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  • What is this Design Pattern?

    - by Can't Tell
    I read the Wikipedia articles on FactoryMethod and AbstractFactory but the following code doesn't seem to fit anywhere. Can someone explain to me what the following pattern is or if it is an anti-pattern? interace PaymentGateway{ void makePayment(); } class PaypalPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class AuthorizeNetPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class PaymentGatewayFacotry{ PaymentGateway createPaymentGateway(int gatewayId) { if(gatewayId == 1) return PaypalPaymentGateway(); else if(gatewayId == 2) return AuthorizeNetPaymentGateway(); } } Let's say the user selects the payment method using a radio button on an html page and the gatewayId is derived from the radio button value. I have seen code like this and thought it was the AbstractFactory pattern but after reading the Wikipedia article, I'm having doubts.

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  • Is the Observer pattern adequate for this kind of scenario?

    - by Omega
    I'm creating a simple game development framework with Ruby. There is a node system. A node is a game entity, and it has position. It can have children nodes (and one parent node). Children are always drawn relatively to their parent. Nodes have a @position field. Anyone can modify it. When such position is modified, the node must update its children accordingly to properly draw them relatively to it. @position contains a Point instance (a class with x and y properties, plus some other useful methods). I need to know when a node's @position's state changes, so I can tell the node to update its children. This is easy if the programmer does something like this: @node.position = Point.new(300,300) Because it is equivalent to calling this: # Code in the Node class def position=(newValue) @position = newValue update_my_children # <--- I know that the position changed end But, I'm lost when this happens: @node.position.x = 300 The only one that knows that the position changed is the Point instance stored in the @position property of the node. But I need the node to be notified! It was at this point that I considered the Observer pattern. Basically, Point is now observable. When a node's position property is given a new Point instance (through the assignment operator), it will stop observing the previous Point it had (if any), and start observing the new one. When a Point instance gets a state change, all observers (the node owning it) will be notified, so now my node can update its children when the position changes. A problem is when this happens: @someNode.position = @anotherNode.position This means that two nodes are observing the same point. If I change one of the node's position, the other would change as well. To fix this, when a position is assigned, I plan to create a new Point instance, copy the passed argument's x and y, and store my newly created point instead of storing the passed one. Another problem I fear is this: somePoint = @node.position somePoint.x = 500 This would, technically, modify @node's position. I'm not sure if anyone would be expecting that behavior. I'm under the impression that people see Point as some kind of primitive rather than an actual object. Is this approach even reasonable? Reasons I'm feeling skeptical: I've heard that the Observer pattern should be used with, well, many observers. Technically, in this scenario there is only one observer at a time. When assigning a node's position as another's (@someNode.position = @anotherNode.position), where I create a whole new instance rather than storing the passed point, it feels hackish, or even inefficient.

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  • Ruby on Rails: Using XML Builder Partials

    - by randombits
    Partials in XML builder are proving to be non-trivial. After some initial Google searching, I found the following to work, although it's not 100% xml.foo do xml.id(foo.id) xml.created_at(foo.created_at) xml.last_updated(foo.updated_at) foo.bars.each do |bar| xml << render(:partial => 'bar/_bar', :locals => { :bar => bar }) end end this will do the trick, except the XML output is not properly indented. the output looks something similar to: <foo> <id>1</id> <created_at>sometime</created_at> <last_updated>sometime</last_updated> <bar> ... </bar> <bar> ... </bar> </foo> The <bar> element should align underneath the <last_updated> element, it is a child of <foo> like this: <foo> <id>1</id> <created_at>sometime</created_at> <last_updated>sometime</last_updated> <bar> ... </bar> <bar> ... </bar> </foo> Works great if I copy the content from bar/_bar.xml.builder into the template, but then things just aren't DRY.

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  • OOW content for Pattern Matching....

    - by KLaker
    If you missed my sessions at OpenWorld then don't worry - all the content we used for pattern matching (presentation and hands-on lab) is now available for download. My presentation "SQL: The Best Development Language for Big Data?" is available for download from the OOW Content Catalog, see here: https://oracleus.activeevents.com/2013/connect/sessionDetail.ww?SESSION_ID=9101 For the hands-on lab ("Pattern Matching at the Speed of Thought with Oracle Database 12c") we used the Oracle-By-Example content. The OOW hands-on lab uses Oracle Database 12c Release 1 (12.1) and uses the MATCH_RECOGNIZE clause to perform some basic pattern matching examples in SQL. This lab is broken down into four main steps: Logically partition and order the data that is used in the MATCH_RECOGNIZE clause with its PARTITION BY and ORDER BY clauses. Define patterns of rows to seek using the PATTERN clause of the MATCH_RECOGNIZE clause. These patterns use regular expressions syntax, a powerful and expressive feature, applied to the pattern variables you define. Specify the logical conditions required to map a row to a row pattern variable in the DEFINE clause. Define measures, which are expressions usable in the MEASURES clause of the SQL query. You can download the setup files to build the ticker schema and the student notes from the Oracle Learning Library. The direct link to the example on using pattern matching is here: http://apex.oracle.com/pls/apex/f?p=44785:24:0::NO:24:P24_CONTENT_ID,P24_PREV_PAGE:6781,2.

