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• How do I update a webpage with the progress of a server-side task?

  - by Jim B

  Hi everyone, I'm working on a web project that takes the results from a survey type application, and runs them through a bunch of calculations to come up with some recommended suggestions for the user. Now, this calculation might take a minute or so, so I'd like to be able to give the user some update on it's progress. Obviously, the quick and dirty solution would be to put up a message along the lines of "Please wait while we calculate your recommendations" with a spinning gear type graphic. (or whatever, you get the point..). Once the task completes, I'd redirect to the results page. However, I'd like to do something a little more flashy. Maybe something along the lines of a progress bar, and even prompt the user with what's going on in the background. For example, give them a progress bar, with some text that says "Now processing suggestion 3 of 15; Multi-Vitamin" Any suggestions on how I could set this up? One way I'm thinking of doing it is to write the progress of the calculation method to the HttpContext, and slap up an update panel and timer that would show/refresh this info. I've also checked out maybe building a web service/method, and then poll that at some interval. Has anybody done something similar to this before? What worked for you? Thanks again! ~Jim

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• Use properties or methods to expose business rules in C#?

  - by Val

  I'm writing a class to encapsulate some business rules, each of which is represented by a boolean value. The class will be used in processing an InfoPath form, so the rules get the current program state by looking up values in a global XML data structure using XPath operations. What's the best (most idiomatic) way to expose these rules to callers -- properties or public methods? Call using properties Rules rules = new Rules(); if ( rules.ProjectRequiresApproval ) { // get approval } else { // skip approval } Call using methods Rules rules = new Rules(); if ( rules.ProjectRequiresApproval() ) { // get approval } else { // skip approval } Rules class exposing rules as properties public class Rules() { private int _amount; private int threshold = 100; public Rules() { _amount = someExpensiveXpathOperation; } // rule property public bool ProjectRequiresApproval { get { return _amount < threshold } } } Rules class exposing rules as methods public class Rules() { private int _amount; private int threshold = 100; public Rules() { _amount = someExpensiveXpathOperation; } // rule method public bool ProjectRequiresApproval() { return _amount < threshold; } } What are the pros and cons of one over the other?

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• Is there really such a thing as "being good at math"?

  - by thezhaba

  Aside from gifted individuals able to perform complex calculations in their head, I'm wondering if proficiency in mathematics, namely calculus and algebra, has really got to do with one's natural inclination towards sciences, if you can put it that way. A number of students in my calculus course pick up material in seemingly no time whereas I, personally, have to spend time thinking about and understanding most concepts. Even then, if a question that requires a bit more 'imagination' comes up I don't always recognize the concepts behind it, as is the case with calculus proofs, for instance. Nevertheless, I refuse to believe that I'm simply not made for it. I do very well in programming and software engineering courses where a lot of students struggle. At first I could not grasp what they found to be so difficult, but eventually I realized that having previous programming experience is a great asset -- once I've seen and made practical use of the programming concepts learning about them in depth in an academic setting became much easier as I have then already seen their use "in the wild". I suppose I'm hoping that something similar happens with mathematics -- perhaps once the practical idea behind a concept (which authors of textbooks sure do a great job of concealing..) is evident, understanding the seemingly dry and symbolic ideas and proofs would be more obvious? I'm really not sure. All I'm sure of is I'd like to get better at calculus, but I don't yet understand why some of us pick it up easily while others have to spend considerable amounts of time on it and still not have complete understanding if an unusual problem is given.

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• ojspc always returns 0 on errors

