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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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  • 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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  • Create Java method from a string?

    - by drozzy
    Is it possible in Java, to declare a method with a string instead of an identifier? For example can I do something like the following: class Car{ new Method("getFoo", { return 1+1; }); } //Use it Car car = new Car(); car.getFoo(); EDIT: I am adding a Purpose WHY I need this. In order to not hardcode method names when using Jersey and it's UriBuilder, which requires a method name: https://jsr311.dev.java.net/nonav/releases/1.1/javax/ws/rs/core/UriBuilder.html See path() method with signature: public abstract UriBuilder path(java.lang.Class resource, java.lang.String method) throws java.lang.IllegalArgumentException I hope my question is clear, if not - let me know and I can clarify it.

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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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  • 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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  • Make a usable Join relationship with LINQ on top of a database CSV design error

    - by jdk
    I'm looking for a way to fix and/or abstract away a comma-separated values (CSV) list in a database field in order to reconstruct a usable relationship such that I can properly join the two tables below and query them using LINQ and its Join method. Following is a sample showing the Person table and CsvArticleIds field having a CSV value to represent a one-to-many association with Article records. TABLE [dbo].[Person] Id Name CsvArticleIds -- ---------- -------- 1 Joe "15,22" 5 Ed "22" 10 Arnie "8,15,22" ^^^(Of course a link table should have been created; nonetheless the relationship with articles is trapped inside that list of CSV values.) TABLE [dbo].[Article] Id Title -- ---------- 8 Beginning C# 15 A Historic look at Programming in the 90s 22 Gardening in January Additional Info the fix can be at any level: C#.NET or SQL Server something easy because I will be repeating the solution for many other CSV values in other tables. Elegant is nice too. not looking for efficiency because this is part of a one-time data migration task and can take as long as it wants to run.

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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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  • C++ overloading virtual = operator

    - by taz
    Hello, here is the code for my question: class ICommon { public: virtual ICommon& operator=(const ICommon & p)const=0; }; class CSpecial : public ICommon { public: CSpecial& operator=(const CSpecial & cs) { //custom operations return *this; } }; CSpecial obj; Basically: I want the interface ICommon to force it's descendants to implement = operator but don't want to have any typecasts in the implementation. The compiler says "can't instantiate an abstract class. Any help/advice will be appreciated.

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  • Choosing a design pattern for a class that might change it's internal attributes

    - by the_drow
    I have a class that holds arbitrary state and it's defined like this: class AbstractFoo { }; template <class StatePolicy> class Foo : public StatePolicy, public AbstractFoo { }; The state policy contains only protected attributes that represent the state. The state might be the same for multiple behaviors and they can be replaced at runtime. All Foo objects have the same interface to abstract the state itself and to enable storing Foo objects in containers. I would like to find the least verbose and the most maintainable way to express this.

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  • creative way for implementing Data object with its corresponding business logic class in java

    - by ekeren
    I have a class that need to be serialized (for both persistentcy and client-server communication) for simplicity's sake let's 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 lose my hierarchy freedom, do any of you have any creative solutions for this problem... I also reviewed DAO pattern: http://java.sun.com/blueprints/patterns/DAO.html

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  • Connect two daemons in python

    - by Simon
    What is the best way to connect two daemons in Python? I have daemon A and B. I'd like to receive data generated by B in A's module (maybe bidirectional). Both daemons support plugins, so I'd like to shut communication in plugins. What's the best and cross-platform way to do that? I know few mechanisms from low-level solutions - shared memory (C/C++), linux pipe, sockets (TCP/UDP), etc. and few high-level - queue (JMS, Rabbit), RPC. Both daemons should run on the same host, but obviously better approach is to abstract from connection type. What are typical solutions/libraries in python? I'm looking for an elegant and lightweight solution. I don't need external server, just two processes talking with each other. What should I use in python to do that?

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  • How to send news letters in zend

    - by Sherif
    i am trying to send something like news letter Via Zend_Mail but after 12 mail i got this message Fatal error: Maximum execution time of 30 seconds exceeded in C:\Program Files\Zend\Apache2\htdocs\forga\library\Zend\Mail\Protocol\Abstract.php on line 321 my Code is like: $smtpHost = 'smtp.gmail.com'; $smtpConf = array( 'auth' = 'login', 'ssl' = 'tls', 'port' = '587', 'username' ='[email protected]', 'password' = 'xxxxxxxx' ); $transport = new Zend_Mail_Transport_Smtp($smtpHost, $smtpConf); foreach($users as $user) { $mail = new Zend_Mail(); $mail-setFrom("[email protected]", 'Forga'); $mail-setSubject($subject); if($html=='on') $mail-setBodyHtml($message); else $mail-setBodyText($message); $mail-addto($user); $transport-send($mail); }

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  • what is wrong: "value Parsers is not a member of package scala.util.parsing.combinator"?

