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  • Make is more OOPey - good structure?

    - by Tom
    Hi, I just want advice on whether I could improve structure around a particular class which handles all disk access functions The structure of my program is that I have a class called Disk which gets data from flatfiles and databases on a, you guessed it, hard disk drive. I have functions like LoadTextFileToStringList, WriteStringToTextFile, DeleteLineInTextFile etc which are kind of "generic methods" In the same class I also have some more specific methods such as GetXFromDisk where X might be a particular field in a database table/query. Should I separate out the generic methods from the specialised. Should I make another class which inherits the generic methods. At the moment my class is static as there is no need to have an internal state of the class. I'm not really OOPing am I? Thanks Thomas

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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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  • How to store a list in a column of a database table.

    - by John Berryman
    Howdy! So, per Mehrdad's answer to a related question, I get it that a "proper" database table column doesn't store a list. Rather, you should create another table that effectively holds the elements of said list and then link to it directly or through a junction table. However, the type of list I want to create will be composed of unique items (unlike the linked question's fruit example). Furthermore, the items in my list are explicitly sorted - which means that if I stored the elements in another table, I'd have to sort them every time I accessed them. Finally, the list is basically atomic in that any time I wish to access the list, I will want to access the entire list rather than just a piece of it - so it seems silly to have to issue a database query to gather together pieces of the list. AKX's solution (linked above) is to serialize the list and store it in a binary column. But this also seems inconvenient because it means that I have to worry about serialization and deserialization. Is there any better solution? If there is no better solution, then why? It seems that this problem should come up from time to time. ... just a little more info to let you know where I'm coming from. As soon as I had just begun understanding SQL and databases in general, I was turned on to LINQ to SQL, and so now I'm a little spoiled because I expect to deal with my programming object model without having to think about how the objects are queried or stored in the database. Thanks All! John

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  • Inheritance: when implementing an interface which define a base class property why cant the class im

    - by Deepak
    Lets create some interfaces public interface ITimeEventHandler { string Open(); } public interface IJobTimeEventHandler: ITimeEventHandler { string DeleteJob(); } public interface IActivityTimeEventHandler: ITimeEventHandler { string DeleteActivity(); } public interface ITimeEvent { ITimeEventHandler Handler; } Another Interface public interface IJobTimeEvent :ITimeEvent { int JobID; } Create a class public class JobTimeEvent : IJobTimeEvent { public int JobID = 0; public IJobTimeEventHandler Handler = null; } My question is .. when implementing an interface which define a base class property why cant the class implementing interface return a derived class type object ?? For ex in class JobTimeEvent, IJobtimeEvent needs a property of type ITimeEventHandler but why IJobTimeEventHandler type is not allowed which derived from ITimeEventHandler

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  • Where should Nhibernate IPostInsertEventListener go in the 3 tier architecture

    - by Quintin Par
    I have a IPostInsertEventListener implementation like public class NHibernateEventListener : IPostInsertEventListener, IPostUpdateEventListener which catches some entity inserts and does an additional insert to another table for ETL. Essentially it requires references to the Nhibernate, Domain entity and Repository<> Now where do I go about adding this class? If I add it to ApplicationServices I’ll end up referencing Nhibernate at that layer. If I add this to the Data layer, I’ll have to reference Domain (circular). How do I go implementing this class with S#arp principles? Any thoughts?

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  • Is there any reason for an object pool to not be treated as a singleton?

    - by Chris Charabaruk
    I don't necessarily mean implemented using the singleton pattern, but rather, only having and using one instance of a pool. I don't like the idea of having just one pool (or one per pooled type). However, I can't really come up with any concrete situations where there's an advantage to multiple pools for mutable types, at least not any where a single pool can function just as well. What advantages are there to having multiple pools over a singleton pool?

