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• [C#][Design] Appropriate programming design questions.

  - by Edward

  I have a few questions on good programming design. I'm going to first describe the project I'm building so you are better equipped to help me out. I am coding a Remote Assistance Tool similar to TeamViewer, Microsoft Remote Desktop, CrossLoop. It will incorporate concepts like UDP networking (using Lidgren networking library), NAT traversal (since many computers are invisible behind routers nowadays), Mirror Drivers (using DFMirage's Mirror Driver (http://www.demoforge.com/dfmirage.htm) for realtime screen grabbing on the remote computer). That being said, this program has a concept of being a client-server architecture, but I made only one program with both the functionality of client and server. That way, when the user runs my program, they can switch between giving assistance and receiving assistance without having to download a separate client or server module. I have a Windows Form that allows the user to choose between giving assistance and receiving assistance. I have another Windows Form for a file explorer module. I have another Windows Form for a chat module. I have another Windows Form form for a registry editor module. I have another Windows Form for the live control module. So I've got a Form for each module, which raises the first question: 1. Should I process module-specific commands inside the code of the respective Windows Form? Meaning, let's say I get a command with some data that enumerates the remote user's files for a specific directory. Obviously, I would have to update this on the File Explorer Windows Form and add the entries to the ListView. Should I be processing this code inside the Windows Form though? Or should I be handling this in another class (although I have to eventually pass the data to the Form to draw, of course). Or is it like a hybrid in which I process most of the data in another class and pass the final result to the Form to draw? So I've got like 5-6 forms, one for each module. The user starts up my program, enters the remote machine's ID (not IP, ID, because we are registering with an intermediary server to enable NAT traversal), their password, and connects. Now let's suppose the connection is successful. Then the user is presented with a form with all the different modules. So he can open up a File Explorer, or he can mess with the Registry Editor, or he can choose to Chat with his buddy. So now the program is sort of idle, just waiting for the user to do something. If the user opens up Live Control, then the program will be spending most of it's time receiving packets from the remote machine and drawing them to the form to provide a 'live' view. 2. Second design question. A spin off question #1. How would I pass module-specific commands to their respective Windows Forms? What I mean is, I have a class like "NetworkHandler.cs" that checks for messages from the remote machine. NetworkHandler.cs is a static class globally accessible. So let's say I get a command that enumerates the remote user's files for a specific directory. How would I "give" that command to the File Explorer Form. I was thinking of making an OnCommandReceivedEvent inside NetworkHandler, and having each form register to that event. When the NetworkHandler received a command, it would raise the event, all forms would check it to see if it was relevant, and the appropriate form would take action. Is this an appropriate/the best solution available? 3. The networking library I'm using, Lidgren, provides two options for checking networking messages. One can either poll ReadMessage() to return null or a message, or one can use an AutoResetEvent OnMessageReceived (I'm guessing this is like an event). Which one is more appropriate?

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• Limiting TCP sends with a "to-be-sent" queue and other design issues.

  - by Poni

  Hello all! This question is the result of two other questions I've asked in the last few days. I'm creating a new question because I think it's related to the "next step" in my understanding of how to control the flow of my send/receive, something I didn't get a full answer to yet. The other related questions are: http://stackoverflow.com/questions/3028376/an-iocp-documentation-interpretation-question-buffer-ownership-ambiguity http://stackoverflow.com/questions/3028998/non-blocking-tcp-buffer-issues In summary, I'm using Windows I/O Completion Ports. I have several threads that process notifications from the completion port. I believe the question is platform-independent and would have the same answer as if to do the same thing on a *nix, *BSD, Solaris system. So, I need to have my own flow control system. Fine. So I send send and send, a lot. How do I know when to start queueing the sends, as the receiver side is limited to X amount? Let's take an example (closest thing to my question): FTP protocol. I have two servers; One is on a 100Mb link and the other is on a 10Mb link. I order the 100Mb one to send to the other one (the 10Mb linked one) a 1GB file. It finishes with an average transfer rate of 1.25MB/s. How did the sender (the 100Mb linked one) knew when to hold the sending, so the slower one wouldn't be flooded? Another way to ask this: Can I get a "hold-your-sendings" notification from the remote side? Is it built-in in TCP or the so called "reliable network protocol" needs me to do so? Again, I have a loop with many sends to a remote server, and at some point, within that loop I'll have to determine if I should queue that send or I can pass it on to the transport layer (TCP). How do I do that? What would you do? Of course that when I get a completion notification from IOCP that the send was done I'll issue other pending sends, that's clear. Another design question related to this: Since I am to use a custom buffers with a send queue, and these buffers are being freed to be reused (thus not using the "delete" keyword) when a "send-done" notification has been arrived, I'll have to use a mutual exlusion on that buffer pool. Using a mutex slows things down, so I've been thinking; Why not have each thread have its own buffers pool, thus accessing it , at least when getting the required buffers for a send operation, will require no mutex, because it belongs to that thread only. The buffers pool is located at the thread local storage (TLS) level. No mutual pool implies no lock needed, implies faster operations BUT also implies more memory used by the app, because even if one thread already allocated 1000 buffers, the other one that is sending right now and need 1000 buffers to send something will need to allocated these to its own. This is a long question and I hope none got hurt (: Thank you all!

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• Decentralized synchronized secure data storage

  - by Alberich

  Introduction Hi, I am going to ask a question which seems utopic for me, but I need to know if there is a way to achieve what I need. And if not, I need to know why not. The idea Suppose I have a database structure, in MySql. I want to create some solution to allow anyone (no matter who, no matter where) to have a synchronized copy (updated clone) of this database (with its content) Well, and it is not going to be just one synchronized copy, it could (and should) be a multiple replication (supposing the basic, this means, for example, ten copies all over the world) And, the most important thing: It must be secure. By secure I mean only real-accepted transactions will be synchronized with all the others (no matter how many) database copies/clones. Note: Since it would be quite difficult to make the synchronization in real-time, I will design everything to make this feature dispensable. So it is not required. My auto-suggestion This is how I am thinking to manage it: Time identifiers and Updates checking: Every action (insert, update, delete...) will be stored as the action instruction itself, associated to the time identifier. [I think better than a DATETIME field, it'll be an INT one, with the number of miliseconds passed from 1st january 2013 on, for example]. So each copy is going to ask to the "neighbour copy" for new actions done since last update, and execute them after checking they are allowed. Problem 1: the "neighbour copy" could be outdated too. Solution 1: do not ask just one neighbour, create a random list with some of the copies/clones and ask them for news (I could avoid the list and ask ALL the clones for updates, but this will be inefficient if clones number ascends too much). Problem 2: Real-time global synchronization is not active. What if... Someone at CLONE_ENTERPRISING inserts a row into TABLE. ... this row goes to every clone ... Someone at CLONE_FIXEMALL deletes this row. ... and at the same time, somewhere in an outdated clone ... Someone at CLONE_DROPOUT edits this row (now inexistent at the other clones) Solution 2: easy stuff, force a GLOBAL synchronization before doing any new "depending-on-third-data action" (edit, for example). This global synch. will be unnecessary when making an INSERT, for instance. Note: Well, someone could have some fun, and make the same insert in two clones... since they're not getting updated in real-time, this row will exist twice. But, it's the same as when we have one single database, in some needed cases we check if there is an existing same-row before doing the final action. Not a problem. Problem 3: It is possible to edit the code and do not filter actions, so someone could spread instructions to delete everything, or just make some trolling activity. This is not a problem, since good clones will always be somewhere. Those who got bad won't interest anymore. I really appreciate if you read. I know this is not the perfect solution, it has possibly hundred of holes, but it is my basic start. I will now appreciate anything you can teach me now. Thanks a lot. PS.: It could be that all this I am trying already exists and has its own name. Sorry for asking then (I'd anyway thank this name, if it exists)

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• Do you have suggestions for these assembly mnemonics?

