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• Problems with updates

  - by legospace9876

  I can not update Weather Indicator with Update Manager. This is the terminal log: installArchives() failed: perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "sr_RS.utf_8_latin" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "sr_RS.utf_8_latin" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "sr_RS.utf_8_latin" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "sr_RS.utf_8_latin" are supported and installed on your system. perl: warning: Falling back to the andard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory Setting up indicator-weather (11.11.28-0ubuntu1.1) ... Installing indicator-specific icons... Installing indicator dconf schema... cp: cannot stat `/usr/share/indicator-weather/indicator-weather.gschema.xml': No such file or directory dpkg: error processing indicator-weather (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: indicator-weather Error in function: SystemError: E:Sub-process /usr/bin/dpkg returned an error code (1) Setting up indicator-weather (11.11.28-0ubuntu1.1) ... Installing indicator-specific icons... Installing indicator dconf schema... cp: cannot stat `**/usr/share/indicator-weather/indicator-weather.gschema.xml**': No such file or directory dpkg: error processing indicator-weather (--configure): subprocess installed post-installation script returned error exit status 1 The file that I bold really does not exist. How can I solve this problem?

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• Cloud Computing Architecture Patterns: Don’t Focus on the Client

  - by BuckWoody

  Normally I try to put topics in the positive in other words "Do this" not "Don't do that". Sometimes its clearer to focus on what *not* to do. Popular development processes often start with screen mockups, or user input descriptions. In a scale-out pattern like Cloud Computing on Windows Azure, that's the wrong place to start. Start with the Data    Instead, I recommend that you start with the data that a process requires. That data might be temporary or persisted, but starting with the data and its requirements helps to define not only the storage engine you need but also drives everything from security to the integrity of the application. For instance, assume the requirements show that the user must enter their phone number, and that this datum is used in a contact management system further down the application chain. For that datum, you can determine what data type you need (U.S. only or International?) the security requirements, whether it needs ACID compliance, how it will be searched, indexed and so on. From one small data point you can extrapolate out your options for storing and processing the data. Here's the interesting part, which begins to break the patterns that we've used for decades: all of the data doesn't have the same requirements. The phone number might be best suited for a list, or an element, or a string, with either BASE or ACID requirements, based on how it is used. That means we don't have to dump everything into XML, an RDBMS, a NoSQL engine, or a flat file exclusively. In fact, one record might use all of those depending on the use-case requirements. Next Is Data Management  With the data defined, we can move on to how to store the data. Again, the requirements now dictate whether we need a full relational calculus or set-based operations, or we can choose another method based on the requirements for the data. And breaking another pattern its OK to store in more than once, in more than one location. We do this all the time for reporting systems and Business Intelligence systems, so this is a pattern we need to think about even for OLTP data. Move to Data Transport How does the data get around? We can use a connection-based method, sending the data along a transport to the storage engine, but in some cases we may want to use a cache, a queue, the Service Bus, or Complex Event Processing. Finally, Data Processing Most RDBMS engines, NoSQL, and certainly Big Data engines not only store data, but can process and manipulate it as well. Its doubtful that you'll calculate that phone number right? Well, if you're the phone company, you most certainly will. And so we see that even once we've chosen the data type, storage and engine, the same element can have different computing requirements based on how it is used. Sure, We Need A Front-End At Some Point Not all data is entered by human hands in fact most data isn't. We don't really need a Graphical User Interface (GUI) we need some way for a GUI to get data into and out of the systems listed earlier.   But when we do need to allow users to enter or examine data, that should be left to the GUI that best fits the device the user has. Ever tried to use an application designed for a web browser on a phone? Or one designed for a tablet on a phone? Its usually quite painful. The siren song of "We'll just write one interface for all devices" is strong, and has beguiled many an unsuspecting architect. But they just don't work out.   Instead, focus on the data, its transport and processing. Create API calls or a message system that allows for resilient transport to the device or interface, and let it do what it does best. References Microsoft Architecture Journal:   http://msdn.microsoft.com/en-us/architecture/bb410935.aspx Patterns and Practices:   http://msdn.microsoft.com/en-us/library/ff921345.aspx Windows Azure iOS, Android, Windows 8 Mobile Devices SDK: http://www.windowsazure.com/en-us/develop/mobile/tutorials/get-started-ios/ Windows Azure Facebook SDK: http://ntotten.com/2013/03/14/using-windows-azure-mobile-services-with-the-facebook-sdk-for-windows-phone/

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• perl scripts stdin/pipe reading problem [closed]

  - by user4541

  I have 2 scripts for a task. The 1st outputs lines of data (terminated with RT/LF) to STDOUT now and then. The 2nd keeps reading data from STDIN for further processing in the following way: use strict; my $dataline; while(1) { $dtaline = ""; $dataline = ; until( $dataline ne "") { sleep(1); $dataline = ; } #further processing with a non-empty data line follows # } print "quitting...\n"; I redirect the output from the 1st to the 2nd using pipe as following: perl scrt1 |perl scpt2. But the problem I'm having with these 2 scpts is that it looks like that the 2nd scpt keeps getting the initial load of lines of data from the 1st scpt if there's no data anymore. Wonder if anybody having similar issues can kindly help a bit? Thanks.

