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  • What file format can I use to output a formatted text file straight from a program without having the markup be too complicated?

    - by Matt
    Premise: I am parsing a file that is quite nearly XML, but not quite. From this file I would like to extract data and output in a file that a user could open up in some program and read. To make the data reasonable, I would almost certainly need to format the text. In case it matters, I will probably be using Java to write the program. Problem: I cannot find a file format that supports formatting without having terribly complex rules and encoding problems. Attempts: I looked into a basic .txt extension first, but it does not have enough formatting advantage. I then tried a .rtf extension, but the rules for outputting text seem to be terribly complicated. It was then suggested that I used XML, but I do not understand how this file would be viewed. This appears to be probably the best solution, but I don't understand much about it. Perhaps somebody could shed some light here. In Other Words: Could somebody suggest and easy to use file format and/or shed some light on how to use XML for text formatting and viewing?

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  • Searching Natural Language Sentence Structure

    - by Cerin
    What's the best way to store and search a database of natural language sentence structure trees? Using OpenNLP's English Treebank Parser, I can get fairly reliable sentence structure parsings for arbitrary sentences. What I'd like to do is create a tool that can extract all the doc strings from my source code, generate these trees for all sentences in the doc strings, store these trees and their associated function name in a database, and then allow a user to search the database using natural language queries. So, given the sentence "This uploads files to a remote machine." for the function upload_files(), I'd have the tree: (TOP (S (NP (DT This)) (VP (VBZ uploads) (NP (NNS files)) (PP (TO to) (NP (DT a) (JJ remote) (NN machine)))) (. .))) If someone entered the query "How can I upload files?", equating to the tree: (TOP (SBARQ (WHADVP (WRB How)) (SQ (MD can) (NP (PRP I)) (VP (VB upload) (NP (NNS files)))) (. ?))) how would I store and query these trees in a SQL database? I've written a simple proof-of-concept script that can perform this search using a mix of regular expressions and network graph parsing, but I'm not sure how I'd implement this in a scalable way. And yes, I realize my example would be trivial to retrieve using a simple keyword search. The idea I'm trying to test is how I might take advantage of grammatical structure, so I can weed-out entries with similar keywords, but a different sentence structure. For example, with the above query, I wouldn't want to retrieve the entry associated with the sentence "Checks a remote machine to find a user that uploads files." which has similar keywords, but is obviously describing a completely different behavior.

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  • Managing project configurations in VS 2010

    - by Toby
    I'm working on a solution with multiple projects (class libraries, interop, web application, etc) in VS2010. For the web application, I would like to take advantage of the config transformations in VS2010, so at one point I added configurations for each of our environments: Development, Test, Production, and so on. Some time later, after having rearranged the project layout, I noticed that some projects show all of the configurations in the properties page dropdown. Some projects (added since I did that setup) show only the standard Debug & Release configurations. Once I realized that this was going to make build configurations worse, not better, I decided to remove all of the extra configurations I had added. I've removed all of the various configuration options from the solution, but the projects that had the alternate configuration options still have them, and I can't figure out how to get rid of them in individual projects. Also, now that I see that not all projects have to have the same configurations, I would like to create my environmental configurations at the solution level, and in the web application project (for the config transforms), but leave all of the class libraries with the basic Debug/Release configurations. I've been unable to find any tool in the UI, or any information on the 'Net, concerning how to set up such a thing. So, in short, what's the best/easiest way to manage configurations at the project level in VS2010?

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  • Can one connection get details of another? Or, how can I get the most detailed pending transaction

    - by bob-the-destroyer
    Is there a Mysql statement which provides full details of any other open connection or user? For this particular case, on myisam tables specifically. Looking at Mysql's SHOW TABLE STATUS documentation, it's missing some very important information for my purpose. For example: remote odbc connection one is inserting several thousand records, which due to a slow connection speed can take up to an hour. Tcp connection two, using PHP on the server's localhost, is running select queries with aggregate functions on that data. Before allowing connection two to run those queries, I'd like connection two to first check to make sure there's no pending inserts on any other connection on those specific tables so it can instead wait until all data is available. If the table is currently being written to, I'd like to spit back to the user of connection two an approximation of how much longer to wait based on the number of pending inserts. Ideally by table, I'd like to get back using a query the timestamp when connection one began the write, total inserts left to be done, and total inserts already completed. Instead of insert counts, even knowing number of bytes written and left to write would work just fine here. Obviously since connection two is a tcp connection via a PHP script, all I can really use in that script is some sort of query. I suppose if I have to, since it is on localhost, I can exec() it if the only way is by a mysql command line option that outputs this info, but I'd rather not. I suppose I could simply update a custom-made transaction log before and after this massive insert task which the PHP script can check, but hopefully there's already a built-in Mysql feature I can take advantage of.

