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  • Some basic UML questions

    - by devoured elysium
    What does it mean when you have something as the following picture? Each Customer has none, one or more Orders while each Order has only one Customer? And in relationship to the following one: What does the black diamond mean in this context? How is that black diamond called? Thanks

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  • questions on nfa and dfa..

    - by Loop
    Hi Guys... Hope you help me with this one.... I have a main question which is ''how to judge whether a regular expression will be accepted by NFA and/or DFA? For eg. My question says that which of the regular expressions are equivalent? explain... 1.(a+b)*b(a+b)*b(a+b)* 2.a*ba*ba* 3.a*ba*b(a+b)* do we have to draw the NFA and DFA and then find through minimisation algorithm? if we do then how do we come to know that which regular expression is accepted by NFA/DFA so that we can begin with the answer? its so confusing.... Second is a very similar one, the question asks me to show that the language (a^nb^n|n1} is not accepted by DFA...grrrrr...how do i know this? (BTW this is a set of all strings of where a number of a's is followed by the same number of b's).... I hope I explained clearly well....

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  • emacs -- keybind questions

    - by user565739
    I have successfully used Ctrl+Shift+Up ' Ctrl+Shift+down ' Ctrl+Shift+left' Ctrl+Shift+Right to different commands. But when I tried to use Ctrl+s to the command save-buffer and Ctrl+Shift+s, which is equivalent to Ctrl+S, to another command, it has some problem. save-buffer works fine, but when I type Ctrl+Shift+s, it excute the command save-buffer. I used Ctrl+q to find the control sequences of Ctrl+s and Ctrl+Shift+S, I get the same result, which is ^S. I expect that I will get ^s for Ctrl+s, but it doesn't. Anyone knows the reason? Another queston is: I use Ctrl+c for the command killing-ring-save. In this case, all commands (which are of large number) begin with Ctrl+c don't work now. Is there a way to replace the prefix Ctrl+c by another customized prefix? I may pose my question in the wrong direction. I use ctrl+c as killing-ring-save. It works fine in emacs (no mode). But if I open a .c file (C-mode), then when I type Ctrl+c, it waits me to type another key. I think in this case, ctrl+c is regarded as a prefix. In this case, I need the following modifications: Using a custom defined prefix, say Ctrl+a, as Ctrl+c ; Remove the prefix Ctrl+c ; Using Ctrl+c as killing-ring-save. I add the following to my ~/.emacs : (defun my-c-initialization-hook () (define-key c-mode-base-map (kbd "C-a") mode-specific-map) (define-key c-mode-base-map (kbd "C-c") 'kill-ring-save)) (add-hook 'c-initialization-hook 'my-c-initialization-hook) But this doesn't work. Ctrl+c is still regarded as a prefix, so I can't use it as kill-ring-save. Furthermore, if I type Ctrl+a Ctrl+c, it said it's not defined. (I thought it will have the same result as I type Ctrl+c Ctrl+c)

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  • Two questions on ensuring EndInvoke() gets called on a list of IAsyncResult objects

    - by RobV
    So this question is regarding the .Net IAsyncResult design pattern and the necessity of calling EndInvoke as covered in this question Background I have some code where I'm firing off potentially many asynchronous calls to a particular function and then waiting for all these calls to finish before using EndInvoke() to get back all the results. Question 1 I don't know whether any of the calls has encountered an exception until I call EndInvoke() and in the event that an exception occurs in one of the calls the entire method should fail and the exception gets wrapped into an API specific exception and thrown upwards. So my first question is what's the best way then to ensure that the remainder of the async calls get properly terminated? Is a finally block which calls EndInvoke() on the remainder of the unterminated calls (and ignores any further exceptions) the best way to do this? Question 2 Secondly when I first fire off all my asyc calls I then call WaitHandle.WaitAll() on the array of WaitHandle instances that I've got from my IAsyncResult instances. The method which is firing all these async calls has a timeout to adhere to so I provide this to the WaitAll() method. Then I test whether all the calls have completed, if not then the timeout must have been reached so the method should also fail and throw another API specific exception. So my second question is what should I do in this case? I need to call EndInvoke() to terminate all these async calls before I throw the error but at the same time I don't want the code to get stuck since EndInvoke() is blocking. In theory at least if the WaitAll() call times out then all the async calls should themselves have timed out and thrown exceptions (thus completing the call) since they are also governed by a timeout but this timeout is potentially different from the main timeout

