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  • NoSQL for filesystem storage organization and replication?

    - by wheaties
    We've been discussing design of a data warehouse strategy within our group for meeting testing, reproducibility, and data syncing requirements. One of the suggested ideas is to adapt a NoSQL approach using an existing tool rather than try to re-implement a whole lot of the same on a file system. I don't know if a NoSQL approach is even the best approach to what we're trying to accomplish but perhaps if I describe what we need/want you all can help. Most of our files are large, 50+ Gig in size, held in a proprietary, third-party format. We need to be able to access each file by a name/date/source/time/artifact combination. Essentially a key-value pair style look-up. When we query for a file, we don't want to have to load all of it into memory. They're really too large and would swamp our server. We want to be able to somehow get a reference to the file and then use a proprietary, third-party API to ingest portions of it. We want to easily add, remove, and export files from storage. We'd like to set up automatic file replication between two servers (we can write a script for this.) That is, sync the contents of one server with another. We don't need a distributed system where it only appears as if we have one server. We'd like complete replication. We also have other smaller files that have a tree type relationship with the Big files. One file's content will point to the next and so on, and so on. It's not a "spoked wheel," it's a full blown tree. We'd prefer a Python, C or C++ API to work with a system like this but most of us are experienced with a variety of languages. We don't mind as long as it works, gets the job done, and saves us time. What you think? Is there something out there like this?

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  • Boost multi_index_container crash in release mode

    - by Zan Lynx
    I have a program that I just changed to using a boost::multi_index_container collection. After I did that and tested my code in debug mode, I was feeling pretty good about myself. However, then I compiled a release build with NDEBUG set, and the code crashed. Not immediately, but sometimes in single-threaded tests and often in multi-threaded tests. The segmentation faults happen deep inside boost insert and rotate functions related to the index updates and they are happening because a node has NULL left and right pointers. My code looks a bit like this: struct Implementation { typedef std::pair<uint32_t, uint32_t> update_pair_type; struct watch {}; struct update {}; typedef boost::multi_index_container< update_pair_type, boost::multi_index::indexed_by< boost::multi_index::ordered_unique< boost::multi_index::tag<watch>, boost::multi_index::member<update_pair_type, uint32_t, &update_pair_type::first> >, boost::multi_index::ordered_non_unique< boost::multi_index::tag<update>, boost::multi_index::member<update_pair_type, uint32_t, &update_pair_type::second> > > > update_map_type; typedef std::vector< update_pair_type > update_list_type; update_map_type update_map; update_map_type::iterator update_hint; void register_update(uint32_t watch, uint32_t update); void do_updates(uint32_t start, uint32_t end); }; void Implementation::register_update(uint32_t watch, uint32_t update) { update_pair_type new_pair( watch_offset, update_offset ); update_hint = update_map.insert(update_hint, new_pair); if( update_hint->second != update_offset ) { bool replaced _unused_ = update_map.replace(update_hint, new_pair); assert(replaced); } }

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  • getSharedPreferences not working for me with concerns to ListPreferences and Integers

    - by ideagent
    I'm stuck at a point where I'm trying to get my project to read a preference value (from a ListPreference listing) and then use that value in a basic mathematical subtraction instance. The problem is that the "seek" preference is not being seen by my Java code, and yet the default value is (I've tried the default value with 3000 and now 0). Am i missing something, is there a bug here, known or unknown? Java code chunk where the issues manifests itself: public static final String PREF_FILE_NAME = "preferences"; seekback.setOnClickListener(new Button.OnClickListener() { @Override public void onClick(View view) { try { SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE); Integer storedPreference = preferences.getInt("seek", 0); (mediaPlayer.getCurrentPosition()-storedPreference); } catch (Exception e) { e.printStackTrace(); } } }); Here are some other code bits for my project: From preferences file: <ListPreference android:entries="@array/seconds" android:entryValues="@array/seconds_values" android:summary="sets the seek interval for the seekback and seekforward buttons" android:title="Seek Interval" android:defaultValue="5000" android:key="@string/seek" From strings file: seek From an array file: Five seconds Fifteen seconds Thirty seconds Sixty seconds 5000 15000 30000 60000 let me know if you need to see more code to figure this one out Thanks in advance for any help that can be offered. I've worked over this issue now for a few hours and I'm burnt, a second pair of eyes on it would be very much appreciated. Arg, not sure how to get the code and plain text to format nicely here, even tried the options, like Code Sample, no luck AndroidCoder