  - by Noctis Skytower

  Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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• Generating cache file for Twitter rss feed

  - by Kerri

  I'm working on a site with a simple php-generated twitter box with user timeline tweets pulled from the user_timeline rss feed, and cached to a local file to cut down on loads, and as backup for when twitter goes down. I based the caching on this: http://snipplr.com/view/8156/twitter-cache/. It all seemed to be working well yesterday, but today I discovered the cache file was blank. Deleting it then loading again generated a fresh file. The code I'm using is below. I've edited it to try to get it to work with what I was already using to display the feed and probably messed something crucial up. The changes I made are the following (and I strongly believe that any of these could be the cause): - Revised the time difference code (the linked example seemed to use a custom function that wasn't included in the code) Removed the "serialize" function from the "fwrites". This is purely because I couldn't figure out how to unserialize once I loaded it in the display code. I truthfully don't understand the role that serialize plays or how it works, so I'm sure I should have kept it in. If that's the case I just need to understand where/how to deserialize in the second part of the code so that it can be parsed. Removed the $rss variable in favor of just loading up the cache file in my original tweet display code. So, here are the relevant parts of the code I used: <?php $feedURL = "http://twitter.com/statuses/user_timeline/#######.rss"; // START CACHING $cache_file = dirname(__FILE__).'/cache/twitter_cache.rss'; // Start with the cache if(file_exists($cache_file)){ $mtime = (strtotime("now") - filemtime($cache_file)); if($mtime > 600) { $cache_rss = file_get_contents('http://twitter.com/statuses/user_timeline/75168146.rss'); $cache_static = fopen($cache_file, 'wb'); fwrite($cache_static, $cache_rss); fclose($cache_static); } echo "<!-- twitter cache generated ".date('Y-m-d h:i:s', filemtime($cache_file))." -->"; } else { $cache_rss = file_get_contents('http://twitter.com/statuses/user_timeline/#######.rss'); $cache_static = fopen($cache_file, 'wb'); fwrite($cache_static, $cache_rss); fclose($cache_static); } //END CACHING //START DISPLAY $doc = new DOMDocument(); $doc->load($cache_file); $arrFeeds = array(); foreach ($doc->getElementsByTagName('item') as $node) { $itemRSS = array ( 'title' => $node->getElementsByTagName('title')->item(0)->nodeValue, 'date' => $node->getElementsByTagName('pubDate')->item(0)->nodeValue ); array_push($arrFeeds, $itemRSS); } // the rest of the formatting and display code.... } ?> ETA 6/17 Nobody can help…? I'm thinking it has something to do with writing a blank cache file over a good one when twitter is down, because otherwise I imagine that this should be happening every ten minutes when the cache file is overwritten again, but it doesn't happen that frequently. I made the following change to the part where it checks how old the file is to overwrite it: $cache_rss = file_get_contents('http://twitter.com/statuses/user_timeline/75168146.rss'); if($mtime > 600 && $cache_rss != ''){ $cache_static = fopen($cache_file, 'wb'); fwrite($cache_static, $cache_rss); fclose($cache_static); } …so now, it will only write the file if it's over ten minutes old and there's actual content retrieved from the rss page. Do you think this will work?

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• ASP.NET - Call required field validator before AJAX modalpopup, client side

  - by odinel

  I have an ASP.NET/C# application. The user fills out a form with required fields, then clicks a submit button. An AJAX popup message is then displayed, and if they confirm, their information is posted back to the server. The problem is that the AJAX popup is fired BEFORE the req validator. I need to interrupt this and run the req validator, and then if successful show the popup. I know the req validator is working, because if you cancel the popup message, the req text is shown next to the fields. Textbox and AJAX control code is here: <table> <tr> <td>Name</td> <td> <asp:TextBox ID="txtName" runat="server" CssClass="textBox" AutoPostBack="true"></asp:TextBox> <asp:RequiredFieldValidator ID="reqName" runat="server" Text="*" ControlToValidate="txtName" ValidationGroup="trade" ForeColor="White"></asp:RequiredFieldValidator> </td> </tr> <tr> <td>Address</td> <td> <asp:TextBox ID="txtAdd1" runat="server" CssClass="textBox"></asp:TextBox> <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" Text="*" ControlToValidate="txtAdd1" ValidationGroup="trade" ForeColor="White"></asp:RequiredFieldValidator> </td> </tr> <tr> <td></td> <td> <asp:Button ID="btnSubmitEnquiry" runat="server" CssClass="buttonText" Text="Submit Enquiry" ValidationGroup="trade" /> </td> </tr> </table> <ajax:ModalPopupExtender ID="ModalPopupExtender1" runat="server" okcontrolid="lnkCancel" targetcontrolid="btnSubmitEnquiry" popupcontrolid="pnlConfirm" popupdraghandlecontrolid="PopupHeader" drag="true" ></ajax:ModalPopupExtender> <asp:Button Text="targetbutton" ID="btnConfTgt" runat="server" Style="display: none" /> <asp:Panel ID="pnlConfirm" style="display:none" runat="server"> <div class="PopupContainer"> <div class="PopupBody"> <br /> <div align="center"> <asp:label ID="Label1" runat="server" CssClass="lblConfirmpopup"> Message goes here </asp:label> </div> <br /><br /><br /> <div align="center"> <asp:LinkButton ID="lnkCancel" runat="server" visible="true" Text="Cancel" CommandName="Update" BorderColor="#FFFFFF" BackColor="#000000" BorderWidth="3" BorderStyle="Double" ForeColor="White" Font-Size="13pt" Font-Underline="False"></asp:LinkButton> <asp:LinkButton ID="lnkConfirm" runat="server" visible="true" Text="Submit Enquiry" CommandName="Update" BorderColor="#FFFFFF" BackColor="#000000" BorderWidth="3" BorderStyle="Double" ForeColor="White" Font-Size="13pt" Font-Underline="False" OnClick="btnSubmitEnquiry_Click"></asp:LinkButton> </div> </div> </div> </asp:Panel> I've tried coding the first submit button to call the client-side req validator method, but no joy; it still shows the popup before the req validator. If there's no simple solution, I was thinking of perhaps an 'outside the box' solution, maybe hiding the initial Submit button after the req validation has passed, then showing an additional button with the popup control attached to it. Not sure how I'd be able to achieve this though. Thanks

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• Vertical text inside table headers using a JavaScript-based SVG library

