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• Logic in Entity Components Systems

  - by aaron

  I'm making a game that uses an Entity/Component architecture basically a port of Artemis's framework to c++,the problem arises when I try to make a PlayerControllerComponent, my original idea was this. class PlayerControllerComponent: Component { public: virtual void update() = 0; }; class FpsPlayerControllerComponent: PlayerControllerComponent { public: void update() { //handle input } }; and have a system that updates PlayerControllerComponents, but I found out that the artemis framework does not look at sub-classes the way I thought it would. So all in all my question here is should I make the framework aware of subclasses or should I add a new Component like object that is used for logic.

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• Logic in Entity Components Sytems

  - by aaron

  I'm making a game that uses an Entity/Component architecture basically a port of Artemis's framework to c++,the problem arises when I try to make a PlayerControllerComponent, my original idea was this. class PlayerControllerComponent: Component { public: virtual void update() = 0; }; class FpsPlayerControllerComponent: PlayerControllerComponent { public: void update() { //handle input } }; and have a system that updates PlayerControllerComponents, but I found out that the artemis framework does not look at sub-classes the way I thought it would. So all in all my question here is should I make the framework aware of subclasses or should I add a new Component like object that is used for logic.

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• OnTouch event consumes click event and prevents execution in parent

  - by Taig

  I'm having a FrameLayout that has an extended ImageView (github) as a child. When I set an onClick()-Event to the FrameLayout it won't be triggered. The reason appears to be the onTouch() method's return value. If I set the ACTION_DOWN's return value to false the event is passed along properly - but then the Multitouch functionalities break. Also running performClick() in the ACTION_UP event comes to nothing. How to handle those events correctly?

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• performing a javascript event without triggering that event handler

  - by bento

  In my latest code, I have an event handler for a focus on a textarea. When the user clicks on the textarea, that event-handler is triggered which sets some other DOM states based on the selected textarea. However, elsewhere in my program I want to programmatically set the focus of the textarea without triggering that event handler. I know Backbone, for instance, has a way to silently perform an action. My only pseudo-solution is to temporarily set a variable: var silence = true; And then, in my event handler, only perform the logic if silence is false. The handler is still triggered, but the logic doesn't run. Does anyone else know of better strategies for this?

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• Inserting THEAD element into embedded HTML using jQuery

  - by robalot

  I'm trying to use jQuery to insert HTML into a table element. I've been messing variations of the selector (below) with no luck. Can someone help me? My Selector: $j('#ctl00_body_gridData_dom').children('table:first').append("<thead><tr><td colspan='6'>&nbsp;</td><td align='center' colspan='7'>EM SPECS</td><td align='center' colspan='7'>FISH</td><td colspan='11'>&nbsp;</td></tr></thead>"); Here's what I am trying to do... I want to insert this: <thead> <tr> <td colspan="6"> &nbsp; </td> <td align="center" colspan="7"> EM SPECS </td> <td align="center" colspan="7"> FISH </td> <td colspan="11"> &nbsp; </td> </tr> </thead> The sample below is what I want the end result to look like... So It Looks Like This: Jquery Event Pool <table id="ctl00_body_gridData" style="width: 2000px; -moz-user-select: none;" border="1" cellpadding="0" cellspacing="0"> <tbody> <tr> <td id="ctl00_body_gridData_dom" class="GridData" style="vertical-align: top; height: 245px;" valign="top"> <table style="width: 100%;" border="0" cellpadding="0" cellspacing="0"> <thead> <tr> <td colspan="6"> &nbsp; </td> <td align="center" colspan="7"> EM SPECS </td> <td align="center" colspan="7"> FISH </td> <td colspan="11"> &nbsp; </td> </tr> </thead> <tbody> <tr id="ctl00_body_gridData_top_head" class="headerlineGrid"> <td width="16"> <div style="width: 16px;"></div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,4,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,4,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,0,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,4,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,4,0)" style="width: 89px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 89px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Work<br>Package</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,6,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,6,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,1,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,6,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,6,0)" style="width: 62px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 62px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Work<br>Order</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,9,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,9,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,2,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,9,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,9,0)" style="width: 66px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 66px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> FCR<br>Group</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,12,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,12,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,3,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,12,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,12,0)" style="width: 105px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 105px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center">Contractor</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,15,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,15,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,4,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,15,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,15,0)" style="width: 159px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 159px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Capital/Expense<br>Group</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,19,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,19,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,5,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,19,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,19,0)" style="width: 99px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 99px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center">Cost Type</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,20,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,20,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,6,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,20,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,20,0)" style="width: 81px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 81px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Commit<br>Dollars</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,21,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,21,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,7,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,21,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,21,0)" style="width: 81px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 81px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Commit<br>Hours</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,22,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,22,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,8,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,22,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,22,0)" style="width: 86px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 86px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Commit<br>Quantity</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,23,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,23,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,9,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,23,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,23,0)" style="width: 76px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 76px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Control<br>Budget</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,24,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,24,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,10,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,24,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,24,0)" style="width: 46px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 46px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center">FTC</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,25,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,25,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,11,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,25,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,25,0)" style="width: 88px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 88px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Total<br>Forecast</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,26,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,26,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,12,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,26,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,26,0)" style="width: 50px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 50px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br>COB</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,27,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,27,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,13,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,27,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,27,0)" style="width: 49px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 49px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br>CCB</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,28,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,28,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,14,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,28,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,28,0)" style="width: 81px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 81px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br> Commit<br>$</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,29,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,29,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,15,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,29,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,29,0)" style="width: 81px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 81px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br> Commit<br>Hours</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,30,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,30,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,16,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,30,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,30,0)" style="width: 86px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 86px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br> Commit<br>Quantity</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,31,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,31,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,17,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,31,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,31,0)" style="width: 95px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 95px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br>% Compl.</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,32,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,32,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,18,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,32,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,32,0)" style="width: 105px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 105px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Contractor<br>CFTC</td> </tr> </tbody> </table> </div> </td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_0" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Engineering</td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_1" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Pipe</td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_2" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Concrete</td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_3" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Insulation</td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_4" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Buildings</td> </tr> </tbody> </table> </td> </tr> </tbody> </table> </body> </html>

