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• In Symfony, how can I add a 'selected' class to the currently selected page in my navigation?

  - by Jon Winstanley

  My navigation is written in the layout.php template It looks like this: <ul id="nav"> <li><a href="item1">Item 1</a></li> <li><a href="item1">Item 2</a></li> <li><a href="item1">Item 3</a></li> <li><a href="item1">Item 4</a></li> </ul> What is the best way to get a class="current" on the currently selected page?

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• Where to execute extra logic for linq to entities query?

  - by Inez

  Let say that I want to populate a list of CustomerViewModel which are built based on Customer Entity Framework model with some fields (like Balance) calculated separately. Below I have code which works for lists - it is implemented in my service layer, but also I want to execute this code when I just get one item from the database and execute is as well in different services where I'm accessing Customers data as well. How should I do this to ensure performance but to to not duplicate code - the one for calculating Balance? public List<CustomerViewModel> GetCustomerViewModelList() { IQueryable<CustomerViewModel> list = from k in _customerRepository.List() select new CustomerViewModel { Id = k.Id, Name = k.Name, Balance = k.Event.Where(z => z.EventType == (int) EventTypes.Income).Sum(z => z.Amount) }; return list.ToList(); }

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• What causes this retainAll exception?

  - by Joren

  java.lang.UnsupportedOperationException: This operation is not supported on Query Results at org.datanucleus.store.query.AbstractQueryResult.contains(AbstractQueryResult.java:250) at java.util.AbstractCollection.retainAll(AbstractCollection.java:369) at namespace.MyServlet.doGet(MyServlet.java:101) I'm attempting to take one list I retrieved from a datastore query, and keep only the results which are also in a list I retrieved from a list of keys. Both my lists are populated as expected, but I can't seem to user retainAll on either one of them. // List<Data> listOne = new ArrayList(query.execute(theQuery)); // DatastoreService ds = DatastoreServiceFactory.getDatastoreService(); // List<Data> listTwo = new ArrayList(ds.get(keys).values()); // listOne.retainAll(listTwo);

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• Php fetch rows from multiple MySQL tables

  - by Jon McIntosh

  Right now I am fetching all of the rows from one of my tables: query = "SELECT * FROM thread WHERE threadid = 2 ORDER BY threadid DESC"; $result = mysql_query($query); $num_rows = mysql_num_rows($result); if((!is_bool($result) || $result) && $num_rows) { while($row = mysql_fetch_array($result)) { $thread = $row['title']; $threadID = $row['threadid']; $poster = $row['postusername']; } What I want to do is go to another table on my database: "post_display", and get the row 'text' where the threadid = 2.

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• Anybody using Qi4J

  - by Jon

  I was reading an InfoQ article on Composite Oriented Programming earlier on: http://www.infoq.com/articles/Composite-Programming-Qi4j I was interested in finding out whether anybody is currently using (or has used) the Qi4j framework at all? How does it compares to using a traditional dependency injection framework such as Spring for wiring classes together. Is the resulting object graph (based on mixins rather than classes) easier to deal with from a maintenance point of view?

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• Views jump during ViewDidLoad

  - by Jon-Paul

  Hi, I have a custom button, subclassed from UIButton that is initialised as below (obviously all the button does is use a custom font). @implementation HWButton - (id)initWithCoder:(NSCoder *)decoder { if (self = [super initWithCoder: decoder]) { [self.titleLabel setFont:[UIFont fontWithName: @"eraserdust" size: self.titleLabel.font.pointSize]]; } return self; } So far so good. But when I use the custom class in my nib and launch the app, the button initially displays for a split second as tiny with small text, then grows. So the outcome is what I want, but I don't want to see the transition. Can anyone put me right? Thanks. JP

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• Poor DB4O performance - What am I doing wrong?

  - by Jon

  I read Rob Conery's post about Object databases and thought I'd give it a go. I have a class lets say Book with 15 properties mostly string, some int, one Datetime and 2 decimals. I used Rob's code to open the database file etc to test on a Winforms project not a Web project. So I did the following: for(int i = 0; i < 1000000; i++) { var Book = new Book(); //Assign variables s.Save(Book); } s.CommitChanges(); This took at least a couple of minutes. I then tried to retrieve all data to test speed: var spp = s.All<Passports>(); This one line was quick, however, then doing: sppp.Count() as well as a seperate test doing a foreach loop and incrementing a counter took a couple of minutes. This seems quite slow to me. Am I doing something wrong or am I expecting too much?

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• How to automatically insert a class notation using eclipse templates?

