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  • ByteBuffer recycling class

    - by Chris Dennett
    Hi everyone, I'm wonder how I'd code up a ByteBuffer recycling class that can get me a ByteBuffer which is at least as big as the specified length, and which can lock up ByteBuffer objects in use to prevent their use while they are being used by my code. This would prevent re-construction of DirectByteBuffers and such over and over, instead using existing ones. Is there an existing Java library which can do this very effectively? I know Javolution can work with object recycling, but does that extend to the ByteBuffer class in this context with the requirements set out? Cheers, Chris

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  • Query design in SQL - ORDER BY SUM() of field in rows which meet a certain condition

    - by Christian Mann
    OK, so I have two tables I'm working with - project and service, simplified thus: project ------- id PK name str service ------- project_id FK for project time_start int (timestamp) time_stop int (timestamp) One-to-Many relationship. Now, I want to return (preferably with one query) a list of an arbitrary number of projects, sorted by the total amount of time spent at them, which is found by SUM(time_stop) - SUM(time_start) WHERE project_id = something. So far, I have SELECT project.name FROM service LEFT JOIN project ON project.id = service.project_id LIMIT 100 but I cannot figure out how what to ORDER BY.

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  • Interface design pattern / Java / Seam

    - by Walter White
    Hi all, Is this possible somehow? @Name("geolocationService") public interface GeolocationService { @Query("SELECT g FROM Geolocation geolocation INNER JOIN geolocation.deployment deployment WHERE geolocation.ipStart <= INET_ATON(:ipAddress) AND deployment.active = TRUE") Geolocation findByIpAddress(@NamedParameter("ipAddress")final String ipAddress); } public GeolocationAction { @In private GeolocationService geolocationService; @RequestParameter("ipAddress") private String ipAddress; @Out private Geolocation geolocation; public void find() { geolocation = geolocationService.findByIpAddress(ipAddress); } } Is it possible to do this without implementing the interface? What is required to make that work? I want to maintain less and do more. If I can intercept invocations of the geolocationService then I am golden, how would I do that? I don't want it to ever be instantiated, so it will always be null (I don't want the @Name and @In annotations either then). Walter

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  • A quick design question about C++ container classes in shared memory

    - by recipriversexclusion
    I am writing a simple wrapper around boost::interprocess's vector container to implement a ring buffer in shared memory (shm) for IPC. Assume that buf is an instance of RingBuffer created in shm. Now, in its ctor, buf itself allocates a private boost::interprocess::vector data member to store values, e.g. m_data. My question is: I think m_data should also be created in shared memory. But it this a necessity? What happens if buf that was created in shm itself, allocates standard memory, i.e. using new. Does this get allocated on the calling process's heap? I don't think buf is allocated there so how come a data member that is private to an object not on a process's heap gets allocated there. I'm confused.

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  • Rails polymorphic associations, two assoc types in one class

    - by snitko
    Consider a class: class Link < ActiveRecord::Base has_many :link_votes, :as => :vote_subject, :class_name => 'Vote' has_many :spam_votes, :as => :vote_subject, :class_name => 'Vote' end The problem is, when I'm adding a new vote with @link.link_votes << Vote.new the vote_subject_type is 'Link', while I wish it could be 'link_votes' or something like that. Is this an AR limitation or is there a way to workaround this thing? I've actually found one related answer, but I'm not quite sure about what it says: http://stackoverflow.com/questions/1168047/polymorphic-association-with-multiple-associations-on-the-same-model/1764117#1764117

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  • non-class rvalues always have cv-unqualified types

    - by FredOverflow
    §3.10 section 9 says "non-class rvalues always have cv-unqualified types". That made me wonder... int foo() { return 5; } const int bar() { return 5; } void pass_int(int&& i) { std::cout << "rvalue\n"; } void pass_int(const int&& i) { std::cout << "const rvalue\n"; } int main() { pass_int(foo()); // prints "rvalue" pass_int(bar()); // prints "const rvalue" } According to the standard, there is no such thing as a const rvalue for non-class types, yet bar() prefers to bind to const int&&. Is this a compiler bug? EDIT: Apparently, this is also a const rvalue :)

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  • Is it possible to shorten my main function in this code?

