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  • Decorator Pattern on List<T> for DataGridView

    - by elector
    Hi all, I would like to apply a Decorator on List class and be able to bind it to the WinForms DataGirdView. I would like to know what members of List i need to implement for this new class to be able to bind it to DataGrid. Some of the methods from List I would hide with my decorated class methods and others I would just call _decoratedList.Method(). Is this an option for implementing Decorator on List type? Decorator: public class MyCustomList : List<MyObject> { List<MyObject> _decoratedList; . . . }

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  • Trouble implementing Singleton pattern in Tomcat web application due to Class Loader

    - by jwegan
    I'm trying to implement a Singleton in Tomcat 6.24 on Linux with x86_64 OpenJDK 1.6. My application is just a bunch of JSPs and some static content and the JSPs make calls to my Java code. Currently the web.xml just looks like this: <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <description> App Name </description> <display-name>App Name</display-name> <!-- The Usual Welcome File List --> <welcome-file-list> <welcome-file>pages/index.jsp</welcome-file> </welcome-file-list> </web-app> Before when I was trying to load my Singleton it was getting instantiated twice since the class was getting loaded by two different class loaders (I'm not sure why) and each loader would create an instance of the singleton which is not acceptable for my application. I finally figured out if I exported my code as a jar and put it in $CATALINA_HOME/lib then there was only one instance, but this is not an elegant solution. I've been googling for hours, but I haven't come up with anything yet. I'm wondering if there is some other solution. Currently I'm not precompling my JSPs, could this be part of the problem? Could I write a servlet to ensure the singleton is created? If so how do I do that?

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  • Pattern Matching in Columns

    - by Chronicles
    File 1 A11;F1;BMW A23;F2;BMW B12;F3;BMW H11;F4;JBW File 2 P01;A1;0;0--00 ;123;456;150 P01;A11;0;0--00 ;123;444;208 P01;B12;0;0--00 ;123;111;36 P01;V11;0;0--00 ;123;787;33.9 Output -;-;-;P01;A1;0;0--00 ;123;456;150 A11;F1;BMW;P01;A11;0;0--00 ;123;444;208 B12;F3;BMW;P01;B12;0;0--00 ;123;111;36 -;-;-;P01;V11;0;0--00 ;123;787;33.9 I TRIED awk 'FNR==NR {a[$2] = $0; next }{ if($1 in a) {p=$1;$1="";print a[p],$0}}' File1 File2 But didnt work. Basically I want to get the details from FILE 1 and compare with FILE2 (master list) . Example : A1 in FILE2 was not available in FILE1 , so in output file we have “-“ for 1st three fields and rest from FILE2 . Now, we have A11 and we got the detail in FILE1. So we write details of A11 from both File 1 & 2

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  • C#: Preferred pattern for functions requiring arguments that implement two interfaces

    - by JS Bangs
    The argument to my function f() must implement two different interfaces that are not related to each other by inheritance, IFoo and IBar. I know of two different ways of doing this. The first is to declare an empty interface that inherits from both: public interface IFooBar : IFoo, IBar { // nothing to see here } public int f(IFooBar arg) { // etc. } This, of course, requires that the classes declare themselves as implementing IFooBar rather than IFoo and IBar separately. The second way is to make f() generic with a constraint: public int f<T>(T arg) where T : IFoo, IBar { // etc. } Which of these do you prefer, and why? Are there any non-obvious advantages or disadvantages to each?

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  • Is there a pattern for initializing objects created wth a DI container

    - by Igor Zevaka
    I am trying to get Unity to manage the creation of my objects and I want to have some initialization parameters that are not known until run-time: At the moment the only way I could think of the way to do it is to have an Init method on the interface. interface IMyIntf { void Initialize(string runTimeParam); string RunTimeParam { get; } } Then to use it (in Unity) I would do this: var IMyIntf = unityContainer.Resolve<IMyIntf>(); IMyIntf.Initialize("somevalue"); In this scenario runTimeParam param is determined at run-time based on user input. The trivial case here simply returns the value of runTimeParam but in reality the parameter will be something like file name and initialize method will do something with the file. This creates a number of issues, namely that the Initialize method is available on the interface and can be called multiple times. Setting a flag in the implementation and throwing exception on repeated call to Initialize seems way clunky. At the point where I resolve my interface I don't want to know anything about the implementation of IMyIntf. What I do want, though, is the knowledge that this interface needs certain one time initialization parameters. Is there a way to somehow annotate(attributes?) the interface with this information and pass those to framework when the object is created? Edit: Described the interface a bit more.

