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  • Command Pattern : How to pass parameters to a command ?

    - by Romain Verdier
    My question is related to the command pattern, where we have the following abstraction (C# code) : public interface ICommand { Execute(); } Let's take a simple concrete command, which aims to delete an entity from our application. A Person instance, for example. I'll have a DeletePersonCommand, which implements ICommand. This command needs the Person to delete as a parameter, in order to delete it when Execute method is called. What is the best way to manage parametrized commands ? How to pass parameters to commands, before executing them ?

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  • C#, weird optimization

    - by Snake
    Hi, I'm trying to read my compiled C# code. this is my code: using(OleDbCommand insertCommand = new OleDbCommand("...", connection)) { // do super stuff } But! We all know that a using gets translated to this: { OleDbCommand insertCommand = new OleDbCommand("...", connection) try { //do super stuff } finally { if(insertCommand != null) ((IDisposable)insertCommand).Dispose(); } } (since OleDbCommand is a reference type). But when I decompile my assembly (compiled with .NET 2.0) I get this in Resharper: try { insertCommand = new OleDbCommand("", connection); Label_0017: try { //do super stuff } finally { Label_0111: if ((insertCommand == null) != null) { goto Label_0122; } insertCommand.Dispose(); Label_0122:; } I'm talking about this line: if ((insertCommand == null) != null). True is not null, it never is, nor is false. So how is my object disposed properly? WTF? Thanks! -Kristof

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  • Is it bad practice to make a setter return "this"?

    - by Ken Liu
    Is it a good or bad idea to make setters in java return "this"? public Employee setName(String name){ this.name = name; return this; } This pattern can be useful because then you can chain setters like this: list.add(new Employee().setName("Jack Sparrow").setId(1).setFoo("bacon!")); instead of this: Employee e = new Employee(); e.setName("Jack Sparrow"); ...and so on... list.add(e); ...but it sort of goes against standard convention. I suppose it might be worthwhile just because it can make that setter do something else useful. I've seen this pattern used some places (e.g. JMock, JPA), but it seems uncommon, and only generally used for very well defined APIs where this pattern is used everywhere. Update: What I've described is obviously valid, but what I am really looking for is some thoughts on whether this is generally acceptable, and if there are any pitfalls or related best practices. I know about the Builder pattern but it is a little more involved then what I am describing - as Josh Bloch describes it there is an associated static Builder class for object creation.

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  • Two different tables or just one with bool column?

    - by Aidas
    We have two tables: OriginalDocument and ProcessedDocument. In the first one we put an original, not processed document. After it's validated and processed (converted to our xml format and parsed), it's put into Document table. Processed document can be valid or invalid. Which makes more sense: have two different tables for valid and invalid documents or just have one with 'Valid' column? Some of the columns (~5-7) are irrelevant for invalid document. Storing both invalid and valid documents would also make Document table filled with 'NULL' columns (if document is invalid, information like document number, receiver can be unknown). What else should we consider and weigh, when making this decision?

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  • C# reference collection for storing reference types

    - by ivo s
    I like to implement a collection (something like List<T>) which would hold all my objects that I have created in the entire life span of my application as if its an array of pointers in C++. The idea is that when my process starts I can use a central factory to create all objects and then periodically validate/invalidate their state. Basically I want to make sure that my process only deals with valid instances and I don't re-fetch information I already fetched from the database. So all my objects will basically be in one place - my collection. A cool thing I can do with this is avoid database calls to get data from the database if I already got it (even if I updated it after retrieval its still up-to-date if of course some other process didn't update it but that a different concern). I don't want to be calling new Customer("James Thomas"); again if I initted James Thomas already sometime in the past. Currently I will end up with multiple copies of the same object across the appdomain - some out of sync other in sync and even though I deal with this using timestamp field on the MSSQL server I'd like to keep only one copy per customer in my appdomain (if possible process would be better). I can't use regular collections like List or ArrayList for example because I cannot pass parameters by their real local reference to the their existing Add() methods where I'm creating them using ref so that's not to good I think. So how can this be implemented/can it be implemented at all ? A 'linked list' type of class with all methods working with ref & out params is what I'm thinking now but it may get ugly pretty quickly. Is there another way to implement such collection like RefList<T>.Add(ref T obj)? So bottom line is: I don't want re-create an object if I've already created it before during the entire application life unless I decide to re-create it explicitly (maybe its out-of-date or something so I have to fetch it again from the db). Is there alternatives maybe ?