  - by João Paulo G. Piccinini

  Does anybody know how to insert a "@RunWith anotation" above the class signature, using eclipse templates? Ex.: @RunWith(Parameterized.class) public class MyClassTest { ... @Parameters public static Collection<Object[]> parameters() { List<Object[]> list = new ArrayList<Object[]>(); list.add(new Object[] { "mind!", "find!" }); list.add(new Object[] { "misunderstood", "understood" }); return list; } ... } __ Template: // TODO: move this '@RunWith(Parameterized.class)' to class anotation @Parameters public static Collection<Object[]> parameters() { ${type:elemType(collection)}<Object[]> parametersList = new ${type:elemType(collection)}<Object[]>(); ${cursor}// TODO: populate collection return parametersList; } __ Thanks for the help!

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• Issue using Visual Studio 2010 compiled C++ DLL in Windows 2000

  - by Jon Tackabury

  I have a very simple DLL written in unmanaged C++ that I access from my application. I recently switch to Visual Studio 2010, and the DLL went from 55k down to 35k with no code changes, and now it will no longer load in Windows 2000. I didn't change any code or compiler settings. I have my defines setup for 0x0500, which should include Windows 2000 support. Has anyone else run into this, or have any ideas of what I can do?

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• Are there any generic shipping calculators out there for DJango?

  - by Jon Cage

  I'm in the process of settings up a website (I'm using DJango) to begin selling some toys I build and need a way of calculating shipping costs for my customers. Are there any (preferably free) shipping calculators which accept a customers address and return the cost for different delivery companies / delivery options? It would be nice if the API could indicate cost vs delivery time. We'll be shipping world-wide if that makes a difference?

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• When doing a Schema Export with hbm2ddl, is there a way to specify that you DO NOT want Nullable For

  - by Jon Erickson

  The DDL that is being created is putting all of my many to many associations into 1 table, but I actually want each many to many association in its' own table (for other reasons) Right now hbm2ddl is creating this table (only Table1Key OR Table2Key OR Table3Key should be filled out for any given record, causing this table to have nullable foreign keys): +-----------+ | xRef | +-----------+ | Table1Key | | Table2Key | | Table3Key | | RiskKey | +-----------+ I want hbm2ddl to create the following 3 tables so that there are no nullable foreign keys. +-----------+ +-----------+ +-----------+ | xRef1 | | xRef2 | | xRef3 | +-----------+ +-----------+ +-----------+ | Table1Key | | Table2Key | | Table3Key | | RiskKey | | RiskKey | | RiskKey | +-----------+ +-----------+ +-----------+

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• Exiting from the Middle of an Expression Without Using Exceptions

  - by Jon Purdy

  Is there a way to emulate the use of flow-control constructs in the middle of an expression? Is it possible, in a comma-delimited expression x, y, for y to cause a return? Edit: I'm working on a compiler for something rather similar to a functional language, and the target language is C++. Everything is an expression in the source language, and the sanest, simplest translation to the destination language leaves as many things expressions as possible. Basically, semicolons in the target language become C++ commas. In-language flow-control constructs have presented no problems thus far; it's only return. I just need a way to prematurely exit a comma-delimited expression, and I'd prefer not to use exceptions unless someone can show me that they don't have excessive overhead in this situation. The problem of course is that most flow-control constructs are not legal expressions in C++. The only solution I've found so far is something like this: try { return x(), // x(); (1 ? throw Return(0) : 0); // return 0; } catch (Return& ret) { return ref.value; } The return statement is always there (in the event that a Return construct is not reached), and as such the throw has to be wrapped in ?: to get the compiler to shut up about its void result being used in an expression. I would really like to avoid using exceptions for flow control, unless in this case it can be shown that no particular overhead is incurred; does throwing an exception cause unwinding or anything here? This code needs to run with reasonable efficiency. I just need a function-level equivalent of exit().

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• Java paint speed relative to color model

  - by Jon

  I have a BufferedImage with an IndexColorModel. I need to paint that image onto the screen, but I've noticed that this is slow when using an IndexColorModel. However, if I run the BufferedImage through an identity affine transform it creates an image with a DirectColorModel and the painting is significantly faster. Here's the code I'm using AffineTransformOp identityOp = new AffineTransformOp(new AffineTransform(), AffineTransformOp.TYPE_BILINEAR); displayImage = identityOp.filter(displayImage, null); I have three questions 1. Why is painting the slower on an IndexColorModel? 2. Is there any way to speed up the painting of an IndexColorModel? 3. If the answer to 2. is no, is this the most efficient way to convert from an IndexColorModel to a DirectColorModel? I've noticed that this conversion is dependent on the size of the image, and I'd like to remove that dependency. Thanks for the help

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• Get the ID of user that like my page.

