Search Results

Search found 8379 results on 336 pages for 'article'.

Page 296/336 | < Previous Page | 292 293 294 295 296 297 298 299 300 301 302 303  | Next Page >

  • Best practises for Magento Deployment

    - by Spongeboy
    I am looking setting up a deployment process for a highly customised Magento site, and was wondering how other people do this. I will be setting up dev, UAT and prod environments. All the Magento files will be in source control (SVN). At this stage, I can't see any requirements for changing the DB, so the 3 databases will be manually maintained. Specifically, How do you apply Magento upgrades? (Individually in each env, or on dev then roll out, or just give up on upgrades?) What files/folders do leave alone in each environment (e.g. magento/app/etc/local.xml) Do you restrict developers to editing specific files/folders? Do you restrict theme designers to editing specific files/folders? How do you manage database changes? Theme Designer Files/Folders Designers can restricted to editing the following folders- app/design/frontend/your_interface/your_theme/layout/ app/design/frontend/your_interface/your_theme/template/ app/design/frontend/your_interface/your_theme/locale/ skin/frontend/your_interface/your_theme/ Extension Developer Files/Folders Extension developers can edit the following folders/files- /app/code/local /app/etc/modules/<Namespace>_<Module>.xml Database environment management As the store's base URL is stored in the database, you cannot just copy databases between environments. Options include- Overriding the base url in php. Blog article on setting up dev and staging databases Changing the base url in the database after copying. (Where is this stored?) Doing a MySQLDump or backup, then doing a replace on the URL in the SQL file.

    Read the article

  • asp.net: saving js file with c# commands...

    - by ile
    <head runat="server"> <title><asp:ContentPlaceHolder ID="TitleContent" runat="server" /></title> <link href="../../Content/css/layout.css" rel="stylesheet" type="text/css" /> <script type="text/javascript" src="/Areas/CMS/Content/js/jquery-1.3.2.min.js"></script> <script type="text/javascript" src="/Areas/CMS/Content/js/jquery.jeditable.js"></script> <script type="text/javascript" src="/Areas/CMS/Content/js/jeditable.js"></script> <script type="text/javascript"> $(document).ready(function() { $(".naslov_vijesti").editable('<%=Url.Action("UpdateSettings","Article") %>', { submit: 'ok', submitdata: {field: "Title"}, cancel: 'cancel', cssclass: 'editable', width: '99%', placeholder: 'emtpy', indicator: "<img src='../../Content/img/indicator.gif'/>" }); }); </script> </head> This is head tag of site.master file. I would like to remove this multiline part from head and place it in jeditable.js file, which is now empty. If I do copy/paste, then <% %> part won't be executed. In PHP I would save js file as jeditable.js.php and server would compile code that is in <?php ?> tag. Any ideas how to solve this problem? Thanks in advance, Ile

    Read the article

  • How to make safe frequent DataSource switches for AbstractRoutingDataSource?

    - by serg555
    I implemented Dynamic DataSource Routing for Spring+Hibernate according to this article. I have several databases with same structure and I need to select which db will run each specific query. Everything works fine on localhost, but I am worrying about how this will hold up in real web site environment. They are using some static context holder to determine which datasource to use: public class CustomerContextHolder { private static final ThreadLocal<CustomerType> contextHolder = new ThreadLocal<CustomerType>(); public static void setCustomerType(CustomerType customerType) { Assert.notNull(customerType, "customerType cannot be null"); contextHolder.set(customerType); } public static CustomerType getCustomerType() { return (CustomerType) contextHolder.get(); } public static void clearCustomerType() { contextHolder.remove(); } } It is wrapped inside some ThreadLocal container, but what exactly does that mean? What will happen when two web requests call this piece of code in parallel: CustomerContextHolder.setCustomerType(CustomerType.GOLD); //<another user will switch customer type here to CustomerType.SILVER in another request> List<Item> goldItems = catalog.getItems(); Is every web request wrapped into its own thread in Spring MVC? Will CustomerContextHolder.setCustomerType() changes be visible to other web users? My controllers have synchronizeOnSession=true. How to make sure that nobody else will switch datasource until I run required query for current user? Thanks.

