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• Examples of both beautiful and ugly java code?

  - by tputkonen

  I would like to demonstrate how difficult it is for a layman to identify high quality code from flawed code. I'm thinking of doing this with the help of two java methods. Both of the methods should look like they do the same, pretty simple thing. However one of them should have several kind of flaws, for example: iteration with array off by one error string concatenations causing lots of objects to be created (as opposed to StringBuffer in the "good" code, which looks more complicated) possibly null pointer exception (but it should not be trivial to spot) Those are just some examples, all kinds of other issues including bugs and performance related structures are highly appreciated. Methods should be around 10-20 lines of length, and the task they do should be something simple - preferably printing something in an iteration.

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• Does "Value Restriction" practically mean that there is no higher order functional programming?

  - by Sadache

  Does "Value Restriction" practically mean that there is no higher order functional programming? I have a problem that each time I try to do a bit of HOP I get caught by a VR error. Example: let simple (s:string)= fun rq->1 let oops= simple "" type 'a SimpleType= F of (int ->'a-> 'a) let get a = F(fun req -> id) let oops2= get "" and I would like to know whether it is a problem of a prticular implementation of VR or it is a general problem that has no solution in a mutable type-infered language that doesn't include mutation in the type system.

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• PHP - How to determine if request is coming from a specific file.

  - by John

  I have fileA.php on SERVER_A and fileB.php on SERVER_B fileB.php makes a curl request to fileA.php for it's contents How can fileA.php determine that the request is coming specifically from fileB.php? -- I was thinking about sending the $_SERVER['SCRIPT_NAME'] in fileB.php to fileA.php but since someone can go into fileB.php or any file in general and just do $_SERVER['SCRIPT_NAME'] = 'fileB.php'; it's not really that secure. So how can I determine, for security reasons, that the request is coming from a specific file on a different server?

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• Roundup of HTML 5 vulgarizations and ressources

  - by ximus

  Hi everyone, HTML 5 is going to change the game not just for developers but will also come into the lives of professionals of all trades have an online presence, and web amateurs. These people are not web professionals but HTML and Flash have both been an important part of their general culture of the web. Vulgarization: to make (a technical or abstruse work) easier to understand and more widely known; popularize. (credits to reference.com) What links do you know of vulgarizations of HTML 5 that can help friends, family and colleagues better understand these up and coming changes of the web. Resources on all HTML5 subjects welcome; Fonts, animation, audio, video, offline capabilities, ... Here is a good start: Scribd presentation on their adoption of HTML 5

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• Eliminating false dependencies

  - by Klaus

  Hi all, I have a quite general question regarding false dependencies. As the name implies, those or no real dependencies and can be elimianated. I am aware of techniqes called register renaming that eliminate such dependencies at a hardware level. Of course I could eliminate those already at a "higher" level when writing assembler code that avoids false dependencies. But now I am wondering if also the compiler provides support to keep the number of false dependencies low or does it more rely on the hardware to eliminate those? Thanks

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• How do you compose DataTemplates / link to a child datatemplate in WPF?

  - by Gishu

  Here's the problem. Given a large/intricate datatemplate A, which has 3 sections - General, Properties, Misc. Imagine 3 grids for each. Now I need to reuse the Properties section of the above Datatemplate in another place. Reasons: To avoid redundancy + ensure that further updates to the datatemplate are applied identically to all usages. So I guess what I am asking for is an ability to slot in a link to a child DataTemplate in a parent Datatemplate. What's the best way to go about this ? I found one way to do this.. but I'm not sure if its the right way or the best.. Posting it as an answer below so that it can be rated.

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• PHP no wait sem_acquire?

