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  • Linux: How to find all serial devices (ttyS, ttyUSB and others)?

    - by Thomas Tempelmann
    What is the proper way to get a list of all available serial ports/devices on a Linux system? In other words, when I iterate over all devices in /dev/, how do I tell which ones are serial ports in the classic way, i.e. those usually supporting baud rates and RTS/CTS flow control? The solution would be coded in C. I ask because I am using a 3rd party library that does this clearly wrong: It appears to only iterate over /dev/ttyS*. The problem is that there are, for instance, serial ports over USB (provided by USB-RS232 adapters), and those are listed under /dev/ttyUSB*. And reading the Serial-HOWTO at Linux.org, I get the idea that there'll be other name spaces as well, as time comes. So I need to find the official way to detect serial devices. Problem is that there appears none documented, or I can't find it. I imagine one way would be to open all files from /dev/tty* and call a specific ioctl() on them that is only available on serial devices. Would that be a good solution, though?

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  • Lightweight spinlocks built from GCC atomic operations?

    - by Thomas
    I'd like to minimize synchronization and write lock-free code when possible in a project of mine. When absolutely necessary I'd love to substitute light-weight spinlocks built from atomic operations for pthread and win32 mutex locks. My understanding is that these are system calls underneath and could cause a context switch (which may be unnecessary for very quick critical sections where simply spinning a few times would be preferable). The atomic operations I'm referring to are well documented here: http://gcc.gnu.org/onlinedocs/gcc-4.4.1/gcc/Atomic-Builtins.html Here is an example to illustrate what I'm talking about. Imagine a RB-tree with multiple readers and writers possible. RBTree::exists() is read-only and thread safe, RBTree::insert() would require exclusive access by a single writer (and no readers) to be safe. Some code: class IntSetTest { private: unsigned short lock; RBTree<int>* myset; public: // ... void add_number(int n) { // Aquire once locked==false (atomic) while (__sync_bool_compare_and_swap(&lock, 0, 0xffff) == false); // Perform a thread-unsafe operation on the set myset->insert(n); // Unlock (atomic) __sync_bool_compare_and_swap(&lock, 0xffff, 0); } bool check_number(int n) { // Increment once the lock is below 0xffff u16 savedlock = lock; while (savedlock == 0xffff || __sync_bool_compare_and_swap(&lock, savedlock, savedlock+1) == false) savedlock = lock; // Perform read-only operation bool exists = tree->exists(n); // Decrement savedlock = lock; while (__sync_bool_compare_and_swap(&lock, savedlock, savedlock-1) == false) savedlock = lock; return exists; } }; (lets assume it need not be exception-safe) Is this code indeed thread-safe? Are there any pros/cons to this idea? Any advice? Is the use of spinlocks like this a bad idea if the threads are not truly concurrent? Thanks in advance. ;)

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  • Requiring library consumers reference additional assembly when using certain types

    - by Thomas G. Mayfield
    I have library code that uses ICSharpCode.SharpZipLib under the hood to make it easy to use ZIP files as data sources when running integration tests. As it stands, if I reference my library from another project, the other project will compile just fine, but when it accesses the code that uses SharpZipLib, I get an exception for it not finding the zip library: failed: System.IO.FileNotFoundException : Could not load file or assembly 'ICSharpCode.SharpZipLib, Version=0.85.5.452, Culture=neutral, PublicKeyToken=1b03e6acf1164f73' or one of its dependencies. The system cannot find the file specified. If the types in my library derived from a class in SharpZipLib, it'd generate a compile error CS0012. What other ways are there for triggering a CS0012, so that using code that requires SharpZipLib (but doesn't clearly indicate it) would cause consumer code to fail compilation? I've had similar problems in the past when I've used libraries like DeftTech.DuckTyping under the hood. I'd add my library code to a new project, start working, compile, run, and then suddenly hit an edge case that I'd used duck typing to get around and get a runtime error. What I'd most like is to have the same behavior as if I'd derived from a type in the 3rd-party library, so that a reference to my derived type generates a CS0012: The type 'type' is defined in an assembly that is not referenced. You must add a reference to assembly 'assembly'.

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  • Why does Clojure hang after hacing performed my calculations?

