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• Framework for Everything - Where to begin? [Longer post]

  - by SquaredSoft

  Back story of this question, feel free to skip down for the specific question Hello, I've been very interested in the idea of abstract programming the last few years. I've made about 30 attempts at creating a piece of software that is capable of almost anything you throw at it. I've undertook some attempts at this that have taken upwards of a year, while getting close, never releasing it beyond my compiler. This has been something I've always tried wrapping my head around, and something is always missing. With the title, I'm sure you're assuming, "Yes of course you noob! You can't account for everything!" To which I have to reply, "Why not?" To give you some background into what I'm talking about, this all started with doing maybe a shade of gray hat SEO software. I found myself constantly having to create similar, but slightly different sets of code. I've gone through as many iterations of way to communicate on http as the universe has particles. "How many times am I going to have to write this multi-threaded class?" is something I found myself asking a lot. Sure, I could create a class library, and just work with that, but I always felt I could optimize what I had, which often was a large undertaking and typically involved frequent use of the CRTL+A keyboard shortcut, mixed with the delete button. It dawned on me that it was time to invest in a plugin system. This would allow me to simply add snippets of code. as time went on, and I could subversion stuff out, and distribute small chunks of code, rather than something that encompasses only a specific function or design. This comes with its own complexity, of course, and by the time I had finished the software scope for this addition, it hit me that I would want to add to everything in the software, not just a new http method, or automation code for a specific website. Great, we're getting more abstract. However, the software that I have in my mind comes down to a quite a few questions regarding its execution. I have to have some parameters to what I am going to do. After writing what the perfect software would do in my mind, I came up with this as a list of requirements: Should be able to use networking A "Macro" or "Expression system" which would allow people to do something like : =First(=ParseToList(=GetUrl("http://www.google.com?q=helloworld!"), Template.Google)) Multithreaded Able to add UI elements through some type of XML -- People can make their own addons etc. Can use third party API through the plugins, such as Microsoft CRM, Exchange, etc. This would allow the software to essentially be used for everything. Really, any task you wish to automate, in a simple way. Making the UI was as also extremely hard. How do you do all of this? Its very difficult. So my question: With so many attempts at this, I'm out of ideas how to successfully complete this. I have a very specific idea in my mind, but I keep failing to execute it. I'm a self taught programmer. I've been doing it for years, and work professionally in it, but I've never encountered something that would be as complex and in-depth as a system which essentially does everything. Where would you start? What are the best practices for design? How can I avoid constantly having to go back and optimize my software. What can I do to generalize this and draw everything out to completion. These are things I struggle with. P.s., I'm using c# as my main language. I feel like in this example, I might be hitting the outer limit of the language, although, I don't know if that is the case, or if I'm just a bad programmer. Thanks for your time.

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• Where should instantiated classes be stored?

  - by Eric C.

  I'm having a bit of a design dilemma here. I'm writing a library that consists of a bunch of template classes that are designed to be used as a base for creating content. For example: public class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template() { //constructor } public void DoSomething() { //does something } ... } The problem is, not only is the library providing the templates, it will also supply quite a few predefined templates which are instances of these template classes. The question is, where do I put these instances of the templates? The three solutions I've come up with so far are: 1) Provide serialized instances of the templates as files. On the one hand, this solution would keep the instances separated from the library itself, which is nice, but it would also potentially add complexity for the user. Even if we provided methods for loading/deserializing the files, they'd still have to deal with a bunch of files, and some kind of config file so the app knows where to look for those files. Plus, creating the template files would probably require a separate app, so if the user wanted to stick with the files method of storing templates, we'd have to provide some kind of app for creating the template files. Also, this requires external dependencies for testing the templates in the user's code. 2) Add readonly instances to the template class Example: public class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template PredefinedTemplate { get { Template templateInstance = new Template(); templateInstance.Name = "Some Name"; templateInstance.Description = "A description"; ... return templateInstance; } } public Template() { //constructor } public void DoSomething() { //does something } ... } This method would be convenient for users, as they would be able to access the predefined templates in code directly, and would be able to unit test code that used them. The drawback here is that the predefined templates pollute the Template type namespace with a bunch of extra stuff. I suppose I could put the predefined templates in a different namespace to get around this drawback. The only other problem with this approach is that I'd have to basically duplicate all the namespaces in the library in the predefined namespace (e.g. Templates.SubTemplates and Predefined.Templates.SubTemplates) which would be a pain, and would also make refactoring more difficult. 3) Make the templates abstract classes and make the predefined templates inherit from those classes. For example: public abstract class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template() { //constructor } public void DoSomething() { //does something } ... } and public class PredefinedTemplate : Template { public PredefinedTemplate() { this.Name = "Some Name"; this.Description = "A description"; this.Attribute1 = "Some Value"; ... } } This solution is pretty similar to #2, but it ends up creating a lot of classes that don't really do anything (none of our predefined templates are currently overriding behavior), and don't have any methods, so I'm not sure how good a practice this is. Has anyone else had any experience with something like this? Is there a best practice of some kind, or a different/better approach that I haven't thought of? I'm kind of banging my head against a wall trying to figure out the best way to go. Thanks!

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• Wicket, Spring and Hibernate - Testing with Unitils - Error: Table not found in statement [select re

