I'm starting on a Scala application which uses Hibernate (JPA) on the back end. In order to load an object, I use this line of code: val addr = s.load(classOf[Address], addr_id).asInstanceOf[Address]; Needless to say, that's a little painful. I wrote a helper class which looks like this: import org.hibernate.Session class DataLoader...
I'm trying to understand type patterns and generic classes in Haskell but can't seem to get it. Could someone explain it in laymen's terms? In [1] I've read that "To apply functions generically to all data types, we view data types in a uniform manner: except for basic predefined types such as Float, IO, and →, every Haskell data t...
Duplicate: Java generics why this won’t work Duplicate: Instantiating a generic class in Java I would like to create an object of Generics Type in java. Please suggest how can I achieve the same. Note: This may seem a trivial Generics Problem. But I bet.. it is'nt. :) suppose I have the class declaration as: public class...
Sorry guys! i am so into the code! that i forgot to put the compiler errors. Here is a new version of the code simplified! And this are the errors: Error 1 The best overloaded method match for 'IWeird.DataBase.ModifyData(ref IWeird.IDataTable)' has some invalid arguments Error 2 Argument '1': cannot convert from 'ref IWeird.Period...
Would it be possible to do something like the following in c#? Basically TParent and TChildren should be types of the class A but not necessairly have the same types that were passed in. I know this may sound confusing but I want to strongly type the children and parents of a particular object, but at the same time they must be of the sa...
To use such great function as ConvertAll(), I have to convert IList to List, it's painful. ...
Using a reference from... http://weblogs.asp.net/pwelter34/archive/2006/05/03/444961.aspx I have a serializable generic dictionary. One thing I wanted to do is to add the Key into the Attribute nodes of the Values (just because It's how I wanted it formatted). Oftentimes, the Key is just a string. Is there any way to force the class to...
I want to have a generic object that implements an interface. I mean if i have a class A class A<E> { E x; } I want to make sure that x will implement a particular interface(myInterface). In other words, that the type E implements an interface. ...
It appears that CollectionAssert cannot be used with generics. This is super frustrating; the code I want to test does use generics. What am I to do? Write boilerplate to convert between the two? Manually check collection equivalence? This fails: ICollection<IDictionary<string, string>> expected = // ... IEnumerable<ID...
I am extending the ImageBox control from EmguCV. The control's Image property can be set to anything implementing the IImage interface. All of the following implement this interface: Image<Bgr, Byte> Image<Ycc, Byte> Image<Hsv, Byte> Now I want to call the Draw method on the object of the above type (what ever it may be). The probl...
Hi, I'm using a recursive tree of hashmaps, specifically Hashmap map where Object is a reference to another Hashmap and so on. This will be passed around a recursive algorithm: foo(String filename, Hashmap<String, Object> map) { //some stuff here for (Entry<String, Object> entry : map.entrySet()) { //type warning th...
Hi there, a little while ago i was reading an article about a series of class that were created that handled the conversion of strings into a generic type. Below is a mock class structure. Basically if you set the StringValue it will perform some conversion into type T public class MyClass<T> { public string StringValue {get;set;} ...
class Bouncy<T> extends Throwable { } // Error: the generic class Bouncy<T> may not subclass java.lang.Throwable Why doesn't Java support generic Throwables? I realize that type erasure complicates certain things, but obviously Java gets by with a lot already, so why not push it one more notch and allow generic Throwables, with c...
I need to create an parameterless instance for a Generic Class in C#. How to do this. ...
I found strange generics behaviour. In two words - thing I realy want is to use ComplexObject1 in most general way, and the thing I realy missed is why defined generic type(... extends BuisnessObject) is lost. The discuss thread is also awailable in my blog http://pronicles.blogspot.com/2010/03/unexpected-generics-behaviour.html. publi...
Func<a, out b, bool>, just don't compile, how to declare that i want the second parameter be an out one? I want to use it like this: public class Foo() { public Func<a, out b, bool> DetectMethod; } ...
Let's assume that our system can perform actions, and that an action requires some parameters to do its work. I have defined the following base class for all actions (simplified for your reading pleasure): public abstract class BaseBusinessAction<TActionParameters> : where TActionParameters : IActionParameters { protected Base...
I'm trying to understand the constraints on generic type parameters in C#. What is the purpose of the where T : new() constraint? Why would you need to insist that the type argument have a public parameterless constructor? Edit: I must be missing something. The highest rated answer says the public parameterless constructor is necessa...
I have a class with a internal array field. I want to expose this array as a property, such that it maintains as much funtionallity of the orginal array but does not violate encapsulation by exposing the array directly. What are the various methods and pros and cons? I'm thinking specifically about IList<T> or Colleciton<T> ...
Hi Guys I have an object obj that is passed into a helper method. public static MyTagGenerateTag<T>(this HtmlHelper htmlHelper, T obj /*, ... */) { Type t = typeof(T); foreach (PropertyInfo prop in t.GetProperties()) { object propValue = prop.GetValue(obj, null); string stringValue = propValue.ToString(); ...