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  • How to determine if a device is SATA driven and will be affect by the Sandy Bridge Intel Issue?

    - by joelhaus
    Looking to buy a higher-end Windows 7 laptop, but I'm concerned about the issue with the Intel Sandy Bridge chipset. Otherwise, my price range covers laptops within the latest (Sandy Bridge) generation of the Core i7 family. I understand that there is an issue with SATA ports 2-5 and I use a Windows Home Server over a WiFi connection to share files and backup my PC. The other storage devices that I will use (less frequently) are the built-in DVD-RW disc drive and various devices hooked up to the USB ports (i.e. Android devices, iPod, etc.). The question: Will this setup be negatively impacted by the problem Intel reported about Sandy Bridge? Given this information, is it unwise to purchase a laptop that has this flaw? I really don't know how to determine whether a device is SATA driven or not, so hoping someone can shed some light on this too. Thanks!

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  • Why do I see the weird backspace behaviour on my shell sometimes?

    - by Lazer
    I use bash shell and sometimes all of a sudded, my Backspace key stops working (when this happens Ctrl + Backspace still works fine) I am not sure why this happens, but it also carries over to any vim sessions that I use from the shell. To my surprise, getting a fresh shell does not help, and the problem seems to go away as abruptly as it started. This is what the typed characters look like, each Backspace keypress is shown by a ^? on the shell $ cat filem^?namr^?e Does anybody have a clue what might be happening? How can I restore the normal behaviour?

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  • Strange strace and setuid behaviour: permission denied under strace, but not running normally.

    - by Autopulated
    This is related to this question. I have a script (fix-permissions.sh) that fixes some file permissions: #! /bin/bash sudo chown -R person:group /path/ sudo chmod -R g+rw /path/ And a small c program to run this, which is setuided: #include "sys/types.h" #include "unistd.h" int main(){ setuid(geteuid()); return system("/path/fix-permissions.sh"); } Directory: -rwsr-xr-x 1 root root 7228 Feb 19 17:33 fix-permissions -rwx--x--x 1 root root 112 Feb 19 13:38 fix-permissions.sh If I do this, everything seems fine, and the permissions do get correctly fixed: james $ sudo su someone-else someone-else $ ./fix-permissions but if I use strace, I get: someone-else $ strace ./fix-permissions /bin/bash: /path/fix-permissions.sh: Permission denied It's interesting to note that I get the same permission denied error with an identical setup (permissions, c program), but a different script, even when not using strace. Is this some kind of heureustic magic behaviour in setuid that I'm uncovering? How should I figure out what's going on? System is Ubuntu 10.04.2 LTS, Linux 2.6.32.26-kvm-i386-20101122 #1 SMP

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  • Why do Windows 7 & 8 have different default behaviour when trying to modify contents of protected folder

    - by Ben
    Here's the situation: I have a Windows 7 PC and a Windows 8 PC and I'm logged in as the same domain user on both machines. My domain user is in the local Administrator group on both. When I run cmd.exe on each machine and then attempt to do this (also on both machines) mkdir "c:\Program Files\cheese" the Windows 8 PC gives an "Access Denied" error, while it works fine on the Windows 7 PC. I understand that C:\Program Files is a protected folder and I'm not interested in a debate on the morals of writing to such a folder directly. But I am interested in understanding what exactly has changed in Windows 8 to cause this. I don't seem to be able to find anything that acknowledges or explains this change in behaviour in Windows 8.

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  • What's the behaviour when opening a group of files at once?

    - by Leo King
    I selected a group of .odt files, right-clicked the first one and selected open. I would have thought they would open in alphabetical order, but as the second screenshot shows, they're not - the one with "2014-11-13" opens before "2013-10-23". And then when I select the whole group and press Enter, they open in order - and sometimes they don't. What's the behaviour when you right-click and open for a batch of files? Does it start with the one you selected and pick random files in the list to open next?

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  • How can we tell what driven the Private bytes spiking.