  - by John

  Hi there. I've been following a tutorial and a sample application, namely 5 Days of Wicket - Writing the tests: http://www.mysticcoders.com/blog/2009/03/10/5-days-of-wicket-writing-the-tests/ I've set up my own little project with a simple shoutbox that saves messages to a database. I then wanted to set up a couple of tests that would make sure that if a message is stored in the database, the retrieved object would contain the exact same data. Upon running mvn test all my tests fail. The exception has been pasted in the first code box underneath. I've noticed that even though my unitils.properties says to use the 'hdqldb'-dialect, this message is still output in the console window when starting the tests: INFO - Dialect - Using dialect: org.hibernate.dialect.PostgreSQLDialect. I've added the entire dump from the console as well at the bottom of this post (which goes on for miles and miles :-)). Upon running mvn test all my tests fail, and the exception is: Caused by: java.sql.SQLException: Table not found in statement [select relname from pg_class] at org.hsqldb.jdbc.Util.sqlException(Unknown Source) at org.hsqldb.jdbc.jdbcStatement.fetchResult(Unknown Source) at org.hsqldb.jdbc.jdbcStatement.executeQuery(Unknown Source) at org.apache.commons.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:188) at org.hibernate.tool.hbm2ddl.DatabaseMetadata.initSequences(DatabaseMetadata.java:151) at org.hibernate.tool.hbm2ddl.DatabaseMetadata.(DatabaseMetadata.java:69) at org.hibernate.tool.hbm2ddl.DatabaseMetadata.(DatabaseMetadata.java:62) at org.springframework.orm.hibernate3.LocalSessionFactoryBean$3.doInHibernate(LocalSessionFactoryBean.java:958) at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:419) ... 49 more I've set up my unitils.properties file like so: database.driverClassName=org.hsqldb.jdbcDriver database.url=jdbc:hsqldb:mem:PUBLIC database.userName=sa database.password= database.dialect=hsqldb database.schemaNames=PUBLIC My abstract IntegrationTest class: @SpringApplicationContext({"/com/upbeat/shoutbox/spring/applicationContext.xml", "applicationContext-test.xml"}) public abstract class AbstractIntegrationTest extends UnitilsJUnit4 { private ApplicationContext applicationContext; } applicationContext-test.xml: <?xml version="1.0" encoding="UTF-8"? <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd" <bean id="dataSource" class="org.unitils.database.UnitilsDataSourceFactoryBean"/ </beans and finally, one of the test classes: package com.upbeat.shoutbox.web; import org.apache.wicket.spring.injection.annot.test.AnnotApplicationContextMock; import org.apache.wicket.util.tester.WicketTester; import org.junit.Before; import org.junit.Test; import org.unitils.spring.annotation.SpringBeanByType; import com.upbeat.shoutbox.HomePage; import com.upbeat.shoutbox.integrations.AbstractIntegrationTest; import com.upbeat.shoutbox.persistence.ShoutItemDao; import com.upbeat.shoutbox.services.ShoutService; public class TestHomePage extends AbstractIntegrationTest { @SpringBeanByType private ShoutService svc; @SpringBeanByType private ShoutItemDao dao; protected WicketTester tester; @Before public void setUp() { AnnotApplicationContextMock appctx = new AnnotApplicationContextMock(); appctx.putBean("shoutItemDao", dao); appctx.putBean("shoutService", svc); tester = new WicketTester(); } @Test public void testRenderMyPage() { //start and render the test page tester.startPage(HomePage.class); //assert rendered page class tester.assertRenderedPage(HomePage.class); //assert rendered label component tester.assertLabel("message", "If you see this message wicket is properly configured and running"); } } Dump from console when running mvn test: [INFO] Scanning for projects... [INFO] ------------------------------------------------------------------------ [INFO] Building shoutbox [INFO] task-segment: [test] [INFO] ------------------------------------------------------------------------ [INFO] [resources:resources {execution: default-resources}] [WARNING] File encoding has not been set, using platform encoding Cp1252, i.e. build is platform dependent! [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 3 resources [INFO] Copying 4 resources [INFO] [compiler:compile {execution: default-compile}] [INFO] Nothing to compile - all classes are up to date [INFO] [resources:testResources {execution: default-testResources}] [WARNING] File encoding has not been set, using platform encoding Cp1252, i.e. build is platform dependent! [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 2 resources [INFO] [compiler:testCompile {execution: default-testCompile}] [INFO] Nothing to compile - all classes are up to date [INFO] [surefire:test {execution: default-test}] [INFO] Surefire report directory: F:\Projects\shoutbox\target\surefire-reports INFO - ConfigurationLoader - Loaded main configuration file unitils-default.properties from classpath. INFO - ConfigurationLoader - Loaded custom configuration file unitils.properties from classpath. INFO - ConfigurationLoader - No local configuration file unitils-local.properties found. ------------------------------------------------------- T E S T S ------------------------------------------------------- Running com.upbeat.shoutbox.web.TestViewShoutsPage Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.02 sec INFO - Version - Hibernate Annotations 3.4.0.GA INFO - Environment - Hibernate 3.3.0.SP1 INFO - Environment - hibernate.properties not found INFO - Environment - Bytecode provider name : javassist INFO - Environment - using JDK 1.4 java.sql.Timestamp handling INFO - Version - Hibernate Commons Annotations 3.1.0.GA INFO - AnnotationBinder - Binding entity from annotated class: com.upbeat.shoutbox.models.ShoutItem INFO - QueryBinder - Binding Named query: item.getById = from ShoutItem item where item.id = :id INFO - QueryBinder - Binding Named query: item.find = from ShoutItem item order by item.timestamp desc INFO - QueryBinder - Binding Named query: item.count = select count(item) from ShoutItem item INFO - EntityBinder - Bind entity com.upbeat.shoutbox.models.ShoutItem on table SHOUT_ITEMS INFO - AnnotationConfiguration - Hibernate Validator not found: ignoring INFO - notationSessionFactoryBean - Building new Hibernate SessionFactory INFO - earchEventListenerRegister - Unable to find org.hibernate.search.event.FullTextIndexEventListener on the classpath. Hibernate Search is not enabled. INFO - ConnectionProviderFactory - Initializing connection provider: org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider INFO - SettingsFactory - RDBMS: HSQL Database Engine, version: 1.8.0 INFO - SettingsFactory - JDBC driver: HSQL Database Engine Driver, version: 1.8.0 INFO - Dialect - Using dialect: org.hibernate.dialect.PostgreSQLDialect INFO - TransactionFactoryFactory - Transaction strategy: org.springframework.orm.hibernate3.SpringTransactionFactory INFO - actionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended) INFO - SettingsFactory - Automatic flush during beforeCompletion(): disabled INFO - SettingsFactory - Automatic session close at end of transaction: disabled INFO - SettingsFactory - JDBC batch size: 1000 INFO - SettingsFactory - JDBC batch updates for versioned data: disabled INFO - SettingsFactory - Scrollable result sets: enabled INFO - SettingsFactory - JDBC3 getGeneratedKeys(): disabled INFO - SettingsFactory - Connection release mode: auto INFO - SettingsFactory - Default batch fetch size: 1 INFO - SettingsFactory - Generate SQL with comments: disabled INFO - SettingsFactory - Order SQL updates by primary key: disabled INFO - SettingsFactory - Order SQL inserts for batching: disabled INFO - SettingsFactory - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory INFO - ASTQueryTranslatorFactory - Using ASTQueryTranslatorFactory INFO - SettingsFactory - Query language substitutions: {} INFO - SettingsFactory - JPA-QL strict compliance: disabled INFO - SettingsFactory - Second-level cache: enabled INFO - SettingsFactory - Query cache: enabled INFO - SettingsFactory - Cache region factory : org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge INFO - FactoryCacheProviderBridge - Cache provider: org.hibernate.cache.HashtableCacheProvider INFO - SettingsFactory - Optimize cache for minimal puts: disabled INFO - SettingsFactory - Structured second-level cache entries: