal: a single build command which builds SVG descriptions of all my graphs). If I only had the first problem, it would be easy - I would run the tool to build a list, and then use that list to build a target which invokes the dumper to output the GraphViz files. However, I am rather stuck on forcing the dump tool to be built before it is needed. If this were make, I would just run make recursively to build the dump tool. OMake does not allow recursive invocation, however, and the build function is only usable from osh. Any suggestions for a good solution to this problem?

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  • C++ design related question

    - by Kotti
    Hi! Here is the question's plot: suppose I have some abstract classes for objects, let's call it Object. It's definition would include 2D position and dimensions. Let it also have some virtual void Render(Backend& backend) const = 0 method used for rendering. Now I specialize my inheritance tree and add Rectangle and Ellipse class. Guess they won't have their own properties, but they will have their own virtual void Render method. Let's say I implemented these methods, so that Render for Rectangle actually draws some rectangle, and the same for ellipse. Now, I add some object called Plane, which is defined as class Plane : public Rectangle and has a private member of std::vector<Object*> plane_objects; Right after that I add a method to add some object to my plane. And here comes the question. If I design this method as void AddObject(Object& object) I would face trouble like I won't be able to call virtual functions, because I would have to do something like plane_objects.push_back(new Object(object)); and this should be push_back(new Rectangle(object)) for rectangles and new Circle(...) for circles. If I implement this method as void AddObject(Object* object), it looks good, but then somewhere else this means making call like plane.AddObject(new Rectangle(params)); and this is generally a mess because then it's not clear which part of my program should free the allocated memory. ["when destroying the plane? why? are we sure that calls to AddObject were only done as AddObject(new something).] I guess the problems caused by using the second approach could be solved using smart pointers, but I am sure there have to be something better. Any ideas?

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  • Create table and call it from sql

    - by user1770816
    I have a PL/SQL function which creates a new temporary table. For creating the table I use execute immediate. When I run my function in oracle sql developer everything is ok; the function creates the temp table without errors. But when U use SQL: Select function_name from table_name I get an exceptions: ORA-14552: cannot perform a DDL, commit or rollback inside a query or DML ORA-06512: at "SYSTEM.GET_USERS", line 10 14552. 00000 - "cannot perform a DDL, commit or rollback inside a query or DML " *Cause: DDL operations like creation tables, views etc. and transaction control statements such as commit/rollback cannot be performed inside a query or a DML statement. Update Sorry, write from tablet PC and have problems with format text. My function: CREATE OR REPLACE FUNCTION GET_USERS ( USERID IN VARCHAR2 ) RETURN VARCHAR2 AS request VARCHAR2(520) := 'CREATE GLOBAL TEMPORARY TABLE '; BEGIN request := request || 'temp_table_' || userid || '(user_name varchar2(50), user_id varchar2(20), is_administrator varchar2(5)') || ' ON COMMIT PRESERVE ROWS'; EXECUTE IMMEDIATE (request); RETURN 'true'; END GET_USERS;

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  • Business Tier | client state in desktop application- way around Stateful Session Beans?

    - by arthur
    I read positive inputs on the following posts concerning client state management: Stateful EJBs in web application?, here, and here. I want to know how implement such client state management for desktop applications (Swing, AWT, SWT, and other). let's assume there are n desktop clients supposed to use some (remote) services provided on an Application Server. How to maintain a separate and permanent data state for each client , distinct from the other without have to use using stateful session Beans (SFSB) ? is that even possible on this application type ? With Webapp(Servlets / JsSF and JSP) some can avoid using SFSB by HttpSession object and/or coupling it with stateless session beans (SLSB). HttpSession object would keep information for each (Web)client separate and the SLSB would play the business logic music. But HttpSession objects aren't present on desktop application and I go stuck with only SFSB and SLSB. Knowing the problems(Concurrency, Error Handling, usw ) of SFSB, I would have not wanted to use it. What would be the other options? is there only SFSB available? Thanks in advances

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  • [Ruby] Modifying object inside a loop doesn't change object outside of the loop?

    - by Jergason
    I am having problems with modifying objects inside blocks and not getting the expected values outside the blocks. This chunk of code is supposed to transform a bunch of points in 3d space, calculate a score (the rmsd or root mean squared deviation), and store both the score and the set of points that produced that score if it is lower than the current lowest score. At the end, I want to print out the best bunch of points. first = get_transformed_points(ARGV[0]) second = get_transformed_points(ARGV[1]) best_rmsd = first.rmsd(second) best_points = second #transform the points around x, y, and z and get the rmsd. If the new points # have a smaller rmsd, store them. ROTATION = 30 #rotate by ROTATION degrees num_rotations = 360/ROTATION radians = ROTATION * (Math::PI/180) num_rotations.times do |i| second = second * x_rotate num_rotations.times do |j| second = second * y_rotate num_rotations.times do |k| second = second * z_rotate rmsd = first.rmsd(second) if rmsd < best_rmsd then best_points = second best_rmsd = rmsd end end end end File.open("#{ARGV[1]}.out", "w") {|f| f.write(best_points.to_s)} I can print out the points that are getting stored inside the block, and they are getting transformed and stored correctly. However, when I write out the points to a file at the end, they are the same as the initial set of points. Somehow the best_points = second chunk doesn't seem to be doing anything outside of the block. It seems like there are some scoping rules that I don't understand here. I had thought that since I declared and defined best_points above, outside of the blocks, that it would be updated inside the blocks. However, it seems that when the blocks end, it somehow reverts back to the original value. Any ideas how to fix this? Is this a problem with blocks specifically?

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  • c++ floating point precision loss: 3015/0.00025298219406977296

    - by SigTerm
    The problem. Microsoft Visual C++ 2005 compiler, 32bit windows xp sp3, amd 64 x2 cpu. Code: double a = 3015.0; double b = 0.00025298219406977296; //*((unsigned __int64*)(&a)) == 0x40a78e0000000000 //*((unsigned __int64*)(&b)) == 0x3f30945640000000 double f = a/b;//3015/0.00025298219406977296; the result of calculation (i.e. "f") is 11917835.000000000 (*((unsigned __int64*)(&f)) == 0x4166bb4160000000) although it should be 11917834.814763514 (i.e. *((unsigned __int64*)(&f)) == 0x4166bb415a128aef). I.e. fractional part is lost. Unfortunately, I need fractional part to be correct. Questions: 1) Why does this happen? 2) How can I fix the problem? Additional info: 0) The result is taken directly from "watch" window (it wasn't printed, and I didn't forget to set printing precision). I also provided hex dump of floating point variable, so I'm absolutely sure about calculation result. 1) The disassembly of f = a/b is: fld qword ptr [a] fdiv qword ptr [b] fstp qword ptr [f] 2) f = 3015/0.00025298219406977296; yields correct result (f == 11917834.814763514 , *((unsigned __int64*)(&f)) == 0x4166bb415a128aef ), but it looks like in this case result is simply calculated during compile-time: fld qword ptr [__real@4166bb415a128aef (828EA0h)] fstp qword ptr [f] So, how can I fix this problem? P.S. I've found a temporary workaround (i need only fractional part of division, so I simply use f = fmod(a/b)/b at the moment), but I still would like to know how to fix this problem properly - double precision is supposed to be 16 decimal digits, so such calculation isn't supposed to cause problems.

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