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  • Measure width() with jQuery after DOM refresh

    - by o_O Tync
    My script dynamically creates a <ul> width left-floating <li>s inside: it's a paginator. Afterwards, the script measures width of all <li>s and summs them up. The problem is that after the nodes are injected into the document — the browser refreshed DOM and applies CSS styles which takes a while. It has a negative effect on my script: when these operations are not complete before I measure the width — my script gets a wrong value. If I perform the measure in a second — everything is ok. The thing I'm looking for is a way to detect the moment when the <ul> is fully drawn, styles applied and the width has stabilizes. Or at least a way to detect every dimensions changes. Of course I can use setTimeout(..., 100) but it's ugly and I guess — not a solution at all. If there's a way to detect width stabilization — I would do the measuring right after it to get the correct values. HTML code generated by the DOM <div> <ul> <li><a href="...">1</a></li> <li><a href="...">2</a></li> .... </ul> </div> P.S. Why I need this. My paginator's left-floating <li> items tend to move to the next line when the <ul> tries to become wider than the page itself. Even though most of <li>s are invisible because of parent <div>'s width restriction: div { width: 500px; overflow: hidden; } div ul { width: 100%; white-space: nowrap; } div ul li { display: block; float: left; } they still go down unless I specify the actual summed width of the <ul> with the script.

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  • Hibernate3: Self-Referencing Objects

    - by monojohnny
    Need some help on understanding how to do this; I'm going to be running recursive 'find' on a file system and I want to keep the information in a single DB table - with a self-referencing hierarchial structure: This is my DB Table structure I want to populate. DirObject Table: id int NOT NULL, name varchar(255) NOT NULL, parentid int NOT NULL); Here is the proposed Java Class I want to map (Fields only shown): public DirObject { int id; String name; DirObject parent; ... For the 'root' directory was going to use parentid=0; real ids will start at 1, and ideally I want hibernate to autogenerate the ids. Can somebody provide a suggested mapping file for this please; as a secondary question I thought about doing the Java Class like this instead: public DirObject { int id; String name; List<DirObject> subdirs; Could I use the same data model for either of these two methods ? (With a different mapping file of course). --- UPDATE: so I tried the mapping file suggested below (thanks!), repeated here for reference: <hibernate-mapping> <class name="my.proj.DirObject" table="category"> ... <set name="subDirs" lazy="true" inverse="true"> <key column="parentId"/> <one-to-many class="my.proj.DirObject"/> </set> <many-to-one name="parent" class="my.proj.DirObject" column="parentId" cascade="all" /> </class> ...and altered my Java class to have BOTH 'parentid' and 'getSubDirs' [returning a 'HashSet']. This appears to work - thanks, but this is the test code I used to drive this - I think I'm not doing something right here, because I thought Hibernate would take care of saving the subordinate objects in the Set without me having to do this explicitly ? DirObject dirobject=new DirObject(); dirobject.setName("/files"); dirobject.setParent(dirobject); DirObject d1, d2; d1=new DirObject(); d1.setName("subdir1"); d1.setParent(dirobject); d2=new DirObject(); d2.setName("subdir2"); d2.setParent(dirobject); HashSet<DirObject> subdirs=new HashSet<DirObject>(); subdirs.add(d1); subdirs.add(d2); dirobject.setSubdirs(subdirs); session.save(dirobject); session.save(d1); session.save(d2);

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  • JAVA - Strange problem (probably thread problem) with JTable & Model

    - by Stefanos Kargas
    I am using 2 Tables (JTable) with their DefaultTableModels. The first table is already populated. The second table is populated for each row of the first table (using an SQL Query). My purpose is to export every line of the first table with it's respective lines of the second in an Excel File. I am doing it with a for (for each line of 1st table), in which I write a line of the 1st table in the Excel File, then I populate the 2nd table (for this line of 1st Table), I get every line from the Table (from it's Model actually) and put it in the Excel File under the current line of 1st table. This means that if I have n lines in first table I will clear and populate again the second table n times. All this code is called in a seperate thread. THE PROBLEM IS: Everything works perfectly fine ecxept that I am getting some exceptions. The strange thing is that I'm not getting anything false in my result. The Excel file is perfect. Some of the lines of the exceptions are: Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 0 = 0 at java.util.Vector.elementAt(Vector.java:427) at javax.swing.table.DefaultTableModel.getValueAt(DefaultTableModel.java:632) at javax.swing.JComponent.paint(JComponent.java:1017) at javax.swing.RepaintManager.paint(RepaintManager.java:1220) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:803) I am assuming that the problem lies in the fact that the second table needs some more time to be populated before I try to get any data from it. That's why I see RepaintManager and paintDirtyRegions in my exceptions. Another thing I did is that I ran my program in debug mode and I put a breakpoint after each population of the 2nd table. Then I pressed F5 to continue for each population of 2nd table and no exception appeared. The program came to it's end without any exceptions. This is another important fact that tells me that maybe in this case I gave the table enough time to be populated. Of course you will ask me: If your program works fine, why do you care about the exceptions? I care for avoiding any future problems and I care to have a better understanding of Java and Java GUI and threads. Why do you depend on a GUI component (and it's model) to get your information and why don't you recreate the resultset that populates your tables using an SQL Query and get your info from the resultset? That would be the best and the right way. The fact is that I have the tables code ready and it was easier for me to just get the info from them. But the right way would be to get everything direct from database. Anyway what I did brought out my question, and answering it would help me understand more things about java. So I posted it.

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  • In a PHP project, how do you organize and access your helper objects?