  - by Oleg

  I use jqGrid with many columns containing boolean information, which are displayed as checkboxes inside the table (see http://www.ok-soft-gmbh.com/VerticalHeaders/TestFixedO.htm as an example). To display information more compactly I use vertical column headers. It works very well and works in jqGrid in all browsers (see my discussion with Tony Tomov in jqGrid forum http://www.trirand.com/blog/?page_id=393/feature-request/headers-with-vertical-orientation/), but in IE vertical text is blurred and doesn't look nice enough (open the link above in IE and you will see exactly what I mean). I was asked from users why the text displayed so strangely. So I'm thinking of using a JavaScript-based SVG library like SVG Web ( http://code.google.com/p/svgweb/ ) or Raphaël ( http://raphaeljs.com/ ). SVG is very powerful and it is difficult to find a good example. I need only to display vertical text (-90 grad, from the bottom up) and use if possible without working in mode of absolute positioning. So one more time my question: I need to have a possibility to display vertical text (-90 grad rotation) inside <td> elements of a table header. I want to use a JavaScript-based SVG library like SVG Web or Raphaël. The solution must support IE6. Does anybody have a good reference example which could help me do this? If somebody posts a whole solution of the problem I would be happy. To be exact here is my current solution: I define .rotate { -webkit-transform: rotate(-90deg); /* Safari 3.1+, Chrome */ -moz-transform: rotate(-90deg); /* Firefox 3.5+ */ -o-transform: rotate(-90deg); /* Opera starting with 10.50 */ /* Internet Explorer: */ filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=3); /* IE6, IE7 */ -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=3)" /* IE8 */; } define RotateCheckboxColumnHeaders function var RotateCheckboxColumnHeaders = function (grid, headerHeight) { // we use grid as context (if one have more as one table on tnhe page) var trHead = $("thead:first tr", grid.hdiv); var cm = grid.getGridParam("colModel"); $("thead:first tr th").height(headerHeight); headerHeight = $("thead:first tr th").height(); for (var iCol = 0; iCol < cm.length; iCol++) { var cmi = cm[iCol]; if (cmi.formatter === 'checkbox') { // we must set width of column header div BEFOR adding class "rotate" to // prevent text cutting based on the current column width var headDiv = $("th:eq(" + iCol + ") div", trHead); headDiv.width(headerHeight).addClass("rotate"); if (!$.browser.msie) { if ($.browser.mozilla) { headDiv.css("left", (cmi.width - headerHeight) / 2 + 3).css("bottom", 7); } else { headDiv.css("left", (cmi.width - headerHeight) / 2); } } else { var ieVer = jQuery.browser.version.substr(0, 3); // Internet Explorer if (ieVer !== "6.0" && ieVer !== "7.0") { headDiv.css("left", cmi.width / 2 - 4).css("bottom", headerHeight / 2); $("span", headDiv).css("left", 0); } else { headDiv.css("left", 3); } } } } }; And include a call like RotateCheckboxColumnHeaders(grid, 110); after creating jqGrid.

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• Data munging and data import scripting

  - by morpheous

  I need to write some scripts to carry out some tasks on my server (running Ubuntu server 8.04 TLS). The tasks are to be run periodically, so I will be running the scripts as cron jobs. I have divided the tasks into "group A" and "group B" - because (in my mind at least), they are a bit different. Task Group A import data from a file and possibly reformat it - by reformatting, I mean doing things like santizing the data, possibly normalizing it and or running calculations on 'columns' of the data Import the munged data into a database. For now, I am mostly using mySQL for the vast majority of imports - although some files will be imported into a sqlLite database. Note: The files will be mostly text files, although some of the files are in a binary format (my own proprietary format, written by a C++ application I developed). Task Group B Extract data from the database Perform calculations on the data and either insert or update tables in the database. My coding experience is is primarily as a C/C++ developer, although I have been using PHP as well for the last 2 years or so. I am from a windows background so I am still finding my feet in the linux environment. My question is this - I need to write scripts to perform the tasks I described above. Although I suppose I could write a few C++ applications to be used in the shell scripts, I think it may be better to write them in a scripting language (maybe this is a flawed assumption?). My thinking is that it would be easier to modify thins in a script - no need to rebuild etc for changes to functionality. Additionally, C++ data munging in C++ tends to involve more lines of code than "natural" scripting languages such as Perl, Python etc. Assuming that the majority of people on here agree that scripting is the way to go, herein lies my dilema. Which scripting language to use to perform the tasks above (giving my background). My gut instinct tells me that Perl (shudder) would be the most obvious choice for performing all of the above tasks. BUT (and that is a big BUT). The mere mention of Perl makes my toes curl, as I had a very, very bag experience with it a while back. The syntax seems quite unnatural to me - despite how many times I have tried to learn it - so if possible, I would really like to give it a miss. PHP (which I already know), also am not sure is a good candidate for scripting on the CLI (I have not seen many examples on how to do this etc - so I may be wrong). The last thing I must mention is that IF I have to learn a new language in order to do this, I cannot afford (time constraint) to spend more than a day, in learning the key commands/features required in order to do this (I can always learn the details of the language later, once I have actually deployed the scripts). So, which scripting language would you recommend (PHP, Python, Perl, [insert your favorite here]) - and most importantly WHY?. Or, should I just stick to writing little C++ applications that I call in a shell script?. Lastly, if you have suggested a scripting language, can you please show with a FEW lines (Perl mongers - I'm looking in your direction [nothing to cryptic!] ;) ) how I can use the language you suggested to do what I want to do. Hopefully, the lines you present will convince me that it can be done easily and elegantly in the language you suggested.

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• PostgreSQL triggers and passing parameters

  - by iandouglas

  This is a multi-part question. I have a table similar to this: CREATE TABLE sales_data ( Company character(50), Contract character(50), top_revenue_sum integer, top_revenue_sales integer, last_sale timestamp) ; I'd like to create a trigger for new inserts into this table, something like this: CREATE OR REPLACE FUNCTION add_contract() RETURNS VOID DECLARE myCompany character(50), myContract character(50), BEGIN myCompany = TG_ARGV[0]; myContract = TG_ARGV[1]; IF (TG_OP = 'INSERT') THEN EXECUTE 'CREATE TABLE salesdata_' || $myCompany || '_' || $myContract || ' ( sale_amount integer, updated TIMESTAMP not null, some_data varchar(32), country varchar(2) ) ;' EXECUTE 'CREATE TRIGGER update_sales_data BEFORE INSERT OR DELETE ON salesdata_' || $myCompany || '_' || $myContract || ' FOR EACH ROW EXECUTE update_sales_data( ' || $myCompany || ',' || $myContract || ', revenue);' ; END IF; END; $add_contract$ LANGUAGE plpgsql; CREATE TRIGGER add_contract AFTER INSERT ON sales_data FOR EACH ROW EXECUTE add_contract() ; Basically, every time I insert a new row into sales_data, I want to generate a new table where the name of the table will be defined as something like "salesdata_Company_Contract" So my first question is how can I pass the Company and Contract data to the trigger so it can be passed to the add_contract() stored procedure? From my stored procedure, you'll see that I also want to update the original sales_data table whenever new data is inserted into the salesdata_Company_Contract table. This trigger will do something like this: CREATE OR REPLACE FUNCTION update_sales_data() RETURNS trigger as $update_sales_data$ DECLARE myCompany character(50) NOT NULL, myContract character(50) NOT NULL, myRevenue integer NOT NULL BEGIN myCompany = TG_ARGV[0] ; myContract = TG_ARGV[1] ; myRevenue = TG_ARGV[2] ; IF (TG_OP = 'INSERT') THEN UPDATE sales_data SET top_revenue_sales = top_revenue_sales + 1, top_revenue_sum = top_revenue_sum + $myRevenue, updated = now() WHERE Company = $myCompany AND Contract = $myContract ; ELSIF (TG_OP = 'DELETE') THEN UPDATE sales_data SET top_revenue_sales = top_revenue_sales - 1, top_revenue_sum = top_revenue_sum - $myRevenue, updated = now() WHERE Company = $myCompany AND Contract = $myContract ; END IF; END; $update_sales_data$ LANGUAGE plpgsql; This will, of course, require that I pass several parameters around within these stored procedures and triggers, and I'm not sure (a) if this is even possible, or (b) practical, or (c) best practice and we should just put this logic into our other software instead of asking the database to do this work for us. To keep our table sizes down, as we'll have hundreds of thousands of transactions per day, we've decided to partition our data using the Company and Contract strings as part of the table names themselves so they're all very small in size; file IO for us is faster and we felt we'd get better performance. Thanks for any thoughts or direction. My thinking, now that I've written all of this out, is that maybe we need to write stored procedures where we pass our insert data as parameters, and call that from our other software, and have the stored procedure do the insert into "sales_data" then create the other table. Then, have a second stored procedure to insert new data into the salesdata_Company_Contract tables, where the table name is passed to the stored proc as a parameter, and again have that stored proc do the insert, then update the main sales_data table afterward. What approach would you take?