    - by Nick Fortescue
    I've got the above odd error message that I don't understand "value Parsers is not a member of package scala.util.parsing.combinator". I'm trying to learn Parser combinators by writing a C parser step by step. I started at token, so I have the classes: import util.parsing.combinator.JavaTokenParsers object CeeParser extends JavaTokenParsers { def token: Parser[CeeExpr] = ident } abstract class CeeExpr case class Token(name: String) extends CeeExpr This is as simple as I could make it. The code below works fine, but if I uncomment the commented line I get the error message given above: object Play { def main(args: Array[String]) { //val parser: _root_.scala.util.parsing.combinator.Parsers.Parser[CeeExpr] CeeParser.token val x = CeeParser.token print(x) } } In case it is a problem with my setup, I'm using scala 2.7.6 via the scala-plugin for intellij. Can anyone shed any light on this? The message is wrong, Parsers is a member of scala.util.parsing.combinator.

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  • How do I make this ASP.NET MVC controller more testable?

    - by Ragesh
    I have a controller that overrides OnActionExecuting and does something like this: protected override void OnActionExecuting(ActionExecutingContext filterContext) { base.OnActionExecuting(filterContext); string tenantDomain = filterContext.RouteData.Values["tenantDomain"] as string; if (!string.IsNullOrWhiteSpace(tenantDomain)) { using (var tx = BeginTransaction()) { this.Tenant = repo.FindOne(t => t.Domain == tenantDomain); } } } Tenant is a protected property with a private setter. The class itself is an abstract base controller that my real controllers derive from. I have code in other controllers that looks a lot like this: if (Tenant == null) { // Do something } else { // Do something else } How do I test this code? What I need to do is to somehow set the Tenant property, but I can't because: It's a protected property, and It has a private setter Changing the visibility of Tenant doesn't "feel" right. What are my alternatives to unit test my derived controllers?

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  • Can't instantiate javax.servlet.ServletException

    - by Denis
    Hello, experts! I am trying to create instance of class javax.servlet.ServletException with following code public class MyTroubleViewer { public static void main(String[] args) { javax.servlet.ServletException servletException = new javax.servlet.ServletException("Hello"); System.out.println(servletException.getMessage()); } } But I get exception on creating: Exception in thread "main" java.lang.ClassFormatError: Absent Code attribute in method that is not native or abstract in class file javax/servlet/ServletException ... Maven helps me with dependecies: <dependency> <groupId>javax</groupId> <artifactId>javaee-api</artifactId> <version>6.0</version> <type>jar</type> <scope>compile</scope> </dependency> What am I doing wrong?

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  • Manipulating individual rows of a datagrid

    - by pfranchise
    Hey, recently I started working on a webpage that has a datagrid. I understand how to add datasources and that sort of thing, or at least I am starting to get it. But my question is about manipulating individual rows or cells. Is that only possible during the databind event handler, that is the only place I have been able to do it so far. I am sure there is a more abstract way of doing the things I want to do, but there are times where I just want to say Datagrid.add(row). I mean, if the datagrid is made up of a certain object type, can I make a new object of that type and just chuck it on the end? I am still new to this stuff, so perhaps what I want to do would defeat the purpose of this added abstraction, but figured I would ask around. Thanks for any advice, tips, or tricks people feel like sharing. Edit: for clarification I am using c#, entity framework, asp.net, and an SQL database.

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  • Magento: Why do controller action predispatch events not fire if the controller is rewritten?

    - by mattalexx
    Why do controller action predispatch events not fire if the controller is rewritten? Here is a snippet of store/app/code/core/Mage/Core/Controller/Varien/Action.php: abstract class Mage_Core_Controller_Varien_Action { // [...] public function preDispatch() { // [...] if ($this->_rewrite()) { return; // [What is the purpose if this?] } // [...] // [This is where my event needs to be firing, but this code never gets // executed because the controller is rewritten] Mage::dispatchEvent( 'controller_action_predispatch_'.$this->getFullActionName(), array('controller_action'=>$this) ); } // [...] } I don't know where to start fixing this problem. Anyone out there ever dealt with this before?

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  • What lessons can you learn from software maintanence?

    - by Vasil Remeniuk
    Hello everyone, In the perfect world, all the software developers would work with the cutting edge technologies, creating systems from the scratch. In the real life, almost all of us have to maintain software from time to time (unlucky ones do it on a regular basis). Personally I first 2 years of my career was fixing bugs in the company that no longer exists (it has been taken up by Oracle). And probably the biggest lesson I've learned that time - despite of the pressure, always try to get as much information about the domain as possible (even if it's irrelevant to fixing a specific bug or adding a feature) - abstract domain knowledge doesn't lose value as fast as knowledge about trendy frameworks or methodologies. What lessons have you learned from maintenance?

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  • Zend_Form and Liskov Substitution Principle

    - by blockhead
    A very common pattern I see (I'm picking on Zend Framework, only because I was dealing with it at the moment of this question), is something like this: class My_Form extends Zend_Form { public function init() { $this->addElement(); } } Zend_Form is not an abstract class, but is perfectly usable on its own. This seems to be "recommended" as place to "encapsulate" your forms into a nice class. Does this violate the Liskov Substitution Principle? Each subclass of Zend_Form will have a wildy different behavior than the base class. Would it be better to use composition for this, or am I totally misunderstanding this principle?

