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  • help me to choose between two designs

    - by alex
    // stupid title, but I could not think anything smarter I have a code (see below, sorry for long code but it's very-very simple): namespace Option1 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public AuxClass1 AuxClass { get { return _auxClass; } set { _auxClass = value; } } public MainClass() { _auxClass = new AuxClass1(); } } } namespace Option2 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public string Field1 { get { return _auxClass.Field1; } set { _auxClass.Field1 = value; } } public void Method1() { _auxClass.Method1(); } public void Method2() { _auxClass.Method2(); } public MainClass() { _auxClass = new AuxClass1(); } } } class Program { static void Main(string[] args) { // Option1 Option1.MainClass mainClass1 = new Option1.MainClass(); mainClass1.AuxClass.Field1 = "string1"; mainClass1.AuxClass.Method1(); mainClass1.AuxClass.Method2(); // Option2 Option2.MainClass mainClass2 = new Option2.MainClass(); mainClass2.Field1 = "string2"; mainClass2.Method1(); mainClass2.Method2(); Console.ReadKey(); } } What option (option1 or option2) do you prefer ? In which cases should I use option1 or option2 ? Is there any special name for option1 or option2 (composition, aggregation) ?

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  • C++ include statement required if defining a map in a headerfile.

    - by Justin
    I was doing a project for computer course on programming concepts. This project was to be completed in C++ using Object Oriented designs we learned throughout the course. Anyhow, I have two files symboltable.h and symboltable.cpp. I want to use a map as the data structure so I define it in the private section of the header file. I #include <map> in the cpp file before I #include "symboltable.h". I get several errors from the compiler (MS VS 2008 Pro) when I go to debug/run the program the first of which is: Error 1 error C2146: syntax error : missing ';' before identifier 'table' c:\users\jsmith\documents\visual studio 2008\projects\project2\project2\symboltable.h 22 Project2 To fix this I had to #include <map> in the header file, which to me seems strange. Here are the relevant code files: // symboltable.h #include <map> class SymbolTable { public: SymbolTable() {} void insert(string variable, double value); double lookUp(string variable); void init(); // Added as part of the spec given in the conference area. private: map<string, double> table; // Our container for variables and their values. }; and // symboltable.cpp #include <map> #include <string> #include <iostream> using namespace std; #include "symboltable.h" void SymbolTable::insert(string variable, double value) { table[variable] = value; // Creates a new map entry, if variable name already exist it overwrites last value. } double SymbolTable::lookUp(string variable) { if(table.find(variable) == table.end()) // Search for the variable, find() returns a position, if thats the end then we didnt find it. throw exception("Error: Uninitialized variable"); else return table[variable]; } void SymbolTable::init() { table.clear(); // Clears the map, removes all elements. }

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  • Arrow in nav menus in CSS/JS (e.g. playframework.org)

    - by manmal
    The navigation menu at the top of the www.playframework.org site features a small arrow pointing upward for the currently selected section (Home, Learn, Download,...). I tried to get behind the implementation they used, but I can't wrap my head around it - the resource does not show up in Chrome's Resources window, and an inspection of the elements did not show any signs of a background image, nor a JS interceptor (although I might have missed that). What in hellhound's name is going on there? :)

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  • Is there anything wrong with having a few private methods exposing IQueryable<T> and all public meth