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  • How to convert string with double high/wide characters to normal string [VC++6]

    - by Shaitan00
    My application typically recieves a string in the following format: " Item $5.69 " Some contants I always expect: - the LENGHT always 20 characters - the start index of the text always [5] - and most importantly the index of the DECIMAL for the price always [14] In order to identify this string correctly I validate all the expected contants listed above .... Some of my clients have now started sending the string with Doube-High / Double-Wide values (pair of characters which represent a single readable character) similar to the following: " Item $x80x90.x81x91x82x92 " For testing I simply scan the string character-by-character, compare char[i] and char[i+1] and replace these pairs with their corresponding single character when a match is found (works fine) as follows: [Code] for (int i=0; i < sData.length(); i++) { char ch = sData[i] & 0xFF; char ch2 = sData[i+1] & 0xFF; if (ch == '\x80' && ch2 == '\x90') zData.replace("\x80\x90", "0"); else if (ch == '\x81' && ch2 == '\x91') zData.replace("\x81\x91", "1"); else if (ch == '\x82' && ch2 == '\x92') zData.replace("\x82\x92", "2"); ... ... ... } [/Code] But the result is something like this: " Item $5.69 " Notice how this no longer matches my expectation: the lenght is now 17 (instead of 20) due to the 3 conversions and the decimal is now at index 13 (instead of 14) due to the conversion of the "5" before the decimal point. Ideally I would like to convert the string to a normal readable format keeping the constants (length, index of text, index of decimal) at the same place (so the rest of my application is re-usable) ... or any other suggestion (I'm pretty much stuck with this)... Is there a STANDARD way of dealing with these type of characters? Any help would be greatly appreciated, I've been stuck on this for a while now ... Thanks,

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  • PHP: MySQL query duplicating update for no reason

    - by ThinkingInBits
    The code below is first the client code, then the class file. For some reason the 'deductTokens()' method is calling twice, thus charging an account double. I've been programming all night, so I may just need a second pair of eyes: if ($action == 'place_order') { if ($_REQUEST['unlimited'] == 200) { $license = 'extended'; } else { $license = 'standard'; } if ($photograph->isValidPhotographSize($photograph_id, $_REQUEST['size_radio'])) { $token_cost = $photograph->getTokenCost($_REQUEST['size_radio'], $_REQUEST['unlimited']); $order = new ImageOrder($_SESSION['user']['id'], $_REQUEST['size_radio'], $license, $token_cost); $order->saveOrder(); $order->deductTokens(); header('location: account.php'); } else { die("Please go back and select a valid photograph size"); } } ######CLASS CODE####### <?php include_once('database_classes.php'); class Order { protected $account_id; protected $cost; protected $license; public function __construct($account_id, $license, $cost) { $this->account_id = $account_id; $this->cost = $cost; $this->license = $license; } } class ImageOrder extends Order { protected $size; public function __construct($account_id, $size, $license, $cost) { $this->size = $size; parent::__construct($account_id, $license, $cost); } public function saveOrder() { //$db = Connect::connect(); //$account_id = $db->real_escape_string($this->account_id); //$size = $db->real_escape_string($this->size); //$license = $db->real_escape_string($this->license); //$cost = $db->real_escape_string($this->cost); } public function deductTokens() { $db = Connect::connect(); $account_id = $db->real_escape_string($this->account_id); $cost = $db->real_escape_string($this->cost); $query = "UPDATE accounts set tokens=tokens-$cost WHERE id=$account_id"; $result = $db->query($query); } } ?> When I die("$query"); directly after the query, it's printing the proper statement, and when I run that query within MySQL it works perfectly.

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  • How to avoid the following purify detected memory leak in C++?

