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• Using game of life or other virtual environment for artificial (intelligence) life simulation? [clos

  - by Berlin Brown

  One of my interests in AI focuses not so much on data but more on biologic computing. This includes neural networks, mapping the brain, cellular-automata, virtual life and environments. Described below is an exciting project that includes develop a virtual environment for bots to evolve in. "Polyworld is a cross-platform (Linux, Mac OS X) program written by Larry Yaeger to evolve Artificial Intelligence through natural selection and evolutionary algorithms." http://en.wikipedia.org/wiki/Polyworld " Polyworld is a promising project for studying virtual life but it still is far from creating an "intelligent autonomous" agent. Here is my question, in theory, what parameters would you use create an AI environment? Possibly a brain environment? Possibly multiple self contained life organisms that have their own "brain" or life structures. I would like a create a spin on the game of life simulation. What if you have a 64x64 game of life grid. But instead of one grid, you might have N number of grids. The N number of grids are your "life force" If all of the game of life entities die in a particular grid then that entire grid dies. A group of "grids" makes up a life form. I don't have an immediate goal. First, I want to simulate an environment and visualize what is going on in the environment with OpenGL and see if there are any interesting properties to the environment. I then want to add "scarce resources" and see if the AI environment can manage resources adequately.

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• Bespoke Development or Leverage SharePoint With Web Parts etc?

  - by Asim

  Hi all, We are currently in the process of drawing up a solution for an existing client, creating a number of eServices. The client currently have MOSS 2007. The proposed solution is to use MOSS as the launching pad for the eServices… The requirement involves drawing up several online forms which provide registration facilities as well as facilitating a workflow of some sort. I have been told that the proposed solution requires complex web forms. Most are complex forms with parent child details that have multiple windows. The proposed solution is to do some bespoke development, developing ASP .NET forms. These forms would be deployed under the _layouts folder of the current MOSS portal, inheriting the master page design on the current site. I have been told that this approach make development and deployment more simple, as well has having ‘complete integration’ with MOSS. My questions are: Is this the best way to leverage SharePoint – it seems like the proposed solution is not leveraging MOSS at all..! I thought perhaps utilizing Web Parts would be better, but I have been told that this is more complex and developing more smarter intuitive UI is more difficult. Is this really the case? If not, what should be the recommended approach? We will be utilizing Ultimus as the workflow engine. However, I have been recommended K2 Workflows. Anyone used both/have any opinions on either? Many thanks in advance! Kind Regards,

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• Is it possible to prevent out-of-order execution by using single volatile

  - by Yan Cheng CHEOK

  By referring article, it is using a pair of volatile to prevent out-of-order execution. I was wondering, is it possible to prevent it using single volatile? void fun_by_thread_1() { this.isNuclearFactory = true; this.factory = new NuclearFactory(); } void fun_by_thread_2() { Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } // If out-of-order execution happens, _factory might // be NuclearFactory instance. _factory.operate(); } Factory factory = new FoodFactory(); volatile boolean isNuclearFactory = false; The reason I ask, is because I have a single guard flag (similar to isNuclearFactory flag), to guard against multiple variables (similar to many Factory). I do not wish to mark all the Factory as volatile. Or, shall I fall into the following solution? void fun_by_thread_1() { try { writer.lock(); this.isNuclearFactory = true; this.factory = new NuclearFactory(); } finally { writer.unlock(); } } void fun_by_thread_2() { try { reader.lock(); Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } } finally { reader.unlock(); } _factory.operate(); } Factory factory = new FoodFactory(); boolean isNuclearFactory = false; P/S: I know instanceof. Factory is just an example to demonstrate of out-of-order problem.

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• topic-comment naming of functions/methods

  - by Daniel

  I was looking at American Sign Language the other day... and I noticed that the construction of the language was topic-comment. As in "Weather is good". That got me to thinking about why we name methods/functions in the manner of: function getName() { ... } function setName(v) { ... } If we think about naming in a topic-comment function, the function names would be function nameGet() { ... } function nameSet() { ... } This might be better for a class had multiple purposes. IE: class events { function ListAdd(); function ListDelete(); function ListGet(); function EventAdd(); function EventDelete(); function EventGet(); } This way the functions are grouped by "topic". Where as the former naming, functions are grouped Action-Noun, but are sorted by Noun. I thought this was an interesting POV, what do other people think about naming functions/methods Topic-Comment? Obviously, mixing naming conventions up in the same project would be weird, but overall? -daniel

