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  • How to search cvs comment history

    - by Chris Noe
    I am aware of this command: cvs log -N -w<userid> -d"1 day ago" Unfortunately this generates a formatted report with lots of newlines in it, such that the file-path, the file-version, and the comment-text are all on separate lines. Therefore it is difficult to scan it for all occurrences of comment text, (eg, grep), and correlate the matches to file/version. (Note that the log output would be perfectly acceptable, if only cvs could perform the filtering natively.) EDIT: Sample output. A block of text like this is reported for each repository file: RCS file: /data/cvs/dps/build.xml,v Working file: build.xml head: 1.49 branch: locks: strict access list: keyword substitution: kv total revisions: 57; selected revisions: 1 description: ---------------------------- revision 1.48 date: 2008/07/09 17:17:32; author: noec; state: Exp; lines: +2 -2 Fixed src.jar references ---------------------------- revision 1.47 date: 2008/07/03 13:13:14; author: noec; state: Exp; lines: +1 -1 Fixed common-src.jar reference. =============================================================================

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  • Null Safe dereferencing in Java like ?. in Groovy using Maybe monad

    - by Sathish
    I'm working on a codebase ported from Objective C to Java. There are several usages of method chaining without nullchecks dog.collar().tag().name() I was looking for something similar to safe-dereferencing operator ?. in Groovy instead of having nullchecks dog.collar?.tag?.name This led to Maybe monad to have the notion of Nothing instead of Null. But all the implementations of Nothing i came across throw exception when value is accessed which still doesn't solve the chaining problem. I made Nothing return a mock, which behaves like NullObject pattern. But it solves the chaining problem. Is there anything wrong with this implementation of Nothing? [http://github.com/sathish316/jsafederef/blob/master/src/s2k/util/safederef/Nothing.java] As far as i can see 1. It feels odd to use mocking library in code 2. It doesn't stop at the first null. 3. How do i distinguish between null result because of null reference or name actually being null? How is it distinguished in Groovy code?

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  • How to get the Video-ID of a just uploaded Youtube movie

    - by murze
    Hi, how can i get the video-id of a just uploaded Youtube movie? I'm using this code: $yt = new Zend_Gdata_YouTube($httpClient); // create a new Zend_Gdata_YouTube_VideoEntry object $myVideoEntry = new Zend_Gdata_YouTube_VideoEntry(); // create a new Zend_Gdata_App_MediaFileSource object $filesource = $yt->newMediaFileSource('mytestmovie.mov'); $filesource->setContentType('video/quicktime'); // set slug header $filesource->setSlug('mytestmovie.mov'); // add the filesource to the video entry $myVideoEntry->setMediaSource($filesource); $myVideoEntry->setVideoTitle('My Test Movie'); $myVideoEntry->setVideoDescription('My Test Movie'); $myVideoEntry->setVideoCategory('Comedy'); // Note that category must be a valid YouTube category ! // set keywords, please note that this must be a comma separated string // and that each keyword cannot contain whitespace $myVideoEntry->setVideoTags('cars, funny'); // upload URI for the currently authenticated user $uploadUrl = 'http://uploads.gdata.youtube.com/feeds/api/users/default/uploads'; // try to upload the video, catching a Zend_Gdata_App_HttpException if available // or just a regular Zend_Gdata_App_Exception try { $newEntry = $yt->insertEntry($myVideoEntry, $uploadUrl, 'Zend_Gdata_YouTube_VideoEntry'); } catch (Zend_Gdata_App_HttpException $httpException) { echo $httpException->getRawResponseBody(); } catch (Zend_Gdata_App_Exception $e) { echo $e->getMessage(); } I assume it 'll be a property of $newEntry but i can't seem to find it! Thanks!

