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  • Learn Prolog Now! DCG Practice Example

    - by Timothy
    I have been progressing through Learn Prolog Now! as self-study and am now learning about Definite Clause Grammars. I am having some difficulty with one of the Practical Session's tasks. The task reads: The formal language anb2mc2mdn consists of all strings of the following form: an unbroken block of as followed by an unbroken block of bs followed by an unbroken block of cs followed by an unbroken block of ds, such that the a and d blocks are exactly the same length, and the c and d blocks are also exactly the same length and furthermore consist of an even number of cs and ds respectively. For example, ε, abbccd, and aaabbbbccccddd all belong to anb2mc2mdn. Write a DCG that generates this language. I am able to write rules that generate andn, b2mc2m, and even anb2m and c2mndn... but I can't seem to join all these rules into anb2mc2mdn. The following are my rules that can generate andn and b2mc2m. s1 --> []. s1 --> a,s1,d. a --> [a]. d --> [d]. s2 --> []. s2 --> c,c,s2,d,d. c --> [c]. d --> [d]. Is anb2mc2mdn really a CFG, and is it possible to write a DCG using only what was taught in the lesson (no additional arguments or code, etc)? If so, can anyone offer me some guidance how I can join these so that I can solve the given task?

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  • Is it multitasking?

    - by Newbie
    Consider the below program myThread = new Thread( new ThreadStart( delegate { Method1(); Method2(); } ) ); Is it that 2 threads are getting called parallely(multitasking) or a single thread is calling the methods sequentially? It's urgent.

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  • PHP: MVC and DRY

    - by Pirkka
    Hello! Question about controllers. Can controller call it`s own class methods inside an action? EDIT: Oh sorry. I meant I dont want to repeat myself. :)

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  • Python script to remove all comments from XML file

    - by Jennifer Greentree
    I am trying to build a python script that will take in an XML document and remove all of the comment blocks from it. I tried something along the lines of: tree = ElementTree() tree.parse(file) commentElements = tree.findall('//comment()') for element in commentElements: element.parentNode.remove(element) Doing this yields a weird error from python: "KeyError: '()' I know there are ways to easily edit the file using other methods ( like sed ), but I have to do it in a python script.

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  • When transactionManager is not named "transactionManager" ...

    - by smallufo
    I am trying Spring 3(.0.2.RELEASE) and JPA2 and Hibernate 3.5.1-Final... One thing upsets me is that spring seems only accept a transaction Manager named "transactionManager" If I don't name it "transactionManager" , Spring will throws NoSuchBeanDefinitionException: No bean named 'transactionManager' is defined. Here is my config : <context:component-scan base-package="destiny.data.mining"/> <context:annotation-config/> <bean id="miningEntityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="mining"/> </bean> <bean id="miningTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" > <property name="entityManagerFactory" ref="miningEntityManagerFactory"/> </bean> <tx:advice id="txAdviceMining" transaction-manager="miningTransactionManager"> <tx:attributes> <tx:method name="get*" read-only="true"/> <tx:method name="save*" propagation="REQUIRED"/> <tx:method name="update*" propagation="REQUIRED"/> <tx:method name="delete*" propagation="REQUIRED"/> <tx:method name="*" propagation="SUPPORTS" read-only="true"/> </tx:attributes> </tx:advice> <aop:config> <aop:pointcut id="methods" expression="execution(* destiny.utils.AbstractDao+.*(..))"/> <aop:advisor advice-ref="txAdviceMining" pointcut-ref="methods"/> </aop:config> <tx:annotation-driven transaction-manager="miningTransactionManager"/> In this config , an Entity Manager Factory is not necessarily named "entityManagerFactory" , and "txAdvice" is not necessarily named "txAdvice" , either. But I don't know why on earth Spring requires a transaction manager named "transactionManager" ? Is there any way not to name a transaction manager "transactionManager" ? (I'm running multiple spring config files , so I try my best to avoid name-conflicting) test code : @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations={"classpath:mining.xml"}) public class MiningPersonDaoTest { @Inject private EntityManagerFactory miningEntityManagerFactory; @Inject private MiningPersonDao miningPersonDao; @Transactional @Test public void testUpdate() { MiningPerson p = miningPersonDao.get(42L); p.setLocationName("OOXX"); miningPersonDao.update(p); System.out.println(p); } } ii

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  • Use .NET in VB6 or classical ASP

    - by Michael
    Duplicate of Calling .NET methods from VB6 via COM visible DLL Which ways exist to use/call .NET classes/functions/libraries (.net 3.x) in VB6 or classical ASP ? Has anybody experiences with that ? How much effort is necessary to wrap .NET to COM ? Are there tools which help ?