  - by Matt McCormick

  In my Ant build.xml file, I am trying to compile JSPs using ojspc. The files are being compiled, however, the build process is still running to completion when the JSP compilation has errors. This is part of my build.xml: <java fork="true" jar="${env.ORACLE_HOME}\j2ee\home\ojspc.jar" resultproperty="result"> <jvmarg value="-Djava.compiler=NONE"/> <arg value="-extend"/> <arg value="com.orionserver.http.OrionHttpJspPage"/> <arg value="-batchMask"/> <arg value="*.jsp"/> <arg value="${target-directory}/build/target/ear/${module-dir-name}-jsp.war"/> </java> <echo level="info">Result Property: ${result}</echo> I have tried setting the property failonerror="true" but that does not change anything. I receive the following output: [java] Detected archive, now processing contents of ../build/target/ear/web-module-jsp.war... [java] Setting up temp area... [java] Expanding archive in temp area... [java] C:\DOCUME~1\MMCCOR~1\LOCALS~1\Temp\tmp12940\_web_2d_inf\_jsp\_password.java:60: cannot resolve symbol [java] symbol : variable reqvst [java] location: class _web_2d_inf._jsp._password [java] out.print(reqvst.getAttribute("test")); [java] ^ [java] 1 error [java] Creating D:\eclipse-workspace\jdw\build\..\build\target\ear\web-module-jsp.war ... [java] Removing temp area... [echo] Result Property: 0 ...(more commands) BUILD SUCCESSFUL In the password.jsp file, I intentionally introduced an error to test. How can I get the build to fail on an error? At the Ant Java page, I am confused by: By default the return code of a is ignored. Alternatively, you can set resultproperty to the name of a property and have it assigned to the result code (barring immutability, of course). When you set failonerror="true", the only possible value for resultproperty is 0. Any non-zero response is treated as an error and would mean the build exits.

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• Some images fails to load on Windows Server 2008

  - by Guffa

  I have an application running on a Windows Server 2008, that is processing uploaded images. Currently it successfully processes about 8000 images per day, creating 11 different sizes of each image. The problem that I have is that sometimes the application fails to load some images, I get the error "System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI+.". The upload only accepts files with a JPEG extension (jpg/jpeg/jpe) or with a JPEG MIME type, and from what I can tell those images are really JPEG images. If I look at the image file in windows explorer on the server, it can successfully extract the thumbnail from the file, but if I try to open it, I get the error message "This is not a valid bitmap file, or it's format is not currently supported." from Paint. If I copy the image to my own computer, running Windows 7, there is no problem opening the image. It works in Paint, Windows Photo Viewer, Adobe Bridge, and Photoshop. If I try to load the image using Image.FromStream the same way as in the application running on the server, it loads just fine. (I have copied the file back to the server, and it still doesn't work, so there is nothing in the copying process that changes it.) When I look at the image information in Bridge, I see that the images are created using Picasa 3.0, but other than that I can't see anything special about them. I haven't yet found anyone having the same problem, or any known problems like this with the Picasa application. Has anyone had any similar problem, or know if there is something special about images created using Picasa? Is there any image codec that needs installing on the server to handle all kinds of JPEG images?

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• Generic validate input data via regex. Input error when match.count == 0

  - by Valamas

  Hi, I have a number of types of data fields on an input form, for example, a web page. Some fields are like, must be an email address, must be a number, must be a number between, must have certain characters. Basically, the list is undefinable. I wish to come up with a generic way of validating the data inputed. I thought I would use regex to validate the data. The fields which need validation would be related to a "regex expression" and a "regex error message" stating what the field should contain. My current mock up has that when the match count is zero, that would signify an error and to display the message. While still a white belt regex designer I have come to understand that in certain situations that it is difficult to write a regex which results in a match count of zero for every case. A complex regex case I looked for help on was Link Here. The forum post was a disaster because I confused people helping me. But one of the statements said that it was difficult to make a regex with a match count of zero meaning the input data was invalid; that the regex was very difficult to write that for. Does anyone have comments or suggestions on this generic validation system I am trying to create? thanks

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• C#, Can I check on a lock without trying to acquire it?