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  • Reading a Wordpress function description

    - by Casebash
    I want to be able to understand the standard function description that is provided for Wordpress functions. In particular, could someone explain the following example from here: Usage <?php wp_list_categories( $args ); ?> Default Usage <?php $args = array( 'show_option_all' => , 'orderby' => 'name', 'order' => 'ASC', 'show_last_update' => 0, 'style' => 'list', 'show_count' => 0, 'hide_empty' => 1, 'use_desc_for_title' => 1, 'child_of' => 0, 'feed' => , 'feed_type' => , 'feed_image' => , 'exclude' => , 'exclude_tree' => , 'include' => , 'current_category' => 0, 'hierarchical' => true, 'title_li' => __( 'Categories' ), 'number' => NULL, 'echo' => 1, 'depth' => 0 ); ?> I can guess most of it, but in particular I can't guess: What does blank after the comma mean? Empty string? What is the __? How do I call the function? Keyword like python, positional arguments or do I have to pass an array? Is there anything else about Wordpress function descriptions which isn't covered in this example? Thanks, Chris

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  • Is extending a base class with non-virtual destructor dangerous in C++

    - by Akusete
    Take the following code class A { }; class B : public A { }; class C : public A { int x; }; int main (int argc, char** argv) { A* b = new B(); A* c = new C(); //in both cases, only ~A() is called, not ~B() or ~C() delete b; //is this ok? delete c; //does this line leak memory? return 0; } when calling delete on a class with a non-virtual destructor with member functions (like class C), can the memory allocator tell what the proper size of the object is? If not, is memory leaked? Secondly, if the class has no member functions, and no explicit destructor behaviour (like class B), is everything ok? I ask this because I wanted to create a class to extend std::string, (which I know is not recommended, but for the sake of the discussion just bear with it), and overload the +=,+ operator. -Weffc++ gives me a warning because std::string has a non virtual destructor, but does it matter if the sub-class has no members and does not need to do anything in its destructor? -- FYI the += overload was to do proper file path formatting, so the path class could be used like class path : public std::string { //... overload, +=, + //... add last_path_component, remove_path_component, ext, etc... }; path foo = "/some/file/path"; foo = foo + "filename.txt"; //and so on... I just wanted to make sure someone doing this path* foo = new path(); std::string* bar = foo; delete bar; would not cause any problems with memory allocation

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  • C++ Beginner Delete Question

    - by Pooch
    Hi all, This is my first year learning C++ so bear with me. I am attempting to dynamically allocate memory to the heap and then delete the allocated memory. Below is the code that is giving me a hard time: // String.cpp #include "String.h" String::String() {} String::String(char* source) { this->Size = this->GetSize(source); this->CharArray = new char[this->Size + 1]; int i = 0; for (; i < this->Size; i++) this->CharArray[i] = source[i]; this->CharArray[i] = '\0'; } int String::GetSize(const char * source) { int i = 0; for (; source[i] != '\0'; i++); return i; } String::~String() { delete[] this->CharArray; } Here is the error I get when the compiler tries to delete the CharArray: 0xC0000005: Access violation reading location 0xccccccc0. And here is the last call on the stack: msvcr100d.dll!operator delete(void * pUserData) Line 52 + 0x3 bytes C++ I am fairly certain the error exists within this piece of code but will provide you with any other information needed. Oh yeah, using VS 2010 for XP. Thanks for any and all help!

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  • emacs public/protected/private label indentation of C++ header file not working for zero offset

    - by murrekatt
    I cannot get zero offset for some things for my C++ header files in emacs even if I have it defined in my .emacs file. The header file below shows a class definition inside two namespaces and most importantly the public keyword I would like to have with zero offset like below. namespace n1 { namespace n2 { class SomeClass { public: // this line with zero offset SomeClass(); ... }; } // n2 } // n2 In my .emacs file I have added label like this: (c-set-offset 'label 0) I used Ctrl-C Ctrl-S to find out what to modify. Other offsets I have defined in the .emacs file are working fine and also values other than 0 work for label. When I set offset 0 for label it turns out to be 1 when hitting tab for that line. This is strange and looks like something else is overriding or adding a minimum of 1. Can anyone explain how I can achieve what I want and maybe also an explanation what is happening currently? Phew, this was my first question here. Thanks :)

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  • pdfmark for docinfo metadata in pdf is not accepting accented characters in Keywords or Subject

