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• Rails - building an absolute url in a model's virtual attribute without url helper

  - by Nick

  I have a model that has paperclip attachments. The model might be used in multiple rails apps I need to return a full (non-relative) url to the attachment as part of a JSON API being consumed elsewhere. I'd like to abstract the paperclip aspect and have a simple virtual attribute like this: def thumbnail_url self.photo.url(:thumb) end This however only gives me the relative path. Since it's in the model I can't use the URL helper methods, right? What would be a good approach to prepending the application root url since I don't have helper support? I would like to avoid hardcoding something or adding code to the controller method that assembles my JSON. Thank you

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• [C++]Advantage of using a static member function instead of an equivalent non-static member function

  - by jonathanasdf

  I was wondering whether there's any advantages to using a static member function when there is a non-static equivalent. Will it result in faster execution (because of not having to care about all of the member variables), or maybe less use of memory (because of not being included in all instances)? Basically, the function I'm looking at is an utility function to rotate an integer array representing pixel colours an arbitrary number of degrees around an arbitrary centre point. It is placed in my abstract Bullet base class, since only the bullets will be using it and I didn't want the overhead of calling it in some utility class. It's a bit too long and used in every single derived bullet class, making it probably not a good idea to inline. How would you suggest I define this function? As a static member function of Bullet, of a non-static member function of Bullet, or maybe not as a member of Bullet but defined outside of the class in Bullet.h? What are the advantages and disadvantages of each?

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• Fastest method for SQL Server inserts, updates, selects from C# ASP.Net 2.0+

  - by Ian

  Hi All, long time listener, first time caller. I use SPs and this isn't an SP vs code-behind "Build your SQL command" question. I'm looking for a high-throughput method for a backend app that handles many small transactions. I use SQLDataReader for most of the returns since forward only works in most cases for me. I've seen it done many ways, and used most of them myself. Methods that define and accept the stored procedure parameters as parameters themselves and build using cmd.Parameters.Add (with or without specifying the DB value type and/or length) Assembling your SP params and their values into an array or hashtable, then passing to a more abstract method that parses the collection and then runs cmd.Parameters.Add Classes that represent tables, initializing the class upon need, setting the public properties that represent the table fields, and calling methods like Save, Load, etc I'm sure there are others I've seen but can't think of at the moment as well. I'm open to all suggestions.

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• Fastest method for SQL Server inserts, updates, selects

  - by Ian

  I use SPs and this isn't an SP vs code-behind "Build your SQL command" question. I'm looking for a high-throughput method for a backend app that handles many small transactions. I use SQLDataReader for most of the returns since forward only works in most cases for me. I've seen it done many ways, and used most of them myself. Methods that define and accept the stored procedure parameters as parameters themselves and build using cmd.Parameters.Add (with or without specifying the DB value type and/or length) Assembling your SP params and their values into an array or hashtable, then passing to a more abstract method that parses the collection and then runs cmd.Parameters.Add Classes that represent tables, initializing the class upon need, setting the public properties that represent the table fields, and calling methods like Save, Load, etc I'm sure there are others I've seen but can't think of at the moment as well. I'm open to all suggestions.

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• Code doesn't work in foreach

  - by Arlen Beiler

  Here is my code: var divarray = document.getElementById("yui-main").getElementsByTagName("div"); var articleHTML; var absHTML; var keyHTML; var bodyHTML = []; for( var i in divarray) { if(divarray[i].className == "articleBody"){ articleHTML = divarray[i]; for( var j in articleHTML ){ bodyHTML[i] = ''; if(articleHTML[j].className == "issueMiniFeature"){continue;} if(articleHTML[j].className == "abstract"){absHTML = articleHTML[i]; continue;} if(articleHTML[j].className == "journalKeywords"){keyHTML = articleHTML[i]; continue;} bodyHTML[i] = articleHTML[i]; } break; } i++; } The error I am getting is: SyntaxError: Unexpected token var I am using Google Chrome

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• How to declare a generic constraint that is a generic type

  - by HackedByChinese

  I have a two generic abstract types: Entity and Association. Let's say Entity looks like this: public class Entity<TId> { //... } and Association looks like this: public class Association<TEntity, TEntity2> { //... } How do I constrain Association so they can be of any Entity? I can accomplish it by the following: public class Association<TEntity, TId, TEntity2, TId2> where TEntity : Entity<TId> where TEntity2: Entity<TId2> { //... } This gets very tedious as more types derive from Association, because I have to keep passing down TId and TId2. Is there a simpler way to do this, besides just removing the constraint?