    - by AjiPorter
    Is it possible for me to shorten my main() by creating a class? If so, what part of my code would most likely be inside the class? Thanks again to those who'll answer. :) #include <iostream> #include <fstream> #include <string> #include <ctime> #include <cstdlib> #define SIZE 20 using namespace std; struct textFile { string word; struct textFile *next; }; textFile *head, *body, *tail, *temp; int main() { ifstream wordFile("WORDS.txt", ios::in); // file object constructor /* stores words in the file into an array */ string words[SIZE]; char pointer; int i; for(i = 0; i < SIZE; i++) { while(wordFile >> pointer) { if(!isalpha(pointer)) { pointer++; break; } words[i] = words[i] + pointer; } } /* stores the words in the array to a randomized linked list */ srand(time(NULL)); int index[SIZE] = {0}; // temporary array of index that will contain randomized indexes of array words int j = 0, ctr; // assigns indexes to array index while(j < SIZE) { i = rand() % SIZE; ctr = 0; for(int k = 0; k < SIZE; k++) { if(!i) break; else if(i == index[k]) { // checks if the random number has previously been stored as index ctr = 1; break; } } if(!ctr) { index[j] = i; // assigns the random number to the current index of array index j++; } } /* makes sure that there are no double zeros on the array */ ctr = 0; for(i = 0; i < SIZE; i++) { if(!index[i]) ctr++; } if(ctr > 1) { int temp[ctr-1]; for(j = 0; j < ctr-1; j++) { for(i = 0; i < SIZE; i++) { if(!index[i]) { int ctr2 = 0; for(int k = 0; k < ctr-1; k++) { if(i == temp[k]) ctr2 = 1; } if(!ctr2) temp[j] = i; } } } j = ctr - 1; while(j > 0) { i = rand() % SIZE; ctr = 0; for(int k = 0; k < SIZE; k++) { if(!i || i == index[k]) { ctr = 1; break; } } if(!ctr) { index[temp[j-1]] = i; j--; } } } head = tail = body = temp = NULL; for(j = 0; j < SIZE; j++) { body = (textFile*) malloc (sizeof(textFile)); body->word = words[index[j]]; if(head == NULL) { head = tail = body; } else { tail->next = body; tail = body; cout << tail->word << endl; } } temp = head; while(temp != NULL) { cout << temp->word << endl; temp = temp->next; } return 0; }

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  • Domain driven design value object, how to ensure a unique value

    - by Darren
    Hi, I am building a questionnaire creator. A questionnaire consists of sections, sections consist of pages and pages consist of questions. Questionnaire is the aggregate root. Sections, pages and questions can have what are called shortcodes which should be unique within a questionnaire (but not unique within the database hence they are not strictly an identity). I intended to make the shortcode a value object and wanted to include the business rule that it should be unique within the questionnaire but I am unsure how to ensure that. My understanding is that the value object should not access the repository or service layer so how does it find out if it is unique? Thanks for any help. Darren

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  • Issue with child of custom Decorator class in WPF

    - by galacticgrug
    I need a custom border that renders a little differently than a normal border. I made a class that inherited from Decorator as follows class BetterBorder : Decorator { protected override Size ArrangeOverride(Size arrangeSize) { return arrangeSize; } protected override void OnRender(DrawingContext dc) { //these values are calculated elsewhere dc.DrawGeometry(backgroundBrush, borderPen, pathGeometry); } } //Properties and helper methods below this All of this works fine until I try to add a child to the control, the control can be added but is not visible and seems to be moved off BetterBorders visible client area. If I inherit from Border everything works fine, what am I missing?

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  • How to design a grid containing TextView in Android

    - by Cris
    Hello, i need to realize an app for Android using this background image: Over every cell i have to draw a TextView, but i don't know how to do it with the different screens; i have the background image with 3 resolutions (240x320, 320x480, 480x800) but i don't know what kind of layout to use; i would use GridView but i don't know if i can work with different column size. Can anyone help me? Thanks in advance

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  • Unit test class inherited from ContextBoundObject and decorated with ContextAttribute

    - by Joel Cunningham
    I am trying to retrofit unit tests on to some existing code base. Both the class and method I want to unit test is decorated with custom attributes that are inherited from ContextBoundObject and ContextAttribute. I dont want them to run as part of the unit test. The only solution I have come up with is to compile the attribute out when I want to unit test. I dont really like this solution and would prefer to either replace it with a mocked attribute at runtime or prevent the attribute from running in a more elegant way. How do you unit test code that has class and method attributes that inherit from ContextBoundObject and ContextAttribute that you dont want to run as part of a unit test? Thanks in advance.