    - by rpilkey
    I am inserting metadata into postscript files with a program, to be distilled to pdf with Adobe Distiller. I am using this code that I grabbed from Thomas Merz's "Web Publishing with Acrobat-PDF": /pdfmark where {pop} {userdict /pdfmark /cleartomark load put} ifelse [ /Title (mot accenté) /Author (mot accenté) /Subject (mot accenté) /Keywords (mot accenté) /DOCINFO pdfmark When you look at the metadata, the accented characters turn into "?" in the Subject and Keyword fields, but not the Title and Author fields. The characters are the same ascii 233 I tried replacing them with octal encoding (\351), which came out the same (Title and Author okay, Subject and Keywords messed up). file encoding is latin-1,unix eol I found a mention on adobe forums, but the answer didn't make sense to me. http://forums.adobe.com/message/1165593 I changed the encoding to utf-8, inserted the characters binarily (in VIM : <Ctrl-v>u00e9), no change. I tried inserting the BOM in a few places, it didn't work. This is with Acrobat Pro 9 I didn't notice this problem with Acrobat Pro 7. Does anybody know of a workaround to get the accented characters into ALL the metadata fields when modifying a postscript file, or tell me if I'm doing it wrong? It seems weird that different fields would not accept the same bytes.

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  • asp.net mvc Ajax.BeginForm clone.

    - by denis_n
    Hello, I'm using asp.net mvc ajax. The partial view is using Ajax.BeginForm (just an example): <div id="divPlaceholder"> <% using (Ajax.BeginForm(new AjaxOptions { UpdateTargetId = "divPlaceholder" })) { %> ... asp.net mvc controls and validation messages <input type="submit" value="Save" /> <% } %> </div> After update, if validation fails, the html is: <div id="divPlaceholder"> <div id="divPlaceholder"> ...form </div> </div> I don't like that the returned html is inserted, instead it should replace original div. Probably on POST I should not render <div> around form in partial view or render the div without id. What else can I do in this situation? I was thinking that maybe I should write a helper, something like Ajax.DivBeginForm, which will render form inside div on GET and hide the div on POST. Can somebody provide a good advice how to write such helper (Ajax.DivBeginForm)? I'd like it to work with using keyword: <% using (Ajax.DivBeginForm(new AjaxOptions { UpdateTargetId = "myId" })) { ... }%>

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  • implement SIMD in C++

    - by Hristo
    I'm working on a bit of code and I'm trying to optimize it as much as possible, basically get it running under a certain time limit. The following makes the call... static affinity_partitioner ap; parallel_for(blocked_range<size_t>(0, T), LoopBody(score), ap); ... and the following is what is executed. void operator()(const blocked_range<size_t> &r) const { int temp; int i; int j; size_t k; size_t begin = r.begin(); size_t end = r.end(); for(k = begin; k != end; ++k) { // for each trainee temp = 0; for(i = 0; i < N; ++i) { // for each sample int trr = trRating[k][i]; int ei = E[i]; for(j = 0; j < ei; ++j) { // for each expert temp += delta(i, trr, exRating[j][i]); } } myscore[k] = temp; } } I'm using Intel's TBB to optimize this. But I've also been reading about SIMD and SSE2 and things along that nature. So my question is, how do I store the variables (i,j,k) in registers so that they can be accessed faster by the CPU? I think the answer has to do with implementing SSE2 or some variation of it, but I have no idea how to do that. Any ideas? Thanks, Hristo

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  • Advantage Database Server ORDER BY behaviour

    - by ie
    I'm using ADS v10 beta. I'm trying to numerate ordered resultset. 1) ORDER BY in nested queries. I need to use nested SELECT for some calculations: SELECT Name, Value, ROWNUM() FROM (SELECT * FROM MainTable WHERE Value > 0 ORDER BY Value) a And I'm getting Expected lexical element not found: ) There was a problem parsing the table names after the FROM keyword in your SELECT statement. Everything is working well when the ORDER BY is removed. Although, I found the sample in the Help, it looks like my query (more complex, indeed): SELECT * FROM (SELECT TOP 10 empid, fullname FROM branch1 ORDER BY empid) a UNION SELECT empid, fullname FROM branch2 ORDER BY empid 2) ORDER BY + ROWNUM(). I used the nested query in the example above, to numerate ordered rows. Is there are any chance to avoid nested query? In the SQL Server I can do something like this: SELECT Name, Value, ROW_NUMBER() OVER(ORDER BY Value) FROM MainTable WHERE Value > 1 ORDER BY Value Please advice. Thanks.