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• How to achieve table like rows within container using CSS

  - by Barry

  I'm helping an artist maintain her website and have inherited some pretty outdated code. Have moved lots of redundant common code to include files and am now working on moving from inline styles to more CSS-driven styles. For the gallery pages, e.g. http://artistsatlaketahoe.com/abstract.html, a lot of inline styling is used to force the current layout. My preference would be to replace this entirely with CSS that presents the following table-like layout within the "content" div: [image] [image descriptives and purchase button] [image] [image descriptives and purchase button] [image] [image descriptives and purchase button] I'd like to middle-align the image descriptives & purchase button relative to the image if possible. And then apply some padding above and below each row to stop using tags for vertical spacing. Any ideas how to create a div that I can use to get this kind of layout? Thanks!

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• Use delegate for Projection in Linq to SQL

  - by Redeemed1

  I have code something like this in an IRepository implementation in Linq to Sql: var newlist = from h in list where h.StringProp1 == "1" select new MyBusinessBO{ firstProp = h.StringProp1, secondProp = h.StringProp2 }; The projection into MyBusinessBO is not difificult but when the Business Object has many properties the projection code becomes very lengthy. Also, as the projection can occur in several places in the Repository we break the DRY principle. Is there any way to abstract out the projection or replace it with a delegate? I.e. replace the code firstProp = h.StringProp1, secondProp = h.StringProp2 with something reusable?

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• Learning C++ from scratch in Visual Studio?

  - by flesh

  I need to get up to speed with C++ quite quickly (I've never used it previously) - is learning through Visual Studio (i.e. Managed C++) going to be any use? Or will I end up learning the extensions and idiosyncracies of C++ in VS, rather then the language itself? If learning in VS is not recommended, what platform / IDE do you guys suggest? Edit: Can anyone elaborate on what VS will hide or manage for me when coding unmanaged C++? I really need to be learning things like pointers, garbage collection and all the nuts and bolts of the low level language.. does VS abstract or hide any of this kind of stuff from you? Thanks for all the suggestions..

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• Nested class with hidden constructor impossible in c#?

  - by luckyluke

  I' ve been doing some programming lately and faced an issue which i found weird in c#. (at least for me) public class Foo { //whatever public class FooSpecificCollection : List<Bar> { //implementation details } public FooSpecificCollection GetFoosStuff() { //return the collection } } I want the consumer of Foo to be able to obtain a reference to FooSpecificCollection, even perform some operations on it. Maybe even set it to some other property of Foo or smth like that, but not To be able to CREATE an instance of this class. (the only class that should be able to instatiate this collection should be Foo. Is my request really that far-fetched? I know that people way smarter defined c# but shouldn't there be such an option that a parent class can create a nested class instance but nobody else can't. So far I created a solution to make an abstract class, or interface available through the property and implement a concrete private class that is not available anywhere else. Is this a correct way to handle such a situation.?

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• Is it possible to create a domain model for legacy code without refactoring?

  - by plaureano

  I currently have a client that wants me to 'abstract' out a domain model from the existing code but they specifically said that I shouldn't refactor the existing code itself. My question is 1) whether or not this is advisable and 2) what techniques would you apply in this scenario if you can't refactor the code yet they expect you to come up with a model for it? (EDIT: I can't quite put my finger on it, but somehow, not being able to refactor in this case just feels wrong. Has anyone else run into this type of scenario?)

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• C# BinarySearch breaks when inheriting from something that implements IComparable<T>?

  - by Ender

  In .NET the BinarySearch algorithm (in Lists, Arrays, etc.) appears to fail if the items you are trying to search inherit from an IComparable instead of implementing it directly: List<B> foo = new List<B>(); // B inherits from A, which implements IComparable<A> foo.Add(new B()); foo.BinarySearch(new B()); // InvalidOperationException, "Failed to compare two elements in the array." Where: public abstract class A : IComparable<A> { public int x; public int CompareTo(A other) { return x.CompareTo(other.x); } } public class B : A {} Is there a way around this? Implementing CompareTo(B other) in class B doesn't seem to work.

