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  • Erlang ODBC parameter query with null parameters

    - by Schlomer
    Is it possible to pass null values to parameter queries? For example Sql = "insert into TableX values (?,?)". Params = [{sql_integer, [Val1]}, {sql_float, [Val2]}]. % Val2 may be a float, or it may be the atom, undefined odbc:param_query(OdbcRef, Sql, Params). Now, of course odbc:param_query/3 is going to complain if Val2 is undefined when trying to match to a sql_float, but my question is... Is it possible to use a parameterized query, such as: Sql = "insert into TableY values (?,?,?,?,?,?,?,?,?)". with any null parameters? I have a use case where I am dumping a large number of real-time data into a database by either inserting or updating. Some of the tables I am updating have a dozen or so nullable fields, and I do not have a guarantee that all of the data will be there. Concatenating a SQL together for each query, checking for null values seems complex, and the wrong way to do it. Having a parameterized query for each permutation is simply not an option. Any thoughts or ideas would be fantastic! Thank you!

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  • Do complex JOINs cause high coupling and maintenance problems ?

    - by ashkan.kh.nazary
    Our project has ~40 tables with complex relations.A colleague believes in using long join queries which enforces me to learn about tables outside of my module but I think I should not concern about tables not directly related to my module and use data access functions (written by those responsible for other modules) when I need data from them. Let me clarify: I am responsible for the ContactVendor module which enables the customers to contact the vendor and start a conversation about some specific product. Products module has it's own complex tables and relations with functions that encapsulate details (for example i18n, activation, product availability etc ...). Now I need to show the product title of some product related to some conversation between the vendor and customers. I may either write a long query that retrieves the product info along with conversation stuff in one shot (which enforces me to learn about Product tables) OR I may pass the relevant product_id to the get_product_info(int) function. First approach is obviously demanding and introduces many bad practices and things I normally consider fault in programming. The problem with the second approach seems to be the countless mini queries these access functions cause and performance loss is a concern when a loop tries to fetch product titles for 100 products using functions that each perform a separate query. So I'm stuck between "don't code to the implementation, code to interface" and performance. What is the right way of doing things ? UPDATE: I'm specially concerned about possible future modifications to those tables outside of my module. What if the Products module decided to change the way they are doing things? or for some reason modify the schema? It means some other modules would break or malfunction until the change is integrated to them. The usual ripple effect problem.

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  • New Rails deployment half working...not sure why?

    - by Meltemi
    I'm in the final stages of going round trip through the entire Rails cycle: development - test - production (on an external server). I'm very close...but seeing some errors with the production version and don't know enough about Rails' "magic" to troubleshoot it yet... all seems well and I can load my app by going to www.mydomain.com/rails and it seems to work...I can interact with my app and create new objects in my database. However, when I go to www.mydomain.com/rails/ (difference is the trailing slash) i get a webpage that just says "Index from public" on it?!? I don't know where that's coming from? index.html is long removed from public. this may or may not be related to why I can't access, say, the first record in one of my classes by calling its controller like so: www.mydomain.com/rails/mycontroller/1 . and yes, there are records in the database. anyway, something's askew. it works fine on development box. but, only half working on production server. anyone know what might be causing this? this app is running on the server box (not development) Installed Passenger on server to serve app via Apache modified my httpd.conf with Passenger's stuff (headache but finally got it to respond) loaded schema into the production database: rake db:schema:load RAILS_ENV=production

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  • Trouble extending event log messages

    - by Matt H
    Hi. I'm trying to add some extended error codes to the event log but I get the following error. The description for Event ID ( 109 ) in Source ( PumpServer ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: The event log file is corrupt.. The message file looks like this and I added the one on the end:- <---snip---> MessageId= SymbolicName=EVMSG_BADREQUEST Language=English The service received an unsupported request. . MessageId= SymbolicName=EVMSG_DEBUG Language=English %1 . MessageId= SymbolicName=EVMSG_STOPPED Language=English The service was stopped. . MessageId= SymbolicName=EVMSG_INVALIDLICENCE Language=English The service does not have a valid licence. Initialization failed. . It compiles fine. The mc program is running over this file and producing a header file of the same name with my new message id showing. // // MessageId: EVMSG_INVALIDLICENCE // // MessageText: // // The service does not have a valid licence. Initialization failed. // #define EVMSG_INVALIDLICENCE 0x0000006DL Any ideas why it's not finding my message? All the others work.