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• Replace Javascript click event with timed event?

  - by Rik

  Hi, I've found some javascript code that layers photos on top of each other when you click on them. Rather than having to click I'd like the function to automatically run every 5 seconds. How can I change this event to a timed one: $('a#nextImage, #image img').click(function(event){ Full code below. Thanks <script type="text/javascript"> $(document).ready(function(){ $('#description').css({'display':'block'}); $('#image img').hover(function() { $(this).addClass('hover'); }, function() { $(this).removeClass('hover'); }); $('a#nextImage, #image img').click(function(event){ event.preventDefault(); $('#description p:first-child').css({'visibility':'hidden'}); if($('#image img.current').next().length){ $('#image img.current').removeClass('current').next().fadeIn('normal').addClass('current').css({'position':'absolute'}); }else{ $('#image img').removeClass('current').css({'display':'none'}); $('#image img:first-child').fadeIn('normal').addClass('current').css({'position':'absolute'}); } if($('#image img.current').width()>=($('#page').width()-100)){ xPos=170; }else{ do{ xPos = 120 + (Math.floor(Math.random()*($('#page').width()-100))); }while(xPos+$('#image img.current').width()>$('#page').width()); } if($('#image img.current').height()>=300){ yPos=0; }else{ do{ yPos = Math.floor(Math.random()*300); }while(yPos+$('#image img.current').height()>300); } $('#image img.current').css({'left':xPos,'top':yPos}); }); });

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• Version hash to solve Event Sourcing problems

  - by SystematicFrank

  The basic examples I have seen about Event Sourcing do not deal with out of order events, clock offsets in different systems and late events from system partitions. I am wondering if more polished Event Sourcing implementations rely on a version stamp of modified objects? For example, assuming that the system is rendering the entity Client with version id ABCD1234. If the user modifies the entity, the system will create an event with the modified fields AND the version id reference to which version it applies. Later the event responder would detect out of order events and merge them.

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• Computer Components

  - by Martin

  What is the role of a motherboard in terms of how components communicate with the processor (via the system busses). Therefore, for each component, which communication bus is involved and what is the route that data takes from the component to the processor, including; The bus name Whether bus is serial or parallel The name of any bridges involved Also, what is the the role of a bridge The components are: Internal components: Floppy Drive, Hard Drive, CD/DVD Drive, Memory, Processor Power supply, Graphics card & Sound card External devices: Monitor, Keyboard, Mouse (PS2 & USB), Printer, Pen Drive I have absolutely no idea of what the routes are and how motherboards communicate, could someone give me a start here? Thanks.

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• C# - Removing event handlers - FormClosing event or Dispose() method

  - by Andy

  Suppose I have a form opened via the .ShowDialog() method. At some point I attach some event handlers to some controls on the form. e.g. // Attach radio button event handlers. this.rbLevel1.Click += new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel2.Click += new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel3.Click += new EventHandler(this.RadioButton_CheckedChanged); When the form closes, I need to remove these handlers, right? At present, I am doing this when the FormClosing event is fired. e.g. private void Foo_FormClosing(object sender, FormClosingEventArgs e) { // Detach radio button event handlers. this.rbLevel1.Click -= new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel2.Click -= new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel3.Click -= new EventHandler(this.RadioButton_CheckedChanged); } However, I have seen some examples where handlers are removed in the Dispose() method. Is there a 'best-practice' way of doing this? (Using C#, Winforms, .NET 2.0) Thanks.