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  • Creating a computer with pencil and paper [closed]

    - by Justian Meyer
    This concept has been brought to my attention before, but many people might know it from this popular comic here, where he uses stones instead of points on a paper. This concept is so abstract to me. A full-functioning computer that can manage algorithms, input, output, etc. without electricity? Surely, it's difficult to visualize because my definition of a computer is not exactly what the word sounds like COMPUTE-ER. Can someone help me bring the concept to light - the understanding, how to make one, etc? It seems like it'd be an interesting read, although I think I wouldn't be able to make it do anything. Many thanks in advance for responses. I've tried searching Google, but all I got were ways to diagram code and chart ideas. -.Justian.

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  • Questions about my program and Polymorphism

    - by Strobe_
    Ok, so basically I'm creating a program which allows the user to select a shape (triangle, square, circle) and then it takes in a int and calculates the boundary length and area. I have no problem doing this and have a program that's working perfectly. (https://gist.github.com/anonymous/c63a03c129560a7b7434 4 classes) But now I have to implement this with polymorphism concepts and I'm honestly struggling as to how to do it. I have a basic idea of what I want to do when it comes to inheritance Main | Shapes / | \ triangle circle square But I don't understand how I'm supposed to override when all the methods within the triangle/square/circle classes are unique, there are no "abstract" methods as such that I could inherit from the "Shapes" class. If somebody could make look quickly at the code I linked and suggest a way to do this it would be much appreciated. Sorry if I was bad at explaining this. Thanks.

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  • Passing arguments to anonymous inner classes

    - by synic
    I'm trying to make an API library for our web services, and I'm wondering if it's possible to do something like this: abstract class UserRequest(val userId: Int) { def success(message: String) def error(error: ApiError) } api.invokeRequest(new UserRequest(121) { override def success(message: String) = { // handle success } override def error(error: ApiError) = { // handle the error } } I'm talking about passing parameters to the anonymous inner class, and also overriding the two methods. I'm extremely new to Scala, and I realize my syntax might be completely wrong. I'm just trying to come up with a good design for this library before I start coding it. I'm willing to take suggestions for this, if I'm doing it the completely wrong way, or if there's a better way. The idea is that the API will take some sort of request object, use it to make a request in a thread via http, and when the response has been made, somehow signal back to the caller if the request was a success or an error. The request/error functions have to be executed on the main thread.

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  • Hiding an internal interface in a "friend" assembly

    - by dmo
    I have two assemblies: A and B. A has InternalsVisibleTo set for B. I would like to make calls from A to get information that can only be known by a type defined in B in a way that keeps things internal. I can do this using an internal interface defined in A and implemented explicitly in B. Assembly A internal interface IHasData { Data GetData(); } class ClassA { DoSomething(IHasData); } Assembly B public abstract class ClassB : IHasData { Data IHasData.GetData() { /** do something internal **/ } } The trouble comes when someone references assembly B and derives from ClassB - they get the error: "The type 'AssemblyA.IHasData' is defined in an assembly that is not referenced" even though that type should be invisible to them. If I look at the public type definition I see what I expect - ClassB with no interfaces implemented. Why do I get this error? All of the implementation is in assembly B. I could use IHasData internally in ClassB and that wouldn't require assembly A to be referenced. Can someone help me understand what is going on?

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  • NHibernate: discriminator without common base class?

    - by joniba
    Is it possible to map two classes to the same property without them sharing a common base class? For example, a situation like this: class Rule { public virtual int SequenceNumber { get; set; } public virtual ICondition Condition { get; set; } } interface ICondition { } class ExpressionCondition : ICondition { public virtual string Expression { get; set; } } class ThresholdCondition : ICondition { public virtual int Threshold { get; set; } } I also cannot add some empty abstract class that both conditions inherit from because the two ICondition implementations exist in different domains that are not allowed to reference each other. (Please no responses telling me that this situation should not occur in the first place - I'm aware of it and it doesn't help me.)

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  • If .net sha1 hash expects a byte array, and php sha1() wants a string, can I match the results?

    - by lynn
    I have a set of bytes I want to apply an sha1 hash to. One hash will be in .net, the other in PHP. Then I'll test to see if they match. In .net, you can create a byte array and use sha.ComputeHash(). byte[] data = new byte[DATA_SIZE]; byte[] result; SHA1 sha = new SHA1CryptoServiceProvider(); // This is one implementation of the abstract class SHA1. result = sha.ComputeHash(data); In PHP, you call sha1($string). I can't do anything about the .net side of the code, but how can I get the same hash out of PHP that .net will generate? Please note: I am ONLY able to work on the PHP side of this. The .net stuff is fixed and can't be modified. Thanks!

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