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  • Using DTOs and BOs

    - by ryanzec
    One area of question for me about DTOs/BOs is about when to pass/return the DTOs and when to pass/return the BOs. My gut reaction tells me to always map NHibernate to the DTOs, not BOs, and always pass/return the DTOs. Then whenever I needed to perform business logic, I would convert my DTO into a BO. The way I would do this is that my BO would have a have a constructor that takes a parameter that is the type of my interface (that defines the required fields/properties) that both my DTO and BO implement as the only argument. Then I would be able to create my BO by passing it the DTO in the constructor (since both with implement the same interface, they both with have the same properties) and then be able to perform my business logic with that BO. I would then also have a way to convert a BO to a DTO. However, I have also seen where people seem to only work with BOs and only work with DTOs in the background where to the user, it looks like there are no DTOs. What benefits/downfalls are there with this architecture vs always using BO's? Should I always being passing/returning either DTOs or BOs or mix and match (seems like mixing and matching could get confusing)?

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  • Android ignoring my setWidth() and setHeight()

    - by popoffka
    So, why does this code: package org.popoffka.apicross; import android.app.Activity; import android.os.Bundle; import android.widget.Button; public class Game extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Button testButton = new Button(this); testButton.setBackgroundResource(R.drawable.cell); testButton.setWidth(20); testButton.setHeight(20); setContentView(testButton); } } ...produce this thing: http://i42.tinypic.com/2hgdzme.png even though there's a setWidth(20) and setHeight(20) in the code? (R.drawable.cell is actually a 20x20 PNG image containing a white cell with a silver border)

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  • SEO with image link alt text vs standard text-based link

    - by Infiniti Fizz
    Hi, I'm currently developing a website and the main navigation is made up of image links because the font used for them isn't standard. My client's only worry is will this mess up search engine optimization? Can I just add alt text to the images like "link 1" or use the name attribute of the anchor tag? Or would it be better to just have the navigation as anchor tags with the names of the links in them like: <a href="...">link 1</a>? I'm new to SEO so really don't know which to suggest to him, Thanks for your time, InfinitiFizz

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  • How to reference a specific object in an array of objects using jTemplates

    - by Travis
    I am using the excellent jTemplates plugin to generate content. Given a data object like this... var data = { name: 'datatable', table: [ {id: 1, name: 'Anne'}, {id: 2, name: 'Amelie'}, {id: 3, name: 'Polly'}, {id: 4, name: 'Alice'}, {id: 5, name: 'Martha'} ] }; ..I'm wondering if it is possible to directly specify an object in an array of objects using $T. (I'm hoping there is something like $T.table:3 available) Currently the only way I can think of to access a specific object in an array is to do something like this... {#foreach $T.table as record} {#if $T.record$iteration == 3} This is record 3! Name: {$T.record.name} {#/if} {#/for} However that seems clumsy... Any suggestions? Thanks

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  • Back Orders for ERP: data model references ?

    - by Patrick Honorez
    I have built an ERP using Sql Server as a back-end. These are the different types of Client documents (there are also Supplier Docs): Order -- impact: BO Delivery Note (also used for returns, with negative quantity) --impact: BO, Stock Invoice --impact: accounting only Credit Note --impact: accounting, BO I use a complex system of self joins (at detail level) to find out the quantities in each OrderDetail that still have a backorder (BO). It'd like to simplify this using a [group] field that could be used through all detail line related to an original order. There are many difficult things to trace: a Return of a product may be due to a defect and thus increase the BO, or it can be just a return, joined with a Credit Note, and then has no impact on BO. My question is: do you know of any real good reference (book, web) for this matter ?