    - by Abhijeet
    Hi, I am getting the following memory leak.Its being probably caused by std::string. how can i avoid it? PLK: 23 bytes potentially leaked at 0xeb68278 * Suppressed in /vobs/ubtssw_brrm/test/testcases/.purify [line 3] * This memory was allocated from: malloc [/vobs/ubtssw_brrm/test/test_build/linux-x86/rtlib.o] operator new(unsigned) [/vobs/MontaVista/Linux/montavista/pro/devkit/x86/586/target/usr/lib/libstdc++.so.6] operator new(unsigned) [/vobs/ubtssw_brrm/test/test_build/linux-x86/rtlib.o] std::string<char, std::char_traits<char>, std::allocator<char>>::_Rep::_S_create(unsigned, unsigned, std::allocator<char> const&) [/vobs/MontaVista/Linux/montavista/pro/devkit/ x86/586/target/usr/lib/libstdc++.so.6] std::string<char, std::char_traits<char>, std::allocator<char>>::_Rep::_M_clone(std::allocator<char> const&, unsigned) [/vobs/MontaVista/Linux/montavista/pro/devkit/x86/586/tar get/usr/lib/libstdc++.so.6] std::string<char, std::char_traits<char>, std::allocator<char>>::string<char, std::char_traits<char>, std::allocator<char>>(std::string<char, std::char_traits<char>, std::alloc ator<char>> const&) [/vobs/MontaVista/Linux/montavista/pro/devkit/x86/586/target/usr/lib/libstdc++.so.6] uec_UEDir::getEntryToUpdateAfterInsertion(rcapi_ImsiGsmMap const&, rcapi_ImsiGsmMap&, std::_Rb_tree_iterator<std::pair<std::string<char, std::char_traits<char>, std::allocator< char>> const, UEDirData >>&) [/vobs/ubtssw_brrm/uectrl/linux-x86/../src/uec_UEDir.cc:2278] uec_UEDir::addUpdate(rcapi_ImsiGsmMap const&, LocalUEDirInfo&, rcapi_ImsiGsmMap&, int, unsigned char) [/vobs/ubtssw_brrm/uectrl/linux-x86/../src/uec_UEDir.cc:282] ucx_UEDirHandler::addUpdateUEDir(rcapi_ImsiGsmMap, UEDirUpdateType, acap_PresenceEvent) [/vobs/ubtssw_brrm/ucx/linux-x86/../src/ucx_UEDirHandler.cc:374]

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  • 2 iframes with the same display even if the src are different

    - by JulienH
    Hi, I am using this code: <div class="infobox-pair"> <div class="ibp-left"> <iframe width="105" height="350" frameborder="0" scrolling="no" style="width: 311px; height: 105px;" marginwidth="0" marginheight="0" name="infobox_flight" id="ibp-left-iframe" src="http://mywebpage.com/paris"></iframe> </div> <div class="ibp-right"> <iframe width="105" height="350" frameborder="0" scrolling="no" style="width: 311px; height: 105px;" marginwidth="0" marginheight="0" name="infobox_package" id="ibp-right-iframe" src="http://mywebpage.com/lisbonne"></iframe> </div> That is displaying into the same div two different iframes. When I display the page whatever the browser it happens that I can get the same content for both the iframes even if looking at the source code the iframe are still different (based on their src and id). It doesn't happen 100% of the time, I have to refresh sometimes several times to see it. Do you have any clue ? Thanks in advance

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  • What if a large number of objects are passed to my SwingWorker.process() method?

    - by Trejkaz
    I just found an interesting situation. Suppose you have some SwingWorker (I've made this one vaguely reminiscent of my own): public class AddressTreeBuildingWorker extends SwingWorker<Void, NodePair> { private DefaultTreeModel model; public AddressTreeBuildingWorker(DefaultTreeModel model) { } @Override protected Void doInBackground() { // Omitted; performs variable processing to build a tree of address nodes. } @Override protected void process(List<NodePair> chunks) { for (NodePair pair : chunks) { // Actually the real thing inserts in order. model.insertNodeInto(parent, child, parent.getChildCount()); } } private static class NodePair { private final DefaultMutableTreeNode parent; private final DefaultMutableTreeNode child; private NodePair(DefaultMutableTreeNode parent, DefaultMutableTreeNode child) { this.parent = parent; this.child = child; } } } If the work done in the background is significant then things work well - process() is called with relatively small lists of objects and everything is happy. Problem is, if the work done in the background is suddenly insignificant for whatever reason, process() receives a huge list of objects (I have seen 1,000,000, for instance) and by the time you process each object, you have spent 20 seconds on the Event Dispatch Thread, exactly what SwingWorker was designed to avoid. In case it isn't clear, both of these occur on the same SwingWorker class for me - it depends on the input data, and the type of processing the caller wanted. Is there a proper way to handle this? Obviously I can intentionally delay or yield the background processing thread so that a smaller number might arrive each time, but this doesn't feel like the right solution to me.