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  • Pulling specific entries from RSS feed [PHP]

    - by n0s
    So, I have an RSS feed with variations of each item. What I want to do is just get entries that contain a specific section of text. For example: <item> <title>RADIO SHOW - CF64K - 05-20-10 + WRAPUP </title> <link>http://linktoradioshow.com</link> <comments>Radio show from 05-20-10</comments> <pubDate>Thu, 20 May 2010 19:12:12 +0200</pubDate> <category domain="http://linktoradioshow.com/browse/199">Audio / Other</category> <dc:creator>n0s</dc:creator> <guid>http://otherlinktoradioshow.com/</guid> <enclosure url="http://linktoradioshow.com/" length="13005" /> </item> <item> <title>RADIO SHOW - CF128K - 05-20-10 + WRAPUP </title> <link>http://linktoradioshow.com</link> <comments>Radio show from 05-20-10</comments> <pubDate>Thu, 20 May 2010 19:12:12 +0200</pubDate> <category domain="http://linktoradioshow.com/browse/199">Audio / Other</category> <dc:creator>n0s</dc:creator> <guid>http://otherlinktoradioshow.com/</guid> <enclosure url="http://linktoradioshow.com/" length="13005" /> </item> I only want to display the results that contain the string CF64K. While it's probably really simple regex, I can't seem to wrap my head around getting it right. I always get seem to only be able to display the string 'CF64K', and not the stuff that surrounds it. Thanks in advance.

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  • NPE annotation scenarios and static-analysis tools for Java

    - by alex2k8
    Here is a number of code snippets that can throw NullPointerException. 01: public void m1(@Nullable String text) { System.out.print(text.toLowerCase()); // <-- expect to be reported. } 02: private boolean _closed = false; public void m1(@Nullable String text) { if(_closed) return; System.out.print(text.toLowerCase()); // <-- expect to be reported. } 03: public void m1(@NotNull String text) { System.out.print(text.toLowerCase()); } public @Nullable String getText() { return "Some text"; } public void m2() { m1(getText()); // <-- expect to be reported. } Different people have access to different static-analysis tools. It would be nice to collect information, what tools are able to detect and report the issues, and what are failing. Also, if you have your own scenarious, please, publish them. Here my results FindBugs (1.3.9): 01: Parameter must be nonnull but is marked as nullable 02: NOT reported 03: NOT reported IntelliJ IDE 9.0.2 (Community edition): 01: Method invocation text.toLowerCase() may produce java.lang.NullPointerException 02: Method invocation text.toLowerCase() may produce java.lang.NullPointerException 03: Argument getText() might be null

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  • Ideas for storing e-mail messages in a Delphi client server application

    - by user193655
    There are many suggestions here and there for storing e-mail messages. Somehow what I am doing is writing an Outlook addin to send emails from inbox/sent folders directly to my application. So only what is really interesting is saved. And I decide where to save it. Imagine this case: I recieve an email from a customer. It's up to me to decide whether I should save it on the customer or on the order 24 that that customer did. So this is why I am doing the add in, and not some automatic storing of emails = noise after some time. This said, how to store the emails? For the emails that I recieve or send through Outlook the idea could be save the whole file in a blob field (so the eml file), may be I can save also other info (like the subject) in another text field. But the problem comes when I write an email from my application. In this case I am not generating an eml file, I send through MAPI data to Outlook to compose an email that I will send with Outlook (so in this case I cannot save the eml), or I directly send it with Indy. Also in this case I don't have the eml file... One idea could be that the all the emails that I auto compose have a special flag that the Add in recognises and therefore when I send the mail it is stored back to the DB. So in this case I can save the eml also of the mails I sent from my application. May you comment?