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  • Refactoring Singleton Overuse

    - by drharris
    Today I had an epiphany, and it was that I was doing everything wrong. Some history: I inherited a C# application, which was really just a collection of static methods, a completely procedural mess of C# code. I refactored this the best I knew at the time, bringing in lots of post-college OOP knowledge. To make a long story short, many of the entities in code have turned out to be Singletons. Today I realized I needed 3 new classes, which would each follow the same Singleton pattern to match the rest of the software. If I keep tumbling down this slippery slope, eventually every class in my application will be Singleton, which will really be no logically different from the original group of static methods. I need help on rethinking this. I know about Dependency Injection, and that would generally be the strategy to use in breaking the Singleton curse. However, I have a few specific questions related to this refactoring, and all about best practices for doing so. How acceptable is the use of static variables to encapsulate configuration information? I have a brain block on using static, and I think it is due to an early OO class in college where the professor said static was bad. But, should I have to reconfigure the class every time I access it? When accessing hardware, is it ok to leave a static pointer to the addresses and variables needed, or should I continually perform Open() and Close() operations? Right now I have a single method acting as the controller. Specifically, I continually poll several external instruments (via hardware drivers) for data. Should this type of controller be the way to go, or should I spawn separate threads for each instrument at the program's startup? If the latter, how do I make this object oriented? Should I create classes called InstrumentAListener and InstrumentBListener? Or is there some standard way to approach this? Is there a better way to do global configuration? Right now I simply have Configuration.Instance.Foo sprinkled liberally throughout the code. Almost every class uses it, so perhaps keeping it as a Singleton makes sense. Any thoughts? A lot of my classes are things like SerialPortWriter or DataFileWriter, which must sit around waiting for this data to stream in. Since they are active the entire time, how should I arrange these in order to listen for the events generated when data comes in? Any other resources, books, or comments about how to get away from Singletons and other pattern overuse would be helpful.

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  • How to get path from a variable

    - by yoshco
    Following http://stackoverflow.com/questions/659647/how-to-get-folder-path-from-file-path-with-cmd I want to strip the path (without the filename) from a variable. following the logic of the methods discussed above I would like to use batch bellow, which doesn't work. any takers? possible? set cpp="C:\temp\lib.dll" echo %cpp% "C:\temp\lib.dll" echo %~dpcpp "C:\temp\" > doesn't work

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  • jQuery each doesn't have a callback-possibility?

    - by Martti Laine
    Hello I have a loop created with each, check this example: $('.foo').each(function(i){ //do stuff }); Is there any possibility to run a functions when this loop has ended? Couldn't find it on docs or Google. I can make it work without this kind of solution, but it's always good to search for and use the simpliest methods. Martti Laine

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  • Get metadata out of a webHttpBinding endpoint

    - by decyclone
    Hi, With a reference to my previous question, I would like to know how would I extract information of a WCF service from a client application to know what methods/types are exposed if the service exposes only one endpoint that uses webHttpBinding? Just to summarize, in my previous question, I came to know that an endpoint using webHttpBinding does not get exposed in the generated WSDL because it would be a JSON endpoint and is just not compatible.

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  • Make OS open directory in Python

    - by Vidar
    I am writing a program in Python, and want to get it to make the OS open the current working directory, making for instance Windows open explorer.exe and navigating to the wanted directory. Any ideas on how to do this? The directory is already given by os.getcwd. Cross platform methods preferred :)

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  • Running a method for infinitely in google app engine/Gwt

    - by sonam
    I am having a a method which listens continuously to a stream from a server and writes that data to datastore in google app which is later on retrieved by other methods. How can i do that in google app engine i.e calling that method one time during the starting of app and having it running for unlimited time without affecting other things. I am new to java world,So please help from that point of view also.How's that done in Java?

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  • Java Save Object to File

    - by Kristian Matthews
    I've tried implementing various methods from around the internet, all seem to be providing the same solution. But it just won't work and I'm unsure why, it creates the file, however, it's blank and if I try loading that file, it has an error. Main.java contains the code to save and load the file: 190-224. Rooms.java contains the object. Code Any help is greatly appreciated, I've been trying for almost a week now! Thanks in advanced!

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  • Java: Difference between PrintStream and PrintWriter

    - by Martijn Courteaux
    Hi, What is the difference between PrintStream and PrintWriter? They have much methods in common. I always mix up this classes because of that reason. And I think we can use them for exactly the same. But there has to be a difference. Otherwise there was only one class. I first searched on StackOverflow, but not yet this question. Thanks

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  • how to parse self closing tag in xml file

    - by ajay-sharma2
    Hi, I am working on an iphone application in which I am consuming a webservice. So i am parsing the XML file data. any idea about how to parse self closing tag like: State/ and how to read data of self tag like: Contact Email="[email protected]" Name="PhD" Phone="123-521-3388" Source="location"/ I am parsing xml file using NSXMLPARSER class methods and library Thanks,