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  • Read Cookies using Javascript

    - by Ajith
    I want to create a cookie using php,an also i need to read it using javascript.ie, by using setcookie('mycookie','hello',time()+34000) in php i am creating a cookie in my system.Now,i need to read it using javascript.Is it possible?If anybody knows please give me some idea.Please....help me.I am using javscript as follows ` function Get_Cookie( check_name ) { // first we'll split this cookie up into name/value pairs // note: document.cookie only returns name=value, not the other components var a_all_cookies = document.cookie.split( ';' ); var a_temp_cookie = ''; var cookie_name = ''; var cookie_value = ''; var b_cookie_found = false; // set boolean t/f default f for ( i = 0; i < a_all_cookies.length; i++ ) { // now we'll split apart each name=value pair a_temp_cookie = a_all_cookies[i].split( '=' ); // and trim left/right whitespace while we're at it cookie_name = a_temp_cookie[0].replace(/^\s+|\s+$/g, ''); // if the extracted name matches passed check_name if ( cookie_name == check_name ) { b_cookie_found = true; // we need to handle case where cookie has no value but exists (no = sign, that is): if ( a_temp_cookie.length > 1 ) { cookie_value = unescape( a_temp_cookie[1].replace(/^\s+|\s+$/g, '') ); } // note that in cases where cookie is initialized but no value, null is returned return cookie_value; break; } a_temp_cookie = null; cookie_name = ''; } if ( !b_cookie_found ) { return null; } } if (Get_Cookie('__gsb')) { alert('Found'); } `

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  • How to check whether user is login in web application?

    - by Morgan Cheng
    I want to learn the whole details of web application authentication. So, I decided to write a CodeIgniter authentication library from scratch. Now, I have to make design decision about how to determine whether one user is login. Basically, after user input username & password pair. A cookie is set for this session, following navigations in the web application will not require username & password. The server side will check whether the session cookie is valid to determine whether current user is login. The question is: how to determine whether cookie is valid cookie issued from server side? I can image the most simple way is to have the cookie value stored in session status as well. For each HTTP request, compare the value from cookie and the value from server session. (Since CodeIgniter session library store session variables in cookies, it is not applicable without some tweak.) This method requires storage in server side. For huge web application that is deployed in multiple datacenters. It is possible that user input username & password when browsing in one datacenter, while he/she access the web application in another datacenter later. The expected behavior is that user just input username & password once. As a result, all datacenters should be able to access the session status. That is possible not applicable even the session status is stored in external storage such as database. I tried Google. I login Google with Asian proxy which is supposed to direct me to datacenters in Asian. Then I switch to North American proxy which should direct me to datacenters in North America. It recognize my login without asking username and password again. So, is there any way to determine whether user is login without server side session status?

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  • Installing Mercurial on Windows Apache XAMPP Tutorial

    - by Tim Dellas
    After asking this question (http://stackoverflow.com/questions/2675764/xampp-mercurial-installation-on-windows-apache-hgwebdir-cgi-script-error) and reading though the whole internet including this question (http://stackoverflow.com/questions/644322/how-do-i-get-mercurials-hgwebdir-working-on-windows) and all its links for about 10 hours, I seem to not be able to find a solution. I begun with this tutorial http://mercurial.selenic.com/wiki/HgWebDirStepByStep ... and I really don't want to install ancient versions of Mercurial. I got my windows-apache to run Python scripts, CGI-Scripts, publish them in the wild, but hgwebdir just won't work. Question 1: Can someone please enrich his personal blog with a tutorial on how to install MERCURIAL on a WINDOWS XAMPP installation and make it visible to the world? I guarantee a lot of pageviews, as this is not a trivial problem. And this would sincerely help a lot of other people I guess. Question 2: For example, even after browsing half a day through everywhere, I just cannot find out, which version of python I need to pair with the freshest version of mercurial, and I get the "magic number is wrong"-error. This would be my question, if noone has time to make up a nice blogpost. Sorry for being a bit frustrated.

