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• Where can I find BLAS example code (in Fortran)?

  - by Feynman

  I have been searching for decent documentation on blas, and I have found some 315 pages of dense material that ctrl-f does not work on. It provides all the information regarding what input arguments the routines take, but there are a LOT of input arguments and I could really use some example code. I am unable to locate any. I know there has to be some or no one would be able to use these libraries! Specifically, I use ATLAS installed via macports on a mac osx 10.5.8 and I use gfortran from gcc 4.4 (also installed via macports). I am coding in Fortran 90. I am still quite new to Fortran, but I have a fair amount of experience with mathematica, matlab, perl, and shell scripting. I would like to be able to initialize and multiply a dense complex vector by a dense symmetric (but not hermitian) complex matrix. The elements of the matrix are defined through a mathematical function of the indices--call it f(i,j). Could anyone provide some code or a link to some code?

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• Extract history from Korn shell

  - by Luc

  I am not happy about the history file in binary format of the Korn shell. I like to "collect" some of my command lines, many of them actually, and for a long time. I'm talking about years. That doesn't seem easy in Korn because the history file is not plain text so I can't edit it, and a lot of junk is piling up in it. By "junk" I mean lines that I don'twant to keep, like 'cat' or 'man'. So I added these lines to my .profile: fc -ln 1 9999 ~/khistory.txt source ~/loghistory.sh ~/khistory.txt loghistory.sh contains a handful of sed and sort commands that gets rid of a lot of the junk. But apparently it is forbidden to run fc in the .profile file. I can't login whenever I do, the shell exits right away with signal 11. So I removed that 'fc -l' line from my .profile file and added it to the loghistory.sh script, but the shell still crashes. I also tried this line in my .profile: strings ~/.sh_history ~/khistory.txt source ~/loghistory.sh That doesn't crash, but the output is printed with an additional, random character in the beginning of many lines. I can run 'fc -l' on the command line, but that's no good. I need to automate that. But how? How can I extract my ksh history as plain text? TIA

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• Using callback functions for error handling in C

  - by Earlz

  Hi, I have been thinking about the difficulty incurred with C error handling.. like who actually does if(printf("hello world")==-1){exit(1);} But you break common standards by not doing such verbose, and usually useless coding. Well what if you had a wrapper around the libc? like so you could do something like.. //main... error_catchall(my_errors); printf("hello world"); //this will automatically call my_errors on an error of printf ignore=1; //this makes it so the function will return like normal and we can check error values ourself if(fopen.... //we want to know if the file opened or not and handle it ourself. } int my_errors(){ if(ignore==0){ _exit(1); //exit if we aren't handling this error by flagging ignore } return 0; //this is called when there is an error anywhere in the libc } ... I am considering making such a wrapper as I am synthesizing my own BSD licensed libc(so I already have to touch the untouchable..), but I would like to know what people think about it.. would this actually work in real life and be more useful than returning -1?

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• php: autoload exception handling.

  - by YuriKolovsky

  Hello again, I'm extending my previous question (Handling exceptions within exception handle) to address my bad coding practice. I'm trying to delegate autoload errors to a exception handler. <?php function __autoload($class_name) { $file = $class_name.'.php'; try { if (file_exists($file)) { include $file; }else{ throw new loadException("File $file is missing"); } if(!class_exists($class_name,false)){ throw new loadException("Class $class_name missing in $file"); } }catch(loadException $e){ header("HTTP/1.0 500 Internal Server Error"); $e->loadErrorPage('500'); exit; } return true; } class loadException extends Exception { public function __toString() { return get_class($this) . " in {$this->file}({$this->line})".PHP_EOL ."'{$this->message}'".PHP_EOL . "{$this->getTraceAsString()}"; } public function loadErrorPage($code){ try { $page = new pageClass(); echo $page->showPage($code); }catch(Exception $e){ echo 'fatal error: ', $code; } } } $test = new testClass(); ?> the above script is supposed to load a 404 page if the testClass.php file is missing, and it works fine, UNLESS the pageClass.php file is missing as well, in which case I see a "Fatal error: Class 'pageClass' not found in D:\xampp\htdocs\Test\PHP\errorhandle\index.php on line 29" instead of the "fatal error: 500" message I do not want to add a try/catch block to each and every class autoload (object creation), so i tried this. What is the proper way of handling this?