    - by ronin
    I have websites running on .Net Framework 2.0 environment. For recent every day my website becomes slow at certain time and I need to recycle my app pool. I checked the log file found that the private bytes will spike during that time slot. Through some research I already know that the managed code and unmanaged code consists of Privates and we can identify which one cause the spike based on "Bytes in all heaps" counter. But I can't find a way to dig deeper. Is there any way that I can find out what driven my private bytes spike? How can we see what the private bytes are being used for? Thanks, Ronin

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  • Tuesday at Oracle OpenWorld 2012 - Must See Session: “Oracle Fusion Applications: Best Practices in Integration Design Patterns”

    - by Lionel Dubreuil
    Don’t miss this “CON8685 - Oracle Fusion Applications: Best Practices in Integration Design Patterns “ session: Speakers: Rajesh Raheja - Senior Director, Development, Oracle Ravi Sankaran - Director, Applications Development, Oracle Date: Tuesday, Oct 2 Time: 1:15 PM - 2:15 PM Location: Palace Hotel - Telegraph Oracle Fusion Applications provide various ways to integrate their functional capabilities with other Oracle applications as well as third-party and legacy applications. In this session, you will learn the patterns used when communicating with Oracle Fusion Applications with a SOA approach. It addresses items related to identifying the integration artifacts available, also known as assets, in Oracle Enterprise Repository; how to invoke synchronous and asynchronous Web services; importing and exporting bulk data; and any integration issues to look out for. The patterns will be applicable to on-premises and SaaS/cloud deployment modes and are indicated as such. Objectives for this session are to: Highlight the various ways to integrate with Oracle Fusion Applications Showcase use of Oracle Fusion Middleware technologies for integration Describe best practices and design patterns for integration Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";}

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  • How can I choose a Webapp UI Design/dev collaborative tool?

    - by Cheeso
    I am working with a team that's building a webapp for internal use in an enterprise. It's basically a workflow app at heart, where there's a single "request". Each request flows through various stages, and at each stage, there's a person or role that is responsible for moving the request to the next stage. "Moving" the request to the next stage might involve adding more data, validating things, gathering input from some external source and correlating it to the data in the request, and so on. The workflow engine has been selected. The UI for the various roles and stakeholders is being designed. We have a distributed group of stakeholders. I'd like to employ a collaborative design/dev effort, where devs can produce and stand-up mockups or even working prototypes, then solicit feedback on those things. In a centralized team this could be done via design review meetings, with everyone gathered round a screen projector. That just is not going to work for us. So what I'd like is an app that can help with this. Any recommendations on apps or how to choose?

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  • Which version management design methodology to be used in a Dependent System nodes?

    - by actiononmail
    This is my first question so please indicate if my question is too vague and not understandable. My question is more related to High Level Design. We have a system (specifically an ATCA Chassis) configured in a Star Topology, having Master Node (MN) and other sub-ordinate nodes(SN). All nodes are connected via Ethernet and shall run on Linux OS with other proprietary applications. I have to build a recovery Framework Design so that any software entity, whether its Linux, Ramdisk or application can be rollback to previous good versions if something bad happens. Thus I think of maintaining a State Version Matrix over MN, where each State(1,2....n) represents Good Kernel, Ramdisk and application versions for each SN. It may happen that one SN version can dependent on other SN's version. Please see following diagram:- So I am in dilemma whether to use Package Management Methodology used by Debian Distributions (Like Ubuntu) or GIT repository methodology; in order to do a Rollback to previous good versions on either one SN or on all the dependent SNs. The method should also be easier for upgrading SNs along with MNs. Some of the features which I am trying to achieve:- 1) Upgrade of even single software entity is achievable without hindering others. 2) Dependency checks must be done before applying rollback or upgrade on each of the SN 3) User Prompt should be given in case dependency fails.If User still go for rollback, all the SNs should get notification to rollback there own releases (if required). 4) The binaries should be distributed on SNs accordingly so that recovery process is faster; rather fetching every time from MN. 5) Release Patches from developer for bug fixes, feature enhancement can be applied on running system. 6) Each version can be easily tracked and distinguishable. Thanks

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  • What is the right way to structure HTML and CSS?

