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  • Rails, if instance is in a scope?

    - by Joseph Silvashy
    I using rails 3 and I can't seem to check if a given instance is in a scope, see here: p = Post.find 6 +----+----------+-------------------------+-------------------------+-------------------------+-----------+ | id | title | publish_date | created_at | updated_at | published | +----+----------+-------------------------+-------------------------+-------------------------+-----------+ | 6 | asfdfdsa | 2010-03-28 22:33:00 UTC | 2010-03-28 22:33:46 UTC | 2010-03-28 22:33:46 UTC | true | +----+----------+-------------------------+-------------------------+-------------------------+-----------+ I have a menu scope which looks like: scope :menu, where("published != ?", false).limit(4) When I run it I get: Post.menu.all +----+------------------+------------------+------------------+-------------------+-----------+ | id | title | publish_date | created_at | updated_at | published | +----+------------------+------------------+------------------+-------------------+-----------+ | 1 | Lorem ipsum | 2010-03-23 07... | 2010-03-23 07... | 2010-03-28 21:... | true | | 2 | fdasf | 2010-03-28 21... | 2010-03-28 21... | 2010-03-28 21:... | true | | 3 | Ruby’s Imple... | 2010-03-28 21... | 2010-03-28 21... | 2010-03-28 21:... | true | | 4 | dsaD | 2010-03-28 22... | 2010-03-28 22... | 2010-03-28 22:... | true | +----+------------------+------------------+------------------+-------------------+-----------+ Which is correct, but if I try to check if p is in the the menu scope using: Post.menu.exists?(p) I get true when it should be false What is the proper way to find out if a given instance of something is in a scope?

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  • NSDate out of scope

    - by therealtkd
    Having problems with out of scope for NSDate in an iphone app. I have an interface defined like this: @interface MyObject : NSoObject { NSMutableArray *array; BOOL checkThis; NSDate *nextDue; } Now in the implementation I have this: -(id) init { if( (self=[super init]) ) { checkThis = NO; array = [[NSMutableArray alloc] init]; nextDue = [[NSDate date] retain]; NSDate *testDate = [NSDate date]; } return self; } Now, if I trace through the init, before I actually assign the variables checkThis shows as boolean. array shows as pointer 0x0 because it hasn't ben assigned. But the nextDue is showing as 'out of scope'. I don't understand why this is out of scope but the other variables aren't. If I trace through the code until after the variables are assigned, array now shows as being correctly assigned but nextDue is still out of scope. Interestingly, the testDate variable is assigned just fine and the debugger shows this as a valid date. Further interesting point is if I move the mouse over the testDate variable while I am debugging, it shows as an 'NSDate *' type which I would expect since that's its definition. Yet the nextDue, which to me is defined the same way is showing as a '_NSCFDate *'. Any googling I did on the subject said that the retain is the problem, but its actually out of scope before I even try to assign the variable. However, in another class, the same definition for NSDate work ok. It shows as nil before a value is assigned to it. Arghhh

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  • display tag scope issue with pagination

    - by sarah
    Hi All, I am using display tag for pagination ,i am reading the list from request scope and displaying it,i have kept the page size as 1 and the list hast 4 values,if i press next i get nothing to display this is the case with request scope but not with session scope how can i tackle this problem?

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  • Understanding DHCP setting for DNS Server Options and Scope Options

    - by Saariko
    I have installed 2 DC's on my network (W2K8 R2) both serve as a replicate DC on my domain. On one of them (DC1) there is also a DHCP server running. On both I have a DNS server running. I am trying to understand the difference in the settings within the DHCP of Server Options and Scope Options. As I understand it: On the server options, I should put an external DNS for system (lets say 8.8.8.8 - google) And on the scope options, I should put both my internal dc1 and dc2 IP's as the server. - which are than distributed to my domain clients. Is that correct? Is there a better way? Do I need to add loopback address as well?

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  • How to save data from multiple views of an iPhone app?