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  • Case Insensitive Ternary Search Tree

    - by Yan Cheng CHEOK
    I had been using Ternary Search Tree for a while, as the data structure to implement a auto complete drop down combo box. Which means, when user type "fo", the drop down combo box will display foo food football The problem is, my current used of Ternary Search Tree is case sensitive. My implementation is as follow. It had been used by real world for around 1++ yeas. Hence, I consider it as quite reliable. My Ternary Search Tree code However, I am looking for a case insensitive Ternary Search Tree, which means, when I type "fo", the drop down combo box will show me foO Food fooTBall Here are some key interface for TST, where I hope the new case insentive TST may have similar interface too. /** * Stores value in the TernarySearchTree. The value may be retrieved using key. * @param key A string that indexes the object to be stored. * @param value The object to be stored in the tree. */ public void put(String key, E value) { getOrCreateNode(key).data = value; } /** * Retrieve the object indexed by key. * @param key A String index. * @return Object The object retrieved from the TernarySearchTree. */ public E get(String key) { TSTNode<E> node = getNode(key); if(node==null) return null; return node.data; } An example of usage is as follow. TSTSearchEngine is using TernarySearchTree as the core backbone. Example usage of Ternary Search Tree // There is stock named microsoft and MICROChip inside stocks ArrayList. TSTSearchEngine<Stock> engine = TSTSearchEngine<Stock>(stocks); // I wish it would return microsoft and MICROCHIP. Currently, it just return microsoft. List<Stock> results = engine.searchAll("micro");

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  • Android - Basic CRUD (REST/RPC client) to remote server

    - by bsreekanth
    There are lot of discussion about REST client implementation in android, based on the talk at GoogleIO 2010, by Virgil Dobjanschi. My requirement may not necessarily involved, as I have some freedom to choose the configuration. I only target tablets configuration changes can be prevented if no other easy way (fix at Landscape mode etc) I am trying to achieve. Basic CRUD operation to my server (JSON RPC/ REST). Basically mimic an ajax request from android app (no webview, need native app) Based on the above mentioned talk, and some reading I see these options. Implement any of the 3 mentioned in the Google IO talk Especially, the last pattern may be more suitable as I don't care much of caching. But not sure how "real time" is sync implementation. Use HTTP request in AsyncTask. Simplest, but need to avoid re-sending request during change in device configuration (orientation change etc). Even if I fix at one orientation, recreation of activity still happens. So need to handle it elegantly. Use service to handle http request. So far, it say use service for long ruiing request. Not sure whether it is a good approach for simple GET/POST/PUt requests. Please share your experience on what could be the best way.

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  • Loop a formula in excel VBA

    - by CEMG
    I am trying to loop a formula in Column "D" until Column "B" doesn't have any more data. The formula I am adding to Column "D" is : IF(ISNUMBER(C5),C5,IF(C5A5/3+OFFSET(C5,-1,0)) ,IF(C5<C6,((OFFSET(C5,1,0)-OFFSET(C5,-2,0))(A5/3)+OFFSET(C5,-2,0)),""))) So the result I want in Column "D" once the macro is run is this: A B C D 3 May-10 78.0000 78.00000 1 Jun-10 52.06667 2 Jul-10 26.13333 3 Aug-10 0.2000 0.20000 1 Sep-10 0.21393 2 Oct-10 0.22786 3 Nov-10 0.2418 0.24179 1 Dec-10 0.26640 2 Jan-11 0.29102 3 Feb-11 0.3156 0.31563 1 Mar-11 0.34821 2 Apr-11 0.38080 3 May-11 0.4134 0.41338 1 Jun-11 0.44992 2 Jul-11 0.48646 3 Aug-11 0.5230 0.52300 1 Sep-11 0.56440 2 Oct-11 0.60580 3 Nov-11 0.6472 0.64720 1 Dec-11 0.43147 If someone can help me at what I am doing wrong with the VBA codes I would greatly appreciated. My CODES are the following: Sub IsNumeric() // first logic: IF(ISNUMBER(C6),C6 // If Application.IsNumber(Range("c5").Value) Then Range("d5").Value = Range("C5").Value // second logic: IF(C6 ElseIf Range("c6").Value < Range("c5").Value Then Range("d6").Value = Range("c6").Offset(2, 0).Value - Range("c6").Offset(-1, 0).Value * (Range("a6").Value / 3) + Range("c6").Offset(-1, 0).Value // third logic: IF(C6<C7,((OFFSET(C6,1,0)-OFFSET(C6,-2,0))*(A6/3)+OFFSET(C6,-2,0)),""))) // ElseIf Range("c6").Value < Range("c7").Value Then Range("d6").Value = (Range("c6").Offset(1, 0).Select) - Range("c6").Offset(-2, 0).Select * (Range("a6").Select / 3) + Range("c6").Offset(-2, 0).Select Else Range("d6").Value = "" End If End Sub