    - by Meke
    So, I'm a script monkey at the core. Lately I seem to get stuffed into doing design too for some odd reason and, well, let's just say I should probably have studied better. Either way - What I ask is, what's the Right way to structure a website? This one has a header with links, then a block with tabs, right under another block which consists of two parts and under those a few others who I'm not at yet. However, the thing is, I need to make a block that consists of two parts that are in the same box but structured independently. I'll try to draw it up. Browser window..................-[]X ------------------------------------ |.................Header Links Here| ||Tab|Tab|Tab|_____________........| ||Tab content.............|Small...| ||........................|Section.| ||---Line signing new section------| ||........................|Another.| ||..Content Area..........|Small...| ||........................|Section.| ------------------------------------ My issue is in the division of small sections and tab/content areas. I tried using floats, making them as tables, aligning and whatnot. The putting float:left on both tables worked. Kinda. Until I tried to resize the window. So, how do you PROPERLY structure a site like this? three divs and tables? Something else? I'll clarify this again: It's the Code to use to create the look above that I'm trying to figure out the proper way to do, not the design As requested here's the current structure I have <div class="container"> <div class="topBlock"> //Header Links Here </div> <div class="inputBlock"> <ul id="tabs"> <li><a href="#strict">Strict</a></li> <li><a href="#flex">Flex</a></li> <li><a href="#multiStep">Multi-Step</a></li> </ul> <div id="strict" class="tabContent"> <table class="tableLeft"> <tr> <td>From</td> </tr> <tr> <td><input id="inputBlockFrom" type="text" placeholder="FROM"/></td> </tr> <tr> <td>To</td> </tr> <tr> <td><input id="inputBlockTo" type="text" placeholder="TO"/></td> </tr> </table> <table class="tableRight"> <tr> <td>Leave</td> </tr> <tr> <td><input id="inputBlockLeave" type="text" name="leave" placeholder="LEAVE"/></td> <td><input id="inputBlockOne" type="radio" name="one"/></td> <td>One</td> </tr> <tr> <td>Return</td> </tr> <tr> <td><input id="inputBlockReturn" type="text" name="return" placeholder="RETURN"/></td> <td><input id="inputBlockBut" type="radio" name="one" checked/></td> <td>Return</td> </tr> <tr> <td><input id="inputBlockSubmit" type="submit" value="Search"/></td> </tr> </table> </div> <div id="flex" class="tabContent"> Test Two </div> <div id="multiStep" class="tabContent"> Test Three </div> </div> <div class="mapBlock tabContent"> <table class="tableLeft"> <tr><td> <div id="map" class="google_map"></div> </td></tr> </table> <table class="tableRight smallTable"> <tr> <td>Distance</td> </tr> <tr> <td>[-------------|------------]</td> //Slider to be </tr> </table> <table class="tableRight smallTable"> <tr> <td>Choice / Choice</td> </tr> </table> <table class="tableRight"> <tr> <td>Show:</td> </tr> <tr> <td><input type="radio"/></td> <td>Price</td> <td><input type="radio"/></td> <td>Button!</td> </tr> <tr> <td><input type="radio"/></td> </tr> <tr> <td><input type="radio"/></td> </tr> </table> </div> </div> </body> Sorry if it's messed up in the whitespacing somewhere.. The CSS: body { font-size: 80%; font-family: 'Lucida Grande', Verdana, Arial, Sans-Serif; background-color: #e2edff; } .container { margin: 5px 5px 5px 5px; padding: 5px 5px 5px 5px; } .pageBlock { /* To future me: This class is for One Full Screen ideas */ min-height: 300px; } .topBlock { text-align: right; color: #000000; } .topBlock a { text-decoration: none; color: #000000; } .tableLeft { width: 75%; float: left; border-right: dotted 2px black; } .tableRight { float: left; overflow: auto; } .smallTable { border-bottom: 1px dotted #c9c3ba; } .google_map { height: 270px; width: 100%; }

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  • How to Link VS2010 Database Project and LINQ to SQL

    - by Jason
    As I am working with the new database projects in VS2010, and as I am learning LINQ to SQL, I am curious as to the best way to link the two groups of information so that when I update one, the other updates along with it. From my research here at SO, as well as in Google, it appears the general rule of thumb is: "Build the database, and then create your LINQ to SQL classes." Of course, if I make a change in my database, the LINQ to SQL doesn't update automatically and I have to do it by hand. This is fairly simple right now as my database is small, but I am curious if there is an easier way for this to happen. In addition, the LINQ to SQL tool is pretty nice. The ability to create tables, add associations, and even create inheritance is very simple. As my second question, I am curious as to whether or not VS2010 can work the other way - I design the database in the DBLM file and then link it back to my database project. I appreciate any help with either of these two questions. I'm really interested in making this as easy as possible to reduce errors during development and improve the speed at which changes can be made.