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• How can someone with no experience learn how to program?

  - by Mugatu

  A friend and I have been coming up with website ideas for a couple years, mostly just jotting them down whenever we come up with a good, useful idea when browsing the web. For the past 6 months we've hired a couple different programmers to make a couple of the sites for us, but have been disappointed with how it's gone. Been too slow and too many miscommunications for our liking. So like the saying goes if you want something done right do it yourself, we're going to do it ourselves. I know nothing about programming, I've never written a line of code in my life. I consider myself very good with math and about as logical as you can get, but I have zero real-life programming knowledge. The sites we want to make are all pretty 'Web 2.0'ish', meaning user-generated content, commenting on posts, pages that change on the fly, etc. So here are some of my questions for anyone who's been there before: Is there a language you'd recommend learning first? Something that is a good indicator how most other languages work? What web programming languages do you recommend learning first based on popularity both now and the future. I don't want to learn a language that's going to be outdated by the time I'm an expert at it. Any specific books you'd recommend? Any general advice you'd give to someone literally starting at square zero for coding who plans on being in it for the long haul?

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• How to make use of Grails Dependencies in your IDE

  - by raoulsson

  Hi All, So I finally got my dependencies working with Grails. Now, how can my IDE, eg IntelliJ or Eclipse, take advantage of it? Or do I really have to manually manage what classes my IDE knows about at "development time"? If the BuildConfig.groovy script is setup right (see here), you will be able to code away with vi or your favorite editor without any troubles, then run grails compile which will resolve and download the dependencies into the Ivy cache and off you go... If, however, you are using an IDE like Eclipse or IntelliJ, you will need the dependencies at hand while coding. Obviously - as these animals will need them for the "real time" error detection/compilation process. Now, while it is certainly possible to code with all the classes shining up in bright red all over the place that are unknown to your IDE, it is certainly not much fun... The Maven support or whatever it is officially called lives happily with the pom file, no extra "jar directory" pointers needed, at least in IntelliJ. I would like to be able to do the same with Grails dependencies. Currently I am defining them in the BuildConfig.groovy and additionally I copy/paste the current jars around on my local disk and let the IDE point to it. Not very satisfactory, as I am working in a highly volatile project module environment with respect to code change. And this situation ports me directly into "jar hell", as my "develop- and build-dependencies" easily get out of sync and I have to manage manually, that is, with my brain... And my brain should be busy with other stuff... Thanks! Raoul P.S: I'm currently using Grails 1.2M4 and IntelliJ 92.105. But feel free to add answers on future versions of Grails and different, future IDEs, as the come in...

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• Python: Errors saving and loading objects with pickle module

  - by Peterstone

  Hi, I am trying to load and save objects with this piece of code I get it from a question I asked a week ago: Python: saving and loading objects and using pickle. The piece of code is this: class Fruits: pass banana = Fruits() banana.color = 'yellow' banana.value = 30 import pickle filehandler = open("Fruits.obj","wb") pickle.dump(banana,filehandler) filehandler.close() file = open("Fruits.obj",'rb') object_file = pickle.load(file) file.close() print(object_file.color, object_file.value, sep=', ') At a first glance the piece of code works well, getting load and see the 'color' and 'value' of the saved object. But, what I pursuit is to close a session, open a new one and load what I save in a past session. I close the session after putting the line filehandler.close() and I open a new one and I put the rest of your code, then after putting object_file = pickle.load(file) I get this error: Traceback (most recent call last): File "<pyshell#5>", line 1, in <module> object_file = pickle.load(file) File "C:\Python31\lib\pickle.py", line 1365, in load encoding=encoding, errors=errors).load() AttributeError: 'module' object has no attribute 'Fruits' Can anyone explain me what this error message means and telling me how to solve this problem? Thank so much and happy new year!!

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• Xlib.h and Xutil.h not found in Eclipse, how can I fix this?

  - by eclipseNoob

  Hi, I'm a newbie to Eclipse IDE for C/C++ development. I just installed MingW and set it up as my system's environment variable. I am trying to make an application that uses the X library but eclipse cant seem to find it. Eclipse works with any other simple standard library functions but it cant find the X library. Please Help! Here's a sample code snippet that's failing: #include <stdio.h> #include <X11/Xlib.h> // Can't find this #include <X11/Xutil.h> // Or this... int main() { printf("Hello"); return 0; } Do I have to download the X library from somewhere? If so then from where and where do I paste it to? Please tell me what to do in order for me to start coding using the Xlib in Eclipse. If you find any useful links, please dont hesitate to post. Thanks.