  - by SerEnder

  Not a specific code question, but more of a general coding question. I'm trying to use a semaphore in a work project to limit the number of users that can access certain processes at a concurrent time. From my understanding the following: $iKey = ftock($sSomeFileLocation,'sOneCharacterString'); //Generate the key if($sem_id = sem_get($iKey){ //1 user allowed if(sem_acquire($sem_id)){ //Do the limited process here sem_release($sem_id); } } The problem that I see here is that if there is already one user who has the semaphore key, then the next user just waits until the first user is done rather than just faulting out. Anyone know of a way that if the max_acquire number has been reached, sem_acquire (or similar) will just return false? Thanks

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• Jquery Validation Central Message Many Errors

  - by Iamjon

  Hi everyone, I have a form that is being valdated with the Jquery Validation Plugin. I have managed to get a centeral message "Please Recheck the form", and to have the input focus on the first error. To get this, I had to override the default message of each of the errors. I was wondering if anyone could help me figure out how I can have it display the error message associated with the first error input instead of a general error message. Here is the code: $("#Help-A-Noobie-Form" ).validate({ invalidHandler: function(form, validator) { $(this).find(":input.error:first").focus(); var message = 'Please Recheck The Form' ; $("#Help-A-Noobie-Form #Message p").addClass('red').html(message); }, showErrors: function(errorMap, errorList) { this.defaultShowErrors(); }, rules: { required:true, email: {email:true}, phone: {digits:true} }, messages: { email: "", phone: "", lastname: "", firstname: "", required:"" } })

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• Linq to SQL and Realtime Data

  - by Jeremy

  I have an application that needs to constantly (every 50ms), call to an MVC action, and pickup/drop off data. I am using Linq to SQL and MVC because of how simple they are to implement, and I know that they aren't perfect when it comes to performance, but it works relatively well, but the best speed I can get with my current approach is 200ms (without requests overlapping). Each call to the site will create a new instance of the datacontext, query/insert it and return that data. Is there a way to have the datacontext static, but submitchanges say every 5 seconds, so that i am pretty much hitting an in-memory version of the data?

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• JSF Pages call ManagedBeans that are not defined on the page and call all getters sometimes more tha

  - by Bill Leeper

  I have several JSF pages that are initializing and accessing ManagedBeans that are not even used on that page. This is creating a really hairy problem for initialization. I either have to make them all session scope and continually make calls to re-inialize or take the performance hit of having them read large amounts of data from the DB whenever they decide to initialize. Some of the managed beans being accessed are not even defined on the page in question. I have done some optimization based on comments related to multiple calls to getters, but I still have the issue that I have a very specialized (and expensive to initialize) bean that is getting called when I don't want it initialized. Any insight into why/what JSF calls might do something like this. I have a very complex page making use of JSTL, Tomahawk and standard JSF tags. I could include code, but its very complex and sensitive in nature.

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• iPhone CoreData Migration and modifying data

  - by ScottL

  I have an app that has both static data and user entered data in the CoreData store. I understand how to do a lightweight migration to a new database version, but how to I add or modify the static data without affecting the users data? If I have 50 static data entries to add and a couple to modify (ie. spelling mistakes) should they be stored in a different sqlite db and copied over? Also, is it possible to look at the version of the data store so that this copy only happens the first time the app is started up after upgrading? Sorry for the general noob type question, but this is the first time I have ever had to deal with this sort of issue. Thanks, Scott

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• Which is more efficent PHP: array_intersect() OR array_intersect_key()

  - by Jordan Rutty

  Is it more efficient to use the key intersect or the value intersect if both key and value have the same contents for example: Array ( [743] => 743 [744] => 744 [745] => 745 [746] => 746 [747] => 747 [748] => 748 ) Is there any difference in performance in using one or the other with the same values. Similar to the difference of using double or single quotes?

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• how to protect an imported win32 dll into a .net application from memory issues

  - by Eric

  I have a c# application that needs to use a legacy win32 dll. The dll is almost its own app, it has dialogs, operations with hardware, etc. When this dll is imported and used, there are a couple of problems that occur: Dragging a dialog (not a windows system dialog, but one created by the dll) across the managed code app causes the UI to not repaint. Further it generates a system out of memory exception from various ui controls. The performance is incredibly slow. There seems to be no way to unload the dll so the memory never gets cleaned up. When we close our managed app, we get another memory exception. At the moment we import each method call as such: [DllImport("dllname.dll", EntryPoint = "MethodName", SetLastError = true, CharSet = CharSet.Auto, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]

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• very simple delegate musing