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• Entity component system -> handling components that depend on one another

  - by jtedit

  I really like the idea of an entity component system and feel it has great flexibility, but have a question. How should dependent components be handled? I'm not talking about how components should communicate with other components they depend on, I have that sorted, but rather how to ensure components are present. For example, an entity cannot have a "velocity" component if it doesn't have a "position" component, in the same way it cant have an "acceleration" component if it doesn't have a "velocity" component. My first idea was every component class overrides an "onAddedToEntity(Entity ent)" function. Then in that function it checks that prerequisite components are also added to the entity, eg: struct EntCompVelocity() : public EntityComponent{ //member variables here void onAddedToEntity(Entity ent){ if(!ent.hasComponent(EntCompPosition::Id)){ ent.addComponent(new EntCompPosition()); } } } This has the nice property that if the acceleration component adds the velocity component, the velocity component will itself add the position component to the entity so dependency "trees" will sort themselves out. However my concern is if I do this components will silently be added with default values and, in the example of adding position, many entities will appear at the origin. Another idea was to simple have the "Entity.addComponent();" function return false if the component's prerequisite components aren't already on the entity, this would force you to manually add the position component and set its value before adding the velocity component. Finally I could simply not ensure a components prerequisite components are added, the "UpdatePosition" system only deals with entities with both a position and velocity component, so therefore adding a velocity component without having a position component wont be a problem (it wont cause crashes due to null pointer/etc), but it does mean entities will carry useless unused data if you add components but not their prerequisite components. Does anyone have experience with this problem and/or any of these methods to solve it? How did you solve the problem?

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• Using components in the XNA Game State Management example?

  - by Zolomon

  In the game state management example at the App Hub, they say that if you want to use components in the example you can extend the GameScreen to host other components inside itself. I'm having a very hard time trying to tie this up. I tried extending the GameScreen class by adding a public property of public List<DrawableGameCompnent> components { get; set; } and then add my components to that list when I initialize the current screen as well as looping over the components in the LoadContent, Update and Draw methods. However, this doesn't feel like the correct way to go - mainly because it doesn't work when I get to the implementation of my GameplayScreen. Any thoughts?

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• State Changes in a Component Based Architecture [closed]

  - by Maxem

  I'm currently working on a game and using the naive component based architecture thingie (Entities are a bag of components, entity.Update() calls Update on each updateable component), while the addition of new features is really simple, it makes a few things really difficult: a) multithreading / currency b) networking c) unit testing. Multithreading / Concurrency is difficult because I basically have to do poor mans concurrency (running the entity updates in separate threads while locking only stuff that crashes (like lists) and ignoring the staleness of read state (some states are already updated, others aren't)) Networking: There are no explicit state changes that I could efficiently push over the net. Unit testing: All updates may or may not conflict, so automated testing is at least awkward. I was thinking about these issues a bit and would like your input on these changes / idea: Switch from the naive cba to a cba with sub systems that work on lists of components Make all state changes explicit Combine 1 and 2 :p Example world update: statePostProcessing.Wait() // ensure that post processing has finished Apply(postProcessedState) state = new StateBag() Concurrently( () => LifeCycleSubSystem.Update(state), // populates the state bag () => MovementSubSystem.Update(state), // populates the state bag .... }) statePostProcessing = Future(() => PostProcess(state)) statePostProcessing.Start() // Tick is finished, the post processing happens in the background So basically the changes are (consistently) based on the data for the last tick; the post processing can a) generate network packages and b) fix conflicts / remove useless changes (example: entity has been destroyed - ignore movement etc.). EDIT: To clarify the granularity of the state changes: If I save these post processed state bags and apply them to an empty world, I see exactly what has happened in the game these state bags originated from - "Free" replay capability. EDIT2: I guess I should have used the term Event instead of State Change and point out that I kind of want to use the Event Sourcing pattern

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• What Every Developer Should Know About MSI Components

