Search Results

Search found 18220 results on 729 pages for 'generic programming'.

Page 88/729 | < Previous Page | 84 85 86 87 88 89 90 91 92 93 94 95  | Next Page >

• Using a Type object to create a generic

  - by Richard Neil Ilagan

  Hello all! I'm trying to create an instance of a generic class using a Type object. Basically, I'll have a collection of objects of varying types at runtime, and since there's no way for sure to know what types they exactly will be, I'm thinking that I'll have to use Reflection. I was working on something like: Type elType = Type.GetType(obj); Type genType = typeof(GenericType<>).MakeGenericType(elType); object obj = Activator.CreateInstance(genType); Which is well and good. ^_^ The problem is, I'd like to access a method of my GenericType< instance, which I can't because it's typed as an object class. I can't find a way to cast it obj into the specific GenericType<, because that was the problem in the first place (i.e., I just can't put in something like:) ((GenericType<elType>)obj).MyMethod(); How should one go about tackling this problem? Many thanks! ^_^

  Read the article

• .NET 4.0 Generic Invariant, Covariant, Contravariant

  - by Sameer Shariff

  Here's the scenario i am faced with: public abstract class Record { } public abstract class TableRecord : Record { } public abstract class LookupTableRecord : TableRecord { } public sealed class UserRecord : LookupTableRecord { } public interface IDataAccessLayer<TRecord> where TRecord : Record { } public interface ITableDataAccessLayer<TTableRecord> : IDataAccessLayer<TTableRecord> where TTableRecord : TableRecord { } public interface ILookupTableDataAccessLayer<TLookupTableRecord> : ITableDataAccessLayer<TLookupTableRecord> where TLookupTableRecord : LookupTableRecord { } public abstract class DataAccessLayer<TRecord> : IDataAccessLayer<TRecord> where TRecord : Record, new() { } public abstract class TableDataAccessLayer<TTableRecord> : DataAccessLayer<TTableRecord>, ITableDataAccessLayer<TTableRecord> where TTableRecord : TableRecord, new() { } public abstract class LookupTableDataAccessLayer<TLookupTableRecord> : TableDataAccessLayer<TLookupTableRecord>, ILookupTableDataAccessLayer<TLookupTableRecord> where TLookupTableRecord : LookupTableRecord, new() { } public sealed class UserDataAccessLayer : LookupTableDataAccessLayer<UserRecord> { } Now when i try to cast UserDataAccessLayer to it's generic base type ITableDataAccessLayer<TableRecord>, the compiler complains that it cannot implicitly convert the type.

  Read the article

• Razor support of generic extension methods

  - by Brian

  Hello, With regards to the Razor view engine, say I want to render Html.TextBoxFor<SomeModel>(i => i.Name), it doesn't seem that the inline syntax works as in: @Html.TextBoxFor<SomeModel>(i => i.Name) This doesn't seem to work because it interprets the generic as an HTML tag. I could use a code-block approach, but then what's the best approach to output the content? The HTML string returned from this method, do I response.write it, or is there a syntax for it, or what's the approach? Thanks.

  Read the article

• Generic Abstract Singleton with Custom Constructor in C#

  - by Heka

  I want to write a generic singleton with an external constructor. In other words the constructor can be modified. I have 2 designs in my mind but I don't know whether they are practical or not. First one is to enforce derived class' constructor to be non-public but I do not know if there is a way of it? Second one is to use a delegate and call it inside the constructor? It isn't necessarily to be a constructor. The reason I chose custom constructor is doing some custom initializations. Any suggestions would be appreciated :)

  Read the article

• How can I get the path separator in Perl?

  - by ram

  In case of Java, we can get the path separator using System.getProperty("path.separator"); Is there a similar way in Perl? All I want to do is to find a dir, immediate sub directory. Say I am being given two arguments $a and $b; I am splitting the first one based on the path separator and joining it again except the last fragment and comparing with the second argument. The problem is my code has to be generic and for that I need to know whats the system dependent path separator is?

  Read the article

• Java Webservice with generic methods

  - by danby

  Hi, I was wondering if it is possible to make a generic webservice method in java like this: @WebMethod public <T extends Foo> void testGeneric(T data){ However when I try to consume this with a Java client I get an error stating: [ERROR] Schema descriptor {http://####/}testGeneric in message part "parameters" is not defined and could not be bound to Java. I know it is possible to make a method that takes a parameter such as List and this generates correctly using JAX-WS. I don't mind if there is a solution that means I am tied to using only a particular technology. Thanks, Dan.