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  • Design an Application That Stores and Processes Files

    - by phasetwenty
    I'm tasked with writing an application that acts as a central storage point for files (usually document formats) as provided by other applications. It also needs to take commands like "file 395 needs a copy in X format", at which point some work is offloaded to a 3rd party application. I'm having trouble coming up with a strategy for this. I'd like to keep the design as simple as possible, so I'd like to avoid big extra frameworks or techniques like threads for as long as it makes sense. The clients are expected to be web applications (for example, one is a django application that receives files from our customers; the others are not yet implemented). The platform it will be running on is likely going to be Python on Linux, unless I have a strong argument to use something else. In the beginning I thought I could fit the information I wanted to communicate in the filenames, and let my application parse the filename to figure out what it needed to do, but this is proving too inflexible with the amount of information I'm realizing I need to make available. Another idea is to pair FTP with a database used as a communication medium (client uploads a file and updates the database with a command as a row in a table) but I don't like this idea because adding commands (a known change) looks like it will require adding code as well as changing database schemas. It will also muddy up the interface my clients will have to use. I looked into Pyro to let applications communicate more directly but I don't like the idea of running an extra nameserver for this one purpose. I also don't see a good way to do file transfer within this framework. What I'm looking for is techniques and/or technologies applicable to my problem. At the simplest level, I need the ability to accept files and messages with them.

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  • Optimization in Common Decalaration

    - by Pratik
    Its a 3-tier ASP.NET Website Project In Data Layer there is class "Common Decalaration" in which lot of common things are mentioned. Something this way : public class CommonDeclartion { #region Common Messages public const string RECORD_INSERT_MSG = "Record Inserted Successfully "; public const string RECORD_UPDATE_MSG = "Record Updated Successfully"; public const string RECORD_DELETE_MSG = "Record Deleted Successfully"; public const string ERROR_MSG = "Error Ocuured while Perfoming This Action."; public const string UserID_Incorrect = "Please Enter The Correct User ID."; public const string RECORD_ALREADY_EXIT = "Record Already Exit"; public const string NO_RECORD = "No Record found."; #endregion } Can this be more optimized in terms of : 1.Perfomance 2.Security(if any) 3.Code Readablity or Reusablity I thought of using enum but can't figure that out : enum CommonMessages { RECORD_INSERT_MSG "Record Inserted Successfully.", RECORD_UPDATE_MSG "Record Updated Successfully.", RECORD_DELETE_MSG "Record Deleted Successfully.", ERROR_MSG "Error Ocuured while Perfoming This Action.", UserID_Incorrect "Please Enter The Correct User ID.", RECORD_ALREADY_EXIT "Record Already Exit.", NO_RECORD "No Record found.", } or else should keep them in some collections like dictionary/NameValueCollection or so or i have to keep them in XML in form of key/value pair and reterive from it ? What can be better way keeping in mind 1.Perfomance 2.Security(if any) 3.Code Readablity or Reusablity

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  • Strange Effect with Overridden Properties and Reflection

    - by naacal
    I've come across a strange behaviour in .NET/Reflection and cannot find any solution/explanation for this: Class A { public string TestString { get; set; } } Class B : A { public override string TestString { get { return "x"; } } } Since properties are just pairs of functions (get_PropName(), set_PropName()) overriding only the "get" part should leave the "set" part as it is in the base class. And this is just what happens if you try to instanciate class B and assign a value to TestString, it uses the implementation of class A. But what happens if I look at the instantiated object of class B in reflection is this: PropertyInfo propInfo = b.GetType().GetProperty("TestString"); propInfo.CanRead ---> true propInfo.CanWrite ---> false(!) And if I try to invoke the setter from reflection with: propInfo.SetValue("test", b, null); I'll even get an ArgumentException with the following message: Property set method not found. Is this as expected? Because I don't seem to find a combination of BindingFlags for the GetProperty() method that returns me the property with a working get/set pair from reflection.

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  • CSS - vertical align text where text can be multiple lines

    - by Sniffer
    Hi all I've been given a design by a graphic designer, which I'm trying to put into HTML and CSS. One of the issues I'm facing is on a user input form. In the design the labels for each input are a fixed width - say 100px. The container for each label/input pair is fixed at 2em. The design I've been given has asked that the text for each label is vertically aligned. So the structure is like this: <containerTag> <label /> <input /> </containerTag> No problems as long as the text is on one line (I would have just used line-height of 2em to match the container), but some of the text in the labels are wrapping to two or even lines. Is there a semantic and nice way to get around this problem? I need something that will work in IE6-9, Firefox 3.5+, Chrome and Safari. Although I am using progressive enhancement, so if there is a solution that will only work on the later browsers, but won't break the older ones, then this would be acceptable. Any help gratefully received! Thanks for your time S

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  • Uniquing with Existing Core Data Entities