    Read the article

  • C Run-Time library part 2

    - by b-gen-jack-o-neill
    Hi, I was suggested when I have some further questions on my older ones, to create newer Question and reffer to old one. So, this is the original question: What is the C runtime library? OK, from your answers, I now get thet statically linked libraries are Microsoft implementation of C standart functions. Now: If I get it right, the scheme would be as follow: I want to use printf(), so I must include which just tels compiler there us functio printf() with these parameters. Now, when I compile code, becouse printf() is defined in C Standart Library, and becouse Microsoft decided to name it C Run Time library, it gets automatically statically linked from libcmt.lib (if libcmt.lib is set in compiler) at compile time. I ask, becouse on wikipedia, in article about runtime library there is that runtime library is linked in runtime, but .lib files are linked at compile time, am I right? Now, what confuses me. There is .dll version of C standart library. But I thought that to link .dll file, you must actually call winapi program to load that library. So, how can be these functions dynamically linked, if there is no static library to provide code to tell Windows to load desired functions from dll? And really last question on this subject - are C Standart library functions also calls to winapi even they are not .dll files like more advanced WinAPI functions? I mean, in the end to access framebuffer and print something you must tell Windows to do it, since OS cannot let you directly manipulate HW. I think of it like the OS must be written to support all C standart library functions same way across similiar versions, since they are statically linked, and can differently support more complex WinAPI calls becouse new version of OS can have adjustements in the .dll file.

    Read the article

  • save html-formatted text to database

    - by yozhik
    Hi all! I want to save html-formatted text to database, but when I do that it is don't save html-symbols like < / ' and others This is how I read article from database for editing: <p class="Title">??????????? ???????:</p> <textarea name="EN" cols="90" rows="20" value="<?php echo $articleArr['EN']; ?>" ></textarea> And this is how I save it to database: function UpdateArticle($ArticleID, $ParentName, $Title, $RU, $EN, $UKR) { //fetch data from database for dropdown lists //connect to db or die) $db = mysql_connect($GLOBALS["gl_dbName"], $GLOBALS["gl_UserName"], $GLOBALS["gl_Password"] ) or die ("Unable to connect"); //to prevenr ????? symbols in unicode - utf-8 coding mysql_query("SET NAMES 'UTF8'"); mysql_set_charset('utf8'); mysql_query("SET NAMES 'utf8' COLLATE 'utf8_general_ci'"); //select database mysql_select_db($GLOBALS["gl_adminDatabase"], $db); $sql = "UPDATE Articles SET AParentName='".$ParentName."', ATitle='".$Title."', RU='".$RU."', EN='".$EN."', UKR='".$UKR."' WHERE ArticleID='".$ArticleID."';"; //execute SQL-query $result = mysql_query($sql, $db); if (!$result) { die('Invalid query: ' . mysql_error()); } //close database = very inportant mysql_close($db); } Help me please, how can I save such texts properly, Thanx!

    Read the article

  • ant ftp task "Could not date test remote file"

    - by avok00
    Hi guys! I am using Ant ftp task to deploy my project files to a remote app server. Ant is not able to detect the date of the remote file and it re-uploads all files every time. When I start Ant in debug mode it says: [ftp] checking date for mailer.war [ftp] Could not date test remote file: mailer.war assuming out of date. The remote server is MS FTP (Windows Vista version) Ant version is 1.8.2; I use commons-net-2.2 and jakarta-oro-2.0.8 (could not find newer version) My ant task looks like this <!-- Deploy new and changed files --> <target name="deploy" depends="package" description="Deploy new and changed files"> <ftp server="localhost" userid="" password="" action="send" depends="yes" passive="true" systemTypeKey="WINDOWS" serverTimeZoneConfig="Europe/Sofia" defaultDateFormatConfig="MMM dd yyyy" recentDateFormatConfig="MMM dd HH:mm" binary="true" retriesAllowed="3" verbose="true"> <fileset dir="${webapp.artefacts.path}"/> </ftp> </target> I read an article here: Ant:The definitive guide that says I need a version of jakarta oro AFTER 2.0.8 to talk to MS FTP servers, but I was not able to find such version. Jakarta oro site - http://jakarta.apache.org/oro/ says the oro project is retired as of 2010, but their latest distribution is from 2003! Please, can anyone help me with this? Any solution or any alternatives to the Ant ftp task? Thanks!