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• Can not open ports in iptables on CentOS 5??

  - by abszero

  I am trying to open up ports in CentOS's firewall and am having a terrible go at it. I have followed the "HowTo" here: http://wiki.centos.org/HowTos/Network/IPTables as well as a few other places on the Net but I still can't get the bloody thing to work. Basically I wanted to get two things working: VNC and Apache over the internal network. The problem is that the firewall is blocking all attempts to connect to these services. Now if I issue service iptables stop and then try to access the server via VNC or hit the webserver everything works as expected. However the moment I turn iptables back on all of my access is blocked. Below is a truncated version of my iptables file as it appears in vi -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 5801 -j ACCEPT -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 5901 -j ACCEPT -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 6001 -j ACCEPT -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 5900 -j ACCEPT -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT Really I would just be happy if I could get port 80 opened up for Apache since I can do most stuff via putty but if I could figure out VNC as well that would be cool. As far as VNC goes there is just a single/user desktop that I am trying to connect to via: [ipaddress]:1 Any help would be greatly appreciated!

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• Objective C code to handle large amount of data processing in iPhone

  - by user167662

  I had the following code that takes in 14 mb or more of image data encoded in base4 string and converts them to jpeg before writing to a file in iphone. It crashes my program giving the following error : Program received signal: “0”. warning: check_safe_call: could not restore current frame I tweak my program and it can process a few more images before the error appear again. My coding is as follows: // parameters is an array where the fourth element contains a list of images in base64 >encoded string NSMutableArray *imageStrList = (NSMutableArray*) [parameters objectAtIndex:5]; while (imageStrList.count != 0) { NSString *imgString = [imageStrList objectAtIndex:0]; // Create a file name using my own Utility class NSString *fileName = [Utility generateFileNName]; NSData *restoredImg = [NSData decodeWebSafeBase64ForString:imgString]; UIImage *img = [UIImage imageWithData: restoredImg]; NSData *imgJPEG = UIImageJPEGRepresentation(img, 0.4f); [imgJPEG writeToFile:fileName atomically:YES]; [imageStrList removeObjectAtIndex:0]; } I tried playing around with UIImageJPEGRepresentation and found out that the lower the value, the more image it can processed but this should not be the way. I am wondering if there is anyway to free up memory of the imageStrList immediately after processing each image so that it can be used by the next one in the line.

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• Trouble with building up a string in Clojure

  - by Aki Iskandar

  Hi gang - [this may seem like my problem is with Compojure, but it isn't - it's with Clojure] I've been pulling my hair out on this seemingly simple issue - but am getting nowhere. I am playing with Compojure (a light web framework for Clojure) and I would just like to generate a web page showing showing my list of todos that are in a PostgreSQL database. The code snippets are below (left out the database connection, query, etc - but that part isn't needed because specific issue is that the resulting HTML shows nothing between the <body> and </body> tags). As a test, I tried hard-coding the string in the call to main-layout, like this: (html (main-layout "Aki's Todos" "Haircut<br>Study Clojure<br>Answer a question on Stackoverfolw")) - and it works fine. So the real issue is that I do not believe I know how to build up a string in Clojure. Not the idiomatic way, and not by calling out to Java's StringBuilder either - as I have attempted to do in the code below. A virtual beer, and a big upvote to whoever can solve it! Many thanks! ============================================================= ;The master template (a very simple POC for now, but can expand on it later) (defn main-layout "This is one of the html layouts for the pages assets - just like a master page" [title body] (html [:html [:head [:title title] (include-js "todos.js") (include-css "todos.css")] [:body body]])) (defn show-all-todos "This function will generate the todos HTML table and call the layout function" [] (let [rs (select-all-todos) sbHTML (new StringBuilder)] (for [rec rs] (.append sbHTML (str rec "<br><br>"))) (html (main-layout "Aki's Todos" (.toString sbHTML))))) ============================================================= Again, the result is a web page but with nothing between the body tags. If I replace the code in the for loop with println statements, and direct the code to the repl - forgetting about the web page stuff (ie. the call to main-layout), the resultset gets printed - BUT - the issue is with building up the string. Thanks again. ~Aki