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• git-svn: reset tracking for master

  - by digitala

  I'm using git-svn to work with an SVN repository. My working copies have been created using git svn clone -s http://foo.bar/myproject so that my working copy follows the default directory scheme for SVN (trunk, tags, branches). Recently I've been working on a branch which was created using git-svn branch myremotebranch and checked-out using git checkout --track -b mybranch myremotebranch. I needed to work from multiple locations, so from the branch I git-svn dcommit-ed files to the SVN repository quite regularly. After finishing my changes, I switched back to the master and executed a merge, committed the merge, and tried to dcommit the successful merge to the remote trunk. It seems as though after the merge the remote tracking for the master has switched to the branch I was working on: # git checkout master # git merge mybranch ... (successful) # git add . # git commit -m '...' # git svn dcommit Committing to http://foo.bar/myproject/branches/myremotebranch ... # Is there a way I can update the master so that it's following remotes/trunk as before the merge? I'm using git 1.7.0.5, if that's any help.

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• How to create a "Shell IDList Array" to support drag-and-drop of virtual files from C# to Windows Ex

  - by JustABill

  I started trying to implement drag-and-drop of virtual files (from a C# 4/WPF app) with this codeplex tutorial. After spending some time trying to figure out a DV_E_FORMATETC error, I figured out I need to support the "Shell IDList Array" data format. But there seems to be next to zero documentation on what this format actually does. After some searching, I found this page on advanced data transfer which said that a Shell IDList Array was a pointer to a CIDA structure. This CIDA structure then contains the number of PIDLs, and a list of offsets to them. So what the hell is a PIDL? After some more searching, this page sort of implies it's a pointer to an ITEMIDLIST, which itself contains a single member that is a list of SHITEMIDs. My next idea was to try dragging a file from another application with virtual files. I just got a MemoryStream back for this format. At least I know what class to provide for the thing, but that doesn't help at all for explaining what to put in it. So now that that's explained, I still have no idea how to create one of these things so that it's valid. There's two real questions here: What is a valid "abID" member for a SHITEMID? These virtual files only exist with my program; will the thing they are dragged to pass the "abID" back later when it executes GetData? Do they have to be system-unique? Why are there two levels of lists; a list of PIDLs and each PIDL has a list of SHITEMIDs? I'm assuming one of them is one for each file, but what's the other one for? Multiple IDs for the same file? Any help or even links that explain what I should be doing would be greatly appreciated.

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• Total row count for pagination using JPA Criteria API

  - by ThinkFloyd

  I am implementing "Advanced Search" kind of functionality for an Entity in my system such that user can search that entity using multiple conditions(eq,ne,gt,lt,like etc) on attributes of this entity. I am using JPA's Criteria API to dynamically generate the Criteria query and then using setFirstResult() & setMaxResults() to support pagination. All was fine till this point but now I want to show total number of results on results grid but I did not see a straight forward way to get total count of Criteria query. This is how my code looks like: CriteriaBuilder builder = em.getCriteriaBuilder(); CriteriaQuery<Brand> cQuery = builder.createQuery(Brand.class); Root<Brand> from = cQuery.from(Brand.class); CriteriaQuery<Brand> select = cQuery.select(from); . . //Created many predicates and added to **Predicate[] pArray** . . select.where(pArray); // Added orderBy clause TypedQuery typedQuery = em.createQuery(select); typedQuery.setFirstResult(startIndex); typedQuery.setMaxResults(pageSize); List resultList = typedQuery.getResultList(); My result set could be big so I don't want to load my entities for count query, so tell me efficient way to get total count like rowCount() method on Criteria (I think its there in Hibernate's Criteria).