  Read the article

• Can I Cast a Generic List by Type??

  - by CrazyJoe

  NavigatorItem NavItem = (NavigatorItem)cboItems.SelectedItem; lblTitle.Text = NavItem.Title; RadWrapPanel Panel = new RadWrapPanel(); Type t = NavItem.ItemsType; //<------ The Type inside my List is here. List<???> items = (List<???>)NavItem.Items; // <----Here Is the problem foreach (object item in items) { Panel.Children.Add((UIElement)Activator.CreateInstance(NavItem.Display,item)); } ItemsContainer.Content = Panel; In code above i need to get the type of items on t variable to put into of my generic List. Help Please!!!

  Read the article

• AutoMapper determine what to map based on generic type

  - by Daz Lewis

  Hi, Is there a way to provide AutoMapper with just a source and based on the specified mapping for the type of that source automatically determine what to map to? So for example I have a type of Foo and I always want it mapped to Bar but at runtime my code can receive any one of a number of generic types. public T Add(T entity) { //List of mappings var mapList = new Dictionary<Type, Type> { {typeof (Foo), typeof (Bar)} {typeof (Widget), typeof (Sprocket)} }; //Based on the type of T determine what we map to...somehow! var t = mapList[entity.GetType()]; //What goes in ?? to ensure var in the case of Foo will be a Bar? var destination = AutoMapper.Mapper.Map<T, ??>(entity); } Any help is much appreciated.

  Read the article

• Autocomplete for generic types in Eclipse

  - by AvrDragon

  "Refer to objects by their interfaces" is a good practise, as mentioned in Effective Java. So for example i prefer List<String> al = new ArrayList<String>(); over ArrayList<String> al = new ArrayList<String>(); in my code. One annoying thing is that if i type ArrayList<String> al = new and then hit Ctrl+Space in Eclipse i get ArrayList<String>() as propostal. But if i type List al = new and then hit Ctrl+Space i will get only propostal to define anonymous inner class, but not propostals such as new ArrayList<String>(), what is 99% the case, or for example new Vector<String>(). Is there any way to get the subclasses as propostals for generic types?

  Read the article

• How can I make this code more generic

  - by Greg

  Hi How could I make this code more generic in the sense that the Dictionary key could be a different type, depending on what the user of the library wanted to implement? For example someone might what to use the extension methods/interfaces in a case where there "unique key" so to speak for Node is actually an "int" not a "string" for example. public interface ITopology { Dictionary<string, INode> Nodes { get; set; } } public static class TopologyExtns { public static void AddNode(this ITopology topIf, INode node) { topIf.Nodes.Add(node.Name, node); } public static INode FindNode(this ITopology topIf, string searchStr) { return topIf.Nodes[searchStr]; } } public class TopologyImp : ITopology { public Dictionary<string, INode> Nodes { get; set; } public TopologyImp() { Nodes = new Dictionary<string, INode>(); } }

  Read the article

• Create instance of generic type in Java?

  - by David Citron

  Is it possible to create an instance of a generic type in Java? I'm thinking based on what I've seen that the answer is "no" (due to type erasure), but I'd be interested if anyone can see something I'm missing: class SomeContainer<E> { E createContents() { return what??? } } EDIT: It turns out that Super Type Tokens could be used to resolve my issue, but it requires a lot of reflection-based code, as some of the answers below have indicated. I'll leave this open for a little while to see if anyone comes up with anything dramatically different than Ian Robertson's Artima Article.

  Read the article

• C# Generic List constructor gives me a MethodAccessException

  - by evilfred

  Hi, I make a list in my code like so: List<IConnection> connections = new List<IConnection>(); where IConnection is my own interface. This is in a .NET 2.0 executable. If I run the code on my machine (with lots of .Net versions installed) it works fine. If I run it on my test machine (which only has .NET 3.5 SP1 installed) then I get a MethodAccessException in the System.Collections.Generic.List constructor. Any ideas what could be going wrong?

  Read the article

• How to get Path Separator in Perl?