    - by Pekka
    How do you organize and manage your helper objects like the database engine, user notification, error handling and so on in a PHP based, object oriented project? Say I have a large PHP CMS. The CMS is organized in various classes. A few examples: the database object user management an API to create/modify/delete items a messaging object to display messages to the end user a context handler that takes you to the right page a navigation bar class that shows buttons a logging object possibly, custom error handling etc. I am dealing with the eternal question, how to best make these objects accessible to each part of the system that needs it. my first apporach, many years ago was to have a $application global that contained initialized instances of these classes. global $application; $application->messageHandler->addMessage("Item successfully inserted"); I then changed over to the Singleton pattern and a factory function: $mh =&factory("messageHandler"); $mh->addMessage("Item successfully inserted"); but I'm not happy with that either. Unit tests and encapsulation become more and more important to me, and in my understanding the logic behind globals/singletons destroys the basic idea of OOP. Then there is of course the possibility of giving each object a number of pointers to the helper objects it needs, probably the very cleanest, resource-saving and testing-friendly way but I have doubts about the maintainability of this in the long run. Most PHP frameworks I have looked into use either the singleton pattern, or functions that access the initialized objects. Both fine approaches, but as I said I'm happy with neither. I would like to broaden my horizon on what is possible here and what others have done. I am looking for examples, additional ideas and pointers towards resources that discuss this from a long-term, real-world perspective. Also, I'm interested to hear about specialized, niche or plain weird approaches to the issue. Bounty I am following the popular vote in awarding the bounty, the answer which is probably also going to give me the most. Thank you for all your answers!

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  • Setting up Netbeans/Eclipse for Linux Kernel Development

    - by red.october
    Hi: I'm doing some Linux kernel development, and I'm trying to use Netbeans. Despite declared support for Make-based C projects, I cannot create a fully functional Netbeans project. This is despite compiling having Netbeans analyze a kernel binary that was compiled with full debugging information. Problems include: files are wrongly excluded: Some files are incorrectly greyed out in the project, which means Netbeans does not believe they should be included in the project, when in fact they are compiled into the kernel. The main problem is that Netbeans will miss any definitions that exist in these files, such as data structures and functions, but also miss macro definitions. cannot find definitions: Pretty self-explanatory - often times, Netbeans cannot find the definition of something. This is partly a result of the above problem. can't find header files: self-explanatory I'm wondering if anyone has had success with setting up Netbeans for Linux kernel development, and if so, what settings they used. Ultimately, I'm looking for Netbeans to be able to either parse the Makefile (preferred) or extract the debug information from the binary (less desirable, since this can significantly slow down compilation), and automatically determine which files are actually compiled and which macros are actually defined. Then, based on this, I would like to be able to find the definitions of any data structure, variable, function, etc. and have complete auto-completion. Let me preface this question with some points: I'm not interested in solutions involving Vim/Emacs. I know some people like them, but I'm not one of them. As the title suggest, I would be also happy to know how to set-up Eclipse to do what I need While I would prefer perfect coverage, something that only misses one in a million definitions is obviously fine SO's useful "Related Questions" feature has informed me that the following question is related: http://stackoverflow.com/questions/149321/what-ide-would-be-good-for-linux-kernel-driver-development. Upon reading it, the question is more of a comparison between IDE's, whereas I'm looking for how to set-up a particular IDE. Even so, the user Wade Mealing seems to have some expertise in working with Eclipse on this kind of development, so I would certainly appreciate his (and of course all of your) answers. Cheers

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  • getline() sets failbit and skips last line

    - by Thanatos
    I'm using std::getline() to enumerate through the lines in a file, and it's mostly working. It's left me curious however - std::getline() is skipping the very last line in my file, but only if it's blank. Using this minimal example: #include <iostream> #include <string> int main() { std::string line; while(std::getline(std::cin, line)) std::cout << "Line: “" << line << "”\n"; return 0; } If I feed it this: Line A Line B Line C I get those lines back at me. But this: Line A Line B Line C [* line is present but blank, ie, the file end is: "...B\nLine C\n" *] (I unfortunately can't have a blank line in SO's little code box thing...) So, first file has three lines ( ["Line A", "Line B", "Line C"] ), second file has four ( ["Line A", "Line B", "Line C", ""] ) This to me seems wrong - I have a four line file, and enumerating it with getline() leaves me with 3. What's really got me scratching my head is that this is exactly what the standard says it should do. (21.3.7.9) Even Python has similar behaviour (but it gives me the newlines too - C++ chops them off.) Is this some weird thing where C++ is expected lines to be terminated, and not separated by '\n', and I'm feeding it differently? Edit Clearly, I need to expand a bit here. I've met up with two philosophies of determining what a "line" in a file is: Lines are terminated by newlines - Dominant in systems such as Linux, and editors like vim. Possible to have a slightly "odd" file by not having a final '\n' (a "noeol" in vim). Impossible to have a blank line at the end of a file. Lines are separated by newlines - Dominant in just about every Windows editor I've ever come across. Every file is valid, and it's possible to have the last line be blank. Of course, YMMV as to what a newline is. I've always treated these as two completely different schools of thought. One earlier point I tried to make was to ask if the C++ standard was explicitly or merely implicitly following the first. (Curiously, where is Mac? terminated or separated?)

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  • .NET: Is there a way to finagle a default namespace in an XPath 1.0 query?

    - by Cheeso
    I'm building a tool that performs xpath 1.0 queries on XHTML documents. The requirement to use a namespace prefix in the query is killing me. The query looks like this: html/body/div[@class='contents']/div[@class='body']/ div[@class='pgdbbyauthor']/h2[a[@name][starts-with(.,'Quick')]]/ following-sibling::ul[1]/li/a (all on one line) ...which is bad enough, except because it's xpath 1.0, I need to use an explicit namespace prefix on each QName, so it looks like this: ns1:html/ns1:body/ns1:div[@class='contents']/ns1:div[@class='body']/ ns1:div[@class='pgdbbyauthor']/ns1:h2[ns1:a[@name][starts-with(.,'Quick')]]/ following-sibling::ns1:ul[1]/ns1:li/ns1:a To set up the query, I do something like this: var xpathDoc = new XPathDocument(new StringReader(theText)); var nav = xpathDoc.CreateNavigator(); var xmlns = new XmlNamespaceManager(nav.NameTable); foreach (string prefix in xmlNamespaces.Keys) xmlns.AddNamespace(prefix, xmlNamespaces[prefix]); XPathNodeIterator selection = nav.Select(xpathExpression, xmlns); But what I want is for the xpathExpression to use the implicit default namespace. Is there a way for me to transform the unadorned xpath expression, after it's been written, to inject a namespace prefix for each element name in the query? I'm thinking, anything between two slashes, I could inject a prefix there. Excepting of course axis names like "parent::" and "preceding-sibling::" . And wildcards. That's what I mean by "finagle a default namespace". Is this hack gonna work? Addendum Here's what I mean. suppose I have an xpath expression, and before passing it to nav.Select(), I transform it. Something like this: string FixupWithDefaultNamespace(string expr) { string s = expr; s = Regex.Replace(s, "^(?!::)([^/:]+)(?=/)", "ns1:$1"); // beginning s = Regex.Replace(s, "/([^/:]+)(?=/)", "/ns1:$1"); // stanza s = Regex.Replace(s, "::([A-Za-z][^/:*]*)(?=/)", "::ns1:$1"); // axis specifier s = Regex.Replace(s, "\\[([A-Za-z][^/:*\\(]*)(?=[\\[\\]])", "[ns1:$1"); // predicate s = Regex.Replace(s, "/([A-Za-z][^/:]*)(?!<::)$", "/ns1:$1"); // end s = Regex.Replace(s, "^([A-Za-z][^/:]*)$", "ns1:$1"); // edge case s = Regex.Replace(s, "([-A-Za-z]+)\\(([^/:\\.,\\)]+)(?=[,\\)])", "$1(ns1:$2"); // xpath functions return s; } This actually works for simple cases I tried. To use the example from above - if the input is the first xpath expression, the output I get is the 2nd one, with all the ns1 prefixes. The real question is, is it hopeless to expect this Regex.Replace approach to work, as the xpath expressions get more complicated?