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• Using boost asio for pub/sub style tcp in a game loop

  - by unohoo

  I have been reading through the boost asio documentation for a couple of hours now, and while I think the documentation is really great, I am still left a bit confused on how to implement the system that I need. I have to stream info, from a game engine, to a list of computers over tcp. One snag is that, unlike traditional pub/sub, the computer that does the distribution of info is actually the computer that has to connect to the subscribers as well (instead of the subscribers registering with the publisher). This is done via a config file - a list of ip's/ports along with the data that they each require. The subscribers listen, but do not know the ip of the publisher. (As a side note, I'm quite new to network programming, so maybe I'm missing something .. but it's strange that I do not find much information regarding this style of "inverted" client-server model..) I am looking for suggestions for the implementation of such a system using boost asio. Of course I have to integrate the networking into an already existing engine, so with regards to that: What would be a good way to handle messages being sent to multiple computers every frame? Use async_write, call io_service.run and then reset every frame? Would having io_service.run have its own thread be better? Or should I just use threads and use blocking writes?

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• SQL query recursion for a web-like structure

  - by MickeyD

  I have a table here, named "Foo". The data is set up something like this. ID TableReference DataId0 DataId1 DataId2 -- -------------- ------- ------- ------- 1 Prize 3 4 5 2 Prize 4 5 NULL 3 Cash 1 NULL NULL 4 Prize 8 NULL 12 5 Foo 2 3 NULL 6 Cash 8 1 10 7 Foo 5 1 2 Etc. The data is horribly set up, I know, but I didn't set it up that way. :) I'm only dealing with the after effect. I'm trying to come up with a way to essentially "flatten" the table; that is, to display all the data to a point where the table "Foo" does not reference itself. I'm trying to figure out a sql query that I can do to get there. Usually when I deal with recursion, I have (or can establish) parent IDs and set it up that way, but for this table there are seemingly multiple child and parent IDs creating a web-like structure instead of a hierarchy. So I'm at a loss where to even begin to write a sql query for something like this. Note: There is no infinite looping (where one Foo points to another Foo, which points back to the original Foo) from what I've found. Using t-sql. Thanks for any assistance, if at all possible.

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• Trying to draw a dynamic rectangle in SVG

  - by Shaun

  To be more specific, here are the steps I need: onmousedown - set x and y of rect as mouse coordinates onmousemove - using the current x and y mouse coordinates calculate height and width of the rect, set these and append onmouseup - remove the rectangle, and call a function based off some calculations from the rect. Here is what I have but isn't quite working (right now I have it drawing a line to make it simpler): onmousedown: startbox(evt) function startbox(evt) { if(evt.button === 0) { x1 = evt.clientX + div.scrollLeft-5; y1 = evt.clientY + div.scrollTop-30; obj.setAttributeNS(null, "x1", x1); obj.setAttributeNS(null, "y1", y1); Root.setAttributeNS(null, "onmousemove", "updatebox(evt)"); } } onmousemove: updatebox(evt) function updatebox(evt) { if(evt.button === 0) { x2 = evt.clientX + div.scrollLeft-5; y2 = evt.clientY + div.scrollTop-30; Root.appendChild(.obj); w = Math.abs(x2-x1); h = Math.abs(y2-y1); var strokecolor; if(w>20 && h>20) { strokecolor = "green"; validbox = true; } else { strokecolor = "red"; validbox = false; } var Attr={ x2:x2, y2:y2, stroke:strokecolor } assignAttr(obj, Attr); //just loops thru adding multiple attributes } } onmouseup: endbox() function endbox(evt) { if(evt.button===0) { Root.setAttributeNS(null, "onmousemove", ""); Root.removeChild(obj); if(validbox) { //do stuff validbox = !validbox; } } } Some of my problems with this are: Its slow in Chrome making drawing the line/rect feel sluggish. It won't work two times in a row. This is the real problem that I can't fix. Any and all feedback is welcome.

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• How do I find and open a file in a Visual Studio 2005 add-in?

  - by Charles Randall

  I'm making an add-in with Visual Studio 2005 C# to help easily toggle between source and header files, as well as script files that all follow a similar naming structure. However, the directory structure has all of the files in different places, even though they are all in the same project. I've got almost all the pieces in place, but I can't figure out how to find and open a file in the solution based only on the file name alone. So I know I'm coming from, say, c:\code\project\subproject\src\blah.cpp, and I want to open c:\code\project\subproject\inc\blah.h, but I don't necessarily know where blah.h is. I could hardcode different directory paths but then the utility isn't generic enough to be robust. The solution has multiple projects, which seems to be a bit of a pain as well. I'm thinking at this point that I'll have to iterate through every project, and iterate through every project item, to see if the particular file is there, and then get a proper reference to it. But it seems to me there must be an easier way of doing this.