    - by DownUnder
    Hi Everyone. I'm making an app where I need to save the text in multiple views in the app when the app quits. I also need to be able to remove all of the data from just one of those views and when the app quits, it's possible not all of those views will have been created yet. After reading this post I thought perhaps it would be good to use a singleton that manages my app data which loads in the data when it is first requested and saved it when the app quits. Then in each view where I need to save data I can just set it on the singleton. I gave it a go but have run into some issues. At first I didn't synthesize the properties (as in the post I was using as a guide) but the compiler told me I needed to make getters and setters, so I did. Now when my applicationWIllTerminate: gets call the app crashes and the console says "Program received signal: “EXC_BAD_ACCESS”. kill quit". Is anyone able to tell me what I'm doing wrong, or suggest a better approach to saving the data? //SavedData.h #import <Foundation/Foundation.h> #define kFileName @"appData.plist" @interface SavedData : NSObject { NSString *information; NSString *name; NSString *email; NSString *phone; NSString *mobile; } @property(assign) NSString *information; @property(assign) NSString *name; @property(assign) NSString *email; @property(assign) NSString *phone; @property(assign) NSString *mobile; + (SavedData *)singleton; + (NSString *)dataFilePath; + (void)applicationWillTerminate:(NSNotification *)notification; @end //SavedData.m #import "SavedData.h" @implementation SavedData @synthesize information; @synthesize name; @synthesize email; @synthesize phone; @synthesize mobile; static SavedData * SavedData_Singleton = nil; + (SavedData *)singleton{ if (nil == SavedData_Singleton){ SavedData_Singleton = [[SavedData_Singleton alloc] init]; NSString *filePath = [self dataFilePath]; if([[NSFileManager defaultManager] fileExistsAtPath:filePath]){ NSMutableArray * array = [[NSMutableArray alloc] initWithContentsOfFile:filePath]; information = [array objectAtIndex:0]; name = [array objectAtIndex:1]; email = [array objectAtIndex:2]; phone = [array objectAtIndex:3]; mobile = [array objectAtIndex:4]; [array release]; } UIApplication *app = [UIApplication sharedApplication]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillTerminate:) name:UIApplicationWillTerminateNotification object:app]; } return SavedData_Singleton; } + (NSString *)dataFilePath{ NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *DocumentsDirectory = [paths objectAtIndex:0]; return [DocumentsDirectory stringByAppendingPathComponent:kFileName]; } + (void)applicationWillTerminate:(NSNotification *)notification{ NSLog(@"Application will terminate received"); NSMutableArray *array = [[NSMutableArray alloc] init]; [array addObject:information]; [array addObject:name]; [array addObject:email]; [array addObject:phone]; [array addObject:mobile]; [array writeToFile:[self dataFilePath] atomically:YES]; [array release]; } @end Then when I want to use it I do myLabel.text = [SavedData singleton].information; And when I change the field [SavedData singleton].information = @"my string"; Any help will be very much appreciated!

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  • Dependency Injection & Singleton Design pattern

    - by SysAdmin
    How do we identify when to use dependency injection or singleton pattern. I have read in lot of websites where they say "Use Dependency injection over singleton pattern". But I am not sure if I totally agree with them. For my small or medium scale projects I definitely see the use of singleton pattern straightforward. For example Logger. I could use Logger.GetInstance().Log(...) But, instead of this, why do I need to inject every class I create, with the logger's instance?.

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  • Singleton wrapper for Context

    - by kpdvx
    I'm considering creating a singleton wrapper for a Context so my model objects, if necessary, can open and read from a database connection. My model objects do not have access to a Context, and I'd like to avoid needing to pass a reference to a Context from object to object. I was planning to place into this singleton a reference to the Context returned by Application.getApplicationContext(). This singleton object would be initialized in my custom Application instance before anything else would need to or have a chance to use it. Can anyone think of a reason to not do this?

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  • Singletons, thread safety and structuremap

    - by Ben
    Hi, Currently I have the following class: public class PluginManager { private static bool s_initialized; private static object s_lock = new object(); public static void Initialize() { if (!s_initialized) { lock (s_lock) { if (!s_initialized) { // initialize s_initialized = true; } } } } } The important thing here is that Initialize() should only be executed once whilst the application is running. I thought that I would refactor this into a singleton class since this would be more thread safe?: public sealed class PluginService { static PluginService() { } private static PluginService _instance = new PluginService(); public static PluginService Instance { get { return _instance; } } private bool s_initialized; public void Initialize() { if (!s_initialized) { // initialize s_initialized = true; } } } Question one, is it still necessary to have the lock here (I have removed it) since we will only ever be working on the same instance? Finally, I want to use DI and structure map to initialize my servcices so I have refactored as below: public interface IPluginService { void Initialize(); } public class NewPluginService : IPluginService { private bool s_initialized; public void Initialize() { if (!s_initialized) { // initialize s_initialized = true; } } } And in my registry: ForRequestedType<IPluginService>() .TheDefaultIsConcreteType<NewPluginService>().AsSingletons(); This works as expected (singleton returning true in the following code): var instance1 = ObjectFactory.GetInstance<IPluginService>(); var instance2 = ObjectFactory.GetInstance<IPluginService>(); bool singleton = (instance1 == instance2); So my next question, is the structure map solution as thread safe as the singleton class (second example). The only downside is that this would still allow NewPluginService to be instantiated directly (if not using structure map). Many thanks, Ben

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  • How can I access variables outside of current scope in javascript?