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  • How to make use of Grails Dependencies in your IDE

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

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  • How to use MySQL geospatial extensions with spherical geometries

    - by Joshua
    Hi Everyone, I would like to store thousands of latitude/longitude points in a MySQL db. I was successful at setting up the tables and adding the data using the geospatial extensions where the column 'coord' is a Point(lat, lng). Problem: I want to quickly find the 'N' closest entries to latitude 'X' degrees and longitude 'Y' degrees. Since the Distance() function has not yet been implemented, I used GLength() function to calculate the distance between (X,Y) and each of the entries, sorting by ascending distance, and limiting to 'N' results. The problem is that this is not calculating shortest distance with spherical geometry. Which means if Y = 179.9 degrees, the list of closest entries will only include longitudes of starting at 179.9 and decreasing even though closer entries exist with longitudes increasing from -179.9. How does one typically handle the discontinuity in longitude when working with spherical geometries in databases? There has to be an easy solution to this, but I must just be searching for the wrong thing because I have not found anything helpful. Should I just forget the GLength() function and create my own function for calculating angular separation? If I do this, will it still be fast and take advantage of the geospatial extensions? Thanks! josh UPDATE: This is exactly what I am describing above. However, it is only for SQL Server. Apparently SQL Server has a Geometry and Geography datatypes. The geography does exactly what I need. Is there something similar in MySQL?

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  • Are there good reasons not to use an ORM?

    - by hangy
    During my apprenticeship, I have used NHibernate for some smaller projects which I mostly coded and designed on my own. Now, before starting some bigger project, the discussion arose how to design data access and whether or not to use an ORM layer. As I am still in my apprenticeship and still consider myself a beginner in enterprise programming, I did not really try to push in my opinion, which is that using an object relational mapper to the database can ease development quite a lot. The other coders in the development team are much more experienced than me, so I think I will just do what they say. :-) However, I do not completely understand two of the main reasons for not using NHibernate or a similar project: One can just build one’s own data access objects with SQL queries and copy those queries out of Microsoft SQL Server Management Studio. Debugging an ORM can be hard. So, of course I could just build my data access layer with a lot of SELECTs etc, but here I miss the advantage of automatic joins, lazy-loading proxy classes and a lower maintenance effort if a table gets a new column or a column gets renamed. (Updating numerous SELECT, INSERT and UPDATE queries vs. updating the mapping config and possibly refactoring the business classes and DTOs.) Also, using NHibernate you can run into unforeseen problems if you do not know the framework very well. That could be, for example, trusting the Table.hbm.xml where you set a string’s length to be automatically validated. However, I can also imagine similar bugs in a “simple” SqlConnection query based data access layer. Finally, are those arguments mentioned above really a good reason not to utilise an ORM for a non-trivial database based enterprise application? Are there probably other arguments they/I might have missed? (I should probably add that I think this is like the first “big” .NET/C# based application which will require teamwork. Good practices, which are seen as pretty normal on Stack Overflow, such as unit testing or continuous integration, are non-existing here up to now.)

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  • Real time location tracking - windows program or browser based?

    - by mawg
    I want to track a few hundred, maybe a few thousand people in real time. Let's say that the hardware aspects are sorted out and I can get the data into a database. Now, I want to get it out and show it, in real-time. Weeeell ... "real-enough" time. Let's say that I want to draw a floorplan of a building and plot everyone every 1 to 5 seconds. (I might want to show only certain "kinds" of people at the click of a button; I will need datamining, etc, but let's stick with the worse case scenario). I am comfortable enough with PHP, though not this sort of thing. I personally would be happier with a windows app coded in Delphi, but the trend seems to be to make everything browser based. So, the question, I guess is whether a browser can handle this and whether there are compelling arguments for a windows-based or browser-based solution. If browser-based can handle this (displaying a few thousand data-points a second), and there are no overwhelming arguments for windows then I guess I will go for browser-based and learn a few new tricks. The obvious advantage being that I could also re-use a large part of my code for (vehicle) tracking on Google maps.