disabled INFO - SettingsFactory - Query cache factory: org.hibernate.cache.StandardQueryCacheFactory INFO - SettingsFactory - Echoing all SQL to stdout INFO - SettingsFactory - Statistics: disabled INFO - SettingsFactory - Deleted entity synthetic identifier rollback: disabled INFO - SettingsFactory - Default entity-mode: pojo INFO - SettingsFactory - Named query checking : enabled INFO - SessionFactoryImpl - building session factory INFO - essionFactoryObjectFactory - Not binding factory to JNDI, no JNDI name configured INFO - UpdateTimestampsCache - starting update timestamps cache at region: org.hibernate.cache.UpdateTimestampsCache INFO - StandardQueryCache - starting query cache at region: org.hibernate.cache.StandardQueryCache INFO - notationSessionFactoryBean - Updating database schema for Hibernate SessionFactory INFO - Dialect - Using dialect: org.hibernate.dialect.PostgreSQLDialect INFO - XmlBeanDefinitionReader - Loading XML bean definitions from class path resource [org/springframework/jdbc/support/sql-error-codes.xml] INFO - SQLErrorCodesFactory - SQLErrorCodes loaded: [DB2, Derby, H2, HSQL, Informix, MS-SQL, MySQL, Oracle, PostgreSQL, Sybase] INFO - DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@3e0ebb: defining beans [propertyConfigurer,dataSource,sessionFactory,shoutService,shoutItemDao,wicketApplication,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,transactionManager]; root of factory hierarchy INFO - sPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@a8e586: display name [org.springframework.context.support.ClassPathXmlApplicationContext@a8e586]; startup date [Tue May 04 18:19:58 CEST 2010]; root of context hierarchy INFO - XmlBeanDefinitionReader - Loading XML bean definitions from class path resource [com/upbeat/shoutbox/spring/applicationContext.xml] INFO - XmlBeanDefinitionReader - Loading XML bean definitions from class path resource [applicationContext-test.xml] INFO - DefaultListableBeanFactory - Overriding bean definition for bean 'dataSource': replacing [Generic bean: class [org.apache.commons.dbcp.BasicDataSource]; scope=singleton; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=close; defined in class path resource [com/upbeat/shoutbox/spring/applicationContext.xml]] with [Generic bean: class [org.unitils.database.UnitilsDataSourceFactoryBean]; scope=singleton; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in class path resource [applicationContext-test.xml]] INFO - sPathXmlApplicationContext - Bean factory for application context [org.springframework.context.support.ClassPathXmlApplicationContext@a8e586]: org.springframework.beans.factory.support.DefaultListableBeanFactory@5dfaf1 INFO - pertyPlaceholderConfigurer - Loading properties file from class path resource [application.properties] INFO - DefaultListableBeanFactory - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@5dfaf1: defining beans [propertyConfigurer,dataSource,sessionFactory,shoutService,shoutItemDao,wicketApplication,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,transactionManager]; root of factory hierarchy INFO - AnnotationBinder - Binding entity from annotated class: com.upbeat.shoutbox.models.ShoutItem INFO - QueryBinder - Binding Named query: item.getById = from ShoutItem item where item.id = :id INFO - QueryBinder - Binding Named query: item.find = from ShoutItem item order by item.timestamp desc INFO - QueryBinder - Binding Named query: item.count = select count(item) from ShoutItem item INFO - EntityBinder - Bind entity com.upbeat.shoutbox.models.ShoutItem on table SHOUT_ITEMS INFO - AnnotationConfiguration - Hibernate Validator not found: ignoring INFO - notationSessionFactoryBean - Building new Hibernate SessionFactory INFO - earchEventListenerRegister - Unable to find org.hibernate.search.event.FullTextIndexEventListener on the classpath. Hibernate Search is not enabled. INFO - ConnectionProviderFactory - Initializing connection provider: org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider INFO - SettingsFactory - RDBMS: HSQL Database Engine, version: 1.8.0 INFO - SettingsFactory - JDBC driver: HSQL Database Engine Driver, version: 1.8.0 INFO - Dialect - Using dialect: org.hibernate.dialect.PostgreSQLDialect INFO - TransactionFactoryFactory - Transaction strategy: org.springframework.orm.hibernate3.SpringTransactionFactory INFO - actionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended) INFO - SettingsFactory - Automatic flush during beforeCompletion(): disabled INFO - SettingsFactory - Automatic session close at end of transaction: disabled INFO - SettingsFactory - JDBC batch size: 1000 INFO - SettingsFactory - JDBC batch updates for versioned data: disabled INFO - SettingsFactory - Scrollable result sets: enabled INFO - SettingsFactory - JDBC3 getGeneratedKeys(): disabled INFO - SettingsFactory - Connection release mode: auto INFO - SettingsFactory - Default batch fetch size: 1 INFO - SettingsFactory - Generate SQL with comments: disabled INFO - SettingsFactory - Order SQL updates by primary key: disabled INFO - SettingsFactory - Order SQL inserts for batching: disabled INFO - SettingsFactory - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory INFO - ASTQueryTranslatorFactory - Using ASTQueryTranslatorFactory INFO - SettingsFactory - Query language substitutions: {} INFO - SettingsFactory - JPA-QL strict compliance: disabled INFO - SettingsFactory - Second-level cache: enabled INFO - SettingsFactory - Query cache: enabled INFO - SettingsFactory - Cache region factory : org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge INFO - FactoryCacheProviderBridge - Cache provider: org.hibernate.cache.HashtableCacheProvider INFO - SettingsFactory - Optimize cache for minimal puts: disabled INFO - SettingsFactory - Structured second-level cache entries: disabled INFO - SettingsFactory - Query cache factory: org.hibernate.cache.StandardQueryCacheFactory INFO - SettingsFactory - Echoing all SQL to stdout INFO - SettingsFactory - Statistics: disabled INFO - SettingsFactory - Deleted entity synthetic identifier rollback: disabled INFO - SettingsFactory - Default entity-mode: pojo INFO - SettingsFactory - Named query checking : enabled INFO - SessionFactoryImpl - building session factory INFO - essionFactoryObjectFactory - Not binding factory to JNDI, no JNDI name configured INFO - UpdateTimestampsCache - starting update timestamps cache at region: org.hibernate.cache.UpdateTimestampsCache INFO - StandardQueryCache - starting query cache at region: org.hibernate.cache.StandardQueryCache INFO - notationSessionFactoryBean - Updating database schema for Hibernate SessionFactory INFO - Dialect - Using dialect: org.hibernate.dialect.PostgreSQLDialect INFO - DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@5dfaf1: defining beans [propertyConfigurer,dataSource,sessionFactory,shoutService,shoutItemDao,wicketApplication,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,transactionManager]; root of factory hierarchy Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 1.34 sec <<< FAILURE! Running com.upbeat.shoutbox.integrations.ShoutItemIntegrationTest Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0 sec <<< FAILURE! Running com.upbeat.shoutbox.mocks.ShoutServiceTest Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.01 sec <<< FAILURE! Results : Tests in error: initializationError(com.upbeat.shoutbox.web.TestViewShoutsPage) testRenderMyPage(com.upbeat.shoutbox.web.TestHomePage) initializationError(com.upbeat.shoutbox.integrations.ShoutItemIntegrationTest) initializationError(com.upbeat.shoutbox.mocks.ShoutServiceTest) Tests run: 4, Failures: 0, Errors: 4, Skipped: 0 [INFO] ------------------------------------------------------------------------ [ERROR] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] There are test failures. Please refer to F:\Projects\shoutbox\target\surefire-reports for the individual test results. [INFO] ------------------------------------------------------------------------ [INFO] For more information, run Maven with the -e switch [INFO] ------------------------------------------------------------------------ [INFO] Total time: 3 seconds [INFO] Finished at: Tue May 04 18:19:58 CEST 2010 [INFO] Final Memory: 13M/31M [INFO] ------------------------------------------------------------------------ Any help is greatly appreciated.