    Read the article

  • Customizing orchard theme parts

    - by madcapnmckay
    Hi, I am trying to write a custom theme for orchard and am not having much success so far. I have read Bertrand Le Roy's article on part alternates but I can't seem to get it to work. I am displaying a list of recent blog posts on the front page, pretty standard. I wish to change the markup produced by the meta data part i.e the time format. I have written a IShapeTableProvider to create blog specific alternates for the metadata summary part. public class MetaDataShapeProvider : IShapeTableProvider { private readonly IWorkContextAccessor workContextAccessor; public MetaDataShapeProvider(IWorkContextAccessor workContextAccessor) { this.workContextAccessor = workContextAccessor; } public void Discover(ShapeTableBuilder builder) { builder .Describe("Parts_Common_Metadata_Summary") .OnDisplaying(displaying => { ContentItem contentItem = displaying.Shape.ContentItem; if (contentItem != null) displaying.ShapeMetadata.Alternates.Add("Metadata__" + contentItem.ContentType); }); } } This is being caught correctly but the contentItem is null. Should I just create an alternate with a fixed name like "Metadata-BlogPost" and use that, to make this general purpose it should really be a dynamic name so I can use another alternate template elsewhere. Thanks, Ian

    Read the article

  • how do simple SQLAlchemy relationships work?

    - by Carson Myers
    I'm no database expert -- I just know the basics, really. I've picked up SQLAlchemy for a small project, and I'm using the declarative base configuration rather than the "normal" way. This way seems a lot simpler. However, while setting up my database schema, I realized I don't understand some database relationship concepts. If I had a many-to-one relationship before, for example, articles by authors (where each article could be written by only a single author), I would put an author_id field in my articles column. But SQLAlchemy has this ForeignKey object, and a relationship function with a backref kwarg, and I have no idea what any of it MEANS. I'm scared to find out what a many-to-many relationship with an intermediate table looks like (when I need additional data about each relationship). Can someone demystify this for me? Right now I'm setting up to allow openID auth for my application. So I've got this: from __init__ import Base from sqlalchemy.schema import Column from sqlalchemy.types import Integer, String class Users(Base): __tablename__ = 'users' id = Column(Integer, primary_key=True) username = Column(String, unique=True) email = Column(String) password = Column(String) salt = Column(String) class OpenID(Base): __tablename__ = 'openid' url = Column(String, primary_key=True) user_id = #? I think the ? should be replaced by Column(Integer, ForeignKey('users.id')), but I'm not sure -- and do I need to put openids = relationship("OpenID", backref="users") in the Users class? Why? What does it do? What is a backref?

    Read the article

  • ANSI or OEM Codepage when using MME and DirectMusic?

    - by Carl Seleborg
    Hello, I noticed that when reading MIDI port names from MME, the names are multi-byte strings encoded using the ANSI Codepage, which my app uses by default. When receiving those names from the DirectMusic driver, the names are wide-character strings encoded with the OEM Codepage. See this article by Raymond Chen for a quick refresher on Codepages. On my German system, this means that when using the current codepage, which turns out to be the ANSI one, I get "Audiogerät" from MME, and "Audiogeröt" from DirectMusic, the latter being wrong. This gets fixed when I treat that last name as OEM-encoded instead. So how do I know with which codepage to decode those names? Why does the name coming from DirectMusic get encoded differently? Does it come from the USB driver? The COM framework? DirectMusic? How can I know for sure which codepage to use when reading the names of my MIDI ports? For info: I use the MultiByteToWideChar() and WideCharToMultiByte() functions to perform the conversions, with CP_ACP and CP_OEMCP as argument for the codepage to use. I use midiInGetDeviceCaps() to get MIDI port information from the MME subsystem... ... and convert MIDIINCAPS.szPname using the CP_ACP (ANSI) codepage. I use IID_IDirectMusic8::EnumPort() to get port information from DirectMusic... ... and convert DMUS_PORTCAPS.wszDescription using the CP_OEMCP codepage.