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  • Moving a unit precisely along a path in x,y coordinates

    - by Adam Eberbach
    I am playing around with a strategy game where squads move around a map. Each turn a certain amount of movement is allocated to a squad and if the squad has a destination the points are applied each turn until the destination is reached. Actual distance is used so if a squad moves one position in the x or y direction it uses one point, but moving diagonally takes ~1.4 points. The squad maintains actual position as float which is then rounded to allow drawing the position on the map. The path is described by touching the squad and dragging to the end position then lifting the pen or finger. (I'm doing this on an iPhone now but Android/Qt/Windows Mobile would work the same) As the pointer moves x, y points are recorded so that the squad gains a list of intermediate destinations on the way to the final destination. I'm finding that the destinations are not evenly spaced but can be further apart depending on the speed of the pointer movement. Following the path is important because obstacles or terrain matter in this game. I'm not trying to remake Flight Control but that's a similar mechanic. Here's what I've been doing, but it just seems too complicated (pseudocode): getDestination() { - self.nextDestination = remove_from_array(destinations) - self.gradient = delta y to destination / delta x to destination - self.angle = atan(self.gradient) - self.cosAngle = cos(self.angle) - self.sinAngle = sin(self.angle) } move() { - get movement allocation for this turn - if self.nextDestination not valid - - getNextDestination() - while(nextDestination valid) && (movement allocation remains) { - - find xStep and yStep using movement allocation and sinAngle/cosAngle calculated for current self.nextDestination - - if current position + xStep crosses the destination - - - find x movement remaining after self.nextDestination reached - - - calculate remaining direct path movement allocation (xStep remaining / cosAngle) - - - make self.position equal to self.nextDestination - - else - - - apply xStep and yStep to current position - } - round squad's float coordinates to integer screen coordinates - draw squad image on map } That's simplified of course, stuff like sign needs to be tweaked to ensure movement is in the right direction. If trig is the best way to do it then lookup tables can be used or maybe it doesn't matter on modern devices like it used to. Suggestions for a better way to do it? an update - iPhone has zero issues with trig and tracking tens of positions and tracks implemented as described above and it draws in floats anyway. The Bresenham method is more efficient, trig is more precise. If I was to use integer Bresenham I would want to multiply by ten or so to maintain a little more positional accuracy to benefit collisions/terrain detection.

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  • Browser detection Plugin?

    - by chobo2
    Hi I have a website that I made and I am planning to redo it. The current version of the site used a jquery callout plugin that did not fully work in IE6. This got me thinking about browser detection. At first I was just going to put the supported browsers on the home page but then today on Digg I saw some post about some jquery plugins and wordpress and in the article there was a plugin for detecting IE. So I started to look around for some browser detection plugins. I found a few of them but they where over the top like this one sevenup Its nice but it makes a huge popup and tells them to update. This one is better then another one I found where they basically forced the user to update or they could not continue on the site. So I found this one jquery plugin This one is pretty nice since it looks at the major browsers and does detection on them too expect for chrome which I noticed triggers and an outdated browser with this plugin. So I started to look at the jquery documentation to see if they had a browser detection for chrome this is when I saw that they "Deprecated" and now recommend "Support". So now I am just confused like "Support" seems to be good and I read many posts on this site saying you should use it. But then it does not support stuff like .png detection that might have been useful to me since of that plugin(however I probably will not be using the plugin anymore since I think the author just gave up on it). Plus I don't know if this is something I am looking for at this time. Like I am guessing with "Support" you use it to detect something that is not supported and then do some alternative thing for that browser? For me I am more looking for something to tell the user "Hey look I tested this browser in the these versions of Firefox(3.5+), IE(8+), Opera(9.5+),Chrome(Something), Safari(Something). If your not using these versions you may not being seeing the site how it was intended" Of course I would try to have something shorter then that message but that the gyst. I am also assuming that the site would work in future versions of these browsers. I still check to see if my site works(they usually do) and is half decent in IE 6 but I won't spend hours fixing stuff that might be off in older browsers like IE 6. I won't test my site in older version of other browsers like firefox since I would think the user have to the sense to update so no point testing firefox 2.0 or whatever. So is there a plugin that fits this description? Or can "Support" do what I want? Thanks

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  • How to define an extern, C struct returning function in C++ using MSVC?