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• Pthread-ed filetransfer application crash

  - by N.R.S.Sowrabh

  I am developing a file transfer application and am using pthreads on the receiver side for receiving multiple files. The function which is passed to pthreads calls the following function and at the end of this function I get a SIGABRT error and stack-smashing error appears on the terminal. Please help me find the bugs. If you need anymore code I'd be able to post the same. Thanks in advance. void recv_mesg(int new_sockid, char *fname) { cout<<"New Thread created with "<<new_sockid<<" and "<<fname<<endl; char buf[MAXLINE]; int fd; fd = open(fname, O_WRONLY ); int len =0; while (len<1024) { int curr = recv(new_sockid, buf, 1024-len, 0); //fprintf(stdout,"Message from Client:\n"); len += curr; //write (fd, buf, curr); fputs(buf, stderr); } int file_size = 0; sscanf(buf,"%d",&file_size); if(file_size<=0) perror("File Size < 0"); sprintf(buf,"Yes"); send(new_sockid,buf,strlen(buf),0); len = 0; while (len<file_size) { int curr = recv(new_sockid, buf, min(file_size-len,MAXLINE), 0); len += curr; write (fd, buf, curr); //fputs(buf, stdout); //fflush(stdout); } len = 0; close(fd); close(new_sockid); }

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• Upgrade .NET 1.1 WinForm/Service to what?

  - by Conor

  Hi Folks, We have a current WinForm/Windows Service running in .NET 1.1 out on various customer sites that is getting data from internal systems, transforming it and then calling a Web Service synchronously. This client app will no longer work in Vista or Windows 7 etc.. and its time to update!! I was looking for ideas on what I could do here, I didn't write the App and I have the Business team telling me they want the world but I need to be realistic :) Things the service must be able to do: - Handle multiple formats from internal system and transform to a schema SAP, ERP etc.. - Run silently and just work on customer sites (it does currently albeit .NET 1.1) - The Customers are unable to call our web service from their sites as they are not technical enough. - Upgrade it's self when updates occur (currently don't have this capability) Is there anything I can do here other than upgrade the service to run in .NET and add a few more transformation capabilities e..g they want the customer to be able to give us a flat file, an xml file, a csv and the service transforms it and calls the Web Service? I was hoping in this day and age we could use the Web, but automating this 100% rules it out in my eyes? I could be totally wrong!! Any help would be gratefully appreciated! Cheers. Conor

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• ASP .NET, Javascript, AjaxControlToolkit render results with Selenium?

  - by Seth

  I'm a newbie to web stuff. However, I wish to scrape some data from multiple websites. I'm currently using the following technologies: Selenium; Python; and BeautifulSoup; I believe the site I am trying to scrape is using a combination of ASP.NET, javascript and the AjaxControlToolkit. I believe the key results I am looking for are in the following script: <script type="text/javascript"> //<![CDATA[ Sys.Application.initialize(); Sys.Application.add_init(function() { $create(AjaxControlToolkit.AutoCompleteBehavior, {"completionInterval":50,"completionListCssClass":"autocomplete_completionListElement","completionListItemCssClass":"autocomplete_listItem","completionSetCount":20,"delimiterCharacters":"","highlightedItemCssClass":"autocomplete_highlightedListItem","id":"ctl00_ContentPlaceHolder1_AutoCompleteExtender1","minimumPrefixLength":4,"serviceMethod":"GetSchoolNames","servicePath":"AutoComplete.asmx"}, {"itemSelected":ItemSelected}, null, $get("ctl00_ContentPlaceHolder1_SchoolNameTextBox")); }); Sys.Application.add_init(function() { $create(AjaxControlToolkit.AutoCompleteBehavior, {"completionInterval":50,"completionListCssClass":"autocomplete_completionListElement","completionListItemCssClass":"autocomplete_listItem","delimiterCharacters":"","highlightedItemCssClass":"autocomplete_highlightedListItem","id":"ctl00_ContentPlaceHolder1_AutoCompleteExtender2","minimumPrefixLength":2,"serviceMethod":"GetSuburbNames","servicePath":"AutoComplete.asmx"}, null, null, $get("ctl00_ContentPlaceHolder1_SuburbTownTextBox")); }); //]]> </script> Is there an easy way to get the results of the above script processed using Selenium so that I may pass it using BeautifulSoup?