    - by Thomas
    Hi all, I'm experimenting with filtering through elements in parallel. For each element, I need to perform a distance calculation to see if it is close enough to a target point. Never mind that data structures already exist for doing this, I'm just doing initial experiments for now. Anyway, I wanted to run some very basic experiments where I generate random vectors and filter them. Here's my implementation that does all of this (defn pfilter [pred coll] (map second (filter first (pmap (fn [item] [(pred item) item]) coll)))) (defn random-n-vector [n] (take n (repeatedly rand))) (defn distance [u v] (Math/sqrt (reduce + (map #(Math/pow (- %1 %2) 2) u v)))) (defn -main [& args] (let [[n-str vectors-str threshold-str] args n (Integer/parseInt n-str) vectors (Integer/parseInt vectors-str) threshold (Double/parseDouble threshold-str) random-vector (partial random-n-vector n) u (random-vector)] (time (println n vectors (count (pfilter (fn [v] (< (distance u v) threshold)) (take vectors (repeatedly random-vector)))))))) The code executes and returns what I expect, that is the parameter n (length of vectors), vectors (the number of vectors) and the number of vectors that are closer than a threshold to the target vector. What I don't understand is why the programs hangs for an additional minute before terminating. Here is the output of a run which demonstrates the error $ time lein run 10 100000 1.0 [null] 10 100000 12283 [null] "Elapsed time: 3300.856 msecs" real 1m6.336s user 0m7.204s sys 0m1.495s Any comments on how to filter in parallel in general are also more than welcome, as I haven't yet confirmed that pfilter actually works.

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  • Could an ontology suitably replace an RDBMS for a web app?

    - by Thomas
    I'm considering storing the content of a web app in an RDF or OWL ontology instead of an RDBMS. However, when I research ontologies they seem to always exist in the context of publicly accessible data stores serving as the backbone of the semantic web. I've never heard of them being used as the content engine behind a web app. Is it reasonable to use an ontology instead of an RDBMS for such an application? (Again, this is just for content. User data, commerce and stuff like that will stay in a database as I see no need to reinvent the wheel there.)

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  • how to redirect terminal contents to a jtextpane?

    - by sonu thomas
    hi.. I was trying to run a java class file using java code.The aim was to direct the executing sequence of the terminal of fedora 10 into a frame with a textpane. My code is: import java.io.DataInputStream; import java.io.IOException; import javax.swing.JDialog; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JTextArea; import javax.swing.JTextPane; //import sun.reflect.ReflectionFactory.GetReflectionFactoryAction; public class file { /** * @param args */ /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException{ // TODO Auto-generated method stub JDialog jj = new JDialog(); jj.setTitle("helllo"); String sssub1,sssub2,sssub3; String ss="C:/Users/sonu/Desktop/ourIDE/src/src/nn.java"; JPanel n = new JPanel(); jj.setContentPane(n); JTextPane tpn2=new JTextPane(); jj.getContentPane().add(tpn2); jj.setVisible(true); Runtime runtime; Process process; if(ss.indexOf(" ")==-1) { try { runtime= Runtime.getRuntime(); sssub1="/home/ss/Desktop/src/"; sssub2="nn"; process=runtime.exec("sh jrun.sh "+sssub1+" "+sssub2); DataInputStream data=new DataInputStream(process.getInputStream()); DataInputStream data_data=new DataInputStream(process.getErrorStream()); String s="",t=""; int ch; while((ch=data.read())!=-1){ s=s+(char)ch; } data.close(); while((ch=data_data.read())!=-1){ t=t+(char)ch; } data_data.close(); if(t.equals("")) { s+="\nNormal Termination."; tpn2.setText(s); } else tpn2.setText(t); }catch(Exception e){ System.out.println("Error executing file==>"+e);} } } } The content of **jrun.sh** is cd $1 java $2 When the content of **nn.java** was this: import java.io.*; class nn { public static void main(String[] ar)throws IOException { int i=90; BufferedReader dt = new BufferedReader(new InputStreamReader(System.in)); System.out.println("Enter"); //i=Integer.parseInt(dt.readLine()); line--notable System.out.println("i="+i); } } It worked smoothly But when I remove the comment on line--notable,it gave me Textpane with no content. The problem is : I cant read an input from nn.java Kindly give me a solution... If i am able to: get the terminal pop up with executing the nn.class,and i am able to enter the input,then it will do... Thanks in advance...

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  • Can I check wheter Linq 2 SQL's DataContext is tracking entities?