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• Populating Models from other Models in Django?

  - by JT

  This is somewhat related to the question posed in this question but I'm trying to do this with an abstract base class. For the purposes of this example lets use these models: class Comic(models.Model): name = models.CharField(max_length=20) desc = models.CharField(max_length=100) volume = models.IntegerField() ... <50 other things that make up a Comic> class Meta: abstract = True class InkedComic(Comic): lines = models.IntegerField() class ColoredComic(Comic): colored = models.BooleanField(default=False) In the view lets say we get a reference to an InkedComic id since the tracer, err I mean, inker is done drawing the lines and it's time to add color. Once the view has added all the color we want to save a ColoredComic to the db. Obviously we could do inked = InkedComic.object.get(pk=ink_id) colored = ColoredComic() colored.name = inked.name etc, etc. But really it'd be nice to do: colored = ColoredComic(inked_comic=inked) colored.colored = True colored.save() I tried to do class ColoredComic(Comic): colored = models.BooleanField(default=False) def __init__(self, inked_comic = False, *args, **kwargs): super(ColoredComic, self).__init__(*args, **kwargs) if inked_comic: self.__dict__.update(inked_comic.__dict__) self.__dict__.update({'id': None}) # Remove pk field value but it turns out the ColoredComic.objects.get(pk=1) call sticks the pk into the inked_comic keyword, which is obviously not intended. (and actually results in a int does not have a dict exception) My brain is fried at this point, am I missing something obvious, or is there a better way to do this?

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• linebreak in url with Bibtex and hyperref package

  - by Tim

  Why is this item not shown properly in my bibliography? @misc{ann, abstract = {ANN is an implbmentation of nearest neighbor search.}, author = {David M. Mount and Sunil Arya}, howpublished = {\url{http://www.cs.umd.edu/~mount/ANN/}}, keywords = {knn}, posted-at = {2010-04-08 00:05:04}, priority = {2}, title = {ANN.}, url = "http://www.cs.umd.edu/~mount/ANN/", year = {2008} } @misc{Nilsson96introductionto, author = {Nilsson, Nils J.}, citeulike-article-id = {6995464}, howpublished = {\url{http://robotics.stanford.edu/people/nilsson/mlbook.html}}, keywords = {*file-import-10-04-11}, posted-at = {2010-04-11 06:52:28}, priority = {2}, title = {Introduction to Machine Learning: An Early Draft of a Proposed Textbook.}, year = {1996} } EDIT: I am using \usepackage{hyperref}, not \usepackage{url}. I don't know what changes I just made made the first item appear properly now @misc{ann, abstract = {ANN is an implbmentation of nearest neighbor search.}, author = {David M. Mount and Sunil Arya}, howpublished = {\url{http://www.cs.umd.edu/~mount/ANN/}}, keywords = {ann}, posted-at = {2010-04-08 00:05:04}, priority = {2}, title = {The \textsc{A}pproximate \textsc{N}earest \textsc{N}eighbor \textsc{S}earching \textsc{L}ibrary.}, url = "http://www.cs.umd.edu/~mount/ANN/", year = {2008} } EDIT: Since I am using hyperref package, it produces error when using url package together with it. So the two cannot work together? I would like to use hyper links inside pdf file, so I would like to use hyperref package instead of url package. I googled a bit, and try \usepackage[hyperindex,breaklinks]{hyperref}, but there is still no line break just as before. How can I do it? Is there conflict in the packages that I am now using?: \usepackage{amsmath} \usepackage{amsfonts} \usepackage[dvips]{graphicx} \usepackage{wrapfig} \graphicspath{{./figs/}} \DeclareGraphicsExtensions{.eps} \usepackage{fixltx2e} \usepackage{array} \usepackage{times} \usepackage{fancyhdr} \usepackage{multirow} \usepackage{algorithmic} \usepackage{algorithm} \usepackage{slashbox} \usepackage{multirow} \usepackage{rotating} \usepackage{longtable} \usepackage[hyperindex,breaklinks]{hyperref} \usepackage{forloop} \usepackage{lscape} \usepackage{supertabular} \usepackage{amssymb} \usepackage{amsthm}

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• How to approach ninject container/kernel in inheritance situation

  - by Bas

  I have the following situation: class RuleEngine {} abstract class RuleImplementation {} class RootRule : RuleImplementation {} class Rule1 : RuleImplementation {} class Rule2 : RuleImplementation {} The RuleEngine is injected by Ninject and has a kernel at it's disposal, the role of the RuleEngine is to fire off the root rule, which on it's turn will load all the other rules also using Ninject, but using a different Module and creating a new Kernel. Now my question is, some of the rules require some dependencies which I want to inject using Ninject. What would be the best way to create the kernel for these rules and also still do proper unit testing with it? (the kernel shouldn't become a real pain in my tests) I've been thinking of the following possibilitys: The kernel that I use in the RuleEngine class could be tossed around to RuleImplementation and thus be available for every rule. But tossing around Kernels isn't really something I wish to do. When creating the rules, I could give the kernel (which creates the rules) as a constructor argument for each rule. I could create a method inside the RuleImplementation which creates a kernel and makes it possible for the rules to retrieve the kernel using a get() in the abstract class Whats the convention of passing around/creating kernels? Just create new kernels, or reuse them?