    Read the article

  • Understanding Symbols In Ruby

    - by Kezzer
    Despite reading this article, I'm still confused as to the representation of the data in memory when it comes to using symbols. If a symbol, two of them contained in different objects, exist in the same memory location, then how is it that they contain different values? I'd have expected the same memory location to contain the same value. As a quote from the link: Unlike strings, symbols of the same name are initialized and exist in memory only once during a session of ruby I just don't understand how it manages to differentiate the values contained in the same memory location. EDIT So let's consider the example: patient1 = { :ruby => "red" } patient2 = { :ruby => "programming" } patient1.each_key {|key| puts key.object_id.to_s} 3918094 patient2.each_key {|key| puts key.object_id.to_s} 3918094 patient1 and patient2 are both hashes, that's fine. :ruby however is a symbol. If we were to output the following: patient1.each_key {|key| puts key.to_s} Then what will be output? "red", or "programming"? FURTHER EDIT I'm still really quite confused. I'm thinking a symbol is a pointer to a value. Let's forget hashes for a second. The questions I have are; can you assign a value to a symbol? Is a symbol just a pointer to a variable with a value in it? If symbols are global, does that mean a symbol always points to one thing?

    Read the article

  • Partially constructed object / Multi threading

    - by reto
    Heya! I'm using joda due to it's good reputation regarding multi threading. It goes great distances to make multi threaded date handling efficient, for example by making all Date/Time/DateTime objects immutable. But here's a situation where I'm not sure if Joda is really doing the right thing. It probably is correct, but I'd be very interested to see the explanation for it. When a toString() of a DateTime is being called Joda does the following: /* org.joda.time.base.AbstractInstant */ public String toString() { return ISODateTimeFormat.dateTime().print(this); } All formatters are thread safe, as they are as well ready-only. But what's about the formatter-factory: private static DateTimeFormatter dt; /* org.joda.time.format.ISODateTimeFormat */ public static DateTimeFormatter dateTime() { if (dt == null) { dt = new DateTimeFormatterBuilder() .append(date()) .append(tTime()) .toFormatter(); } return dt; } This is a common pattern in single threaded applications. I see the following dangers: Race condition during null check -- worst case: two objects get created. No Problem, as this is solely a helper object (unlike a normal singleton pattern situation), one gets saved in dt, the other is lost and will be garbage collected sooner or later. the static variable might point to a partially constructed object before the objec has been finished initialization (before calling me crazy, read about a similar situation in this Wikipedia article. So how does Joda ensure that not partially created formatter gets published in this static variable? Thanks for your explanations! Reto

    Read the article

  • Saving js file with c# commands...

    - by ile
    <head runat="server"> <title><asp:ContentPlaceHolder ID="TitleContent" runat="server" /></title> <link href="../../Content/css/layout.css" rel="stylesheet" type="text/css" /> <script type="text/javascript" src="/Areas/CMS/Content/js/jquery-1.3.2.min.js"></script> <script type="text/javascript" src="/Areas/CMS/Content/js/jquery.jeditable.js"></script> <script type="text/javascript" src="/Areas/CMS/Content/js/jeditable.js"></script> <script type="text/javascript"> $(document).ready(function() { $(".naslov_vijesti").editable('<%=Url.Action("UpdateSettings","Article") %>', { submit: 'ok', submitdata: {field: "Title"}, cancel: 'cancel', cssclass: 'editable', width: '99%', placeholder: 'emtpy', indicator: "<img src='../../Content/img/indicator.gif'/>" }); }); </script> </head> This is head tag of site.master file. I would like to remove this multiline part from head and place it in jeditable.js file, which is now empty. If I do copy/paste, then <% %> part won't be executed. In PHP I would save js file as jeditable.js.php and server would compile code that is in <?php ?> tag. Any ideas how to solve this problem? Thanks in advance, Ile