    - by warrenm
    I'm using Core Data to store a lot (1000s) of items. A pair of properties on each item are used to determine uniqueness, so when a new item comes in, I compare it against the existing items before inserting it. Since the incoming data is in the form of an RSS feed, there are often many duplicates, and the cost of the uniquing step is O(N^2), which has become significant. Right now, I create a set of existing items before iterating over the list of (possible) new items. My theory is that on the first iteration, all the items will be faulted in, and assuming we aren't pressed for memory, most of those items will remain resident over the course of the iteration. I see my options thusly: Use string comparison for uniquing, iterating over all "new" items and comparing to all existing items (Current approach) Use a predicate to filter the set of existing items against the properties of the "new" items. Use a predicate with Core Data to determine uniqueness of each "new" item (without retrieving the set of existing items). Is option 3 likely to be faster than my current approach? Do you know of a better way?

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  • Recursive templates: compilation error under g++

    - by Johannes
    Hi, I am trying to use templates recursively to define (at compile-time) a d-tuple of doubles. The code below compiles fine with Visual Studio 2010, but g++ fails and complains that it "cannot call constructor 'point<1::point' directly". Could anyone please shed some light on what is going on here? Many thanks, Jo #include <iostream> #include <utility> using namespace std; template <const int N> class point { private: pair<double, point<N-1> > coordPointPair; public: point() { coordPointPair.first = 0; coordPointPair.second.point<N-1>::point(); } }; template<> class point<1> { private: double coord; public: point() { coord= 0; } }; int main() { point<5> myPoint; return 0; }

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  • Cross-platform iteration of Unicode string

    - by kizzx2
    I want to iterate each character of a Unicode string, treating each surrogate pair and combining character sequence as a single unit (one grapheme). Example The text "??????" is comprised of the code points: U+0928, U+092E, U+0938, U+094D, U+0924, U+0947, of which, U+0938 and U+0947 are combining marks. static void Main(string[] args) { const string s = "??????"; Console.WriteLine(s.Length); // Ouptuts "6" var l = 0; var e = System.Globalization.StringInfo.GetTextElementEnumerator(s); while(e.MoveNext()) l++; Console.WriteLine(l); // Outputs "4" } So there we have it in .NET. We also have Win32's CharNextW() #include <Windows.h> #include <iostream> #include <string> int main() { const wchar_t * s = L"??????"; std::cout << std::wstring(s).length() << std::endl; // Gives "6" int l = 0; while(CharNextW(s) != s) { s = CharNextW(s); ++l; } std::cout << l << std::endl; // Gives "4" return 0; } Question Both ways I know of are specific to Microsoft. Are there portable ways to do it? I heard about ICU but I couldn't find something related quickly (UnicodeString(s).length() still gives 6). Would be an acceptable answer to point to the related function/module in ICU. C++ doesn't have a notion of Unicode, so a lightweight cross-platform library for dealing with these issues would make an acceptable answer.

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  • How to exclude rows where matching join is in an SQL tree

    - by Greg K
    Sorry for the poor title, I couldn't think how to concisely describe this problem. I have a set of items that should have a 1-to-1 relationship with an attribute. I have a query to return those rows where the data is wrong and this relationship has been broken (1-to-many). I'm gathering these rows to fix them and restore this 1-to-1 relationship. This is a theoretical simplification of my actual problem but I'll post example table schema here as it was requested. item table: +------------+------------+-----------+ | item_id | name | attr_id | +------------+------------+-----------+ | 1 | BMW 320d | 20 | | 1 | BMW 320d | 21 | | 2 | BMW 335i | 23 | | 2 | BMW 335i | 34 | +------------+------------+-----------+ attribute table: +---------+-----------------+------------+ | attr_id | value | parent_id | +---------+-----------------+------------+ | 20 | SE | 21 | | 21 | M Sport | 0 | | 23 | AC | 24 | | 24 | Climate control | 0 | .... | 34 | Leather seats | 0 | +---------+-----------------+------------+ A simple query to return items with more than one attribute. SELECT item_id, COUNT(DISTINCT(attr_id)) AS attributes FROM item GROUP BY item_id HAVING attributes > 1 This gets me a result set like so: +-----------+------------+ | item_id | attributes | +-----------+------------+ | 1 | 2 | | 2 | 2 | | 3 | 2 | -- etc. -- However, there's an exception. The attribute table can hold a tree structure, via parent links in the table. For certain rows, parent_id can hold the ID of another attribute. There's only one level to this tree. Example: +---------+-----------------+------------+ | attr_id | value | parent_id | +---------+-----------------+------------+ | 20 | SE | 21 | | 21 | M Sport | 0 | .... I do not want to retrieve items in my original query where, for a pair of associated attributes, they related like attributes 20 & 21. I do want to retrieve items where: the attributes have no parent for two or more attributes they are not related (e.g. attributes 23 & 34) Example result desired, just the item ID: +------------+ | item_id | +------------+ | 2 | +------------+ How can I join against attributes from items and exclude these rows? Do I use a temporary table or can I achieve this from a single query? Thanks.