    - by DK
    The following source file will not compile with the MSVC compiler (v15.00.30729.01): /* stest.c */ #ifdef __cplusplus extern "C" { #endif struct Test; extern struct Test make_Test(int x); struct Test { int x; }; extern struct Test make_Test(int x) { struct Test r; r.x = x; return r; } #ifdef __cplusplus } #endif Compiling with cl /c /Tpstest.c produces the following error: stest.c(8) : error C2526: 'make_Test' : C linkage function cannot return C++ class 'Test' stest.c(6) : see declaration of 'Test' Compiling without /Tp (which tells cl to treat the file as C++) works fine. The file also compiles fine in DigitalMars C and GCC (from mingw) in both C and C++ modes. I also used -ansi -pedantic -Wall with GCC and it had no complaints. For reasons I will go into below, we need to compile this file as C++ for MSVC (not for the others), but with functions being compiled as C. In essence, we want a normal C compiler... except for about six lines. Is there a switch or attribute or something I can add that will allow this to work? The code in question (though not the above; that's just a reduced example) is being produced by a code generator. As part of this, we need to be able to generate floating point nans and infinities as constants (long story), meaning we have to compile with MSVC in C++ mode in order to actually do this. We only found one solution that works, and it only works in C++ mode. We're wrapping the code in extern "C" {...} because we want to control the mangling and calling convention so that we can interface with existing C code. ... also because I trust C++ compilers about as far as I could throw a smallish department store. I also tried wrapping just the reinterpret_cast line in extern "C++" {...}, but of course that doesn't work. Pity. There is a potential solution I found which requires reordering the declarations such that the full struct definition comes before the function foward decl., but this is very inconvenient due to the way the codegen is performed, so I'd really like to avoid having to go down that road if I can.

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  • PHP 'instanceof' failing with class constant

    - by Nathan Loding
    I'm working on a framework that I'm trying to type as strongly as I possibly can. (I'm working within PHP and taking some of the ideas that I like from C# and trying to utilize them within this framework.) I'm creating a Collection class that is a collection of domain entities/objects. It's kinda modeled after the List<T> object in .Net. I've run into an obstacle that is preventing me from typing this class. If I have a UserCollection, it should only allow User objects into it. If I have a PostCollection, it should only allow Post objects. All Collections in this framework need to have certain basic functions, such as add, remove, iterate. I created an interface, but found that I couldn't do the following: interface ICollection { public function add($obj) } class PostCollection implements ICollection { public function add(Post $obj) {} } This broke it's compliance with the interface. But I can't have the interface strongly typed because then all Collections are of the same type. So I attempted the following: interface ICollection { public function add($obj) } abstract class Collection implements ICollection { const type = 'null'; } class PostCollection { const type = 'Post'; public function add($obj) { if(!($obj instanceof self::type)) { throw new UhOhException(); } } } When I attempt to run this code, I get syntax error, unexpected T_STRING, expecting T_VARIABLE or '$' on the instanceof statement. A little research into the issue and it looks like the root of the cause is that $obj instanceof self is valid to test against the class. It appears that PHP doesn't process the entire self::type constant statement in the expression. Adding parentheses around the self::type variable threw an error regarding an unexpected '('. An obvious workaround is to not make the type variable a constant. The expression $obj instanceof $this->type works just fine (if $type is declared as a variable, of course). I'm hoping that there's a way to avoid that, as I'd like to define the value as a constant to avoid any possible change in the variable later. Any thoughts on how I can achieve this, or have I take PHP to it's limit in this regard? Is there a way of "escaping" or encapsulating self::this so that PHP won't die when processing it?

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  • jQuery tablesorter - loss of functionality after AJAX call

    - by Nick
    I have recently been experimenting with the tablesorter plugin for jQuery. I have successfully got it up and running in once instance, and am very impressed. However, I have tried to apply the tablesorter to a different table, only to encounter some difficulties... Basically the table causing a problem has a <ul> above it which acts as a set of tabs for the table. so if you click one of these tabs, an AJAX call is made and the table is repopulated with the rows relevant to the specific tab clicked. When the page initially loads (i.e. before a tab has been clicked) the tablesorter functionality works exactly as expected. But when a tab is clicked and the table repopulated, the functionality disappears, rendering it without the sortable feature. Even if you go back to the original tab, after clicking another, the functionality does not return - the only way to do so is a physical refresh of the page in the browser. I have seen a solution which seems similar to my problem on this site, and someone recommends using the jQuery plugin, livequery. I have tried this but to no avail :-( If someone has any suggestions I would be most appreciative. I can post code snippets if it would help (though I know the instantiation code for tablesorter is fine as it works on tables with no tabs - so it's definitely not that!) EDIT: As requested, here are some code snippets: The table being sorted is <table id="#sortableTable#">..</table>, the instantiation code for tablesorter I am using is: $(document).ready(function() { $("#sortableTable").tablesorter( { headers: //disable any headers not worthy of sorting! { 0: { sorter: false }, 5: { sorter: false } }, sortMultiSortKey: 'ctrlKey', debug:true, widgets: ['zebra'] }); }); And I tried to rig up livequery as follows: $("#sortableTable").livequery(function(){ $(this).tablesorter(); }); This has not helped though... I am not sure whether I should use the id of the table with livequery as it is the click on the <ul> I should be responding to, which is of course not part of the table itself. I have tried a number of variations in the hope that one of them will help, but to no avail :-(

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  • Some clarification on rvalue references

    - by Dennis Zickefoose
    First: where are std::move and std::forward defined? I know what they do, but I can't find proof that any standard header is required to include them. In gcc44 sometimes std::move is available, and sometimes its not, so a definitive include directive would be useful. When implementing move semantics, the source is presumably left in an undefined state. Should this state necessarily be a valid state for the object? Obviously, you need to be able to call the object's destructor, and be able to assign to it by whatever means the class exposes. But should other operations be valid? I suppose what I'm asking is, if your class guarantees certain invariants, should you strive to enforce those invariants when the user has said they don't care about them anymore? Next: when you don't care about move semantics, are there any limitations that would cause a non-const reference to be preferred over an rvalue reference when dealing with function parameters? void function(T&); over void function(T&&); From a caller's perspective, being able to pass functions temporary values is occasionally useful, so it seems as though one should grant that option whenever it is feasible to do so. And rvalue references are themselves lvalues, so you can't inadvertently call a move-constructor instead of a copy-constructor, or something like that. I don't see a downside, but I'm sure there is one. Which brings me to my final question. You still can not bind temporaries to non-const references. But you can bind them to non-const rvalue references. And you can then pass along that reference as a non-const reference in another function. void function1(int& r) { r++; } void function2(int&& r) { function1(r); } int main() { function1(5); //bad function2(5); //good } Besides the fact that it doesn't do anything, is there anything wrong with that code? My gut says of course not, since changing rvalue references is kind of the whole point to their existence. And if the passed value is legitimately const, the compiler will catch it and yell at you. But by all appearances, this is a runaround of a mechanism that was presumably put in place for a reason, so I'd just like confirmation that I'm not doing anything foolish.

