Search Results

Search found 8692 results on 348 pages for 'patterns and practices'.

Page 182/348 | < Previous Page | 178 179 180 181 182 183 184 185 186 187 188 189  | Next Page >

  • Setting the type of a field in a superclass from a subclass (Java)

    - by Ibolit
    Hi. I am writing a project on Google App Engine, within it I have a number of abstract classes that I hope I will be able to use in my future projects, and a number of concrete classes inheriting from them. Among other abstract classes I have an abstract servlet that does user management, and I hava an abstract user. The AbstractUser has all the necessary fields and methods for storing it in the datastore and telling whether the user is registered with my service or not. It does not implement any project specific functionality. The abstract servlet that manages users, refers only to the methods declared in the AbstractUser class, which allows it to generate links for logging in, logging out and registering (for unregistered users). In order to implement the project-specific user functionality I need to subclass the Abstract user. The servlets I use in my project are all indirect descendants from that abstract user management servlet, and the user is a protected field in it, so the descendant servlets can use it as their own field. However, whenever i want to access any project specific method of the concrete user, i need to cast it to that type. i.e. (abstract user managing servlet) ... AbstractUser user = getUser(); ... abstract protected AbstractUser getUser(); (project-specific abstract servlet) @Override protected AbstractUser getUser() { return MyUserFactory.getUser(); } any other project specific servlet: int a = ((ConcreteUser) user).getA(); Well, what i'd like to do is to somehow make the type of “user” in the superclass depend on something in the project-specific abstract class. Is it at all possible? And i don't want to move all the user-management stuff into a project-specific layer, for i would like to have it for my future projects already written :) Thank you for your help.

    Read the article

  • Defining implicit and explicit casts for C# interfaces

    - by ehdv
    Is there a way to write interface-based code (i.e. using interfaces rather than classes as the types accepted and passed around) in C# without giving up the use of things like implicit casts? Here's some sample code - there's been a lot removed, but these are the relevant portions. public class Game { public class VariantInfo { public string Language { get; set; } public string Variant { get; set; } } } And in ScrDictionary.cs, we have... public class ScrDictionary: IScrDictionary { public string Language { get; set; } public string Variant { get; set; } public static implicit operator Game.VariantInfo(ScrDictionary s) { return new Game.VariantInfo{Language=sd.Language, Variant=sd.Variant}; } } And the interface... public interface IScrDictionary { string Language { get; set; } string Variant { get; set; } } I want to be able to use IScrDictionary instead of ScrDictionary, but still be able to implicitly convert a ScrDictionary to a Game.VariantInfo. Also, while there may be an easy way to make this work by giving IScrDictionary a property of type Game.VariantInfo my question is more generally: Is there a way to define casts or operator overloading on interfaces? (If not, what is the proper C# way to maintain this functionality without giving up interface-oriented design?)

    Read the article

  • Implement abstract class as a local class? pros and cons

    - by sinec
    Hi, for some reason I'm thinking on implementing interface within a some function(method) as local class. Consider following: class A{ public: virtual void MethodToOverride() = 0; }; A * GetPtrToAImplementation(){ class B : public A { public: B(){} ~B(){} void MethodToOverride() { //do something } }; return static_cast<A *>(new B()); } int _tmain(int argc, _TCHAR* argv[]) { A * aInst = GetPtrToAImplementation(); aInst->MethodToOverride(); delete aInst; return 0; } the reason why I'm doing this are: I'm lazy to implement class (B) in separate files MethodToOverride just delegates call to other class Class B shouldn't be visible to other users no need to worry about deleting aInst since smart pointers are used in real implementation So my question is if I'm doing this right? Thanks in advance!

    Read the article

  • How to change the value of progressbar in C#?

    - by shekhar
    Hi, I want to add an progress bar into my C# based application. I would like to know what is the good way of updating its value at particular events? My problem is, I have single function in UI which does all the processing.This function in turn calls many more functions, creates objects, updates database, etc. (basically performs all the work) and returns values in an output file. I have access to that function only. So in this how to update the progressbar's value at the end of each step? What is the best practice for this kind of situation? What is the good way to keep UI logic and business logic seperate? I want to avoid writting progressbar related code in my library code. Please suggest some solution. Thanks and Regards,

    Read the article

  • What pattern is this? php

    - by user151841
    I have several classes that are basically interfaces to database rows. Since the class assumes that a row already exists ( __construct expects a field value ), there is a public static function that allows creation of the row and returns an instance of the class. Here's an example ( without the actual database inserts ): class selfStarter { public $type; public function __construct( $type ) { $this->type = $type; } public static function create( $type ) { if ( ! empty($type) ) { $starter = & new selfStarter($type); return $starter; } } } $obj1 = selfStarter::create( "apple" ); $obj2 = & new selfStarter( "banana" ); What is this pattern called?

    Read the article

  • What is the definition of a Service object ?