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  • do's and don'ts for writing mysql queries

    - by nik
    One thing I always wonder while writing query is that am I writing most optimized query or not? I know certain things like: 1) using SELECT field1, filed2 instead of SELECT * 2) Giving proper indexes to the tables but I am sure there are more things that should be kept in mind for writing queries, since most of the database can only grow more and optimal query will help gr8 in execution time, Can u share some tips and tricks on writing queries?

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  • Patterns to implement this grammar into C# code

    - by MexicanHacker
    Hey guys, I'm creating this little BNF grammar and I wanted to <template>::= <types><editors> <types>::= <type>+ <type>::= <property>+ <property>::= <name><type> <editors>::= <editor>+ <editor>::= <name><type>(<textfield>|<form>|<list>|<pulldown>)+ <textfield>::= <label><property>[<editable>] <form>::= <label><property><editor> <list>::= <label><property><item-editor> <pulldown>::= <label><property><option>+ <option>::= <value> One possible solution we have in mind is to create POCO's that have annotations of the XMLSerialization namespace, like this, for example: [XMLRoot("template")] public class Template{ [XMLElement("types")] public Types types{ } } However I want to explore more solutions, what do you guys think?

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  • Looking for Suggestion on Multi-Consumer Service Development

    - by DaveDev
    How would I model a system that needs to be able to provide content in a format that would be consumable by iphone, Android or web browser (or whatever). All a new consumer would have to do is build a UI with rules on how to handle the data. I'm thinking something RESTful returning JSON or something. I'm really looking for suggestions on the kinds of things I'd need to learn in order to be able to implement a system on this scale. As an ASP.NET MVC developer, would that be the best framework/archetectrue to go with? Thanks

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  • How to pass data to another droid device when the other device isn't expecting it

    - by James Black
    I am working on an application and one feature that would make it really useful is the ability to share some information, but the other device may not be expecting the data to be sent. For example, if I am reading a really good book, and I realize that a friend may like it, I could use an application to send the data to him, so he could order the book from Amazon. But, since he isn't expecting the data, I would hate for the application to be polling a server every so often, as that will be needlessly draining the battery. Ideally it would be great if there was a way to make a phone call to the target device, send a data packet and end the call. If it could be done and prevent the phone from ringing, then it would be very useful to me. I am curious if there is some way to send data between devices without polling.

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  • How build my own Application Setting

    - by adisembiring
    I want to build a ApplicationSetting for my application. The ApplicationSetting can be stored in a properties file or in a database table. The settings are stored in key-value pairs. E.g. ftp.host = blade ftp.username = dummy ftp.pass = pass content.row_pagination = 20 content.title = How to train your dragon. I have designed it as follows: Application settings reader: interface IApplicationSettingReader { read(); } DatabaseApplicationSettingReader { dao appSettingDao; AppSettings read() { List<AppSettingEntity> listEntity = appSettingsDao.findAll(); Map<String, String> map = new HaspMap<String, String>(); foreach (AppSettingEntity entity : listEntity) { map.put(entity.getConfigName(), entity.getConfigValue()); } return new AppSettings(map); } } DatabaseApplicationSettingReader { dao appSettingDao; AppSettings read() { //read from some properties file return new AppSettings(map); } } Application settings class: AppSettings { private static AppSettings instance; private Map map; Public AppSettings(Map map) { this.map = map; } public static AppSettings getInstance() { if (instance == null) { throw new RuntimeException("Object not configure yet"); } return instance; } public static configure(IApplicationSettingReader reader) { instance = reader.read(); } public String getFtpSetting(String param) { return map.get("ftp." + param); } public String getContentSetting(String param) { return map.get("content." + param); } } Test class: AppSettingsTest { IApplicationSettingReader reader; @Before public void setUp() throws Exception { reader = new DatabaseApplicationSettingReader(); } @Test public void getContentSetting_should_get_content_title() { AppSettings.configure(reader); Instance settings = AppSettings.getInstance(); String title = settings.getContentSetting("title"); assertNotNull(title); Sysout(title); } } My questions are: Can you give your opinion about my code, is there something wrong? I configure my application setting once, while the application start, I configure the application setting with appropriate reader (DbReader or PropertiesReader), I make it singleton. The problem is, when some user edit the database or file directly to database or file, I can't get the changed values. Now, I want to implement something like ApplicationSettingChangeListener. So if the data changes, I will refresh my application settings. Do you have any suggestions how this can be implemented?

