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• Programming tutorials for people with zero experience

  - by www.aegisub.net

  A friend of mine is interested in learning how to program computers, but she knows nothing about programming. I suggested that Python might be a good language to start with, but after some googling, I couldn't find any tutorials that covered both programming and Python in an adequate way. I don't want her to go through the tiresome "learn algorithms in pseudocode first" routine. Instead, I'd like a tutorial that will explain the basic ideas while working towards a real goal, e.g. a very simple console game. Does anyone know of any such tutorials? Do you think that I'm mistaken in how I'm handling this? Is Python a bad choice? I know that something like C, C++ or Java won't work - too many details will be very counterproductive. On the other hand, I think that Lisp might be too mathematical and abstract. Python, on the other hand, will let her even do something like coding primitive graphical games in a short period of time.

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• using partials in view helpers

  - by takeshin

  Creating custom Zend View helpers I often end up with something like: // logic here if ($condition) { $output = <<<EOS... } else { $output = <<<EOS... } or using switch. Then to eliminate this, I create setPartial(), getPartial() and htmlize() for using external .phtml's. This is not the best solution, because partials do not support doctype changing. Is there any better solution, than creating abstract class handling this common case? Are there any ready Zend solutions for this case? Separate view helper for each case? And where to put common code?

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• Keyboard not responding on startup

  - by Mestika

  I’m having a weird problem with one of the laptops at my work. Every now and then (not a systematic repeating pattern, but kind of random) the keyboard will not function on start up. The computer boots and it gets to the CTRL + ALT + DELETE screen and it is responding to nothing from the keyboard. The mouse works fine. I then try to force a shutdown and reboot the machine and most of the time it then works. My first thought was that it was a hardware malfunction with the keyboard hardware but it seems strange that the computer can be stationed for several days without being removed and it still “loses” connection to the keyboard. The OS is Windows 7 Pro and it is a Dell Laptop Vostro. Does anyone experienced this kind of problem with a laptop with/with out Windows 7 and maybe got a solution to the problem?

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• Why Is It That Generics Constraint Can't Be Casted to Its Derived Type?

  - by Ngu Soon Hui

  It is quite puzzling to find out that Generics Constraint Can't Be Casted to Its Derived Type. Let's say I have the following code: public abstract class BaseClass { public int Version { get { return 1; } } public string FixString { get; set; } public BaseClass() { FixString = "hello"; } public virtual int GetBaseVersion() { return Version; } } public class DeriveClass: BaseClass { public new int Version { get { return 2; } } } And guess what, this method will return a compilation error: public void FreeConversion<T>(T baseClass) { var derivedMe = (DeriveClass)baseClass; } I would have to cast the baseClass to object first before I can cast it to DerivedClass. Seems to me pretty ugly. Why this is so?

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• Fluent NHibernate ExportSchema without connexion string

  - by Vince

  Hi all, I want to propose to user a way to generate database table script creation. To do this for now i use NHibernate ExportSchema bases on a NHibernate configuration generated with Fluent NHibernate this way (during my ISessionFactory creation method): FluentConfiguration configuration = Fluently.Configure(); ... Mapping conf ... configuration.Database(fluentDatabaseProvider); this.nhibernateConfiguration = configuration.BuildConfiguration(); returnSF = configuration.BuildSessionFactory(); ... Later new SchemaExport(this.nhibernateConfiguration) .SetOutputFile(filePath) .Execute(false, false, false); fluentDatabaseProvider is a FluentNHibernate IPersistenceConfigurer which is needed to get proper sql dialect for database creation. When factory is created with an existing database, everything works fine. But what i want to do is to create an NHibernate Configuration object on a selected database engine without a real database behind the scene... And i don't manage to do this. If anybody has some idea.

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• what else to do to establish many-to-many associations in Ruby on Rails? thanks!

  - by john

  Hi, I have two classes and I want to establish a many-to-many assications, here is the code: class Category < ActiveRecord::Base has_and_belongs_to_many :events has_and_belongs_to_many :tips end class Tip < ActiveRecord::Base has_and_belongs_to_many :categories However, I kept getting the following errors and I would appreciate it if some one could educate me what is going wrong: PGError: ERROR: relation "categories_tips" does not exist : SELECT "categories".id FROM "categories" INNER JOIN "categories_tips" ON "categories".id = "categories_tips".category_id WHERE ("categories_tips".tip_id = NULL ) the viewer part: 4: <%= text_field :tip, :title %></label></p> 5: 6: <p><label>Categories<br/> 7: <%= select_tag('categories[]', options_for_select(Category.find(:all).collect {|c| [c.name, c.id] }, @tip.category_ids), :multiple => true ) %></label></p> 8: 9: <p><label>Location<br/> 10: <%= text_field_with_auto_complete :tip, :abstract %></label></p>