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  • How do I get rid of these warnings?

    - by Brian Postow
    This is really several questions, but anyway... I'm working with a big project in XCode, relatively recently ported from MetroWorks (Yes, really) and there's a bunch of warnings that I want to get rid of. Every so often an IMPORTANT warning comes up, but I never look at them because there's too many garbage ones. So, if I can either figure out how to get XCode to stop giving the warning, or actually fix the problem, that would be great. Here are the warnings: It claims that <map.h> is antiquated. However, when I replace it with <map> my files don't compile. Evidently, there's something in map.h that isn't in map... this decimal constant is unsigned only in ISO C90 This is a large number being compared to an unsigned long. I have even cast it, with no effect. enumeral mismatch in conditional expression: <anonymous enum> vs <anonymous enum> This appears to be from a ?: operator. Possibly that the then and else branches don't evaluate to the same type? Except that in at least one case, it's (matchVp == NULL ? noErr : dupFNErr) And since those are both of type OSErr, which is mac defined... I'm not sure what's up. It also seems to come up when I have other pairs of mac constants... multi-character character constant This one is obvious. The problem is that I actually NEED multi-character constants... -fwritable-strings not compatible with literal CF/NSString I unchecked the "Strings are Read-Only" box in both the project and target settings... and it seems to have had no effect...

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  • php parsing speed optimization

    - by Arnaud
    I would like to add tooltip or generate link according to the element available in the database, for exemple if the html page printed is: to reboot your linux host in single-user mode you can ... I will use explode(" ", $row[page]) and the idea is now to lookup for every single word in the page to find out if they have a related referance in this exemple let's say i've got a table referance an one entry for reboot and one for linux reboot: restart a computeur linux: operating system now my output will look like (replaced < and by @) to @a href="ref/reboot"@reboot@/a@ your @a href="ref/linux"@linux@/a@ host in single-user mode you can ... Instead of have a static list generated when I saved the content, if I add more keyword in the future, then the text will become more interactive. My main concerne and question is how can I create a efficient enough process to do it ? Should I store all the db entry in an array and compare them ? Do an sql query for each word (seems to be crazy) Dump the table in a file and use a very long regex or a "grep -f pattern data" way of doing it? Or or or or I'm sure it must be a better way of doing it, just don't have a clue about it, or maybe this will be far too resource un-friendly and I should avoid doing such things. Cheers!

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  • Template compiling errors on iPhone SDK 3.2

    - by Didier Malenfant
    I'm porting over some templated code from Windows and I'm hitting some compiler differences on the iPhone 3.2 SDK. Original code inside a class template's member function is: return BinarySearch<uint32, CSimpleKey<T> >(key); where BinarySearch is a method inherited from another template. This produces the following error: csimplekeytable.h:131: error: no matching function for call to 'BinarySearch(NEngine::uint32&)' The visual studio compiler seems to walk up the template hierarchy fine but gcc needs me to fully qualify where the function comes from (I have verified this by fixing the same issues with template member variables that way). So I now need to change this into: return CSimpleTable<CSimpleKey<T> >::BinarySearch<uint32, CSimpleKey<T> >(key); Which now produces the following error: csimplekeytable.h:132: error: expected primary-expression before ',' token csimplekeytable.h:132: error: expected primary-expression before '>' token After some head scratching, I believe what's going on here is that it's trying to resolve the '<' before BinarySearch as a 'Less Than' operator for some reason. So two questions: - Am I on the right path with my interpretation of the error? - How do I fix it? -D

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  • Is there a language with native pass-by-reference/pass-by-name semantics, which could be used in mod