  - by jon

  Hello I would like to know if there is any API feature that can tell me which users liked my application page. I know that it is possible to check if a user is a fan of any given Page using page.isFan verification or to get the number of fans. But is it possible to get the fans' User ID? If so, is it possible to get that data ordered by the date they became fans of the page? For exemple usign FQL i can get the user ID of someone o like an facebook object like post or photo. http://developers.facebook.com/docs/reference/fql/like Can i do this for the people who liked my page? Thanks for any help or guideline .

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• using extends with Java Generics

  - by Sandro

  Lets say that I have the following code: public class Shelter<A extends Animal, B extends Animal> { List<A> topFloor = new Vector<A>(); List<B> bottomFloor = new Vector<B>(); public A getFirstTopFloorAnimal(){return topFloor.firstElement();} public B getFirstBottomFloorAnimal(){return bottomFloor.firstElement();} //This compiles but when I try to use it, it only returns objects public List<Animal> getAnimals() { Vector a = new Vector(topFloor); a.addAll(bottomFloor); return a; } } Now for somereason the following code compiles. But when I try to use getAnimals() I get a of objects instead of Animal. Any ideas why this is? Does this have to do with the List is NOT a List idea in the Generics tutorial? Thank you.

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• Automatic e-mail processing

  - by Jon Harrop

  I'd like to write a .NET application in F# to automate some of the processing of my e-mails. For example, when an order comes in my program might compute a new htpasswd from the e-mail's contents, upload it to our web server and reply to the customer with login details. How do people do this? I've tried Outlook 2007 automation but it just prompts the user for security and my attempts to get it to stop doing this have failed so I cannot automate anything with it. Is there a .NET-friendly e-mail client I can use more easily? This has been so tedious that I'm seriously considering writing my own .NET-friendly e-mail client...

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• From Pocket to Instapaper

  - by Michael Freidgeim

  Some time ago I’ve described the issues that I’ve had since a new version of Read It Later, named Pocket, was introduced.I’ve waited with hope for a new upgrade, but I had a huge disappointment with the latest version 16 June 2012. It didn’t fixed any of the two major problems, that I  experienced since new Pocket was introduced-  1. iPad app still didn’t show many of the saved links. 2. ability to rename articles on iPad still wasn’t restored.I’ve posted the message into their forum. They did not show my comment on their forum( I would name it censorship, not moderation), but a few days ago I’ve received an email, recommending “try logging out of the app on your iPad, and back in again.” Their suggestion helped,  but I don’t understand, why it is not posted as a recommendation on their support site.So I decided to try InstAPaper on my iPad, Previously I’ve used it for Kindle. I never considered it before on iPad, because there were no free demo and I was very satisfied with RIL free and then RIL Pro. Currently InstAPaper cost $3, so the price is not an issue.I’ve checked that it has most of features that I am using(e.g. renaming, folders) and I am quite happy with it now. Actually I am using Pocket (or RIL free) for old bookmarks( I have 1000+ stored on my iPad) and for new bookmarks I am using InstAPaper.Having a solid experience with RIL/Pocket I’ve created a list of suggestions to Marco Arment to implement.1. Some pages stored in InstAPaper have removed essential sections of the text. E.g in many blogs comments are not stored in  InstAPaper. Some pages lost almost all of important links (e.g. http://www.lib.rus.ec/a/32416 -sorry, in Russian). RIL/Pocket has 2 modes to store offline- Web view and Article view. Web View includes all links/images of the original page, but it’s very reliable. Article view suppose to strip unrelated information, but often corrupts the content. I prefer to use offline Web view.InstAPaper should also support offline Web view, in case if stripped view removes important part of content.2.  Black full screen Saving on iPad Safari is very annoying. After user pressed a bookmark, the saving has some delay and then for a few seconds prevents from reading the text.Would be better to show as message on the top part(as in Pocket ). I am surprised, that  a full screen popup was  implemented recently as a desired feature. 3.There are no comments allowed on http://blog.instapaper.com/. I would prefer to post some of these notes as comments on http://blog.instapaper.com/ rather than write them in my blog and then send link to Marco.(I found recommendation how to add support of comments on tumblr at http://www.tumblr.com/help, but then realized that Marko was the lead developer ofTumblr.)4. Also there is no support forum. I understand that maintenance of the forum ican be a hassle, but stackexchange fSome time ago I’ve described the issues that I’ve had since a new version of Read It Later, named Pocket, was introduced.I’ve waited with hope for a new upgrade, but I had a huge disappointment with the latest version 16 June 2012. It didn’t fixed any of the two major problems, that I  experienced since new Pocket was introduced- orums can be referred on  http://www.instapaper.com/main/support page, i.e.http://webapps.stackexchange.com/search?q=Instapaper  or http://apple.stackexchange.com/search?q=Instapaper 5. Tags are more convenient than folders. i.e. an ability for the same article to have more than one tag. Also creating of new folders is not supported offline, which is an annoying limitation.6. I would like to have a narrow list - additionally to existing list modes have a subject only list or subject+site list to show more list items on a screen.7. Limit of 500 offline articles sounds quite big, but my RIL list exceeded 1000, so it could be a issue in the future.8. Search button on iPad version is visible, but doesn’t work- it forces to buy Premium subscription. I think, that it’s not correct. If the button in a paid version is visible and enabled, it should  provide  a working functionality, e.g. search in article names only. And leave full-text search for the premium support.9..Copy URL is an important operation and deserves to be in a first level of Action menu, rather than in Share sub-menu.I’ve also have comment re post http://www.marco.org/2011/04/28/removed-instapaper-free. Marco Arment  explained, why he doesn’t provide free version of Instapaper.  I believe that he is loosing essential part of his customers. When I decided which of iPad application to choose, I’ve selected RIL, because I was able to play with free version, and I liked it. I didn’t have a chance to compare RIL and InstAPaper on iPad, so I’ve bought  RIL pro. For a user there is no point to pay even $3 , if there are similar free product, that user can try and see, is it suitable for him/her.I’ve also played with Readability. It doesn’t have folders or tags(which is very important for me), but nicely supports full text search

