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  • SWIG interface to receive an opaque struct reference in Java through function argument

    - by Beeo
    I am trying to use SWIG in order to use the Spotify API (libspotify) for Android: https://developer.spotify.com/technologies/libspotify/ I am having trouble defining the SWIG interface file to be able to successfully call the following native C function: sp_error sp_session_create(const sp_session_config * config, sp_session ** sess); Which in C would be called like this: //config struct defined previously sp_session *sess; sp_session_create(&config, &sess); But in Java I would need to call it like this: //config object defined previously sp_session javaSess = new sp_session(); sp_session_create(config, javaSess); sp_session is an opaque struct and is only defined in libspotify's API.h file as: typedef struct sp_session sp_session; I'm expecting the libspotify library to create it and give me a reference to it. The only thing I need that reference for then is to pass to other functions in the API. I believe the answer lies within the SWIG interface and typemaps, but I have been unsuccessful in trying to apply the examples I found in the documentation: http://www.swig.org/Doc2.0/SWIGDocumentation.html#Java_struct_pointer_pointer `http://www.swig.org/Doc2.0/SWIGDocumentation.html#Java_using_typemaps_return_arguments Help!

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  • Extracting function declarations from a PHP file

    - by byronh
    I'm looking to create an on-site API reference for my framework and application. Basically, say I have a class file model.class.php: class Model extends Object { ... code here ... // Separates results into pages. // Returns Paginator object. final public function paginate($perpage = 10) { ... more code here ... } } and I want to be able to generate a reference that my developers can refer to quickly in order to know which functions are available to be called. They only need to see the comments directly above each function and the declaration line. Something like this (similar to a C++ header file): // Separates results into pages. // Returns Paginator object. final public function paginate($perpage = 10); I've done some research and this answer looked pretty good (using Reflection classes), however, I'm not sure how I can keep the comments in. Any ideas? EDIT: Sorry, but I want to keep the current comment formatting. Myself and the people who are working on the code hate the verbosity associated with PHPDocumentor. Not to mention a comment-rewrite of the entire project would take years, so I want to preserve just the // comments in plaintext.

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  • UITableView UITableViewCell dynamic UILabel Height storyboard

    - by Mikel Nelson
    This isn'an a question, just a results log on an issue I had with XCode 4.5 storyboards and dynamic height UITableCell with a UILabel. The issue was; the initial display of a cell would only show part of the resized UILabel contents, and that the visual UILabel was not resized. It would only display correctly after scrolling off the top of the Table and back down. I did the calculations in hieghtForRowAtIndexPath and sizeToFit the UILabel in rowAtIndexPath. The sizes where coming up ok in debug, but the device was not updating the display with the correct size and UILable.text value. I had created the dynamic UITableCell in a storyboard. However, I had set the width and height to a nominal value (290x44). It turns out, this was causing my issues. I set the width and height to zero (0) in the story board, and everything started working correctly. (i.e. the UILabels displayed at the correct size with full content). I was unable to find anything online on this issue, except for some references to creating the custom table cell with a frame of zero. Turns out, that was really the answer (for me).

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  • how does Cocoa compare to Microsoft, Qt?

    - by Paperflyer
    I have done a few months of development with Qt (built GUI programatically only) and am now starting to work with Cocoa. I have to say, I love Cocoa. A lot of the things that seemed hard in Qt are easy with Cocoa. Obj-C seems to be far less complex than C++. This is probably just me, so: Ho do you feel about this? How does Cocoa compare to WPF (is that the right framework?) to Qt? How does Obj-C compare to C# to C++? How does XCode/Interface Builder compare to Visual Studio to Qt Creator? How do the Documentations compare? For example, I find Cocoa's Outlets/Actions far more useful than Qt's Signals and Slots because they actually seem to cover most GUI interactions while I had to work around Signals/Slots half the time. (Did I just use them wrong?) Also, the standard templates of XCode give me copy/paste, undo/redo, save/open and a lot of other stuff practically for free while these were rather complex tasks in Qt. Please only answer if you have actual knowledge of at least two of these development environments/frameworks/languages.