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  • How to improve Visual C++ compilation times?

    - by dtrosset
    I am compiling 2 C++ projects in a buildbot, on each commit. Both are around 1000 files, one is 100 kloc, the other 170 kloc. Compilation times are very different from gcc (4.4) to Visual C++ (2008). Visual C++ compilations for one project take in the 20 minutes. They cannot take advantage of the multiple cores because a project depend on the other. In the end, a full compilation of both projects in Debug and Release, in 32 and 64 bits takes more than 2 1/2 hours. gcc compilations for one project take in the 4 minutes. It can be parallelized on the 4 cores and takes around 1 min 10 secs. All 8 builds for 4 versions (Debug/Release, 32/64 bits) of the 2 projects are compiled in less than 10 minutes. What is happening with Visual C++ compilation times? They are basically 5 times slower. What is the average time that can be expected to compile a C++ kloc? Mine are 7 s/kloc with vc++ and 1.4 s/kloc with gcc. Can anything be done to speed-up compilation times on Visual C++?

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  • Putting all methods in class definition

    - by Amnon
    When I use the pimpl idiom, is it a good idea to put all the methods definitions inside the class definition? For example: // in A.h class A { class impl; boost::scoped_ptr<impl> pimpl; public: A(); int foo(); } // in A.cpp class A::impl { // method defined in class int foo() { return 42; } // as opposed to only declaring the method, and defining elsewhere: float bar(); }; A::A() : pimpl(new impl) { } int A::foo() { return pimpl->foo(); } As far as I know, the only problems with putting a method definition inside a class definition is that (1) the implementation is visible in files that include the class definition, and (2) the compiler may make the method inline. These are not problems in this case since the class is defined in a private file, and inlining has no effect since the methods are called in only one place. The advantage of putting the definition inside the class is that you don't have to repeat the method signature. So, is this OK? Are there any other issues to be aware of?

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  • php convert european datetime to mysql datetime

    - by Mathlight
    I'm really stuck with this problem. I've got an datetime string like this: 28-06-14 11:01:00 I'm trying to convert it to 2014-06-28 11:01:00 so that i can insert it into the database ( with field type datetime. I've tryed multiple things like this: $datumHolder = new DateTime($data['datum'], new DateTimeZone('Europe/Amsterdam')); $datum1 = $datumHolder -> format("Y-m-d H:i:s"); $datum2 = date( 'Y-m-d', strtotime(str_replace('-', '/', $data['datum']) ) ); $datum3 = DateTime::createFromFormat( 'Y-m-d-:Hi:s', $data['datum']); This is the output i get: datum1: 2028-06-14 11:01:00 datum2: 1970-01-01 And i get an error for datum3: echo "datum3: " . $datum3->format( 'Y-m-d H:i:s'); . '<br />'; Call to a member function format() on a non-object So my question is very clear... What am I doing wrong / how to get this working? Thanks in advantage guys! I know that this question is asked many, many times... But whatever i try, i can't get it working...

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  • Linq-to-XML explicit casting in a generic method

    - by vlad
    I've looked for a similar question, but the only one that was close didn't help me in the end. I have an XML file that looks like this: <Fields> <Field name="abc" value="2011-01-01" /> <Field name="xyz" value="" /> <Field name="tuv" value="123.456" /> </Fields> I'm trying to use Linq-to-XML to get the values from these fields. The values can be of type Decimal, DateTime, String and Int32. I was able to get the fields one by one using a relatively simple query. For example, I'm getting the 'value' from the field with the name 'abc' using the following: private DateTime GetValueFromAttribute(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == "abc" select (DateTime)field.Attribute("value")).FirstOrDefault() } this is placed in a separate function that simply returns this value, and everything works fine (since I know that there is only one element with the name attribute set to 'abc'). however, since I have to do this for decimals and integers and dates, I was wondering if I can make a generic function that works in all cases. this is where I got stuck. here's what I have so far: private T GetValueFromAttribute<T>(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == attName select (T)field.Attribute("value").Value).FirstOrDefault(); } this doesn't compile because it doesn't know how to convert from String to T. I tried boxing and unboxing (i.e. select (T) (Object) field.Attribute("value").Value but that throws a runtime Specified cast is not valid exception as it's trying to convert the String to a DateTime, for instance. Is this possible in a generic function? can I put a constraint on the generic function to make it work? or do I have to have separate functions to take advantage of Linq-to-XML's explicit cast operators?