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  • Observer pattern used with decorator pattern

    - by icelated
    I want to make a program that does an order entry system for beverages. ( i will probably do description, cost) I want to use the Decorator pattern and the observer pattern. I made a UML drawing and saved it as a pic for easy viewing. This site wont let me upload as a word doc so i have to upload a pic - i hope its easily viewable.... I need to know if i am doing the UML / design patterns correctly before moving on to the coding part. Beverage is my abstract component class. Espresso, houseblend, darkroast are my concrete subject classes.. I also have a condiment decorator class milk,mocha,soy,whip. would be my observer? because they would be interested in data changes to cost? Now, would the espresso,houseblend etc, be my SUBJECT and the condiments be my observer? My theory is that Cost is a changes and that the condiments need to know the changes? So, subject = esspresso,houseblend,darkroast,etc.. // they hold cost() Observer = milk,mocha,soy,whip? // they hold cost() would be the concrete components and the milk,mocha,soy,whip? would be the decorator! So, following good software engineering practices "design to an interface and not implementation" or "identify things that change from those that dont" would i need a costbehavior interface? If you look at the UML you will see where i am going with this and see if i am implementing observer + Decorator pattern correctly? I think the decorator is correct. since, the pic is not very viewable i will detail the classes here: Beverage class(register observer, remove observer, notify observer, description) these classes are the concrete beverage classes espresso, houseblend,darkroast, decaf(cost,getdescription,setcost,costchanged) interface observer class(update) // cost? interface costbehavior class(cost) // since this changes? condiment decorator class( getdescription) concrete classes that are linked to the 2 interface s and decorator are: milk,mocha,soy,whip(cost,getdescription,update) these are my decorator/ wrapper classes. Thank you.. Is there a way to make this picture bigger?

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  • Flash Builder missing fundamental things

    - by Bart van Heukelom
    All of a sudden Flash Builder 4 is missing all kinds of fundamental things and is generating incorrect errors. I've had the same issue yesterday, where I fixed it by downloading a new Flex SDK and importing that into FB. I did this again, but this time it fixed nothing. I don't think it's something I did, like removing critical references from the build path. The errors also appeared on projects I was not working on at the time. It occurs for ActionScript, Flex and Flex Library projects alike. Update: I find this stack trace in the Flash Builder error log: !ENTRY com.adobe.flexbuilder.project 4 43 2010-05-11 11:55:47.495 !MESSAGE Uncaught exception in compiler !STACK 0 java.lang.NullPointerException at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:2592) at macromedia.asc.parser.VariableBindingNode.evaluate(VariableBindingNode.java:64) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:2233) at macromedia.asc.parser.ListNode.evaluate(ListNode.java:44) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:2578) at macromedia.asc.parser.VariableDefinitionNode.evaluate(VariableDefinitionNode.java:48) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:2310) at macromedia.asc.parser.StatementListNode.evaluate(StatementListNode.java:60) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:2503) at macromedia.asc.parser.WithStatementNode.evaluate(WithStatementNode.java:44) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:2310) at macromedia.asc.parser.StatementListNode.evaluate(StatementListNode.java:60) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:2891) at macromedia.asc.parser.FunctionCommonNode.evaluate(FunctionCommonNode.java:106) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:2905) at macromedia.asc.parser.FunctionCommonNode.evaluate(FunctionCommonNode.java:106) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:3643) at macromedia.asc.parser.ClassDefinitionNode.evaluate(ClassDefinitionNode.java:106) at macromedia.asc.semantics.ConstantEvaluator.evaluate(ConstantEvaluator.java:3371) at macromedia.asc.parser.ProgramNode.evaluate(ProgramNode.java:80) at flex2.compiler.as3.As3Compiler.analyze4(As3Compiler.java:709) at flex2.compiler.CompilerAPI.analyze(CompilerAPI.java:3089) at flex2.compiler.CompilerAPI.analyze(CompilerAPI.java:2977) at flex2.compiler.CompilerAPI.batch2(CompilerAPI.java:528) at flex2.compiler.CompilerAPI.batch(CompilerAPI.java:1274) at flex2.compiler.CompilerAPI.compile(CompilerAPI.java:1496) at flex2.tools.oem.Application.compile(Application.java:1188) at flex2.tools.oem.Application.recompile(Application.java:1133) at flex2.tools.oem.Application.compile(Application.java:819) at flex2.tools.flexbuilder.BuilderApplication.compile(BuilderApplication.java:344) at com.adobe.flexbuilder.multisdk.compiler.internal.ASApplicationBuilder$MyBuilder.mybuild(ASApplicationBuilder.java:276) at com.adobe.flexbuilder.multisdk.compiler.internal.ASApplicationBuilder.build(ASApplicationBuilder.java:127) at com.adobe.flexbuilder.multisdk.compiler.internal.ASBuilder.build(ASBuilder.java:190) at com.adobe.flexbuilder.multisdk.compiler.internal.ASItemBuilder.build(ASItemBuilder.java:74) at com.adobe.flexbuilder.project.compiler.internal.FlexProjectBuilder.buildItem(FlexProjectBuilder.java:480) at com.adobe.flexbuilder.project.compiler.internal.FlexProjectBuilder.build(FlexProjectBuilder.java:306) at com.adobe.flexbuilder.project.compiler.internal.FlexIncrementalBuilder.build(FlexIncrementalBuilder.java:157) at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:627) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:170) at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:201) at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:253) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:256) at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:309) at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:341) at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:140) at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:238) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