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  • How to reduce the need for IISRESET for developing ASP.NET web app in IIS 5.1

    - by John Galt
    I have a web application project on my dev PC running WinXP and hence IIS 5.1. The changes I'm making to this site seem to "take effect" only after I do IISRESET. That is, I make a source change, Rebuild the project and then Start without Debugging (or with debugging). The newly changed code is not "visible" or in effect unless I intervene with an IISRESET. BTW, the "web" tab on the Properties display for the web app project is configured to use the Local IIS web server at project Url: http://localhost/myVirtualDirectory ... but I've noticed the same issue when using the VStudio Dev Server (i.e. I have to stop it by visiting the taskbar tray area in order to see my source changes take effect). Is this something I can change? EDIT UPDATE: Just wanting to clear this up if possible. Two answers diverge below; not sure how to move forward. One states this is to be expected (weakness of IIS 5.1 which in turn is the best WinXP can provide). Another states this is not expected behavior (and I tend to agree since this is the first I've encounted this on the same old WinXP dev platform I've had a long time). I suspect it may be something "deep inside" the Visual Studio 2008 web app which was upgraded to this new IDE from VStudio 2002 (ASP.NET 1.1). I've tried to add comment/questions down each answer path. Thanks.

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  • 503 server response for Googlebot

    - by Hallik
    I put an .htaccess file in my webroot with the following contents RewriteBase / RewriteCond %{HTTP_USER_AGENT} ^.*(Googlebot|Googlebot|Mediapartners|Adsbot|Feedfetcher)-?(Google|Image)? [NC] RewriteRule .* /var/www/503.html This website is in maintenance mode, and I don't want anything indexed yet. I tested the code with a firefox User-Agent switcher plugin, and looking at the access log it shows this at the end of each log entry, but watching in TamperData or Firebug, it still returns a 200 server response instead of a 503. What am I doing wrong? "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" contents of /var/www/503.html <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2//EN"> <html> <head> <title>503 - Service temporary unavailable</title> </head> <body> <h1>503 - Service temporary unavailable</h1> <p>Sorry, this website is currently down for maintainance please retry later</p> </body> </html> I get this in my error log. LogLevel debug, would that go into the vhost in a specific place? Every answer I see on google is something different. Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.

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  • Will my LinqToSql execution be deffered if i filter with IEnumerable<T> instead of IQueryable<T>?

    - by cottsak
    I have been using these common EntityObjectFilters as a "pipes and filters" way to query from a collection a particular item with an ID: public static class EntityObjectFilters { public static T WithID<T>(this IQueryable<T> qry, int ID) where T : IEntityObject { return qry.SingleOrDefault<T>(item => item.ID == ID); } public static T WithID<T>(this IList<T> list, int ID) where T : IEntityObject { return list.SingleOrDefault<T>(item => item.ID == ID); } } ..but i wondered to myself: "can i make this simpler by just creating an extension for all IEnumerable<T> types"? So i came up with this: public static class EntityObjectFilters { public static T WithID<T>(this IEnumerable<T> qry, int ID) where T : IEntityObject { return qry.SingleOrDefault<T>(item => item.ID == ID); } } Now while this appears to yield the same result, i want to know that when applied to IQueryable<T>s will the expression tree be passed to LinqToSql for evaluating as SQL code or will my qry be evaluated in it's entirety first, then iterated with Funcs? I'm suspecting that (as per Richard's answer) the latter will be true which is obviously what i don't want. I want the same result, but the added benefit of the delayed SQL execution for IQueryable<T>s. Can someone confirm for me what will actually happen and provide simple explanation as to how it would work?

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  • Serializing Configurations for a Dependency Injection / Inversion of Control

    - by Joshua Starner
    I've been researching Dependency Injection and Inversion of Control practices lately in an effort to improve the architecture of our application framework and I can't seem to find a good answer to this question. It's very likely that I have my terminology confused, mixed up, or that I'm just naive to the concept right now, so any links or clarification would be appreciated. Many examples of DI and IoC containers don't illustrate how the container will connect things together when you have a "library" of possible "plugins", or how to "serialize" a given configuration. (From what I've read about MEF, having multiple declarations of [Export] for the same type will not work if your object only requires 1 [Import]). Maybe that's a different pattern or I'm blinded by my current way of thinking. Here's some code for an example reference: public abstract class Engine { } public class FastEngine : Engine { } public class MediumEngine : Engine { } public class SlowEngine : Engine { } public class Car { public Car(Engine e) { engine = e; } private Engine engine; } This post talks about "Fine-grained context" where 2 instances of the same object need different implementations of the "Engine" class: http://stackoverflow.com/questions/2176833/ioc-resolve-vs-constructor-injection Is there a good framework that helps you configure or serialize a configuration to achieve something like this without hard coding it or hand-rolling the code to do this? public class Application { public void Go() { Car c1 = new Car(new FastEngine()); Car c2 = new Car(new SlowEngine()); } } Sample XML: <XML> <Cars> <Car name="c1" engine="FastEngine" /> <Car name="c2" engine="SlowEngine" /> </Cars> </XML>