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• Event Processed

  - by Antony Reynolds

  Installing Oracle Event Processing 11g Earlier this month I was involved in organizing the Monument Family History Day.  It was certainly a complex event, with dozens of presenters, guides and 100s of visitors.  So with that experience of a complex event under my belt I decided to refresh my acquaintance with Oracle Event Processing (CEP). CEP has a developer side based on Eclipse and a runtime environment. Developer Install The developer install requires several steps (documentation) Download required software Eclipse  (Linux) – It is recommended to use version 3.6.2 (Helios) Install Eclipse Unzip the download into the desired directory Start Eclipse Add Oracle CEP Repository in Eclipse http://download.oracle.com/technology/software/cep-ide/11/ Install Oracle CEP Tools for Eclipse 3.6 You may need to set the proxy if behind a firewall. Modify eclipse.ini If using Windows edit with wordpad rather than notepad Point to 1.6 JVM Insert following lines before –vmargs -vm \PATH_TO_1.6_JDK\jre\bin\javaw.exe Increase PermGen Memory Insert following line at end of file -XX:MaxPermSize=256M Restart eclipse and verify that everything is installed as expected. Server install The server install is very straightforward (documentation).  It is recommended to use the JRockit JDK with CEP so the steps to set up a working CEP server environment are: Download required software JRockit – I used Oracle “JRockit 6 - R28.2.5” which includes “JRockit Mission Control 4.1” and “JRockit Real Time 4.1”. Oracle Event Processor – I used “Complex Event Processing Release 11gR1 (11.1.1.6.0)” Install JRockit Run the JRockit installer, the download is an executable binary that just needs to be marked as executable. Install CEP Unzip the downloaded file Run the CEP installer,  the unzipped file is an executable binary that may need to be marked as executable. Choose a custom install and add the examples if needed. It is not recommended to add the examples to a production environment but they can be helpful in development. Voila The Deed Is Done With CEP installed you are now ready to start a server, if you didn’t install the demoes then you will need to create a domain before starting the server. Once the server is up and running (using startwlevs.sh) you can verify that the visualizer is available on http://hostname:port/wlevs, the default port for the demo domain is 9002. With the server running you can test the IDE by creating a new “Oracle CEP Application Project” and creating a new target environment pointing at your CEP installation. Much easier than organizing a Family History Day!

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• Metric 3d reconstruction

  - by srand

  I'm trying to reconstruct 3D points from 2D image correspondences. My camera is calibrated. The test images are of a checkered cube and correspondences are hand picked. Radial distortion is removed. After triangulation the construction seems to be wrong however. The X and Y values seem to be correct, but the Z values are about the same and do not differentiate along the cube. The 3D points look like as if the points were flattened along the Z-axis. What is going wrong in the Z values? Do the points need to be normalized or changed from image coordinates at any point, say before the fundamental matrix is computed? (If this is too vague I can explain my general process or elaborate on parts)

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• Issues when upgrading gnome-session

  - by Gabriel A. Zorrilla

  I'm having issues since yesterday after an upgrade. GNOME session got messed up somehow and now i cannot install further upgrades nor new apps. Here is what i got from terminal after doing the recommended apt-get install -f; (Reading database ... 166876 files and directories currently installed.) Preparing to replace gnome-session 3.0.1-0ubuntu1~build2 (using .../gnome-session_3.0.2-0ubuntu3~natty1_all.deb) ... Unpacking replacement gnome-session ... dpkg: error processing /var/cache/apt/archives/gnome-session_3.0.2-0ubuntu3~natty1_all.deb (--unpack): trying to overwrite '/usr/share/xsessions/gnome-shell.desktop', which is also in package gnome-shell 3.0.1-0ubuntu1~build1 Errors were encountered while processing: /var/cache/apt/archives/gnome-session_3.0.2-0ubuntu3~natty1_all.deb E: Sub-process /usr/bin/dpkg returned an error code (1) In var/log/apt/history.log, it says: Start-Date: 2011-05-29 17:56:16 Commandline: apt-get -f install Upgrade: gnome-session:amd64 (3.0.1-0ubuntu1~build2, 3.0.2-0ubuntu3~natty1) Error: Sub-process /usr/bin/dpkg returned an error code (1) End-Date: 2011-05-29 17:56:21 No idea what all this means.

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• Getting started with Oracle Database In-Memory Part III - Querying The IM Column Store