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  • SQL database problems with addressbook table design

    - by Sebastian Hoitz
    Hello! I am writing a addressbook module for my software right now. I have the database set up so far that it supports a very flexible address-book configuration. I can create n-entries for every type I want. Type means here data like 'email', 'address', 'telephone' etc. I have a table named 'contact_profiles'. This only has two columns: id Primary key date_created DATETIME And then there is a table called contact_attributes. This one is a little more complex: id PK #profile (Foreign key to contact_profiles.id) type VARCHAR describing the type of the entry (name, email, phone, fax, website, ...) I should probably change this to a SET later. value Text (containing the value for the attribute). I can now link to these profiles, for example from my user's table. But from here I run into problems. At the moment I would have to create a JOIN for each value that I want to retrieve. Is there a possibility to somehow create a View, that gives me a result with the type's as columns? So right now I would get something like #profile type value 1 email [email protected] 1 name Sebastian Hoitz 1 website domain.tld But it would be nice to get a result like this: #profile email name website 1 [email protected] Sebastian Hoitz domain.tld The reason I do not want to create the table layout like this initially is, that there might always be things to add and I want to be able to have multiple attributes of the same type. So do you know if there is any possibility to convert this dynamically? If you need a better description please let me know. Thank you!

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  • Puppet - Possible to use software design patterns in modules?

    - by Mike Purcell
    As I work with puppet, I find myself wanting to automate more complex setups, for example vhosts for X number of websites. As my puppet manifests get more complex I find it difficult to apply the DRY (don't repeat yourself) principle. Below is a simplified snippet of what I am after, but doesn't work because puppet throws various errors depending up whether I use classes or defines. I'd like to get some feed back from some seasoned puppetmasters on how they might approach this solution. # site.pp import 'nodes' # nodes.pp node nodes_dev { $service_env = 'dev' } node nodes_prod { $service_env = 'prod' } import 'nodes/dev' import 'nodes/prod' # nodes/dev.pp node 'service1.ownij.lan' inherits nodes_dev { httpd::vhost::package::site { 'foo': } httpd::vhost::package::site { 'bar': } } # modules/vhost/package.pp class httpd::vhost::package { class manage($port) { # More complex stuff goes here like ensuring that conf paths and uris exist # As well as log files, which is I why I want to do the work once and use many notify { $service_env: } notify { $port: } } define site { case $name { 'foo': { class 'httpd::vhost::package::manage': port => 20000 } } 'bar': { class 'httpd::vhost::package::manage': port => 20001 } } } } } That code snippet gives me a Duplicate declaration: Class[Httpd::Vhost::Package::Manage] error, and if I switch the manage class to a define, and attempt to access a global or pass in a variable common to both foo and bar, I get a Duplicate declaration: Notify[dev] error. Any suggestions how I can implement the DRY principle and still get puppet to work? -- UPDATE -- I'm still having a problem trying to ensure that some of my vhosts, which may share a parent directory, are setup correctly. Something like this: node 'service1.ownij.lan' inherits nodes_dev { httpd::vhost::package::site { 'foo_sitea': } httpd::vhost::package::site { 'foo_siteb': } httpd::vhost::package::site { 'bar': } } What I need to happen is that sitea and siteb have the same parent "foo" folder. The problem I am having is when I call a define to ensure the "foo" folder exists. Below is the site define as I have it, hopefully it will make sense what I am trying to accomplish. class httpd::vhost::package { File { owner => root, group => root, mode => 0660 } define site() { $app_parts = split($name, '[_]') $app_primary = $app_parts[0] if ($app_parts[1] == '') { $tpl_path_partial_app = "${app_primary}" $app_sub = '' } else { $tpl_path_partial_app = "${app_primary}/${app_parts[1]}" $app_sub = $app_parts[1] } include httpd::vhost::log::base httpd::vhost::log::app { $name: app_primary => $app_primary, app_sub => $app_sub } } } class httpd::vhost::log { class base { $paths = [ '/tmp', '/tmp/var', '/tmp/var/log', '/tmp/var/log/httpd', "/tmp/var/log/httpd/${service_env}" ] file { $paths: ensure => directory } } define app($app_primary, $app_sub) { $paths = [ "/tmp/var/log/httpd/${service_env}/${app_primary}", "/tmp/var/log/httpd/${service_env}/${app_primary}/${app_sub}" ] file { $paths: ensure => directory } } } The include httpd::vhost::log::base works fine, because it is "included", which means it is only implemented once, even though site is called multiple times. The error I am getting is: Duplicate declaration: File[/tmp/var/log/httpd/dev/foo]. I looked into using exec, but not sure this is the correct route, surely others have had to deal with this before and any insight is appreciated as I have been grappling with this for a few weeks. Thanks.

