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Articles indexed in May 2010

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  • Is scala functional programming slower than traditional coding?

    - by Fred Haslam
    In one of my first attempts to create functional code, I ran into a performance issue. I started with a common task - multiply the elements of two arrays and sum up the results: var first:Array[Float] ... var second:Array[Float] ... var sum=0f; for(ix<-0 until first.length) sum += first(ix) * second(ix); Here is how I reformed the work: sum = first.zip(second).map{ case (a,b) => a*b }.reduceLeft(_+_) When I benchmarked the two approaches, the second method takes 40 times as long to complete! Why does the second method take so much longer? How can I reform the work to be both speed efficient and use functional programming style?

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  • What are the alternatives for Java authentication?

    - by Crusader
    Preferably something that integrates well with a Flex front end. Yes the Spring Security guys say this is possible, but all examples seem to use legacy jsp tag libraries making them half useless as examples. I don't want to spend a month setting up and learning how to use a security tool. I would like a tool which supports using annotations (@RolesAllowed etc), MINIMAL XML, and 'remember-me' features (not cookie based). Apache Shiro seems to support Flex/Silverlight/Swing as well but I'd like to know if there are any other alternatives that are NOT container specific.

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  • Call a dynamically generated method on a ILGenerator on the same type

    - by Thiado de Arruda
    Normally, when I want to call a dynamic method in another ILGenerator object that is writing a method on the same type I do the following : generator.Emit(OpCodes.Ldarg_0); // reference to the current object generator.Emit(OpCodes.Ldstr, "someArgument"); generator.Emit(OpCodes.Call, methodBuilder); //this methodbuilder is also defined on this dynamic type. However, I faced the following problem: I cant have a reference to the methodbuilder of the method I want to call, because it is generated by another framework(I only get a reference to the current TypeBuilder). This method is defined as protected virtual(and overriden on the methodbuilder I cant get a reference to) in the base class of the current dynamic type and I can get a reference to it by doing this : generator.Emit(OpCodes.Ldarg_0); // reference to the current object generator.Emit(OpCodes.Ldstr, "someArgument"); generator.Emit(OpCodes.Call, baseType.GetMethod("SomeMethodDefinedInBaseClassThatWasOverridenInThisDynamicType")); The problem is that this calls the method on the base type and not the overriden method. Is there any way I can get a reference to a methodbuilder only having a reference to the typebuilder that defined it? Or is there a way to call a method using ILGenerator without having to pass the 'MethodInfo' object to it?

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  • F# return type coercion

    - by Alex
    Hi, In F# I have a function that returns System.Linq.Expression instances: and System.Object with member this.ToExpression() = match this with | :? System.Int32 -> Expression.Constant(this) :> Expression | :? System.Boolean -> Expression.Constant(this) :> Expression | :? Tml.Runtime.Seq as s -> s.ToExpression() | _ -> failwith "bad expression" If I omit the type coercions on the return values F# will infer the return type of the function to ConstantExpression. My first thought was to explicitly mark the return type as being : #Expression, but that didn't work. Is there a more elegant way of doing this that doesn't involve manually casting return types to the most generic type? Thanks.

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  • How to extract terms of specific data constructor from a list in Haskell

    - by finnsson
    A common problem I got in Haskell is to extract all terms in a list belonging to a specific data constructor and I'm wondering if there are any better ways than the way I'm doing it at the moment. Let's say you got data Foo = Bar | Goo , the list foos = [Bar, Goo, Bar, Bar, Goo] and wish to extract all Goos from foos. At the moment I usually do something like goos = [Goo | Goo <- foos] and all is well. The problem is when Goo got a bunch of fields and I'm forced to write something like goos = [Goo a b c d e f | Goo a b c d e f <- foos] which is far from ideal. How you do usually handle this problem?

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  • Turn database result into array

    - by Industrial
    Hi everyone, I have just made the update/add/delete part for the "Closure table" way of organizing query hierarchical data that are shown on page 70 in this slideshare: http://www.slideshare.net/billkarwin/sql-antipatterns-strike-back My database looks like this: Table Categories: ID Name 1 Top value 2 Sub value1 Table CategoryTree: child parent 1 1 2 2 2 1 However, I have a bit of an issue getting the full tree back as an multidimensional array from a single query. Here's what I would like to get back: array ( 'topvalue' = array ( 'Subvalue', 'Subvalue2', 'Subvalue3' = array ('Subvalue 1', 'Subvalue 2', 'Subvalue 3' ) ); ); Update: Found this link, but I still have a hard time to convert it into an array: http://karwin.blogspot.com/2010/03/rendering-trees-with-closure-tables.html

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  • Reading PGP key information

    - by calccrypto
    can someone show a description of the information of what a pgp looks like if only the descriptions were there but not the actual information? something like (i dont remember if the values are correct): packet-type[4 bits], total length in bytes[16 bits], packet version type [4 bits], creation-time[32 bits], encryption-algorithm[8 bits], ...,etc,etc ive tried to understand rfc4880, but its tedious and confusing. so far, i am think i have extracted the 4 i wrote above, but i cant seem to get the rest of the information out. can anyone help? i know i can just find some pgp program, but the whole point of this is to allow me to learn how those programs work in the first place

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  • Opposite of Bloom filter?