  - by ram

  In case of Java, we can get the path separator using System.getProperty("path.separator"); Is there a similar way in Perl? All I want to do is to find a dir, immediate sub directory. Say I am being given two argumens $a and $b; I am splitting the first one based on the path separator and joining it again except the last fragment and comparing with the second argument. The problem is my code has to be generic and for that I need to know whats the system dependent path separator is? Could you help if there is any way to get it? TIA

  Read the article

• Mixing LINQ to SQL with properties of objects in a generic list

  - by BPotocki

  I am trying to accomplish something like this query: var query = from a in DatabaseTable where listOfObjects.Any(x => x.Id == a.Id) select a; Basically, I want to filter the results where a.Id equals a property of one of the objects in the generic list "listOfObjects". I'm getting the error "Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator." Any ideas on how to filter this in an easily readable way using "contains" or another method? Thanks in advance.

  Read the article

• Generic object load function for scala

  - by Isaac Oates

  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(s: Session) { def loadAddress(id: Long): Address = { return s.load(classOf[Address], id).asInstanceOf[Address]; } ... } So, now I can do this: val dl = new DataLoader(s) val addr = dl loadAddress(addr_id) Here's the question: How do I write a generic parametrized method which can load any object using this same pattern? i.e val addr = dl load[Address](addr_id) (or something along those lines.) I'm new to Scala so please forgive anything here that's especially hideous.

  Read the article

• Operator as and generic classes

  - by abatishchev

  I'm writing .NET On-the-Fly compiler for CLR scripting and want execution method make generic acceptable: object Execute() { return type.InvokeMember(..); } T Execute<T>() { return Execute() as T; /* doesn't work: The type parameter 'T' cannot be used with the 'as' operator because it does not have a class type constraint nor a 'class' constraint */ // also neither typeof(T) not T.GetType(), so on are possible return (T) Execute(); // ok } But I think operator as will be very useful: if result type isn't T method will return null, instead of an exception! Is it possible to do?

  Read the article

• Rails: Generic form actions, cancel link losing `:back` on validation failure

  - by Patrick Connor

  I am trying to create a generic set of Submit, Cancel, and Destroy actions for forms. At this point, it appears that everything is working, except that I lose :back functionality then a form reloads due to validation errors. Is there a way to catch the fact that validation has failed, and in that case, keep the request.env['HTTP_REFERER'] or :back value the same without having to edit every controller? = simple_form_for @announcement do |f| = f.error_notification = f.input :message = f.input :starts_at = f.input :ends_at #submit = f.button :submit = "or " = link_to("cancel", url_for(:back)) .right - if !f.object.new_record? - resource = (f.object.class.name).downcase = link_to "destroy", url_for(:action => 'destroy'), :confirm => "Are you sure that you want to delete this #{resource}?", :method => :delete .clear .non_input #post_back_msg #indicator.inline = image_tag "indicator.gif" .inline = "Please wait..." .non_input

  Read the article

• C# Using Reflection to Get a Generic Object's (and its Nested Objects) Properties

  - by Jimbo

  This is a scenario created to help understand what Im trying to achieve. I am trying to create a method that returns the specified property of a generic object e.g. public object getValue<TModel>(TModel item, string propertyName) where TModel : class{ PropertyInfo p = typeof(TModel).GetProperty(propertyName); return p.GetValue(item, null); } The code above works fine if you're looking for a property on the TModel item e.g. string customerName = getValue<Customer>(customer, "name"); However, if you want to find out what the customer's group's name is, it becomes a problem: e.g. string customerGroupName = getValue<Customer>(customer, "Group.name"); Hoping someone can give me some insight on this way out scenario - thanks.

  Read the article

• How to check if TypeIdenitifier(T) is an Object?

  - by John

  I'm creating a generic list class that has a member of type Array(Array of ). The problem is the class descruction,because the class is supposed to be used for types from byte to types inheriting TObject. Specifically: destructor Destroy; var elem:T; begin /*if(T is Tobject) then //Check if T inherits TObject {Compiler error!} for elem in FData do TObject(elem).Free;*/ // do not know how to do it SetLength(FItems,0); //FItems : Array of T inherited Destroy; end; How do I check if T is TObject so I can free every member if the typeidenitifier is a class,for example?

  Read the article

• Catch a generic exception in Java?

  - by Alex Baranosky

  We use JUnit 3 at work and there is no ExpectedException annotation. I wanted to add a utility to our code to wrap this: try { someCode(); fail("some error message"); } catch (SomeSpecificExceptionType ex) { } So I tried this: public static class ExpectedExceptionUtility { public static <T extends Exception> void checkForExpectedException(String message, ExpectedExceptionBlock<T> block) { try { block.exceptionThrowingCode(); fail(message); } catch (T ex) { } } } However, Java cannot use generic exception types in a catch block, I think. How can I do something like this, working around the Java limitation? Is there a way to check that the ex variable is of type T?