    - by Bubba88
    Hi! This is a reopened question. I look for a language and supporting platform for it, where the language could have pass-by-reference or pass-by-name semantics by default. I know the history a little, that there were Algol, Fortran and there still is C++ which could make it possible; but, basically, what I look for is something more modern and where the mentioned value pass methodology is preferred and by default (implicitly assumed). I ask this question, because, to my mind, some of the advantages of pass-by-ref/name seem kind of obvious. For example when it is used in a standalone agent, where copyiong of values is not necessary (to some extent) and performance wouldn't be downgraded much in that case. So, I could employ it in e.g. rich client app or some game-style or standalone service-kind application. The main advantage to me is the clear separation between identity of a symbol, and its current value. I mean when there is no reduntant copying, you know that you're working with the exact symbol/path you have queried/received. And intristing boxing of values will not interfere with the actual logic of program. I know that there is C# ref keyword, but it's something not so intristic, though acceptable. Equally, I realize that pass-by-reference semantics could be simulated in virtually any language (Java as an instant example) and so on.. not sure about pass by name :) What would you recommend - create a something like DSL for such needs wherever it be appropriate; or use some languages that I already know? Maybe, there is something that I'm missing? Thank you!

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  • Specializing a class template constructor

    - by SilverSun
    I'm messing around with template specialization and I ran into a problem with trying to specialize the constructor based on what policy is used. Here is the code I am trying to get to work. #include <cstdlib> #include <ctime> class DiePolicies { public: class RollOnConstruction { }; class CallMethod { }; }; #include <boost/static_assert.hpp> #include <boost/type_traits/is_same.hpp> template<unsigned sides = 6, typename RollPolicy = DiePolicies::RollOnConstruction> class Die { // policy type check BOOST_STATIC_ASSERT(( boost::is_same<RollPolicy, DiePolicies::RollOnConstruction>::value || boost::is_same<RollPolicy, DiePolicies::CallMethod>::value )); unsigned m_die; unsigned random() { return rand() % sides; } public: Die(); void roll() { m_die = random(); } operator unsigned () { return m_die + 1; } }; template<unsigned sides> Die<sides, DiePolicies::RollOnConstruction>::Die() : m_die(random()) { } template<unsigned sides> Die<sides, DiePolicies::CallMethod>::Die() : m_die(0) { } ...\main.cpp(29): error C3860: template argument list following class template name must list parameters in the order used in template parameter list ...\main.cpp(29): error C2976: 'Die' : too few template arguments ...\main.cpp(31): error C3860: template argument list following class template name must list parameters in the order used in template parameter list Those are the errors I get in Microsoft Visual Studio 2010. I'm thinking either I can't figure out the right syntax for the specialization, or maybe it isn't possible to do it this way.

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  • Can't get RDFlib to work on windows

    - by john
    I have installed RDFlib 3.0 and everything that is needed, but when I run the following code I get an error. The code below is from: http://code.google.com/p/rdflib/wiki/IntroSparql. I have tried for hours to fix this but with no success. Can please someone help? import rdflib rdflib.plugin.register('sparql', rdflib.query.Processor, 'rdfextras.sparql.processor', 'Processor') rdflib.plugin.register('sparql', rdflib.query.Result, 'rdfextras.sparql.query', 'SPARQLQueryResult') from rdflib import ConjunctiveGraph g = ConjunctiveGraph() g.parse("http://bigasterisk.com/foaf.rdf") g.parse("http://www.w3.org/People/Berners-Lee/card.rdf") from rdflib import Namespace FOAF = Namespace("http://xmlns.com/foaf/0.1/") g.parse("http://danbri.livejournal.com/data/foaf") [g.add((s, FOAF['name'], n)) for s,_,n in g.triples((None, FOAF['member_name'], None))] for row in g.query( """SELECT ?aname ?bname WHERE { ?a foaf:knows ?b . ?a foaf:name ?aname . ?b foaf:name ?bname . }""", initNs=dict(foaf=Namespace("http://xmlns.com/foaf/0.1/"))): print "%s knows %s" % row The error I get is: Traceback (most recent call last): File "...", line 18 in <module> initNs=dict(foaf=Namespace("http://xmlns.com/foaf/0.1/"))): TypeError: query() got an unexpected keyword argument 'initNS'

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  • How to use multifieldquery and filters in Lucene.net