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  • Five unique, random numbers from a subset

    - by tau
    I know similar questions come up a lot and there's probably no definitive answer, but I want to generate five unique random numbers from a subset of numbers that is potentially infinite (maybe 0-20, or 0-1,000,000). The only catch is that I don't want to have to run while loops or fill an array. My current method is to simply generate five random numbers from a subset minus the last five numbers. If any of the numbers match each other, then they go to their respective place at the end of the subset. So if the fourth number matches any other number, it will bet set to the 4th from the last number. Does anyone have a method that is "random enough" and doesn't involve costly loops or arrays? Please keep in mind this a curiosity, not some mission-critical problem. I would appreciate it if everyone didn't post "why are you having this problem?" answers. I am just looking for ideas. Thanks a lot!

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  • Global javascript variable not accessible in jquery change event

    - by Dan
    I have to be missing something simple, but I'm really not sure what. I'm not a JS veteran, so this may be an easy answer - sure hope so :). I have a button that, when clicked, gets JSON data. When a drop-down is changed, I check to see if there is data, if there is, I want to clear it out as the drop-down indicates what data to retrieve when the button is clicked The Code: var selected, $locDialog; var locations = []; $(function() { // Save the selected Name selected = $("#selected option:selected").val(); // Setup Dialog for Locations $locDialog = $('#location-dialog').dialog({ autoOpen: false }); // If user changes the selected // 1. Prompt for confirmation // 2. If users confirms, clear data $('#selected').change(function() { if (locations) { var confirmed = confirm("Oh Rly?"); if (confirmed) { // Clear data var locations; } } }); // When user clicks "Location" Button.. $('.loc-select button').click(function() { if (!locations) { $.getJSON("/Controller/JSONAction", { selectedId: selected, pageNum: 1, pageSize: 100 }, function(data) { locations = data; $.each(locations, function(index, loc) { var $tr = $('<tr/>') .append($('<td/>') .append('<input type="checkbox" name="TEST-'+index+'" value="'+loc.Id+'"/>')) .append('<td>' + loc.Name + '</td>'); $("#location-dialog table tbody").append($tr); }); }); } $locDialog.dialog('open'); return false; }); }); Here's the thing, Inside the .click(...) callback, I can see locations is []. Now, when I am in the .change(...) callback, I see locations is undefined. Any help/insight, as always, is appreciated!

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  • How can I execute an ANTLR parser action for each item in a rule that can match more than one item?

    - by Chris Farmer
    I am trying to write an ANTLR parser rule that matches a list of things, and I want to write a parser action that can deal with each item in the list independently. Some example input for these rules is: $(A1 A2 A3) I'd like this to result in an evaluator that contains a list of three MyIdentEvaluator objects -- one for each of A1, A2, and A3. Here's a snippet of my grammar: my_list returns [IEvaluator e] : { $e = new MyListEvaluator(); } '$' LPAREN op=my_ident+ { /* want to do something here for each 'my_ident'. */ /* the following seems to see only the 'A3' my_ident */ $e.Add($op.e); } RPAREN ; my_ident returns [IEvaluator e] : IDENT { $e = new MyIdentEvaluator($IDENT.text); } ; I think my_ident is defined correctly, because I can see the three MyIdentEvaluators getting created as expected for my input string, but only the last my_ident ever gets added to the list (A3 in my example input). How can I best treat each of these elements independently, either through a grammar change or a parser action change? It also occurred to me that my vocabulary for these concepts is not what it should be, so if it looks like I'm misusing a term, I probably am. EDIT in response to Wayne's comment: I tried to use op+=my_ident+. In that case, the $op in my action becomes an IList (in C#) that contains Antlr.Runtime.Tree.CommonTree instances. It does give me one entry per matched token in $op, so I see my three matches, but I don't have the MyIdentEvaluator instances that I really want. I was hoping I could then find a rule attribute in the ANTLR docs that might help with this, but nothing seemed to help me get rid of this IList. Result... Based on chollida's answer, I ended up with this which works well: my_list returns [IEvaluator e] : { $e = new MyListEvaluator(); } '$' LPAREN (op=my_ident { $e.Add($op.e); } )+ RPAREN ; The Add method gets called for each match of my_ident.