    - by abc
    Hi, I'm trying to optimize a piece of software which is basically running millions of tests. These tests are generated in such a way that there can be some repetitions. Of course, I don't want to spend time running tests which I already ran if I can avoid it efficiently. So, I'm thinking about using a Bloom filter to store the tests which have been already ran. However, the Bloom filter errs on the unsafe side for me. It gives false positives. That is, it may report that I've ran a test which I haven't. Although this could be acceptable in the scenario I'm working on, I was wondering if there's an equivalent to a Bloom filter, but erring on the opposite side, that is, only giving false negatives. I've skimmed through the literature without any luck.

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  • How do I serve Ruby on Rails applications on Windows Server 2008?

    - by Adam Lassek
    I have spent the last several hours attempting to get Ruby on Rails running on a Windows server with no luck. At first I tried configuring a test application through IIS7's FastCGI support, but the documentation for this is not very good. I've been following this blog entry, and this one, and this one, and this one but everything seems to be missing major steps, or are out of date. And every article keeps linking back to this Howto from rubyonrails.org that doesn't exist. The sense that I'm getting is that even if I manage to make this work, IIS' FastCGI isn't good enough to use in a production environment anyway. So it looks like my best bet is to setup a reverse proxy in IIS that points to Apache & Mongrel/Passenger using ARR and UrlRewrite. Is there anybody else out there stuck deploying a Rails application on a Windows stack? Am I on the right track? Can you give me a better idea of how to configure this? I believe Plesk already installed an instance of Apache/Tomcat running on this server using a different port, so adding another virtual host shouldn't be difficult; the hardest part seems to be setting up the reverse proxy through IIS.

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  • Problem with PPTP VPN and internet

    - by Enriquev
    Hello, I have an internet connection the following way : Internet Modem <- FireWall(not a router, a firewall) <- PC Everything is setup so my pc has an external ip address, and my firewall takes care of blocking bad stuff. I connect by VPN to an external network, so I added a new connection using Windows Xp's "New connection wizard" (the vpn client that comes with Windows XP), it's a PPTP connection so I used all default settings. I put the PPTP server's IP, my username and password and I succesfully connected. I was able to have access to the external VPN ressources. The only problem is everytime I connect to this VPN, my computer cannot connect to the web anymore, no msn, no ping, no web. Is there anything special I should be doing?

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  • innerText/textContent vs. retrieving each text node

    - by J-P
    I've heard that using el.innerText||el.textContent can yield unreliable results, and that's why I've always insisted on using the following function in the past: function getText(node) { if (node.nodeType === 3) { return node.data; } var txt = ''; if (node = node.firstChild) do { txt += getText(node); } while (node = node.nextSibling); return txt; } This function goes through all nodes within an element and gathers the text of all text nodes, and text within descendants: E.g. <div id="x">foo <em>foo...</em> foo</div> Result: getText(document.getElementById('x')); // => "foo foo... foo" I'm quite sure there are issues with using innerText and textContent, but I've not been able to find a definitive list anywhere and I am starting to wonder if it's just hearsay. Can anyone offer any information about the possibly lacking reliability of textContent/innerText? EDIT: Found this great answer by Kangax -- http://stackoverflow.com/questions/1359469/innertext-works-in-ie-but-not-in-firefox/1359822#1359822

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  • Flex: Method doesn't work when being called on parentDocument

    - by ChrisInCambo
    Hi, I wonder is anyone can look at this code and tell me why calling the removeSelectedChild works when called from the same document, but returns the following error when called from the child document/component. "ArgumentError: Error #2025: The supplied DisplayObject must be a child of the caller." <?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" > <mx:Accordion id="myAccordion" width="100%" height="100%" selectedIndex="0"> <mx:Script> <![CDATA[ public function removeSelectedChild():void { myAccordion.removeChild(myAccordion.selectedChild); } ]]> </mx:Script> <mx:headerRenderer> <mx:Component> <mx:Button click="{ parentDocument.removeSelectedChild() }" /> </mx:Component> </mx:headerRenderer> <mx:HBox> <mx:Button click="{ removeSelectedChild() }" /> </mx:HBox> </mx:Accordion> </mx:Application> Clicking on the button in the child produces the expected result, whilst clicking on the header throws an error despite the fact they both call exactly the same method. Sorry that the example is a little contrived, this problem arose in a quite complicated view, which was using all kinds of custom components. This was the only way I could display it in a way that will be quick for you to compile and easy to focus on the real issue without background noise. I'm pulling my hair out on this one and would really appreciate it if anyone could help. Cheers, Chris

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  • C# calcuate date ranges from a list of dates.