    - by sekmet64
    I'm writing some application in javascript and cannot figure it out how to access the variables declared in my function, inside this jquery parse. Inside I can access global variables, but I don't really want to create global vars for these values. Basically I want to extract file names from an xml document in the simulationFiles variable. I check if the node attribute is equal with the simName and extract the two strings inside the xml elements, that part I think it's working. How can I extract those xml elements and append them to local variables? function CsvReader(simName) { this.initFileName = "somepath"; this.eventsFileName = "somepath"; $(simulationFiles).find('simulation').each(function() { if ($(this).attr("name") == simName) { initFileName += $(this).find("init").text(); eventsFileName += $(this).find("events").text(); } }); }

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  • My Oracle 9i package won't compile, says that a user-defined function is out of scope... but it isn'

    - by bitstream
    I have an Oracle package which contains user-defined functions and procedures, including two user-defined functions which are called from SELECT and UPDATE statements. The functions in question are defined before the procedures that call them. This piece of code compiles and works fine on Oracle 10g but won't compile on 9i. The code should work as-is according to Oracle's own documentation. Any idea why it would throw this error on 9i?

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  • Pass page scope attributes to a JSP using pagecontext.include for use in JSTL?

    - by hal10001
    We're using this JSP template solution almost verbatim at work: http://java.sun.com/developer/technicalArticles/javaserverpages/jsp_templates/ When it gets JSP pages to be included, it uses pageContext.include, which leaves us with one problem, and that is that we have a lot of scriplet code that gets initialized in the JSP itself (tag soup). My thought was to modify the template tag with an additional attribute that is a package path reference to a class with an init or execute method. That execute would get called first, and would add page context attributes before including the JSP. We would then use JSTL to access those attributes. However, I was told this wouldn't work because of how pageContext.include works, and the inability to pass through attributes scoped to the page. Is that true, and are there workarounds? I'm so-so on knowing all my scoping rules.

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  • What's the scope of a Python variable declared in an if statement?

    - by froadie
    I'm new to Python, so this is probably a simple scoping question. The following code in a Python file (module) is confusing me slightly: if __name__ == '__main__': x = 1 print x In other languages I've worked in, this code would throw an exception, as the x variable is local to the if statement and should not exist outside of it. But this code executes, and prints 1. Can anyone explain this behavior? Are all variables declared in a module global/available to the entire module?

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  • When should EntityManagerFactory instance be created/opened ?

    - by masato-san
    Ok, I read bunch of articles/examples how to write Entity Manager Factory in singleton. One of them easiest for me to understand a bit: http://javanotepad.blogspot.com/2007/05/jpa-entitymanagerfactory-in-web.html I learned that EntityManagerFactory (EMF) should only be created once preferably in application scope. And also make sure to close the EMF once it's used (?) So I wrote EMF helper class for business methods to use: public class EmProvider { private static final String DB_PU = "KogaAlphaPU"; public static final boolean DEBUG = true; private static final EmProvider singleton = new EmProvider(); private EntityManagerFactory emf; private EmProvider() {} public static EmProvider getInstance() { return singleton; } public EntityManagerFactory getEntityManagerFactory() { if(emf == null) { emf = Persistence.createEntityManagerFactory(DB_PU); } if(DEBUG) { System.out.println("factory created on: " + new Date()); } return emf; } public void closeEmf() { if(emf.isOpen() || emf != null) { emf.close(); } emf = null; if(DEBUG) { System.out.println("EMF closed at: " + new Date()); } } }//end class And my method using EmProvider: public String foo() { EntityManager em = null; List<Object[]> out = null; try { em = EmProvider.getInstance().getEntityManagerFactory().createEntityManager(); Query query = em.createNativeQuery(JPQL_JOIN); //just some random query out = query.getResultList(); } catch(Exception e) { //handle error.... } finally { if(em != null) { em.close(); //make sure to close EntityManager } } I made sure to close EntityManager (em) within method level as suggested. But when should EntityManagerFactory be closed then? And why EMF has to be singleton so bad??? I read about concurrency issues but as I am not experienced multi-thread-grammer, I can't really be clear on this idea.

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  • How do I resolve this scope issue in VB .NET?