  - by Alois Kraus

  Hopefully nothing. But if you have to do more than simple XCopy deployment and you need to support updates, upgrades and perhaps side by side scenarios there is no way around MSI. You can create Msi files with a Visual Studio Setup project which is severely limited or you can use the Windows Installer Toolset. I cannot talk about WIX with my German colleagues because WIX has a very special meaning. It is funny to always use the long name when I talk about deployment possibilities. Alternatively you can buy commercial tools which help you to author Msi files but I am not sure how good they are. Given enough pain with existing solutions you can also learn the MSI Apis and create your own packaging solution. If I were you I would use either a commercial visual tool when you do easy deployments or use the free Windows Installer Toolset. Once you know the WIX schema you can create well formed wix xml files easily with any editor. Then you can “compile” from the wxs files your Msi package. Recently I had the “pleasure” to get my hands dirty with C++ (again) and the MSI technology. Installation is a complex topic but after several month of digging into arcane MSI issues I can safely say that there should exist an easier way to install and update files as today. I am not alone with this statement as John Robbins (creator of the cool tool Paraffin) states: “.. It's a brittle and scary API in Windows …”. To help other people struggling with installation issues I present you the advice I (and others) found useful and what will happen if you ignore this advice. What is a MSI file? A MSI file is basically a database with tables which reference each other to control how your un/installation should work. The basic idea is that you declare via these tables what you want to install and MSI controls the how to get your stuff onto or off your machine. Your “stuff” consists usually of files, registry keys, shortcuts and environment variables. Therefore the most important tables are File, Registry, Environment and Shortcut table which define what will be un/installed. The key to master MSI is that every resource (file, registry key ,…) is associated with a MSI component. The actual payload consists of compressed files in the CAB format which can either be embedded into the MSI file or reside beside the MSI file or in a subdirectory below it. To examine MSI files you need Orca a free MSI editor provided by MS. There is also another free editor called Super Orca which does support diffs between MSI and it does not lock the MSI files. But since Orca comes with a shell extension I tend to use only Orca because it is so easy to right click on a MSI file and open it with this tool. How Do I Install It? Double click it. This does work for fresh installations as well as major upgrades. Updates need to be installed via the command line via msiexec /i <msi> REINSTALL=ALL REINSTALLMODE=vomus   This tells the installer to reinstall all already installed features (new features will NOT be installed). The reinstallmode letters do force an overwrite of the old cached package in the %WINDIR%\Installer folder. All files, shortcuts and registry keys are redeployed if they are missing or need to be replaced with a newer version. When things did go really wrong and you want to overwrite everything unconditionally use REINSTALLMODE=vamus. How To Enable MSI Logs? You can download a MSI from Microsoft which installs some registry keys to enable full MSI logging. The log files can be found in your %TEMP% folder and are called MSIxxxx.log. Alternatively you can add to your msiexec command line the option msiexec …. /l*vx <LogFileName> Personally I find it rather strange that * does not mean full logging. To really get all logs I need to add v and x which is documented in the msiexec help but I still find this behavior unintuitive. What are MSI components? The whole MSI logic is bound to the concept of MSI components. Nearly every msi table has a Component column which binds an installable resource to a component. Below are the screenshots of the FeatureComponents and Component table of an example MSI. The Feature table defines basically the feature hierarchy.  To find out what belongs to a feature you need to look at the FeatureComponents table where for each feature the components are listed which will be installed when a feature is installed. The MSI components are defined in the  Component table. This table has as first column the component name and as second column the component id which is a GUID. All resources you want to install belong to a MSI component. Therefore nearly all MSI tables have a Component_ column which contains the component name. If you look e.g. a the File table you see that every file belongs to a component which is true for all other tables which install resources. The component table is the glue between all other tables which contain the resources you want to install. So far so easy. Why is MSI then so complex? Most MSI problems arise from the fact that you did violate a MSI component rule in one or the other way. When you install a feature the reference count for all components belonging to this feature will increase by one. If your component is installed by more than one feature it will get a higher refcount. When you uninstall a feature its refcount will drop by one. Interesting things happen if the component reference count reaches zero: Then all associated resources will be deleted. That looks like a reasonable thing and it is. What it makes complex are the strange component rules you have to follow. Below are some important component rules from the Tao of the Windows Installer … Rule 16: Follow Component Rules Components are a very important part of the Installer technology. They are the means whereby the Installer manages the resources that make up your application. The SDK provides the following guidelines for creating components in your package: Never create two components that install a resource under the same name and target location. If a resource must be duplicated in multiple components, change its name or target location in each component. This rule should be applied across applications, products, product versions, and companies. Two components must not have the same key path file. This is a consequence of the previous rule. The key path value points to a particular file or folder belonging to the component that the installer uses to detect the component. If two components had the same key path file, the installer would be unable to distinguish which component is installed. Two components however may share a key path folder. Do not create a version of a component that is incompatible with all previous versions of the component. This rule should be applied across applications, products, product versions, and companies. Do not create components containing resources that will need to be installed into more than one directory on the user’s system. The installer installs all of the resources in a component into the same directory. It is not possible to install some resources into subdirectories. Do not include more than one COM server per component. If a component contains a COM server, this must be the key path for the component. Do not specify more than one file per component as a target for the Start menu or a Desktop shortcut. … And these rules do not even talk about component ids, update packages and upgrades which you need to understand as well. Lets suppose you install two MSIs (MSI1 and MSI2) which have the same ComponentId but different component names. Both do install the same file. What will happen when you uninstall MSI2?   Hm the file should stay there. But the component names are different. Yes and yes. But MSI uses not use the component name as key for the refcount. Instead the ComponentId column of the Component table which contains a GUID is used as identifier under which the refcount is stored. The components Comp1 and Comp2 are identical from the MSI perspective. After the installation of both MSIs the Component with the Id {100000….