    Read the article

  • Extension methods for encapsulation and reusability

    - by tzaman
    In C++ programming, it's generally considered good practice to "prefer non-member non-friend functions" instead of instance methods. This has been recommended by Scott Meyers in this classic Dr. Dobbs article, and repeated by Herb Sutter and Andrei Alexandrescu in C++ Coding Standards (item 44); the general argument being that if a function can do its job solely by relying on the public interface exposed by the class, it actually increases encapsulation to have it be external. While this confuses the "packaging" of the class to some extent, the benefits are generally considered worth it. Now, ever since I've started programming in C#, I've had a feeling that here is the ultimate expression of the concept that they're trying to achieve with "non-member, non-friend functions that are part of a class interface". C# adds two crucial components to the mix - the first being interfaces, and the second extension methods: Interfaces allow a class to formally specify their public contract, the methods and properties that they're exposing to the world. Any other class can choose to implement the same interface and fulfill that same contract. Extension methods can be defined on an interface, providing any functionality that can be implemented via the interface to all implementers automatically. And best of all, because of the "instance syntax" sugar and IDE support, they can be called the same way as any other instance method, eliminating the cognitive overhead! So you get the encapsulation benefits of "non-member, non-friend" functions with the convenience of members. Seems like the best of both worlds to me; the .NET library itself providing a shining example in LINQ. However, everywhere I look I see people warning against extension method overuse; even the MSDN page itself states: In general, we recommend that you implement extension methods sparingly and only when you have to. So what's the verdict? Are extension methods the acme of encapsulation and code reuse, or am I just deluding myself?

    Read the article

  • Inject App Settings using Windsor

    - by Damian Powell
    How can I inject the value of an appSettings entry (from app.config or web.config) into a service using the Windsor container? If I wanted to inject the value of a Windsor property into a service, I would do something like this: <properties> <importantIntegerProperty>666</importantIntegerProperty> </properties> <component id="myComponent" service="MyApp.IService, MyApp" type="MyApp.Service, MyApp" > <parameters> <importantInteger>#{importantIntegerProperty}</importantInteger> </parameters> </component> However, what I'd really like to do is take the value represented by #{importantIntegerProperty} from an app settings variable which might be defined like this: <appSettings> <add key="importantInteger" value="666"/> </appSettings> EDIT: To clarify; I realise that this is not natively possible with Windsor and the David Hayden article that sliderhouserules refers to is actually about his own (David Hayden's) IoC container, not Windsor. I'm surely not the first person to have this problem so what I'd like to know is how have other people solved this issue?

    Read the article

  • Why is my PHP string being converted to 1?

    - by animuson
    Ok, so here's the quick rundown. I have a function to generate the page numbers. This: <?php die($ani->e->tmpl->pages("/archive", 1, 15, 1, true)); ?> will output Single Page like expected. But this: <?php $page_numbers = $ani->e->tmpl->pages("/archive", 1, 15, 1, true); ?> <?= $page_numbers ?> will output a simple 1 to the page. Why is it getting converted to a 1? I would expect it to store the 'Single Page' string to the page_numbers variable and then output it (like an echo) exactly the same. EDIT: Running a var_dump($page_numbers) returns int(1)... Here is the entire function in context: <?php // other functions... function show_list() { global $ani; $page_numbers = $ani->e->tmpl->pages("/archive", 1, 15, 1, true); ob_start(); ?> <!-- content:start --> <?php $archive_result = $ani->e->db->build(array("select" => "*", "from" => "animuson_archive", "orderby" => "0-time", "limit" => 15)); while ($archive = $ani->e->db->fetch($archive_result)) { ?> <h2><a href="/archive/article/<?= $archive['aid'] ?>/<?= $archive['title_nice'] ?>"><?= $archive['title'] ?></a></h2> <!-- breaker --> <?php } ?> <?= var_dump($page_numbers) ?> <!-- content:stop --> <?php $ani->e->tmpl->process("box", ob_get_clean()); } // other functions... ?>

    Read the article

  • Shall this Regex do what I expect from it, that is, matching against "A1:B10,C3,D4:E1000"?