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• creative way for implementing Data object with it's corespanding buisness logic class in java

  - by ekeren

  I have a class that need to be serialized (for both persistentcy and client-server communication) for simplicity reasons lets call the classes Business a BusinessData and I prefix for their Interfaces. All the getter and setter are delegated from Business class to BusinessData class. I thought about implementing IBusinessData interface that will contain all the getter and setters and IBusiness interface that will extend it. I can either make Business extend BuisnessData so I will not need to implement all getter and setter delegates, or make some abstract class ForwardingBusinessData that will only delegate getter and setters. Any of the above option I loose my hierarchy freedom, does any of you have any creative solution for this problem... I also reviewed DAO pattern: http://java.sun.com/blueprints/patterns/DAO.html

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• Extract Generic types from extended Generic

  - by Brigham

  I'm trying to refactor a class and set of subclasses where the M type does extend anything, even though we know it has to be a subclass of a certain type. That type is parametrized and I would like its parametrized types to be available to subclasses that already have values for M. Is there any way to define this class without having to include the redundant K and V generic types in the parameter list. I'd like to be able to have the compiler infer them from whatever M is mapped to by subclasses. public abstract class NewParametrized<K, V, M extends SomeParametrized<K, V>> { public void someMethodThatTakesKAndV(K k1, V v1) { } } In other words, I'd like the class declaration to look something like: public class NewParametrized<M extends SomeParametrized<K, V>> { And K and V's types would be inferred from the definition of M.

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• Static nested class visibility issue with Scala / Java interop

  - by Matt R

  Suppose I have the following Java file in a library: package test; public abstract class AbstractFoo { protected static class FooHelper { public FooHelper() {} } } I would like to extend it from Scala: package test2 import test.AbstractFoo class Foo extends AbstractFoo { new AbstractFoo.FooHelper() } I get an error, "class FooHelper cannot be accessed in object test.AbstractFoo". (I'm using a Scala 2.8 nightly). The following Java compiles correctly: package test2; import test.AbstractFoo; public class Foo2 extends AbstractFoo { { new FooHelper(); } } The Scala version also compiles if it's placed in the test package. Is there another way to get it to compile?

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• Lackadaisical One-to-One between Char and Byte Streams

  - by Vaibhav Bajpai

  I expected to have a one-to-one correspondence between the character streams and byte streams in terms of how the classes are organized in their hierarchy. FilterReader and FilterWriter (character streams) correspond back to FilterInputStream and FilterOutputStream (byte stream) classes. However I noticed few changes as - BufferedInputStream extends FilterInputStream, but BufferedReader does NOT extend FilterReader. BufferedOutputStream and PrintStream both extend FilterOutputStream, but BufferedWriter and PrintWriter does NOT extend FilterWriter. FilterInputStream and FilterOutputStream are not abstract classes, but FilterReader and FilterWriter are. I am not sure if I am being too paranoid to point out such differences, but was just curious to know if there was design reasoning behind such decision.

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• Vendor neutral SQL

  - by Sparafusile

  I'm currently working on a project for a web application that may be installed on several different servers with various software configurations. I want to make my application as flexible as possible by allowing the user to have various SQL servers installed. The problem is the SQL syntax used by any two server vendors does not match up. For a simple example, here is the same SELECT statement for MS SQL and MySQL: MS SQL - SELECT TOP 1 * FROM MyTable ORDER BY DateCreated DESC MySQL - SELECT * FROM MyTable ORDER BY DateCreated DESC LIMIT 1 Are there any standard way to abstract the statement creation for various vendors? Any online resources or books discussing this problem? Any hints or smart-alec remarks that I'd find useful? Further information: I'm writing my we application in vanilla ASP running on a Windows server. Thanks, Spara

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• How to handle JPA annotations for a pointer to a generic interface

  - by HDave

  I have a generic class that is also a mapped super class that has a private field that holds a pointer to another object of the same type: @MappedSuperclass public abstract class MyClass<T extends MyIfc<T>> implements MyIfc<T> { @OneToOne() @JoinColumn(name = "previous", nullable = true) private T previous; ... } My problem is that Eclipse is showing an error in the file at the OneToOne "Target Entity "T" for previous is not an Entity." All of the implementations of MyIfc are, in fact, Entities. I should also add that each concrete implementation that inherit from MyClass uses a different value for T (because T is itself) so I can't use the "targetEntity" attribute. I guess if there is no answer then I'll have to move this JPA annotation to all the concrete subclasses of MyClass. It just seems like JPA/Hibernate should be smart enough to know it'll all work out at run-time. Makes me wonder if I should just ignore this error somehow.

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• Java: Stopping a thread that has run for too long?