    - by nakulringshia
    Hi Given a list of dates (which may not be sorted), I want to build a list of date ranges - E.g. Assuming MM/DD format, Input - 5/1, 5/5, 5/6, 5/15, 5/7, 5/8, 5/19,5/20, 5/23 Output - Date Range 1: 5/1 to 5/1 Date Range 2: 5/5 to 5/8 Date Range 3: 5/15 to 5/15 Date Range 4: 5/19 to 5/20 Date Range 5: 5/23 to 5/23 Basically, a range should be continuous. Thanks Nakul Ringshia

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  • Jquery doesn't post for some reason

    - by Asaf
    I wrote this small page and for some reason when I cilck on the submit nothing happens (checked on firebug, no submit is happening) <head> <script type="text/javascript" src="jquery-1.4.2.min.js"></script> <script type="text/javascript"> $('form#login').submit(function() { $.ajax({ type: 'POST', url: 'http://my.site/login.php', data: this.html(data), success: success, dataType: dataType }) }); </script> </head> <body> <form action="#" id="login"> <input type="textbox" id="UserName" value="user"> <input type="textbox" id="Password" value="password"> <input type="submit" value="submit"> </form> </body>

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  • Run javascript after form submission in update panel?

    - by AverageJoe719
    This is driving me crazy! I have read at least 5 questions on here closely related to my problem, and probably 5 or so more pages just from googling. I just don't get it. I am trying to have a jqueryui dialog come up after a user fills out a form saying 'registration submitted' and then redirecting to another page, but I cannot for the life of me get any javascript to work, not even a single alert. Here is my update panel: <asp:ScriptManager ID="ScriptManager1" runat="server"> </asp:ScriptManager> <asp:UpdatePanel ID="upForm" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="False"> <ContentTemplate> 'Rest of form' <asp:Button ID="btnSubmit" runat="server" Text="Submit" /> <p>Did register Pass? <%= registrationComplete %></p> </ContentTemplate> </asp:UpdatePanel> The Jquery I want to execute: (Right now this is sitting in the head of the markup, with autoOpen set to false) <script type="text/javascript"> function pageLoad() { $('#registerComplete').dialog({ autoOpen: true, width: 270, resizable: false, modal: true, draggable: false, buttons: { "Ok": function() { window.location.href = "someUrl"; } } }); } </script> Finally my code behind: ( Commented out all the things I've tried) Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnSubmit.Click 'Dim sbScript As New StringBuilder()' registrationComplete = True registrationUpdatePanel.Update() 'sbScript.Append("<script language='JavaScript' type='text/javascript'>" + ControlChars.Lf)' 'sbScript.Append("<!--" + ControlChars.Lf)' 'sbScript.Append("window.location.reload()" + ControlChars.Lf)' 'sbScript.Append("// -->" + ControlChars.Lf)' 'sbScript.Append("</")' 'sbScript.Append("script>" + ControlChars.Lf)' 'ScriptManager.RegisterClientScriptBlock(Me.Page, Me.GetType(), "AutoPostBack", sbScript.ToString(), False)' 'ClientScript.RegisterStartupScript("AutoPostBackScript", sbScript.ToString())' 'Response.Write("<script type='text/javascript'>alert('Test')</script>")' 'Response.Write("<script>windows.location.reload()</script>")' End Sub I've tried: Passing variables from server to client via inline <%= % in the javascript block of the head tag. Putting that same code in a script tag inside the updatePanel. Tried to use RegisterClientScriptBlock and RegisterStartUpScript Just doing a Response.Write with the script tag written in it. Tried various combinations of putting the entire jquery.dialog code in the registerstartup script, or just trying to change the autoOpen property, or just calling "open" on it. I can't even get a simple alert to work with any of these, so I am doing something wrong but I just don't know what it is. Here is what I know: The Jquery is binding properly even on async postbacks, because the div container that is the dialog box is always invisible, I saw a similiar post on here stating that was causing an issue, this isn't the case here. Using page_load instead of document.ready since that is supposed to run on both async and normal postbacks, so that isn't the issue. The update panel is updating correctly because <p>Did register Pass? <%= registrationComplete %></p> updates to true after I submit the form. So how can I make this work? All I want is - click submit button inside an update panel - run server side code to validate form and insert into db - if everything succeeded, have that jquery (modal) dialog pop up saying hey it worked.