  Read the article

• Java generics: actual class as a generic parameter.

  - by user554916

  What do I write instead of "TheClass" to make this work? Or is there an alternative way to do it (possibly without making WithName and WithAge generic)? class Item { NeigborList<TheClass> neighbors; } class WithName extends Item { // here I want neighbors to be a NeighborList<WithName> String name; void someMethod() { System.out.println(neighbors.nearestTo(this).name); } } class WithAge extends Item { // here I want neighbors to be a NeighborList<WithAge> int age; void someOtherMethod() { System.out.println(neighbors.nearestTo(this).age); } }

  Read the article

• Determining whether a class implements a generic list in a T4 template

  - by James Hollingworth

  I'm writing a T4 template which loads some classes from an assembly, does some analysis of the classes and then generates some code. One particular bit of analysis I need to do is to determine whether the class implements a generic list. I can do this pretty simply in C#, e.g. public class Foo : List<string> { } var t = typeof(Foo); if (t.BaseType != null && t.BaseType.IsGenericType && t.BaseType.GetGenericTypeDefinition() == typeof(List<>))) Console.WriteLine("Win"); However T4 templates use the FXCop introspection engine and so you do not have access to the .net reflection API. I've spent the past couple of hours in Reflector but still can't figure it out. Does anyone have any clues about how to do this?

  Read the article

• Common type for generic classes of different types

  - by DinGODzilla

  I have (for example) Dictionary of different generic types (d1, d2, d3, d4) and I want to store them in something var d1 = new Dictionary<int, string>(); var d2 = new Dictionary<int, long>(); var d3 = new Dictionary<DateTime, bool>(); var d4 = new Dictionary<string, object>(); var something = ??? //new List<object> {d1, d2, d3, d4}; Is there any other way how to store that in something with common denominator different than object? Thanks :-)

  Read the article

• Generic class implementing interface fails

  - by Pitming

  A meet a strange problem at compimation saying that a class does not implement an interface. Lets say a v got a class: public Class MyClass { ... } And an interace: public Interface IMyInterface { MyClass PropertyOfMyClass {get;} } and now a generic class: public class MyGeneric<T> where T:MyClass { T PropertyOfMyClass { get{return ...;} } } Until here everythings fine and compiles right. But this will break at compilation time: public class MyGeneric<T>:IMyInterace where T:MyClass { T PropertyOfMyClass { get{return ...;} } } Saying that MyGeneric does not implements method of IMyInterface. But obviously it does, not ?

  Read the article

• Django GenericRelation doesn't save related object's id - is this a bug or am I doing it wrong?

  - by pinkeen

  I have a model with a generic relation (call it A), when creating an instance of this object I pass an instance of another model (call it B) as the initializer of the content_object field (via kwargs of the constructor). If I don't save B before creating A then when saving A the content_object_id is saved to the db as NULL. If I save B before passing it to the constructor of A then everything's allright. It's not logical. I assumed that the ID of the related object (B) is fetched when doing A.save() and it should throw some kind of an exception if B isn't saved yet but it just fails silently. I don't like the current solution (saving B beforhand) because we don't know yet if I will be always willing to keep the object, not just scrap it, and there are performance considerations - what if I will add some another data and save it once more shortly after. class BaseNodeData(models.Model): ... extnodedata_content_type = models.ForeignKey(ContentType, null=True) extnodedata_object_id = models.PositiveIntegerField(null=True) extnodedata = generic.GenericForeignKey(ct_field='extnodedata_content_type', fk_field='extnodedata_object_id') class MarkupNodeData(models.Model): raw_content = models.TextField() Suppose we do: markup = MarkupNodeData(raw_content='...') base = BaseNodeData(..., extnodedata=markup) markup.save() base.save() # both records are inserted to the DB but base is stored with extnodedata_object_id=NULL markup = MarkupNodeData(raw_content='...') base = BaseNodeData(..., extnodedata=markup) base.save() markup.save() # no exception is thrown and everything is the same as above markup = MarkupNodeData(raw_content='...') markup.save() base = BaseNodeData(..., extnodedata=markup) base.save() # this works as expected Of course I can do it this way, but it doesn't change anything: base = BaseNodeData(...) base.extnodedata = markup My question is - is this a bug in django which I should report or maybe I'm doing something wrong. Docs on GenericRelations aren't exactly verbose.

  Read the article

< Previous Page | 84 85 86 87 88 89 90 91 92 93 94 95  | Next Page >