  - by Maria Colgan

  In my previous blog posts, I described how to install, enable, and populate the In-Memory column store (IM column store). This weeks post focuses on how data is accessed within the IM column store. Let’s take a simple query “What is the most expensive air-mail order we have received to date?” SELECT Max(lo_ordtotalprice) most_expensive_order FROM lineorderWHERE  lo_shipmode = 5; The LINEORDER table has been populated into the IM column store and since we have no alternative access paths (indexes or views) the execution plan for this query is a full table scan of the LINEORDER table. You will notice that the execution plan has a new set of keywords “IN MEMORY" in the access method description in the Operation column. These keywords indicate that the LINEORDER table has been marked for INMEMORY and we may use the IM column store in this query. What do I mean by “may use”? There are a small number of cases were we won’t use the IM column store even though the object has been marked INMEMORY. This is similar to how the keyword STORAGE is used on Exadata environments. You can confirm that the IM column store was actually used by examining the session level statistics, but more on that later. For now let's focus on how the data is accessed in the IM column store and why it’s faster to access the data in the new column format, for analytical queries, rather than the buffer cache. There are four main reasons why accessing the data in the IM column store is more efficient. 1. Access only the column data needed The IM column store only has to scan two columns – lo_shipmode and lo_ordtotalprice – to execute this query while the traditional row store or buffer cache has to scan all of the columns in each row of the LINEORDER table until it reaches both the lo_shipmode and the lo_ordtotalprice column. 2. Scan and filter data in it's compressed format When data is populated into the IM column it is automatically compressed using a new set of compression algorithms that allow WHERE clause predicates to be applied against the compressed formats. This means the volume of data scanned in the IM column store for our query will be far less than the same query in the buffer cache where it will scan the data in its uncompressed form, which could be 20X larger. 3. Prune out any unnecessary data within each column The fastest read you can execute is the read you don’t do. In the IM column store a further reduction in the amount of data accessed is possible due to the In-Memory Storage Indexes(IM storage indexes) that are automatically created and maintained on each of the columns in the IM column store. IM storage indexes allow data pruning to occur based on the filter predicates supplied in a SQL statement. An IM storage index keeps track of minimum and maximum values for each column in each of the In-Memory Compression Unit (IMCU). In our query the WHERE clause predicate is on the lo_shipmode column. The IM storage index on the lo_shipdate column is examined to determine if our specified column value 5 exist in any IMCU by comparing the value 5 to the minimum and maximum values maintained in the Storage Index. If the value 5 is outside the minimum and maximum range for an IMCU, the scan of that IMCU is avoided. For the IMCUs where the value 5 does fall within the min, max range, an additional level of data pruning is possible via the metadata dictionary created when dictionary-based compression is used on IMCU. The dictionary contains a list of the unique column values within the IMCU. Since we have an equality predicate we can easily determine if 5 is one of the distinct column values or not. The combination of the IM storage index and dictionary based pruning, enables us to only scan the necessary IMCUs. 4. Use SIMD to apply filter predicates For the IMCU that need to be scanned Oracle takes advantage of SIMD vector processing (Single Instruction processing Multiple Data values). Instead of evaluating each entry in the column one at a time, SIMD vector processing allows a set of column values to be evaluated together in a single CPU instruction. The column format used in the IM column store has been specifically designed to maximize the number of column entries that can be loaded into the vector registers on the CPU and evaluated in a single CPU instruction. SIMD vector processing enables the Oracle Database In-Memory to scan billion of rows per second per core versus the millions of rows per second per core scan rate that can be achieved in the buffer cache. I mentioned earlier in this post that in order to confirm the IM column store was used; we need to examine the session level statistics. You can monitor the session level statistics by querying the performance views v$mystat and v$statname. All of the statistics related to the In-Memory Column Store begin with IM. You can see the full list of these statistics by typing: display_name format a30 SELECT display_name FROM v$statname WHERE  display_name LIKE 'IM%'; If we check the session statistics after we execute our query the results would be as follow; SELECT Max(lo_ordtotalprice) most_expensive_order FROM lineorderWHERE lo_shipmode = 5; SELECT display_name FROM v$statname WHERE  display_name IN ('IM scan CUs columns accessed',                        'IM scan segments minmax eligible',                        'IM scan CUs pruned'); As you can see, only 2 IMCUs were accessed during the scan as the majority of the IMCUs (44) in the LINEORDER table were pruned out thanks to the storage index on the lo_shipmode column. In next weeks post I will describe how you can control which queries use the IM column store and which don't. +Maria Colgan

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• How to fix the "Setting locale failed" error while installing vim?

  - by user211775

  When installing vim through Software Center , I get this error installArchives() failed: perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "en_IN.ISO8859-1" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "en_IN.ISO8859-1" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "en_IN.ISO8859-1" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "en_IN.ISO8859-1" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory Setting up install-info (4.13a.dfsg.1-10ubuntu4) ... /etc/environment: line 1: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games: No such file or directory dpkg: error processing install-info (--configure): subprocess installed post-installation script returned error exit status 1 No apport report written because MaxReports is reached already Errors were encountered while processing: install-info Setting up install-info (4.13a.dfsg.1-10ubuntu4) ... /etc/environment: line 1: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games: No such file or directory dpkg: error processing install-info (--configure): subprocess installed post-installation script returned error exit status 1

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• POP Culture

  - by [email protected]

  When we hear the word POP, we normally think of a soft drink, or a soda, while for others, it might be their favourite kind of music. In my case, it's the sound my knee makes when I bend down. Within Oracle though, when we talk about POP, we are referring to the Partner Ordering Portal. The Partner Ordering Portal, or POP as we like to call it, provides AutoVue Partners with a method to submit their orders online. POP offers Partners with up-to-date pricing and licensing information, efficient order processing, as most data is validated on screen, thereby reducing errors and enabling faster processing and, online order status and tracking. POP is not yet available in every country, but it is available in most. Click here to check out the POP home page (OPN Login information required) to see if your country of business is eligible to use POP and, for access to creating an account, watching instructional training viewlets, etc.