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• iPhone game and reading plist file and looping through multidimensional array.

  - by Fulvio

  I have a question regarding an iPhone game I'm developing. At the moment, below is the code I'm using to currently I loop through my multidimensional array and position bricks accordingly on my scene. Instead of having multiple two dimensional arrays within my code as per the following (gameLevel1). Ideally, I'd like to read from a .plist file within my project and loop through the values in that instead. Please take into account that I'd like to have more than one level within my game (possibly 20) so my .plist file would have to have some sort of separator line item to determine what level I want to render. I was then thinking of having some sort of method that I call and that method would take the level number I'm interested in rendering. e.g. Method? +(void)renderLevel:(NSString levelNumber); e.g. .plist file? #LEVEL_ONE# 0,0,0,0,0,0,0,0,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,0,0,0,0,0,0,0,0 #LEVEL_TWO# 1,0,0,0,0,0,0,0,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 0,1,1,1,1,1,1,1,0 1,1,1,1,1,1,1,1,1 0,1,1,1,1,1,1,1,0 1,1,1,1,1,1,1,1,1 0,1,1,1,1,1,1,1,0 1,1,1,1,1,1,1,1,1 0,1,1,1,1,1,1,1,0 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,0,0,0,0,0,0,0,1 Code that I'm currently using: int gameLevel[17][9] = { { 0,0,0,0,0,0,0,0,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,0,0,0,0,0,0,0,0 } }; for (int row=0; row < 17; row++) { for (int col=0; col < 17; col++) { thisBrickValue = gameLevel[row][col]; xOffset = 35 * floor(col); yOffset = 22 * floor(row); switch (thisBrickValue) { case 0: brick = [[CCSprite spriteWithFile:@"block1.png"] autorelease]; break; case 1: brick = [[CCSprite spriteWithFile:@"block0.png"] autorelease]; break; } brick.position = ccp(xOffset, yOffset); [self addChild:brick]; } }

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• How to cope with developing against a poor 3rd party API/application?

  - by wsanville

  I'm a web developer, and my organization has recently started to use a proprietary ASP.NET CMS for our web sites. I was excited to get started using the CMS, thinking it would bring a lot of value to our end users and be fun to work with, since my skills are a good match for the types of projects we're using it for. That was about a year ago. Since then, we've ran into all kinds of issues, from blatant bugs in the product, to nasty edge cases in the APIs, to extremely poor documentation for developers. On about a weekly basis, we are forced to pursue workarounds and rewrite some of the out of the box functionality, and even find some of the basic features unusable. In many cases, since this is a closed source application (and obfuscated of course), there's nothing we can do as developers to solve these issues. So my question is, how does one attempt to develop a good application in such a scenario? The application mostly works when using the the exact out of the box behavior, or using one of the company's starter sites. However, my attempts to use the underlying APIs to implement slightly different, yet reasonable behavior has proved to be extremely time consuming (not to mention just as buggy), given the lack of good information about the APIs. I've given this a lot of thought, and my conflicting viewpoints are the following: Strongly advise against any customization to the CMS, as development time will rise exponentially, or even have an extremely high chance of failing. While this is accurate, I do not want to give the impression that I am not willing to code my own solutions to problems and take the initiative to implement something difficult or complex. I don't want to be perceived as someone who is not motivated, lazy, or not knowledgeable to do anything complex, because this is simply not the case. I love coding my own solutions, trying new/difficult things, I just dislike the vendor app we're using. Continue on the path I'm on now, which is hacking my way past all issues I encounter and try my best to deliver an application that meets the needs and specs exactly. My goals are to make it as seamless and easy to use as possible to the end user, even when integrating the CMS with our other applications internally. The problem I'm finding with this approach is it is very time consuming. I open support cases with the vendor on a regular basis to solve issues and to gain knowledge of their APIs, but this is extremely time consuming, and in some cases it leads to dead ends. I post on the vendors forums on a regular basis but have become frustrated as most of my posts get 0 replies. So, what would you, a reasonable developer, do in this case? How can I make the best of the situation? And just for fun, here are some of the code smells and anti-patterns I've dealt with using the product (aside from their own code blatantly failing): Use of StringBuilder to concatenate a giant string that is hard coded and does not change. They use it to concatenate their Javascript and write it out into the body tags of their pages. Methods that accept object or Microsoft.VisualBasic.Collection as the parameters. In the case of the VB Collection, the data is not a list of any kind, it's used instead of making a class. Methods that return a Hashtable of VB Collections Method names of the form MethodName_v45, MethodName_v20, etc... Multiple classes with the same name in different namespaces with different functionality/behavior. Intellisense that reads "Note: this parameter is non functional" Complete lack of coding standards, API is filled with magic numbers and magic strings. Properties with a getter of type object that accepts totally different things, like enum or strings, and throw exceptions at runtime when you pass in something not supported. And much, much, more...

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• Where are the function address literals in c++?

  - by academicRobot

  First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). <UPDATE> After some reading with help from answer by Chris Dodd, what I'm looking for is literal function addresses as template parameters. Chris' answer indicates how to do this for standard functions, but how can the addresses of member functions be used as template parameters? Since the standard prohibits non-static member function addresses as template parameters (c++03 14.3.2.3), I suspect the work around is quite complicated. Any ideas for a workaround? Below the original form of the question is left as is for context. </UPDATE> The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one. Edit The intent of this question is not to implement delegates, rather to identify a pattern that will embed a conventional function call, (in immediate mode) directly into third party code, possibly a template.