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• iphone: cross platform references and referencing external framework resources

  - by dan

  hi there working on an iphone app and separate framework. the separate framework is for an API that i'm building for use in multiple future apps. this api now needs to reference resources (images). what i would like to do is keep the resources WITH the API framework as local set of resources. i followed the instructions from http://www.clintharris.net/2009/iphone-app-shared-libraries/ to setup my app's project to use the headers from the separate API framework. what i can't seem to figure out is how to automatically load the framework's resources into the app's xcode environment so they can be linked in at app compile time. sure, i can drag the resources across from the framework into the main app's set of resources. but that seems kinda ugly and another step that possibly can be automated (??) anyone know of a better way? it would be great if any changes from the framework would be automatically available in the main app (due to the project 'link-age'). thanks for any help/tips/suggestions...

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• Using SQL dB column as a lock for concurrent operations in Entity Framework

  - by Sid

  We have a long running user operation that is handled by a pool of worker processes. Data input and output is from Azure SQL. The master Azure SQL table structure columns are approximated to [UserId, col1, col2, ... , col N, beingProcessed, lastTimeProcessed ] beingProcessed is boolean and lastTimeProcessed is DateTime. The logic in every worker role is: public void WorkerRoleMain() { while(true) { try { dbContext db = new dbContext(); // Read foreach (UserProfile user in db.UserProfile .Where(u => DateTime.UtcNow.Subtract(u.lastTimeProcessed) > TimeSpan.FromHours(24) & u.beingProcessed == false)) { user.beingProcessed = true; // Modify db.SaveChanges(); // Write // Do some long drawn processing here ... ... ... user.lastTimeProcessed = DateTime.UtcNow; user.beingProcessed = false; db.SaveChanges(); } } catch(Exception ex) { LogException(ex); Sleep(TimeSpan.FromMinutes(5)); } } // while () } With multiple workers processing as above (each with their own Entity Framework layer), in essence beingProcessed is being used a lock for MutEx purposes Question: How can I deal with concurrency issues on the beingProcessed "lock" itself based on the above load? I think read-modify-write operation on the beingProcessed needs to be atomic but I'm open to other strategies. Open to other code refinements too.

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• Need help with Layouts in Swing

  - by Malki

  Hi, I'm using Java Swing and I have the following problem: I have a class TnaiPanel that extends JPanel. In this class I am creating 3 components and then lay them out in a horizontal line using a BoxLayout. Also, I have a class TnaimDinamimPanel that also extends JPanel. This class contains multiple occurances of TnaiPanel, layed out vertically using a BoxLayout. Also, I have a class MainFrame that extends JFrame. This frame contains a menu-bar and one main panel. The main panel can change (when choosing a certain menu-item, I create a new panel and set it to show as the main panel of the frame). Now, for some reason I get "BoxLayout can't be shared" when I add the newly created TnaimDinamimPanel to the components of the frame. I don't mind using different layout objects. The result I want to get is a sort of "table" of components, where each TnaiPanel will have fixed component sizes and spacing, essentially serving the role os a "row" in the "table". Thanks, Malki.

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• Flag bit computation and detection

  - by Majid

  Hi all, In some code I'm working on I should take care of ten independent parameters which can take one of two values (0 or 1). This creates 2^10 distinct conditions. Some of the conditions never occur and can be left out, but those which do occur are still A LOT and making a switch to handle all cases is insane. I want to use 10 if statements instead of a huge switch. For this I know I should use flag bits, or rather flag bytes as the language is javascript and its easier to work with a 10 byte string with to represent a 10-bit binary. Now, my problem is, I don't know how to implement this. I have seen this used in APIs where multiple-selectable options are exposed with numbers 1, 2, 4, 8, ... , n^(n-1) which are decimal equivalents of 1, 10, 100, 1000, etc. in binary. So if we make call like bar = foo(7), bar will be an object with whatever options the three rightmost flags enable. I can convert the decimal number into binary and in each if statement check to see if the corresponding digit is set or not. But I wonder, is there a way to determine the n-th digit of a decimal number is zero or one in binary form, without actually doing the conversion?

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• Any merit to a lazy-ish juxt function?