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  • ReSharper - Possible Null Assignment when using Microsoft.Contracts

    - by HVS
    Is there any way to indicate to ReSharper that a null reference won't occur because of Design-by-Contract Requires checking? For example, the following code will raise the warning (Possible 'null' assignment to entity marked with 'NotNull' attribute) in ReSharper on lines 7 and 8: private Dictionary<string, string> _Lookup = new Dictionary<string, string>(); public void Foo(string s) { Contract.Requires(!String.IsNullOrEmpty(s)); if (_Lookup.ContainsKey(s)) _Lookup.Remove(s); } What is really odd is that if you remove the Contract.Requires(...) line, the ReSharper message goes away. Update I found the solution through ExternalAnnotations which was also mentioned by Mike below. Here's an example of how to do it for a function in Microsoft.Contracts: Create a directory called Microsoft.Contracts under the ExternalAnnotations ReSharper directory. Next, Create a file called Microsoft.Contracts.xml and populate like so: <assembly name="Microsoft.Contracts"> <member name="M:System.Diagnostics.Contracts.Contract.Requires(System.Boolean)"> <attribute ctor="M:JetBrains.Annotations.AssertionMethodAttribute.#ctor"/> <parameter name="condition"> <attribute ctor="M:JetBrains.Annotations.AssertionConditionAttribute.#ctor(JetBrains.Annotations.AssertionConditionType)"> <argument>0</argument> </attribute> </parameter> </member> </assembly> Restart Visual Studio, and the message goes away!

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  • Legit? Two foreign keys referencing the same primary key.

    - by Ryan
    Hi All, I'm a web developer and have recently started a project with a company. Currently, I'm working with their DBA on getting the schema laid out for the site, and we've come to a disagreement regarding the design on a couple tables, and I'd like some opinions on the matter. Basically, we are working on a site that will implement a "friends" network. All users of the site will be contained in a table tblUsers with (PersonID int identity PK, etc). What I am wanting to do is to create a second table, tblNetwork, that will hold all of the relationships between users, with (NetworkID int identity PK, Owners_PersonID int FK, Friends_PersonID int FK, etc). Or conversely, remove the NetworkID, and have both the Owners_PersonID and Friends_PersonID shared as the Primary key. This is where the DBA has his problem. Saying that "he would only implement this kind of architecture in a data warehousing schema, and not for a website, and this is just another example of web developers trying to take the easy way out." Now obviously, his remark was a bit inflammatory, and that have helped motivate me to find an suitable answer, but more so, I'd just like to know how to do it right. I've been developing databases and programming for over 10 years, have worked with some top-notch minds, and have never heard this kind of argument. What the DBA is wanting to do is instead of storing both the Owners_PersonId and Friends_PersonId in the same table, is to create a third table tblFriends to store the Friends_PersonId, and have the tblNetwork have (NetworkID int identity PK, Owner_PersonID int FK, FriendsID int FK(from TBLFriends)). All that tblFriends would house would be (FriendsID int identity PK, Friends_PersonID(related back to Persons)). To me, creating the third table is just excessive in nature, and does nothing but create an alias for the Friends_PersonID, and cause me to have to add (what I view as unneeded) joins to all my queries, not to mention the extra cycles that will be necessary to perform the join on every query. Thanks for reading, appreciate comments. Ryan

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  • Database structure - is mySQL the right choice?