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  • Ubuntu server or Debian server (to run C++ apps developed on Ubuntu)

    - by skyeagle
    I have written a number of C++ server side daemons for my website, using my Ubuntu 9.10 dev machine. I am now about to venture out to look for a hosting provider etc. This is my problem: I have read on many posts (admittedly old posts) that Debian server is much more robust than Ubuntu server - is this till the case?. In particular, I am constantly "raising elephants" with my Ubuntu 9.10 - this is "ok" for home use, but for a website server, I would not be so forgiving. Also, there seems to be a new "patch" every few weeks - which I would not like on a server (I want to leave the server well alone, and let it get on with its business of serving pages). So in this instance Debian looks a more attractive proposition. I am worried that the C++ apps I have developed on Ubuntu may not be binary compatable with Debian (or I may need to install additional libraries/packages etc to get things to work), and I have zero experience with Debian. Additionally, I dont want to be grappling with the learning curve associated with a new OS, whilst trying to launch a new web site (I am assuming Debian UI is quite different from Ubuntu). In this case, the maxim "the devil you know is better than the one you dont", seems appropriate - and I find Ubuntu a more attractive proposition (atleast I know my apps will run without any probs etc). Can anyone provide some rational advice (based on actual experience), to help me decide which route to take - given the two (conflicting) trains of thought outlined above?

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  • Help with SQL Query

    - by djfrear
    With regards to the following statement: Select * From explorer.booking_record booking_record_ Inner Join explorer.client client_ On booking_record_.labelno = client_.labelno Inner Join explorer.tour_hotel tour_hotel_ On tour_hotel_.tourcode = booking_record_.tourrefcode Inner Join explorer.hotelrecord hotelrecord_ On tour_hotel_.hotelcode = hotelrecord_.hotelref Where booking_record_.bookingdate Not Like '0000-00-00' And booking_record_.tourdeparturedate Not Like '0000-00-00' And hotelrecord_.hotelgroup = "LPL" And Year(booking_record_.tourdeparturedate) Between Year(AddDate(Now(), Interval -5 Year)) And Year(Now()) My MySQL skills are certainly not up to scratch, the actual result set I wish to find is "a customer who has been to 5 or more LPL hotels in the past 5 years". So far I havent got as far as dealing with the count as I'm getting a huge number of results with some 250+ per customer. I assume this is to do with the way I'm joining tables. Schema wise the booking_record table contains a tour reference code, which links to tour_hotel which then contains a hotelcode which links to hotelrecord. This hotelrecord table contains the hotelgroup. The client table is joined to the booking_record via a booking reference and a client may have many bookings. If anyone could suggest a way for me to do this I'd be very grateful and hopefully learn enough to do it myself next time! I've been scratching my head over this one for a few hours now! Customers may have many bookings within booking_record Daniel.

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  • curl not returning content length header

    - by Michael P. Shipley
    Trying to get image file size using curl but content length header is not returned: $url ="http://www.collegefashion.net/wp-content/plugins/feed-comments-number/image.php?1263"; $fp = curl_init(); curl_setopt($fp, CURLOPT_NOBODY, true); curl_setopt($fp, CURLOPT_RETURNTRANSFER, 1); curl_setopt($fp, CURLOPT_FAILONERROR,1); curl_setopt($fp, CURLOPT_REFERER,''); curl_setopt($fp, CURLOPT_URL, $url); curl_setopt($fp, CURLOPT_HEADER,1); curl_setopt($fp, CURLOPT_USERAGENT,'Mozilla/5.0'); $body = curl_exec($fp); var_dump($body): HTTP/1.1 200 OK Date: Sun, 02 May 2010 02:50:20 GMT Server: Apache/2.0.63 (CentOS) X-Powered-By: W3 Total Cache/0.8.5.2 X-Pingback: http://www.collegefashion.net/xmlrpc.php Cache-Control: no-cache, must-revalidate Expires: Sat, 26 Jul 1997 05:00:00 GMT Content-Type: image/png It works via ssh though: curl -i http://www.collegefashion.net/wp-content/plugins/feed-comments-number/image.php?1263 HTTP/1.1 200 OK Date: Sun, 02 May 2010 03:38:43 GMT Server: Apache/2.0.63 (CentOS) X-Powered-By: W3 Total Cache/0.8.5.2 X-Pingback: http://www.collegefashion.net/xmlrpc.php Cache-Control: no-cache, must-revalidate Expires: Sat, 26 Jul 1997 05:00:00 GMT Content-Length: 347 Content-Type: image/png

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  • How do I use price data in one table for a calculation that is stored in another table?