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  • Data Modeling of Entity with Attributes

    - by StackOverflowNewbie
    I'm storing some very basic information "data sources" coming into my application. These data sources can be in the form of a document (e.g. PDF, etc.), audio (e.g. MP3, etc.) or video (e.g. AVI, etc.). Say, for example, I am only interested in the filename of the data source. Thus, I have the following table: DataSource Id (PK) Filename For each data source, I also need to store some of its attributes. Example for a PDF would be "numbe of pages." Example for audio would be "bit rate." Example for video would be "duration." Each DataSource will have different requirements for the attributes that need to be stored. So, I have modeled "data source attribute" this way: DataSourceAttribute Id (PK) DataSourceId (FK) Name Value Thus, I would have records like these: DataSource->Id = 1 DataSource->Filename = 'mydoc.pdf' DataSource->Id = 2 DataSource->Filename = 'mysong.mp3' DataSource->Id = 3 DataSource->Filename = 'myvideo.avi' DataSourceAttribute->Id = 1 DataSourceAttribute->DataSourceId = 1 DataSourceAttribute->Name = 'TotalPages' DataSourceAttribute->Value = '10' DataSourceAttribute->Id = 2 DataSourceAttribute->DataSourceId = 2 DataSourceAttribute->Name = 'BitRate' DataSourceAttribute->Value '16' DataSourceAttribute->Id = 3 DataSourceAttribute->DataSourceId = 3 DataSourceAttribute->Name = 'Duration' DataSourceAttribute->Value = '1:32' My problem is that this doesn't seem to scale. For example, say I need to query for all the PDF documents along with thier total number of pages: Filename, TotalPages 'mydoc.pdf', '10' 'myotherdoc.pdf', '23' ... The JOINs needed to produce the above result is just too costly. How should I address this problem?

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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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  • If you are forced to use an Anemic domain model, where do you put your business logic and calculated

    - by Jess
    Our current O/RM tool does not really allow for rich domain models, so we are forced to utilize anemic (DTO) entities everywhere. This has worked fine, but I continue to struggle with where to put basic object-based business logic and calculated fields. Current layers: Presentation Service Repository Data/Entity Our repository layer has most of the basic fetch/validate/save logic, although the service layer does a lot of the more complex validation & saving (since save operations also do logging, checking of permissions, etc). The problem is where to put code like this: Decimal CalculateTotal(LineItemEntity li) { return li.Quantity * li.Price; } or Decimal CalculateOrderTotal(OrderEntity order) { Decimal orderTotal = 0; foreach (LineItemEntity li in order.LineItems) { orderTotal += CalculateTotal(li); } return orderTotal; } Any thoughts?

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  • What is the best database structure for this scenario?

    - by Ricketts
    I have a database that is holding real estate MLS (Multiple Listing Service) data. Currently, I have a single table that holds all the listing attributes (price, address, sqft, etc.). There are several different property types (residential, commercial, rental, income, land, etc.) and each property type share a majority of the attributes, but there are a few that are unique to that property type. My question is the shared attributes are in excess of 250 fields and this seems like too many fields to have in a single table. My thought is I could break them out into an EAV (Entity-Attribute-Value) format, but I've read many bad things about that and it would make running queries a real pain as any of the 250 fields could be searched on. If I were to go that route, I'd literally have to pull all the data out of the EAV table, grouped by listing id, merge it on the application side, then run my query against the in memory object collection. This also does not seem very efficient. I am looking for some ideas or recommendations on which way to proceed. Perhaps the 250+ field table is the only way to proceed. Just as a note, I'm using SQL Server 2012, .NET 4.5 w/ Entity Framework 5, C# and data is passed to asp.net web application via WCF service. Thanks in advance.