    - by Will Marcouiller
    I'm currently writing a library where I wish to allow the user to be able to specify spreadsheet cell(s) under four possible alternatives: A single cell: "A1"; Multiple contiguous cells: "A1:B10" Multiple separate cells: "A1,B6,I60,AA2" A mix of 2 and 3: "B2:B12,C13:C18,D4,E11000" Then, to validate whether the input respects these formats, I intended to use a regular expression to match against. I have consulted this article on Wikipedia: Regular Expression (Wikipedia) And I also found this related SO question: regex matching alpha character followed by 4 alphanumerics. Based on the information provided within the above-linked articles, I would try with this Regex: Default Readonly Property Cells(ByVal cellsAddresses As String) As ReadOnlyDictionary(Of String, ICell) Get Dim validAddresses As Regex = New Regex("A-Za-z0-9:,A-Za-z0-9") If (Not validAddresses.IsMatch(cellsAddresses)) then _ Throw New FormatException("cellsAddresses") // Proceed with getting the cells from the Interop here... End Get End Property Questions 1. Is my regular expression correct? If not, please help me understand what expression I could use. 2. What exception is more likely to be the more meaningful between a FormatException and an InvalidExpressionException? I hesitate here, since it is related to the format under which the property expect the cells to be input, aside, I'm using an (regular) expression to match against. Thank you kindly for your help and support! =)

    Read the article

  • Hierarchical/Nested Database Structure for Comments

    - by Stephen Melrose
    Hi, I'm trying to figure out the best approach for a database schema for comments. The problem I'm having is that the comments system will need to allow nested/hierarchical comments, and I'm not sure how to design this out properly. My requirements are, Comments can be made on comments, so I need to store the tree hierarchy I need to be able to query the comments in the tree hierarchy order, but efficiently, preferably in a fast single query, but I don't know if this is possible I'd need to make some wierd queries, e.g. pull out the latest 5 root comments, and a maximum of 3 children for each one of those I read an article on the MySQL website on this very subject, http://dev.mysql.com/tech-resources/articles/hierarchical-data.html The "Nested Set Model" in theory sounds like it will do what I need, except I'm worried about querying the thing, and also inserting. If this is the right approach, How would I do my 3rd requirement above? If I have 2000 comments, and I add a new sub-comment on the first comment, that will be a LOT of updating to do. This doesn't seem right to me? Or is there a better approach for the type of data I'm wanting to store and query? Thank you

    Read the article

  • gcc, strict-aliasing, and horror stories

    - by Joseph Quinsey
    In http://stackoverflow.com/questions/2906365/gcc-strict-aliasing-and-casting-through-a-union I asked whether anyone had encountered problems with union punning through pointers. So far, the answer seems to be No. This question is broader: do you have any horror stories about gcc and strict-aliasing? Background: Quoting from AndreyT's answer in http://stackoverflow.com/questions/2771023/c99-strict-aliasing-rules-in-c-gcc/2771041#2771041: "Strict aliasing rules are rooted in parts of the standard that were present in C and C++ since the beginning of [standardized] times. The clause that prohibits accessing object of one type through a lvalue of another type is present in C89/90 (6.3) as well as in C++98 (3.10/15). ... It is just that not all compilers wanted (or dared) to enforce it or rely on it." Well, gcc is now daring to do so, with its -fstrict-aliasing switch. And this has caused some problems. See, for example, the excellent article http://davmac.wordpress.com/2009/10/ about a Mysql bug, and the equally excellent discussion in http://cellperformance.beyond3d.com/articles/2006/06/understanding-strict-aliasing.html. Some other less-relevant links: http://stackoverflow.com/questions/1225741/performance-impact-of-fno-strict-aliasing http://stackoverflow.com/questions/754929/strict-aliasing http://stackoverflow.com/questions/262379/when-is-char-safe-for-strict-pointer-aliasing http://stackoverflow.com/questions/725138/how-to-detect-strict-aliasing-at-compile-time So to repeat, do you have a horror story of your own? Problems not indicated by -Wstrict-aliasing would, of course, be preferred. And other C compilers are also welcome.

    Read the article

  • Action Mailer: How do I render dynamic data in an email body that is stored in the database?