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• Polymorphic NHibernate mappings

  - by Ben Aston

  I have an interface IUserLocation and a concrete type UserLocation. When I use ICriteria, specifying the interface IUserLocation, I want NHibernate to instantiate a collection of the concrete UserLocation type. I have created an HBM mapping file using the table per concrete type strategy (shown below). However, when I query NHibernate using ICriteria I get: NHibernate cannot instantiate abstract class or interface MyNamespace.IUserLocation Can anyone see why this is? (source code for the relevant bit of NHibernate here (I think)) My ICriteria: var filter = DetachedCriteria.For<IUserLocation>() .Add(Restrictions.Eq("UserId", userId)); return filter.GetExecutableCriteria(UoW.Session) .List<IUserLocation>(); My mapping file: <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-lazy="true"> <class xmlns="urn:nhibernate-mapping-2.2" name="MyNamespace.IUserLocation,MyAssembly" abstract="true" table="IUserLocations"> <composite-id> <key-property name="UserId" column="UserId" type="System.Guid"></key-property> <key-many-to-one name="Location" column="LocationId" class="MyNamespace.ILocation,MyAssembly"></key-many-to-one> </composite-id> <union-subclass table="UserLocations" name="MyNamespace2.UserLocation,MyAssembly2"> <property name="IsAdmin" /> </union-subclass> </class> </hibernate-mapping>

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• ASP.NET Content Web Form - content from placeholder disappears

  - by Naeem Sarfraz

  I'm attempting to set a class on the body tag in my asp.net site which uses a master page and content web forms. I simply want to be able to do this by adding a bodycssclass property (see below) to the content web form page directive. It works through the solution below but when i attempt to view Default.aspx the Content1 control loses its content. Any ideas why? Here is how I'm doing it. I have a master page with the following content: <%@ Master Language="C#" ... %> <html><head>...</head> <body id=ctlBody runat=server> <asp:ContentPlaceHolder ID="cphMain" runat="server" /> </body> </html> it's code behind looks like: public partial class Site : MasterPageBase { public override string BodyCssClass { get { return ctlBody.Attributes["class"]; } set { ctlBody.Attributes["class"] = value; } } } it inherits from: public abstract class MasterPageBase : MasterPage { public abstract string BodyCssClass { get; set; } } my default.aspx is defined as: <%@ Page Title="..." [master page definition etc..] bodycssclass="home" %> <asp:Content ID="Content1" ContentPlaceHolderID="cphMain" runat="server"> Some content </asp:Content> the code behind for this file looks like: public partial class Default : PageBase { ... } and it inherits from : public class PageBase : Page { public string BodyCssClass { get { MasterPageBase mpbCurrent = this.Master as MasterPageBase; return mpbCurrent.BodyCssClass; } set { MasterPageBase mpbCurrent = this.Master as MasterPageBase; mpbCurrent.BodyCssClass = value; } } }

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• NullReferenceException when testing DefaultModelBinder.

  - by Byron Sommardahl

  I'm developing a project using BDD/TDD techniques and I'm trying my best to stay the course. A problem I just ran into is unit testing the DefaultModelBinder. I'm using mspec to write my tests. I have a class like this that I want to bind to: public class EmailMessageInput : IMessageInput { public object Recipient { get; set; } public string Body { get; set; } } Here's how I'm building my spec context. I'm building a fake form collection and stuffing it into a bindingContext object. public abstract class given_a_controller_with_valid_email_input : given_a_controller_context { Establish additional_context = () => { var form = new FormCollection { new NameValueCollection { { "EmailMessageInput.Recipient", "[email protected]"}, { "EmailMessageInput.Body", "Test body." } } }; _bindingContext = new ModelBindingContext { ModelName = "EmailMessageInput", ValueProvider = form }; _modelBinder = new DefaultModelBinder(); }; protected static ModelBindingContext _bindingContext; protected static DefaultModelBinder _modelBinder; } public abstract class given_a_controller_context { protected static MessageController _controller; Establish context = () => { _controller = new MessageController(); }; } Finally, my spec throws an null reference exception when I execute .BindModel() from inside one of my specs: Because of = () => { _model = _modelBinder.BindModel(_controller.ControllerContext, _bindingContext); }; Any clue what it could be? Feel free to ask me for more info, if needed. I might have taken something for granted.

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• Proxy is created, and interceptor is in the __interceptors array, but the interceptor is never calle

  - by drewbu

  This is the first time I've used interceptors with the fluent registration and I'm missing something. With the following registration, I can resolve an IProcessingStep, and it's a proxy class and the interceptor is in the __interceptors array, but for some reason, the interceptor is not called. Any ideas what I'm missing? Thanks, Drew AllTypes.Of<IProcessingStep>() .FromAssembly(Assembly.GetExecutingAssembly()) .ConfigureFor<IProcessingStep>(c => c .Unless(Component.ServiceAlreadyRegistered) .LifeStyle.PerThread .Interceptors(InterceptorReference.ForType<StepLoggingInterceptor>()).First ), Component.For<StepMonitorInterceptor>(), Component.For<StepLoggingInterceptor>(), Component.For<StoreInThreadInterceptor>() public abstract class BaseStepInterceptor : IInterceptor { public void Intercept(IInvocation invocation) { IProcessingStep processingStep = (IProcessingStep)invocation.InvocationTarget; Command cmd = (Command)invocation.Arguments[0]; OnIntercept(invocation, processingStep, cmd); } protected abstract void OnIntercept(IInvocation invocation, IProcessingStep processingStep, Command cmd); } public class StepLoggingInterceptor : BaseStepInterceptor { private readonly ILogger _logger; public StepLoggingInterceptor(ILogger logger) { _logger = logger; } protected override void OnIntercept(IInvocation invocation, IProcessingStep processingStep, Command cmd) { _logger.TraceFormat("<{0}> for cmd:<{1}> - begin", processingStep.StepType, cmd.Id); bool exceptionThrown = false; try { invocation.Proceed(); } catch { exceptionThrown = true; throw; } finally { _logger.TraceFormat("<{0}> for cmd:<{1}> - end <{2}> times:<{3}>", processingStep.StepType, cmd.Id, !exceptionThrown && processingStep.CompletedSuccessfully ? "succeeded" : "failed", cmd.CurrentMetric==null ? "{null}" : cmd.CurrentMetric.ToString()); } } }

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• Implementing Struts 2 Interceptors using Struts 1