  - by Biff MaGriff

  Hello, I have a lock in my c# web app that prevents users from running the update script once it has started. I was thinking I would put a notification in my master page to let the user know that the data isn't all there yet. Currently I do my locking like so. protected void butRefreshData_Click(object sender, EventArgs e) { Thread t = new Thread(new ParameterizedThreadStart(UpdateDatabase)); t.Start(this); //sleep for a bit to ensure that javascript has a chance to get rendered Thread.Sleep(100); } public static void UpdateDatabase(object con) { if (Monitor.TryEnter(myLock)) { Updater.RepopulateDatabase(); Monitor.Exit(myLock); } else { Common.RegisterStartupScript(con, AlreadyLockedJavaScript); } } And I do not want to do if(Monitor.TryEnter(myLock)) Monitor.Exit(myLock); else //show processing labal As I imagine there is a slight possibility that it might display the notification when it isn't actually running. Is there an alternative I can use? Edit: Hi Everyone, thanks a lot for your suggestions! Unfortunately I couldn't quite get them to work... However I combined the ideas on 2 answers and came up with my own solution.

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• Building static (but complicated) lookup table using templates.

  - by MarkD

  I am currently in the process of optimizing a numerical analysis code. Within the code, there is a 200x150 element lookup table (currently a static std::vector < std::vector < double ) that is constructed at the beginning of every run. The construction of the lookup table is actually quite complex- the values in the lookup table are constructed using an iterative secant method on a complicated set of equations. Currently, for a simulation, the construction of the lookup table is 20% of the run time (run times are on the order of 25 second, lookup table construction takes 5 seconds). While 5-seconds might not seem to be a lot, when running our MC simulations, where we are running 50k+ simulations, it suddenly becomes a big chunk of time. Along with some other ideas, one thing that has been floated- can we construct this lookup table using templates at compile time? The table itself never changes. Hard-coding a large array isn't a maintainable solution (the equations that go into generating the table are constantly being tweaked), but it seems that if the table can be generated at compile time, it would give us the best of both worlds (easily maintainable, no overhead during runtime). So, I propose the following (much simplified) scenario. Lets say you wanted to generate a static array (use whatever container suits you best- 2D c array, vector of vectors, etc..) at compile time. You have a function defined- double f(int row, int col); where the return value is the entry in the table, row is the lookup table row, and col is the lookup table column. Is it possible to generate this static array at compile time using templates, and how?

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• IIS doesn't send two responses to the same client at the same time (only for ASP)

  - by dr. evil

  I've got 2 ASP pages. I do a request to the first page from Firefox (which takes 30 seconds to process on server-side), and during the execution of 30 seconds I do another request from Firefox to the second page (takes less than 1 second in server-side), but it does come after 31 second. Because it waits first requests to finish. When I request to the first page from Firefox and then request the second page from IE it's just instant. So basically ASP - IIS 6 somehow limiting every client to one request (long processing request) at a time. I need to get around this problem in my .NET client application. This is tested in 3 different systems. If you want to test you can try the ASP scripts at the end. This behaviour is same in a long SQL execution or just in a time consuming ASP operation. Note: It's not about HTTP Keep Alive It's not about persistent connection limit (we tried to increase this in firefox and in .NET with Net.ServicePointManager.DefaultConnectionLimit) It's not about User Agent This doesn't happen in ASP.NET so I assume it's something to the with ASP.dll I'm trying to solve this on the client not the server. I don't have direct control over the server it's a 3rd party solution. Is there any way to get around this? Sample ASP Code: First ASP: <% Set cnn = Server.CreateObject("Adodb.Connection") cnn.Open "Provider=sqloledb;Data Source=.;Initial Catalog=master;User Id=sa;Password=;" cnn.Execute("WAITFOR DELAY '0:0:30'") cnn.Close %> Second ASP: <% Response.Write "bla bla" %>

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• getting data from dynamic schema

  - by coure2011

  I am using mongoose/nodejs to get data as json from mongodb. For using mongoose I need to define schema first like this var mongoose = require('mongoose'); var Schema = mongoose.Schema; var GPSDataSchema = new Schema({ createdAt: { type: Date, default: Date.now } ,speed: {type: String, trim: true} ,battery: { type: String, trim: true } }); var GPSData = mongoose.model('GPSData', GPSDataSchema); mongoose.connect('mongodb://localhost/gpsdatabase'); var db = mongoose.connection; db.on('open', function() { console.log('DB Started'); }); then in code I can get data from db like GPSData.find({"createdAt" : { $gte : dateStr, $lte: nextDate }}, function(err, data) { res.writeHead(200, { "Content-Type": "application/json", "Access-Control-Allow-Origin": "*" }); var body = JSON.stringify(data); res.end(body); }); How to define scheme for a complex data like this, you can see that subSection can go to any deeper level. [ { 'title': 'Some Title', 'subSection': [{ 'title': 'Inner1', 'subSection': [ {'titile': 'test', 'url': 'ab/cd'} ] }] }, .. ]