    - by Thomas Jespersen
    We want to throw an exception, if a user calls DataContext.SubmitChanges() and the DataContext is not tracking anything. That is... it is OK to call SubmitChanges if there are no inserts, updates or deletes. But we want to ensure that the developer didn't forget to attach the entity to the DataContext. Even better... is it possible to get a collection of all entities that the DataContext is tracking (including those that are not changed)? PS: The last question I asked were answered with: "do it this way instead"... please don't :-)

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  • How do I localize the jQuery DatePicker?

    - by Thomas Eyde
    I really need a localized dropdown calendar. An English calendar doesn't exactly communicate excellence on a Norwegian website ;-) I have experimented with the jQuery DatePicker, their website says it can be localized, however that doesn't seem to work. I am using ASPNET.MVC, and I really want to stick to one javascript library. In this case jQuery. The ajax toolkit calendar would be acceptable, if only it too would display Norwegian names. Update: Awesome! I see I am missing the language files, a not so minor detail :-)

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  • How to bind a table in a dataset to a WPF datagrid in C# and XAML

    - by Jim Thomas
    I have been searching to hours for something very simple: bind a WPF datagrid to a datatable in order to see the columns at design-time. I can’t get any of the examples to work for me. Here is the C# code to populate the datatable InfoWork inside the dataset info: info = new Info(); InfoTableAdapters.InfoWorkTableAdapter adapter = new InfoTableAdapters.InfoWorkTableAdapter(); adapter.Fill(info.InfoWork); The problem is no matter how I declare ‘info’ or ‘infoWork’ Visual Studio/XAML can’t find it. I have tried: <Window.Resources> <ObjectDataProvider x:Key="infoWork" ObjectType="{x:Type local:info}" /> </Window.Resources> I have also tried this example from wpf.codeplex, but XAML doesn’t even like the “local:” keyword! <Window.Resources> <local:info x:Key="infoWork"/> </Window.Resources> There are really two main questions here: 1) How do I declare the table InfoWork in C# so that XAML can see it? I tried declaring it Public in the window class that XAML exists in with no success. 2) How do I declare the windows resource in XAML, specifcally the datatable inside the dataset? Out of curiosity, is there a reason that ItemsSource just doesn't show up as a property that be set in the properties design window?

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  • Is the Silverstripe CMS as easy to deploy, maintain, and develop on as it appears?

    - by Thomas Owens
    Although I haven't thought about deploying it on my own site, someone I know sent me a link to a CMS called SilverStripe that I've never heard of before. I read their site, looked at and played around with their demo, and so on. It looks like it's a CMS backed by a custom PHP framework that they call Sapphire. And from what I can gather on their website and using their demo, it potentially might be as good and easy as they say (once you get past any learning curve, which appears to be small, considering it looks a lot like other PHP frameworks and CMSes). Has anyone here ever deployed, maintained, or developed a CMS using SilverStripe? If so, could you shed some light on it, from a developer's point-of-view? I also found this earlier question about SilverStripe here on StackOverflow, but I'm more interested from a development point of view than a user or administrator point of view.

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  • Automatically install and launch a code-signed application from Safari

    - by Thomas Jung
    Is it possible and if so what are the steps necessary to package (or build) a Mac OS X application and code-sign it so that it can be downloaded with Safari and automatically launch? ... possibly after the user responds to some sort of dialog explaining that it is a signed application and the publisher has been verified. An example of the user experience I am trying to create is "installing Google Chrome for the first time on Windows", which is a 3-click, less-than-a-minute process. For the concerned among you: I am not trying to create a drive-by download. I am fine with some sort of intermittent user step approving the download. I just want to make the installation as quick and painless as possible and not require the user drag the app from a mounted DMG into the application folder. This may not 100% jibe with established Mac OS X user interaction guidelines, but it would work better for the not-power users. I only need the high-level steps or pointers to resources ... my google-fu was weak on this one.

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  • Get children count via HQL

    - by Thomas Lötzer
    Hi, I have a one-to-many mapping between a parent entity and child entities. Now I need to find the number of children associated with each parent for a list of parents. I am trying to do this with HQL but I am not sure how I can get the list of parents in there. Also, I don't know how I can return the entity itself and not just its ID. My current HQL query is: select new map(parent.id as parentId, count(*) as childCount) from Parent parent left join parent.children children group by parent.id but this only returns the ID and does not filter on specific parents. EDIT Based on Pascal's answer I have modified the query to select new map(parent as parent, count(elements(parent.children)) as childCount) from Parent parent group by parent That does work, but is prohibitively slow: 30 seconds instead of 400 ms on the same database.