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  • what to do with a flawed C++ skills test

    - by Mike Landis
    In the following gcc.gnu.org post, Nathan Myers says that a C++ skills test at SANS Consulting Services contained three errors in nine questions: Looking around, one of fthe first on-line C++ skills tests I ran across was: http://www.geekinterview.com/question_details/13090 I looked at question 1... find(int x,int y) { return ((x<y)?0:(x-y)):} call find(a,find(a,b)) use to find (a) maximum of a,b (b) minimum of a,b (c) positive difference of a,b (d) sum of a,b ... immediately wondering why would anyone write anything so obtuse. Getting past the absurdity, I didn't really like any of the answers, immediately eliminating (a) and (b) because you can get back zero (which is neither a nor b) in a variety of circumstances. Sum or difference seemed more likely, except that you could also get zero regardless of the magnitudes of a and b. So... I put Matlab to work (code below) and found: when either a or b is negative you get zero; when b a you get a; otherwise you get b, so the answer is (b) min(a,b), if a and b are positive, though strictly speaking the answer should be none of the above because there are no range restrictions on either variable. That forces test takers into a dilemma - choose the best available answer and be wrong in 3 of 4 quadrants, or don't answer, leaving the door open to the conclusion that the grader thinks you couldn't figure it out. The solution for test givers is to fix the test, but in the interim, what's the right course of action for test takers? Complain about the questions? function z = findfunc(x,y) for i=1:length(x) if x(i) < y(i) z(i) = 0; else z(i) = x(i) - y(i); end end end function [b,d1,z] = plotstuff() k = 50; a = [-k:1:k]; b = (2*k+1) * rand(length(a),1) - k; d1 = findfunc(a,b); z = findfunc(a,d1); plot( a, b, 'r.', a, d1, 'g-', a, z, 'b-'); end

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  • .NET and C# Exceptions. What is it reasonable to catch.

    - by djna
    Disclaimer, I'm from a Java background. I don't do much C#. There's a great deal of transfer between the two worlds, but of course there are differences and one is in the way Exceptions tend to be thought about. I recently answered a C# question suggesting that under some circstances it's reasonable to do this: try { some work } catch (Exeption e) { commonExceptionHandler(); } (The reasons why are immaterial). I got a response that I don't quite understand: until .NET 4.0, it's very bad to catch Exception. It means you catch various low-level fatal errors and so disguise bugs. It also means that in the event of some kind of corruption that triggers such an exception, any open finally blocks on the stack will be executed, so even if the callExceptionReporter fuunction tries to log and quit, it may not even get to that point (the finally blocks may throw again, or cause more corruption, or delete something important from the disk or database). May I'm more confused than I realise, but I don't agree with some of that. Please would other folks comment. I understand that there are many low level Exceptions we don't want to swallow. My commonExceptionHandler() function could reasonably rethrow those. This seems consistent with this answer to a related question. Which does say "Depending on your context it can be acceptable to use catch(...), providing the exception is re-thrown." So I conclude using catch (Exception ) is not always evil, silently swallowing certain exceptions is. The phrase "Until .NET 4 it is very bad to Catch Exception" What changes in .NET 4? IS this a reference to AggregateException, which may give us some new things to do with exceptions we catch, but I don't think changes the fundamental "don't swallow" rule. The next phrase really bothers be. Can this be right? It also means that in the event of some kind of corruption that triggers such an exception, any open finally blocks on the stack will be executed (the finally blocks may throw again, or cause more corruption, or delete something important from the disk or database) My understanding is that if some low level code had lowLevelMethod() { try { lowestLevelMethod(); } finally { some really important stuff } } and in my code I call lowLevel(); try { lowLevel() } catch (Exception e) { exception handling and maybe rethrowing } Whether or not I catch Exception this has no effect whatever on the excution of the finally block. By the time we leave lowLevelMethod() the finally has already run. If the finally is going to do any of the bad things, such as corrupt my disk, then it will do so. My catching the Exception made no difference. If It reaches my Exception block I need to do the right thing, but I can't be the cause of dmis-executing finallys

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  • translating specifications into query predicates

    - by Jeroen
    I'm trying to find a nice and elegant way to query database content based on DDD "specifications". In domain driven design, a specification is used to check if some object, also known as the candidate, is compliant to a (domain specific) requirement. For example, the specification 'IsTaskDone' goes like: class IsTaskDone extends Specification<Task> { boolean isSatisfiedBy(Task candidate) { return candidate.isDone(); } } The above specification can be used for many purposes, e.g. it can be used to validate if a task has been completed, or to filter all completed tasks from a collection. However, I want to re-use this, nice, domain related specification to query on the database. Of course, the easiest solution would be to retrieve all entities of our desired type from the database, and filter that list in-memory by looping and removing non-matching entities. But clearly that would not be optimal for performance, especially when the entity count in our db increases. Proposal So my idea is to create a 'ConversionManager' that translates my specification into a persistence technique specific criteria, think of the JPA predicate class. The services looks as follows: public interface JpaSpecificationConversionManager { <T> Predicate getPredicateFor(Specification<T> specification, Root<T> root, CriteriaQuery<?> cq, CriteriaBuilder cb); JpaSpecificationConversionManager registerConverter(JpaSpecificationConverter<?, ?> converter); } By using our manager, the users can register their own conversion logic, isolating the domain related specification from persistence specific logic. To minimize the configuration of our manager, I want to use annotations on my converter classes, allowing the manager to automatically register those converters. JPA repository implementations could then use my manager, via dependency injection, to offer a find by specification method. Providing a find by specification should drastically reduce the number of methods on our repository interface. In theory, this all sounds decent, but I feel like I'm missing something critical. What do you guys think of my proposal, does it comply to the DDD way of thinking? Or is there already a framework that does something identical to what I just described?