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  • Rails Atom builder xml.tag!("activity:object-type") error

    - by Anup
    I am creating a activity stream of my feeds according to the http://activitystrea.ms standard. I am using rails atom builder to create a valid atom feed, but when I use xml.tag!("activity:object-type", "http://activitystrea.ms/schema/1.0/person") the atom feed goes blank.On seeing the source I find the correct xml format from what I have found out the ":object" is giving the problem.

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  • Can't connect IBOutlet in Interface Builder

    - by Dave C
    Hello, I have the following code: @interface AddResident : UIViewController { IBOutlet UITextField *FirstName; IBOutlet UISegmentedControl *Gender; } I can see both of these outlets in interface builder but can only connect the UISegmented control... the other one will not connect to my UITextField on the form. Any help is much appreciated.

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  • Handle a More Navigation Controller in an Interface Builder based TabBar Application

    - by Thomas Joulin
    Hi, I'm still not clear on how and when to use interface builder. I have a tabbar-based application, in which I added 6 navigations controllers. Instead of having 6 tabs, I would like 3 plus a "More" tab which allows the user to configure the tabs he wants. Is there any way to do that with IB ? And if not, how can I move from IB to a code-based tabbar (provided I already set up a class TabBarController which handles shouldAutoRotate:) Thanks in advance !

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  • EF Query Object Pattern over Repository Example

    - by Dale Burrell
    I have built a repository which only exposes IEnumerable based mostly on the examples in "Professional ASP.NET Design Patterns" by Scott Millett. However because he mostly uses NHibernate his example of how to implement the Query Object Pattern, or rather how to best translate the query into something useful in EF, is a bit lacking. I am looking for a good example of an implementation of the Query Object Pattern using EF4.

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  • Reporter Builder 2.0

    - by ozsenegal
    I am developing a simple report in report builder,and i cant fix rows height bug. When a row has just one line it dont fit the text,and a whiteline appears below it,because others rows in the same grid ,has 2 or more lines. I try to change properties:"can shrink" and "can grow",but it doesnt solve. Any ideas?

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  • How to access Active Directory using C++Builder?

    - by Gus Brown
    I need to get a list of user names from Active Directory using C++Builder. I know I could shell out to batch file and run the csvde.exe command but surely there is a nicer way using a library or something, right? Are there any C++ libraries? (hopefully with examples?) Many thanks! -Dan

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  • PHP general form generator/builder

    - by Ehsan
    I'm looking for an open source php form builder or form generator to add/edit/delete/search records? I have to create a simple manager for some records, it's a common application that should be found easily, but I can't find any good code/class/application/etc :( Any help is appreciated.

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  • Count number of occurrences of a pattern in a file (even on same line)

    - by jrdioko
    When searching for number of occurrences of a string in a file, I generally use: grep pattern file | wc -l However, this only finds one occurrence per line, because of the way grep works. How can I search for the number of times a string appears in a file, regardless of whether they are on the same or different lines? Also, what if I'm searching for a regex pattern, not a simple string? How can I count those, or, even better, print each match on a new line?

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  • segemented control in iphone not appearing as in interface builder

    - by zecougar
    here is what i see in IB and here is what appears in the simulator i've used a segmented control with style = "Bezelled". When i change the style to "Bar", IB and simulator are consistent in the display. the style is set in interface builder and not in code, if that matters Also - the edges look rather ugly in the simulator. not what i expected even when it rendered incorrectly. Thanks in advance

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  • UIViewController takes up entire screen in Interface Builder

    - by Sheehan Alam
    I have a NIB with a UIView that contains some UILabels, UIButtons etc. and a UIViewController that is loading a detached NIB. I want the UIViewController to be positioned below my UIView, but whenever I add it in Interface Builder it takes up the whole screen, and my UIView becomes part of the UIViewController. How can I make sure UIViewController appears below the UIView?

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