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• A feeling that I'm not that good developer

  - by Karim

  Hi, Im having a strange feeling, but let me first introduce myself as a software developer. I started to program when I was still a kid, I had about 10 or 11 years. I really enjoy my work and never get bored from it. It's amazing how somebody could be paid for what he really likes to do and would be doing it anyway even for free. WHen I first started to program, I was feeling proud of what I was doing, each application I built was for me a success and after 2-3 year I had a feeling that I'm a coding guru. It was a nice feeling ;-) But the more I was in the field, the more types of software I started to develop I was starting to have a feeling that I'm completely wrong in that I'm guru. I felt that I'm not even a mediocre developer. Each new field I start to work on is giving me this feeling. Like when I once developed a device driver for a client, I saw how much I need to learn about device drivers. When I developed a video filter for an application, I saw how much do I still need to learn about DirectShow, Color Spaces, and all the theory behind that. The worst thing was when I started to learn algorithms. It was several years ago. I knew then the basic structures and algorithms like the sorting, some types of trees, some hashtables, strings etc.. and when I really wanted to learn a group of structures I learned about 5-6 new types and saw that in fact even this small group has several hundred subtypes of structures. It's depressing how little time people have in their lives to learn all this stuff. I'm now a software developer with about 10 years of experience and I still feel that I'm not a proficient developer when I think about things that others do in the industry. Is this normal what I'm experiencing or is it a sign of a destructive excessive ambition? Thanks in advance for any comments.

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• How to reference an embedded JCA resource adapater

  - by cg

  For our current J2EE project based on JBoss, we need to interface with a remote system using message driven beans and a JCA resource adapter provided as a RAR file by a third party. I would like to package and deploy the entire project as an EAR file to our JBoss server. Most notably, the RAR file should be embedded within the EAR file and not be deployed globally. All of this is working fine so far, but I'm not particularly happy with the way the RAR file is referenced. The jboss.xml packaged with the MDB for example, currently looks like this: <jboss> <enterprise-beans> <message-driven> <ejb-name>testBean1</ejb-name> <resource-adapter-name>test1.ear#thirdparty-1.0.rar</resource-adapter-name> </message-driven> </enterprise-beans> </jboss> While this is generally working fine, it will break when the EAR file is renamed to "test2.ear". Is there a way to reference the embedded RAR file without hard-coding the containing archive's name?

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• How to maintain long-lived python projects w.r.t. dependencies and python versions ?

  - by Gyom

  short version: how can I get rid of the multiple-versions-of-python nightmare ? long version: over the years, I've used several versions of python, and what is worse, several extensions to python (e.g. pygame, pylab, wxPython...). Each time it was on a different setup, with different OSes, sometimes different architectures (like my old PowerPC mac). Nowadays I'm using a mac (OSX 10.6 on x86-64) and it's a dependency nightmare each time I want to revive script older than a few months. Python itself already comes in three different flavours in /usr/bin (2.5, 2.6, 3.1), but I had to install 2.4 from macports for pygame, something else (cannot remember what) forced me to install all three others from macports as well, so at the end of the day I'm the happy owner of seven (!) instances of python on my system. But that's not the problem, the problem is, none of them has the right (i.e. same set of) libraries installed, some of them are 32bits, some 64bits, and now I'm pretty much lost. For example right now I'm trying to run a three-year-old script (not written by me) which used to use matplotlib/numpy to draw a real-time plot within a rectangle of a wxwidgets window. But I'm failing miserably: py26-wxpython from macports won't install, stock python has wxwidgets included but also has some conflict between 32 bits and 64 bits, and it doesn't have numpy... what a mess ! Obviously, I'm doing things the wrong way. How do you usally cope with all that chaos ?