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  • Multi Action with Form design streatgy

    - by Ravi
    Hello All, I want to have a controller that can handle multiple requests. Like a UserController handling all the addUser, deleteUser, updateUser and viewUser functionality. I know that MultiActionController can be used to bundle multiple similar request into one controller. But the functionalities like addUser and updateUser involves user to enter data, which the controller need to process. Can a MultiActionController handle doSubmit kind of methods (similar to SimpleFormController). Is there any better way to handle this kind of scenario? Thanks. Ravi

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  • Serializing Class Derived from Generic Collection yet Deserializing the Generic Collection

    - by Stacey
    I have a Repository Class with the following method... public T Single<T>(Predicate<T> expression) { using (var list = (Models.Collectable<T>)System.Xml.Serializer.Deserialize(typeof(Models.Collectable<T>), FileName)) { return list.Find(expression); } } Where Collectable is defined.. [Serializable] public class Collectable<T> : List<T>, IDisposable { public Collectable() { } public void Dispose() { } } And an Item that uses it is defined.. [Serializable] [System.Xml.Serialization.XmlRoot("Titles")] public partial class Titles : Collectable<Title> { } The problem is when I call the method, it expects "Collectable" to be the XmlRoot, but the XmlRoot is "Titles" (all of object Title). I have several classes that are collected in .xml files like this, but it seems pointless to rewrite the basic methods for loading each up when the generic accessors do it - but how can I enforce the proper root name for each file without hard coding methods for each one? The [System.Xml.Serialization.XmlRoot] seems to be ignored. When called like this... var titles = Repository.List<Models.Title>(); I get the exception <Titlesxmlns=''> was not expected. The XML is formatted such as. .. <?xml version="1.0" encoding="utf-16"?> <Titles xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Title> <Id>442daf7d-193c-4da8-be0b-417cec9dc1c5</Id> </Title> </Titles> Here is the deserialization code. public static T Deserialize<T>(String xmlString) { System.Xml.Serialization.XmlSerializer XmlFormatSerializer = new System.Xml.Serialization.XmlSerializer(typeof(T)); StreamReader XmlStringReader = new StreamReader(xmlString); //XmlTextReader XmlFormatReader = new XmlTextReader(XmlStringReader); try { return (T)XmlFormatSerializer.Deserialize(XmlStringReader); } catch (Exception e) { throw e; } finally { XmlStringReader.Close(); } }

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  • Application design in Spring MVC

    - by Ravi
    Hello All, I'm new to Spring MVC and trying out a simple project.It will contain a simple adding, viewing, updating and deleting user work flows. It will have login page and once authenticated the user will be taken to a welcome screen which will have links to add, view, update and delete users. Clicking on any of the links will take to individual pages where the user can do the specific tasks. What I'm doing here is, I'm using a MultiActionController to group together all requests related to User work flow. So the request from "Add User" link will handled by the addUser method in the UserController which will redirect the user to the "Add User" page, and the user can then fill in the details and save the new user. Now here is where I'm getting confused. Where should I put the save process of the new user, should I put that in new mehtod inside UserController, or use the same "addUser" method. What is the best way to handle this kind of scenario. I hope I was able to clear my question.

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  • Using a member function pointer within a class

    - by neuviemeporte
    Given an example class: class Fred { public: Fred() { func = &Fred::fa; } void run() { int foo, bar; *func(foo,bar); } double fa(int x, int y); double fb(int x, int y); private: double (Fred::*func)(int x, int y); }; I get a compiler error at the line calling the member function through the pointer "*func(foo,bar)", saying: "term does not evaluate to a function taking 2 arguments". What am I doing wrong?