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• SQL Server error handling: exceptions and the database-client contract

  - by gbn

  We’re a team of SQL Servers database developers. Our clients are a mixed bag of C#/ASP.NET, C# and Java web services, Java/Unix services and some Excel. Our client developers only use stored procedures that we provide and we expect that (where sensible, of course) they treat them like web service methods. Some our client developers don’t like SQL exceptions. They understand them in their languages but they don’t appreciate that the SQL is limited in how we can communicate issues. I don’t just mean SQL errors, such as trying to insert “bob” into a int column. I also mean exceptions such as telling them that a reference value is wrong, or that data has already changed, or they can’t do this because his aggregate is not zero. They’d don’t really have any concrete alternatives: they’ve mentioned that we should output parameters, but we assume an exception means “processing stopped/rolled back. How do folks here handle the database-client contract? Either generally or where there is separation between the DB and client code monkeys. Edits: we use SQL Server 2005 TRY/CATCH exclusively we log all errors after the rollback to an exception table already we're concerned that some of our clients won't check output paramaters and assume everything is OK. We need errors flagged up for support to look at. everything is an exception... the clients are expected to do some message parsing to separate information vs errors. To separate our exceptions from DB engine and calling errors, they should use the error number (ours are all 50,000 of course)

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• Why would paperclip not assign an ID to my uploaded photos?