    - by froadie
    I have a code structure something like this: For row = 1 To numRows Dim arrayIndex As Integer = 0 For column As Integer = bucketStartColumn To bucketEndColumn ' whatever code arrayIndex = arrayIndex + 1 Next Next Dim arrayIndex As Integer = 0 For column As Integer = bucketStartColumn To bucketEndColumn ' whatever code arrayIndex = arrayIndex + 1 Next Not exactly the code, so I don't really need suggestions about refactoring, but my problem is this - with this code I get a compiler error for the first Dim arrayIndex As Integer = 0 - "Variable 'arrayIndex' hides a variable in an enclosing block." As far as I can tell, arrayIndex is local to the first for loop and shouldn't exist by the time we reach the second loop. If I try to change the second declaration of arrayIndex to arrayIndex = 0, I get the error "Name 'arrayIndex' is not declared", as I expected. So is it visible, or not? Does this have something to do with the Dim keyword? Any suggestions of how to get around this, other than naming the second index variable something else?

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  • Purpose of singletons in programming

    - by thecoshman
    This is admittedly a rather loose question. My current understanding of singletons is that they are a class that you set up in such a way that only one instance is ever created. This sounds a lot like a static class to me. The main differnce being that with a static class you don't / can't instance it, you just use it such as Math.pi(). With a singletong class, you would still need to do something like singleton mySingleton = new singleton(); mysingleton.set_name("foo"); singleton otherSingleton = new singleton(); // correct me if i am wrong, but mysingleton == othersingleton right now, yes? // this the following should happen? otherSingleston.set_name("bar"); mysingleton.report_name(); // will output "bar" won't it? Please note, I am asking this language independently, more about the concept. So I am not so worried about actually how to coed such a class, but more why you would wan't to and what thing you would need to consider.

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  • will_paginate with named_scopes

    - by Lowgain
    I'm using will_paginate for pagination, which has been working well so far, except for this one thing. If I try to paginate a scope, for instance class User < ActiveRecord::Base named_scope :scope, lambda { etc } end User.scope.paginate({:page => params[:page], :per_page => 10}) That will tell me paginate is an undefined method. I'd rather not have to use a second solution for only this scope, is there something I can do here?

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  • DI and Singleton Pattern in one implementation

    - by Tony
    I want to refactor some code using the Windsor IOC/DI framework, but my issue is that I have some Singleton classes and Factory pattern classes and I am not sure that one can implement a Singleton or Factory using DI. Has anyone any ideas if that is possible and how?

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  • Passing arguments to scope_procedure in searchlogic

    - by Greg
    I'd like to use searchlogic's scope_procedure feature like so class MyModelObject < ActiveRecord::Base scope_procedure :my_scope_proc, lambda { |p1, p2| { :conditions => "p1 >= #{p1} AND p2 < #{p2}" }} end Then, I am doing the search: scope = MyModelObject.search(:my_scope_proc => true) scope.all The above code obviously doesn't work because I didn't pass p1 and p2 parameters to my named scope. I can't figure out how to pass parameters to the named scope.

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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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  • example for Singleton pattern

    - by JavaUser
    Hi, Please give me a real time example for singleton pattern . Different threads accessing a shared file is singleton or not ? Since each thread access the same instance of the file not individual instances of their own .

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  • RSpec and stubbing parameters for a named scope

    - by Andy Waite
    I'm try to write a spec for a named scope which is date dependent. The spec: it "should return 6 months of documents" do Date.stub!(:today).and_return(Date.new(2005, 03, 03)) doc_1 = Factory.create(:document, :date => '2005-01-01') Document.past_six_months.should == [doc_1] end The named scope in the Document model: named_scope :past_six_months, :conditions => ['date > ? AND date < ?', Date.today - 6.months, Date.today] The spec fails with an empty array, and the query in test.log shows why: SELECT * FROM "documents" WHERE (date > '2009-11-11' AND date < '2010-05-11') i.e. it appears to be ignoring my stubbed Date method. However, if I use a class method instead of a named scope then it passes: def self.past_six_months find(:all, :conditions => ['date > ? AND date < ?', Date.today - 6.months, Date.today]) end I would rather use the named scope approach but I don't understand why it isn't working.

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  • using pom for test scope dependencies

    - by IttayD
    Hi, Is it possible to create a pom file so it can be used inside another pom to add test scope dependencies? So in module E's pom.xml I have: <dependencies> <dependency> <groupId>com.example</artifactId> <artifactId>D</artifactId> <type>pom</type> <scope>test</scope> </dependency> </dependencies> So that if D's pom.xml contains dependencies on artifacts A, B, C, then these artifacts are in the compilation and execution classpath of E's tests. NOTE: the reason I want such a pom, and not rely on regular dependency resolution is that I have created a tests jar using maven-jar-plugin:test-jar and using that jar as a dependency causes maven to not use its transitive dependencies. (see http://jira.codehaus.org/browse/MNG-1378) UPDATE: this does not work for me (maybe because I'm trying to use it for the test scope): http://www.sonatype.com/books/mvnref-book/reference/pom-relationships-sect-pom-best-practice.html

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