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  • Quercus on Google App Engine: Class not loading

    - by gAMBOOKa
    Fatal Error: no matching class connection index.php <?php import database.connection; $connection = connection::get()->getPersistenceManager(); // ***ERROR HERE*** ?> connection.java package database; import javax.jdo.JDOHelper; import javax.jdo.PersistenceManagerFactory; public final class connection { private static final PersistenceManagerFactory pmfInstance = JDOHelper.getPersistenceManagerFactory("transactions-optional"); private connection() {} public static PersistenceManagerFactory get() { return pmfInstance; } } Quercus is otherwise configured fine, PHP implementation works smoothly on GAE. But when I try to initialize classes, PHP can't find them. What am I doing wrong?

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  • .net Value Class sorting with IComparable

    - by greggorob64
    I'm running into an issue using a DataGridView bound to a iBindingListView implementation (third party dll) attached to a large collection. There's a certain property in my collection type, named MyDateTime, which is a value class similar to DateTime, but also with some legacy code. This VALUE CLASS implements iComparable, iComparable<T>, and iEquatable<T>. The issue I'm having is this: When I apply a sort to the iBindingListView, or the Automatic Sorting provided by the DGV on the MyDateTimeColumn, it ALWAYS uses the non-generic iComparer, causing hundreds of thousands of unnecessary boxing and unboxing. When I remove the non-generic iComparer, the generic one is still not used, it just does a string compare on the .ToString(). Am I missing something? Why is my generic comparer not bieng called on a sort?

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  • objective-c default init method for class?

    - by Alex
    Hello, I have two differing methods for initializing my objective-c class. One is the default, and one takes a configuration parameter. Now, I'm pretty green when it comes to objective-c, but I've implemented these methods and I'm wondering if there's a better (more correct/in good style) way to handle initialization than the way I have done it. Meaning, did I write these initialization functions in accordance with standards and good style? It just doesn't feel right to check for the existence of selfPtr and then return based on that. Below are my class header and implementation files. Also, if you spot anything else that is wrong or evil, please let me know. I am a C++/Javascript developer who is learning objective-c as hobby and would appreciate any tips that you could offer. #import <Cocoa/Cocoa.h> // class for raising events and parsing returned directives @interface awesome : NSObject { // silence is golden. Actually properties are golden. Hence this emptiness. } // properties @property (retain) SBJsonParser* parser; @property (retain) NSString* eventDomain; @property (retain) NSString* appid // constructors -(id) init; -(id) initWithAppId:(id) input; // destructor -(void) dealloc; @end #import "awesome.h" #import "JSON.h" @implementation awesome - (id) init { if (self = [super init]) { // if init is called directly, just pass nil to AppId contructor variant id selfPtr = [self initWithAppId:nil]; } if (selfPtr) { return selfPtr; } else { return self; } } - (id) initWithAppId:(id) input { if (self = [super init]) { if (input = nil) { input = [[NSString alloc] initWithString:@"a369x123"]; } [self setAppid:input]; [self setEventDomain:[[NSString alloc] initWithString:@"desktop"]]; } return self; } // property synthesis @synthesize parser; @synthesize appid; @synthesize eventDomain; // destructor - (void) dealloc { self.parser = nil; self.appid = nil; self.eventDomain = nil; [super dealloc]; } @end Thanks!

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  • Can someone here explain constructors and destructors in python - simple explanation required - new

    - by rgolwalkar
    i will try to see if it makes sense :- class Person: '''Represnts a person ''' population = 0 def __init__(self,name): //some statements and population += 1 def __del__(self): //some statements and population -= 1 def sayHi(self): '''grettings from person''' print 'Hi My name is %s' % self.name def howMany(self): '''Prints the current population''' if Person.population == 1: print 'i am the only one here' else: print 'There are still %d guyz left ' % Person.population rohan = Person('Rohan') rohan.sayHi() rohan.howMany() sanju = Person('Sanjivi') sanju.howMany() del rohan # am i doing this correctly --- ? i need to get an explanation for this del - destructor O/P:- Initializing person data ****************************************** Initializing Rohan ****************************************** Population now is: 1 Hi My name is Rohan i am the only one here Initializing person data ****************************************** Initializing Sanjivi ****************************************** Population now is: 2 In case Person dies: ****************************************** Sanjivi Bye Bye world there are still 1 people left i am the only one here In case Person dies: ****************************************** Rohan Bye Bye world i am the last person on earth Population now is: 0 If required i can paste the whole lesson as well --- learning from :- http://www.ibiblio.org/swaroopch/byteofpython/read/

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