    - by Nate Bross
    I'm wondering if there is a better way to approach this problem. The objective is to reuse code. Let’s say that I have a Linq-To-SQL datacontext and I've written a "repository style" class that wraps up a lot of the methods I need and exposes IQueryables. (so far, no problem). Now, I'm building a service layer to sit on top of this repository, many of the service methods will be 1<-1 with repository methods, but some will not. I think a code sample will illustrate this better than words. public class ServiceLayer { MyClassDataContext context; IMyRepository rpo; public ServiceLayer(MyClassDataContext ctx) { context = ctx; rpo = new MyRepository(context); } private IQueryable<MyClass> ReadAllMyClass() { // pretend there is some complex business logic here // and maybe some filtering of the current users access to "all" // that I don't want to repeat in all of the public methods that access // MyClass objects. return rpo.ReadAllMyClass(); } public IEnumerable<MyClass> GetAllMyClass() { // call private IQueryable so we can do attional "in-database" processing return this.ReadAllMyClass(); } public IEnumerable<MyClass> GetActiveMyClass() { // call private IQueryable so we can do attional "in-database" processing // in this case a .Where() clause return this.ReadAllMyClass().Where(mc => mc.IsActive.Equals(true)); } #region "Something my class MAY need to do in the future" private IQueryable<MyOtherTable> ReadAllMyOtherTable() { // there could be additional constrains which define // "all" for the current user return context.MyOtherTable; } public IEnumerable<MyOtherTable> GetAllMyOtherTable() { return this.ReadAllMyOtherTable(); } public IEnumerable<MyOtherTable> GetInactiveOtherTable() { return this.ReadAllMyOtherTable.Where(ot => ot.IsActive.Equals(false)); } #endregion } This particular case is not the best illustration, since I could just call the repository directly in the GetActiveMyClass method, but let’s presume that my private IQueryable does some extra processing and business logic that I don't want to replicate in both of my public methods. Is that a bad way to attack an issue like this? I don't see it being so complex that it really warrants building a third class to sit between the repository and the service class, but I'd like to get your thoughts. For the sake of argument, lets presume two additional things. This service is going to be exposed through WCF and that each of these public IEnumerable methods will be calling a .Select(m => m.ToViewModel()) on each returned collection which will convert it to a POCO for serialization. The service will eventually need to expose some context.SomeOtherTable which wont be wrapped into the repository.

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  • SELECT product from subclass: How many queries do I need?

    - by Stefano
    I am building a database similar to the one described here where I have products of different type, each type with its own attributes. I report a short version for convenience product_type ============ product_type_id INT product_type_name VARCHAR product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id ... (common attributes to all product) magazine ======== magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id ... (magazine-specific attributes) web_site ======== web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id ... (web-site specific attributes) This way I do not need to make a huge table with a column for each attribute of different product types (most of which will then be NULL) How do I SELECT a product by product.product_id and see all its attributes? Do I have to make a query first to know what type of product I am dealing with and then, through some logic, make another query to JOIN the right tables? Or is there a way to join everything together? (if, when I retrieve the information about a product_id there are a lot of NULL, it would be fine at this point). Thank you

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  • Why doesn't Java Map extends Collection?

    - by polygenelubricants
    I was surprised by the fact that Map<?,?> is not a Collection<?>. I thought it'd make a LOT of sense if it was declared as such: public interface Map<K,V> extends Collection<Map.Entry<K,V>> After all, a Map<K,V> is a collection of Map.Entry<K,V>, isn't it? So is there a good reason why it's not implemented as such?

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  • Should I Split Tables Relevant to X Module Into Different DB? Mysql

    - by Michael Robinson
    I've inherited a rather large and somewhat messy codebase, and have been tasked with making it faster, less noodly and generally better. Currently we use one big database to hold all data for all aspects of the site. As we need to plan for significant growth in the future, I'm considering splitting tables relevant to specific sections of the site into different databases, so if/when one gets too large for one server I can more easily migrate some user data to different mysql servers while retaining overall integrity. I would still need to use joins on some tables across the new databases. Is this a normal thing to do? Would I incur a performance hit because of this?

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  • user height and weight in sql

    - by Samuel
    We are planning to capture a user's height and weight and am looking for ideas on representing them in sql. I have the following questions in mind weight can be expressed in kilograms and grams and height in meters and centimeters, so should I capture them as a BigDecimal with an appropriate precision and scale or capture them as vanilla strings and do the manipulation in the user interface. Note: I am planning to capture the kilograms and grams separately in the user interface. should the metric of measurement be part of the sql (i.e. the end user might want to view this information in pounds, inches according to his preference) OR Should I just support kilograms / meters in the database and do the conversion while showing this in the user interface

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  • How to choose between UUIDs, autoincrement/sequence keys and sequence tables for database primary keys?