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  • Gradual memory leak in loop over contents of QTMovie

    - by Benji XVI
    I have a simple foundation tool that exports every frame of a movie as a .tiff file. Here is the relevant code: NSString* movieLoc = [NSString stringWithCString:argv[1]]; QTMovie *sourceMovie = [QTMovie movieWithFile:movieLoc error:nil]; int i=0; while (QTTimeCompare([sourceMovie currentTime], [sourceMovie duration]) != NSOrderedSame) { // save image of movie to disk NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSString *filePath = [NSString stringWithFormat:@"/somelocation_%d.tiff", i++]; NSData *currentImageData = [[sourceMovie currentFrameImage] TIFFRepresentation]; [currentImageData writeToFile:filePath atomically:NO]; NSLog(@"%@", filePath); [sourceMovie stepForward]; [arp release]; } [pool drain]; return 0; As you can see, in order to prevent very large memory buildups with the various transparently-autoreleased variables in the loop, we create, and flush, an autoreleasepool with every run through the loop. However, over the course of stepping through a movie, the amount of memory used by the program still gradually increases. Instruments is not detecting any memory leaks per se, but the object trace shows certain General Data blocks to be increasing in size. [Edited out reference to slowdown as it doesn't seem to be as much of a problem as I thought.] Edit: let's knock out some parts of the code inside the loop & see what we find out... Test 1 while (banana) { NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSString *filePath = [NSString stringWithFormat:@"/somelocation_%d.tiff", i++]; NSLog(@"%@", filePath); [sourceMovie stepForward]; [arp release]; } Here we simply loop over the whole movie, creating the filename and logging it. Memory characteristics: remains at 15MB usage for the duration. Test 2 while (banana) { NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSImage *image = [sourceMovie currentFrameImage]; [sourceMovie stepForward]; [arp release]; } Here we add back in the creation of the NSImage from the current frame. Memory characteristics: gradually increasing memory usage. RSIZE is at 60MB by frame 200; 75MB by f300. Test 3 while (banana) { NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSImage *image = [sourceMovie currentFrameImage]; NSData *imageData = [image TIFFRepresentation]; [sourceMovie stepForward]; [arp release]; } We've added back in the creation of an NSData object from the NSImage. Memory characteristics: Memory usage is again increasing: 62MB at f200; 75MB at f300. In other words, largely identical. It looks like a memory leak in the underlying system QTMovie uses to do currentFrameImage, to me.

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  • How to obtain the first cluster of the directory's data in FAT using C# (or at least C++) and Win32A

    - by DarkWalker
    So I have a FAT drive, lets say H: and a directory 'work' (full path 'H:\work'). I need to get the NUMBER of the first cluster of that directory. The number of the first cluster is 2-bytes value, that is stored in the 26th and 27th bytes of the folder enty (wich is 32 bytes). Lets say I am doing it with file, NOT a directory. I can use code like this: static public string GetDirectoryPtr(string dir) { IntPtr ptr = CreateFile(@"H:\Work\dover.docx", GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, OPEN_EXISTING, 0,//FILE_FLAG_BACKUP_SEMANTICS, IntPtr.Zero); try { const uint bytesToRead = 2; byte[] readbuffer = new byte[bytesToRead]; if (ptr.ToInt32() == -1) return String.Format("Error: cannot open direcotory {0}", dir); if (SetFilePointer(ptr, 26, 0, 0) == -1) return String.Format("Error: unable to set file pointer on file {0}", ptr); uint read = 0; // real count of read bytes if (!ReadFile(ptr, readbuffer, bytesToRead, out read, 0)) return String.Format("cant read from file {0}. Error #{1}", ptr, Marshal.GetLastWin32Error()); int result = readbuffer[0] + 16 * 16 * readbuffer[1]; return result.ToString();//ASCIIEncoding.ASCII.GetString(readbuffer); } finally { CloseHandle(ptr); } } And it will return some number, like 19 (quite real to me, this is the only file on the disk). But I DONT need a file, I need a folder. So I am puttin FILE_FLAG_BACKUP_SEMANTICS param for CreateFile call... and dont know what to do next =) msdn is very clear on this issue http://msdn.microsoft.com/en-us/library/aa365258(v=VS.85).aspx It sounds to me like: "There is no way you can get a number of the folder's first cluster". The most desperate thing is that my tutor said smth like "You are going to obtain this or you wont pass this course". The true reason why he is so sure this is possible is because for 10 years (or may be more) he recieved the folder's first cluster number as a HASH of the folder's addres (and I was stupid enough to point this to him, so now I cant do it the same way) PS: This is the most spupid task I have ever had!!! This value is not really used anythere in program, it is only fcking pointless integer.

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  • Remove links with Javascript

    - by Arlen Beiler
    How do I remove links from a webpage with Javascript. I am using Google Chrome. The code I tried is: function removehyperlinks() { try { alert(document.anchors.length); alert(document.getElementsByTagName('a')); for(i=0;i=document.anchors.length;i++) { var a = document.anchors[i]; a.outerHTML = a.innerHTML; var b = document.getElementsByTagName('a'); b[i].outerHTML = b[i].innerHTML; } } catch(e) { alert (e);} alert('done'); } Of course, this is test code, which is why I have the alerts and 2 things trying at the same time. The first alert returns "0" the second [Object NodeList] and the third returns "done". My html body looks like this: <body onload="removehyperlinks()"> <ol style="text-align:left;" class="messagelist"> <li class="accesscode"><a href="#">General information, Updates, &amp; Meetings<span class="extnumber">141133#</span></a> <ol> <li><a href="#">...</a></li> <li><a href="#">...</a></li> <li><a href="#">...</a></li> <li><a href="#">...</a></li> <li><a href="#">...</a></li> <li><a href="#">...</a></li> <li><a href="#">...</a></li> <li><a href="#">...</a></li> <li start="77"><a href="#"">...</a></li> <li start="88"><a href="#">...</a></li> <li start="99"><a href="#">...</a></li> </ol> </li> </ol> </body>

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  • Why is this simple Mobile Form not closed when using the player