    - by shane
    I'm still leanring PHP/MySQL but have learned quite a bit thanks to codies on StackOverflow. I'm trying to setup a sort of room reservations system using two tables: SETUP: Room price table: Has, prices for a type room a client may want to rent as well as the dates (day of week) they wish to use it. Pricing varies based on day of the week and per room. I've setup a different table for each room type as each room type carries different pricing for each day of the week. So, There is an Alpha room table, Bravo room, etc. Within Alpha table are headers for the days of the week with pricing pre-entered into the rows. Client info table: Has the name, address, date of room use, etc data for the specific client. EXAMPLE: Alpha-room price table: Sun = $100; Mon = $200; Tue=$300 and so on. Bravo-room price table: Sun = $100; Mon = $200; Tue=$300 and so on. Client data table: ClientName; date-of-room-use; address; day_subtotal; grand_total. QUESTION: I'm trying to find PHP code that will: look at the date of room use in the client data table, look up the associated cost for that date in the specific room pricing table, record that unit cost in the day subtotal of the client data table and sum a grand total in the grand total row of the client data table (assuming the room may be used more than one day by the customer). I know there's something to do with join but I'm finding it difficult to grasp the concept and, if someone can demonstrate using this example, I think I will have a better understanding of how to work this sort of transaction. Thank you ALL in advance for your suggestions or alternatvie approaches.

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  • Losing URI segments when paginating with CodeIgniter

    - by Danny Herran
    I have a /payments interface where the user should be able to filter via price range, bank, and other stuff. Those filters are standard select boxes. When I submit the filter form, all the post data goes to another method called payments/search. That method performs the validation, saves the post values into a session flashdata and redirects the user back to /payments passing the flashdata name via URL. So my standard pagination links with no filters are exactly like this: payments/index/20/ payments/index/40/ payments/index/60/ And if you submit the filter form, the returning URL is: payments/index/0/b48c7cbd5489129a337b0a24f830fd93 This works just great. If I change the zero for something else, it paginates just fine. The only issue however is that the << 1 2 3 4 page links wont keep the hash after the pagination offset. CodeIgniter is generating the page links ignoring that additional uri segment. My uri_segment config is already set to 3: $config['uri_segment'] = 3; I cannot set the page offset to 4 because that hash may or may not exists. Any ideas of how can I solve this? Is it mandatory for CI to have the offset as the last segment in the uri? Maybe I am trying an incorrect approach, so I am all ears. Thank you folks.

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  • merging javascript arrays for json

    - by Nat
    I serially collect information from forms into arrays like so: list = {"name" : "John", "email" : "[email protected]", "country" : "Canada", "color" : "blue"}; identifier = "first_round"; list = {"name" : "Harry", "email" : "[email protected]", "country" : "Germany"}; identifier = "second_round"; I want to combine them into something (I may have braces where I need brackets) like: list_all = { "first_round" : {"name" : "John", "email" : "[email protected]", "country" : "Canada", "color" : "blue"} , "second_round" : {"name" : "Harry", "email" : "[email protected]", "country" : "Germany"} }; so I can access them like: alert(list_all.first_round.name) -> John (Note: the name-values ("name", "email", "color") in the two list-arrays are not quite the same, the number of items in each list-array is limited but not known in advance; I need to serially add only one array to the previous structure each round and there may be any number of rounds, i.e. "third-round" : {...}, "fourth-round" : {...} and so on.) Ultimately, I'd like it to be well-parsed for JSON. I use the jquery library, if that helps.

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  • How to benchmark on multi-core processors

    - by Pascal Cuoq
    I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

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  • Is there a limit for the number of files in a directory on an SD card?