  - by Andriy Zakharchuk

  Hello all, I have a legacy application written with Struts 1. The only feature I was asked to add is to protect some actions. Currently any user can do whatever he/she wants. The idea is to allows all user see the data, but block modification operation, i.e. to modify data a user should log in. I know Struts2 has interceptors, so I could attach them to required actions and forward users to log in page when needed. But how can I do similar thing in Struts 1 application? My first idea was to create my own abstract Action class: public class AuthenticatedAction { public ActionForward execute( ActionMapping mapping, ActionForm form, HttpServletRequest theRequest, HttpServletResponse theResponse) { if (!logged) { // forward to log in form } else { doExecute(mapping, form, request, response); } } public abstract ActionForward doExecute( ActionMapping mapping, ActionForm form, HttpServletRequest theRequest, HttpServletResponse theResponse); } Then change all actions that require authentication from extends Action to extends AuthenticatedAction then add login form, login action (which performs authentications and puts this status into the session) and change JSP header tile to display authentication block, e.g., "You are (not logged in)/", Login/Logout. As I guess this should solve the problem. If this doesn't solve the problem, please explain me why. Is there any better (more elegant like interceptors are) way to do this? Thank you in advance.

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• Idiomatic Scala way to deal with base vs derived class field names?

  - by Gregor Scheidt

  Consider the following base and derived classes in Scala: abstract class Base( val x : String ) final class Derived( x : String ) extends Base( "Base's " + x ) { override def toString = x } Here, the identifier 'x' of the Derived class parameter overrides the field of the Base class, so invoking toString like this: println( new Derived( "string" ).toString ) returns the Derived value and gives the result "string". So a reference to the 'x' parameter prompts the compiler to automatically generate a field on Derived, which is served up in the call to toString. This is very convenient usually, but leads to a replication of the field (I'm now storing the field on both Base and Derived), which may be undesirable. To avoid this replication, I can rename the Derived class parameter from 'x' to something else, like '_x': abstract class Base( val x : String ) final class Derived( _x : String ) extends Base( "Base's " + _x ) { override def toString = x } Now a call to toString returns "Base's string", which is what I want. Unfortunately, the code now looks somewhat ugly, and using named parameters to initialize the class also becomes less elegant: new Derived( _x = "string" ) There is also a risk of forgetting to give the derived classes' initialization parameters different names and inadvertently referring to the wrong field (undesirable since the Base class might actually hold a different value). Is there a better way? Edit: To clarify, I really only want the Base values; the Derived ones just seem necessary for initializing the Base ones. The example only references them to illustrate the ensuing issues. It might be nice to have a way to suppress automatic field generation if the derived class would otherwise end up hiding a base class field.

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• ActiveRecord table inheritence using set_table_names

  - by Jinyoung Kim

  Hi, I'm using ActiveRecord in Ruby on Rails. I have a table named documents(Document class) and I want to have another table data_documents(DataDocument) class which is effectively the same except for having different table name. In other words, I want two tables with the same behavior except for table name. class DataDocument < Document #set_table_name "data_documents" self.table_name = "data_documents" end My solution was to use class inheritance as above, yet this resulted in inconsistent SQL statement for create operation where there are both 'documents' table and 'data_documents' table. Can you figure out why and how I can make it work? >> DataDocument.create(:did=>"dd") ActiveRecord::StatementInvalid: Mysql::Error: Unknown column 'data_documents.did' in 'where clause': SELECT `documents`.id FROM `documents` WHERE (`data_documents`.`did` = BINARY 'dd') LIMIT 1 from /Users/lifidea/.gem/ruby/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/abstract_adapter.rb:212:in `log' from /Users/lifidea/.gem/ruby/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/mysql_adapter.rb:320:in `execute' from /Users/lifidea/.gem/ruby/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/mysql_adapter.rb:595:in `select' from /Users/lifidea/.gem/ruby/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all_without_query_cache' from /Users/lifidea/.gem/ruby/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/abstract/query_cache.rb:62:in `select_all'

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• Specification Pattern and Boolean Operator Precedence

  - by Anders Nielsen

  In our project, we have implemented the Specification Pattern with boolean operators (see DDD p 274), like so: public abstract class Rule { public Rule and(Rule rule) { return new AndRule(this, rule); } public Rule or(Rule rule) { return new OrRule(this, rule); } public Rule not() { return new NotRule(this); } public abstract boolean isSatisfied(T obj); } class AndRule extends Rule { private Rule one; private Rule two; AndRule(Rule one, Rule two) { this.one = one; this.two = two; } public boolean isSatisfied(T obj) { return one.isSatisfied(obj) && two.isSatisfied(obj); } } class OrRule extends Rule { private Rule one; private Rule two; OrRule(Rule one, Rule two) { this.one = one; this.two = two; } public boolean isSatisfied(T obj) { return one.isSatisfied(obj) || two.isSatisfied(obj); } } class NotRule extends Rule { private Rule rule; NotRule(Rule obj) { this.rule = obj; } public boolean isSatisfied(T obj) { return !rule.isSatisfied(obj); } } Which permits a nice expressiveness of the rules using method-chaining, but it doesn't support the standard operator precedence rules of which can lead to subtle errors. The following rules are not equivalent: Rule<Car> isNiceCar = isRed.and(isConvertible).or(isFerrari); Rule<Car> isNiceCar2 = isFerrari.or(isRed).and(isConvertible); The rule isNiceCar2 is not satisfied if the car is not a convertible, which can be confusing since if they were booleans isRed && isConvertible || isFerrari would be equivalent to isFerrari || isRed && isConvertible I realize that they would be equivalent if we rewrote isNiceCar2 to be isFerrari.or(isRed.and(isConvertible)), but both are syntactically correct. The best solution we can come up with, is to outlaw the method-chaining, and use constructors instead: OR(isFerrari, AND(isConvertible, isRed)) Does anyone have a better suggestion?

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• Should i use a trigger or Behaviors for this?

  - by Michael

  I have an abstract object called Applicant and two different types of objects that inherit from Applicant called Business and Individual. So I have three classes that look like this: public abstract class Applicant { ... } public class Individual : Applicant { ... } public class Business : Applicant { ... } Now in the DataGrid I want to show all the details of Applicant object. When you choose a row I want to show details of either the business or individual as a internal grid. Something like this <DataGrid> <DataGrid.Columns> <!--Show different columns --> </DataGrid.Columns> <DataGrid.RowDetailsTemplate> <!--Show if Individual --> <DataGrid> <DataGrid.Columns> <DataGridTextColumn Header="First Name" ... /> <DataGridTextColumn Header="Last Name" ... /> </DataGrid.Columns> </DataGrid> <!--Show if business --> <DataGrid> <DataGrid.Columns> <DataGridTextColumn Header="Business Name" ... /> <DataGridTextColumn Header="Tax id" ... /> </DataGrid.Columns> </DataGrid> </DataGrid.RowDetailsTemplate> </DataGrid> Now I'm not sure if I need to use a Triggers or Behaviors to accomplish this? Thanks for everyones help! FYI I'm using Silverlight 4.0 with Prism.