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• Database Table Schema and Aggregate Roots

  - by bretddog

  Hi, Applicaiton is single user, 1-tier(1 pc), database SqlCE. DataService layer will be (I think) : Repository returning domain objects and quering database with LinqToSql (dbml). There are obviously a lot more columns, this is simplified view. http://img573.imageshack.us/img573/3612/ss20110115171817w.png This is my first attempt of creating a 2 tables database. I think the table schema makes sense, but I need some reassurance or critics. Because the table relations looks quite scary to be honest. I'm hoping you could; Look at the table schema and respond if there are clear signs of troubles or errors that you spot right away.. And if you have time, Look at Program Summary/Questions, and see if the table layout makes makes sense to those points. Please be brutal, I will try to defend :) Program summary: a) A set of categories, each having a set of strategies (1:m) b) Each day a number of items will be produced. And each strategy MAY reference it. (So there can be 50 items, and a strategy may reference 23 of them) c) An item can be referenced by more than one strategy. So I think it's an m:m relation. d) Status values will be logged at fixed time-fractions through the day, for: - .... each Strategy.....each StrategyItem....each item e) An action on an item may be executed by a strategy that reference it. - This is logged as ItemAction (Could have called it StrategyItemAction) User Requsts b) - e) described the main activity mode of the program. To work with only today's DayLog , for each category. 2nd priority activity is retrieval of history, which typically will be From all categories, from day x to day y; Get all StrategyDailyLog. Questions First, does the overall layout look sound? I'm worried to see that there are so many relationships in all directions, connecting everything. Is this normal, or does it look like trouble? StrategyItem is made to represent an m:m relationship. Is it correct as I noted 1:m / 1:1 (marked red) ? StrategyItemTimeLog and ItemTimeLog; Logs values that both need to be retrieved together, when retreiving a StrategyItem. Reason I separated is that the first one is strategy-specific, and several strategies can reference same item. So I thought not to duplicate those values that are not dependent no strategy, but only on the item. Hence I also dragged out the LogTime, as it seems to be the only parameter to unite the logs. But this all looks quite disturbing with those 3 tables. Does it make sense at all? Or you have suggestion? Pink circles shows my vague attempt of Aggregate Root Paths. I've been thinking in terms of "what entity is responsible for delete". Though I'm unsure about the actual root. I think it's Category. Does it make sense related to User Requests described above?

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• Replace conditional with polymorphism refactoring or similar?

  - by Anders Svensson

  Hi, I have tried to ask a variant of this question before. I got some helpful answers, but still nothing that felt quite right to me. It seems to me this shouldn't really be that hard a nut to crack, but I'm not able to find an elegant simple solution. (Here's my previous post, but please try to look at the problem stated here as procedural code first so as not to be influenced by the earlier explanation which seemed to lead to very complicated solutions: http://stackoverflow.com/questions/2772858/design-pattern-for-cost-calculator-app ) Basically, the problem is to create a calculator for hours needed for projects that can contain a number of services. In this case "writing" and "analysis". The hours are calculated differently for the different services: writing is calculated by multiplying a "per product" hour rate with the number of products, and the more products are included in the project, the lower the hour rate is, but the total number of hours is accumulated progressively (i.e. for a medium-sized project you take both the small range pricing and then add the medium range pricing up to the number of actual products). Whereas for analysis it's much simpler, it is just a bulk rate for each size range. How would you be able to refactor this into an elegant and preferably simple object-oriented version (please note that I would never write it like this in a purely procedural manner, this is just to show the problem in another way succinctly). I have been thinking in terms of factory, strategy and decorator patterns, but can't get any to work well. (I read Head First Design Patterns a while back, and both the decorator and factory patterns described have some similarities to this problem, but I have trouble seeing them as good solutions as stated there. The decorator example seems very complicated for just adding condiments, but maybe it could work better here, I don't know. And the factory pattern example with the pizza factory...well it just seems to create such a ridiculous explosion of classes, at least in their example. I have found good use for factory patterns before, but I can't see how I could use it here without getting a really complicated set of classes) The main goal would be to only have to change in one place (loose coupling etc) if I were to add a new parameter (say another size, like XSMALL, and/or another service, like "Administration"). Here's the procedural code example: public class Conditional { private int _numberOfManuals; private string _serviceType; private const int SMALL = 2; private const int MEDIUM = 8; public int GetHours() { if (_numberOfManuals <= SMALL) { if (_serviceType == "writing") return 30 * _numberOfManuals; if (_serviceType == "analysis") return 10; } else if (_numberOfManuals <= MEDIUM) { if (_serviceType == "writing") return (SMALL * 30) + (20 * _numberOfManuals - SMALL); if (_serviceType == "analysis") return 20; } else //i.e. LARGE { if (_serviceType == "writing") return (SMALL * 30) + (20 * (MEDIUM - SMALL)) + (10 * _numberOfManuals - MEDIUM); if (_serviceType == "analysis") return 30; } return 0; //Just a default fallback for this contrived example } } All replies are appreciated! I hope someone has a really elegant solution to this problem that I actually thought from the beginning would be really simple... Regards, Anders

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• Defend PHP; convince me it isn't horrible

  - by Jason L

  I made a tongue-in-cheek comment in another question thread calling PHP a terrible language and it got down-voted like crazy. Apparently there are lots of people here who love PHP. So I'm genuinely curious. What am I missing? What makes PHP a good language? Here are my reasons for disliking it: PHP has inconsistent naming of built-in and library functions. Predictable naming patterns are important in any design. PHP has inconsistent parameter ordering of built-in functions, eg array_map vs. array_filter which is annoying in the simple cases and raises all sorts of unexpected behaviour or worse. The PHP developers constantly deprecate built-in functions and lower-level functionality. A good example is when they deprecated pass-by-reference for functions. This created a nightmare for anyone doing, say, function callbacks. A lack of consideration in redesign. The above deprecation eliminated the ability to, in many cases, provide default keyword values for functions. They fixed this in PHP 5, but they deprecated the pass-by-reference in PHP 4! Poor execution of name spaces (formerly no name spaces at all). Now that name spaces exist, what do we use as the dereference character? Backslash! The character used universally for escaping, even in PHP! Overly-broad implicit type conversion leads to bugs. I have no problem with implicit conversions of, say, float to integer or back again. But PHP (last I checked) will happily attempt to magically convert an array to an integer. Poor recursion performance. Recursion is a fundamentally important tool for writing in any language; it can make complex algorithms far simpler. Poor support is inexcusable. Functions are case insensitive. I have no idea what they were thinking on this one. A programming language is a way to specify behavior to both a computer and a reader of the code without ambiguity. Case insensitivity introduces much ambiguity. PHP encourages (practically requires) a coupling of processing with presentation. Yes, you can write PHP that doesn't do so, but it's actually easier to write code in the incorrect (from a sound design perspective) manner. PHP performance is abysmal without caching. Does anyone sell a commercial caching product for PHP? Oh, look, the designers of PHP do. Worst of all, PHP convinces people that designing web applications is easy. And it does indeed make much of the effort involved much easier. But the fact is, designing a web application that is both secure and efficient is a very difficult task. By convincing so many to take up programming, PHP has taught an entire subgroup of programmers bad habits and bad design. It's given them access to capabilities that they lack the understanding to use safely. This has led to PHP's reputation as being insecure. (However, I will readily admit that PHP is no more or less secure than any other web programming language.) What is it that I'm missing about PHP? I'm seeing an organically-grown, poorly-managed mess of a language that's spawning poor programmers. So convince me otherwise!