  - by Trip

  I just deployed to a cluster server, and my delayed_jobs recipe was overwritten in the process. I solved that, delayed_jobs is up and running but can't find the ID of images that are uploaded. The images are saved correctly : Processing PhotosController#create (for 173.161.167.41 at 2010-06-01 05:09:14) [POST] Parameters: {"Filename"="1.jpg", "gallery_id"="1298", "action"="create", "amp"=nil, "authenticity_token"="qmbnpwFY8a5E3YtS/4fMWF/Z8evCE4hMxqKVJw0I7Ek=", "Upload"="Submit Query", "controller"="photos", "organization_id"="470", "_hq_channel_session"="BAh7CSIYdXNlcl9jcmVkZW50aWFsc19pZGkHIhV1c2VyX2NyZWRlbnRpYWxzIgGAOGRlZDc0NGJlOWU3NTNlNDFlYmVlMDdjMzIzYjA1ZjQxNGE5ZDY4YjNmYjFmNjNkMDQ2OWY2ZDQyOTljZDhiMDFlNmRkMDljNThmMzBmOWJhMTIwNDhkMDI5MTMxYmU5MDczYjIxZmI4YmQxMDVlMTBmNjZmOWFhODE1ZTBjMGM6EF9jc3JmX3Rva2VuIjFxbWJucHdGWThhNUUzWXRTLzRmTVdGL1o4ZXZDRTRoTXhxS1ZKdzBJN0VrPToPc2Vzc2lvbl9pZCIlMjAwMDQ3ZDQ3ZWUyZTgzODIxYzdjOGI3OTdmZGJiMDM=--ac6aa580262938bf5a4d6b9a740722b680eb5d48", "Filedata"=#} [paperclip] Saving attachments. [paperclip] saving /data/HQ_Channel/releases/20100530153454/public/system/photos/9253/original/1.jpg [paperclip] Saving attachments. [paperclip] Saving attachments. Completed in 127ms (View: 2, DB: 91) | 200 OK [http://invent.hqchannel.com/organizations/470/media/galleries/1298/photos?_hq_channel_session=BAh7CSIYdXNlcl9jcmVkZW50aWFsc19pZGkHIhV1c2VyX2NyZWRlbnRpYWxzIgGAOGRlZDc0NGJlOWU3NTNlNDFlYmVlMDdjMzIzYjA1ZjQxNGE5ZDY4YjNmYjFmNjNkMDQ2OWY2ZDQyOTljZDhiMDFlNmRkMDljNThmMzBmOWJhMTIwNDhkMDI5MTMxYmU5MDczYjIxZmI4YmQxMDVlMTBmNjZmOWFhODE1ZTBjMGM6EF9jc3JmX3Rva2VuIjFxbWJucHdGWThhNUUzWXRTLzRmTVdGL1o4ZXZDRTRoTXhxS1ZKdzBJN0VrPToPc2Vzc2lvbl9pZCIlMjAwMDQ3ZDQ3ZWUyZTgzODIxYzdjOGI3OTdmZGJiMDM%3D--ac6aa580262938bf5a4d6b9a740722b680eb5d48&authenticity_token=qmbnpwFY8a5E3YtS%2F4fMWF%2FZ8evCE4hMxqKVJw0I7Ek%3D] And then delayed_jobs keeps spinning around in circles on this one : 2010-06-01T05:09:02-0700: * [Worker(delayed_job host:ip-10-251-197-159 pid:19994)] acquired lock on PhotoJob 2010-06-01T05:09:02-0700: * [JOB] delayed_job host:ip-10-251-197-159 pid:19994 failed with ActiveRecord::RecordNotFound: Couldn't find Photo with ID=9247 - 0 failed attempts 2010-06-01T05:09:02-0700: * [Worker(delayed_job host:ip-10-251-197-159 pid:19994)] acquired lock on PhotoJob 2010-06-01T05:09:02-0700: * [JOB] delayed_job host:ip-10-251-197-159 pid:19994 failed with ActiveRecord::RecordNotFound: Couldn't find Photo with ID=9245 - 0 failed attempts 2010-06-01T05:09:02-0700: * [Worker(delayed_job host:ip-10-251-197-159 pid:19994)] acquired lock on PhotoJob So what I get is that the photos are not being assigned ID's by paperclip. Anyone know where I could poke and pry from here? UPDATE: I created a clone application on a single server. And there are no problems. The images on the cluster do show up (occassionally). If I keep clicking on the folders that lead to photos, it will 50% of the time return a 404 with it not being able to find the photo, and the other half it will present the photo. So the problem has got to be with the server interaction between the ActiveRecord through multiple servers.

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• Host WCF in MVC2 Site

  - by Basiclife

  Hi, We've got a very large, complex MVC2 website. We want to add an API for some internal tools and decided to use WCF. Ideally, we want MVC itself to host the WCF service. Reasons include: Although there's multiple tiers to the application, some functionality we'd like in the API requires the website itself (e.g. formatting emails). We use TFS to auto-build (continuous integration) and deploy - The less we need to modify the build and release mechanism the better We use the Unity container and Inversion of Control throughout the application. Being part of the Website would allow us to re-use configuration classes and other helper methods. I've written a custom ServiceBehavior which in turn has a custom InstanceProvider - This allows me to instantiate and configure a container which is then used to service all requests for class instances from WCF. So my question is; Is it possible to host a WCF service from within MVC itself? I've only had experience in Services / Standard Asp.Net websites before and didn't realise MVC2 might be different until I actually tried to wire it into the config and nothing happened. After some googling, there don't seem to be many references to doing this - so thought I'd ask here.

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• Matching innermost braces with regex or strpos?

  - by rich97

  I have a sort of mini parsing syntax I made up to help me streamline my view code in cakephp. Basically I have created a table helper which, when given a dataset and (optionally) a set of options for how to format the data will render out a table, as opposed to me looping though the data and editing it manually. It allows the user to be as complex or as simple as they like, it can get pretty powerful. However, In order to achieve this I had to make a simple parsing syntax. As a quick example the user would do something like so: $this->Table->data = $userData; $this->Table->elements['td']['data'] = array( '{:User.username:}', '{:User.created:}' => array('Time::nice') ); echo $this->Table->render(); And when rendering the table would then generate: <table> <tbody> <tr><td>rich97</td><td>Sun 21st 02:30pm</td></tr> </tbody> </table> The problem occurs then I try to nest the braces like so: {:User.levels.iconClasses.{:User.access:}:} Is there anyway I can only get the inner most brackets on the first time round and loop though until there are no matches? Or even do it in one go? Or even better use strpos? Here is my regex as it stands: '/\{\:([^}]+)\:\}/'