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• Escaping Code for Different Shells

  - by Jon Purdy

  Question: What characters do I need to escape in a user-entered string to securely pass it into shells on Windows and Unix? What shell differences and version differences should be taken into account? Can I use printf "%q" somehow, and is that reliable across shells? Backstory (a.k.a. Shameless Self-Promotion): I made a little DSL, the Vision Web Template Language, which allows the user to create templates for X(HT)ML documents and fragments, then automatically fill them in with content. It's designed to separate template logic from dynamic content generation, in the same way that CSS is used to separate markup from presentation. In order to generate dynamic content, a Vision script must defer to a program written in a language that can handle the generation logic, such as Perl or Python. (Aside: using PHP is also possible, but Vision is intended to solve some of the very problems that PHP perpetuates.) In order to do this, the script makes use of the @system directive, which executes a shell command and expands to its output. (Platform-specific generation can be handled using @unix or @windows, which only expand on the proper platform.) The problem is obvious, I should think: test.htm: <!-- ... --> <form action="login.vis" method="POST"> <input type="text" name="USERNAME"/> <input type="password" name="PASSWORD"/> </form> <!-- ... --> login.vis: #!/usr/bin/vision # Think USERNAME = ";rm -f;" @system './login.pl' { USERNAME; PASSWORD } One way to safeguard against this kind of attack is to set proper permissions on scripts and directories, but Web developers may not always set things up correctly, and the naive developer should get just as much security as the experienced one. The solution, logically, is to include a @quote directive that produces a properly escaped string for the current platform. @system './login.pl' { @quote : USERNAME; @quote : PASSWORD } But what should @quote actually do? It needs to be both cross-platform and secure, and I don't want to create terrible problems with a naive implementation. Any thoughts?

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• Java getInputStreat SocketTimeoutException instead of NoRouteToHostException

  - by Jon

  I have an odd issue happening when trying to open multiple Input Streams (in separate threads) on Linux (RHEL). The behaviour works as expected on windows. I am kicking off 3 threads to open https connections to 3 different servers. All three are invalid IP addresses (in this test case), so I expect an NoRouteToHostException for each of them. The first two return these as expected, and quite quickly. (see stack trace below) However the third (and 4th when I tested it that way) do NOT give a no route exception. They wait for ages, and then give a SocketTimeoutException (see other stack trace below). This takes ages to come back, and does not accurately express the connection issue. The offending line of code is: reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); Has anyone seen something like this before? Are there multi-threading issues with sockets on REHL or some limit somewhere to how many can connect at once...or...something? Expected stack trace, as received for first two: java.net.NoRouteToHostException: No route to host at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:529) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:559) at sun.net.NetworkClient.doConnect(NetworkClient.java:158) at sun.net.www.http.HttpClient.openServer(HttpClient.java:394) at sun.net.www.http.HttpClient.openServer(HttpClient.java:529) at sun.net.www.protocol.https.HttpsClient.(HttpsClient.java:272) at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:329) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:172) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:916) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:158) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1177) at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:234) Unexpected stack trace, as received on 3rd: java.net.SocketTimeoutException: connect timed out at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:529) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:559) at sun.net.NetworkClient.doConnect(NetworkClient.java:158) at sun.net.www.http.HttpClient.openServer(HttpClient.java:394) at sun.net.www.http.HttpClient.openServer(HttpClient.java:529) at sun.net.www.protocol.https.HttpsClient.(HttpsClient.java:272) at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:329) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:172) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:916) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:158) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1177) at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:234)