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• MVC Datatables Dialog Not staying where dialog opens

  - by Anthoney Hanks

  I have created a view that displays a datatable with a clickable link that opens a jQuery UI dialog box. The users wanted a search options (8 dropdowns to narrow the search) at top of page, followed by the datatable with the 100 viewable records. If I scroll down the datatable to the bottom viewable record, click the link to open the dialog box. The dialog opens relative to the link clicked, but the focus go back to the top of the page which causes the user to have scroll back down to the dialog box. Ok, I thought I would just set the focus to the dialog box. BUt it is being ignored which make me think that this is something within the MVC realm. I even tried to wrap the focus inside a ready function thinking it would be one of the last things process. When I define the dailog, it is pretty basic. I even tried to set the position attribute, but it did not change the problem. Has someone had this problem and can send me in the right direction? View building the datatable: <table id="navDatatables"> <tbody> @foreach (var detailsVM in Model.DetailsVMs) { <tr> <td class="standardTable"> <a href="#" onclick="return PVE_UseConfig.Options(@detailsVM.ConfigVersionId, @Model.UseConfigModeId);" class="smallLink">Options</a> </td> <td class="standardTable"> <a href="@Url.Content(@detailsVM.ViewerUrl)" target="_blank">@detailsVM.ConfigName</a> </td> <td class="standardTable">@detailsVM.ConfigType</td> <td class="standardTable">@detailsVM.ConfigVersionState</td> <td class="standardTable">@detailsVM.Organization</td> <td class="standardTable">@detailsVM.ProcessSet</td> <td class="standardTable">@detailsVM.ConfigVersionCaption</td> <td class="standardTable">@detailsVM.ConfigId</td> <td class="standardTable">@detailsVM.ConfigVersionId</td> <td class="standardTable">@detailsVM.ConfigOwnerName</td> <td class="standardTable">@detailsVM.ConfigVersionLastModified</td> </tr> } </tbody> </table> Dialog box code: Options: function (configVersionId, useConfigModeId) { var output = '#modalDialog1'; var postData = { configVersionId: configVersionId, useConfigModeId: useConfigModeId }; $('#modalDialog1').dialog("destroy"); $.ajax({ url: PVE_RootUrl + 'UseConfig/Options', type: 'POST', async: false, data: postData, success: function (result) { $(output).html(result); }, error: function (jqXHR, textStatus, errorThrown) { var text = jqXHR.responseText; var from = text.search("<body>") + 6; var to = text.search("</body>") - 7; $(output).html(text.substring(from, to)); } }); $(output).dialog({ title: "Configuration Options", modal: true, height: 550, width: 600, resizable: false, draggable: false }); },

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• BFS Shortest Path: Edge weight either 1 or 2

  - by Hackster

  I am trying to implement a shortest path algorithm using BFS. That is I am trying to find the shortest path from a specified vertex to every other vertex. However, its a special case where all edge weights are either 1 or 2. I know it could be done with Dijkstra's algorithm but I must use Breadth First Search. So far I have a working version of BFS that searches first for a vertex connected with an edge of weight 1. If it cannot find it, then returns a vertex connected with an edge of weight 2. After thinking about it, this is not the correct way to find the shortest path. The problem is I cannot think of any reasoning why BFS would work with weights 1 or 2, as opposed to any weight. Here is the code: public void addEdge(int start, int end, int weight) { adjMat[start][end] = 1; adjMat[end][start] = 1; edge_weight[start][end] = weight; edge_weight[end][start] = weight; } // ------------------------------------------------------------- public void bfs() // breadth-first search { // begin at vertex 0 vertexList[0].wasVisited = true; // mark it displayVertex(0); // display it theQueue.insert(0); // insert at tail int v2; while( !theQueue.isEmpty() ) // until queue empty, { int v1 = theQueue.remove(); // remove vertex at head // until it has no unvisited neighbors while( (v2=getAdjUnvisitedVertex(v1)) != -1 ){// get one, vertexList[v2].wasVisited = true; // mark it displayVertex(v2); // display it theQueue.insert(v2); // insert it } } // end while(queue not empty) // queue is empty, so we're done for(int j=0; j<nVerts; j++) // reset flags vertexList[j].wasVisited = false; } // end bfs() // ------------------------------------------------------------- // returns an unvisited vertex adj to v -- ****WITH WEIGHT 1**** public int getAdjUnvisitedVertex(int v) { for (int j = 0; j < nVerts; j++) if (adjMat[v][j] == 1 && vertexList[j].wasVisited == false && edge_weight[v][j] == 1){ //System.out.println("Vertex found with 1:"+ vertexList[j].label); return j; } for (int k = 0; k < nVerts; k++) if (adjMat[v][k] == 1 && vertexList[k].wasVisited == false && edge_weight[v][k] == 2){ //System.out.println("Vertex found with 2:"+vertexList[k].label); return k; } return -1; } // end getAdjUnvisitedVertex() // ------------------------------------------------------------- } //////////////////////////////////////////////////////////////// public class BFS{ public static void main(String[] args) { Graph theGraph = new Graph(); theGraph.addVertex('A'); // 0 (start for bfs) theGraph.addVertex('B'); // 1 theGraph.addVertex('C'); // 2 theGraph.addEdge(0, 1,2); // AB theGraph.addEdge(1, 2,1); // BC theGraph.addEdge(2, 0,1); // AD System.out.print("Visits: "); theGraph.bfs(); // breadth-first search System.out.println(); } // end main() } The problem then is, that I don't know why BFS can work for the shortest path problem with edges of weight 1 or 2 as opposed to any edges of any weight. Any help is appreciated. Thanks!

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• Game logic dynamically extendable architecture implementation patterns

  - by Vlad

  When coding games there are a lot of cases when you need to inject your logic into existing class dynamically and without making unnecessary dependencies. For an example I have a Rabbit which can be affected by freeze ability so it can't jump. It could be implemented like this: class Rabbit { public bool CanJump { get; set; } void Jump() { if (!CanJump) return; ... } } But If I have more than one ability that can prevent it from jumping? I can't just set one property because some circumstances can be activated simultanously. Another solution? class Rabbit { public bool Frozen { get; set; } public bool InWater { get; set; } bool CanJump { get { return !Frozen && !InWater; } } } Bad. The Rabbit class can't know all the circumstances it can run into. Who knows what else will game designer want to add: may be an ability that changes gravity on an area? May be make a stack of bool values for CanJump property? No, because abilities can be deactivated not in that order in which they were activated. I need a way to seperate ability logic that prevent the Rabbit from jumping from the Rabbit itself. One possible solution for this is making special checking event: class Rabbit { class CheckJumpEventArgs : EventArgs { public bool Veto { get; set; } } public event EventHandler<CheckJumpEvent> OnCheckJump; void Jump() { var args = new CheckJumpEventArgs(); if (OnCheckJump != null) OnCheckJump(this, args); if (!args.Veto) return; ... } } But it's a lot of code! A real Rabbit class would have a lot of properties like this (health and speed attributes, etc). I'm thinking of borrowing something from MVVM pattern where you have all the properties and methods of an object implemented in a way where they can be easily extended from outside. Then I want to use it like this: class FreezeAbility { void ActivateAbility() { _rabbit.CanJump.Push(ReturnFalse); } void DeactivateAbility() { _rabbit.CanJump.Remove(ReturnFalse); } // should be implemented as instance member // so it can be "unsubscribed" bool ReturnFalse(bool previousValue) { return false; } } Is this approach good? What also should I consider? What are other suitable options and patterns? Any ready to use solutions? UPDATE The question is not about how to add different behaviors to an object dynamically but how its (or its behavior) implementation can be extended with external logic. I don't need to add a different behavior but I need a way to modify an exitsing one and I also need a possibiliity to undo changes.