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  • Pattern/Matcher in Java?

    - by user1007059
    I have a certain text in Java, and I want to use pattern and matcher to extract something from it. This is my program: public String getItemsByType(String text, String start, String end) { String patternHolder; StringBuffer itemLines = new StringBuffer(); patternHolder = start + ".*" + end; Pattern pattern = Pattern.compile(patternHolder); Matcher matcher = pattern.matcher(text); while (matcher.find()) { itemLines.append(text.substring(matcher.start(), matcher.end()) + "\n"); } return itemLines.toString(); } This code works fully WHEN the searched text is on the same line, for instance: String text = "My name is John and I am 18 years Old"; getItemsByType(text, "My", "John"); immediately grabs the text "My name is John" out of the text. However, when my text looks like this: String text = "My name\nis John\nand I'm\n18 years\nold"; getItemsByType(text, "My", "John"); It doesn't grab anything, since "My" and "John" are on different lines. How do I solve this?

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  • Practical rules for premature optimization

    - by DougW
    It seems that the phrase "Premature Optimization" is the buzz-word of the day. For some reason, iphone programmers in particular seem to think of avoiding premature optimization as a pro-active goal, rather than the natural result of simply avoiding distraction. The problem is, the term is beginning to be applied more and more to cases that are completely inappropriate. For example, I've seen a growing number of people say not to worry about the complexity of an algorithm, because that's premature optimization (eg http://stackoverflow.com/questions/2190275/help-sorting-an-nsarray-across-two-properties-with-nssortdescriptor/2191720#2191720). Frankly, I think this is just laziness, and appalling to disciplined computer science. But it has occurred to me that maybe considering the complexity and performance of algorithms is going the way of assembly loop unrolling, and other optimization techniques that are now considered unnecessary. What do you think? Are we at the point now where deciding between an O(n^n) and O(n!) complexity algorithm is irrelevant? What about O(n) vs O(n*n)? What do you consider "premature optimization"? What practical rules do you use to consciously or unconsciously avoid it? This is a bit vague, but I'm curious to hear other peoples' opinions on the topic.

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  • Value objects in DDD - Why immutable?

    - by Hobbes
    I don't get why value objects in DDD should be immutable, nor do I see how this is easily done. (I'm focusing on C# and Entity Framework, if that matters.) For example, let's consider the classic Address value object. If you needed to change "123 Main St" to "123 Main Street", why should I need to construct a whole new object instead of saying myCustomer.Address.AddressLine1 = "123 Main Street"? (Even if Entity Framework supported structs, this would still be a problem, wouldn't it?) I understand (I think) the idea that value objects don't have an identity and are part of a domain object, but can someone explain why immutability is a Good Thing? EDIT: My final question here really should be "Can someone explain why immutability is a Good Thing as applied to Value Objects?" Sorry for the confusion! EDIT: To clairfy, I am not asking about CLR value types (vs reference types). I'm asking about the higher level DDD concept of Value Objects. For example, here is a hack-ish way to implement immutable value types for Entity Framework: http://rogeralsing.com/2009/05/21/entity-framework-4-immutable-value-objects. Basically, he just makes all setters private. Why go through the trouble of doing this?

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  • Refactor/rewrite code or continue?

    - by Dan
    I just completed a complex piece of code. It works to spec, it meets performance requirements etc etc but I feel a bit anxious about it and am considering rewriting and/or refactoring it. Should I do this (spending time that could otherwise be spent on features that users will actually notice)? The reasons I feel anxious about the code are: The class hierarchy is complex and not obvious Some classes don't have a well defined purpose (they do a number of unrelated things) Some classes use others internals (they're declared as friend classes) to bypass the layers of abstraction for performance, but I feel they break encapsulation by doing this Some classes leak implementation details (eg, I changed a map to a hash map earlier and found myself having to modify code in other source files to make the change work) My memory management/pooling system is kinda clunky and less-than transparent They look like excellent reasons to refactor and clean code, aiding future maintenance and extension, but could be quite time consuming. Also, I'll never be perfectly happy with any code I write anyway... So, what does stackoverflow think? Clean code or work on features?