  - by Ted

  Sometimes the simplest questions make me love C/C++ and C# more and more. Today sitting on the bus musing aout delegates I remembered reading somwhere you don't need to use the new keyword when instaniating a new delegate. For example: public static void SomeMethod(string message) { ... } ... public delegate void TestDelgate(string message); //Define a delegate ........... //create a new instance ..METHOD 1 TestDelgate t = new TestDelgate(SomeMethod); //OR another way to create a new instance ..METHOD 2 TestDelgate t = SomeMethod; //create a new instance ..METHOD 2 So todays questions are What happens under the hood in method 2. Does the compiler expand method 2 into method 1, hence writing TestDelgate t = SomeMethod; is just a shortcut for TestDelgate t = new TestDelgate(SomeMethod);, or is there another reason for the exsitence of method 2 Do you guys think method 1 or method 2 is better for readability (this is a subjective question, but I'd just like to get a unscientific feel of general opinion of stackoverflow :-))

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• C++ Translation Phase Confusion

  - by blakecl

  Can someone explain why the following doesn't work? int main() // Tried on several recent C++ '03 compilers. { #define FOO L const wchar_t* const foo = FOO"bar"; // Will error out with something like: "identifier 'L' is undefined." #undef FOO } I thought that preprocessing was done in an earlier translation phase than string literal operations and general token translation. Wouldn't the compiler be more or less seeing this: int main() { const wchar_t* const foo = L"bar"; } It would be great if someone could cite an explanation from the standard.

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• Roundup of HTML 5 vulgarizations and resources

  - by ximus

  Hi everyone, HTML 5 is going to change the game not just for developers but will also come into the lives of professionals of all trades have an online presence, and web amateurs. These people are not web professionals but HTML and Flash have both been an important part of their general culture of the web. Vulgarization: to make (a technical or abstruse work) easier to understand and more widely known; popularize. (credits to reference.com) What links do you know of vulgarizations of HTML 5 that can help friends, family and colleagues better understand these up and coming changes of the web. Resources on all HTML5 subjects welcome; Fonts, animation, audio, video, offline capabilities, ... Here is a good start: Scribd presentation on their adoption of HTML 5

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• Indexing XMLType columns

  - by Chris

  Hello, I am working with a XMLType and currently experiencing significant performance issues and would like to incorporate indexing to the column type. Currently I am taking the approach of using the XMLTable() and XQuery functions to create a virtual table. I would like to use this Virtual Table to create a function based index on the table containing the XMLType, but I am receiving this error: Error report: SQL Error: ORA-00907: missing right parenthesis 00907. 00000 - "missing right parenthesis" *Cause: *Action: This is the index.. any assistance would be greatly appreciated. CREATE INDEX indx_medicinalproduct ON d.ProductName XMLTable('for $i at $a in /safetyreport/patient//drug for $j in $i/medicinalproduct return element r { $i/medicinalproduct }' PASSING s.safetyreport COLUMNS ProductName varchar2(70) PATH 'medicinalproduct') d;

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• What's a good way to set up a development environment on OS X for ruby, rails, and git?

  - by Ein2015

  I'm going to start development on a web app using ruby, rails, probably either postgres or mysql, and most likely apache. I'll be using a git repository with the master repo on another server. I've searched through stackoverflow and done some Googling... so here's what I have so far... What are your opinions on what's described on this page?: http://robots.thoughtbot.com/post/159805668/2009-rubyists-guide-to-a-mac-os-x-development What about this one?: http://www.buildingwebapps.com/articles/79197-setting-up-rails-on-leopard-mac I don't need helping finding an editor, there's plenty out there (TextMate, TextWrangler, MacVim), but I do need help to make sure I'm setting things up correctly to code, build, and run the web app from my mac. Here's a specific set of scenarios I could use some help on: Testing various versions of rails and/or ruby. Testing performance, vulnerabilities, monitoring queries, etc. Testing different versions of gems. Working on other projects on this same machine.

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• matrix = *((fxMatrix*)&d3dMatrix); //Evil?

  - by Xilliah

  I've been using matrix = *((fxMatrix*)&d3dMatrix); for quite a while. It worked fine until my screen turned black and received a bucket of frustration on my desk. fxMatrix contains 4 fxVectors. fxVector used to be 16 bytes, but now it was suddenly 20. This was because it inherited fxStreamable, which added the vTable. So one solution is of course just to not inherit fxStreamable, and leave a comment saying that it must always be 16 bytes and never more. Another solution would be to make conversion functions, and copy the matrix completely. This makes it more secure, but has an impact on the performance. I suppose this is the best idea. Another solution is to not convert at all, and stick to D3DXMATRIX, but this makes the engine inconsistent and I personally really dislike this idea. What is your opinion?