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  • Codeigniter Inserting Multidimensional Array as rows in MySQL

    - by RisingSun
    Please Refer to this question I asked Codeigniter Insert Multiple Rows in SQL To restate <tr> <td><input type="text" name="user[0][name]" value=""></td> <td><input type="text" name="user[0][address]" value=""><br></td> <td><input type="text" name="user[0][age]" value=""></td> <td><input type="text" name="user[0][email]" value=""></td> </tr> <tr> <td><input type="text" name="user[1][name]" value=""></td> <td><input type="text" name="user[1][address]" value=""><br></td> <td><input type="text" name="user[1][age]" value=""></td> <td><input type="text" name="user[1][email]" value=""></td> </tr> .......... Can Be Inserted into MySQL as this foreach($_POST['user'] as $user) { $this->db->insert('mytable', $user); } This results in multiple MySQL queries. Is it possible to optimise it further, so that the insert occurs in one query Something like this insert multiple rows via a php array into mysql but taking advantage of codeigniters simpler syntax. Thanks

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  • What legal disclaimer do you use?

    - by Egwor
    I'm working on some code at the moment, but I was wondering what legal disclaimers you have? This is for some work that I'm providing to a friend for free. This isn't open source since there's competitive advantage in the internal workings of the program. I was thinking of something like: Copyright 2008 Egwor.com All rights reserved. Except as contained in this notice, the name(s) of the above copyright holders shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. What do you use?

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  • How would you organize this in asp.net mvc?

    - by chobo
    I have an asp.net mvc 2.0 application that contains Areas/Modules like calendar, admin, etc... There may be cases where more than one area needs to access the same Repo, so I am not sure where to put the Data Access Layers and Repositories. First Option: Should I create Data Access Layer files (Linq to SQL in my case) with their accompanying Repositories for each area, so each area only contains the Tables, and Repositories needed by those areas. The benefit is that everything needed to run that module is one place, so it is more encapsulated (in my mind anyway). The downside is that I may have duplicate queries, because other modules may use the same query. Second Option Or, would it be better to place the DAL and Repositories outside the Area's and treat them as Global? The advantage is I won't have any duplicate queries, but I may be loading a lot of unnecessary queries and DAL tables up for certain modules. It is also more work to reuse or modify these modules for future projects (though the chance of reusing them is slim to none :)) Which option makes more sense? If someone has a better way I'd love to hear it. Thanks!

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  • Practical non-image based CAPTCHA approaches?

    - by Jeff Atwood
    It looks like we'll be adding CAPTCHA support to Stack Overflow. This is necessary to prevent bots, spammers, and other malicious scripted activity. We only want human beings to post or edit things here! We'll be using a JavaScript (jQuery) CAPTCHA as a first line of defense: http://docs.jquery.com/Tutorials:Safer_Contact_Forms_Without_CAPTCHAs The advantage of this approach is that, for most people, the CAPTCHA won't ever be visible! However, for people with JavaScript disabled, we still need a fallback and this is where it gets tricky. I have written a traditional CAPTCHA control for ASP.NET which we can re-use. However, I'd prefer to go with something textual to avoid the overhead of creating all these images on the server with each request. I've seen things like.. ASCII text captcha: \/\/(_)\/\/ math puzzles: what is 7 minus 3 times 2? trivia questions: what tastes better, a toad or a popsicle? Maybe I'm just tilting at windmills here, but I'd like to have a less resource intensive, non-image based <noscript> compatible CAPTCHA if possible. Ideas?

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  • java web templates across multiple WAR files

    - by Casey
    I have a multi WAR web application that was designed badly. There is a single WAR that is responsible for handling some authorization against a database and defines a standard web page using a jsp taglib. The main WAR basically checks the privileges of the user and than based on that, displays links to the context path of the other deployed WARS. Each of the other deployed WARs includes this custom tag lib. I am working on redesigning this application, and one of the nice things that I want to retain is that we have other project teams that have developed these WAR modules that "plug into" our current system to take advantage of other things we have to offer. I am not entirely sure how to handle the page templates though. I need a templating system that would be easy enough to use across multiple wars (I was thinking of jsp fragments??). I really only need to define a consistent header and main navigation section. Whatever else is displayed on the page is up to the individual web project. Any suggestions? I hope that this is clear, if not I can elaborate more.

