specification-pattern

So, I've looked at some posts about the Specification Pattern here, and haven't found an answer to this one yet. My question is, in an n-layered architecture, where exactly should me Specifications get "newed" up? I could put them in my Service Layer (aka, Application layer it's sometimes called... basically, something an .aspx code-behind would talk to), but I feel like by doing that, I'm letting business rules leak out of the Domain. If the Domain objects are accessed some other way (besides the Service Layer), the Domain objects cannot enforce their own business rules. I could inject the

I have to implement certain business rules with hundreds of lines of below code if this then this else if then this . . // hundreds of lines of rules else that Do we have any design pattern which can effectively implement this or reuse the code so that it can be applied to all different rules. I heard of Specification Pattern which creates something like below public interface Specification { boolean isSatisfiedBy(Object o); Specification and(Specification specification); Specification or(Specification specification); Specification not(Specification specification); } public abstract class

After reading a series of blogs ( here and here ) by Chris Missal from LosTechies.com on the Specification Pattern I am am really interested in finding more complete examples. Does anyone know where I could find a more fleshed out example or perhaps an open source project that uses this pattern? Also take a look at the Dimecasts 'Learning the Specification pattern' for a walkthrough of an example. Having learned the Specification pattern through the same blogs as you listed, I'm not yet convinced. It could just be that the examples are too simplistic so it seems more work that it's worth. A

I've been searching for quite some time for a good solution to the problems presented by the typical Repository pattern (growing list of methods for specialized queries, etc.. see: http://ayende.com/blog/3955/repository-is-the-new-singleton ). I really like the idea of using Command queries, particularly through use of the Specification pattern. However, my problem with specification is that it only relates to the criteria of simple selections (basically, the where clause), and does not deal with the other issues of queries, such as joining, grouping, subset selection or projection, etc..

I would like to delete collumns with a specific string "Gtype." from a .txt tab delimited file. I already have tried this command in R: df <- df[, -grep("GType.", colnames(df))] to do this task. However my matrix is too big (more than 13 GB), and R cannot deal with it. (Error: cannot allocate vector of size....) My input file: Log.NE122 Gtype.NE122 Log.NE144 Gtype.NE144 -0.33 AA 1.0 AB My expected output: Log.NE122 Log.NE144 -0.33 1.0 I am wondering that it works in bash. If someone have other options.... Using awk: awk 'NR==1{for (i=1; i<=NF; i++) if ($i ~ /Gtype/) a[i]; else printf "%s%s",

This question is an enhancement to the already answered question How to apply multiple filter conditions (simultaneously) on a list? In the above mentioned question we have a method that applied AND operator on all the specifications. This is achieved by using LINQ All operator on the specifications. public static List<Product> GetProductsUisngAndFilters(List<Product> productList, List<Specification<Product>> productSpecifications) { return productList.Where(p => productSpecifications.All(ps => ps.IsSatisfiedBy(p))).ToList(); } We need to create a new method (GetProductsUisngDynamicFilters)

I use spring data and the JpaSpecificationExecutor::findAll method to fetch my models. How I could use query hints when calling this method? The above source code works fine but I can't set QueryHint for my JPA provider (in my case EclipseLink). @Repository public interface ProductRepository extends JpaRepository<Product, Integer>, JpaSpecificationExecutor<Product> { } @Service public class ProductService { @Autowired private ProductRepository productRepository; public List<Product> findByTitle(String locale, String titleToSearch) { return productRepository.findAll((Root<ProductCategory> root,