    - by Industrial
    Hi everyone, We are currently planning the database structure of a quite complex e-commerce web app that has flexibility as it's main cornerstone. Our app features a large amount of data (products) and we have run into a slight headache trying to keep performance high without compromizing normalization rules in the database, or leaving our highly beloved flexibility concept behind when integrating product options (also widely known as product attributes or parameters). Based on various references and sources available, we have made up lists on pros and cons of all major and well known database patterns to solve this. After comparing these, we have come up with two final alternatives: EAV (Entity-attribute-value model) : Pros: Database is used for all sorting. Cons: All related queries will include a number of joins between multiple tables in order to complete the collection of data. SLOB (Serialized LOB, also known as Facade?) : Pros: Very flexible. Keeping the number of necessary joins low compared to a EAV design pattern. Easy to update/add/remove data from each product. Cons: All sorting will be done by the application instead of the database. Will use lots of performance (memory?) when big datasets is processed by a large number of users. Our main questions: Which pattern/structure would you use, or maybe even a different solution? Is there better databases besides mySQL available nowadays to accomplish what we want? Thanks a lot! Reference: http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters

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  • Invoice & Invoice lines: How do you store customer address information?

    - by elviejo
    Hi I'm developing an invoicing application. So the general idea is to have two tables: Invoice (ID, Date, CustomerAddress, CustomerState, CustomerCountry, VAT, Total); InvoiceLine (Invoice_ID, ID, Concept, Units, PricePerUnit, Total); As you can see this basic design leads to a lot of repetiton of records where the client will have the same addrres, state and country. So the alternative is to have an address table and then make a relationship Address<-Invoice. However I think that an invoice is immutable document and should be stored just the way it was first made. Sometimes customers change their addresses, or states and if it was coming from an Address catalog that will change all the previously made invoices. So What is your experience? How is the customer address stored in an invoice? In the Invoice table? an Address Table? or something else? Can you provide pointers to a book, article or document where this is discussed in further detail?

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  • Taking the data mapper approach in Zend Framework

    - by Seeker
    Let's assume the following tables setup for a Zend Framework app. user (id) groups (id) groups_users (id, user_id, group_id, join_date) I took the Data Mapper approach to models which basically gives me: Model_User, Model_UsersMapper, Model_DbTable_Users Model_Group, Model_GroupsMapper, Model_DbTable_Groups Model_GroupUser, Model_GroupsUsersMapper, Model_DbTable_GroupsUsers (for holding the relationships which can be seen as aentities; notice the "join_date" property) I'm defining the _referenceMap in Model_DbTable_GroupsUsers: protected $_referenceMap = array ( 'User' => array ( 'columns' => array('user_id'), 'refTableClass' => 'Model_DbTable_Users', 'refColumns' => array('id') ), 'App' => array ( 'columns' => array('group_id'), 'refTableClass' => 'Model_DbTable_Groups', 'refColumns' => array('id') ) ); I'm having these design problems in mind: 1) The Model_Group only mirrors the fields in the groups table. How can I return a collection of groups a user is a member of and also the date the user joined that group for every group? If I just added the property to the domain object, then I'd have to let the group mapper know about it, wouldn't I? 2) Let's say I need to fetch the groups a user belongs to. Where should I put this logic? Model_UsersMapper or Model_GroupsUsersMapper? I also want to make use of the referencing map (dependent tables) mechanism and probably use findManyToManyRowset or findDependentRowset, something like: $result = $this->getDbTable()->find($userId); $row = $result->current(); $groups = $row->findManyToManyRowset( 'Model_DbTable_Groups', 'Model_DbTable_GroupsUsers' ); This would produce two queries when I could have just written it in a single query. I will place this in the Model_GroupsUsersMapper class. An enhancement would be to add a getGroups method to the Model_User domain object which lazily loads the groups when needed by calling the appropriate method in the data mapper, which begs for the second question. Should I allow the domain object know about the data mapper?

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  • structured vs. unstructured data in db

    - by Igor
    the question is one of design. i'm gathering a big chunk of performance data with lots of key-value pairs. pretty much everything in /proc/cpuinfo, /proc/meminfo/, /proc/loadavg, plus a bunch of other stuff, from several hundred hosts. right now, i just need to display the latest chunk of data in my UI. i will probably end up doing some analysis of the data gathered to figure out performance problems down the road, but this is a new application so i'm not sure what exactly i'm looking for performance-wise just yet. i could structure the data in the db -- have a column for each key i'm gathering. the table would end up being O(100) columns wide, it would be a pain to put into the db, i would have to add new columns if i start gathering a new stat. but it would be easy to sort/analyze the data just using SQL. or i could just dump my unstructured data blob into the table. maybe three columns -- host id, timestamp, and a serialized version of my array, probably using JSON in a TEXT field. which should I do? am i going to be sorry if i go with the unstructured approach? when doing analysis, should i just convert the fields i'm interested in and create a new, more structured table? what are the trade-offs i'm missing here?