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  • Some questions about working with Haml

    - by damian
    I am trying to use Haml with Grails but I am having some issues. The plugin for haml has errors to parse empty lines. The plugin generate gsp files, so I think that I can use the online haml html generator. Bug I want something like an editor with syntax highlithing, blocks, etc, and that generate html. Is there something like this? Or only the editor? thanks in advance

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  • Questions about serving static files from a servlet

    - by Geo
    I'm very new to servlets. I'd like to serve some static files, some css and some javascript. Here's what I got so far: in web.xml: <servlet> <description></description> <display-name>StaticServlet</display-name> <servlet-name>StaticServlet</servlet-name> <servlet-class>StaticServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>StaticServlet</servlet-name> <url-pattern>/static/*</url-pattern> </servlet-mapping> I'm assuming in the StaticServlet I'd have to work with request.getPathInfo to see what was requested, get a mime type, read the file & write it to the client. If this is not the way to go, or is not a viable way of doing things, please suggest a better way. I'm not really sure where to place the static directory, because if I try to print new File(".") it gives me the directory of my Eclipse installation. Is there a way to find out the project's directory?

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  • Hardware-specific questions

    - by overflow
    I'm good at programming yet I feel like I don't know enough about the architecture of the hardware I'm working on. What does the Northbridge on the mainboard do? What does the L2 cache of my processor do? Can Windows XP use multiple processors? Not in terms of concrete multitasking in all programs but using the capacity of all cores if needed instead of always only one core. How can my processor/mainboard interact with multiple kinds of graphics/sound cards?

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  • Java EE Website Planning Questions

    - by Tom Tresansky
    I'm a .NET programming who is soon moving to the Java EE world. I have plenty of experience with .NET web technologies, web services, WebForms and MVC. I am also very familiar with the Java language, and have written a few servlets and modified a couple of JSP pages, but I haven't touched EE yet. I'd like to set up a public website using Java EE so I can familiarize myself with whats current. I'm thinking just a technology playground at this point with no particular purpose in mind. What Java technologies are the current hotness for this sort of thing? (For example, if someone asked me what I'd recommend learning to set up a new .NET site, I'd say use ASP MVC instead of WebForms and recommend LINQ-to-SQL as a quick, simple and widely used ORM.) So, what I'd like to know is: Is there a recommended technology for the presentation layer? Is JSP considered a good approach, or is there anything cleaner/newer/more widespread? Is Hibernate still widely used for persistence? Is it obsolete? Is there anything better out there? (I've worked with NHibernate some, so I wouldn't be starting from scratch.) Is cheap Java EE web hosting available? What should I know being a .NET web developer moving to the Java world?

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  • Django Development Environment Setup Questions

    - by Ross Peoples
    Hello, I'm trying to set up a good development environment for a Django project that I will be working on from two different physical locations. I have two Mac machines, one at home and one at work that I do most of my development on. I currently host a Ubuntu virtual machine on one of the machines to host the Django environemnt, install DropBox on it, and edit source code from my Mac. When I save the code file, the changes get synced over DropBox to the Ubuntu VM and the Django development server automatically restarts because of the change. This method has worked well in the past, but I am starting to use DropBox for a lot of other things now and don't want all of that to be downloaded on every virtual machine I use. Plus, I want to start using Eclipse + PyDev to be able to debug code and have code completion. Currently, I use TextEdit which is great, but doesn't support debugging or completion. So what are my options? I thought about setting up a Parallels VM on a thumb drive that has my entire environment on it (Eclipse included), but that has its own problems. Any other thoughts?