    - by Tim
    I'm looking at the pros and cons of these three primary methods of coming up with primary keys for database rows. So assuming I am using a database that supports more than one of these methods, is there a simple heuristic to determine what the best option would be for me? How do considerations such a distributed/multiple masters, performance requirements, ORM use, security and testing have on the choice? Any unexpected drawbacks that one might run into?

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  • PHP Store User Data without Sessions

    - by Sev
    Is there anyway to store users data such as userid, email, etc to be accessible from all pages of a website after they have logged in, but without using sessions or cookies? For example: class User { var $userid; var $username; var $email; .. methods.. } after they login at login.php $currentUser = new User($_POST['username']) now, how do I access $currentUser from another page, such as index.php if I shouldn't use sessions or cookies at all? so that I could do the following in index.php: if ($currentUser->userid > -1) { echo "you are logged in as: " . $currentUser->username; } else { echo "click here to login"; } i asked a similar question before, here, but the answers didn't fulfill my needs.

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  • What is the role of the Router Object in MVC based frameworks

    - by Saif Bechan
    In most MVC based framework I see a router object. If I look at it splits up the uri and decides what controller should be used, and which action should be fired. Even though this makes a lot of sense, I can not give this a place in the MVC patern. Is splitting up the uri not the job of the controller. And then the controller should just decide which class and function to run.

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  • Android & Web: What is the equivalent style for the web?

    - by Legend
    I am quite impressed by the workflow I follow when developing Android applications: Define a layout in an xml file and then write all the code in a code-behind style. Is there an equivalent style for the web? I mean, with a predefined list of widgets that can be defined using a markup language and then control them using code? I have come across Google's Web Toolkit that does something like this but I'd like to hear what other's think as well.

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  • How to Execute Base Class's Method Before Implementors's Method?

    - by DaveDev
    I have the following page public partial class GenericOfflineCommentary : OfflineFactsheetBase { } where OfflineFactsheetBase is defined as public class OfflineFactsheetBase : System.Web.UI.Page { public OfflineFactsheetBase() { this.Load += new EventHandler(this.Page_Load); this.PreInit += new EventHandler(this.Page_PreInit); } protected void Page_PreInit(object sender, EventArgs e) { if (Request.QueryString["data"] != null) { this.PageData = StringCompressor.DecompressString(Request.QueryString["data"]); this.ExtractPageData(); } } } OfflineFactsheetBase has the following virtual method: public virtual void ExtractPageData() { // get stuff relevant to all pages that impmement OfflineFactsheetBase } which is implemented in all pages that impmement OfflineFactsheetBase as follows: public partial class GenericOfflineCommentary : OfflineFactsheetBase { public override void ExtractPageData() { // get stuff relevant to an OfflineCommentary page. } } Currently, only GenericOfflineCommentary's ExtractPageData() is firing. How can I modify this to first run OfflineFactsheetBase's ExtractPageData() and then GenericOfflineCommentary's? edit: I'm trying to avoid having to call base.ExtractPageData() in every implementor. Is this possible?

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  • Should we avoid to use Object as the input parameter/ output value of a method?

    - by developer.cyrus
    Take Java syntax as an example, though the question itself is language independent. If the following snippet takes an object MyAbstractEmailTemplate as input argument in the method setTemplate, the class MyGateway will then become tightly-coupled with the object MyAbstractEmailTemplate, which lessens the re-usability of the class MyGateway. A compromise is to use dependency-injection to ease the instantiation of MyAbstractEmailTemplate. This might solve the coupling problem to some extent, but the interface is still rigid, hardly providing enough ?exibility to other developers/ applications. So if we only use primitive data type (or even plain XML in web service) as the input/ output of a method, it seems the coupling problem no longer exists. So what do you think? public class MyGateway { protected MyAbstractEmailTemplate template; publoc void setTemplate(MyAbstractEmailTemplate template) { this.template = template; } }

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  • O(log n) algorithm for merging lists and computing rank?