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• How do I learn algorithms?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be lear ning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• How to develop an english .com domain value rating algorithm?

  - by Tom

  I've been thinking about an algorithm that should rougly be able to guess the value of an english .com domain in most cases. For this to work I want to perform tests that consider the strengths and weaknesses of an english .com domain. A simple point based system is what I had in mind, where each domain property can be given a certain weight to factor it's importance in. I had these properties in mind: domain character length Eg. initially 20 points are added. If the domain has 4 or less characters, no points are substracted. For each extra character, one or more points are substracted on an exponential basis (the more characters, the higher the penalty). domain characters Eg. initially 20 points are added. If the domain is only alphabetic, no points are substracted. For each non-alhabetic character, X points are substracted (exponential increase again). domain name words Scans through a big offline english database, including non-formal speech, eg. words like "tweet" should be recognized. Question 1 : where can I get a modern list of english words for use in such application? Are these lists available for free? Are there lists like these with non-formal words? The more words are found per character, the more points are added. So, a domain with a lot of characters will still not get a lot of points. words hype-level I believe this is a tricky one, but this should be the cause to differentiate perfect but boring domains from perfect and interesting domains. For example, the following domain is probably not that valueable: www.peanutgalaxy.com The algorithm should identify that peanuts and galaxies are not very popular topics on the web. This is just an example. On the other side, a domain like www.shopdeals.com should ring a bell to the hype test, as shops and deals are quite popular on the web. My initial thought would be to see how often these keywords are references to on the web, preferably with some database. Question 2: is this logic flawed, or does this hype level test have merit? Question 3: are such "hype databases" available? Or is there anything else that could work offline? The problem with eg. a query to google is that it requires a lot of requests due to the many domains to be tested. domain name spelling mistakes Domains like "freemoneyz.com" etc. are generally (notice I am making a lot of assumptions in this post but that's necessary I believe) not valueable due to the spelling mistakes. Question 4: are there any offline APIs available to check for spelling mistakes, preferably in javascript or some database that I can use interact with myself. Or should a word list help here as well? use of consonants, vowels etc. A domain that is easy to pronounce (eg. Google) is usually much more valueable than one that is not (eg. Gkyld). Question 5: how does one test for such pronuncability? Do you check for consonants, vowels, etc.? What does a valueable domain have? Has there been any work in this field, where should I look? That is what I came up with, which leads me to my final two questions. Question 6: can you think of any more english .com domain strengths or weaknesses? Which? How would you implement these? Question 7: do you believe this idea has any merit or all, or am I too naive? Anything I should know, read or hear about? Suggestions/comments? Thanks!

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• Form submit in javascript

  - by zac

  Hi been wrestling this form and the last step (actually submitting) has me scratching my head. What I have so far is the form: <form id="theForm" method='post' name="emailForm"> <table border="0" cellspacing="2"> <td>Email <span class="red">*</span></td><td><input type='text'class="validate[required,custom[email]]" size="30"></td></tr> <td>First Name:</td><td><input type='text' name='email[first]' id='first_name' size=30></td></tr> <tr height="30"> <td cellpadding="4">Last Name:</td><td><input type='text' name='email[last]' id='e_last_name' size=30> <td>Birthday</td> <td><select name='month' style='width:70px; margin-right: 10px'> <option value=''>Month</option> <option value="1">Jan</option> <option value="2">Feb</option> .... </select><select name='day' style='width:55px; margin-right: 10px'> <option value=''>Day</option> <option value="1">1</option> <option value="2">2</option> ... <option value="31">31</option> </select><select name='year' style='width:60px;' > <option value=''>Year</option> <option value="2007">2007</option> <option value="2006">2006</option> <option value="2005">2005</option> ... </select> <input type='image' src='{{skin url=""}}images/email/signUpButt.gif' value='Submit' onClick="return checkAge()" /> <input type="hidden" id= "under13" name="under13" value="No"> and a script that checks the age and sets a cookie/changes display function checkAge() { var min_age = 13; var year = parseInt(document.forms["emailForm"]["year"].value); var month = parseInt(document.forms["emailForm"]["month"].value) - 1; var day = parseInt(document.forms["emailForm"]["day"].value); var theirDate = new Date((year + min_age), month, day); var today = new Date; if ( (today.getTime() - theirDate.getTime()) < 0) { var el = document.getElementById('emailBox'); if(el){ el.className += el.className ? ' youngOne' : 'youngOne'; } document.getElementById('emailBox').innerHTML = "<style type=\"text/css\">.formError {display:none}</style><p>Good Bye</p><p>You must be 13 years of age to sign up.</p>"; createCookie('age','not13',0) return false; } else { createCookie('age','over13',0) return true; }} that all seems to be working well.. just missing kind of a crucial step of actually submitting the form if it validates (if they pass the age question). So I am thinking that this will be wrapped in that script.. something in here : else { createCookie('age','over13',0) return true; } Can someone please help me figure out how I could handle this submit?

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• Can I retrieve objects from a complex query that limits results to fields from a single table?

  - by Sean Redmond

  I have a model whose rows I always want to sort based on the values in another associated model and I was thinking that the way to implement this would be to use set_dataset in the model. This is causing query results to be returned as hashes rather than objects, though, so none of the methods from the class can be used when iterating over the dataset. I basically have two classes class SortFields < Sequel::Model(:sort_fields) set_primary_key :objectid end class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid end Some backstory: the data is imported from a legacy system into mysql. The values in sort_fields are calculated from multiple other associated tables (some one-to-many, some many-to-many) according to some complicated rules. The likely solution will be to just add the values in sort_fields to items (I want to keep the imported data separate from the calculated data, but I don't have to). First, though, I just want to understand how far you can go with a dataset and still get objects rather than hashes. If I set the dataset to sort on a field in items like so class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset(order(:sortnumber)) end then the expected clause is added to the generated SQL, e.g.: >> Items.limit(1).sql => "SELECT * FROM `items` ORDER BY `sortnumber` LIMIT 1" and queries still return objects: >> Items.limit(1).first.class => Items If I order it by the associated fields though... class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset( eager_graph(:sort_fields). order(:sort1, :sort2, :sort3) ) end ...I get hashes ?> Items.limit(1).first.class => Hash My first thought was that this happens because all fields from sort_fields are included in the results and maybe if selected only the fields from items I would get Items objects again: class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset( eager_graph(:sort_fields). select(:items.*). order(:sort1, :sort2, :sort3) ) end The generated SQL is what I would expect: >> Items.limit(1).sql => "SELECT `items`.* FROM `items` LEFT OUTER JOIN `sort_fields` ON (`sort_fields`.`objectid` = `items`.`objectid`) ORDER BY `sort1`, `sort2`, `sort3` LIMIT 1" It returns the same rows as the set_dataset(order(:sortnumber)) version but it still doesn't work: >> Items.limit(1).first.class => Hash Before I add the sort fields to the items table so that they can all live happily in the same model, is there a way to tell Sequel to return on object when it wants to return a hash?

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• hosting simple python scripts in a container to handle concurrency, configuration, caching, etc.