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  • PHP Sessions - Locking and Sharing questions

    - by Nuno Peralta
    Hi, I would like to know if it is possible to read $_SESSION attributes without locking it. Currently, session_start() locks SESSION, that means other PHP processes will wait until it is unlocked. But, some processes just want to get some $_SESSION variables, not to write on them. Is that possible to implement some function like session_get(string $id) which doesn't lock SESSION? Also, it is possible to share SESSIONs between browsers, once the user is logged in the same account, for example, using session_id('shared_vars_of_'.$userid). But, is that secure? Is this discouraged? Thanks, Nuno

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  • Memory Profiling with DotTrace Questions

    - by cam
    I ran dotTrace on my application (which is having some issues). IntPtr System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr, IntPtr, Int32, IntPtr, IntPtr) Void System.Windows.Forms.UnsafeNativeMethods.WaitMessage() Are the two main functions that came up, taking about 94% of the application time. Since I didn't know what these two functions were, I ran through my code line by line. It runs smooth and efficiently until a point where it just hangs. "newFrm.Show()". The newFrm only contains a textbox. The larger the file I load into the text box (it's a notepad program), the longer it takes. Now normally this makes sense, but it takes about 30 seconds for a 167 kB file. Now I'm not sure what to do. It runs incredibly slow/stops functioning when you load a textfile and try to resize the window containing the text file too. Then I realized that it is only struggling to open text files with a long string of hex inside (ie) "XX-XX-XX-" etc. With other similarly sized files it struggles with resizing somewhat, but opens within a couple seconds. Does this have something to do with the textbox properties? I've set it to multiline and set maximum characters to 0 (so unlimited). How do I solve this issue? Is there some way I can see what is being called in those functions?

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  • simple php Dollar $ evaluation in string questions

    - by Mirage
    I have always been confused that .e,g in php i have sql statement $qry = "select * from table where id = $id"; now can i insert "$" directly inside the quotes or i have to use $qry = "select * from table where id =".$id." "; or $qry = 'select * from table where id = $id'; or $qry = 'select * from table where id = '$id''; Which is correct

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  • Few iPhone noob questions

    - by mshsayem
    Why should I declare local variables as 'static' inside a method? Like: static NSString *cellIdentifier = @"Cell"; Is it a performance advantage? (I know what 'static' does; in C context) What does this syntax mean?[someObj release], someObj = nil; Two statements? Why should I assign nil again? Is not 'release' enough? Should I do it for all objects I allocate/own? Or for just view objects? Why does everyone copy NSString, but retains other objects (in property declaration)? Yes, NSStrings can be changed, but other objects can be changed also, right? Then why 'copy' for just NSString, not for all? Is it just a defensive convention? Shouldn't I release constant NSString? Like here:NSString *CellIdentifier = @"Cell"; Why not? Does the compiler allocate/deallocate it for me? In some tutorial application I observed these (Built with IB): Properties(IBOutlet, with same ivar name): window, someLabel, someTextField, etc etc... In the dealloc method, although the window ivar was released, others were not. My question is: WHY? Shouldn't I release other ivars(labels, textField) as well? Why not? Say, I have 3 cascaded drop-down lists. I mean, based on what is selected on the first list, 2nd list is populated and based on what is selected on the second list, 3rd list is populated. What UI components can reflect this best? How is drop-down list presented in iPhone UI? Tableview with UIPicker? When should I update the 2nd, 3rd list? Or just three labels which have touch events? Can you give me some good example tutorials about Core-Data? (Not just simple data fetching and storing on 2/3 tables with 1/2 relationship) How can I know whether my app is leaking memory? Any tools?