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• How and when to use UNIT testing properly

  - by Zebs

  I am an iOS developer. I have read about unit testing and how it is used to test specific pieces of your code. A very quick example has to do with processing JSON data onto a database. The unit test reads a file from the project bundle and executes the method that is in charge of processing JSON data. But I dont get how this is different from actually running the app and testing with the server. So my question might be a bit general, but I honestly dont understand the proper use of unit testing, or even how it is useful; I hope the experienced programmers that surf around StackOverflow can help me. Any help is very much appreciated!

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• Improve your Application Performance with .NET Framework 4.0

  Nice Article on CodeGuru. This processors we use today are quite different from those of just a few years ago, as most processors today provide multiple cores and/or multiple threads. With multiple cores and/or threads we need to change how we tackle problems in code. Yes we can still continue to write code to perform an action in a top down fashion to complete a task. This apprach will continue to work; however, you are not taking advantage of the extra processing power available. The best way to take advantage of the extra cores prior to .NET Framework 4.0 was to create threads and/or utilize the ThreadPool. For many developers utilizing Threads or the ThreadPool can be a little daunting. The .NET 4.0 Framework drastically simplified the process of utilizing the extra processing power through the Task Parallel Library (TPL). This article talks following topics “Data Parallelism”, “Parallel LINQ (PLINQ)” and “Task Parallelism”. span.fullpost {display:none;}

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• Repeated Scene Trees (Java3d / OpenGL)

  - by Jim

  Hello, I want to make a 3d scene that loops around on its self. That is to say, if you keep going in any direction, you will loop back to the other side. My current implementation is so bad, it's embarrassing to admit to it. I redraw the each change twenty-seven times, to make a 3x3x3 scene cube. When the user reaches the end of the middle cube, I jump them over to the other side. Maintaining consistency (let alone performance) is a nightmare. Total Disaster. This doesn't seem like it would be an unusual request, so I'm wondering if anyone knows of a more legit solution. Thanks!

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• Global keyboard states

  - by Petr Abdulin

  I have following idea about processing keyboard input. We capture input in "main" Game class like this: protected override void Update(GameTime gameTime) { this.CurrentKeyboardState = Keyboard.GetState(); // main :Game class logic here base.Update(gameTime); this.PreviousKeyboardState = this.CurrentKeyboardState; } then, reuse keyboard states (which have internal scope) in all other game components. The reasons behind this are 1) minimize keyboard processing load, and 2) reduce "pollution" of all other classes with similar keyboard state variables. Since I'm quite a noob in both game and XNA development, I would like to know if all of this sounds reasonable.

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• libnotfy1(>= 0.4.4) and libnotify1-gtk2.10 for Ubuntu 11.10

  - by Aamir

  I have recently downloaded the latest version of Lotus Symphony 3.0.1 but whenever I try to install it, it shows the following dependencies. Can anybody tell where I can find these dependencies. dpkg: dependency problems prevent configuration of symphony: symphony depends on **libnotify1 (>= 0.4.4)**; however: Package libnotify1 is not installed. symphony depends on **libnotify1-gtk2.10**; however: Package libnotify1-gtk2.10 is not installed. dpkg: error processing symphony (--install): dependency problems - leaving unconfigured Errors were encountered while processing: symphony

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• Random Page Cost and Planning