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• Create a real time web application using .net framework and azure - very confused

  - by test

  Let us say I would like a simple (yet complex) web application where there is continuous READING AND WRITING to the sql azure database. Let us say I am tracking a location, and I would like it to be updated very frequently (lets take the worst case: 1 second). From the little knowledge I have, I think that this involves the use of the database to continuously write the location to the database, and continuously read from the database to update another person through a website. Do you please have any suggestion which technologies can I use? Is there a simple way? I heard about node.js, signalR. I have no idea how to use them, if they are really what I need. the last tutorial I checked out simply uses a while(true) loop..but I don't think that that's something good to keep a thread continuously busy... Do I have to create some background task? Do I have to create some web service? This is a school project and I wish not to go for the most difficult option, but if there is some sort of solution, challenge accepted :) Can you please help me? Since I have asked many questions here and yet I have no solution in mind

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• What are CAD apps written in, and how are they organized ?

  - by ldigas

  What are CAD applications (Rhino, Autocad) of today written in and how are they organized internally ? I gave as an example, Autocad and Rhino, although I would love to hear of other examples as well. I'm particularly interested in knowing what is their backend written in (multilanguage ?) and how is it organized, and how do they handle their frontend (GUI) in real time ? Do they use native windows API's or some libraries of their own, since I imagine, as good as may be, the open source solutions on today's market won't cut it. I may be wrong ... As most of you who have used them know, they handle amongs other things relatively complex rotational operations in realtime (shading is not interesting me). I've been doing some experiments with several packages recently, and for some larger models found that there is considerable difference in speed in, for example, programed rotation (big full ship models) amongst some of them (which I won't name). So I'm wondering about their internals ... Also, if someone knows of some book on the subject, I'd be interested to hear of it.

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• How I May Have Taken A Wrong Path in Programming

  - by Ygam

  I am in a major stump right now. I am a BSIT graduate, but I only started actual programming less than a year ago. I observed that I have the following attitude in programming: I tend to be more of a purist, scorning unelegant approaches to solving problems using code I tend to look at anything in a large scale, planning everything before I start coding, either in simple flowcharts or complex UML charts I have a really strong impulse on refactoring my code, even if I miss deadlines or prolong development times I am obsessed with good directory structures, file naming conventions, class, method, and variable naming conventions I tend to always want to study something new, even, as I said, at the cost of missing deadlines I tend to see software development as something to engineer, to architect; that is, seeing how things relate to each other and how blocks of code can interact (I am a huge fan of loose coupling) i.e the OOP thinking I tend to combine OOP and procedural coding whenever I see fit I want my code to execute fast (thus the elegant approaches and refactoring) This bothers me because I see my colleagues doing much better the other way around (aside from the fact that they started programming since our first year in college). By the other way around I mean, they fire up coding, gets the job done much faster because they don't have to really look at how clean their codes are or how elegant their algorithms are, they don't bother with OOP however big their projects are, they mostly use web APIs, piece them together and voila! Working code! CLients are happy, they get paid fast, at the expense of a really unmaintainable or hard-to-read code that lacks structure and conventions, or slow executions of certain actions (which the common reasoning against would be that internet connections are much faster these days, hardware is more powerful). The excuse I often receive is clients don't care about how you write the code, but they do care about how long you deliver it. If it works then all is good. Now, did my "purist" approach to programming may have been the wrong way to start programming? Should I just dump these purist concepts and just code the hell up because I have seen it: clients don't really care how beautifully coded it is?