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  • Few Basic Questions in Overriding

    - by Dahlia
    I have few problems with my basic and would be thankful if someone can clear this. What does it mean when I say base *b = new derived; Why would one go for this? We very well separately can create objects for class base and class derived and then call the functions accordingly. I know that this base *b = new derived; is called as Object Slicing but why and when would one go for this? I know why it is not advisable to convert the base class object to derived class object (because base class is not aware of the derived class members and methods). I even read in other StackOverflow threads that if this is gonna be the case then we have to change/re-visit our design. I understand all that, however, I am just curious, Is there any way to do this? class base { public: void f(){cout << "In Base";} }; class derived:public base { public: void f(){cout << "In Derived";} }; int _tmain(int argc, _TCHAR* argv[]) { base b1, b2; derived d1, d2; b2 = d1; d2 = reinterpret_cast<derived*>(b1); //gives error C2440 b1.f(); // Prints In Base d1.f(); // Prints In Derived b2.f(); // Prints In Base d1.base::f(); //Prints In Base d2.f(); getch(); return 0; } In case of my above example, is there any way I could call the base class f() using derived class object? I used d1.base()::f() I just want to know if there any way without using scope resolution operator? Thanks a lot for your time in helping me out!

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  • Custom Swing component: questions on approach

    - by phatmanace
    Hi Folks, I'm trying to build a new java swing component, I realise that I might be able to find one that does what I need on the web, but this is partly an exercise for me to learn ow to do this. I want to build a swing component that represents a Gantt chart. it would be good (though not essential for people to be able to interact with it (e.g slide the the tasks around to adjust timings) it feels like the best approach for this is to subclass JComponent, and override PaintComponent() to 'draw a picture' of what the chart should look like, as opposed to doing something like trying to jam everything into a custom JTable. I've read a couple of books on the subject, and also looked at a few examples (most notably things like JXGraph) - but I'm curious about a few things When do I have to switch to using UI delegates, and when can I stick to just fiddling around in paintcomponent() to render what I want? if I want other swing components as sub-elements of my component (e.g I wanted a text box on my gantt chart) can I no longer use paintComponent()? can I arbitrarily position them within my Gantt chart, or do I have to use a normal swing layout manager many thanks in advance. -Ace

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  • Using a "take-home" coding component in interview process

    - by Jeff Sargent
    In recent interviews I have been asking candidates to code through some questions on the whiteboard. I don't feel I'm getting a clear enough picture of the candidates technical ability with this approach. Granted, the questions might not be good enough, maybe the interview needs to be longer, etc, but I'm wondering if a different approach would be better. What I'd like to try is to create a simple, working project in Visual Studio and have it checked into source control. The candidate can check that code out from home/wherever and then check back in work representing their response to the assignment that I'll provide. I'm thinking that if the window of time is short enough and the assignment clear enough then the solution will be safe enough from all-out Googling (i.e. they couldn't search for and find the entire solution online). I would then be able to review the candidates work. Has enough worked with something like this before, either to vet a candidate or as a candidate yourself? Any thoughts in general? P.S. my first StackOverflow question - hi guys and gals. EDIT: I've seen comments about asking someone to work for free - I wouldn't mind paying the person for their time.

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  • Ubuntu terminal questions

    - by Camran
    I am wondering about my VPS providers ubuntu terminal. Are all these terminals the same? I think they are so user-UN-friendly. I can't copy-paste into the terminal, when I try opening textfiles, I can't scroll up and down easily. I cant save easily. Nothing is easy... Is it always like this with Ubuntu? Is there any way to make it easier? I use windows but I login to my vps provider with login details and then simply click "terminal" to open the terminal. Please help me out here

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  • Flex noob questions

    - by Jerry
    Hi all I was wondering how to copy files (like my images files) into my flex 4 src folder from windows explorer. There is no such folder called src when I look at my project folder. Thanks.

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  • Questions about .NET CollectionEditor type

    - by smwikipedia
    Who can tell me the internal working mechanism of a CollectionEditor in plain English? I have implemented every virtual function and step into each of them. Still got no clue of its intended algorithm. I searched the web and found tons of compaints about the CollectionEditor type, and even bugs. I am kind of thinking of the CollectionEditor as a total mess.