    - by ajhvdb
    Hi, I created this simple sample Form with the close button. Everything is working as expected when NOT using the Interop.WMPLib.dll I've seen other applications using this without problems but why isn't the Form process closed when I just add the line: SoundPlayer myPlayer = new SoundPlayer(); and of course dispose it: if (myPlayer != null) { myPlayer.Dispose(); myPlayer = null; } The Form closes but the debugger VS2008 is still active. The Form project and the dll are still active. If you send me an email to [email protected], I can send you the zipped project. Below is the class for the dll: using System; using System.Collections.Generic; using System.Text; using System.Threading; using System.Runtime.InteropServices; using WMPLib; namespace WindowsMobile.Utilities { public delegate void SoundPlayerStateChanged(SoundPlayer sender, SoundPlayerState newState); public enum SoundPlayerState { Stopped, Playing, Paused, } public class SoundPlayer : IDisposable { [DllImport("coredll")] public extern static int waveOutSetVolume(int hwo, uint dwVolume); [DllImport("coredll")] public extern static int waveOutGetVolume(int hwo, out uint dwVolume); WindowsMediaPlayer myPlayer = new WindowsMediaPlayer(); public SoundPlayer() { myPlayer.uiMode = "invisible"; myPlayer.settings.volume = 100; } string mySoundLocation = string.Empty; public string SoundLocation { get { return mySoundLocation; } set { mySoundLocation = value; } } public void Pause() { myPlayer.controls.pause(); } public void PlayLooping() { Stop(); myPlayer.URL = mySoundLocation; myPlayer.settings.setMode("loop", true); } public int Volume { get { return myPlayer.settings.volume; } set { myPlayer.settings.volume = value; } } public void Play() { Stop(); myPlayer.URL = mySoundLocation; myPlayer.controls.play(); } public void Stop() { myPlayer.controls.stop(); myPlayer.close(); } #region IDisposable Members public void Dispose() { try { Stop(); } catch (Exception) { } // need this otherwise the process won't exit?! try { int ret = Marshal.FinalReleaseComObject(myPlayer); } catch (Exception) { } myPlayer = null; GC.Collect(); } #endregion } }

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  • JAXB doesn't unmarshal list of interfaces

    - by Joker_vD
    It seems JAXB can't read what it writes. Consider the following code: interface IFoo { void jump(); } @XmlRootElement class Bar implements IFoo { @XmlElement public String y; public Bar() { y = ""; } public Bar(String y) { this.y = y; } @Override public void jump() { System.out.println(y); } } @XmlRootElement class Baz implements IFoo { @XmlElement public int x; public Baz() { x = 0; } public Baz(int x) { this.x = x; } @Override public void jump() { System.out.println(x); } } @XmlRootElement public class Holder { private List<IFoo> things; public Holder() { things = new ArrayList<>(); } @XmlElementWrapper @XmlAnyElement public List<IFoo> getThings() { return things; } public void addThing(IFoo thing) { things.add(thing); } } // ... try { JAXBContext context = JAXBContext.newInstance(Holder.class, Bar.class, Baz.class); Holder holder = new Holder(); holder.addThing(new Bar("1")); holder.addThing(new Baz(2)); holder.addThing(new Baz(3)); for (IFoo thing : holder.getThings()) { thing.jump(); } StringWriter s = new StringWriter(); context.createMarshaller().marshal(holder, s); String data = s.toString(); System.out.println(data); StringReader t = new StringReader(data); Holder holder2 = (Holder)context.createUnmarshaller().unmarshal(t); for (IFoo thing : holder2.getThings()) { thing.jump(); } } catch (Exception e) { System.err.println(e.getMessage()); } It's a simplified example, of course. The point is that I have to store two very differently implemented classes, Bar and Baz, in one collection. Well, I observed that they have pretty similar public interface, so I created an interface IFoo and made them two to implement it. Now, I want to have tools to save and load this collection to/from XML. Unfortunately, this code doesn't quite work: the collection is saved, but then it cannot be loaded! The intended output is 1 2 3 some xml 1 2 3 But unfortunately, the actual output is 1 2 3 some xml com.sun.org.apache.xerces.internal.dom.ElementNSImpl cannot be cast to testapplication1.IFoo Apparently, I need to use the annotations in a different way? Or to give up on JAXB and look for something else? I, well, can write "XMLNode toXML()" method for all classes I wan't to (de)marshal, but...

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  • What would you suggest as a high school first language?

    - by ldigas
    Edit by OA: After reading some answers I'll just update the question a little. At first I put it a little bluntly, but some of those gave me some good arguments which have to be taken into consideration while making a stand on this one. (these are mostly picked up from comments and answers below). A few things to take into account: to many pupils this is a first programming language - at this stage most of them have trouble grasping a difference between data types, variable passing, ... and whatnot, less alone pointers and similar 'low level stuff' :) they will all have to pass this to get into next grade (well, big majority of them anyway) not all of them have computers at home, not all of them are willing to learn this, less alone interested in - so the concepts have to be taught on a finite time scale in school hours (as well as practice on computers) free literature is a bonus - the teacher will make some scripts and handaways, but still ... I wouldn't like to bear the parents with the burden of buying expensive literature (also, english is not a native language here ... and although they are all learning it, their ability to read it fluently is somewhat questionable) somebody gave an argument - "a language which does not get in the way of ideas" - good one accessibility on different platforms in not expecially important at this point - although most of the suggested ones are available on win as well as linux - not many macs in this part of europe (their prices are sky high for anything but specialised usage) I will check what are the licencing issues on ms express editions about using it massively in high schools for purposes like this - if someone has any info about this, please, do not be shy with it :) A friend of mine, informatics teacher - in EU it comes as something as junior cs teacher, in a local high school asked me what I thought about what should be the first language pupils should be taught? It is a technical school (a little more oriented towards mathematics than the gymnasium, but not computer oriented totally). So I'm asking you - what do you think should be the first language pupils are exposed to in highschool? They have been teaching Pascal so far, but she's not sure that's a good course. She thought about switching to C (which I resented; considering not all pupils have interests in programming, to start with, and should be taught something higher level since they are just gripping the idea of a loop and such ... for a start), I suggested python or ruby (preferably py since it handles all paradigms). What is your opinion on this one? I looked, but didn't find a similar question on SO, so if there is one, please just point me towards it. Edit: The assumption is that none of the pupils have been exposed to any programming in junior school. See also: What is the best way to teach young kids some basic programming concepts? Best ways to teach a beginner to program How and when do you teach a kid to code What is the easiest language to start with? High School Programming