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  • parse part of the text from regex pattern

    - by dalco
    I have a string: [\n['-','some text what\rcontains\nnewlines'],\n\n trying to parse: Regex.Split(@"[\n['-','some text what contains newlines'],\n\n", @"\[\n\['(.*)','(.*)'],.*"); but the split return array seems to be null i need to get part of text: "some text what contains newlines"

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  • Canonical pattern reference in Actors programming model.

    - by Bubba88
    Hello! Is there a source, which I could use to learn some of the most used and popular practices regarding Actor-/Agent-oriented programming. My primary concern is about parallelism and distribution limited to the mentioned scheme - Actors, message passing. Should I begin with Erlang documentation or maybe there is any kind of book that describes the most important building blocks when programming Actor-oriented? Thank you! (Most useful examples would be in Scala or F#)

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  • Can't declare unused exception variable when using catch-all pattern

    - by b0x0rz
    what is a best practice in cases such as this one: try { // do something } catch (SpecificException ex) { Response.Redirect("~/InformUserAboutAn/InternalException/"); } the warning i get is that ex is never used. however all i need here is to inform the user, so i don't have a need for it. do i just do: try { // do something } catch { Response.Redirect("~/InformUserAboutAn/InternalException/"); } somehow i don't like that, seems strange!!? any tips? best practices? what would be the way to handle this. thnx

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  • Client-server synchronization pattern / algorithm?

    - by tm_lv
    I have a feeling that there must be client-server synchronization patterns out there. But i totally failed to google up one. Situation is quite simple - server is the central node, that multiple clients connect to and manipulate same data. Data can be split in atoms, in case of conflict, whatever is on server, has priority (to avoid getting user into conflict solving). Partial synchronization is preferred due to potentially large amounts of data. Are there any patterns / good practices for such situation, or if you don't know of any - what would be your approach? Below is how i now think to solve it: Parallel to data, a modification journal will be held, having all transactions timestamped. When client connects, it receives all changes since last check, in consolidated form (server goes through lists and removes additions that are followed by deletions, merges updates for each atom, etc.). Et voila, we are up to date. Alternative would be keeping modification date for each record, and instead of performing data deletes, just mark them as deleted. Any thoughts?

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  • .NET Deployment of Interface/Classes for Command Pattern Question

    - by Jonno
    In theory I would like to produce 2 projects: 1) Asp.net (Sever A) 2) DAL running (Server B) I would like to utilise command objects to comunicate with the DAL. ASP.net instantiates a command class e.g. CmdGetAllUsers which impliments IMyCommand interface and sends it to the DAL (using ASMX or WCF). My question is: Would the class definition of CmdGetAllUsers need to exist on the DAL server? Or would having the interface definition be enough? My goal is to reduce the need to redeploy the DAL code, and have it as a fairly simple pass-through layer. Many thanks for your time.

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  • Override Maven's default resource filter replacement pattern.

    - by Matt Campbell
    By default maven will filter resources like this: <properties> <replace.me>value</replace.me> </properties> <some-tag> <key>${replace.me}</key> </some-tag> will get you: <some-tag> <key>value</key> </some-tag> Is there a way to override the way maven selects the strings to replace? Specifically, I want to be able to use this: <some-tag> <key>@replace.me@</key> </some-tag> to get the same result as above.

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  • Count subset of binary pattern ..