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  • How to track the answers in quiz of camtasia product?

    - by Srikanth
    I am using camtasia product. I have created a video and added quizzing along with the video and produced it. I got flash output. I opened it in the browser and played the video. In the quiz section I have entered the answers. Now my question is how to retrieve these answers??. Where these answers will be stored?

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  • Questions about using git as a backend storage system

    - by XO
    New to git here... I want to commit my personal file share to a git repo (text, docs, images etc). As I make modifications to various files over time, telling git about them along the way, how do go about things so I can: Get out of the business of traditional fulls/incrementals. Be able to do a point-in-time file or full clone restore. Basically, I want something granular, such that, if I make an edit to a file 5 times on a particular day. I will have 5 versions of that file that I can refer back to- forever. Or even just derive the a full copy of everything the way it looked on that particular day. I am currently using rsync for remote incremental syncs (no file versioning).

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  • Java Simple ActionListener Questions

    - by Allen
    I have a main class in a program that launches another class that handles all the GUI stuff. In the GUI, i have a button that i need to attach an ActionListener to. The only problem is, the code to be executed needs to reside within the main class. How can i get the ActionPerformed() method to execute in the main class when a button is clicked elsewhere?

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  • BasicDBObject or QueryBuilder and some newbie questions of Java and mongo

    - by Kevin Xu
    hi I'm a fresh newbie to mongodb Q1 using query=new BasicDBObject(); query.put("i", new BasicDBObject("$gt",13)); and query=new QueryBuilder().put("i").Greaterthan(13).get() is there any difference inside of the system? Q2 I've created a class class findkv extends BasicDBObject{ //is gt gte lt lte public findkv(String fieldname,String op,Object tvalue) { if (op=="") this.put(fieldname,tvalue); else this.put(fieldname, new BasicDBObject(op,tvalue)); } } shall I use it or shall I just use original function? Q3 I've used mongo shell for a few weeks, and was customed to it, and find writing in mongo shell faster and shorter, which side has more advantage, writing in mongo or in java? I shall dump them from mongo to mysql Q4 I've an if (statement==true) return else dowhat; seems can't be compiled I know I can write if (statement!=true) dowhat else return, but can I still write in first style? q5 my eclipse is Eclipse Java EE IDE for Web Developers. Version: Juno Release Build id: 20120614-1722 I'd like to install Perl which I haven't learned yet I choose Install Update http://e-p-i-c.sf.net/updates/testing but it doesn't work, any method to install perl to eclipse manually?

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  • C++ Header file questions

    - by Karl
    So I'm trying to learn C++ and I've gotten as far as using header files. They really make no sense to me. I've tried many combinations of this but nothing so far has worked: Main.cpp: #include "test.h" int main() { testClass Player1; return 0; } test.h: #ifndef TEST_H_INCLUDED #define TEST_H_INCLUDED class testClass { private: int health; public: testClass(); ~testClass(); int getHealth(); void setHealth(int inH); }; #endif // TEST_H_INCLUDED test.cpp: #include "test.h" testClass::testClass() { health = 100; } testClass::~testClass() {} int testClass::getHealth() { return(health); } void testClass::setHealth(int inH) { health = inH; } What I'm trying to do is pretty simple, but the way the header files work just makes no sense to me at all. Code blocks returns the following on build: obj\Debug\main.o(.text+0x131)||In function main':| *voip*\test\main.cpp |6|undefined reference totestClass::testClass()'| obj\Debug\main.o(.text+0x13c):voip\test\main.cpp|7|undefined reference to `testClass::~testClass()'| ||=== Build finished: 2 errors, 0 warnings ===| I'd appreciate any help. Or if you have a decent tutorial for it, that would be fine too (most of the tutorials I've googled haven't helped)

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