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  • Hibernate: fetching multiple bags efficiently

    - by Jens Jansson
    Hi! I'm developing a multilingual application. For this reason many objects have in their name and description fields collections of something I call LocalizedStrings instead of plain strings. Every LocalizedString is basically a pair of a locale and a string localized to that locale. Let's take an example an entity, let's say a book -object. public class Book{ @OneToMany private List<LocalizedString> names; @OneToMany private List<LocalizedString> description; //and so on... } When a user asks for a list of books, it does a query to get all the books, fetches the name and description of every book in the locale the user has selected to run the app in, and displays it back to the user. This works but it is a major performance issue. For the moment hibernate makes one query to fetch all the books, and after that it goes through every single object and asks hibernate for the localized strings for that specific object, resulting in a "n+1 select problem". Fetching a list of 50 entities produces about 6000 rows of sql commands in my server log. I tried making the collections eager but that lead me to the "cannot simultaneously fetch multiple bags"-issue. Then I tried setting the fetch strategy on the collections to subselect, hoping that it would do one query for all books, and after that do one query that fetches all LocalizedStrings for all the books. Subselects didn't work in this case how i would have hoped and it basically just did exactly the same as my first case. I'm starting to run out of ideas on how to optimize this. So in short, what fetching strategy alternatives are there when you are fetching a collection and every element in that collection has one or multiple collections in itself, which has to be fetch simultaneously.

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  • jQuery Syntax Error - Trying to detect viewport size and select background image to use w/CSS

    - by CuppyCakes
    Hi all. Please be gentle, I'm still learning. I imagine that the solution to my problem is simple and that perhaps I have just been in front of the computer too long. I am trying to detect the size of the viewport, and then use a different sized image for a background on an element depending on the size of the viewport. Here is what I have so far: $(document).ready(function(){ var pageWidth = $(window).width(); if ( pageWidth <= 1280 ) { $('#contact').css('background-image', 'url(../images/contact_us_low.jpg)'); } elseif ( pageWidth > 1280 ) { $('#contact').css('background-image', 'url(../images/contact_us_high.jpg)'); } }); Error: missing ; before statement [Break on this error] elseif ( pageWidth 1280 ) {\n (Line 7) To me it seems like all of my semi-colons are in the right place. Two questions: Am I going about solving the problem in a sensible way? To me a simple conditional should solve this background problem, as the code is merely selecting between two images based on what size it detects the viewport to be. Can you please help point out my n00b syntax error? Sometimes it really does help to have an extra pair of eyes look at something like this, even if small. Thank you kindly for your advice, I will continue poking and perusing the docs I have available to me.

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  • How to write a custom predicate for multi_index_containder with composite_key?

    - by Titan
    I googled and searched in the boost's man, but didn't find any examples. May be it's a stupid question...anyway. So we have the famous phonebook from the man: typedef multi_index_container< phonebook_entry, indexed_by< ordered_non_unique< composite_key< phonebook_entry, member<phonebook_entry,std::string,&phonebook_entry::family_name>, member<phonebook_entry,std::string,&phonebook_entry::given_name> >, composite_key_compare< std::less<std::string>, // family names sorted as by default std::greater<std::string> // given names reversed > >, ordered_unique< member<phonebook_entry,std::string,&phonebook_entry::phone_number> > > > phonebook; phonebook pb; ... // look for all Whites std::pair<phonebook::iterator,phonebook::iterator> p= pb.equal_range(boost::make_tuple("White"), my_custom_comp()); How should my_custom_comp() look like? I mean it's clear for me then it takes boost::multi_index::composite_key_result<CompositeKey> as an argumen (due to compilation errors :) ), but what is CompositeKey in that particular case? struct my_custom_comp { bool operator()( ?? boost::multi_index::composite_key_result<CompositeKey> ?? ) const { return blah_blah_blah; } }; Thanks in advance.