    - by Khotu Nam
    I want to perform a multi field search on a lucene.net index but filter the results based on one of the fields. Here's what I'm currently doing: To index the fields the definitions are: doc.Add(new Field("id", id.ToString(), Field.Store.YES, Field.Index.UN_TOKENIZED)); doc.Add(new Field("title", title, Field.Store.NO, Field.Index.TOKENIZED)); doc.Add(new Field("summary", summary, Field.Store.NO, Field.Index.TOKENIZED, Field.TermVector.YES)); doc.Add(new Field("description", description, Field.Store.NO, Field.Index.TOKENIZED, Field.TermVector.YES)); doc.Add(new Field("distribution", distribution, Field.Store.NO, Field.Index.UN_TOKENIZED)); When I perform the search I do the following: MultiFieldQueryParser parser = new MultiFieldQueryParser(new string[]{"title", "summary", "description"}, analyzer); parser.SetDefaultOperator(QueryParser.Operator.AND); Query query = parser.Parse(text); BooleanQuery bq = new BooleanQuery(); TermQuery tq = new TermQuery(new Term("distribution", distribution)); bq.Add(tq, BooleanClause.Occur.MUST); Filter filter = new QueryFilter(bq); Hits hits = searcher.Search(query, filter); However, the result is always 0 hits. What am I doing wrong?

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  • Tell me SQL Server Full-Text searcher is crazy, not me.

    - by Ian Boyd
    i have some customers with a particular address that the user is searching for: 123 generic way There are 5 rows in the database that match: ResidentialAddress1 ============================= 123 GENERIC WAY 123 GENERIC WAY 123 GENERIC WAY 123 GENERIC WAY 123 GENERIC WAY i run a FT query to look for these rows. i'll show you each step as i add more criteria to the search: SELECT ResidentialAddress1 FROM Patrons WHERE CONTAINS(Patrons.ResidentialAddress1, '"123*"') ResidentialAddress1 ========================= 123 MAPLE STREET 12345 TEST 123 MINE STREET 123 GENERIC WAY 123 FAKE STREET ... (30 row(s) affected) Okay, so far so good, now adding the word "generic": SELECT ResidentialAddress1 FROM Patrons WHERE CONTAINS(Patrons.ResidentialAddress1, '"123*"') AND CONTAINS(Patrons.ResidentialAddress1, '"generic*"') ResidentialAddress1 ============================= 123 GENERIC WAY 123 GENERIC WAY 123 GENERIC WAY 123 GENERIC WAY 123 GENERIC WAY (5 row(s) affected) Excellent. And now i'l add the final keyword that the user wants to make sure exists: SELECT ResidentialAddress1 FROM Patrons WHERE CONTAINS(Patrons.ResidentialAddress1, '"123*"') AND CONTAINS(Patrons.ResidentialAddress1, '"generic*"') AND CONTAINS(Patrons.ResidentialAddress1, '"way*"') ResidentialAddress1 ------------------------------ (0 row(s) affected) Huh? No rows? What if i query for just "way*": SELECT ResidentialAddress1 FROM Patrons WHERE CONTAINS(Patrons.ResidentialAddress1, '"way*"') ResidentialAddress1 ------------------------------ (0 row(s) affected) At first i thought that perhaps it's because of the *, and it's requiring that the root way have more characters after it. But that's not true: Searching for "123*" matches "123" Searching for "generic*" matches "generic" Books online says, The asterisk matches zero, one, or more characters What if i remove the * just for s&g: SELECT ResidentialAddress1 FROM Patrons WHERE CONTAINS(Patrons.ResidentialAddress1, '"way"') Server: Msg 7619, Level 16, State 1, Line 1 A clause of the query contained only ignored words. So one might think that you are just not allowed to even search for way, either alone, or as a root. But this isn't true either: SELECT * FROM Patrons WHERE CONTAINS(Patrons.*, '"way*"') AccountNumber FirstName Lastname ------------- --------- -------- 33589 JOHN WAYNE So sum up, the user is searching for rows that contain all the words: 123 generic way Which i, correctly, translate into the WHERE clauses: SELECT * FROM Patrons WHERE CONTAINS(Patrons.*, '"123*"') AND CONTAINS(Patrons.*, '"generic*"') AND CONTAINS(Patrons.*, '"way*"') which returns no rows. Tell me this just isn't going to work, that it's not my fault, and SQL Server is crazy. Note: i've emptied the FT index and rebuilt it.