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• java : how to handle the design when template methods throw exception when overrided method not throw

  - by jiafu

  when coding. try to solve the puzzle: how to design the class/methods when InputStreamDigestComputor throw IOException? It seems we can't use this degisn structure due to the template method throw exception but overrided method not throw it. but if change the overrided method to throw it, will cause other subclass both throw it. So can any good suggestion for this case? abstract class DigestComputor{ String compute(DigestAlgorithm algorithm){ MessageDigest instance; try { instance = MessageDigest.getInstance(algorithm.toString()); updateMessageDigest(instance); return hex(instance.digest()); } catch (NoSuchAlgorithmException e) { LOG.error(e.getMessage(), e); throw new UnsupportedOperationException(e.getMessage(), e); } } abstract void updateMessageDigest(MessageDigest instance); } class ByteBufferDigestComputor extends DigestComputor{ private final ByteBuffer byteBuffer; public ByteBufferDigestComputor(ByteBuffer byteBuffer) { super(); this.byteBuffer = byteBuffer; } @Override void updateMessageDigest(MessageDigest instance) { instance.update(byteBuffer); } } class InputStreamDigestComputor extends DigestComputor{ // this place has error. due to exception. if I change the overrided method to throw it. evey caller will handle the exception. but @Override void updateMessageDigest(MessageDigest instance) { throw new IOException(); } }

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• Moving from NHibernate to FluentNHibernate: assembly error (related to versions)?

  - by goober

  Not sure where to start, but I had gotten the most recent version of NHibernate, successfully mapped the most simple of business objects, etc. When trying to move to FluentNHibernate and do the same thing, I got this error message on build: "System.IO.FileLoadException: Could not load file or assembly 'NHibernate, Version=2.1.0.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference." Background: I'm new to Hibernate, NHibernate, and FluentNHibernate -- but not to .NET, C#, etc. Database I have a database table called Category: (PK) CategoryID (type: int), unique, auto-incrementing UserID (type: uniqueidentifier) -- given the value of the user Guid in ASP.NET database Title (type: varchar(50) -- the title of the category Components involved: I have a SessionProviderClass which creates the mapping to the database I have a Category class which has all the virtual methods for FluentNHibernate to override I have a CategoryMap : ClassMap class, which does the fluent mappings for the entity I have a CategoryRepository class that contains the method to add & save the category I have the TestCatAdd.aspx file which uses the CategoryRepository class. Would be happy to post code for any of those, but I'm not sure that it's necessary, as I think the issue is that somewhere there's a version conflict between what FluentNHibernate references and the NHibernate I have installed from before. Thanks in advance for any help you can give!

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• how to make a software and preserve database integrity and correctness and please help confused

  - by user287745

  i have made an application project in vs 08 c#, sql server from vs 08. the database has like 20 tables and many fields in each have made an interface for adding deleting editting and retrieving data according to predefined needs of the users. now i have to 1) make to project in to a software which i can deliver to professor. that is he can just double click the icon and the software simply starts. no vs 08 needed to start the debugging 2) the database will be on one powerful computer (dual core latest everything win xp) and the user will access it from another computer connected using LAN i am able to change the connection string to the shared database using vs 08/ debugger whenever the server changes but how am i supposed to do that when its a software? 3)there will by many clients am i supposed to give the same software to every one, so they all can connect to the database, how will the integrity and correctness of the database be maintained? i mean the db.mdf file will be in a folder which will be shared with read and write access. so its not necessary that only one user will write at a time. so is there any coding for this or? please help me out here i am stuck do not know what to do i have no practical experience, would appreciate all the help thank you

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• Building static (but complicated) lookup table using templates.

  - by MarkD

  I am currently in the process of optimizing a numerical analysis code. Within the code, there is a 200x150 element lookup table (currently a static std::vector < std::vector < double ) that is constructed at the beginning of every run. The construction of the lookup table is actually quite complex- the values in the lookup table are constructed using an iterative secant method on a complicated set of equations. Currently, for a simulation, the construction of the lookup table is 20% of the run time (run times are on the order of 25 second, lookup table construction takes 5 seconds). While 5-seconds might not seem to be a lot, when running our MC simulations, where we are running 50k+ simulations, it suddenly becomes a big chunk of time. Along with some other ideas, one thing that has been floated- can we construct this lookup table using templates at compile time? The table itself never changes. Hard-coding a large array isn't a maintainable solution (the equations that go into generating the table are constantly being tweaked), but it seems that if the table can be generated at compile time, it would give us the best of both worlds (easily maintainable, no overhead during runtime). So, I propose the following (much simplified) scenario. Lets say you wanted to generate a static array (use whatever container suits you best- 2D c array, vector of vectors, etc..) at compile time. You have a function defined- double f(int row, int col); where the return value is the entry in the table, row is the lookup table row, and col is the lookup table column. Is it possible to generate this static array at compile time using templates, and how?