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  • Separate specific #ifdef branches

    - by detly
    In short: I want to generate two different source trees from the current one, based only on one preprocessor macro being defined and another being undefined, with no other changes to the source. If you are interested, here is my story... In the beginning, my code was clean. Then we made a new product, and yea, it was better. But the code saw only the same peripheral devices, so we could keep the same code. Well, almost. There was one little condition that needed to be changed, so I added: #if defined(PRODUCT_A) condition = checkCat(); #elif defined(PRODUCT_B) condition = checkCat() && checkHat(); #endif ...to one and only one source file. In the general all-source-files-include-this header file, I had: #if !(defined(PRODUCT_A)||defined(PRODUCT_B)) #error "Don't make me replace you with a small shell script. RTFM." #endif ...so that people couldn't compile it unless they explicitly defined a product type. All was well. Oh... except that modifications were made, components changed, and since the new hardware worked better we could significantly re-write the control systems. Now when I look upon the face of the code, there are more than 60 separate areas delineated by either: #ifdef PRODUCT_A ... #else ... #endif ...or the same, but for PRODUCT_B. Or even: #if defined(PRODUCT_A) ... #elif defined(PRODUCT_B) ... #endif And of course, sometimes sanity took a longer holiday and: #ifdef PRODUCT_A ... #endif #ifdef PRODUCT_B ... #endif These conditions wrap anywhere from one to two hundred lines (you'd think that the last one could be done by switching header files, but the function names need to be the same). This is insane. I would be better off maintaining two separate product-based branches in the source repo and porting any common changes. I realise this now. Is there something that can generate the two different source trees I need, based only on PRODUCT_A being defined and PRODUCT_B being undefined (and vice-versa), without touching anything else (ie. no header inclusion, no macro expansion, etc)?

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  • dynamically embedding youtube videos with jquery

    - by danwoods
    Hello all, I'm trying to retrieve a listing of a user's youtube videos and embed them in a page using jQuery. My code looks something like this: $(document).ready(function() { //some variables var fl_obj_template = $('<object width="260" height="140">' + '<param name="movie" value=""></param>' + '<param name="allowFullScreen" value="true"></param>' + '<param name="allowscriptaccess" value="always"></param>' + '<embed src="" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="260" height="140"></embed>' + '</object>'); var video_elm_arr = $('.video'); //hide videos until ready $('.video').addClass('hidden'); //pull video data from youtube $.ajax({ url: 'http://gdata.youtube.com/feeds/api/users/username/uploads?alt=json', dataType: 'jsonp', success: function(data) { $.each(data.feed.entry, function(i,item){ //only take the first 7 videos if(i > 6) return; //give the video element a flash object var cur_flash_obj = fl_obj_template; //assign title $(video_elm_arr[i]).find('.video_title').html(item.title.$t); //clean url var video_url = item.media$group.media$content[0].url; var index = video_url.indexOf("?"); if (index > 0) video_url = video_url.substring(0, index); //and asign it to the player's parameters $(cur_flash_obj).find('object param[name="movie"]').attr('value', video_url); $(cur_flash_obj).find('object embed').attr('src', video_url); //alert(cur_flash_obj); //insert flash object in video element $(video_elm_arr[i]).append(cur_flash_obj); //and show $(video_elm_arr[i]).removeClass('hidden'); }); } }); }); (of course with 'username' being the actual username). The video titles appear correctly but no videos show up. What gives? The target html looks like: <div id="top_row_center" class="video_center video"> <p class="video_title"></p> </div>

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  • Strange problem publishing a fresh Ruby on Rails 3 application on localhost (Apache, Passenger and VirtualHosts)

    - by user502052
    I recently created a new Ruby on Rails 3 application locally on a Mac OS, named "test". Since I use apache2, in the private/etc/apache2/httpd.conf I set the VirtualHost for the "test" application: <VirtualHost *:443> ServerName test.pjtmain.localhost:443 DocumentRoot "/Users/<my_user_name>/Sites/test/public" RackEnv development <Directory "/Users/<my_user_name>/Sites/test/public"> Order allow,deny Allow from all </Directory> # SSL Configuration SSLEngine on ... </VirtualHost> <VirtualHost *:80> ServerName test.pjtmain.localhost DocumentRoot "/Users/<my_user_name>/Sites/test/public" RackEnv development <Directory "/Users/<my_user_name>/Sites/test/public"> Order allow,deny Allow from all </Directory> </VirtualHost> Of course I restart apache2, but trying to access to http://test.pjtmain.localhost/ I have this error message from: FIREFOX Oops! Firefox could not find test.pjtmain.localhost Suggestions: * Search on Google: ... SAFARI Safari can’t find the server. Safari can’t open the page “http://test.pjtmain.localhost/” because Safari can’t find the server “test.pjtmain.localhost”. I have other RoR3 applications setted like that above in the httpd.conf file and all them work. What is the problem (maybe it is not related to apache...)? Notes: 1. Using the 'Network Uility' I did a Ping with the following result: ping: cannot resolve test.pjtmain.localhost: Unknown host and I did a Lookup with the follonwing result: ; <<>> DiG 9.6.0-APPLE-P2 <<>> test.pjtmain.localhost +multiline +nocomments +nocmd +noquestion +nostats +search ;; global options: +cmd <MY_BROADBAND_TELECOMUNICATIONS_COMPANY_NAME>.com. 115 IN SOA dns1.<MY_BROADBAND_TELECOMUNICATIONS_COMPANY_NAME>.com. dnsmaster.<MY_BROADBAND_TELECOMUNICATIONS_COMPANY_NAME>.com. ( 2010110500 ; serial 10800 ; refresh (3 hours) 900 ; retry (15 minutes) 604800 ; expire (1 week) 86400 ; minimum (1 day) ) 2. I am using Phusion Passenger 3. Since I not changed nothing to the new "test" application, I expect to see the default RoR index.html page: 4. It seems that in the 'Console Messages' there is any warning or error

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