  - by NielsK

  In answering a question about a function that maps over multiple functions with the same arguments (A: juxt), I came up with a function that basically took the same form as juxt, but used map: (defn could-be-lazy-juxt [& funs] (fn [& args] (map #(apply %1 %2) funs (repeat args)))) => ((juxt inc dec str) 1) [2 0 "1"] => ((could-be-lazy-juxt inc dec str) 1) (2 0 "1") => ((juxt * / -) 6 2) [12 3 4] => ((could-be-lazy-juxt * / -) 6 2) (12 3 4) As posted in the original question, I have little clue about the laziness or performance of it, but timing in the REPL does suggest something lazy-ish is going on. => (time (apply (juxt + -) (range 1 100))) "Elapsed time: 0.097198 msecs" [4950 -4948] => (time (apply (could-be-lazy-juxt + -) (range 1 100))) "Elapsed time: 0.074558 msecs" (4950 -4948) => (time (apply (juxt + -) (range 10000000))) "Elapsed time: 1019.317913 msecs" [49999995000000 -49999995000000] => (time (apply (could-be-lazy-juxt + -) (range 10000000))) "Elapsed time: 0.070332 msecs" (49999995000000 -49999995000000) I'm sure this function is not really that quick (the print of the outcome 'feels' about as long in both). Doing a 'take x' on the function only limits the amount of functions evaluated, which probably is limited in it's applicability, and limiting the other parameters by 'take' should be just as lazy in normal juxt. Is this juxt really lazy ? Would a lazy juxt bring anything useful to the table, for instance as a compositing step between other lazy functions ? What are the performance (mem / cpu / object count / compilation) implications ? Is that why the Clojure juxt implementation is done with a reduce and returns a vector ? Edit: Somehow things can always be done simpler in Clojure. (defn could-be-lazy-juxt [& funs] (fn [& args] (map #(apply % args) funs)))

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• Use queried json data in a function

  - by SztupY

  I have a code similar to this: $.ajax({ success: function(data) { text = ''; for (var i = 0; i< data.length; i++) { text = text + '<a href="#" id="Data_'+ i +'">' + data[i].Name + "</a><br />"; } $("#SomeId").html(text); for (var i = 0; i< data.length; i++) { $("#Data_"+i).click(function() { alert(data[i]); RunFunction(data[i]); return false; }); } } }); This gets an array of some data in json format, then iterates through this array generating a link for each entry. Now I want to add a function for each link that will run a function that does something with this data. The problem is that the data seems to be unavailable after the ajax success function is called (although I thought that they behave like closures). What is the best way to use the queried json data later on? (I think setting it as a global variable would do the job, but I want to avoid that, mainly because this ajax request might be called multiple times) Thanks.

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• Technology and language for a stable Digital Audio Workstation development

  - by Kill KRT

  Hi, I'm designing a cross platform (Windows/Linux/OS X) application, something like a digital audio workstation. I'd like to create a software where users have a fully featured sequencer (multiple tracks with automation) and where it is possible to create instruments using a visual language (as Pure Data/Max MSP). Ehm... I know that I've already posted a question about a related issue... But in order to decide which technology I should use, I think I'd better to make more investigation. I'm a quite experted user of audio trackers (Renoise, Protracker,...) and sequencers (FL Studio, Cubase 5), but I didn't ever try to develop even a basic audio tracker. I know just the basic theory of mixing sound and know how basically a DSP works. My questions are: Where I can find a good tutorial/guide/book about this issue? Do you think using C# (with NAudio) could dramatically reduce performance? I know C++ would be the best choice, but I find C# so elegant and easy to build and port, while C++ is so powerful and fast, but there are too #define and bad things for my taste! ;-) Thank you.

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• SQL 2 INNER JOINS with 3 tables

  - by Jelmer Holtes

  I've a question about a SQL query.. I'm building a prototype webshop in ASP.NET Visual Studio. Now I'm looking for a solution to view my products. I've build a database in MS Access, it consists of multiple tables. The tables which are important for my question are: Product Productfoto Foto Below you'll see the relations between the tables For me it is important to get three datatypes: Product title, price and image. The product title, and the price are in the Product table. The images are in the Foto table. Because a product can have more than one picture, there is a N - M relation between them. So I've to split it up, I did it in the Productfoto table. So the connection between them is: product.artikelnummer -> productfoto.artikelnummer productfoto.foto_id -> foto.foto_id Then I can read the filename (in the database: foto.bestandnaam) I've created the first inner join, and tested it in Access, this works: SELECT titel, prijs, foto_id FROM Product INNER JOIN Productfoto ON product.artikelnummer = productfoto.artikelnummer But I need another INNER JOIN, how could I create that? I guess something like this (this one will give me an error) SELECT titel, prijs, bestandnaam FROM Product (( INNER JOIN Productfoto ON product.artikelnummer = productfoto.artikkelnummer ) INNER JOIN foto ON productfoto.foto_id = foto.foto_id) Can anyone help me?