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• What is your best example of a violation of the Single Responsibility Principle?

  - by Jon Kruger

  I'm looking for some good examples of code that violates the Single Responsibility Principle. Don't show me any examples from Uncle Bob's books or web sites since those are plastered all over the internet, like this one: interface Modem { public void dial(String pno); public void hangup(); public void send(char c); public char recv(); }

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• PHP DOMDocument Error Handling Problem

  - by Jon

  I'm having trouble trying to write an if statement for DOM that will check if $html is blank. However whenever the html page does end up blank, it just removes everything that would be below DOM (including what I had to check if it was blank). $html = file_get_contents("http://example.com/"); $dom = new DOMDocument; @$dom->loadHTML($html); $links = $dom->getElementById('dividhere')->getElementsByTagName('img'); foreach ($links as $link) { echo $link->getAttribute('src'); } All this does is grab an image url in the specified div, which works perfectly until the page is a blank html page. I've tried using SimpleHTMLDOM, which didn't work either (it didn't even fetch the image on working pages). Did I happen to miss something with this one or am I just missing something in both? include_once('simple_html_dom.php') $html = file_get_html("http://example.com/"); foreach($html->find('div[id="dividhere"]') as $div) { if(empty($div->src)) { continue; } echo $div->src; }

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• Setting a Forms Authentication cookie from a .NET client application

  - by Jon DellOro

  We currently have a .NET 2.0 web app that uses forms authentication via cookies. Associated with this web app is an old VB6 client application that has its own login system. Currently, the users have to login to the VB6 app, and then when they click on a link, need to authenticate themselves again with the .NET forms authentication system. I'm wondering if it's possible to create a client side .NET application, give it the username and password, and set the forms authentication cookie (without the browser being opened). Is that possible??

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• Implementing a robust async stream reader for a console

  - by Jon

  I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. Edit: There are comments below correctly stating that since the data is coming from a stream, there is absolutely nothing that the receiver can infer about the structure of the data unless it is fully prepared to parse it. What I am trying to do here is leverage the "flush the output" "structure" that the owner of the console imparts while writing on it. I am prepared to assume (better: allow my caller to have the option to assume) that the OS will pass me the data written between two flushes of the stream in exactly one piece. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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• Switch statements: do you need the last break? (Javascript mainly)

  - by Jon Raasch

  When using a switch() statement, you add break; in between separate case: declarations. But what about the last one? Normally I just leave it off, but I'm wondering if this has some performance implication I'm not thinking about? I've been wondering about this for a while and don't see it asked elsewhere on Stack-O, but sorry if I missed it. I'm mainly asking this question regarding Javascript, although I'm guessing the answer will apply to all switch() statements.

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• What is the best URL strategy to handle multiple search parameters and operators?

  - by Jon Winstanley

  Searching with mutltiple Parameters In my app I would like to allow the user to do complex searches based on several parameters, using a simple syntax similar to the GMail functionality when a user can search for "in:inbox is:unread" etc. However, GMail does a POST with this information and I would like the form to be a GET so that the information is in the URL of the search results page. Therefore I need the parameters to be formatted in the URL. Requirements: Keep the URL as clean as possible Avoid the use of invalid URL chars such as square brackets Allow lots of search functionality Have the ability to add more functions later. I know StackOverflow allows the user to search by multiple tags in this way: http://stackoverflow.com/questions/tagged/c+sql However, I'd like to also allow users to search with multiple additional parameters. Initial Design My design is currently to do use URLs such as these: http://example.com/search/tagged/c+sql/searchterm/transactions http://example.com/search/searchterm/transactions http://example.com/search/tagged/c+sql http://example.com/search/tagged/c+sql/not-tagged/java http://example.com/search/tagged/c+sql/created/yesterday http://example.com/search/created_by/user1234 I intend to parse the URL after the search parameter, then decide how to construct my search query. Has anyone seen URL parameters like this implemented well on a website? If so, which do it best?

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