  - by Thomas King

  Say I've got something like this public void run(){ Thread behaviourThread = new Thread(abstractBehaviours[i]); behaviourThread.start(); } And I want to wait until abstractBehaviours[i] run method has either finished or run for 5000 milliseconds. How do I do that? behaviourThread.join(5000) doesn't seem to do that afaik (something is wrong with my code and I've put it down to that). All the abstract abstractBehaviour class is of course Runnable. I don't want to implement it inside each run method as that seems ugly and there are many different behaviours, I'd much rather have it in the calling/executing thread and do it just once. Solutions? First time doing something as threaded as this. Thanks!

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• VS compiling Error 1256 ( integer overflow in internal computation ... ) during inheritance

  - by odbb

  Hi there, my problem occurs during compiling Irrlicht3D Engine in VS 2008. 1Error 1256: integer overflow in internal computation due to size or complexity of "irr::IReferenceCounted" I'm currently merging a very old Softwaredriver I have written with the rest of the engine which is much newer. The main Problme is that I have tried to resolve abstract inherince problems. But now I get this error and it is the only one. "irr::IReferenceCounted" is one of the base classes used by other classes which have been inherinced from. What does that mean? I know that an integer overflow can be a normal overflow, but why is this shown during compilation? Any help appreciated! -db

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• advantages of Zend_Db_Table vs raw (My)SQL?

  - by sunwukung

  Currently working on a new Zend application and developing the Model. Having worked with Zend_Db_Table before, I opted to replace references in the Model to the Table API with a custom SQL script to take care of data access duties. Now I'm looking at developing a new application/domain model, and I wanted to get some feedback from people re: their experiences with Zend_Db API vs raw SQL, and use cases where it would be preferable to use the API. From a project perspective, the DB platform is unlikely to change from MySQL - so it doesn't need to be particularly abstract - and I assume writing a custom SQL API will be more performant than the assorted classes the Zend DB API requires.

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• Java/JAXB: Unmarshall Xml to specific subclass based on an attribute

  - by Frothy

  Is it possible to use JAXB to unmarshall xml to a specific Java class based on an attribute of the xml? <shapes> <shape type="square" points="4" square-specific-attribute="foo" /> <shape type="triangle" points="3" triangle-specific-attribute="bar" /> </shapes> I would like to have a List of Shape objects containing a triangle and a square, each with their own shape-specific attribute. IE: abstract class Shape { int points; //...etc } class Square extends Shape { String square-specific-attribute; //...etc } class Triangle extends Shape { String triangle-specific-attribute; //...etc } I'm currently just putting all attributes in one big "Shape" class and it's less than ideal. I could get this to work if the shapes were properly named xml elements, but unfortunately I don't have control of the xml I'm retrieving. Thanks!

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• C# to Java: What is a [DefaultProperty("value")]?

  - by Shiftbit

  I do not understand how the DefaultProperty Metadata tag work or what it signifies. I've read the MSDN and went through the sample but I find it confusing. DefaultPropertyAttribute Class I've read a few blogs and they seem to refer to the indexers. I'm not sure why you would want metadata for your properties? I am coming from a Java background, perhaps a Java analogy would help. [DefaultProperty("Value")] public abstract class FOO<T> : ANY, IBAR<T> { public FOO() { } public FOO(T value) { this.Value = value; } public virtual T Value { get; set; } } Follow up: Property Grid

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• Comparison of collection datatypes in C#

  - by Joel in Gö

  Does anyone know of a good overview of the different C# collection types? I am looking for something showing which basic operations such as Add, Remove, RemoveLast etc. are supported, and giving the relative performance. It would be particularly interesting for the various generic classes - and even better if it showed eg. if there is a difference in performance between a List<T> where T is a class and one where T is a struct. A start would be a nice cheat-sheet for the abstract data structures, comparing Linked Lists, Hash Tables etc. etc. Thanks!

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• Looking for a syntactic shortcut for accessing dictionaries

  - by Sisiutl

  I have an abstract base class that holds a Dictionary. I'd like inherited classes to be able to access the dictionary fields using a convenient syntax. Currently I have lots of code like this: string temp; int val; if (this.Fields.TryGetValue("Key", out temp)) { if (int.TryParse(temp, out val)) { // do something with val... } } Obviously I can wrap this in utility functions but I'd like to have a cool, convenient syntax for accessing the dictionary fields where I can simply say something like: int result = @Key; Is there any way to do something like this in C# (3.5)?

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