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  • Many-To-Many dimensional model

    - by Mevdiven
    Folks, I have a dimension table called DIM_FILE which holds information of the files we received from customers. Each file has detail records which constitutes my FACT table, CUST_DETAIL. In the main process, file is gone through several stages and each stage tags a status to it. Long in a short, I have many-to-many relationship. Any ideas around star schema dimensional modeling. A customer record only belong to a single file and a file can have multiple statuses. FACT ---- CustID FileID AmountDue DIM_FILE -------- FileID FileName DateReceived FILE_STATUS ----------- FileID StatusDateTime StatusCode

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  • Object Oriented Programming in AS3

    - by Jordan
    I'm building a game in as3 that has balls moving and bouncing off the walls. When the user clicks an explosion appears and any ball that hits that explosion explodes too. Any ball that then hits that explosion explodes and so on. My question is what would be the best class structure for the balls. I have a level system to control levels and such and I've already come up with working ways to code the balls. Here's what I've done. My first attempt was to create a class for Movement, Bounce, Explosion and finally Orb. These all extended each other in the order I just named them. I got it working but having Bounce extend Movement and Explosion extend Bounce, it just doesn't seem very object oriented because what if I wanted to add a box class that didn't move, but did explode? I would need a separate class for that explosion. My second attempt was to create Movement, Bounce and Explosion without extending anything. Instead I passed in a reference to the Orb class to each. Then the class stores that reference and does what it needs to do based on events that are dispatched by the Orb such as update, which was broadcast from Orb every enter frame. This would drive the movement and bounce and also the explosion when the time came. This attempt worked as well but it just doesn't seem right. I've also thought about using Interfaces but because they are more of an outline for classes, I feel like code reuse goes out the window as each class would need its own code for a specific task even if that task is exactly the same. I feel as if I'm searching for some form of multiple inheritance for classes that as3 does not support. Can someone explain to me a better way of doing what I'm attempting to do? Am I being to "Object Oriented" by having classed for Movement, Bounce, Explosion and Orb? Are Interfaces the way to go? Any feedback is appreciated!

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  • Returning large collections from WCF Serivce

    - by Nate Bross
    I'm trying to determine the best approach for building a WCF Service, and the area I'm struggling with most is returning lists of objects. The built-in maxMessageSize of 64k seems pretty high, and I really don't want to bump it up (quick googling finds 100s of places bumping the maxMessageSize up to multi-gigabyte range which seems foolish). But, when I'm returning a collection of objects (~150 items) I am exceeding the default 64k. I'm almost to the point of returning my own class which inherits IEnumerable and has properties for hasNext, hasPrevious and PageSize so that I can implement paging on the client side -- this seems like alot of code. The other option is to jackup the maxMessageSize and hope for the best, but that feels wrong. All other aspects of my service are working great, its just returning large collectiosn where I'm having issues. For background, there are two types of consumers of this service, UI applications which will be primarly web and/or wpf applications, and data processing applications, .NET console apps, and maybe some other non-UI apps. For the UI applications, I would like to keep them responsive and keep the messageSize low, on the console apps it doesn't matter as much as they are just pulling data down to do processing and push it back up to the service.

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  • Twitter Bootstrap Collapsible Navbar Duplicating