  - by Dave Jarvis

  A query (see below) that extracts climate data from weather stations within a given radius of a city using the dates for which those weather stations actually have data. The query uses the table's only index, rather effectively: CREATE UNIQUE INDEX measurement_001_stc_idx ON climate.measurement_001 USING btree (station_id, taken, category_id); Reducing the server's configuration value for random_page_cost from 2.0 to 1.1 had a massive performance improvement for the given range (nearly an order of magnitude) because it suggested to PostgreSQL that it should use the index. While the results now return in 5 seconds (down from ~85 seconds), problematic lines remain. Bumping the query's end date by a single year causes a full table scan: sc.taken_start >= '1900-01-01'::date AND sc.taken_end <= '1997-12-31'::date AND How do I persuade PostgreSQL to use the indexes regardless of years between the two dates? (A full table scan against 43 million rows is probably not the best plan.) Find the EXPLAIN ANALYSE results below the query. Thank you! Query SELECT extract(YEAR FROM m.taken) AS year, avg(m.amount) AS amount FROM climate.city c, climate.station s, climate.station_category sc, climate.measurement m WHERE c.id = 5182 AND earth_distance( ll_to_earth(c.latitude_decimal,c.longitude_decimal), ll_to_earth(s.latitude_decimal,s.longitude_decimal)) / 1000 <= 30 AND s.elevation BETWEEN 0 AND 3000 AND s.applicable = TRUE AND sc.station_id = s.id AND sc.category_id = 1 AND sc.taken_start >= '1900-01-01'::date AND sc.taken_end <= '1996-12-31'::date AND m.station_id = s.id AND m.taken BETWEEN sc.taken_start AND sc.taken_end AND m.category_id = sc.category_id GROUP BY extract(YEAR FROM m.taken) ORDER BY extract(YEAR FROM m.taken) 1900 to 1996: Index "Sort (cost=1348597.71..1348598.21 rows=200 width=12) (actual time=2268.929..2268.935 rows=92 loops=1)" " Sort Key: (date_part('year'::text, (m.taken)::timestamp without time zone))" " Sort Method: quicksort Memory: 32kB" " -> HashAggregate (cost=1348586.56..1348590.06 rows=200 width=12) (actual time=2268.829..2268.886 rows=92 loops=1)" " -> Nested Loop (cost=0.00..1344864.01 rows=744510 width=12) (actual time=0.807..2084.206 rows=134893 loops=1)" " Join Filter: ((m.taken >= sc.taken_start) AND (m.taken <= sc.taken_end) AND (sc.station_id = m.station_id))" " -> Nested Loop (cost=0.00..12755.07 rows=1220 width=18) (actual time=0.502..521.937 rows=23 loops=1)" " Join Filter: ((sec_to_gc(cube_distance((ll_to_earth((c.latitude_decimal)::double precision, (c.longitude_decimal)::double precision))::cube, (ll_to_earth((s.latitude_decimal)::double precision, (s.longitude_decimal)::double precision))::cube)) / 1000::double precision) <= 30::double precision)" " -> Index Scan using city_pkey1 on city c (cost=0.00..2.47 rows=1 width=16) (actual time=0.014..0.015 rows=1 loops=1)" " Index Cond: (id = 5182)" " -> Nested Loop (cost=0.00..9907.73 rows=3659 width=34) (actual time=0.014..28.937 rows=3458 loops=1)" " -> Seq Scan on station_category sc (cost=0.00..970.20 rows=3659 width=14) (actual time=0.008..10.947 rows=3458 loops=1)" " Filter: ((taken_start >= '1900-01-01'::date) AND (taken_end <= '1996-12-31'::date) AND (category_id = 1))" " -> Index Scan using station_pkey1 on station s (cost=0.00..2.43 rows=1 width=20) (actual time=0.004..0.004 rows=1 loops=3458)" " Index Cond: (s.id = sc.station_id)" " Filter: (s.applicable AND (s.elevation >= 0) AND (s.elevation <= 3000))" " -> Append (cost=0.00..1072.27 rows=947 width=18) (actual time=6.996..63.199 rows=5865 loops=23)" " -> Seq Scan on measurement m (cost=0.00..25.00 rows=6 width=22) (actual time=0.000..0.000 rows=0 loops=23)" " Filter: (m.category_id = 1)" " -> Bitmap Heap Scan on measurement_001 m (cost=20.79..1047.27 rows=941 width=18) (actual time=6.995..62.390 rows=5865 loops=23)" " Recheck Cond: ((m.station_id = sc.station_id) AND (m.taken >= sc.taken_start) AND (m.taken <= sc.taken_end) AND (m.category_id = 1))" " -> Bitmap Index Scan on measurement_001_stc_idx (cost=0.00..20.55 rows=941 width=0) (actual time=5.775..5.775 rows=5865 loops=23)" " Index Cond: ((m.station_id = sc.station_id) AND (m.taken >= sc.taken_start) AND (m.taken <= sc.taken_end) AND (m.category_id = 1))" "Total runtime: 2269.264 ms" 1900 to 1997: Full Table Scan "Sort (cost=1370192.26..1370192.76 rows=200 width=12) (actual time=86165.797..86165.809 rows=94 loops=1)" " Sort Key: (date_part('year'::text, (m.taken)::timestamp without time zone))" " Sort Method: quicksort Memory: 32kB" " -> HashAggregate (cost=1370181.12..1370184.62 rows=200 width=12) (actual time=86165.654..86165.736 rows=94 loops=1)" " -> Hash Join (cost=4293.60..1366355.81 rows=765061 width=12) (actual time=534.786..85920.007 rows=139721 loops=1)" " Hash Cond: (m.station_id = sc.station_id)" " Join Filter: ((m.taken >= sc.taken_start) AND (m.taken <= sc.taken_end))" " -> Append (cost=0.00..867005.80 rows=43670150 width=18) (actual time=0.009..79202.329 rows=43670079 loops=1)" " -> Seq Scan on measurement m (cost=0.00..25.00 rows=6 width=22) (actual time=0.001..0.001 rows=0 loops=1)" " Filter: (category_id = 1)" " -> Seq Scan on measurement_001 m (cost=0.00..866980.80 rows=43670144 width=18) (actual time=0.008..73312.008 rows=43670079 loops=1)" " Filter: (category_id = 1)" " -> Hash (cost=4277.93..4277.93 rows=1253 width=18) (actual time=534.704..534.704 rows=25 loops=1)" " -> Nested Loop (cost=847.87..4277.93 rows=1253 width=18) (actual time=415.837..534.682 rows=25 loops=1)" " Join Filter: ((sec_to_gc(cube_distance((ll_to_earth((c.latitude_decimal)::double precision, (c.longitude_decimal)::double precision))::cube, (ll_to_earth((s.latitude_decimal)::double precision, (s.longitude_decimal)::double precision))::cube)) / 1000::double precision) <= 30::double precision)" " -> Index Scan using city_pkey1 on city c (cost=0.00..2.47 rows=1 width=16) (actual time=0.012..0.014 rows=1 loops=1)" " Index Cond: (id = 5182)" " -> Hash Join (cost=847.87..1352.07 rows=3760 width=34) (actual time=6.427..35.107 rows=3552 loops=1)" " Hash Cond: (s.id = sc.station_id)" " -> Seq Scan on station s (cost=0.00..367.25 rows=7948 width=20) (actual time=0.004..23.529 rows=7949 loops=1)" " Filter: (applicable AND (elevation >= 0) AND (elevation <= 3000))" " -> Hash (cost=800.87..800.87 rows=3760 width=14) (actual time=6.416..6.416 rows=3552 loops=1)" " -> Bitmap Heap Scan on station_category sc (cost=430.29..800.87 rows=3760 width=14) (actual time=2.316..5.353 rows=3552 loops=1)" " Recheck Cond: (category_id = 1)" " Filter: ((taken_start >= '1900-01-01'::date) AND (taken_end <= '1997-12-31'::date))" " -> Bitmap Index Scan on station_category_station_category_idx (cost=0.00..429.35 rows=6376 width=0) (actual time=2.268..2.268 rows=6339 loops=1)" " Index Cond: (category_id = 1)" "Total runtime: 86165.936 ms"