} has a refcount of two. After uninstallation of one MSI there is still a refcount of one which drops to zero just as expected when we uninstall the last msi. Then the file which was the same for both MSIs is deleted. You should remember that MSI keeps a refcount across MSIs for components with the same component id. MSI does manage components not the resources you did install. The resources associated with a component are then and only then deleted when the refcount of the component reaches zero.   The dependencies between features, components and resources can be described as relations. m,k are numbers >= 1, n can be 0. Inside a MSI the following relations are valid Feature    1  –> n Components Component    1 –> m Features Component      1  –>  k Resources These relations express that one feature can install several components and features can share components between them. Every (meaningful) component will install at least one resource which means that its name (primary key to stay in database speak) does occur in some other table in the Component column as value which installs some resource. Lets make it clear with an example. We want to install with the feature MainFeature some files a registry key and a shortcut. We can then create components Comp1..3 which are referenced by the resources defined in the corresponding tables.   Feature Component Registry File Shortcuts MainFeature Comp1 RegistryKey1     MainFeature Comp2   File.txt   MainFeature Comp3   File2.txt Shortcut to File2.txt   It is illegal that the same resource is part of more than one component since this would break the refcount mechanism. Lets illustrate this:            Feature ComponentId Resource Reference Count Feature1 {1000-…} File1.txt 1 Feature2 {2000-….} File1.txt 1 The installation part works well but what happens when you uninstall Feature2? Component {20000…} gets a refcount of zero where MSI deletes all resources belonging to this component. In this case File1.txt will be deleted. But Feature1 still has another component {10000…} with a refcount of one which means that the file was deleted too early. You just have ruined your installation. To fix it you then need to click on the Repair button under Add/Remove Programs to let MSI reinstall any missing registry keys, files or shortcuts. The vigilant reader might has noticed that there is more in the Component table. Beside its name and GUID it has also an installation directory, attributes and a KeyPath. The KeyPath is a reference to a file or registry key which is used to detect if the component is already installed. This becomes important when you repair or uninstall a component. To find out if the component is already installed MSI checks if the registry key or file referenced by the KeyPath property does exist. When it does not exist it assumes that it was either already uninstalled (can lead to problems during uninstall) or that it is already installed and all is fine. Why is this detail so important? Lets put all files into one component. The KeyPath should be then one of the files of your component to check if it was installed or not. When your installation becomes corrupt because a file was deleted you cannot repair it with the Repair button under Add/Remove Programs because MSI checks the component integrity via the Resource referenced by its KeyPath. As long as you did not delete the KeyPath file MSI thinks all resources with your component are installed and never executes any repair action. You get even more trouble when you try to remove files during an upgrade (you cannot remove files during an update) from your super component which contains all files. The only way out and therefore best practice is to assign for every resource you want to install an extra component. This ensures painless updatability and repairs and you have much less effort to remove specific files during an upgrade. In effect you get this best practice relation Feature 1  –> n Components Component   1  –>  1 Resources MSI Component Rules Rule 1 – One component per resource Every resource you want to install (file, registry key, value, environment value, shortcut, directory, …) must get its own component which does never change between versions as long as the install location is the same. Penalty If you add more than one resources to a component you will break the repair capability of MSI because the KeyPath is used to check if the component needs repair. MSI ComponentId Files MSI 1.0 {1000} File1-5 MSI 2.0 {2000} File2-5 You want to remove File1 in version 2.0 of your MSI. Since you want to keep the other files you create a new component and add them there. MSI will delete all files if the component refcount of {1000} drops to zero. The files you want to keep are added to the new component {2000}. Ok that does work if your upgrade does uninstall the old MSI first. This will cause the refcount of all previously installed components to reach zero which means that all files present in version 1.0 are deleted. But there is a faster way to perform your upgrade by first installing your new MSI and then remove the old one.  If you choose this upgrade path then you will loose File1-5 after your upgrade and not only File1 as intended by your new component design.   Rule 2 – Only add, never remove resources from a component If you did follow rule 1 you will not need Rule 2. You can add in a patch more resources to one component. That is ok. But you can never remove anything from it. There are tricky ways around that but I do not want to encourage bad component design. Penalty Lets assume you have 2 MSI files which install under the same component one file   MSI1 MSI2 {1000} - ComponentId {1000} – ComponentId File1.txt File2.txt   When you install and uninstall both MSIs you will end up with an installation where either File1 or File2 will be left. Why? It seems that MSI does not store the resources associated with each component in its internal database. Instead Windows will simply query the MSI that is currently uninstalled for all resources belonging to this component. Since it will find only one file and not two it will only uninstall one file. That is the main reason why you never can remove resources from a component!   Rule 3 Never Remove A Component From an Update MSI. This is the same as if you change the GUID of a component by accident for your new update package. The resulting update package will not contain all components from the previously installed package. Penalty When you remove a component from a feature MSI will set the feature state during update to Advertised and log a warning message into its log file when you did enable MSI logging. SELMGR: ComponentId '{2DCEA1BA-3E27-E222-484C-D0D66AEA4F62}' is registered to feature 'xxxxxxx, but is not present in the Component table.  Removal of components from a feature is not supported! MSI (c) (24:44) [07:53:13:436]: SELMGR: Removal of a component from a feature is not supported Advertised means that MSI treats all components of this feature as not installed. As a consequence during uninstall nothing will be removed since it is not installed! This is not only bad because uninstall does no longer work but this feature will also not get the required patches. All other features which have followed component versioning rules for update packages will be updated but the one faulty feature will not. This results in very hard to find bugs why an update was only partially successful. Things got better with Windows Installer 4.5 but you cannot rely on that nobody will use an older installer. It is a good idea to add to your update msiexec call MSIENFORCEUPGRADECOMPONENTRULES=1 which will abort the installation if you did violate this rule.