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  • IEnumerable.Cast not calling cast overload

    - by Martin Neal
    I'm not understanding something about the way .Cast works. I have an explicit (though implicit also fails) cast defined which seems to work when I use it "regularly", but not when I try to use .Cast. Why? Here is some compilable code that demonstrates my problem. public class Class1 { public string prop1 { get; set; } public int prop2 { get; set; } public static explicit operator Class2(Class1 c1) { return new Class2() { prop1 = c1.prop1, prop2 = c1.prop2 }; } } public class Class2 { public string prop1 { get; set; } public int prop2 { get; set; } } void Main() { Class1[] c1 = new Class1[] { new Class1() {prop1 = "asdf",prop2 = 1}}; //works Class2 c2 = (Class2)c1[0]; //doesn't work: Compiles, but throws at run-time //InvalidCastException: Unable to cast object of type 'Class1' to type 'Class2'. Class2 c3 = c1.Cast<Class2>().First(); }

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  • Why does C++ not allow multiple types in one auto statement?

    - by Walter
    The 2011 C++ standard introduced the new keyword auto, which can be used for defining variables instead of a type, i.e. auto p=make_pair(1,2.5); // pair<int,double> auto i=std::begin(c), end=std::end(c); // decltype(std::begin(c)) In the second line, i and end are of the same type, referred to as auto. The standard does not allow auto i=std::begin(container), e=std::end(container), x=*i; when x would be of different type. My question: why does the standard not allow this last line? It could be allowed by interpreting auto not as representing some to-be-decuded type, but as indicating that the type of any variable declared auto shall be deduced from its assigned value. Is there any good reason for the C++11 standard to not follow this approach? There is actually a use case for this, namely in the initialisation statement of for loops: for(auto i=std::begin(c), end=std::end(c), x=*i; i!=end; ++i, x+=*i) { ... } when the scope of the variables i, end, and x is limited to the for loop. AFAIK, this cannot be achieved in C++ unless those variables have a common type. Is this correct? (ugly tricks of putting all types inside a struct excluded) There may also be use cases in some variadic template applications.

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  • Display a ranking grid for game : optimization of left outer join and find a player

    - by Jerome C.
    Hello, I want to do a ranking grid. I have a table with different values indexed by a key: Table SimpleValue : key varchar, value int, playerId int I have a player which have several SimpleValue. Table Player: id int, nickname varchar Now imagine these records: SimpleValue: Key value playerId for 1 1 int 2 1 agi 2 1 lvl 5 1 for 6 2 int 3 2 agi 1 2 lvl 4 2 Player: id nickname 1 Bob 2 John I want to display a rank of these players on various SimpleValue. Something like: nickname for lvl Bob 1 5 John 6 4 For the moment I generate an sql query based on which SimpleValue key you want to display and on which SimpleValue key you want to order players. eg: I want to display 'lvl' and 'for' of each player and order them on the 'lvl' The generated query is: SELECT p.nickname as nickname, v1.value as lvl, v2.value as for FROM Player p LEFT OUTER JOIN SimpleValue v1 ON p.id=v1.playerId and v1.key = 'lvl' LEFT OUTER JOIN SimpleValue v2 ON p.id=v2.playerId and v2.key = 'for' ORDER BY v1.value This query runs perfectly. BUT if I want to display 10 different values, it generates 10 'left outer join'. Is there a way to simplify this query ? I've got a second question: Is there a way to display a portion of this ranking. Imagine I've 1000 players and I want to display TOP 10, I use the LIMIT keyword. Now I want to display the rank of the player Bob which is 326/1000 and I want to display 5 rank player above and below (so from 321 to 331 position). How can I achieve it ? thanks.

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  • C# Hiding, overriding and calling function from base class.