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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 strict should I be in the "do the simplest thing that could possible work" while doing TDD

  - by Support - multilanguage SO

  For TDD you have to Create a test that fail Do the simplest thing that could possible work to pass the test Add more variants of the test and repeat Refactor when a pattern emerge With this approach you're supposing to cover all the cases ( that comes to my mind at least) but I'm wonder if am I being too strict here and if it is possible to "think ahead" some scenarios instead of simple discover them. For instance, I'm processing a file and if it doesn't conform to a certain format I am to throw an InvalidFormatException So my first test was: @Test void testFormat(){ // empty doesn't do anything... processor.validate("empty.txt"); try { processor.validate("invalid.txt"); assert false: "Should have thrown InvalidFormatException"; } catch( InvalidFormatException ife ) { assert "Invalid format".equals( ife.getMessage() ); } } I run it and it fails because it doesn't throw an exception. So the next thing that comes to my mind is: "Do the simplest thing that could possible work", so I : public void validate( String fileName ) throws InvalidFormatException { if(fileName.equals("invalid.txt") { throw new InvalidFormatException("Invalid format"); } } Doh!! ( although the real code is a bit more complicated, I found my self doing something like this several times ) I know that I have to eventually add another file name and other test that would make this approach impractical and that would force me to refactor to something that makes sense ( which if I understood correctly is the point of TDD, to discover the patterns the usage unveils ) but: Q: am I taking too literal the "Do the simplest thing..." stuff?

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• Retrieve class name hierarchy as string

  - by Jeff Wain

  Our system complexity has risen to the point that we need to make permission names tied to the client from the database more specific. In the client, permissions are referenced from a static class since a lot of client functionality is dependent on the permissions each user has and the roles have a ton of variety. I've referenced this post as an example, but I'm looking for a more specific use case. Take for instance this reference, where PermissionAlpha would be a const string: return HasPermission(PermissionNames.PermissionAlpha); Which is great, except now that things are growing more complex the classes are being structured like this: public static class PermissionNames { public static class PermissionAlpha { public const string SubPermission; } } I'm trying to find an easy way to reference PermissionAlpha in this new setup that will act similar to the first declaration above. Would the only way to do this be to resort to pulling the value of the class name like in the example below? I'm trying to keep all the names in one place that can be reference anywhere in the application. public static class PermissionAlpha { public static string Name { get { return typeof(PermissionAlpha).Name; } } }

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• Object Design catalog and resources

  - by Tauren

  I'm looking for web sites, books, or other resources that provide a catalog of object designs used in common scenarios. I'm not looking for generic design patterns, but for samples of actual object designs that were used to solve real problems. For instance, I'm about to build an internal messaging system for a web application, similar to Facebook's messaging system. This system will allow administrators to send messages to all members, to selected groups of members, or to individuals. Members can send messages to other members or groups of members. Fairly common stuff and a feature that I'm sure thousands of web applications require. I know each situation is different and there are a million ways to design this solution. Although this scenario isn't really all that complex, I'm sure the basic design of the necessary objects and relationships for a system like this has already been done many times. It would be nice to review other similar designs before building my own. Is there a place where people can share their designs and others can browse/search through the catalog to review and provide feedback on them? StackOverflow could be used to a degree for this, but doesn't really provide a catalog of designs. Any other resources that would relate?

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• [C#] how to do Exception Handling & Tracing

  - by shrimpy

  Hi all, i am reading some C# books, and got some exercise don't know how to do, or not sure what does the question mean. Problem: After working for a company for some time, your skills as a knowledgeable developer are recognized, and you are given the task of “policing” the implementation of exception handling and tracing in the source code (C#) for an enterprise application that is under constant incremental development. The two goals set by the product architect are: 100% of methods in the entire application must have at least a standard exception handler, using try/catch/finally blocks; more complex methods must also have additional exception handling for specific exceptions All control flow code can optionally write “tracing” information to assist in debugging and instrumentation of the application at run-time in situations where traditional debuggers are not available (eg. on staging and production servers). (i am not quite understand these criterias, i came from the java world, java has two kind of exception, check and unchecked exception. Developer must handle checked exception, and do logging. about unchecked exception, still do logging maybe, but most of the time we just throw it. however here comes to C#, what should i do????) Question for Problem: List rules you would create for the development team to follow, and the ways in which you would enforce rules, to achieve these goals. How would you go about ensuring that all existing code complies with the rules specified by the product architect; in particular, what considerations would impact your planning for the work to ensure all existing code complies?