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  • Project Euler #14 and memoization in Clojure

    - by dbyrne
    As a neophyte clojurian, it was recommended to me that I go through the Project Euler problems as a way to learn the language. Its definitely a great way to improve your skills and gain confidence. I just finished up my answer to problem #14. It works fine, but to get it running efficiently I had to implement some memoization. I couldn't use the prepackaged memoize function because of the way my code was structured, and I think it was a good experience to roll my own anyways. My question is if there is a good way to encapsulate my cache within the function itself, or if I have to define an external cache like I have done. Also, any tips to make my code more idiomatic would be appreciated. (use 'clojure.test) (def mem (atom {})) (with-test (defn chain-length ([x] (chain-length x x 0)) ([start-val x c] (if-let [e (last(find @mem x))] (let [ret (+ c e)] (swap! mem assoc start-val ret) ret) (if (<= x 1) (let [ret (+ c 1)] (swap! mem assoc start-val ret) ret) (if (even? x) (recur start-val (/ x 2) (+ c 1)) (recur start-val (+ 1 (* x 3)) (+ c 1))))))) (is (= 10 (chain-length 13)))) (with-test (defn longest-chain ([] (longest-chain 2 0 0)) ([c max start-num] (if (>= c 1000000) start-num (let [l (chain-length c)] (if (> l max) (recur (+ 1 c) l c) (recur (+ 1 c) max start-num)))))) (is (= 837799 (longest-chain))))

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  • Who's setting TCP window size down to 0, Indy or Windows?

    - by François
    We have an application server which have been observed sending headers with TCP window size 0 at times when the network had congestion (at a client's site). We would like to know if it is Indy or the underlying Windows layer that is responsible for adjusting the TCP window size down from the nominal 64K in adaptation to the available throughput. And we would be able to act upon it becoming 0 (nothing gets send, users wait = no good). So, any info, link, pointer to Indy code are welcome... Disclaimer: I'm not a network specialist. Please keep the answer understandable for the average me ;-) Note: it's Indy9/D2007 on Windows Server 2003 SP2. More gory details: The TCP zero window cases happen on the middle tier talking to the DB server. It happens at the same moments when end users complain of slowdowns in the client application (that's what triggered the network investigation). 2 major Network issues causing bottlenecks have been identified. The TCP zero window happened when there was network congestion, but may or may not be caused by it. We want to know when that happen and have a way to do something (logging at least) in our code. So where to hook (in Indy?) to know when that condition occurs?

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  • Error while compiling pjsip 2 for cxode 4.3.2 and SDK 5.1

    - by Linus Persson
    I'm trying to compile pjsip version 2 using the terminal and I'm getting constant error no matter what I try. Been looking for the answer all over the internet including stackoverflow. I downloaded pjsip version 2 using their subversion repository today so all files should be up to date. When following this guide: http://trac.pjsip.org/repos/wiki/Getting-Started/iPhone I get this error after running "make dep && make clean && make": ld: symbol(s) not found for architecture armv7 collect2: ld returned 1 exit status make[2]: *** [../bin/pjsua-arm-apple-darwin9] Error 1 make[1]: *** [pjsua] Error 2 make: *** [all] Error 1 When using the above guide combined with this guide: http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/2011-October/013481.html I get this error after running "make dep && make clean && make": ld: symbol(s) not found for architecture arm collect2: ld returned 1 exit status make[2]: *** [../bin/pjsua-arm-apple-darwin10] Error 1 make[1]: *** [pjsua] Error 2 make: *** [all] Error 1 I've included /pjlib/include/pj/config_site.h with the following code: #define PJ_CONFIG_IPHONE 1 #include <pj/config_site_sample.h> How do I get pjsip to compile without errors? Please consider that I'm new to this, thank you!