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• Improve your Application Performance with .NET Framework 4.0

  Nice Article on CodeGuru. This processors we use today are quite different from those of just a few years ago, as most processors today provide multiple cores and/or multiple threads. With multiple cores and/or threads we need to change how we tackle problems in code. Yes we can still continue to write code to perform an action in a top down fashion to complete a task. This apprach will continue to work; however, you are not taking advantage of the extra processing power available. The best way to take advantage of the extra cores prior to .NET Framework 4.0 was to create threads and/or utilize the ThreadPool. For many developers utilizing Threads or the ThreadPool can be a little daunting. The .NET 4.0 Framework drastically simplified the process of utilizing the extra processing power through the Task Parallel Library (TPL). This article talks following topics “Data Parallelism”, “Parallel LINQ (PLINQ)” and “Task Parallelism”. span.fullpost {display:none;}

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• How can I successfully perform hidden line removal after pass through FBO?

  - by Brett

  Hi All, I'm trying to perform hidden line removal using polygon offset fill. The code works perfectly if I render directly to the window buffer but fails to draw the lines when passed through a FBO as shown below The code I use to draw the objects void drawCubes (GLboolean removeHiddenLines) { glLineWidth(2.0); glPushMatrix(); camera.ApplyCameraTransform(); for(int i = 0; i < 50; i ++){ glPushMatrix(); cube[i].updatePerspective(); glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); glColor3f(1.0,1.0,1.0); cube[i].draw(); glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); if(removeHiddenLines){ glEnable(GL_POLYGON_OFFSET_FILL); glPolygonOffset(1.0, 1.0); glColor3f(1.0, 0.0, 0.0); //fill polygons for hidden line removal cube[i].draw(); glDisable(GL_POLYGON_OFFSET_FILL); } glPopMatrix(); } glPopMatrix(); } For this example, the first pass involves rendering to both the window buffer and a FBO. void firstPass() { glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glViewport(0, 0, fboWidth, fboHeight); glEnable(GL_DEPTH_TEST); glDisable(GL_TEXTURE_2D); drawParticleView(GL_TRUE); glDisable(GL_DEPTH_TEST); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebufferID[0]); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glViewport(0, 0, fboWidth, fboHeight); glEnable(GL_DEPTH_TEST); glDisable(GL_TEXTURE_2D); drawParticleView(GL_TRUE); glDisable(GL_DEPTH_TEST); } Second pass renders FBO back to window buffer. void secondPass() { glEnable(GL_TEXTURE_2D); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); glBindTexture(GL_TEXTURE_2D, renderTextureID[0]); glViewport(fboWidth, 0, fboWidth, fboHeight); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glBegin(GL_QUADS); glTexCoord2i(0, 0); glVertex2f(-1.0f, -1.0f); glTexCoord2i(1, 0); glVertex2f(1.0f, -1.0f); glTexCoord2i(1, 1); glVertex2f(1.0f, 1.0f); glTexCoord2i(0, 1); glVertex2f(-1.0f, 1.0f); glEnd(); glDisable(GL_TEXTURE_2D); } I don't understand why the two views wouldn't be the same? Am I missing something (obviously I am)? Thanks

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• Mysql-server-5.5 broken after update