  - by Justin Grant

  My first real-world Python project is to write a simple framework (or re-use/adapt an existing one) which can wrap small python scripts (which are used to gather custom data for a monitoring tool) with a "container" to handle boilerplate tasks like: fetching a script's configuration from a file (and keeping that info up to date if the file changes and handle decryption of sensitive config data) running multiple instances of the same script in different threads instead of spinning up a new process for each one expose an API for caching expensive data and storing persistent state from one script invocation to the next Today, script authors must handle the issues above, which usually means that most script authors don't handle them correctly, causing bugs and performance problems. In addition to avoiding bugs, we want a solution which lowers the bar to create and maintain scripts, especially given that many script authors may not be trained programmers. Below are examples of the API I've been thinking of, and which I'm looking to get your feedback about. A scripter would need to build a single method which takes (as input) the configuration that the script needs to do its job, and either returns a python object or calls a method to stream back data in chunks. Optionally, a scripter could supply methods to handle startup and/or shutdown tasks. HTTP-fetching script example (in pseudocode, omitting the actual data-fetching details to focus on the container's API): def run (config, context, cache) : results = http_library_call (config.url, config.http_method, config.username, config.password, ...) return { html : results.html, status_code : results.status, headers : results.response_headers } def init(config, context, cache) : config.max_threads = 20 # up to 20 URLs at one time (per process) config.max_processes = 3 # launch up to 3 concurrent processes config.keepalive = 1200 # keep process alive for 10 mins without another call config.process_recycle.requests = 1000 # restart the process every 1000 requests (to avoid leaks) config.kill_timeout = 600 # kill the process if any call lasts longer than 10 minutes Database-data fetching script example might look like this (in pseudocode): def run (config, context, cache) : expensive = context.cache["something_expensive"] for record in db_library_call (expensive, context.checkpoint, config.connection_string) : context.log (record, "logDate") # log all properties, optionally specify name of timestamp property last_date = record["logDate"] context.checkpoint = last_date # persistent checkpoint, used next time through def init(config, context, cache) : cache["something_expensive"] = get_expensive_thing() def shutdown(config, context, cache) : expensive = cache["something_expensive"] expensive.release_me() Is this API appropriately "pythonic", or are there things I should do to make this more natural to the Python scripter? (I'm more familiar with building C++/C#/Java APIs so I suspect I'm missing useful Python idioms.) Specific questions: is it natural to pass a "config" object into a method and ask the callee to set various configuration options? Or is there another preferred way to do this? when a callee needs to stream data back to its caller, is a method like context.log() (see above) appropriate, or should I be using yield instead? (yeild seems natural, but I worry it'd be over the head of most scripters) My approach requires scripts to define functions with predefined names (e.g. "run", "init", "shutdown"). Is this a good way to do it? If not, what other mechanism would be more natural? I'm passing the same config, context, cache parameters into every method. Would it be better to use a single "context" parameter instead? Would it be better to use global variables instead? Finally, are there existing libraries you'd recommend to make this kind of simple "script-running container" easier to write?

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• Inheriting XML files and modifying values

  - by Veehmot

  This is a question about concept. I have an XML file, let's call it base: <base id="default"> <tags> <tag>tag_one</tag> <tag>tag_two</tag> <tag>tag_three</tag> </tags> <data> <data_a>blue</data_a> <data_b>3</data_b> </data> </base> What I want to do is to be able to extend this XML in another file, modifying individual properties. For example, I want to inherit that file and make a new one with a different data/data_a node: <base id="green" import="default"> <data> <data_a>green</data_a> </data> </base> So far it's pretty simple, it replaces the old data/data_a with the new one. I even can add a new node: <base id="ext" import="default"> <moredata> <data>extended version</data> </moredata> </base> And still it's pretty simple. The problem comes when I want to delete a node or deal with XML Lists (like the tags node). How should I reference a particular index on a list? I was thinking doing something like: <base id="diffList" import="default"> <tags> <tag index="1">this is not anymore tag_two</tag> </tags> </base> And for deleting a node / array index: <base id="deleting" import="default"> <tags> <tag index="2"/> </tags> <data/> </base> <!-- This will result in an XML containing these values: --> <base> <tag>tag_one</tag> <tag>tag_two</tag> </base> But I'm not happy with my solutions. I don't know anything about XSLT or other XML transformation tools, but I think someone must have done this before. The key goal I'm looking for is ease to write the XML by hand (both the base and the "extended"). I'm open to new solutions besides XML, if they are easy to write manually. Thanks for reading.

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• Should I be using the command pattern? Seems like a lot of work...

  - by Fedor

  My Room class has a lot of methods I used before I decided to use the command pattern. Previously, I was invoking a lot of commands and now it seems I have to make a method in my roomParser class for every method. If I wanted to invoke say, setHotelCode I would have to create a method in roomParser that iterates through and invokes the method. Is this the way I should be using the command pattern? <?php interface Parseable { public function parse( $arr, $dept ); } class Room implements Parseable { protected $_adults; protected $_kids; protected $_startDate; protected $_endDate; protected $_hotelCode; protected $_sessionNs; protected $_minRate; protected $_maxRate; protected $_groupCode; protected $_rateCode; protected $_promoCode; protected $_confCode; protected $_currency = 'USD'; protected $_soapAction; protected $_soapHeaders; protected $_soapServer; protected $_responseXml; protected $_requestXml; public function __construct( $startdate,$enddate,$rooms=1,$adults=2,$kids=0 ) { $this->setNamespace(SESSION_NAME); $this->verifyDates( $startdate, $enddate ); $this->_rooms= $rooms; $this->_adults= $adults; $this->_kids= $kids; $this->setSoapAction(); $this->setRates(); } public function parse( $arr, $dept ) { $this->_price = $arr * $dept * rand(); return $this; } public function setNamespace( $namespace ) { $this->_sessionNs = $namespace; } private function verifyDates( $startdate, $enddate ) {} public function setSoapAction( $str= 'CheckAvailability' ) { $this->_soapAction = $str; } public function setRates( $rates='' ) { } public function setHotelCode($code ) { $this->_hotelCode = $code; } private function getSoapHeader() { return '<?xml version="1.0" encoding="utf-8"?> <soap:Header> </soap:Header>'; } private function getSoapFooter() { return '</soap:Envelope>'; } private function getSource() { return '<POS> <Source><RequestorId ID="" ID_Context="" /></Source> </POS>'; } function requestXml() { $this->_requestXml = $this->getSoapHeader(); $this->_requestXml .='<soap:Body></soap:Body>'; return $this->_requestXml; } private function setSoapHeaders ($contentLength) { $this->_soapHeaders = array('POST /url HTTP/1.1', 'Host: '.SOAP_HOST, 'Content-Type: text/xml; charset=utf-8', 'Content-Length: '.$contentLength); } } class RoomParser extends SplObjectStorage { public function attach( Parseable $obj ) { parent::attach( $obj ); } public function parseRooms( $arr, $dept ) { for ( $this->rewind(); $this->valid(); $this->next() ) { $ret = $this->current()->parse( $arr, $dept ); echo $ret->getPrice(), PHP_EOL; } } } $arrive = '12/28/2010'; $depart = '01/02/2011'; $rooms = new RoomParser( $arrive, $depart); $rooms->attach( new Room( '12/28/2010', '01/02/2011') ); $rooms->attach( new Room( '12/29/2010', '01/04/2011') ); echo $rooms->count(), ' Rooms', PHP_EOL; Edit: I'm thinking it may be easier if I made the RoomParser less generic by storing properties that all the objects will share. Though I'll probably have to make methods if I want to override for a certain object.

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