    - by sixeightzero
    I am working on a project using Twitter Bootstrap. One thing that I noticed is that my pages have duplicate navbars when they are defined as collapsible and the page is resized smaller. Here is the duplicate NavBar: Here is the normal width NavBar: Code: <!DOCTYPE html> <html lang="en"> <!--[if lt IE 7]> <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]--> <!--[if IE 7]> <html class="no-js lt-ie9 lt-ie8"> <![endif]--> <!--[if IE 8]> <html class="no-js lt-ie9"> <![endif]--> <!--[if gt IE 8]><!--> <html class="no-js"> <!--<![endif]--> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <title></title> <meta name="description" content=""> <meta name="viewport" content="width=device-width"> <link rel="stylesheet" href="/assets/css/bootstrap.css"> <style> body { padding-top: 60px; } </style> <link rel="stylesheet" href="/assets/css/bootstrap-responsive.min.css"> <link rel="stylesheet" href="/assets/css/main.css"> <script>window.jQuery || document.write('<script src="/assets/js/vendor/jquery-1.8.1.min.js"><\/script>')</script> <script src="/assets/js/vendor/modernizr-2.6.1-respond-1.1.0.min.js"></script> </head> <body class="dark"> <!--[if lt IE 9]> <p class="chromeframe">You are using an outdated browser. <a href="http://browsehappy.com/">Upgrade your browser today</a> or <a href="http://www.google.com/chromeframe/?redirect=true">install Google Chrome Frame</a> to better experience this site.</p> <![endif]--> <div class="navbar navbar-inverse navbar-fixed-top"> <div class="navbar-inner"> <div class="container"> <a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse"> <span class="icon-bar"></span> <span class="icon-bar"></span> <span class="icon-bar"></span> </a> <a class="brand" href="#">Project name</a> <div class="nav-collapse collapse"> <ul class="nav"> <li class="active"><a href="#">Home</a></li> <li><a href="#about">About</a></li> <li><a href="#contact">Contact</a></li> <li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <b class="caret"></b></a> <ul class="dropdown-menu"> <li><a href="#">Action</a></li> <li><a href="#">Another action</a></li> <li><a href="#">Something else here</a></li> <li class="divider"></li> <li class="nav-header">Nav header</li> <li><a href="#">Separated link</a></li> <li><a href="#">One more separated link</a></li> </ul> </li> </ul> </div><!--/.nav-collapse --> </div> </div> </div> Has anyone else run into this and have some pointers?

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  • Updating multiple tables with LinqToSql in one unit of work

    - by zsharp
    Table 1: int ID-a(pk) Table 2: int ID-a(pk), int ID-b(pk) Table 3: int ID-b(pk), string C I have the data to insert into Table 1. But I do not have the ID-a, which is autogenerated. I have many string C to insert in Table 3. I am trying to insert row into Table 1, get the ID-a to insert in Table 2 along with the ID-b that is auto-Generated in Table 3 when I submit each string C, all in one submission to db. Right now I am calling dc.SubmitChanges twice in same call. Is it efficient to have to submit changes twice on same DataContext or can this be combined further?

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  • Creating Domain Model

    - by Zai
    Hi, I have created a use case of a small application and now I have to create a Domain Model of that use cases of the application and which functions will be implemented in this application. I have no previous experience in Domain Modeling and UML, please suggest me steps to create the domain model or any suggestions, Do I have to have a very solid understanding of Object oriented concepts for creating domain model? The application is simple and creates online poll/voting system and have functions like Register Account, Confirmation Email of account, Membership, Create Poll, Send Poll etc

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  • Is MVVM killing silverlight development?

    - by DeanMc
    This is a question I have had rattling around in my head for some time. I had a chat with a guy the other night who told me he would not be using the navigational framework because he could not figure out how it works with MVVM. As much as I tried to explain that patterns should be taken with a pinch of salt he would not listen. My point is this, patterns are great when they solve some problem. Sometimes only part of the pattern solves a particular problem while the other parts of it cause different problems. The goal of any developer is to build a solid application using a combination of patterns know how and foresight. I feel MVVM is becoming the one pattern to rule them all. As it is not directly supported by .Net some fancy business is needed to make it work. I feel that people are missing the point of the pattern, which is loosely coupled, testable code and instead jumping through hoops and missing out on great experiences trying to follow MVVM to the letter. MVVM is great but I wish it came with a warning or disclaimer for newbies as my fear is people will shy away from silverlight development for fear of being smacked with the mvvm stick. EDIT: Can I just add as an edit, I use and agree with MVVM as a pattern I know when it is and isn't feasible in my projects. My issue is with the encompassing nature it is taking, as if it HAS to be used as part of development. It is being used as an integral feature and not a pattern, which it is.

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