    - by Eternal Learner
    Given two sorted lists, each containing n real numbers, is there a O(log?n) time algorithm to compute the element of rank i (where i coresponds to index in increasing order) in the union of the two lists, assuming the elements of the two lists are distinct? I can think of using a Merge procedure to merge the 2 lists and then find the A[i] element in constant time. But the Merge would take O(n) time. How do we solve it in O(log n) time?

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  • Unable to find the cause of an annoying content gap in my HTML/CSS?

    - by user1472747
    I'm quite new to CSS / HTML, and can't find the cause of this little bugger. I want it gone, so that the banner and the nav bar touch each other. Any help is greatly appreciated!! Here is the code for the site. I took out some of the irrelevant code. <!DOCTYPE html> <html> <!-- *****CSS CODE START*****--> <style type="text/css"> #container { margin: 0 auto; width: 900px; background: #fff; } #header { margin-top: 0px; } #header h1 { margin: 0; } #navigation { float: left; width: 900px; background: #333; } #navigation ul { margin: 0; padding: 0; } #navigation ul li { list-style-type: none; display: inline; } #navigation li a { display: block; float: left; padding: 5px 10px; color: #fff; text-decoration: none; border-right: 1px solid #fff; } #navigation li a:hover { background: #383; } #content-container { float: left; width: 900px; background: #fff url(/wp-content/uploads/layout-two-fixed-background.gif) repeat-y 100% 0; } #content { clear: left; float: left; width: 619px; height: 720px; padding: 10px 0; margin: 0 0 0 0px; display: inline; overflow: auto; } #content h2 { margin: 0; color: #003D5D; padding:10px; } #contentBody { padding:10px; font-size:22px; } #aside { float: right; width: 280px; padding: 20px 0; margin: 0 0px 0 0; display: inline; background: #cccccc; height: 700px; border-left: 1px solid #333 ; } #aside h3 { margin: 0 20px; color: #003D5D; font-family: Times New Roman; } #asideText { margin: 0 20px; font-family: Times New Roman;} #footer { clear: both; background: #ccc; text-align: right; padding: 5px; height: 1%; border-top: 1px solid #333 ; } </style> <!-- *****CSS CODE END***** --> <!-- *****HTML CODE START***** --> <body> <div id="container"> <div id="header"> <img src = file:///Users/jduffy/Desktop/projectSite/banner1.jpg> </img> </div> <div id="navigation"> <ul> <li><a href="file:///Users/jduffy/Desktop/projectSite/home">Home</a></li> <li><a href="file:///Users/jduffy/Desktop/projectSite/theProject">The Project</a></li> <li><a href="file:///Users/jduffy/Desktop/projectSite/Pictures">Pictures</a></li> <li><a href="file:///Users/jduffy/Desktop/projectSite/Contact">Contact us</a></li> </ul> </div> <div id="content-container"> <div id="content"> <h2> Page heading </h2> <div id="contentBody"> <p> home pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome page home pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome page home pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome pagehome page </p> <p> test2 </p> <p> test3 </p> </div> </div> <div id="aside"> <div id="asideHeading"> <h3> Aside Heading </h3> </div> <div id="asideText"> <p> test5 </p> </div> </div> <div id="footer"> <text id="footerDate">0</text> </div> </div> </div> </body> <!-- *****HTML CODE END***** --> </html> <!-- *****JavaScript CODE START***** --> <script type="text/javascript"> /*date*/ var today = new Date(); document.getElementById("footerDate").innerHTML = today; </script> <!-- *****JavaScript CODE END***** -->

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  • Detect session hang and kill it

    - by Jack Juiceson
    Hi all, I have an asp.net page that runs certain algorithm and returns it's output. I was wondering what will happen and how to handle a case where the algorithm due to a bug goes into infinite loop. It will hog the cpu and other sessions will be served very slowly. I would love to have a way to tell IIS, if processing Algo.aspx takes more than 5 seconds, kill it or something like that. Thanks in advance

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  • What are the differences between MVP, Presentation Model, MVVM and MVC?