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• Collection type generated by for with yield

  - by Jesper

  When I evaluate a for in Scala, I get an immutable IndexedSeq (a collection with array-like performance characteristics, such as efficient random access): scala> val s = for (i <- 0 to 9) yield math.random + i s: scala.collection.immutable.IndexedSeq[Double] = Vector(0.6127056766832756, 1.7137598183155291, ... Does a for with a yield always return an IndexedSeq, or can it also return some other type of collection class (a LinearSeq, for example)? If it can also return something else, then what determines the return type, and how can I influence it? I'm using Scala 2.8.0.RC3.

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• Linq to SQL - design question.

  - by UshaP

  HI, Currently i have one big datacontex with 35 tables (i dragged all my DB tables to the designer). I must admit it is very comfortable cause i have ORM to my full DB and query with linq is easy and simple. My questions are: 1. Would you consider it bad design to have one datacontext with 35 tables or should i split it to logic units? 2. Is there any performance penalties for using such a big datacontext? Thanks, Pini.

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• Deferred printing in Java

  - by Bober02

  I have a specific issue with general console printing and I was wondering whether anyone has a solution for it. I am trying to print a dataTable which would look like sth like this: Table ---------------------- Name |Surname | ---------------------- Mike |Mikhailowish| Rafaello|Mirena | and so on. In order to print the border of the bar I need to know what the maximum length of each column value is. I don't want to go through the whole database to find that out and then again to print it. I would rather like to do sth like: System.out.printLater(s); //herejust leave a pointer to a StringBuilder you will build ... s.append("--------"); ... System.out.printAllDeferred(); I understand the above is probably in 99.99999% chances impossible, but perhaps you guys have a clever way of achieving the above?

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• Why does schema.rb change (in the eyes of Git) when just running rake db:migrate?!

  - by erskingardner

  This is a little general I know, but it's been bugging the hell out of me. I've been working on lots of rails projects remotely with Git and every time I do a git pull and see that there is some sort of data change (migration, or schema.rb change) I do a rake db:migrate. These generally run fine and I can continue working. But if you do a git pull and then git status, your working directory is clean (obviously) then do a rake db:migrate (obviously when there are changes) and another git status and all the sudden your db/schema.rb has changed. I have been just doing a git checkout immediately to reset back to the latest committed version of the schema.rb file, but why should this be necessary?! What is rails doing? Updating a timestamp? I can't seem to figure out what the diff is but maybe I'm just missing something?

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• PCI function number for SATA AHCI controller

  - by Look Alterno

  I'm debugging a second stage boot loader for a PC with SATA AHCI controller. I'm able to enumerate the PCI bus and find the hard disk. So far, so good. Now, lspci in my notebook (Dell Inspiron 1525) show me: -[0000:00]-+-1f.0 Intel Corporation 82801HEM (ICH8M) LPC Interface Controller +-1f.1 Intel Corporation 82801HBM/HEM (ICH8M/ICH8M-E) IDE Controller +-1f.2 Intel Corporation 82801HBM/HEM (ICH8M/ICH8M-E) SATA AHCI Controller \-1f.3 Intel Corporation 82801H (ICH8 Family) SMBus Controller My question: Is SATA AHCI Controller always function 2 in any PC? If not, how I found? I don't pretend to be general; booting my notebook will be good enough, without compromise further refinements.

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• Exception and Inheritance in JAVA

  - by user1759950

  Suppose we have this problem public class Father{ public void method1(){...} } public class Child1 extends Father{ public void method1() throws Exception{ super.method1(); ... } } Child1 extends Father and override method1 but given implementation Child1.method1 now throws a exception, this wont compile as override method can't throw new exceptions. What is the best solution? Propagate the required exception to the Father.. to me this is against encapsulation, inheritance and general OOP ( the father potentially throw and exception that will never happen ) Use a RuntimeException instead? This solution wont propagate the Exception to the father but I read In Oracle docs and others sources states class of exceptions should be used when "Client code cannot do anything" this is not that case, this exception will b useful to recover blablabla ( why is wrong to use RuntimeException instead? ) Other.. thanks, Federico

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