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  • Database migration pattern for Java?

    - by Eno
    Im working on some database migration code in Java. Im also using a factory pattern so I can use different kinds of databases. And each kind of database im using implements a common interface. What I would like to do is have a migration check that is internal to the class and runs some database schema update code automatically. The actual update is pretty straight forward (I check schema version in a table and compare against a constant in my app to decide whether to migrate or not and between which versions of schema). To make this automatic I was thinking the test should live inside (or be called from) the constructor. OK, fair enough, that's simple enough. My problem is that I dont want the test to run every single time I instantiate a database object (it runs a query so having it run on every construction is not efficient). So maybe this should be a class static method? I guess my question is, what is a good design pattern for this type of problem? There ought to be a clean way to ensure the migration test runs only once OR is super-efficient.

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  • fluent nHibernate mapping of subclassed structure

    - by Codezy
    I have a workflow class that has a collection of phases, each phase has a collection of tasks. You can design a workflow that will be used by many engagements. When used in engagement I want to be able to add properties to each class (workflow, phase, and task). For example a task in the designer does not have people assigned, but a task in an engagement would need extra properties like who is assigned to it. I have tried many different approaches using subclasses or interfaces but I just can't get it to map the way I want. Currently I have the engagement level versions as subclasses, but I can't get Engagement phases to map to engagement workflows. Public Class WorkflowMapping Inherits ClassMap(Of Workflow) Sub New() Id(Function(x As Workflow) x.Id).Column("Workflow_Id").GeneratedBy.Identity() Map(Function(x As Workflow) x.Description) Map(Function(x As Workflow) x.Generation) Map(Function(x As Workflow) x.IsActive) HasMany(Function(x As Workflow) x.Phases).Cascade.All() End Sub End Class Public Class EngagementWorkflowMapping Inherits SubclassMap(Of EngagementWorkflow) Sub New() Map(Function(x As EngagementWorkflow) x.ClientNo) Map(Function(x As EngagementWorkflow) x.EngagementNo) End Sub End Class How would you approach mapping this in fluent (or hbm) so that you could load just the workflow base class when designing the flow, or the engagement subclass versions of each when being used by an engagement?

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  • Flexible Decorator Pattern?

    - by Omar Kooheji
    I was looking for a pattern to model something I'm thinking of doing in a personal project and I was wondering if a modified version of the decorator patter would work. Basicly I'm thinking of creating a game where the characters attributes are modified by what items they have equiped. The way that the decorator stacks it's modifications is perfect for this, however I've never seen a decorator that allows you to drop intermediate decorators, which is what would happen when items are unequiped. Does anyone have experience using the decorator pattern in this way? Or am I barking up the wrong tree? Clarification To explain "Intermediate decorators" if for example my base class is coffe which is decorated with milk which is decorated with sugar (using the example in Head first design patterns) milk would be an intermediate decorator as it decorates the base coffee, and is decorated by the sugar. Yet More Clarification :) The idea is that items change stats, I'd agree that I am shoehorning the decorator into this. I'll look into the state bag. essentially I want a single point of call for the statistics and for them to go up/down when items are equiped/unequiped. I could just apply the modifiers to the characters stats on equiping and roll them back when unequiping. Or whenever a stat is asked for iterate through all the items and calculate the stat. I'm just looking for feedback here, I'm aware that I might be using a chainsaw where scissors would be more appropriate...

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  • Generics with constraints hierarchy

    - by devoured elysium
    I am currently facing a very disturbing problem: interface IStateSpace<Position, Value> where Position : IPosition // <-- Problem starts here where Value : IValue // <-- and here as I don't { // know how to get away this // circular dependency! // Notice how I should be // defining generics parameters // here but I can't! Value GetStateAt(Position position); void SetStateAt(Position position, State state); } As you'll down here, both IPosition, IValue and IState depend on each other. How am I supposed to get away with this? I can't think of any other design that will circumvent this circular dependency and still describes exactly what I want to do! interface IState<StateSpace, Value> where StateSpace : IStateSpace where Value : IValue { StateSpace StateSpace { get; }; Value Value { get; set; } } interface IPosition { } interface IValue<State> where State : IState { State State { get; } } Basically I have a state space IStateSpace that has states IState inside. Their position in the state space is given by an IPosition. Each state then has one (or more) values IValue. I am simplifying the hierarchy, as it's a bit more complex than described. The idea of having this hierarchy defined with generics is to allow for different implementations of the same concepts (an IStateSpace will be implemented both as a matrix as an graph, etc). Would can I get away with this? How do you generally solve this kind of problems? Which kind of designs are used in these cases? Thanks