    - by jamesh
    I have a project written for Android devices. It generates a large number of files, each day. These are all text files and images. The app uses a database to reference these files. The app is supposed to clear up these files after a little use (perhaps after a few days), but this process may or may not be working. This is not the subject of this question. Due to a historic accident, the organization of the files are somewhat naive: everything is in the same directory; a .hidden directory which contains a zero byte .nomedia file to prevent the MediaScanner indexing it. Today, I am seeing an error reported: java.io.IOException: Cannot create: /sdcard/.hidden/file-4200.html at java.io.File.createNewFile(File.java:1263) Regarding the sdcard, I see it has plenty of storage left, but counting $ cd /Volumes/NO_NAME/.hidden $ ls | wc -w 9058 Deleting a number of files seems to have allowed the file creation for today to proceed. Regrettably, I did not try touching a new file to try and reproduce the error on a commandline; I also deleted several hundred files rather than a handful. However, my question is: are there hard limits on filesize or number of files in a directory? am I even on the right track here? Nota Bene: The SD card is as-is - i.e. I haven't formatted it, so I would guess it would be a FAT-* format. The FAT-32 format has hard limits of filesize of 2GB (well above the filesizes I am dealing with) and a limit of number of files in the root directory. I am definitely not writing files in the root directory.

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  • Need some ignition in Embedded Systems

    - by Rahul
    I'm very much interested in building applications for Embedded Devices. I'm in my 3rd year Electrical Engineering and I'm passionate about coding, algorithms, Linux OS, etc. And also by Googling I found out that Linux OS is one of the best OSes for Embedded devices(may be/may not be). I want to work for companies which work on mobile applications. I'm a newbie/naive to this domain & my skills include C/C++ & MySQL. I need help to get started in the domain of Embedded Systems; like how/where to start off, Hardware prerequisites, necessary programming skills, also what kind of Embedded Applications etc. I've heard of ARM, firmware, PIC Micorcontrollers; but I don't know anything & just need proper introduction about them. Thanx. P.S: I'm currently reading Bjarne Struotsup's lecture in C++ at Texas A&M University, and one chapter in it describes about Embedded Systems Programming.

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  • Problems initializing a final variable in Java

    - by froadie
    I keep running into slight variations of a problem in Java and it's starting to get to me, and I can't really think of a proper way to get around it. I have an object property that is final, but dynamic. That is, I want the value to be constant once assigned, but the value can be different each runtime. So I declare the class level variable at the beginning of the class - say private final FILE_NAME;. Then, in the constructor, I assign it a value - say FILE_NAME = buildFileName(); The problem begins when I have code in the buildFileName() method that throws an exception. So I try something like this in the constructor: try{ FILE_NAME = buildFileName(); } catch(Exception e){ ... System.exit(1); } Now I have an error - "The blank final field FILE_NAME may not have been initialized." This is where I start to get slightly annoyed at Java's strict compiler. I know that this won't be a problem because if it gets to the catch the program will exit... But the compiler doesn't know that and so doesn't allow this code. If I try to add a dummy assignment to the catch, I get - "The final field FILE_NAME may already have been assigned." I clearly can't assign a default value before the try-catch because I can only assign to it once. Any ideas...?

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  • How to approach parallel processing of messages?

    - by Dan
    I am redesigning the messaging system for my app to use intel threading building blocks and am stumped trying to decide between two possible approaches. Basically, I have a sequence of message objects and for each message type, a sequence of handlers. For each message object, I apply each handler registered for that message objects type. The sequential version would be something like this (pseudocode): for each message in message_sequence <- SEQUENTIAL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The first approach which I am considering processes the message objects in turn (sequentially) and applies the handlers concurrently. Pros: predictable ordering of messages (ie, we are guaranteed a FIFO processing order) (potentially) lower latency of processing each message Cons: more processing resources available than handlers for a single message type (bad parallelization) bad use of processor cache since message objects need to be copied for each handler to use large overhead for small handlers The pseudocode of this approach would be as follows: for each message in message_sequence <- SEQUENTIAL parallel_for each handler in (handler_table for message.type) apply handler to message <- PARALLEL The second approach is to process the messages in parallel and apply the handlers to each message sequentially. Pros: better use of processor cache (keeps the message object local to all handlers which will use it) small handlers don't impose as much overhead (as long as there are other handlers also to be run) more messages are expected than there are handlers, so the potential for parallelism is greater Cons: Unpredictable ordering - if message A is sent before message B, they may both be processed at the same time, or B may finish processing before all of A's handlers are finished (order is non-deterministic) The pseudocode is as follows: parallel_for each message in message_sequence <- PARALLEL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The second approach has more advantages than the first, but non-deterministic ordering is a big disadvantage.. Which approach would you choose and why? Are there any other approaches I should consider (besides the obvious third approach: parallel messages and parallel handlers, which has the disadvantages of both and no real redeeming factors as far as I can tell)? Thanks!