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• Event-based server-gameloop in a server based game

  - by Chris

  I know that this site is full of questions about fixed gameloops and variable gameloops and different types of threading. But I coult find barely nothing that is related to server loops. The server has no screen to draw on. It could just run as fast as possible, but of course this makes no sense. But should it really use single "ticks" and send the updates periodically after each tick and wait for the next "tick" to update its state. Is it applicable to replace the gameloop by multilpe events? Suchs as incoming network traffic or timers? I often heared that a gameloop should be determistic, but does it really matter? For instance, when you play a shooter game against humand players and/or AI you proably would never be ably to repeat the same input twice. Is it a good idea to lose determistic behavior if it is nearly impossible to reprodruce the same input twice? So this question is more or less about whether an strictly event-based gameloop is adviseable or not and what are the pros and cons. I could imagene that an event-based gameloop could perform much faster and smoother, since you don't have bug CPU-spikes during the beginning of a new "tick". The fact that I could not find much about an event-based gameloop for servers leads me to the conclusion that inefficient or too complicated to get a real benefit from it. I'm sure if this is enough to get an idea from what I'm interessted to know, but I hope so.

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• How to implement turn-based game engine?

  - by Dvole

  Let's imagine game like Heroes of Might and Magic, or Master of Orion, or your turn-based game of choice. What is the game logic behind making next turn? Are there any materials or books to read about the topic? To be specific, let's imagine game loop: void eventsHandler(); //something that responds to input void gameLogic(); //something that decides whats going to be output on the screen void render(); //this function outputs stuff on screen All those are getting called say 60 times a second. But how turn-based enters here? I might imagine that in gameLogic() there is a function like endTurn() that happens when a player clicks that button, but how do I handle it all? Need insights.

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• Turn-based Strategy Loop

  - by Djentleman

  I'm working on a strategy game. It's turn-based and card-based (think Dominion-style), done in a client, with eventual AI in the works. I've already implemented almost all of the game logic (methods for calculations and suchlike) and I'm starting to work on the actual game loop. What is the "best" way to implement a game loop in such a game? Should I use a simple "while gameActive" loop that keeps running until gameActive is False, with sections that wait for player input? Or should it be managed through the UI with player actions determining what happens and when? Any help is appreciated. I'm doing it in Python (for now at least) to get my Python skills up a bit, although the language shouldn't matter for this question.