    - by Maskime
    I've been working a lot with PHP. But recently i was sent on a work wich use Java. In PHP i used to do a lot of Singleton object but this pattern has not the same signification in Java that it has in PHP. So i wanted to go for an utility class (a class with static method) but my chief doesn't like this kind of classes and ask me to go for services object. So my guess was that a service object is just a class with a constructor that implement some public methods... Am i right ?

    Read the article

  • Do I need to cast the result of strtol to int?

    - by Kristo
    The following code does not give a warning with g++ 4.1.1 and -Wall. int octalStrToInt(const std::string& s) { return strtol(s.c_str(), 0, 8); } I was expecting a warning because strtol returns a long int but my function is only returning a plain int. Might other compilers emit a warning here? Should I cast the return value to int in this case as a good practice?

    Read the article

  • Best way to make an attribute always an array?

    - by Shadowfirebird
    I'm using my MOO project to teach myself Test Driven Design, and it's taking me interesting places. For example, I wrote a test that said an attribute on a particular object should always return an array, so -- t = Thing.new("test") p t.names #-> ["test"] t.names = nil p t.names #-> [] The code I have for this is okay, but it doesn't seem terribly ruby to me: class Thing def initialize(names) self.names = names end def names=(n) n = [] if n.nil? n = [n] unless n.instance_of?(Array) @names = n end attr_reader :names end Is there a more elegant, Ruby-ish way of doing this? (NB: if anyone wants to tell me why this is a dumb test to write, that would be interesting too...)

    Read the article

  • Flexible array members in C - bad?

    - by Lionel
    I recently read that using flexible array members in C was poor software engineering practice. However, that statement was not backed by any argument. Is this an accepted fact? (Flexible array members are a C feature introduced in C99 whereby one can declare the last element to be an array of unspecified size. For example: ) struct header { size_t len; unsigned char data[]; };

    Read the article

  • Should I create a new extension for an xml file?

    - by macleojw
    I'm working with a data model stored in XML files. I want to create some metadata for the model and store it alongside, but would like to be able to distinguish between the two. The data model is imported into some software from time to time and we don't want it to try to import the meta data files. To get round this, I've been thinking of creating a new extension for the metadata xml files (say .mdml). Is this good practice?

    Read the article

  • Call a non member function on an instance before is constructed.

    - by Tom
    Hi everyone. I'm writing a class, and this doubt came up. Is this undef. behaviour? On the other hand, I'm not sure its recommended, or if its a good practice. Is it one if I ensure no exceptions to be thrown in the init function? //c.h class C{ float vx,vy; friend void init(C& c); public: C(); }; //c.cpp C::C() { init(*this); } void init(C& c) //throws() to ensure no exceptions ? { c.vx = 0; c.vy = 0; } Thanks in advance

    Read the article

  • Where to put SVN repository directory in Linux?

    - by alexloh
    I am setting up a new SVN server on Ubuntu Linux. Where is a good place (best practice) to put the repositories? Should I create a new user? The server will be accessed via http:// so no need to create user accounts etc (as was the case for svn://). Many thanks in advance

    Read the article

  • moving a website built on struts to a CMS

    - by fabiobeta
    Hi. Imagine having developed a classical website with java&struts. Now you customer is learning that redeploying the application to change an image or a text is a significant cost. And it asks to add a function to the site: cms-like handling of the contents (editing, versioning, approved publishing). How would you handle this request? Would you develop it in the webapp? Would you merge the webapp with a CMS? Would tou MOVE the webapp into a cms? Would you run away?

    Read the article

  • Is it bad practice to initialize a variable to a dummy value?

    - by froadie
    This question is a result of the answers to this question that I just asked. It was claimed that this code is "ugly" because it initializes a variable to a value that will never be read: String tempName = null; try{ tempName = buildFileName(); } catch(Exception e){ ... System.exit(1); } FILE_NAME = tempName; Is this indeed bad practice? Should one avoid initializing variables to dummy values that will never actually be used? (EDIT - And what about initializing a String variable to "" before a loop that will concatenate values to the String...? Or is this in a separate category? e.g. String whatever = ""; for(String str : someCollection){ whatever += str; } )

    Read the article

  • benefit of having a factory for object creation?

    - by ajsie
    I'm trying to understand the factory design pattern. I don't understand why it's good to have a middleman between the client and the product (object that the client wants). example with no factory: $mac = new Mac(); example with a factory: $appleStore = new AppleStore(); $mac = $appleStore->getProduct('mac'); How does the factory pattern decouple the client from the product? Could someone give an example of a future code change that will impact on example 1 negative, but positive in example 2 so I understand the importance of decoupling? Thanks.