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  • is it better to query database or grab from file? php & mysql

    - by pfunc
    I am keeping a large amount of words in a database that I want to match up articles to. I was thinking that it would just be better to keep these words in an array and grab that array whenever needed instead of querying the database every time (since the words won't be changing that much). Is there much performance difference in doing this? And if I were to do this, how to I write a script that writes the array to a a new php file. I tried writing the array like so: while( $row = mysql_fetch_assoc($query)) { $newArray[] = $row; } $fp = fopen('noWordsArr.php', 'w'); fwrite($fp, $newArray); fclose($fp); But all I get in the other file is "Array". So i figured I could write this and then write have a chron hit up the file every few days or so in case things have changed. But I guess if there is no performance advantage then it prob won't be necessary and I can just query the database every time I need to access the words.

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  • What is the difference between these two linq implementations?

    - by Mahesh Velaga
    I was going through Jon Skeet's Reimplemnting Linq to Objects series. In the implementation of where article, I found the following snippets, but I don't get what is the advantage that we are gettting by splitting the original method into two. Original Method: // Naive validation - broken! public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) { throw new ArgumentNullException("source"); } if (predicate == null) { throw new ArgumentNullException("predicate"); } foreach (TSource item in source) { if (predicate(item)) { yield return item; } } } Refactored Method: public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) { throw new ArgumentNullException("source"); } if (predicate == null) { throw new ArgumentNullException("predicate"); } return WhereImpl(source, predicate); } private static IEnumerable<TSource> WhereImpl<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { foreach (TSource item in source) { if (predicate(item)) { yield return item; } } } Jon says - Its for eager validation and then defferring for the rest of the part. But, I don't get it. Could some one please explain it in a little more detail, whats the difference between these 2 functions and why will the validations be performed in one and not in the other eagerly? Conclusion/Solution: I got confused due to my lack of understanding on which functions are determined to be iterator-generators. I assumed that, it is based on signature of a method like IEnumerable<T>. But, based on the answers, now I get it, a method is an iterator-generator if it uses yield statements.

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  • Can I create an application using SlimDX relying on the DirectX DLLs already bundled with Vista/Win7

    - by norheim.se
    I'm working on a .NET application that requires the use of accelerated graphics, currently DirectX 9.0c. The software is quite graphics intensive and must, in addition, be launchable from a CD or by ClickOnce without the user requiring administrator's permissions. I currently use SlimDX, which works great featurewise, but the users are getting rather annoyed by having to install the DirectX redistributable. Especially since this does require elevated permissions. It is rather hard to explain to them why the version of DirectX already bundled with their OS is not sufficient. After all - DirectX 9.0c has been around since 2004, and I'm not using any new fancy features. The ability to deliver an application that "just works" in Vista or Windows 7, without any particular additional prerequisites would be a huge advantage. Therefore: Is there any way I can build an application using DirectX 9.0c based on SlimDX, that relies only on the libraries provided in the standard Windows Vista/Win7 installation? That is - without requiring the additional DirectX redistributable to be installed? If not - is there any other managed (and preferably not abandoned) DirectX wrapper that can serve this purpose? Thanks in advance!

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  • Avoiding resource (localizable string) duplication with String.Format

    - by Hrvoje Prgeša
    I'm working on a application (.NET, but not relevant) where there is large potential for resource/string duplication - most of these strings are simple like: Volume: 33 Volume: 33 (dB) Volume 33 dB Volume (dB) Command - Volume: 33 (dB) where X, Y and unit are the same. Should I define a new resource for each of the string or is it preferable to use String.Format to simplify some of these, eg.: String.Format("{0}: {1}", Resource.Volume, 33) String.Format("{0}: {1} {2}", Resource.Volume, 33, Resource.dB) Resource.Volume String.Format("{0} ({1})", 33, Resource.dB) String.Format("{0} ({1})", Resource.Volume, Resource.dB) String.Format("Command - {0}: {1} {2}", Resource.Volume, 33, Resource.dB) I would also define string formats like "{0}: {1}" in the resources so there would be a possibility of reordering words... I would not use this approach selectivly and not throughout the whole application.. And how about: String.Format("{0}: {1}", Volume, Resource.Muted_Volume) // = Volume: Muted Resource.Muted_Volume String.Format("{0}: {1} (by user {2})", Volume, Resource.Muted_Volume, "xy") // = Volume: Muted (by user xy) The advantage is cutting the number of resource by the factor of 4-5. Are there any hidden dangers of using this approach? Could someone give me an example (language) where this would not work correctly?