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• Component-based design: handling objects interaction

  - by Milo

  I'm not sure how exactly objects do things to other objects in a component based design. Say I have an Obj class. I do: Obj obj; obj.add(new Position()); obj.add(new Physics()); How could I then have another object not only move the ball but have those physics applied. I'm not looking for implementation details but rather abstractly how objects communicate. In an entity based design, you might just have: obj1.emitForceOn(obj2,5.0,0.0,0.0); Any article or explanation to get a better grasp on a component driven design and how to do basic things would be really helpful.

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• Serverside memory efficiency and threading for a turn based game

  - by SkeletorFromEterenia

  Im programming on a turn based war-game for some years now (along with the engine) and Im having quite a hard time at figuring out what the games server architecture should look like, since most game server architecture articles I found focus either on FPS oder MMOGs, which doesn't really fit since I want many matches with 1- 16 players on my server, with each match being played in turn based mode. My chief concern is memory usage, since the most basic approach of loading every game that is being played completely into RAM should be quite inefficient, so is there a suitable strategy for selecting only the needed bits and loading them? Another question I got is how to design the threading on the server, since I think using only a single thread could be a problem due to the fact that the game or part of it might have to be loaded from the database. I would be very happy if you could share your knowledge or point me to material on this topic.

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• Question about component based design: handling objects interaction

  - by Milo

  I'm not sure how exactly objects do things to other objects in a component based design. Say I have an Obj class. I do: Obj obj; obj.add(new Position()); obj.add(new Physics()); How could I then have another object not only move the ball but have those physics applied. I'm not looking for implementation details but rather abstractly how objects communicate. In an entity based design, you might just have: obj1.emitForceOn(obj2,5.0,0.0,0.0); Any article or explanation to get a better grasp on a component driven design and how to do basic things would be really helpful.

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• Text based game in XNA

  - by Sigh-AniDe

  I want to create a text based game, where the player will type up,down, left or right and the sprite will move in that direction. I created the game and at the moment the player moves with the up,left,down and right keys. I would like to change the movement of the sprite from keypresses to text commands, Ive googled a lot on creating text based games in XNA but have had no luck. Could you please help me or guide me in the right direction of how to do this in XNA. All help will greatly be appreciated. Thanks

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• Is an event loop just a for/while loop with optimized polling?

  - by Alan

  I'm trying to understand what an event loop is. Often the explanation is that in the event loop, you do something until you're notified that an event occurred. You than handle the event and continue doing what you did before. To map the above definition with an example. I have a server which 'listens' in a event loop, and when a socket connection is detected, the data from it gets read and displayed, after which the server goes to the listening it did before. However, this event happening and us getting notified 'just like that' are to much for me to handle. You can say: "It's not 'just like that' you have to register an event listener". But what's an event listener but a function which for some reason isn't returning. Is it in it's own loop, waiting to be notified when an event happens? Should the event listener also register an event listener? Where does it end? Events are a nice abstraction to work with, however just an abstraction. I believe that in the end, polling is unavoidable. Perhaps we are not doing it in our code, but the lower levels (the programming language implementation or the OS) are doing it for us. It basically comes down to the following pseudo code which is running somewhere low enough so it doesn't result in busy waiting: while(True): do stuff check if event has happened (poll) do other stuff This is my understanding of the whole idea, and i would like to hear if this is correct. I am open in accepting that the whole idea is fundamentally wrong, in which case I would like the correct explanation. Best regards

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• How Would I create alternate players (Turn base Event)

  - by Blue

  The picture above shows 2 players. Each containing 3 characters. I want to know how to make a Turn based event starting with player 1 alternating turns with player 2. And in every alternation each character gets a turn. If a character dies, the next character on the same team goes, and so on. How would I create this? Is there a tutorial? I haven't made any turn-based games so I don't know how to program these kinds of stuff.