    - by Brandon Toone
    I have Action Mailer setup to render an email using the body attribute of my Email model (in the database). I want to be able to use erb in the body but I can't figure out how to get it to render in the sent email message. I'm able to get the body as a string with this code # models/user_mailer.rb def custom_email(user, email_id) email = Email.find(email_id) recipients user.email from "Mail It Example <[email protected]>" subject "Hello From Mail It" sent_on Time.now # pulls the email body and passes a string to the template views/user_mailer/customer_email.text.html.erb body :msg => email.body end I came across this article http://rails-nutshell.labs.oreilly.com/ch05.html which says I can use render but I'm only able to get render :text to work and not render :inline # models/user_mailer.rb def custom_email(user, email_id) email = Email.find(email_id) recipients user.email from "Mail It Example <[email protected]>" subject "Hello From Mail It" sent_on Time.now # body :msg => email.body body :msg => (render :text => "Thanks for your order") # renders text and passes as a variable to the template # body :msg => (render :inline => "We shipped <%= Time.now %>") # throws a NoMethodError end

    Read the article

  • Question about decorator pattern and the abstract decorator class?

    - by es11
    This question was asked already here, but rather than answering the specific question, descriptions of how the decorator pattern works were given instead. I'd like to ask it again because the answer is not immediately evident to me just by reading how the decorator pattern works (I've read the wikipedia article and the section in the book Head First Design Patterns). Basically, I want to know why an abstract decorator class must be created which implements (or extends) some interface (or abstract class). Why can't all the new "decorated classes" simply implement (or extend) the base abstract object themselves (instead of extending the abstract decorator class)? To make this more concrete I'll use the example from the design patterns book dealing with coffee beverages: There is an abstract component class called Beverage Simple beverage types such as HouseBlend simply extend Beverage To decorate beverage, an abstract CondimentDecorator class is created which extends Beverage and has an instance of Beverage Say we want to add a "milk" condiment, a class Milk is created which extends CondimentDecorator I'd like to understand why we needed the CondimentDecorator class and why the class Milk couldn't have simply extended the Beverage class itself and been passed an instance of Beverage in its constructor. Hopefully this is clear...if not I'd simply like to know why is the abstract decorator class necessary for this pattern? Thanks. Edit: I tried to implement this, omitting the abstract decorator class, and it seems to still work. Is this abstract class present in all descriptions of this pattern simply because it provides a standard interface for all of the new decorated classes?

    Read the article

  • Validation L2S question

    - by user158020
    This may be a bit winded because I am new to wpf. I have created a partial class for an entity in my L2S class that is primarily used for validation. It implements the onchanging and onvalidate methods. I am trying to use the MVVM pattern, and in a window/view I have set the datacontext in the xaml: <Window.DataContext> <vm:StartViewModel /> </Window.DataContext> when a user leaves a required field in the view blank, the onchanging event of the partial class is fired when I close the form, not when I save the data. So, if a user leaves the textbox blank, the old value is retained and the onchaging method is fired, but I have no idea how to alert the user of the resulting error. here is my onchanging code in the partial class: partial void Ondocument_titleChanging(string value) { if (value.Length == 0) throw new Exception("Document title is required."); if (value.Length > 256) throw new Exception("Document title cannot be longer than 256 characters."); } throwing an exception doesn't notify the user of the error. it just allows the form to close and rejects the changes to the textbox. hope this makes sense... edit: this example was taken from Scott Guthries article here: http://aspalliance.com/1427_LINQ_to_SQL_Part_5__Binding_UI_using_the_ASPLinqDataSource_Control.5

    Read the article

  • WM_NOTIFY and superclass chaining issue in Win32

    - by DasMonkeyman
    For reference I'm using the window superclass method outlined in this article. The specific issue occurs if I want to handle WM_NOTIFY messages (i.e. for custom drawing) from the base control in the superclass I either need to reflect them back from the parent window or set my own window as the parent (passed inside CREATESTRUCT for WM_(NC)CREATE to the base class). This method works fine if I have a single superclass. If I superclass my superclass then I run into a problem. Now 3 WindowProcs are operating in the same HWND, and when I reflect WM_NOTIFY messages (or have them sent to myself from the parent trick above) they always go to the outermost (most derived) WindowProc. I have no way to tell if they're messages intended for the inner superclass (base messages are supposed to go to the first superclass) or messages intended for the outer superclass (messages from the inner superclass are intended for the outer superclass). These messages are indistinguishable because they all come from the same HWND with the same control ID. Is there any way to resolve this without creating a new window to encapsulate each level of inheritance? Sorry about the wall of text. It's a difficult concept to explain. Here's a diagram. single superclass: SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------/ superclass of a superclass: SuperB::WindowProc() - SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------+-----------------------/ ^--------WM_NOTIFY(A)-----------/ The WM_NOTIFY messages in the second case all come from the same HWND and control ID, so I cannot distinguish between the messages intended for SuperA (from Base) and messages intended for SuperB (from SuperA). Any ideas?