  - by WalrusTusks

  Using Ubuntu 12.04, desktop, I had LAMP installed on my computer, and was using it as a server. However, after doing the upgrades one day, apt-get throws an error that mysql-server can't be configured, as it depends on another package: jay@rumbles:~$ sudo apt-get dist-upgrade Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies: mysql-server-5.5 : Depends: mysql-server-core-5.5 (= 5.5.22-0ubuntu1) but 5.5.24-0ubuntu0.12.04.1 is installed E: Unmet dependencies. Try using -f ` jay@rumbles:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree Reading state information... Done Correcting dependencies... Done The following extra packages will be installed: mysql-server-5.5 Suggested packages: tinyca mailx The following packages will be upgraded: mysql-server-5.5 1 upgraded, 0 newly installed, 0 to remove and 35 not upgraded. 2 not fully installed or removed. Need to get 0 B/8,821 kB of archives. After this operation, 2,048 B of additional disk space will be used. Do you want to continue [Y/n]? y dpkg: dependency problems prevent configuration of mysql-server-5.5: mysql-server-5.5 depends on mysql-server-core-5.5 (= 5.5.22-0ubuntu1); however: Version of mysql-server-core-5.5 on system is 5.5.24-0ubuntu0.12.04.1. dpkg: error processing mysql-server-5.5 (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of mysql-server: mysql-server depends on mysql-server-5.5; however: No apport report written because the error message indicates its a followup error from a previous failure. No apport report written because the error message indicates its a followup error from a previous failure. Package mysql-server-5.5 is not configured yet. dpkg: error processing mysql-server (--configure): dependency problems - leaving unconfigured Errors were encountered while processing: mysql-server-5.5 mysql-server E: Sub-process /usr/bin/dpkg returned an error code (1) How can I fix this?

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• Depends libntfs10 error while installing testdisk

  - by user260223

  I want to install testdisk to ubuntu 10.04 LTS but i'm getting an error. Any help? Here is the output: # sudo apt-get install testdisk Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: testdisk: Depends: libntfs10 (>= 2.0.0) but it is not installable E: Broken packages I also tried: wget http://launchpadlibrarian.net/40386584/libntfs10_2.0.0-1ubuntu4_i386.deb; sudo dpkg -i *.deb And i get this error: dpkg: error processing libntfs10_2.0.0-1ubuntu4_i386.deb (--install): package architecture (i386) does not match system (amd64) Errors were encountered while processing: libntfs10_2.0.0-1ubuntu4_i386.deb

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• Does anyone know how to appropriately deal with user timezones in rails 2.3?

  - by Amazing Jay

  We're building a rails app that needs to display dates (and more importantly, calculate them) in multiple timezones. Can anyone point me towards how to work with user timezones in rails 2.3(.5 or .8) The most inclusive article I've seen detailing how user time zones are supposed to work is here: http://wiki.rubyonrails.org/howtos/time-zones... although it is unclear when this was written or for what version of rails. Specifically it states that: "Time.zone - The time zone that is actually used for display purposes. This may be set manually to override config.time_zone on a per-request basis." Keys terms being "display purposes" and "per-request basis". Locally on my machine, this is true. However on production, neither are true. Setting Time.zone persists past the end of the request (to all subsequent requests) and also affects the way AR saves to the DB (basically treating any date as if it were already in UTC even when its not), thus saving completely inappropriate values. We run Ruby Enterprise Edition on production with passenger. If this is my problem, do we need to switch to JRuby or something else? To illustrate the problem I put the following actions in my ApplicationController right now: def test p_time = Time.now.utc s_time = Time.utc(p_time.year, p_time.month, p_time.day, p_time.hour) logger.error "TIME.ZONE" + Time.zone.inspect logger.error ENV['TZ'].inspect logger.error p_time.inspect logger.error s_time.inspect jl = JunkLead.create! jl.date_at = s_time logger.error s_time.inspect logger.error jl.date_at.inspect jl.save! logger.error s_time.inspect logger.error jl.date_at.inspect render :nothing => true, :status => 200 end def test2 Time.zone = 'Mountain Time (US & Canada)' logger.error "TIME.ZONE" + Time.zone.inspect logger.error ENV['TZ'].inspect render :nothing => true, :status => 200 end def test3 Time.zone = 'UTC' logger.error "TIME.ZONE" + Time.zone.inspect logger.error ENV['TZ'].inspect render :nothing => true, :status => 200 end and they yield the following: Processing ApplicationController#test (for 98.202.196.203 at 2010-12-24 22:15:50) [GET] TIME.ZONE#<ActiveSupport::TimeZone:0x2c57a68 @tzinfo=#<TZInfo::DataTimezone: Etc/UTC>, @name="UTC", @utc_offset=0> nil Fri Dec 24 22:15:50 UTC 2010 Fri Dec 24 22:00:00 UTC 2010 Fri Dec 24 22:00:00 UTC 2010 Fri, 24 Dec 2010 22:00:00 UTC +00:00 Fri Dec 24 22:00:00 UTC 2010 Fri, 24 Dec 2010 22:00:00 UTC +00:00 Completed in 21ms (View: 0, DB: 4) | 200 OK [http://www.dealsthatmatter.com/test] Processing ApplicationController#test2 (for 98.202.196.203 at 2010-12-24 22:15:53) [GET] TIME.ZONE#<ActiveSupport::TimeZone:0x2c580a8 @tzinfo=#<TZInfo::DataTimezone: America/Denver>, @name="Mountain Time (US & Canada)", @utc_offset=-25200> nil Completed in 143ms (View: 1, DB: 3) | 200 OK [http://www.dealsthatmatter.com/test2] Processing ApplicationController#test (for 98.202.196.203 at 2010-12-24 22:15:59) [GET] TIME.ZONE#<ActiveSupport::TimeZone:0x2c580a8 @tzinfo=#<TZInfo::DataTimezone: America/Denver>, @name="Mountain Time (US & Canada)", @utc_offset=-25200> nil Fri Dec 24 22:15:59 UTC 2010 Fri Dec 24 22:00:00 UTC 2010 Fri Dec 24 22:00:00 UTC 2010 Fri, 24 Dec 2010 15:00:00 MST -07:00 Fri Dec 24 22:00:00 UTC 2010 Fri, 24 Dec 2010 15:00:00 MST -07:00 Completed in 20ms (View: 0, DB: 4) | 200 OK [http://www.dealsthatmatter.com/test] Processing ApplicationController#test3 (for 98.202.196.203 at 2010-12-24 22:16:03) [GET] TIME.ZONE#<ActiveSupport::TimeZone:0x2c57a68 @tzinfo=#<TZInfo::DataTimezone: Etc/UTC>, @name="UTC", @utc_offset=0> nil Completed in 17ms (View: 0, DB: 2) | 200 OK [http://www.dealsthatmatter.com/test3] Processing ApplicationController#test (for 98.202.196.203 at 2010-12-24 22:16:04) [GET] TIME.ZONE#<ActiveSupport::TimeZone:0x2c57a68 @tzinfo=#<TZInfo::DataTimezone: Etc/UTC>, @name="UTC", @utc_offset=0> nil Fri Dec 24 22:16:05 UTC 2010 Fri Dec 24 22:00:00 UTC 2010 Fri Dec 24 22:00:00 UTC 2010 Fri, 24 Dec 2010 22:00:00 UTC +00:00 Fri Dec 24 22:00:00 UTC 2010 Fri, 24 Dec 2010 22:00:00 UTC +00:00 Completed in 151ms (View: 0, DB: 4) | 200 OK [http://www.dealsthatmatter.com/test] It should be clear above that the 2nd call to /test shows Time.zone set to Mountain, even though it shouldn't. Additionally, checking the database reveals that the test action when run after test2 saved a JunkLead record with a date of 2010-12-22 15:00:00, which is clearly wrong.