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  • Per Application Packet Analyzer

    - by Anindya Chatterjee
    Is there any tool which can analyze network traffic per application? Wireshark does not have per application filtering, fiddler also does not give proper logging for any application. So can anyone please help me out to find an app which can analyze network traffic originating from a random application and log the traffic for that particular application only?

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  • PHP unlink OR rewrite own/current file by itself

    - by Email
    Hi Task: Cut or erase a file after first walk-through. i have an install file called "index.php" which creates another php file. <? /* here some code*/ $fh = fopen($myFile, 'w') or die("can't open file"); $stringData = "<?php \n echo 'hallo, *very very long text*'; \n ?>"; fwrite($fh, $stringData); /*herecut"/ /*here some code */ after the creation of the new file this file is called and i intent to erase the filecreation call since it is very long and only needed on first install. i therefor add to the above code echo 'hallo, *very very long text*'; \n ***$new= file_get_contents('index.php'); \n $findme = 'habanot'; $pos = strpos($new, $findme); if ($pos === false) { $marker='herecut';\n $new=strstr($new,$marker);\n $new='<?php \n /*habanot*/\n'.$new;\n $fh = fopen('index.php', 'w') or die 'cant open file'); $stringData = $new; fwrite($fh, $stringData); fclose($fh);*** ?>"; fwrite($fh, $stringData);]} Isnt there an easier way or a function to modify the current file or even "self destroy" a file after first call? Regards

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  • Resilient Linux Mail Server Setup

    - by Coops
    How would people design a resilient mail server setup with Linux? On an application level what the system needs to provide is both an incoming and outgoing mail service (i.e. SMTP & IMAP), along with filtering and archive storage (the archive part isn't critical yet, so we'll look at this later probably). What is required on top of this is a resilient system, i.e. one which will handle individual server failures without interrupting service. As such I would term this a High Availability mail system. This is in contrast to a High Performance mail setup, as in our case the volume of mail being handled isn't the important factor, it's simply that it stays online. Having not approached this problem before, the first thing I thought of was a clustered file system (gfs/gluster/etc), combined with heartbeat to failover a floating IP to another box in the case of a server failure. Combined with postfix & dovecot does this sound feasible to people?

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  • IQueryable and lazy loading

    - by Nelson
    I'm having a hard time determining the best way to handle this... With Entity Framework (and L2S), LINQ queries return IQueryable. I have read various opinions on whether the DAL/BLL should return IQueryable, IEnumerable or IList. Assuming we go with IList, then the query is run immediately and that control is not passed on to the next layer. This makes it easier to unit test, etc. You lose the ability to refine the query at higher levels, but you could simply create another method that allows you to refine the query and still return IList. And there are many more pros/cons. So far so good. Now comes Entity Framework and lazy loading. I am using POCO objects with proxies in .NET 4/VS 2010. In the presentation layer I do: foreach (Order order in bll.GetOrders()) { foreach (OrderLine orderLine in order.OrderLines) { // Do something } } In this case, GetOrders() returns IList so it executes immediately before returning to the PL. But in the next foreach, you have lazy loading which executes multiple SQL queries as it gets all the OrderLines. So basically, the PL is running SQL queries "on demand" in the wrong layer. Is there any sensible way to avoid this? I could turn lazy loading off, but then what's the point of having this "feature" that everyone was complaining EF1 didn't have? And I'll admit it is very useful in many scenarios. So I see several options: Somehow remove all associations in the entities and add methods to return them. This goes against the default EF behavior/code generation and makes it harder to do some composite (multiple entity) LINQ queries. It seems like a step backwards. I vote no. If we have lazy loading anyway which makes it hard to unit test, then go all the way and return IQueryable. You'll have more control farther up the layers. I still don't think this is a good option because IQueryable ties you to L2S, L2E, or your own full implementation of IQueryable. Lazy loading may run queries "on demand", but doesn't tie you to any specific interface. I vote no. Turn off lazy loading. You'll have to handle your associations manually. This could be with eager loading's .Include(). I vote yes in some specific cases. Keep IList and lazy loading. I vote yes in many cases, only due to the troubles with the others. Any other options or suggestions? I haven't found an option that really convinces me.

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