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  • When to define SDD operations System->Actor?

    - by devoured elysium
    I am having some trouble understanding how to make SDDs, as I don't fully grasp why in some cases one should define operations for System - Actor and in others don't. Here is an example: 1) The User tells the System that wants to buy some tickets, stating his client number. 2) The System confirms that the given client number is valid. 3) The User tells the System the movie that wants to see. 4) The System shows the set of available sessions and seats for that movie. 5) The System asks the user which session/seat he wants. 6) The user tells the System the chosen session/seat. This would be converted to: a) -----> tellClientNumber(clientNumber) b) <----- validClientNumber c) -----> tellMovieToSee(movie) d) <----- showsAvailableSeatsHours e) -----> tellSystemChosenSessionSeat(session, seat) I know that when we are dealing with SDD's we are still far away from coding. But I can't help trying to imagine how it how it would have been had I to convert it right away to code: I can understand 1) and 2). It's like if it was a C#/Java method with the following signature: boolean tellClientNumber(clientNumber) so I put both on the SDD. Then, we have the pair 3) 4). I can imagine that as something as: SomeDataStructureThatHoldsAvailableSessionsSeats tellSystemMovieToSee(movie) Now, the problem: From what I've come to understand, my lecturer says that we shouldn't make an operation on the SDD for 5) as we should only show operations from the Actor to the System and when the System is either presenting us data (as in c)) or validating sent data (such as in b)). I find this odd, as if I try to imagine this like a DOS app where you have to put your input sequencially, it makes sense to make an arrow even for 5). Why is this wrong? How should I try to visualize this? Thanks

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  • What's the correct way to pass parameters from VBScript to COM interface implemented in C#?

    - by nopopem
    I'm trying to expose a fairly simple C# class to COM which should be usable from VBScript (among others). Some objects need to be created via COM calls and will be used in furter calls later on. The definition of the exposed classes and interfaces looks like this: namespace Test { [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)] public interface IComInterface { IFoo CreateFoo(); void UseFoo(int x, IFoo f); } [ClassInterface(ClassInterfaceType.None)] public sealed class CComInterface : IComInterface { public CComInterface() {} public IFoo CreateFoo() { return new Foo(); } public void UseFoo(int x, IFoo f) { f.Bar(); } } [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)] public interface IFoo { void Bar(); } [ClassInterface(ClassInterfaceType.None)] public class Foo : IFoo { internal Foo() {} public void Bar() {} } } The simplest thinkable COM client in VBScript does this: Dim ci Set ci = WScript.CreateObject("Test.CComInterface") Dim foo Set foo = ci.CreateFoo foo.Bar ci.UseFoo 0, foo While the call to Bar succeeds, calling UseFoo fails with "Error 5: invalid procedure call or invalid argument" The generated IDL seems ok to me: dispinterface IComInterface { properties: methods: [id(0x60020003)] IFoo* CreateFoo(); [id(0x60020004)] void UseFoo( [in] long x, [in] IFoo* f); }; The vbs call succeeds when I wrap the second parameter in parentheses like this: ci.UseFoo 0, (foo) As far as I understand (I'm no VBScript expert however) this forces the reference to foo to be passed by value, i.e. a copy of the reference is being made. How can I change the interface so that it can be called with the foo reference directly? Since this will be a public interface used by customers I don't like the idea of having to explain why all the objects created need to be passed back in an extra pair of parentheses...

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  • Using an initializer_list on a map of vectors

    - by Hooked
    I've been trying to initialize a map of <ints, vector<ints> > using the new 0X standard, but I cannot seem to get the syntax correct. I'd like to make a map with a single entry with key:value = 1:<3,4 #include <initializer_list> #include <map> #include <vector> using namespace std; map<int, vector<int> > A = {1,{3,4}}; .... It dies with the following error using gcc 4.4.3: error: no matching function for call to std::map<int,std::vector<int,std::allocator<int> >,std::less<int>,std::allocator<std::pair<const int,std::vector<int,std::allocator<int> > > > >::map(<brace-enclosed initializer list>) Edit Following the suggestion by Cogwheel and adding the extra brace it now compiles with a warning that can be gotten rid of using the -fno-deduce-init-list flag. Is there any danger in doing so?

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