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• Deserialising Json to derived types in Asp.Net Web API

  - by IoChaos

  I'm calling a method of my WebAPI sending a json that I would like to match (or bind) with a model. In the controller I have a method like: public Result Post([ModelBinder(typeof(CustomModelBinder))]MyClass model); 'MyClass', wich is given as a parameter is an abstract class. I would like that at, depending of the type of json passed, the correct inherited class is instantiated. To achieve it, I'm trying to implement a custom binder. The problem is that (I don't know if it's very basic but I can't find anything) I don't know how to retrieve the raw Json (or better, some kind of serialization) that comes in the request. I see: actionContext.Request.Content But all methods are exposed as async. I don't know who this fits with passing the generate model to the controller method... Thanks a lot!

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• Inheriting database connection in PHP OOP

  - by vrode

  My abstract class Database is made for database interaction and any child of this class (UserDatabase, ActionDatabase, EventDatabase) inherits its database connection which is defined as static. `abstract class Database { static $connection = mysql_connect( ); } class UserDatabase extends Database { ... public function __construct( ) { $connection ? "connected" : "not connected"; $this-table = "users"; mysql_query( "FROM " . $this-table . " SELECT *" ); } } ` Does that mean, that my database connection is only set up and stored in memory once and passed on to subclasses as reference without being replicated for each instance? Is this how you would implement you OOP-correct database interface?

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• Programming Quiz [closed]

  - by arin-s-rizk

  Hi one of my mates sent me this quiz see if you can guess the answers I will post mine later. In this quiz, some tasks related to the compilation process are listed. For each one of them, specify the part of the compiler that is responsible of performing it. Here are the possible answers: Lexical analyzer Parser Semantic analyzer None of the above Just fill the right choice (the number only) in the blank after each task: Checking that the parentheses in an expression are balanced _ _ _ _ _ Removing comments from the program _ _ _ _ _ Grouping input characters into "tokens" _ _ _ _ _ Reporting an error to the programmer about a missing (;) at the end of a C++ statement _ _ _ _ _ Checking if the type of the RHS (Right-Hand Side) of an assignment (=) is compatible with the LHS (Left-Hand Side) variable _ _ _ _ _ Converting the (AST) Abstract Syntax Tree into machine language _ _ _ _ _ Reporting an error about a strange character like '^' in a C++ program _ _ _ _ _ Optimizing the AST _ _ _ _ _

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• Fluent NHibernate + multiple databases

  - by Pablote

  My project needs to handle three databases, that means three session factories. The thing is if i do something like this with fluent nhibernate: .Mappings(m = m.FluentMappings.AddFromAssembly(Assembly.GetExecutingAssembly())) the factories would pick up all the mappings, even the ones that correspond to another database I've seen that when using automapping you can do something like this, and filter by namespace: .Mappings(m = m.AutoMappings.Add(AutoMap.AssemblyOf().Where(t = t.Namespace == "Storefront.Entities"))) I havent found anything like this for fluent mappings, is it possible?? The only solutions I can think of are: either create separate assemblies for each db mapping classes or explicitly adding each of the entities to the factory configuration. I would prefer to avoid both, if possible. Thanks.

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• MyFaces Test Framework not working with JSF 2.1

  - by Karl Kildén

  we have a lot of tests that uses Myfaces Test Framework for JSF 2.0. http://myfaces.apache.org/test/index.html Problem is we can't get it to work with JSF 2.1. Does anyone know a workaround or a way to solve this? When we run the tests we get the following error: java.lang.IllegalStateException: Application was not properly initialized at startup, could not find Factory: javax.faces.application.ApplicationFactory It works fine with jsf 2.0 though. A typical use case in our code: // code block; assertFalse("Error message not expected. ", facesContext .getMessages().hasNext()); JSF 2.1 has a few syntax changes so my guess would be that's the problem.

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• "Overriding" instance variables in subtype: Possible risks?

  - by sebastiangeiger

  Say I had a class SuperClass and two subclasses SubClassA and SubClassB that inherit from SuperClass. abstract class SuperClass{ ... List someList; ... } class SubClassA extends SuperClass{ ... List<String> someList; ... } class SubClassB extends SuperClass{ ... List<Integer> someList; ... } That way it is convenient because I can get someList.size() in Superclass and have Typesafety in the Subclasses. The problem is that it does not "feel" right, can you think of potential hazards this apporach has that I am not aware of?