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• open current page in new window including query string

  - by Hatch

  First of all, I am a total dud at all things related to web developement, so please bear with me here. I suspect this question is laughable for the web guys, but unfortunately I can't figure this out. Here goes: I have an application, that does some processing, writes some result files and then displays the results in an embedded IE browser control. This is done by navigating the browser control to a local html file together with a query string containing the generated result files to display it all. The link target would look something like: c:\SomeFolder\results.htm?results=file%201.xml;file%202.xml;file%203.xml So far, everything's fine. However, in the html page is a href that is suppossed to open up the exact same just in a normal browser window. What I thought would work is: <a href="#" target="_blank">Show in browser</a> Since it is a link in an html page displayed in an IE control, the link will open up in IE no matter what the default browser might be. This works for IE7 and 8, but not for IE6. With IE6 the query string gets cut off and the browser opens file://c:/results/results.htm# without the query string. I am sure there must be a much better way to do this without the # and which would work in all IEs. How would the pros solve this?

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• Get Mail with PHP and IMAP in Gmail just loading

  - by Oscar Godson

  I'm not sure why. Ive tried a bunch of different code. Wrote it myself, and copied other people's tutorials but every bit of code it's loading forever and eventually stops due to script processing times on the server. Does anyone know why? Oh, and IMAP is turned on, i get IMAP / Exchange on my iPhone from this same account fine. And IMAP is turned on in my version of PHP (checked with phpinfo they all say enabled.) <?php /* connect to gmail */ $hostname = '{imap.gmail.com:993/imap/ssl}INBOX'; $username = '[email protected]'; $password = 'xxxxxx'; /* try to connect */ $inbox = imap_open($hostname,$username,$password) or die('Cannot connect to Gmail: ' . imap_last_error()); /* grab emails */ $emails = imap_search($inbox,'ALL'); /* if emails are returned, cycle through each... */ if($emails) { /* begin output var */ $output = ''; /* put the newest emails on top */ rsort($emails); /* for every email... */ foreach($emails as $email_number) { /* get information specific to this email */ $overview = imap_fetch_overview($inbox,$email_number,0); $message = imap_fetchbody($inbox,$email_number,2); /* output the email header information */ $output.= '<div class="toggler '.($overview[0]->seen ? 'read' : 'unread').'">'; $output.= '<span class="subject">'.$overview[0]->subject.'</span> '; $output.= '<span class="from">'.$overview[0]->from.'</span>'; $output.= '<span class="date">on '.$overview[0]->date.'</span>'; $output.= '</div>'; /* output the email body */ $output.= '<div class="body">'.$message.'</div>'; } echo $output; } /* close the connection */ imap_close($inbox); ?

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• Anyone NOT using a Web Framework? Why?

  - by tom

  I'm well aware of the many reasons to use a web framework. I'm just wondering whether anyone out there is using absolutely no web framework whatsoever to develop their web projects. I would really love to know the reason(s) why you're not using a web framework. For the sake of this discussion, your programming language of choice does not matter. Some possibilities for discussion: You don't hide behind an ORM. You don't rely on any sort of templating system. You think MVC is a really nice TLA but lacks an essential vowel or two. No need for any additional javascript framework tomfoolery. You just write as much code as possible in your native programming language(s). Summary of reasons thus far: Language learning opportunities. Specific performance reasons (write-intensive transaction processing). Seeking more nuanced control over your data and applications (less abstraction). You're building your own framework! Prove to yourself that you can succeed (or fail) just like the big framework-building gurus. Integration issues with unpopular/legacy technologies (exotic databases or protocols come to mind). Big company, lots of code, no talent nor buy-in present to move to a web framework. Some frameworks really lock you in and cannot perpetually grow along with your needs. These few black sheep don't make it easy to jump outside of the framework, write some custom code, and easily jump back in. When you finally escape the asylum, you'll never look back.

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