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  • std::map operator[] and automatically created new objects

    - by thomas-gies
    I'm a little bit scared about something like this: std::map<DWORD, DWORD> tmap; tmap[0]+=1; tmap[0]+=1; tmap[0]+=1; Since DWORD's are not automatically initialized, I'm always afraid of tmap[0] being a random number that is incremented. How does the map know hot to initialize a DWORD if the runtime does not know how to do it? Is it guaranteed, that the result is always tmap[0] == 3?

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  • Applying Domain Model on top of Linq2Sql entities

    - by Thomas
    I am trying to practice the model first approach and I am putting together a domain model. My requirement is pretty simple: UserSession can have multiple ShoppingCartItems. I should start off by saying that I am going to apply the domain model interfaces to Linq2Sql generated entities (using partial classes). My requirement translates into three database tables (UserSession, Product, ShoppingCartItem where ProductId and UserSessionId are foreign keys in the ShoppingCartItem table). Linq2Sql generates these entities for me. I know I shouldn't even be dealing with the database at this point but I think it is important to mention. The aggregate root is UserSession as a ShoppingCartItem can not exist without a UserSession but I am unclear on the rest. What about Product? It is defiently an entity but should it be associated to ShoppingCartItem? Here are a few suggestion (they might all be incorrect implementations): public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItem> ShoppingCartItems{ get; set; } } public interface IShoppingCartItem { public Guid UserSessionId { get; set; } public int ProductId { get; set; } } Another one would be: public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItem> ShoppingCartItems{ get; set; } } public interface IShoppingCartItem { public Guid UserSessionId { get; set; } public IProduct Product { get; set; } } A third one is: public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItemColletion> ShoppingCartItems{ get; set; } } public interface IShoppingCartItemColletion { public IUserSession UserSession { get; set; } public IProduct Product { get; set; } } public interface IProduct { public int ProductId { get; set; } } I have a feeling my mind is too tightly coupled with database models and tables which is making this hard to grasp. Anyone care to decouple?

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  • Is it possible to easily convert SqlCommand to T-SQL string ?

    - by Thomas Wanner
    I have a populated SqlCommand object containing the command text and parameters of various database types along with their values. What I need is a T-SQL script that I could simply execute that would have the same effect as calling the ExecuteNonQuery method on the command object. Is there an easy way to do such "script dump" or do I have to manually construct such script from the command object ?

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  • SQL Server Compact with Visual Studio 2008

    - by Thomas
    I am running SQL server 2008 and Visual Studio 2008 on Vista. I downloaded SQL server compact 3.5 SP1 from Microsofts website and ran the install. When I open the server explorer for any windows application that I'm working on with VS 2008 and right click on data connections and then on add a connection a dialog comes up with available data providers. The problem is that SQL compact is not one of the options. Any idea why SQL compact is not showing up as a data provider in VS 2008?

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  • Database tables - how many database?

    - by Thomas
    How many databases are needed for a social website? I have my tech team working on developing a social site but all their tables are in 1 database. I wanted to create separate table sets for user data, temporary tables, etc and thinking maybe have one separate database only for critical data, etc but I am not a tech person and now sure how this works? The site is going to be a local reviews website.

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  • ruby write newline character to file but do not interpret as a true newline

    - by thomas
    I am trying to write a ruby string to a file in such a way that any newline characters embedded in the string remain embedded. This is being written out to a file which will then be processed by another tool. An example is below. I want this: 1 [label="this is a\ntest"] \n (second \n is a true newline) I have tried this: string = '1 [label="this is a\ntest"]' + "\n" Any thoughts?

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  • [Doxygen] How to documenting global dependencies for functions?

    - by Thomas Matthews
    I've got some C code from a 3rd party vendor (for an embedded platform) that uses global variables (for speed & space optimizations). I'm documenting the code, converting to Doxygen format. How do I put a note in the function documentation that the function requires on global variables and functions? Doxygen has special commands for annotating parameters and return values as describe here: Doxygen Special Commands. I did not see any commands for global variables. Example C code: extern unsigned char data_buffer[]; //!< Global variable. /*! Returns the next available data byte. * \return Next data byte. */ unsigned char Get_Byte(void) { static unsigned int index = 0; return data_buffer[index++]; //!< Uses global variable. } In the above code, I would like to add Doxygen comments that the function depends on the global variable data_buffer.

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