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  • C++ class member functions instantiated by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched Stack Overflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state information was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (VC++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • A question about making a C# class persistent during a file load

    - by Adam
    Apologies for the indescriptive title, however it's the best I could think of for the moment. Basically, I've written a singleton class that loads files into a database. These files are typically large, and take hours to process. What I am looking for is to make a method where I can have this class running, and be able to call methods from within it, even if it's calling class is shut down. The singleton class is simple. It starts a thread that loads the file into the database, while having methods to report on the current status. In a nutshell it's al little like this: public sealed class BulkFileLoader { static BulkFileLoader instance = null; int currentCount = 0; BulkFileLoader() public static BulkFileLoader Instance { // Instanciate the instance class if necessary, and return it } public void Go() { // kick of 'ProcessFile' thread } public void GetCurrentCount() { return currentCount; } private void ProcessFile() { while (more rows in the import file) { // insert the row into the database currentCount++; } } } The idea is that you can get an instance of BulkFileLoader to execute, which will process a file to load, while at any time you can get realtime updates on the number of rows its done so far using the GetCurrentCount() method. This works fine, except the calling class needs to stay open the whole time for the processing to continue. As soon as I stop the calling class, the BulkFileLoader instance is removed, and it stops processing the file. What I am after is a solution where it will continue to run independently, regardless of what happens to the calling class. I then tried another approach. I created a simple console application that kicks off the BulkFileLoader, and then wrapped it around as a process. This fixes one problem, since now when I kick off the process, the file will continue to load even if I close the class that called the process. However, now the problem I have is that cannot get updates on the current count, since if I try and get the instance of BulkFileLoader (which, as mentioned before is a singleton), it creates a new instance, rather than returning the instance that is currently in the executing process. It would appear that singletons don't extend into the scope of other processes running on the machine. In the end, I want to be able to kick off the BulkFileLoader, and at any time be able to find out how many rows it's processed. However, that is even if I close the application I used to start it. Can anyone see a solution to my problem?

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  • Organising UI code in .NET forms

    - by sb3700
    Hi I'm someone who has taught myself programming, and haven't had any formal training in .NET programming. A while back, I started C# in order to develop a GUI program to control sensors, and the project has blossomed. I was just wondering how best to organise the code, particularly UI code, in my forms. My forms currently are a mess, or at least seem a mess to me. I have a constructor which initialises all the parameters and creates events. I have a giant State property, which updates the Enabled state of all my form control as users progress through the application (ie: disconnected, connected, setup, scanning) controlled by a States enum. I have 3-10 private variables accessed through properties, some of which have side-effects in changing the values of form elements. I have a lot of "UpdateXXX" functions to handle UI elements that depend on other UI elements - ie: if a sensor is changed, then change the baud rate drop down list. They are separated into regions I have a lot of events calling these Update functions I have a background worker which does all the scanning and analysis. My problem is this seems like a mess, particularly the State property, and is getting unmaintainable. Also, my application logic code and UI code are in the same file and to some degree, intermingled which seems wrong and means I need to do a lot of scrolling to find what I need. How do you structure your .net forms? Thanks

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  • How do I write object classes effectively when dealing with table joins?

    - by Chris
    I should start by saying I'm not now, nor do I have any delusions I'll ever be a professional programmer so most of my skills have been learned from experience very much as a hobby. I learned PHP as it seemed a good simple introduction in certain areas and it allowed me to design simple web applications. When I learned about objects, classes etc the tutor's basic examnples covered the idea that as a rule of thumb each database table should have its own class. While that worked well for the photo gallery project we wrote, as it had very simple mysql queries, it's not working so well now my projects are getting more complex. If I require data from two separate tables which require a table join I've instead been ignoring the class altogether and handling it on a case by case basis, OR, even worse been combining some of the data into the class and the rest as a separate entity and doing two queries, which to me seems inefficient. As an example, when viewing content on a forum I wrote, if you view a thread, I retrieve data from the threads table, the posts table and the user table. The queries from the user and posts table are retrieved via a join and not instantiated as an object, whereas the thread data is called using my Threads class. So how do I get from my current state of affairs to something a little less 'stupid', for want of a better word. Right now I have a DB class that deals with connection and escaping values etc, a parent db query class that deals with the common queries and methods, and all of the other classes (Thread, Upload, Session, Photo and ones thats aren't used Post, User etc ) are children of that. Do I make a big posts class that has the relevant extra attributes that I retrieve from the users (and potentially threads) table? Do I have separate classes that populate each of their relevant attributes with a single query? If so how do I do that? Because of the way my classes are written, based on what I was taught, my db update row method, or insert method both just take the attributes as an array and update all of that, if I have extra attributes from other db tables in each class then how do I rewrite those methods as obbiously updating automatically like that would result in errors? In short I think my understanding is limited right now and I'd like some pointers when it comes to the fundamentals of how to write more complex classes.

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