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• ADF Business Components

  - by Arda Eralp

  ADF Business Components and JDeveloper simplify the development, delivery, and customization of business applications for the Java EE platform. With ADF Business Components, developers aren't required to write the application infrastructure code required by the typical Java EE application to: Connect to the database Retrieve data Lock database records Manage transactions   ADF Business Components addresses these tasks through its library of reusable software components and through the supporting design time facilities in JDeveloper. Most importantly, developers save time using ADF Business Components since the JDeveloper design time makes typical development tasks entirely declarative. In particular, JDeveloper supports declarative development with ADF Business Components to: Author and test business logic in components which automatically integrate with databases Reuse business logic through multiple SQL-based views of data, supporting different application tasks Access and update the views from browser, desktop, mobile, and web service clients Customize application functionality in layers without requiring modification of the delivered application The goal of ADF Business Components is to make the business services developer more productive.   ADF Business Components provides a foundation of Java classes that allow your business-tier application components to leverage the functionality provided in the following areas: Simplifying Data Access Design a data model for client displays, including only necessary data Include master-detail hierarchies of any complexity as part of the data model Implement end-user Query-by-Example data filtering without code Automatically coordinate data model changes with business services layer Automatically validate and save any changes to the database   Enforcing Business Domain Validation and Business Logic Declaratively enforce required fields, primary key uniqueness, data precision-scale, and foreign key references Easily capture and enforce both simple and complex business rules, programmatically or declaratively, with multilevel validation support Navigate relationships between business domain objects and enforce constraints related to compound components   Supporting Sophisticated UIs with Multipage Units of Work Automatically reflect changes made by business service application logic in the user interface Retrieve reference information from related tables, and automatically maintain the information when the user changes foreign-key values Simplify multistep web-based business transactions with automatic web-tier state management Handle images, video, sound, and documents without having to use code Synchronize pending data changes across multiple views of data Consistently apply prompts, tooltips, format masks, and error messages in any application Define custom metadata for any business components to support metadata-driven user interface or application functionality Add dynamic attributes at runtime to simplify per-row state management   Implementing High-Performance Service-Oriented Architecture Support highly functional web service interfaces for business integration without writing code Enforce best-practice interface-based programming style Simplify application security with automatic JAAS integration and audit maintenance "Write once, run anywhere": use the same business service as plain Java class, EJB session bean, or web service   Streamlining Application Customization Extend component functionality after delivery without modifying source code Globally substitute delivered components with extended ones without modifying the application   ADF Business Components implements the business service through the following set of cooperating components: Entity object An entity object represents a row in a database table and simplifies modifying its data by handling all data manipulation language (DML) operations for you. These are basically your 1 to 1 representation of a database table. Each table in the database will have 1 and only 1 EO. The EO contains the mapping between columns and attributes. EO's also contain the business logic and validation. These are you core data services. They are responsible for updating, inserting and deleting records. The Attributes tab displays the actual mapping between attributes and columns, the mapping has following fields: Name : contains the name of the attribute we expose in our data model. Type : defines the data type of the attribute in our application. Column : specifies the column to which we want to map the attribute with Column Type : contains the type of the column in the database   View object A view object represents a SQL query. You use the full power of the familiar SQL language to join, filter, sort, and aggregate data into exactly the shape required by the end-user task. The attributes in the View Objects are actually coming from the Entity Object. In the end the VO will generate a query but you basically build a VO by selecting which EO need to participate in the VO and which attributes of those EO you want to use. That's why you have the Entity Usage column so you can see the relation between VO and EO. In the query tab you can clearly see the query that will be generated for the VO. At this stage we don't need it and just use it for information purpose. In later stages we might use it. Application module An application module is the controller of your data layer. It is responsible for keeping hold of the transaction. It exposes the data model to the view layer. You expose the VO's through the Application Module. This is the abstraction of your data layer which you want to show to the outside word.It defines an updatable data model and top-level procedures and functions (called service methods) related to a logical unit of work related to an end-user task. While the base components handle all the common cases through built-in behavior, customization is always possible and the default behavior provided by the base components can be easily overridden or augmented. When you create EO's, a foreign key will be translated into an association in our model. It defines the type of relation and who is the master and child as well as how the visibility of the association looks like. A similar concept exists to identify relations between view objects. These are called view links. These are almost identical as association except that a view link is based upon attributes defined in the view object. It can also be based upon an association. Here's a short summary: Entity Objects: representations of tables Association: Relations between EO's. Representations of foreign keys View Objects: Logical model View Links: Relationships between view objects Application Model: interface to your application  

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• Why use event listeners over function calls?

  - by Organiccat

  I've been studying event listeners lately and I think I've finally gotten them down. Basically, they are functions that are called on another object's method. My question is, why create an event listener when calling the function will work just fine? Example, I want to call player.display_health(), and when this is fired, the method player.get_health() should be fired and stored so that display_health() has access to it. Why should I use an event listener over simply calling the function? Even if display_health() were in another object, this still doesn't appear to be a problem to me. If you have another example that fits the usage better, please let me know. Perhaps particular languages don't benefit from it as much? (Javascript, PHP, ASP?)

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• Component-based Rendering

  - by Kikaimaru

  I have component Renderer, that Draws Texture2D (or sprite) According to component-based architecture i should have only method OnUpdate, and there should be my rendering code, something like spriteBatch.Draw(Texture, Vector2.Zero, Color.White) But first I need to do spriteBatch.Begin();. Where should i call it? And how can I make sure it's called before any Renderer components OnUpdate method? (i need to do more stuff then just Begin() i also need to set right rendertarget for camera etc.)

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