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• What would you like to correct and/or improve in this java implementation of Chain Of Responsibility

  - by Maciek Kreft

  package design.pattern.behavioral; import design.pattern.behavioral.ChainOfResponsibility.*; public class ChainOfResponsibility { public static class Chain { private Request[] requests = null; private Handler[] handlers = null; public Chain(Handler[] handlers, Request[] requests){ this.handlers = handlers; this.requests = requests; } public void start() { for(Request r : requests) for (Handler h : handlers) if(h.handle(r)) break; } } public static class Request { private int value; public Request setValue(int value){ this.value = value; return this; } public int getValue() { return value; } } public static class Handler<T1> { private Lambda<T1> lambda = null; private Lambda<T1> command = null; public Handler(Lambda<T1> condition, Lambda<T1> command) { this.lambda = condition; this.command = command; } public boolean handle(T1 request) { if (lambda.lambda(request)) command.lambda(request); return lambda.lambda(request); } } public static abstract class Lambda<T1>{ public abstract Boolean lambda(T1 request); } } class TestChainOfResponsibility { public static void main(String[] args) { new TestChainOfResponsibility().test(); } private void test() { new Chain(new Handler[]{ // chain of responsibility new Handler<Request>( new Lambda<Request>(){ // command public Boolean lambda(Request condition) { return condition.getValue() >= 600; } }, new Lambda<Request>(){ public Boolean lambda(Request command) { System.out.println("You are rich: " + command.getValue() + " (id: " + command.hashCode() + ")"); return true; } } ), new Handler<Request>( new Lambda<Request>(){ public Boolean lambda(Request condition) { return condition.getValue() >= 100; } }, new Lambda<Request>(){ public Boolean lambda(Request command) { System.out.println("You are poor: " + command.getValue() + " (id: " + command.hashCode() + ")"); return true; } } ), }, new Request[]{ new Request().setValue(600), // chaining method new Request().setValue(100), } ).start(); } }

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• Can protobuf-net serialize this combination of interface and generic collection?

  - by tsupe

  I am trying to serialize a ItemTransaction and protobuf-net (r282) is having a problem. ItemTransaction : IEnumerable<KeyValuePair<Type, IItemCollection>></code> and ItemCollection is like this: FooCollection : ItemCollection<Foo> ItemCollection<T> : BindingList<T>, IItemCollection IItemCollection : IList<Item> where T is a derived type of Item. ItemCollection also has a property of type IItemCollection. I am serializing like this: IItemCollection itemCol = someService.Blah(...); ... SerializeWithLengthPrefix<IItemCollection>(stream, itemCol, PrefixStyle.Base128); My eventual goal is to serialize ItemTransaction, but am snagged with IItemCollection. Item and it's derived types can be [de]serialized with no issues, see [1], but deserializing an IItemCollection fails (serializing works). ItemCollection has a ItemExpression property and when deserializing protobuf can't create an abstract class. This makes sense to me, but I'm not sure how to get through it. ItemExpression<T> : ItemExpression, IItemExpression ItemExpression : Expression ItemExpression is abstract as is Expression How do I get this to work properly? Also, I am concerned that ItemTransaction will fail since the IItemCollections are going to be differing and unknown at compile time (an ItemTransaction will have FooCollection, BarCollection, FlimCollection, FlamCollection, etc). What am I missing (Marc) ? [1] http://stackoverflow.com/questions/2276104/protobuf-net-deserializing-across-assembly-boundaries

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• Graph-structured databases and Php

  - by stagas

  I want to use a graph database using php. Can you point out some resources on where to get started? Is there any example code / tutorial out there? Or are there any other methods of storing data that relate to each other in totally random/abstract situations? - Very abstract example of the relations needed: John relates to Mary, both relate to School, John is Tall, Mary is Short, John has Blue Eyes, Mary has Green Eyes, query I want is which people are related to 'Short people that have Green Eyes and go to School' - answer John - Another example: TrackA -> ArtistA -> ArtistB -> AlbumA -----> [ label ] -> AlbumB -----> [ A ] -> TrackA:Remix -> Genre:House -> [ Album ] -----> [ label ] TrackB -> [ C ] [ B ] Example queries: Which Genre is TrackB closer to? answer: House - because it's related to Album C, which is related to TrackA and is related to Genre:House Get all Genre:House related albums of Label A : result: AlbumA, AlbumB - because they both have TrackA which is related to Genre:House - It is possible in MySQL but it would require a fixed set of attributes/columns for each item and a complex non-flexible query, instead I need every attribute to be an item by itself and instead of 'belonging' to something, to be 'related' to something.

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• Java - Class type from inside static initialization block

  - by DutrowLLC

  Is it possible to get the class type from inside the static initialization block? This is a simplified version of what I currently have:: class Person extends SuperClass { String firstName; static{ // This function is on the "SuperClass": // I'd for this function to be able to get "Person.class" without me // having to explicitly type it in but "this.class" does not work in // a static context. doSomeReflectionStuff(Person.class); // IN "SuperClass" } } This is closer to what I am doing, which is to initialize a data structure that holds information about the object and its annotations, etc... Perhaps I am using the wrong pattern? public abstract SuperClass{ static void doSomeReflectionStuff( Class<?> classType, List<FieldData> fieldDataList ){ Field[] fields = classType.getDeclaredFields(); for( Field field : fields ){ // Initialize fieldDataList } } } public abstract class Person { @SomeAnnotation String firstName; // Holds information on each of the fields, I used a Map<String, FieldData> // in my actual implementation to map strings to the field information, but that // seemed a little wordy for this example static List<FieldData> fieldDataList = new List<FieldData>(); static{ // Again, it seems dangerous to have to type in the "Person.class" // (or Address.class, PhoneNumber.class, etc...) every time. // Ideally, I'd liken to eliminate all this code from the Sub class // since now I have to copy and paste it into each Sub class. doSomeReflectionStuff(Person.class, fieldDataList); } }

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• cannot override a concrete member without a third member that's overridden by both

  - by huynhjl

  What does the following error message mean? cannot override a concrete member without a third member that's overridden by both (this rule is designed to prevent ``accidental overrides''); I was trying to do stackable trait modifications. It's a little bit after the fact since I already have a hierarchy in place and I'm trying to modify the behavior without having to rewrite a lot of code. I have a base class called AbstractProcessor that defines an abstract method sort of like this: class AbstractProcessor { def onPush(i:Info): Unit } I have a couple existing traits, to implement different onPush behaviors. trait Pass1 { def onPush(i:Info): Unit = { ... } } trait Pass2 { def onPush(i:Info): Unit = { ... } } So that allows me to use new AbstractProcessor with Pass1 or new AbstractProcessor with Pass2. Now I would like to do some processing before and after the onPush call in Pass1 and Pass2 while minimizing code changes to AbstractProcessor and Pass1 and Pass2. I thought of creating a trait that does something like this: trait Custom extends AbstractProcessor { abstract override def onPush(i:Info): Unit = { // do stuff before super.onPush(i) // do stuff after } And using it with new AbstractProcessor with Pass1 with Custom and I got that error message.