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• Parsing XHTML with inline tags

  - by user290796

  Hi, I'm trying to parse an XHTML document using TBXML on the iPhone (although I would be happy to use either libxml2 or NSXMLParser if it would be easier). I need to extract the content of the body as a series of paragraphs and maintain the inline tags, for example: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"> <head> <title>Title</title> <link rel="stylesheet" href="css/style.css" type="text/css"/> <meta http-equiv="Content-Type" content="application/xhtml+xml; charset=utf-8"/> </head> <body> <div class="body"> <div> <h3>Title</h3> <p>Paragraph with <em>inline</em> tags</p> <img src="image.png" /> </div> </div> </body> </html> I need to extract the paragraph but maintain the <em>inline</em> content with the paragraph, all my testing so far has extracted that as a subelement without me knowing exactly where it fitted in the paragraph. Can anyone suggest a way to do this? Thanks.

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• Passing Extras and screen rotation

  - by Luis A. Florit

  This kind of questions appear periodically. Sorry if this has been covered before, but I'm a newbie and couldn't find the appropriate answer. It deals with the correct implementation of communication between classes and activities. I made a gallery app. It has 3 main activities: the Main one, to search for filenames using a pattern; a Thumb one, that shows all the images that matched the pattern as thumbnails in a gridview, and a Photo activity, that opens a full sized image when you click a thumb in Thumbs. I pass to the Photo activity via an Intent the filenames (an array), and the position (an int) of the clicked thumb in the gridview. This third Photo activity has only one view on it: a TouchImageView, that I adapted for previous/next switching and zooming according to where you shortclick on the image (left, right or middle). Moreover, I added a longclick listener to Photo to show EXIF info. The thing is working, but I am not happy with the implementation... Some things are not right. One of the problems I am experiencing is that, if I click on the right of the image to see the next in the Photo activity, it switches fine (position++), but when rotating the device the original one at position appears. What is happening is that Photo is destroyed when rotating the image, and for some reason it restarts again, without obeying super.onCreate(savedInstanceState), loading again the Extras (the position only changed in Photo, not on the parent activities). I tried with startActivityForResult instead of startActivity, but failed... Of course I can do something contrived to save the position data, but there should be something "conceptual" that I am not understanding about how activities work, and I want to do this right. Can someone please explain me what I am doing wrong, which is the best method to implement what I want, and why? Thanks a lot!!!

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• EF/LINQ: Where() against a property of a subtype

  - by ladenedge

  I have a set of POCOs, all of which implement the following simple interface: interface IIdObject { int Id { get; set; } } A subset of these POCOs implement this additional interface: interface IDeletableObject : IIdObject { bool IsDeleted { get; set; } } I have a repository hierarchy that looks something like this: IRepository<T <: BasicRepository<T <: ValidatingRepository<T (where T is IIdObject) I'm trying to add a FilteringRepository to the hierarchy such that all of the POCOs that implement IDeletableObject have a Where(p => p.IsDeleted == false) filter applied before any other queries take place. My goal is to avoid duplicating the hierarchy solely for IDeletableObjects. My first attempt looked like this: public override IQueryable<T> Query() { return base.Query().Where(t => ((IDeletableObject)t).IsDeleted == false); } This works well with LINQ to Objects, but when I switch to an EF backend I get: "LINQ to Entities only supports casting Entity Data Model primitive types." I went on to try some fancier parameterized solutions, but they ultimately failed because I couldn't make T covariant in the following case for some reason I don't quite understand: interface IQueryFilter<out T> // error { Expression<Func<T, bool>> GetFilter(); } I'd be happy to go into more detail on my more complicated solutions if it would help, but I think I'll stop here for now in hope that someone might have an idea for me to try. Thanks very much in advance!

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• In which domains are message oriented middleware like AMQP useful?

  - by cocotwo

  What problem do MOM (Message Oriented Middleware) solve? Scalability? Integration? In which domain are they typically used and in which domains are they typically not used? For example, say, is Google using such solution for it's main search engine or to power GMail? What about big websites like Walmart, eBay, FedEx (pretty much a Java shop) and buy.com (pretty much an MS shop)? Does MOM solve a need there? Does it make any sense when you're writing a Webapp where you control the server-side and have an homogenous environment (say tens of Amazon EC2 instances all running Linux + Java JVMs) there and where the clients are, well, Web browsers? Does it make sense for desktop apps that need to communicate with a server? Or is it 'only' for big enterprise stuff where you typically have a happy mix of countless of different systems that needs to communicate in a way or another? I'm a bit confused as to what they're useful for and I think that with example of where they're appropriate and where they're not appropriate I could better understand their use.