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• looping through JSON array

  - by Phil Jackson

  Hi all. I have recently posted another question which straight away users pointed me in the right direction. $.ajax({ type: 'POST', url: './', data: 'token=' + token + '&re=8', cache: false, timeout: 5000, success: function(html){ auth(html); var JSON_array = eval(html); alert(JSON_array[0].username); } }); this returns the data correctly but I want to perform a kind of 'foreach'. the array contains data about multiple incoming and outgoing Instant Messages. So if a user is talking to more than one person at a time i need to loop through. the array's structure is as follows. Array ( [0] => Array ( [username] => Emmalene [contents] => <ul><li class="name">ACTwebDesigns</li><li class="speech">helllllllo</li></ul> <ul><li class="name">ACTwebDesigns</li><li class="speech">sds</li></ul> <ul><li class="name">ACTwebDesigns</li><li class="speech">Sponge</li><li class="speech">dick</li></ul> <ul><li class="name">ACTwebDesigns</li><li class="speech">arghh</li></ul> ) ) any help very much appreciated.

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• Should java try blocks be scoped as tightly as possible?

  - by isme

  I've been told that there is some overhead in using the Java try-catch mechanism. So, while it is necessary to put methods that throw checked exception within a try block to handle the possible exception, it is good practice performance-wise to limit the size of the try block to contain only those operations that could throw exceptions. I'm not so sure that this is a sensible conclusion. Consider the two implementations below of a function that processes a specified text file. Even if it is true that the first one incurs some unnecessary overhead, I find it much easier to follow. It is less clear where exactly the exceptions come from just from looking at statements, but the comments clearly show which statements are responsible. The second one is much longer and complicated than the first. In particular, the nice line-reading idiom of the first has to be mangled to fit the readLine call into a try block. What is the best practice for handling exceptions in a funcion where multiple exceptions could be thrown in its definition? This one contains all the processing code within the try block: void processFile(File f) { try { // construction of FileReader can throw FileNotFoundException BufferedReader in = new BufferedReader(new FileReader(f)); // call of readLine can throw IOException String line; while ((line = in.readLine()) != null) { process(line); } } catch (FileNotFoundException ex) { handle(ex); } catch (IOException ex) { handle(ex); } } This one contains only the methods that throw exceptions within try blocks: void processFile(File f) { FileReader reader; try { reader = new FileReader(f); } catch (FileNotFoundException ex) { handle(ex); return; } BufferedReader in = new BufferedReader(reader); String line; while (true) { try { line = in.readLine(); } catch (IOException ex) { handle(ex); break; } if (line == null) { break; } process(line); } }

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• Parsing a JSON feed from YQL using jQuery

  - by Keith

  I am using YQL's query.multi to grab multiple feeds so I can parse a single JSON feed with jQuery and reduce the number of connections I'm making. In order to parse a single feed, I need to be able to check the type of result (photo, item, entry, etc) so I can pull out items in specific ways. Because of the way the items are nested within the JSON feed, I'm not sure the best way to loop through the results and check the type and then loop through the items to display them. Here is a YQL (http://developer.yahoo.com/yql/console/) query.multi example and you can see three different result types (entry, photo, and item) and then the items nested within them: select * from query.multi where queries= "select * from twitter.user.timeline where id='twitter'; select * from flickr.photos.search where has_geo='true' and text='san francisco'; select * from delicious.feeds.popular" or here is the JSON feed itself: http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20query.multi%20where%20queries%3D%22select%20*%20from%20flickr.photos.search%20where%20user_id%3D'23433895%40N00'%3Bselect%20*%20from%20delicious.feeds%20where%20username%3D'keith.muth'%3Bselect%20*%20from%20twitter.user.timeline%20where%20id%3D'keithmuth'%22&format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys&callback=

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