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• How to get the Host value inside ~/.ssh/config

  - by iconoclast

  Within a ~/.ssh/config or ssh_config file, %h will give you the HostName value, but how do you get the Host ("alias") value? Why would I want to do that? Well, here's an example Host some_host_alias HostName 1.2.3.4 User my_user_name PasswordAuthentication no IdentityFile ~/.ssh/some_host_alias.rsa.id LocalCommand some_script.sh %h # <---- this is the critical line If I pass %h to the script, then it uses 1.2.3.4, which fails to give it all the options it needs to connect to that machine. I need to pass some_host_alias, but I can't find the % variable for that. (And: yes! I'm aware of the risk of recursion. That's solved inside the script.) UPDATE: Kenster pointed out that I could just hard-code the Host value as an argument to the script. Of course this will work in the example I gave, but it won't work if I'm using pattern matching for the Host.

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• Using FieldSelector when searching with Lucene

  - by Christian

  I'm searching articles in PubMed via Lucene. Each of the 20,000,000 articles has an abstract with ~250 words and an ID. At the moment I store my searches, with each take multiple seconds, in a TopDocs object. Searchs can find thousands of articles. I'm just interested in the ID of the article. Does Lucene load the abstracts internally into the TopDocs? If so can I prevent that behavior through FieldSelectors or do FieldSelectors only work with IndexReader and don't work with IndexSearcher?

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• is right to implement a business logic in the type binding DI framwork?

  - by Martino

  public IRedirect FactoryStrategyRedirect() { if (_PasswordExpired) { return _UpdatePasswordRedirectorFactory.Create(); } else { return _DefaultRedirectorFactory.Create(); } } This strategy factory method can be replaced with type binding and when clause: Bind<IRedirect>.To<UpdatePasswordRedirector>.When(c=> c.kernel.get<SomeContext>().PasswordExpired()) Bind<IRedirect>.To<DefaultRedirector>.When(c=> not c.kernel.get<SomeContext>().PasswordExpired()) I wonder which of the two approaches is the more correct. What are the pros and cons. Especially in the case in which the logic is more complex with more variables to test and more concrete classes to return. is right to implement a business logic in the binding?

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• How to peform an external request in Kohana 3?

  - by alex

  I've always used cURL for this sort of stuff, but this article got me thinking I could request another page easily using the Request object in Kohana 3. $url = 'http://www.example.com'; $update = Request::factory($url); $update->method = 'POST'; $update->post = array( 'key' => 'value' ); $update->execute(); echo $update->response; However I get the error Accessing static property Request::$method as non static From this I can assume it means that the method method is static, but that doesn't help me much. I also copied and pasted the example from that article and it threw the same error. Basically, I'm trying to POST to a new page on an external server, and do it the Kohana way. So, am I doing this correctly, or should I just use cURL (or file_get_contents() with context)?

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• Refactoring common method header and footer

  - by David Wong

  I have the following chunk of header and footer code appearing in alot of methods. Is there a cleaner way of implementing this? Session sess = factory.openSession(); Transaction tx; try { tx = sess.beginTransaction(); //do some work ... tx.commit(); } catch (Exception e) { if (tx!=null) tx.rollback(); throw e; } finally { sess.close(); } The class in question is actually an EJB 2.0 SessionBean which looks like: public class PersonManagerBean implements SessionBean { public void addPerson(String name) { // boilerplate // dostuff // boilerplate } public void deletePerson(Long id) { // boilerplate // dostuff // boilerplate } }

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• WPF: Creating instances of resources?

  - by oakskc

  I'm brand spanking new to WPF and am trying to play around with projects to better understand what I'm reading. My understanding of a resource is that it is the instance, you can't use it like a factory and create instances of it. For example, a XAML-defined rectangle. You can reference it, but you can't have numerous instances of it all over the surface. In WPF, what would be the way to do that? If I define a Rectangle as a resource with specific properties and wanted to have multiple instances of that within a dynamically-generated grid, how should I be going about it? Or is there a different way I should be trying to do this? Purely academic exercise with no real-world application.

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• How to make form validation in Django dynamic?