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• Controlling the alpha of a UIImageView with Slider ..Can' t get it

  - by user1824839

  first i' d like to say this Forum was really helpfull for me that just started coding some weeks ago .. I succeed to do a quite nice app for the moment , than, but i m stuck on this : HOW COULD I CONTROL THE ALPHA OF A UIIMAGEVIEW , WITH A SLIDER EMBEDED IN ANOTHER VIEW ??? ; Basically i' like to do like the alpha slider of this : http://www.edumobile.org/iphone/how-to-make-an-app-2/controlling-a-uiviews-properties-for-ipad/ , but for a UIImageView. I promised i searched for hours , and didnt find how to do it ... Could someone have some minutes to give me ideas ?? Sorry for my poor english too. Thanks if you can. L. The resume of the link i posted, only focussing on the alpha property would be : ( considering a UIView ( View ) embeded in a ViewController ( ViewController ): enter code here ----View.h----- @interface View : UIView @property ( nonatomic, assign ) CGFloat alpha; @end enter code here ----View.m---- @implementation View @synthesize alpha; ?} @end enter code here ------ViewController.h----- import "View.h" @interface ViewController : UIViewController @property (nonatomic, strong) IBOutlet View *view; ?- (IBAction)alphaChanged:(UISlider *)sender; @end enter code here -------ViewController.m------ @interface ViewController () @end @implementation ViewController @synthesize view; (View *)view {?     if (!view) {?        view = [[View alloc] init];?    }?    return view;?} enter code here (IBAction)redChanged:(UISlider *)sender? {?    self.circle.alpha = sender.value;?    [self.circle setNeedsDisplay];?} (void)viewDidLoad ?{?    [super viewDidLoad];?         ?    self.circle.alpha = (CGFloat)1;?} (void)didReceiveMemoryWarning? {?  [super didReceiveMemoryWarning];?    @end enter code here

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• Effective books for learning the intricacies of business application development?

  - by OffApps Cory

  I am a self taught "developer". I use the term loosely because I only know enough to make myself dangerous. I have no theory background, and I only pick up things to get this little tool to work or make that control do what I want. That said, I am looking for some reading material that explains some of the theory behind application development especially from a business standpoint. Really I need to understand what all of these terms that float around really talk about. Business Logic Layer, UI abstraction level and all that. Anyone got a reading list that they feel helped them understand this stuff? I know how to code stuff up so that it works. It is not pretty mostly because I don't know the elegant way of doing it, and it is not planned out very well (I also don't know how to plan an application). Any help would be appreciated. I have read a number of books on what I thought was the subject, but they all seem to rehash basic coding and what-not. This doesn't have to be specific to VB.NET or WPF (or Entity Framework) but anything with those items would be quite helpful.

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• Why does mobile first responsive design tend to not use max-width queries alongside the min-width queries?

  - by Sam

  First off, I understand the basic principles behind mobile first responsive web design, and totally agree with them. But one thing I don't understand: In my experience, not all styles for small screens can be used for the larger version of a website. For example, usually smaller versions tend to have larger clickable areas, hamburger navigation, etc. So I sometimes have to override these specific styles, aside from just progressively enhancing the base styles. So I was wondering: why is max-width rarely mentioned (or used) in the context of mobile-first responsive web design? Because it looks like it could be used to isolate styles for smaller screens that are not useful for larger screens, and would thus prevent unnecessary duplication of code. A quote which mentions min-width as typically mobile-first, but not max-width: Mobile first, from a coding perspective, means that your base style is typically a single-column, fully-fluid layout. You use @media (min-width: whatever) to add a grid-based layout on top of that. from: http://gomakethings.com/mobile-first-and-internet-explorer/ EDIT: So to be more specific: I was wondering if there is a reason to exclude max-width from a mobile-first responsive design (as it seems like it can be useful for writing your css as DRY as possible, as some styles for small screens will not be used for bigger screens).

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