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  • [Smalltalk] Store List of Instruction

    - by Luciano Lorenti
    Hi all, I have a design Problem. i have a Drawer class wich invokes a serie of methods of a kind-of-brush class and i have a predefined shapes which i want to draw. Each shape uses a list of instance methods from the drawer. I can have more than 1 brush object. I want to add custom shapes on runtime in the drawer instance, especifying the list of methods of the new shape. i've created a class method for every predefined shape that returns a BlockClosure with the instruccions. Obviously i have to give to each BlockClosure the brush object as parameter. I imagine a collection with all the BlockClosures in each instance of the Drawer Class. Maybe i can inherit a SequenceableCollection and make a instruccion collection. Each element of the collection it's a instruction and i give the brush object when i instance this new collection. I really don't know the best way to store these steps. (Maybe a shared variable?)

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  • What is the equivalent of .NET events in Ruby?

    - by Gishu
    The problem is very simple. An object needs to notify some events that might be of interest to observers. When I sat to validate a design that I cooked up now in Ruby just to validate it.. I find myself stumped as to how to implement the object events. In .Net this would be a one-liner.. .Net also does handler method signature verification,etc. e.g. // Object with events public delegate void HandlerSignature(int a); public event HandlerSignature MyEvent; public event HandlerSignature AnotherCriticalEvent; // Client MyObject.MyEvent += new HandlerSignature(MyHandlerMethod); // MyHandlerMethod has same signature as delegate Is there an EventDispatcher module or something that I am missing that I can strap on to a Ruby class ? Hoping for an answer that plays along with Ruby's principle of least surprise. An event would be the name of the event plus a queue of [observer, methodName] objects that need to be invoked when the event takes place.

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  • Can the Diamond Problem be really solved?

    - by Mecki
    A typical problem in OO programming is the diamond problem. I have parent class A with two sub-classes B and C. A has an abstract method, B and C implement it. Now I have a sub-class D, that inherits of B and C. The diamond problem is now, what implementation shall D use, the one of B or the one of C? People claim Java knows no diamond problem. I can only have multiple inheritance with interfaces and since they have no implementation, I have no diamond problem. Is this really true? I don't think so. See below: [removed vehicle example] Is a diamond problem always the cause of bad class design and something neither programmer nor compiler needs to solve, because it shouldn't exist in the first place? Update: Maybe my example was poorly chosen. See this image Of course you can make Person virtual in C++ and thus you will only have one instance of person in memory, but the real problem persists IMHO. How would you implement getDepartment() for GradTeachingFellow? Consider, he might be student in one department and teach in another one. So you can either return one department or the other one; there is no perfect solution to the problem and the fact that no implementation might be inherited (e.g. Student and Teacher could both be interfaces) doesn't seem to solve the problem to me.

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  • Explaining the need to avoid horizontal scroll

    - by Bradley Herman
    I need help explaining to my boss why her design is poor on a client's website. She has no knowledge of the web, and it can be difficult as a web developer working with a woman who is a graphic designer (not even a web designer really). On a current site she has designed, an image bar "needs" to be ~1200px according to her, though it isn't necessary with the content. A quick sketch to illustrate what's going on: As you see, the banner spills out past the 960px of the content and as wide as 1200px. This creates a horizontal scroll when all the content is viewable within the 960px wide viewport. I need to make this an <img and not a CSS background because it's a jQuery slideshow that fades from image to image. I think this is a big problem because a lot of people are going to get a horizontal scroll bar imposed in their browser when they're still able to see all the relevant content. She thinks no one will notice and it'll be fine; I think it's very bad practice and confusing to the end user. How do I explain the problem to her?

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