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  • C# Configuration Manager . ConnectionStrings

    - by Yoda
    I have a console app containing an application configuration file containing one connection string as shown below: <configuration> <connectionStrings> <add name="Target" connectionString="server=MYSERVER; Database=MYDB; Integrated Security=SSPI;" /> </connectionStrings> </configuration> When I pass this to my Connection using: ConfigurationManager.ConnectionStrings[1].ToString() I have two values in there, hence using the second in the collection, my question is where is this second coming from? I have checked the Bin version and original and its not mine! Its obviously a system generated one but I have not seen this before? Can anyone enlighten me? The mystery connection string is: data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true This isn't a problem as such I would just like to know why this is occuring? Thanks in advance! For future reference to those who may or may not stumble on this, after discovering the machine.config its become apparent it is bad practice to refer to a config by its index as each stack will potentially be different, which is why "Keys" are used. Cheers all!

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  • C++ operator new, object versions, and the allocation sizes

    - by mizubasho
    Hi. I have a question about different versions of an object, their sizes, and allocation. The platform is Solaris 8 (and higher). Let's say we have programs A, B, and C that all link to a shared library D. Some class is defined in the library D, let's call it 'classD', and assume the size is 100 bytes. Now, we want to add a few members to classD for the next version of program A, without affecting existing binaries B or C. The new size will be, say, 120 bytes. We want program A to use the new definition of classD (120 bytes), while programs B and C continue to use the old definition of classD (100 bytes). A, B, and C all use the operator "new" to create instances of D. The question is, when does the operator "new" know the amount of memory to allocate? Compile time or run time? One thing I am afraid of is, programs B and C expect classD to be and alloate 100 bytes whereas the new shared library D requires 120 bytes for classD, and this inconsistency may cause memory corruption in programs B and C if I link them with the new library D. In other words, the area for extra 20 bytes that the new classD require may be allocated to some other variables by program B and C. Is this assumption correct? Thanks for your help.

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  • Question about WeakHashMap

    - by michael
    Hi, In the Javadoc of "http://java.sun.com/j2se/1.4.2/docs/api/java/util/WeakHashMap.html", it said "Each key object in a WeakHashMap is stored indirectly as the referent of a weak reference. Therefore a key will automatically be removed only after the weak references to it, both inside and outside of the map, have been cleared by the garbage collector." And then Note that a value object may refer indirectly to its key via the WeakHashMap itself; that is, a value object may strongly refer to some other key object whose associated value object, in turn, strongly refers to the key of the first value object. But should not both Key and Value should be used weak reference in WeakHashMap? i.e. if there is low on memory, GC will free the memory held by the value object (since the value object most likely take up more memory than key object in most cases)? And if GC free the Value object, the Key Object can be free as well? Basically, I am looking for a HashMap which will reduce memory usage when there is low memory (GC collects the value and key objects if necessary). Is it possible in Java? Thank you.

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  • Which source control paradigm and solution to embed in a custom editor application?

    - by Greg Harman
    I am building an application that manages a number of custom objects, which may be edited concurrently by multiple users (using different instances of the application). These objects have an underlying serialized representation, and my plan is to persist them (through my application UI) in an external source control system. Of course this implies that my application can check the current version of an object for updates, a merging interface for each object, etc. My question is what source control paradigm(s) and specific solution(s) to support and why. The way I (perhaps naively) see the source control world is three general paradigms: Single-repository, locked access (MS SourceSafe) Single-repository, concurrent access (CVS/SVN) Distributed (Mercurial, Git) I haven't heard of anyone using #1 for quite a number of years, so I am planning to disregard this case altogether (unless I get a compelling argument otherwise). However, I'm at a loss as to whether to support #2 or #3, and which specific implementations. I'm concerned that the use paradigms are subtly different enough that I can't adequately capture basic operations in a single UI. The last bit of information I should convey is that this application is intended to be deployed in a commercial setting, where a source control system may already be in use. I would prefer not to support more than one solution unless it's really a deal-breaker, so wide adoption in a corporate setting is a plus.

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