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  • MYSQL JOIN WHERE ISSUES - need some kind of if condition

    - by Breezer
    Hi Well this will be hard to explain but ill do my best The thing is i have 4 tables all with a specific column to relate to eachother. 1 table with users(agent_users) , 1 with working hours(agent_pers), 1 with sold items(agent_stat),1 with project(agent_pro) the user and the project table is irrelevant in the issue at hand but to give you a better understanding why certain tables is included in my query i decided to still mention them =) The thing is that I use 2 pages to insert data to the working hour and the sold items during that time tables, then i have a third page to summarize everything for current month, the query for that is as following: SELECT *, SUM(sv_p_kom),SUM(sv_p_gick),SUM(sv_p_lunch) FROM (( agent_users LEFT JOIN agent_pers ON agent_users.sv_aid = agent_pers.sv_p_uid) LEFT JOIN agent_stat ON agent_pers.sv_p_uid = agent_stat.sv_s_uid) LEFT JOIN agent_pro ON agent_pers.sv_p_pid=agent_pro.p_id WHERE MONTH(agent_pers.sv_p_datum) =7 GROUP BY sv_aname so the problem is now that i dont want sold items from previous months to get included in the data received, i know i could solve that by simple adding in the WHERE part MONTH(agent_stat.sv_s_datum) =7 but then if no items been sold that month no data at all will show up not the time or anything. Any aid on how i could solve this is greatly appreciated. if there's something that's not so clear dont hesitate to ask and ill try my best to answer. after all my english isn't the best out there :P regards breezer

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  • C# / Silverlight / WPF / Fast rendering lots of circles

    - by Walt W
    I want to render a lot of circles or small graphics within either silverlight or wpf (around 1000-10000) as fast and as frequently as possible. If I have to go to DX or OGL, that's fine, but I'm wondering about doing this within either of those two frameworks first (read: it's OK if an answer is WPF-only or Silverlight-only). Also, if there is a way to access DX through WPF and render on a surface that way, I would be interested in that as well. So, what's the fastest way to draw a load of circles? They can be as plain as necessary, but they do need to have a radius. Currently I'm using DrawingVisual and a DrawingContext.DrawEllipse() command for each circle, then rendering the visual to a RenderTargetBItmap, but it becomes very slow as the number of circles rises. By the way, these circles move every frame, so caching isn't really an option unless you're going to suggest caching the individual circles . . . But their sizes are dynamic, so I'm not sure that's a great approach.

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  • C# parameter count mismatch when trying to add AsyncCallback into BeginInvoke()

    - by PunX
    I have main form (PrenosForm) and I am trying to run Form2 asynchronously. It works without callback delegate: this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, null); //works 1. Doesn't work with callback delegate (parameter count mismatch): this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, new AsyncCallback(callBackDelegate), null); //doesn't work parameter count mismatch 2. Works with callback delegate if I do it like this: cp.BeginInvoke(datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt, new AsyncCallback(callBackDelegate), null); //works 3. My question is why does one way work and the other doesn't? I'm new at this. Would anyone be so kind as to answer my question and point out my mistakes? private delegate void copyDelegat(List<ListViewItem> datoteke, string path, PrenosForm forma, DragDropEffects efekt); private delegate void callBackDelegat(IAsyncResult a); public void doCopy(List<ListViewItem> datoteke, string path, PrenosForm forma, DragDropEffects efekt) { new Form2(datoteke, path, forma, efekt); } public void callBackFunc(IAsyncResult a) { AsyncResult res = a.AsyncState as AsyncResult; copyDelegat delegat = res.AsyncDelegate as copyDelegat; delegat.EndInvoke(a); } public void kopiraj(List<ListViewItem> datoteke, DragDropEffects efekt) { copyDelegat cp = new copyDelegat(doCopy); callBackDelegat callBackDelegate = new callBackDelegat(callBackFunc); this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, new AsyncCallback(callBackDelegate), null); //doesn't work parameter count missmatch 2. this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, null); //works 1. cp.BeginInvoke(datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt, new AsyncCallback(callBackDelegate), null); //works 3. }

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  • java gregorian calendar timer

    - by Ieyasu Sawada
    I have this java program which calculates the time that the person took to respond to the confirm dialog box. But it seems that both time1 and time 2 gets the same value. What have I done wrong here: import javax.swing.JOptionPane; import java.util.*; public class DialogTimer{ public static void main(String args[]){ int time1, time2, milli1, milli2, sec1, sec2, timeDifference; final int MILLISECSINSECOND =1000; JOptionPane.showConfirmDialog(null, "Is stealing ever justified? "); GregorianCalendar before=new GregorianCalendar(); GregorianCalendar after= new GregorianCalendar(); milli1=before.get(GregorianCalendar.MILLISECOND); milli2=after.get(GregorianCalendar.MILLISECOND); sec1=before.get(GregorianCalendar.SECOND); sec2=after.get(GregorianCalendar.SECOND); time1=MILLISECSINSECOND * sec1 + milli1; time2=MILLISECSINSECOND * sec2 + milli2; //timeDifference=time1 - time2; System.out.println(time1); System.out.println(time2); //JOptionPane.showMessageDialog(null, "It took " + (time1 - time2) + " milliseconds for you to answer"); } }

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  • GlassFish 3: how do you change the (default) logging format?