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• casting Collection<SomeClass> to Collection<SomeSuperClass>

  - by skrebbel

  Hi all, I'm sure this has been answered before, but I really cannot find it. I have a java class SomeClass and an abstract class SomeSuperClass. SomeClass extends SomeSuperClass. Another abstract method has a method that returns a Collection<SomeSuperClass>. In an implementation class, I have a Collection<SomeClass> myCollection I understand that I cannot just return myCollection, because Collection<SomeClass> does not inherit from Collection<SomeSuperClass>. Nevertheless, I know that everything in myCollection is a SomeSuperClass because after all, they're SomeClass objects which extend SomeSuperClass. How can I make this work? I.e. I want public class A { private Collection<SomeClass> myCollection; public Collection<SomeSuperClass> getCollection() { return myCollection; //compile error! } } The only way I've found is casting via a non-generic type and getting unchecked warnings and whatnot. There must be a more elegant way, though? I feel that also using Collections.checkedSet() and friends are not needed, since it is statically certain that the returned collection only contains SomeClass objects (this would not be the case when downcasting instead of upcasting, but that's not what I'm doing). What am I missing? Thanks!

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• Can a class inherit from LambdaExpression in .NET? Or is this not recommended?

  - by d.

  Consider the following code (C# 4.0): public class Foo : LambdaExpression { } This throws the following design-time error: Foo does not implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) There's absolutely no problem with public class Foo : Expression { } but, out of curiosity and for the sake of learning, I've searched in Google System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) and guess what: zero results returned (when was the last time you saw that?). Needless to say, I haven't found any documentation on this method anywhere else. As I said, one can easily inherit from Expression; on the other hand LambdaExpression, while not marked as sealed (Expression<TDelegate> inherits from it), seems to be designed to prevent inheriting from it. Is this actually the case? Does anyone out there know what this method is about? EDIT (1): More info based on the first answers - If you try to implement Accept, the editor (C# 2010 Express) automatically gives you the following stub: protected override Expression Accept(System.Linq.Expressions.ExpressionVisitor visitor) { return base.Accept(visitor); } But you still get the same error. If you try to use a parameter of type StackSpiller directly, the compiler throws a different error: System.Linq.Expressions.Compiler.StackSpiller is inaccessible due to its protection level. EDIT (2): Based on other answers, inheriting from LambdaExpression is not possible so the question as to whether or not it is recommended becomes irrelevant. I wonder if, in cases like this, the error message should be Foo cannot implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) because [reasons go here]; the current error message (as some answers prove) seems to tell me that all I need to do is implement Accept (which I can't do).

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• how do i execute a stored procedure with vici coolstorage?

  - by lincolnk

  I'm building an app around Vici Coolstorage (asp.net version). I have my classes created and mapped to my database tables and can pull a list of all records fine. I've written a stored procedure where the query jumps across databases that aren't mapped with Coolstorage, however, the fields in the query result map directly to one of my classes. The procedure takes 1 parameter. so 2 questions here: how do i execute the stored procedure? i'm doing this CSParameterCollection collection = new CSParameterCollection(); collection.Add("@id", id); var result = Vici.CoolStorage.CSDatabase.RunQuery("procedurename", collection); and getting the exception "Incorrect syntax near 'procedurename'." (i'm guessing this is because it's trying to execute it as text rather than a procedure?) and also, since the class representing my table is defined as abstract, how do i specify that result should create a list of MyTable objects instead of generic or dynamic or whatever objects? if i try Vici.CoolStorage.CSDatabase.RunQuery<MyTable>(...) the compiler yells at me for it being an abstract class.

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• How to create a JAX-RS service where the sub-resource @Path doesn't have a leading slash

  - by Matt

  I've created a JAX-RS service (MyService) that has a number of sub resources, each of which is a subclass of MySubResource. The sub resource class being chosen is picked based on the parameters given in the MyService path, for example: @Path("/") @Provides({"text/html", "text/xml"}) public class MyResource { @Path("people/{id}") public MySubResource getPeople(@PathParam("id") String id) { return new MyPeopleSubResource(id); } @Path("places/{id}") public MySubResource getPlaces(@PathParam("id") String id) { return new MyPlacesSubResource(id); } } where MyPlacesSubResource and MyPeopleSubResource are both sub-classes of MySubResource. MySubResource is defined as: public abstract class MySubResource { protected abstract Results getResults(); @GET public Results get() { return getResults(); } @GET @Path("xml") public Response getXml() { return Response.ok(getResults(), MediaType.TEXT_XML_TYPE).build(); } @GET @Path("html") public Response getHtml() { return Response.ok(getResults(), MediaType.TEXT_HTML_TYPE).build(); } } Results is processed by corresponding MessageBodyWriters depending on the mimetype of the response. While this works it results in paths like /people/Bob/html or /people/Bob/xml where what I really want is /people/Bob.html or /people/Bob.xml Does anybody know how to accomplish what I want to do?

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• Java generic Comparable where subclasses can't compare to eachother

  - by dege

  public abstract class MyAbs implements Comparable<MyAbs> This would work but then I would be able to compare class A and B with each other if they both extend MyAbs. What I want to accomplish however is the exact opposite. So does anyone know a way to get the generic type to be the own class? Seemed like such a simple thing at first... Edit: To explain it a little further with an example. Say you have an abstract class animals, then you extend it with Dogs and ants. I wouldn't want to compare ants with Dogs but I however would want to compare one dog with another. The dog might have a variable saying what color it is and that is what I want to use in the compareTo method. However when it comes to ants I would rather want to compare ant's size than their color. Hope that clears it up. Could possibly be a design flaw however.

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