    - by Lukasz Lysik
    I'm learning C# and I encountered the following problem. I have two classes: base and derived: class MyBase { public void MyMethod() { Console.WriteLine("MyBase::MyMethod()"); } } class MyDerived: MyBase { public void MyMethod() { Console.WriteLine("MyDerived::MyMethod()"); } } For now, without virtual and override key words. When I compile this I get the warning (which is of course expected) that I try to hide MyMethod from MyBase class. What I want to do is to call the method from the base class having an instance of derived class. I do this like this: MyDerived myDerived = new MyDerived(); ((MyBase)myDerived).MyMethod(); It works fine when I do not specify any virtual, etc. keywords in the methods. I tried to put combination of the keywords and I got the following results: | MyBase::MyMethod | MyDerived::MyMethod | Result printed on the console | | -----------------|---------------------|-------------------------------| | - | - | MyBase::MyMethod() | | - | new | MyBase::MyMethod() | | virtual | new | MyBase::MyMethod() | | virtual | override | MyDerived::MyMethod() | I hope the table is clear to you. I have two questions: Is it the correct way to call the function from the base class (((MyBase)myDerived).MyMethod();)? I know about base keyword, but it can be called only from the inside of the derived class. Is it right? Why in the last case (with virtual and override modifiers) the method which was called came from the derived class? Would you please explain that?

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  • Indentation control while developing a small python like language

    - by sap
    Hello, I'm developing a small python like language using flex, byacc (for lexical and parsing) and C++, but i have a few questions regarding scope control. just as python it uses white spaces (or tabs) for indentation, not only that but i want to implement index breaking like for instance if you type "break 2" inside a while loop that's inside another while loop it would not only break from the last one but from the first loop as well (hence the number 2 after break) and so on. example: while 1 while 1 break 2 'hello world'!! #will never reach this. "!!" outputs with a newline end 'hello world again'!! #also will never reach this. again "!!" used for cout end #after break 2 it would jump right here but since I don't have an "anti" tab character to check when a scope ends (like C for example i would just use the '}' char) i was wondering if this method would the the best: I would define a global variable, like "int tabIndex" on my yacc file that i would access in my lex file using extern. then every time i find a tab character on my lex file i would increment that variable by 1. when parsing on my yacc file if i find a "break" keyword i would decrement by the amount typed after it from the tabIndex variable, and when i reach and EOF after compiling and i get a tabIndex != 0 i would output compilation error. now the problem is, whats the best way to see if the indentation got reduced, should i read \b (backspace) chars from lex and then reduce the tabIndex variable (when the user doesn't use break)? another method to achieve this? also just another small question, i want every executable to have its starting point on the function called start() should i hardcode this onto my yacc file? sorry for the long question any help is greatly appreciated. also if someone can provide an yacc file for python would be nice as a guideline (tried looking on Google and had no luck). thanks in advance.

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  • Trouble with Unions in C program.

    - by Jordan S
    I am working on a C program that uses a Union. The union definition is in FILE_A header file and looks like this... // FILE_A.h**************************************************** xdata union { long position; char bytes[4]; }CurrentPosition; If I set the value of CurrentPosition.position in FILE_A.c and then call a function in FILE_B.c that uses the union, the data in the union is back to Zero. This is demonstrated below. // FILE_A.c**************************************************** int main.c(void) { CurrentPosition.position = 12345; SomeFunctionInFileB(); } // FILE_B.c**************************************************** void SomeFunctionInFileB(void) { // After the following lines execute I see all zeros in the flash memory. WriteByteToFlash(CurrentPosition.bytes[0]; WriteByteToFlash(CurrentPosition.bytes[1]; WriteByteToFlash(CurrentPosition.bytes[2]; WriteByteToFlash(CurrentPosition.bytes[3]; } Now, If I pass a long to SomeFunctionInFileB(long temp) and then store it into CurrentPosition.bytes within that function, and finally call WriteBytesToFlash(CurrentPosition.bytes[n]... it works just fine. It appears as though the CurrentPosition Union is not global. So I tried changing the union definition in the header file to include the extern keyword like this... extern xdata union { long position; char bytes[4]; }CurrentPosition; and then putting this in the source (.c) file... xdata union { long position; char bytes[4]; }CurrentPosition; but this causes a compile error that says: C:\SiLabs\Optec Programs\AgosRot\MotionControl.c:76: error 91: extern definition for 'CurrentPosition' mismatches with declaration. C:\SiLabs\Optec Programs\AgosRot\/MotionControl.h:48: error 177: previously defined here So what am I doing wrong? How do I make the union global?

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