    - by Nicholas
    I have a pretty good idea how each of these patterns work some of the minor differences between them, but are they really all that different from each other? It seems to me that the Presenter, Presentation Model, ViewModel and Controller are essentially the same concept. Why couldn't I classify all of these concepts as controllers? I feel like it might simplify the entire idea a great deal. Can anyone give a clear description of their differences? I want to clarify that I do understand how the patterns work, and have implemented most of them in one technology or another. What I am really looking for is someone's experience with one of these patterns, and why they would not consider their ViewModel a controller for instance.

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  • Why can't I create an abstract constructor on an abstract C# class?

    - by Anthony D
    I am creating an abstract class. I want each of my derived classes to be forced to implement a specific signature of constructor. As such, I did what I would have done has I wanted to force them to implement a method, I made an abstract one. public abstract class A { abstract A(int a, int b); } However I get a message saying the abstract modifier is invalid on this item. My goal was to force some code like this. public class B : A { public B(int a, int b) : base(a, b) { //Some other awesome code. } } This is all C# .NET code. Can anyone help me out? Update 1 I wanted to add some things. What I ended up with was this. private A() { } protected A(int a, int b) { //Code } That does what some folks are saying, default is private, and the class needs to implement a constructor. However that doesn't FORCE a constructor with the signature A(int a, int b). public abstract class A { protected abstract A(int a, int b) { } } Update 2 I should be clear, to work around this I made my default constructor private, and my other constructor protected. I am not really looking for a way to make my code work. I took care of that. I am looking to understand why C# does not let you do this.

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  • Database schema to store AND, OR relation, association

    - by user455387
    Many thanks for your help on this. In order for an entreprise to get a call for tender it must meet certain requirements. For the first example the enterprise must have a minimal class 4, and have qualification 2 in sector 5. Minimal class is always one number. Qualification can be anything (single, or multiple using AND, OR logical operators) I have created tables in order to map each number to it's given name. Now I need to store requirements in the database. minimal class 4 Sector Qualification 5.2 minimal class 2 Sector Qualifications 3.9 and 3.10 minimal class 3 Sector Qualifications 6.1 or 6.3 minimal class 1 Sector Qualifications (3.1 and 3.2) or 5.6 class Domain < ActiveRecord::Base has_many :domain_classes has_many :domain_sectors has_many :sector_qualifications, :through => :domain_sectors end class DomainClass < ActiveRecord::Base belongs_to :domain end class DomainSector < ActiveRecord::Base belongs_to :domain has_many :sector_qualifications end class SectorQualification < ActiveRecord::Base belongs_to :domain_sector end create_table "domains", :force => true do |t| t.string "name" end create_table "domain_classes", :force => true do |t| t.integer "number" t.integer "domain_id" end create_table "domain_sectors", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_id" end create_table "sector_qualifications", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_sector_id" end

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  • How should I build a simple database package for my python application?

    - by Carson Myers
    I'm building a database library for my application using sqlite3 as the base. I want to structure it like so: db/ __init__.py users.py blah.py etc.py So I would do this in Python: import db db.users.create('username', 'password') I'm suffering analysis paralysis (oh no!) about how to handle the database connection. I don't really want to use classes in these modules, it doesn't really seem appropriate to be able to create a bunch of "users" objects that can all manipulate the same database in the same ways -- so inheriting a connection is a no-go. Should I have one global connection to the database that all the modules use, and then put this in each module: #users.py from db_stuff import connection Or should I create a new connection for each module and keep that alive? Or should I create a new connection for every transaction? How are these database connections supposed to be used? The same goes for cursor objects: Do I create a new cursor for each transaction? Create just one for each database connection?

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