  - by Oli

  I'm trying to make a form that handles the checking of a domain: the form should fail based on a variable that was set earlier in another form. Basically, when a user wants to create a new domain, this form should fail if the entered domain exists. When a user wants to move a domain, this form should fail if the entered domain doesn't exist. I've tried making it dynamic overload the initbut couldn't see a way to get my passed variabele to the clean function. I've read that this dynamic validation can be accomplished using a factory method, but maybe someone can help me on my way with this? Here's a simplified version of the form so far: #OrderFormStep1 presents the user with a choice: create or move domain class OrderFormStep2(forms.Form): domain = forms.CharField() extension = forms.CharField() def clean(self): cleaned_data = self.cleaned_data domain = cleaned_data.get("domain") extension = cleaned_data.get("extension") if domain and extension: code = whoislookup(domain+extension); #Raise error based on result from OrderFormStep1 #raise forms.ValidationError('error, domain already exists') #raise forms.ValidationError('error, domain does not exist') return cleaned_data

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• Needs opinions based on design guidelines .

  - by Abu Hamzah

  i am in the process of desigining my domain model and i know its very hard to suggest without knowledge of domain but what i am asking is how to implement or the best way of implementing the baseclass in my domain model. here are few classes: PartialPerson.cs Facilities.cs Visit.cs EntryPoint.cs etc.... my baseclass looks like this: public abstract class BaseClass { public int InfoId { get; } public int PersonId { get; } } here is what i am confused and need help. how do i implement the above baseclass? in the PartialPerson,Facilities,Visit...

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• Managing memory of polymorphic timed events with DLL

  - by Milo

  Here is my issue. My Gui library that I made supports timed events. Basically, I have a class called TimedEvent which users inherit from. They then do: addTimedEvent(new DerivedTimedEvent(...)); However given the nature of timed events, I manage the memory afterwards. So when the timed event has done its thing, my library calls delete on it. Although it runs fine, that is because the exe and the library were both built with msvc 2008. I think I might have trouble if I have 2 versions of the runtime, one for the lib, and one for the exe. What can I do to fix this? I can't create a factory because the derived type is on the exe side of things. I also cannot ask the user to call delete since they might not have a way to keep track of time, or know if the event was delayed for whatever reason. Thanks

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• How to optimize indexing of large number of DB records using Zend_Lucene and Zend_Paginator

  - by jdichev

  So I have this cron script that is deployed and ran using Cron on a host and indexes all the records in a database table - the index is later used both for the front end of the site and the backed operations as well. After the operation, the index is about 3-4 MB. The problem is it takes a lot of resources (CPU: 30+ and a good chunk of memory) and slows the machine down. My question is about how to optimize the operation described below: First there is a select query built using the Zend Framework API, this query is then passed to a Paginator factory that returns a paginator which I am using to balance the current number of items being indexed and not iterate over too much items. The script is iterating over the current items in the paginator object using a foreach loop until reaching the end and then it starts from the beginning after getting items for the next page. I am suspecting this overhead is caused by the Zend_Lucene but no idea how this could be improved.

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• Table per subclass inheritance relationship: How to query against the Parent class without loading a

  - by Arthur Ronald F D Garcia

  Suppose a Table per subclass inheritance relationship which can be described bellow (From wikibooks.org - see here) Notice Parent class is not abstract @Entity @Inheritance(strategy=InheritanceType.JOINED) public class Project { @Id private long id; // Other properties } @Entity @Table(name="LARGEPROJECT") public class LargeProject extends Project { private BigDecimal budget; } @Entity @Table(name="SMALLPROJECT") public class SmallProject extends Project { } I have a scenario where i just need to retrieve the Parent class. Because of performance issues, What should i do to run a HQL query in order to retrieve the Parent class and just the Parent class without loading any subclass ???

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• Create Class objects based on type signature

  - by Andreas_D

  Class.forName(boolean.class.getName()); This doesn't work in Java - the virtual machine slaps you with a ClassNotFoundException. I was in need for something like that because I wanted to reflect methods based on Strings that included the method signatures, like public void doSomething(boolean yesWeCan, java.lang.String[] presidents); At the end I came up with a custom 'ClassFactory' which translates the type Strings to class objects. This factory includes a lot of handlers for primitive and array type values. The handler for array type objects is something like: if (isArrayOfObjects) { return Class.forName("L["+typeName.replace("[]", "")+";"); } My question is - have I missed something in the Java 1.5+ API that might do the trick?

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• Validates presence of each other in two associated models

  - by Sergey Alekseev

  I have the following two models: class Parent < ActiveRecord::Base has_one :child, dependent: :destroy validates :child, presence: true end class Child < ActiveRecord::Base belongs_to :parent validates :parent, presence: true end I want to create Parent object. If I do the following: Parent.create! or Factory(:parent) Exception raises: ActiveRecord::RecordInvalid: Validation failed: Child can't be blank But I can't create Child object without Parent object for the same reason - I need to create Parent object first in order to pass presence validation. As it appears I have some kind of infinite recursion here. How to solve it?

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