    - by Kawu
    The question originated from here: http://www.java.net/forum/topic/glassfish/glassfish/configuring-glassfish-logging-format - without an answer. The default GlassFish 3 logging format of is very annoying, much too long. [#|2012-03-02T09:22:03.165+0100|SEVERE|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=113;_ThreadName=AWT-EventQueue-0;| MESSAGE... ] This is just a horrible default IMO. The docs just explain all the fields, but not how to change the format: http://docs.oracle.com/cd/E18930_01/html/821-2416/abluk.html Note, that I deploy SLF4J along with my webapp which should pick up the format as well. How do you change the logging format? FYI: The links here are outdated: Install log formater in glassfish... The question here hasn't been answered: How to configure GlassFish logging to show milliseconds in timestamps?... The posting here resulted in nothing: http://www.java.net/forum/topic/glassfish/glassfish/cant-seem-configure-... It looks like GlassFish logging configuration is an issue of its own. Can anybody help?

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  • Still Confused About Identifying vs. Non-Identifying Relationships

    - by Jason
    So, I've been reading up on identifying vs. non-identifying relationships in my database design, and a number of the answers on SO seem contradicting to me. Here are the two questions I am looking at: What's the Difference Between Identifying and Non-Identifying Relationships Trouble Deciding on Identifying or Non-Identifying Relationship Looking at the top answers from each question, I appear to get two different ideas of what an identifying relationship is. The first question's response says that an identifying relationship "describes a situation in which the existence of a row in the child table depends on a row in the parent table." An example of this that is given is, "An author can write many books (1-to-n relationship), but a book cannot exist without an author." That makes sense to me. However, when I read the response to question two, I get confused as it says, "if a child identifies its parent, it is an identifying relationship." The answer then goes on to give examples such as SSN (is identifying of a Person), but an address is not (because many people can live at an address). To me, this sounds more like a case of the decision between primary key and non-primary key. My own gut feeling (and additional research on other sites) points to the first question and its response being correct. However, I wanted to verify before I continued forward as I don't want to learn something wrong as I am working to understand database design. Thanks in advance.

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  • Are .NET's regular expressions Turing complete?

    - by Robert
    Regular expressions are often pointed to as the classical example of a language that is not Turning complete. For example "regular expressions" is given in as the answer to this SO question looking for languages that are not Turing complete. In my, perhaps somewhat basic, understanding of the notion of Turning completeness, this means that regular expressions cannot be used check for patterns that are "balanced". Balanced meaning have an equal number of opening characters as closing characters. This is because to do this would require you to have some kind of state, to allow you to match the opening and closing characters. However the .NET implementation of regular expressions introduces the notion of a balanced group. This construct is designed to let you backtrack and see if a previous group was matched. This means that a .NET regular expressions: ^(?<p>a)*(?<-p>b)*(?(p)(?!))$ Could match a pattern that: ab aabb aaabbb aaaabbbb ... etc. ... Does this means .NET's regular expressions are Turing complete? Or are there other things that are missing that would be required for the language to be Turing complete?

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  • What is the correct stage to use for Google Guice in production in an application server?

    - by Yishai
    It seems like a strange question (the obvious answer would Production, duh), but if you read the java docs: /** * We want fast startup times at the expense of runtime performance and some up front error * checking. */ DEVELOPMENT, /** * We want to catch errors as early as possible and take performance hits up front. */ PRODUCTION Assuming a scenario where you have a stateless call to an application server, the initial receiving method (or there abouts) creates the injector new every call. If there all of the module bindings are not needed in a given call, then it would seem to have been better to use the Development stage (which is the default) and not take the performance hit upfront, because you may never take it at all, and here the distinction between "upfront" and "runtime performance" is kind of moot, as it is one call. Of course the downside of this would appear to be that you would lose the error checking, causing potential code paths to cause a problem by surprise. So the question boils down to are the assumptions in the above correct? Will you save performance on a large set of modules when the given lifetime of an injector is one call?