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  • Disposing underlying object from finalizer in an immutable object

    - by Juan Luis Soldi
    I'm trying to wrap around Awesomium and make it look to the rest of my code as close as possible to NET's WebBrowser since this is for an existing application that already uses the WebBrowser. In this library, there is a class called JSObject which represents a javascript object. You can get one of this, for instance, by calling the ExecuteJavascriptWithResult method of the WebView class. If you'd call it like myWebView.ExecuteJavascriptWithResult("document", string.Empty).ToObject(), then you'd get a JSObject that represents the document. I'm writing an immutable class (it's only field is a readonly JSObject object) called JSObjectWrap that wraps around JSObject which I want to use as base class for other classes that would emulate .NET classes such as HtmlElement and HtmlDocument. Now, these classes don't implement Dispose, but JSObject does. What I first thought was to call the underlying JSObject's Dispose method in my JSObjectWrap's finalizer (instead of having JSObjectWrap implement Dispose) so that the rest of my code can stay the way it is (instead of having to add using's everywhere and make sure every JSObjectWrap is being properly disposed). But I just realized if more than two JSObjectWrap's have the same underlying JSObject and one of them gets finalized this will mess up the other JSObjectWrap. So now I'm thinking maybe I should keep a static Dictionary of JSObjects and keep count of how many of each of them are being referenced by a JSObjectWrap but this sounds messy and I think could cause major performance issues. Since this sounds to me like a common pattern I wonder if anyone else has a better idea.

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  • Resources on wordpress theme-development

    - by Espenhh
    What are the best resources for Wordpress theme-development? I am currently in the phase of starting my own blog, and don't want to use one of the many free themes. I already have a theme for my website, so I want to read about best-practices. Any advice on how to get started would be very welcome :) I have now created my theme (wohoo!), and thought I should summarize the best resources I found. Lets see.. Resources: ThemeTation's three-part guide to create a wordpress-theme from scratch Nettuts.com's guide: How to Create a Wordpress Theme from Scratch (And Part 2) Didn't actually use this, it's a quite new article, but anyway - it's great. It will get a follow-up in the next few days too.. Wordpress.org's own guide on templates Definatly a must-read for everyone new to wordpress-designing.. "The loop" Essential knowledge, also a must-read Directory of all the template tags Used by wordpress to actually output blog-content.. Inspiration: Smashing Magazine's lists: first, one more, yet another one Wordpress.org's theme-directory

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  • Voting UI for showing like/dislike community comments side-by-side

    - by Justin Grant
    We want to add a comments/reviews feature to our website's plugin gallery, so users can vote up/down a particular plugin and leave an optional short comment about what they liked or didn't like about it. I'm looking for inspiration, ideally a good implementation elsewhere on the web which isn't annoying to end users, isn't impossibly complex to develop, and which enables users to see both good and bad comments side-by-side, like this: Like: 57 votes Dislike: 8 votes --------------------------------- -------------------------------- "great plugin, saved me hours..." "hard to install" "works well on MacOS and Ubuntu" "Broken on Windows Vista with UAC enabled" "integrates well with version 3.2" More... More... Anyone know a site which does something like this?

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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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  • Decorator pattern in C++

    - by AlgoMan
    Can someone give me an example of Decorator pattern in C++ ? I have come across the Java version of it. But C++ i have found it difficult to understand the examples that are given.

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  • Fixed footer with 960.gs

    - by Oguz
    I want to create fixed footer but , is it possible with 960 gs , because I am having trouble with height of container div . I can no set it to %100. <div class="container_12" > <div class="grid_3" id="side-space"></div> <div class="grid_6"> <div id="content-box"></div> </div> <div class="grid_3" id="side-space"></div> </div>

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