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• Which programming language for text editing?

  - by Ali

  I need a programming language for text editing and processing (replace, formatting, regex, string comparison, word processing, text analysis, etc). Which programming language is more powerful and has more functions for this purpose? Since I work PHP for my web projects, I currently use PHP; but the fact is that PHP is a scripting language for web applications, my current project is offline. I am curious if other programming languages such as Perl, Python, C, C++, Java, etc have more functionality for this purpose, and worth of shifting the project?

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• C#: Handling Notifications: inheritance, events, or delegates?

  - by James Michael Hare

  Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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• error with slap.d while installing any new software

  - by ali haider

  I am trying to install wireshark (this issue is not specific to wireshark) on my ubuntu box and I keep getting the following error for slap.d: Setting up slapd (2.4.23-6ubuntu6.1) ... Creating initial configuration... mkdir: cannot create directory `/etc/ldap/slapd.d': File exists dpkg: error processing slapd (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: slapd Besides uninstalling or trying to update open LDAP or slap.d, is there any other action that can be taken to resolve this issue? I am trying the install as root user & I have tried moving the slap.d conf file so far but without any luck. Any thoughts on troubleshooting/resolving this issue will be quite welcome. thank in advance

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• Can't install drivers for Epson wp-4530

  - by Rick

  It looks like it's installing ok then I get an error: (Reading database ... 177199 files and directories currently installed.) Unpacking epson-inkjet-printer-escpr:i386 (from .../epson-inkjet-printer-escpr_1.3.0-1lsb3.2_i386.deb) ... dpkg: dependency problems prevent configuration of epson-inkjet-printer-escpr:i386: epson-inkjet-printer-escpr:i386 depends on lsb (>= 3.2). dpkg: error processing epson-inkjet-printer-escpr:i386 (--install): dependency problems - leaving unconfigured Errors were encountered while processing: epson-inkjet-printer-escpr:i386 Can anyone help me with this? Tried install under linux mint 14 and ubuntu 12.04 same problem. Tried installing using cups and Software center. Driver is from http://download.ebz.epson.net/dsc/search/01/search/?OSC=LX which is only driver site I can find for this printer Please help

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• Cool examples of procedural pixel shader effects?

  - by Robert Fraser

  What are some good examples of procedural/screen-space pixel shader effects? No code necessary; just looking for inspiration. In particular, I'm looking for effects that are not dependent on geometry or the rest of the scene (would look okay rendered alone on a quad) and are not image processing (don't require a "base image", though they can incorporate textures). Multi-pass or single-pass is fine. Screenshots or videos would be ideal, but ideas work too. Here are a few examples of what I'm looking for (all from the RenderMonkey samples): PS - I'm aware of this question; I'm not asking for a source of actual shader implementations but instead for some inspirational ideas -- and the ones at the NVIDIA Shader Library mostly require a scene or are image processing effects. EDIT: this is an open-ended question and I wish there was a good way to split the bounty. I'll award the rep to the best answer on the last day.

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