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  • boost thread pool

    - by Dtag
    I need a threadpool for my application, and I'd like to rely on standard (C++11 or boost) stuff as much as possible. I realize there is an unofficial(!) boost thread pool class, which basically solves what I need, however I'd rather avoid it because it is not in the boost library itself -- why is it still not in the core library after so many years? In some posts on this page and elsewhere, people suggested using boost::asio to achieve a threadpool like behavior. At first sight, that looked like what I wanted to do, however I found out that all implementations I have seen have no means to join on the currently active tasks, which makes it useless for my application. To perform a join, they send stop signal to all the threads and subsequently join them. However, that completely nullifies the advantage of threadpools in my use case, because that makes new tasks require the creation of a new thread. What I want to do is: ThreadPool pool(4); for (...) { for (int i=0;i<something;i++) pool.pushTask(...); pool.join(); // do something with the results } Can anyone suggest a solution (except for using the existing unofficial thread pool on sourceforge)? Is there anything in C++11 or core boost that can help me here? Thanks a lot

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  • How expensive is a context switch? Is it better to implement a manual task switch than to rely on OS

    - by Vilx-
    The title says it all. Imagine I have two (three, four, whatever) tasks that have to run in parallel. Now, the easy way to do this would be to create separate threads and forget about it. But on a plain old single-core CPU that would mean a lot of context switching - and we all know that context switching is big, bad, slow, and generally simply Evil. It should be avoided, right? On that note, if I'm writing the software from ground up anyway, I could go the extra mile and implement my own task-switching. Split each task in parts, save the state inbetween, and then switch among them within a single thread. Or, if I detect that there are multiple CPU cores, I could just give each task to a separate thread and all would be well. The second solution does have the advantage of adapting to the number of available CPU cores, but will the manual task-switch really be faster than the one in the OS core? Especially if I'm trying to make the whole thing generic with a TaskManager and an ITask, etc?

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  • Best (functional?) programming language to learn coming from Mathematica

    - by Will Robertson
    As a mechanical engineering PhD student, I haven't had a great pedigree in programming as part of my “day job”. I started out in Matlab (having written some Hypercard and Applescript back in the day, and being introduced to Ada, of all things, in my 1st undergrad year), learned to program—if you can call it that—in (La)TeX; and finally discovered and fell for Mathematica. Now I'm interested in learning a "real" programming language that I can enjoy in the same sort of style as Mathematica, which tries to stress functional programming since it seems to map more nicely to how certain kinds of mathematics can be written algorithmically. So which functional language should I learn? I guess the obvious answer is “as many as possible”, but let's start out humble and give a single, well-considered option a good crack. I've heard good things about, say, Haskell and Scala, but I wonder if (given my non–computer science background) I'd be better off starting in more “grounded” territory and going with Ruby or Python (the latter having the big advantage of being used for Sage, which I'd also like to investigate…after my PhD). Well, I guess this is pretty subjective, so perhaps I could rephrase: would it be better to start looking at Haskell (say) straight after an ad-hoc education to functional programming in Mathematica, or will I get more out of learning Python (say) first? In reference to the question "what do I want to do with it?", I guess my answer is "fun, and learning more". I've got this list of languages that I'd like to look at, and I don't know how to trim them down. And I'd rather start with something a little higher-level than C simply so that I can be somewhat productive without having to re-invent many wheels for any code I'd like to write.

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  • How best to implement support for multiple devices in a web application.

    - by Kabeer
    Hello. My client would like a business application to support 'every possible device'. The application in question is essentially a web application and 'every possible device', I believe encompasses mobile phones, netbooks, ipad, other browser supporting devices, etc. The application is somewhat complex w.r.t. the data it captures and other functions it performs (reporting). If I continue to honor increasing complexity in the application, I guess there are more chances of it not working on other devices. I'd like to know how web applications support multiple devices conventionally? Are there multiple versions of presentation layer (like many times I find m.website.com dedicated for mobile devices)? Further, if my application is to take advantage of Java Script, RIA (Flash, SilverLight) then what are the consequences and workarounds? Mine is a .Net based application and the stack also contains Ext JS Java Script library. While I would like to use it for sure, considering that I would be doing a lot of work in Java Script rather than HTML, this could be a problem. The answer to the above could be descriptive. If there is something already prescribed out there, please share the link(s). Thanks.

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