    Read the article

  • detect a string contained by another discontinuously

    - by SpawnCxy
    Recently I'm working on bad content(such as advertise post) filter of a BBS.And I write a function to detect a string is in another string not continuously.Code as below: $str = 'helloguys'; $substr1 = 'hlu'; $substr2 = 'elf'; function detect($a,$b) //function that detect a in b { $c = ''; for($i=0;$i<=strlen($a);$i++) { for($j=0;$j<=strlen($b);$j++) { if($a[$i] == $b[$j]) { $b=substr($b,$j+1); $c .=$a[$i]; break; } } } if($c == $a) return true; else return false; } var_dump(detect($substr1,$str)); //true var_dump(detect($substr2,$str)); //false Since the filter works before the users do their posts so I think the efficiency here is important.And I wonder if there's any better solution? Thanks!

    Read the article

  • Secrets of delivering .NET size large products?

    - by Joan Venge
    In software companies I have seen it's really hard to work on very large products where everything depends on everything else. For instance Microsoft works on C#, F#, .NET, WPF, Visual Studio where these things are interconnected. I don't know how many people are involved, but if it's in 100s, how do they keep in sync with everything, so they design and implement features without conflicting with other dependencies and future plans of other products? I am wondering that if MS is able to do this, they must have a very good system. Any guidelines or secrets for MS or non-MS very large software product delivering?

    Read the article

  • correct technical term for this pattern

    - by Oliver A.
    sometimes I use a pattern which is very similar to the singleton pattern: There is one default instance which and a static get method to aces it. But you may create other instances and pass it as optional parameter and if you want to and you can even replace the default instance with a instance from a child class. So it is NO SINGLETON at all but it is used like one singleton in most cases. Anyone got an idea who to call something like this ? Maybe half*** singleton? domiton?

    Read the article

  • STLifying C++ classes

    - by shambulator
    I'm trying to write a class which contains several std::vectors as data members, and provides a subset of vector's interface to access them: class Mesh { public: private: std::vector<Vector3> positions; std::vector<Vector3> normals; // Several other members along the same lines }; The main thing you can do with a mesh is add positions, normals and other stuff to it. In order to allow an STL-like way of accessing a Mesh (add from arrays, other containers, etc.), I'm toying with the idea of adding methods like this: public: template<class InIter> void AddNormals(InIter first, InIter last); Problem is, from what I understand of templates, these methods will have to be defined in the header file (seems to make sense; without a concrete iterator type, the compiler doesn't know how to generate object code for the obvious implementation of this method). Is this actually a problem? My gut reaction is not to go around sticking huge chunks of code in header files, but my C++ is a little rusty with not much STL experience outside toy examples, and I'm not sure what "acceptable" C++ coding practice is on this. Is there a better way to expose this functionality while retaining an STL-like generic programming flavour? One way would be something like this: (end list) class RestrictedVector<T> { public: RestrictedVector(std::vector<T> wrapped) : wrapped(wrapped) {} template <class InIter> void Add(InIter first, InIter last) { std::copy(first, last, std::back_insert_iterator(wrapped)); } private: std::vector<T> wrapped; }; and then expose instances of these on Mesh instead, but that's starting to reek a little of overengineering :P Any advice is greatly appreciated!

    Read the article

  • Is it always bad idea to use inline css for used-once property?

    - by user93422
    I have a table, with 10 columns. I want to control the width of each column. Each column is unique, right now I create an external CSS style for each column: div#my-page table#members th.name-col { width: 40px; } I know there is a best practice to avoid inline style. I do approve using external CSS for anything look'n'feel related: fonts, colors, images. But is it really better to use external CSS in this case? It does not incur extra maintenance cost. It is easier to produce. Cons I can think of: If you have separate designers and development team - using inline styles will force designers to modify content-file (aspx in my case). It might use more bandwidth. Anything else I've missed?

    Read the article

  • Any reason to clean up unused imports in Java, other than reducing clutter?

    - by Kip
    Is there any good reason to avoid unused import statements in Java? As I understand it, they are there for the compiler, so lots of unused imports won't have any impacts on the compiled code. Is it just to reduce clutter and to avoid naming conflicts down the line? (I ask because Eclipse gives a warning about unused imports, which is kind of annoying when I'm developing code because I don't want to remove the imports until I'm pretty sure I'm done designing the class.)

    Read the article

  • c# class design - what can I use instead of "static abstract"?

    - by Ryan
    I want to do the following public abstract class MyAbstractClass { public static abstract int MagicId { get; } public static void DoSomeMagic() { // Need to get the MagicId value defined in the concrete implementation } } public class MyConcreteClass : MyAbstractClass { public static override int MagicId { get { return 123; } } } However I can't because you can't have static abstract members. I understand why I can't do this - any recommendations for a design that will achieve much the same result? (For clarity - what I am trying to do is provide a library with an abstract base class but the concrete versions MUST implement a few properties/methods themselves and yes, there are good reasons for keeping it static.)

    Read the article

< Previous Page | 178 179 180 181 182 183 184 185 186 187 188 189  | Next Page >