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  • Is learning C++ a good idea?

    - by chang
    The more I hear and read about C++ (e.g. this: http://lwn.net/Articles/249460/), I get the impression, that I'd waste my time learning C++. I some wrote network routing algorithm in C++ for a simulator, and it was a pain (as expected, especially coming from a perl/python/Java background ...). I'm never happy about giving up on some technology, but I would be happy, if I could limit my knowledge of C-family languages to just C, C# and Objective-C (even OS Xs Cocoa, which is huge and takes a lot of time to learn looks like joy compared to C++ ...). Do I need to consider myself dumb or unwilling, just because I'm not partial to the pain involved learning this stuff? Technologies advance and there will be options other than C++, when deciding on implementation languages, or not? And for speed: If speed were that critical, I'd go for a plain C implementation instead, or write C extensions for much more productive languages like ruby or python ... The one-line version of the above: Will C++ stay such a relevant language that every committed programmer should be familiar with it? [ edit / thank you very much for your interesting and useful answers so far .. ] [ edit / .. i am accepting the top-rated answer; thanks again for all answers! ]

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  • Gem Load Error about whois command and removed cache

    - by Puru puru rin..
    Hello, I have an awesome trouble with Gem. After executing this command: rm -f /usr/local/lib/ruby/gems/1.9.1/cache/* I can not do any thing. If I try for instance: gem cleanup I get this kind of answer: /usr/local/lib/ruby/gems/1.9.1/gems/gemwhois-0.1/lib/gemwhois.rb:3:in `require': no such file to load -- rubygems/commands/whois (LoadError) from /usr/local/lib/ruby/gems/1.9.1/gems/gemwhois-0.1/lib/gemwhois.rb:3:in `<top (required)>' from /usr/local/lib/ruby/gems/1.9.1/gems/gemwhois-0.1/lib/rubygems_plugin.rb:2:in `require' from /usr/local/lib/ruby/gems/1.9.1/gems/gemwhois-0.1/lib/rubygems_plugin.rb:2:in `<top (required)>' from /usr/local/lib/ruby/site_ruby/1.9.1/rubygems.rb:1113:in `load' from /usr/local/lib/ruby/site_ruby/1.9.1/rubygems.rb:1113:in `block in <top (required)>' from /usr/local/lib/ruby/site_ruby/1.9.1/rubygems.rb:1105:in `each' from /usr/local/lib/ruby/site_ruby/1.9.1/rubygems.rb:1105:in `<top (required)>' from <internal:gem_prelude>:235:in `require' from <internal:gem_prelude>:235:in `load_full_rubygems_library' from <internal:gem_prelude>:334:in `const_missing' from /usr/local/bin/gem:12:in `<main>' It's the same for gem -v, of just gem command... I'm working of Snow Leopard. What should the best solution about you? Thanks a lot!

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  • C# class can not disguise to be another class because GetType method cannot be override

    - by zinking
    there is a statement in the CLR via C# saying in C#, one class cannot disguise to be another, because GetType is virutal and thus it cannot be override but I think in C# we can still hide the parent implementation of GetType. I must missed something if I hide the base GetType implementation then I can disguise my class to be another class, is that correct? The key here is not whether GetType is virutal or not, the question is can we disguise one class to be another in C# Following is the NO.4 answer from the possible duplicate, so My question is more on this. is this kind of disguise possible, if so, how can we say that we can prevent class type disguise in C# ? regardless of the GetType is virtual or not While its true that you cannot override the object.GetType() method, you can use "new" to overload it completely, thereby spoofing another known type. This is interesting, however, I haven't figured out how to create an instance of the "Type" object from scratch, so the example below pretends to be another type. public class NotAString { private string m_RealString = string.Empty; public new Type GetType() { return m_RealString.GetType(); } } After creating an instance of this, (new NotAString()).GetType(), will indeed return the type for a string. share|edit|flag answered Mar 15 at 18:39 Dr Snooze 213 By almost anything that looks at GetType has an instance of object, or at the very least some base type that they control or can reason about. If you already have an instance of the most derived type then there is no need to call GetType on it. The point is as long as someone uses GetType on an object they can be sure it's the system's implementation, not any other custom definition. – Servy Mar 15 at 18:54 add comment

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