    Read the article

  • [MySQL/PHP] Avoid using RAND()

    - by Andrew Ellis
    So... I have never had a need to do a random SELECT on a MySQL DB until this project I'm working on. After researching it seems the general populous says that using RAND() is a bad idea. I found an article that explains how to do another type of random select. Basically, if I want to select 5 random elements, I should do the following (I'm using the Kohana framework here)? If not, what is a better solution? Thanks, Andrew <?php final class Offers extends Model { /** * Loads a random set of offers. * * @param integer $limit * @return array */ public function random_offers($limit = 5) { // Find the highest offer_id $sql = ' SELECT MAX(offer_id) AS max_offer_id FROM offers '; $max_offer_id = DB::query(Database::SELECT, $sql) ->execute($this->_db) ->get('max_offer_id'); // Check to make sure we're not trying to load more offers // than there really is... if ($max_offer_id < $limit) { $limit = $max_offer_id; } $used = array(); $ids = ''; for ($i = 0; $i < $limit; ) { $rand = mt_rand(1, $max_offer_id); if (!isset($used[$rand])) { // Flag the ID as used $used[$rand] = TRUE; // Set the ID if ($i > 0) $ids .= ','; $ids .= $rand; ++$i; } } $sql = ' SELECT offer_id, offer_name FROM offers WHERE offer_id IN(:ids) '; $offers = DB::query(Database::SELECT, $sql) ->param(':ids', $ids) ->as_object(); ->execute($this->_db); return $offers; } }

    Read the article

  • Is it possible to prevent out-of-order execution by using single volatile

    - by Yan Cheng CHEOK
    By referring article, it is using a pair of volatile to prevent out-of-order execution. I was wondering, is it possible to prevent it using single volatile? void fun_by_thread_1() { this.isNuclearFactory = true; this.factory = new NuclearFactory(); } void fun_by_thread_2() { Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } // If out-of-order execution happens, _factory might // be NuclearFactory instance. _factory.operate(); } Factory factory = new FoodFactory(); volatile boolean isNuclearFactory = false; The reason I ask, is because I have a single guard flag (similar to isNuclearFactory flag), to guard against multiple variables (similar to many Factory). I do not wish to mark all the Factory as volatile. Or, shall I fall into the following solution? void fun_by_thread_1() { try { writer.lock(); this.isNuclearFactory = true; this.factory = new NuclearFactory(); } finally { writer.unlock(); } } void fun_by_thread_2() { try { reader.lock(); Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } } finally { reader.unlock(); } _factory.operate(); } Factory factory = new FoodFactory(); boolean isNuclearFactory = false; P/S: I know instanceof. Factory is just an example to demonstrate of out-of-order problem.

    Read the article

  • Moving from SVN to HG : branching and backup

    - by rorycl
    My company runs svn right now and we are very familiar with it. However, because we do a lot of concurrent development, merging can become very complicated.. We've been playing with hg and we really like the ability to make fast and effective clones on a per-feature basis. We've got two main issues we'd like to resolve before we move to hg: Branches for erstwhile svn users I'm familiar with the "4 ways to branch in Mercurial" as set out in Steve Losh's article. We think we should "materialise" the branches because I think the dev team will find this the most straightforward way of migrating from svn. Consequently I guess we should follow the "branching with clones" model which means that separate clones for branches are made on the server. While this means that every clone/branch needs to be made on the server and published separately, this isn't too much of an issue for us as we are used to checking out svn branches which come down as separate copies. I'm worried, however, that merging changes and following history may become difficult between branches in this model. Backup If programmers in our team make local clones of a branch, how do they backup the local clone? We're used to seeing svn commit messages like this on a feature branch "Interim commit: db function not yet working". I can't see a way of doing this easily in hg. Advice gratefully received. Rory

    Read the article

< Previous Page | 292 293 294 295 296 297 298 299 300 301 302 303  | Next Page >