    - by mr.bio
    Hi there . I have a A=set of strings and a B=seperate string. I want to count the number of occurences in from B in A. Example : A: 10001 10011 11000 10010 10101 B: 10001 result would be 3.(10001 is a subset of 10001,10011,10101) So i need a function that takes a set and string and returns an int. int myfunc(set<string> , string){ int result; // My Brain is melting return result ; }

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  • Javascript Regex multiple group matches in pattern

    - by mummybot
    I have a question for a Javascript regex ninja: How could I simplify my variable creation from a string using regex? I currently have it working without using any grouping, but I would love to see a better way! The string is: var url = 'resources/css/main.css?detect=#information{width:300px;}'; The code that works is: var styleStr = /[^=]+$/.exec(url).toString(); var id = /[^\#][^\{]+/.exec(styleStr).toString(); var property = /[^\{]+/.exec(/[^\#\w][^\:]+/.exec(styleStr)).toString(); var value = /[^\:]+/.exec(/[^\#\w\{][^\:]+[^\;\}]/.exec(styleStr)).toString(); This gives: alert(id) //information alert(property) //width alert(value) //300px Any takers?

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  • The simplest concurrency pattern

    - by Ilya Kogan
    Please, would you help me in reminding me of one of the simplest parallel programming techniques. How do I do the following in C#: Initial state: semaphore counter = 0 Thread 1: // Block until semaphore is signalled semaphore.Wait(); // wait until semaphore counter is 1 Thread 2: // Allow thread 1 to run: semaphore.Signal(); // increments from 0 to 1 It's not a mutex because there is no critical section, or rather you can say there is an infinite critical section. So what is it?

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  • Storing millions of URLs in a database for fast pattern matching

    - by Paras Chopra
    I am developing a web analytics kind of system which needs to log referring URL, landing page URL and search keywords for every visitor on the website. What I want to do with this collected data is to allow end-user to query the data such as "Show me all visitors who came from Bing.com searching for phrase that contains 'red shoes'" or "Show me all visitors who landed on URL that contained 'campaign=twitter_ad'", etc. Because this system will be used on many big websites, the amount of data that needs to log will grow really, really fast. So, my question: a) what would be the best strategy for logging so that scaling the system doesn't become a pain; b) how to use that architecture for rapid querying of arbitrary requests? Is there a special method of storing URLs so that querying them gets faster? In addition to MySQL database that I use, I am exploring (and open to) other alternatives better suited for this task.

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  • small scale web site - global javascript file style/format/pattern - improving maintainability

    - by yaya3
    I frequently create (and inherit) small to medium websites where I have the following sort of code in a single file (normally named global.js or application.js or projectname.js). If functions get big, I normally put them in a seperate file, and call them at the bottom of the file below in the $(document).ready() section. If I have a few functions that are unique to certain pages, I normally have another switch statement for the body class inside the $(document).ready() section. How could I restructure this code to make it more maintainable? Note: I am less interested in the functions innards, more so the structure, and how different types of functions should be dealt with. I've also posted the code here - http://pastie.org/999932 in case it makes it any easier var ProjectNameEnvironment = {}; function someFunctionUniqueToTheHomepageNotWorthMakingConfigurable () { $('.foo').hide(); $('.bar').click(function(){ $('.foo').show(); }); } function functionThatIsWorthMakingConfigurable(config) { var foo = config.foo || 700; var bar = 200; return foo * bar; } function globallyRequiredJqueryPluginTrigger (tooltip_string) { var tooltipTrigger = $(tooltip_string); tooltipTrigger.tooltip({ showURL: false ... }); } function minorUtilityOneLiner (selector) { $(selector).find('li:even').not('li ul li').addClass('even'); } var Lightbox = {}; Lightbox.setup = function(){ $('li#foo a').attr('href','#alpha'); $('li#bar a').attr('href','#beta'); } Lightbox.init = function (config){ if (typeof $.fn.fancybox =='function') { Lightbox.setup(); var fade_in_speed = config.fade_in_speed || 1000; var frame_height = config.frame_height || 1700; $(config.selector).fancybox({ frameHeight : frame_height, callbackOnShow: function() { var content_to_load = config.content_to_load; ... }, callbackOnClose : function(){ $('body').height($('body').height()); } }); } else { if (ProjectNameEnvironment.debug) { alert('the fancybox plugin has not been loaded'); } } } // ---------- order of execution ----------- $(document).ready(function () { urls = urlConfig(); (function globalFunctions() { $('.tooltip-trigger').each(function(){ globallyRequiredJqueryPluginTrigger(this); }); minorUtilityOneLiner('ul.foo') Lightbox.init({ selector : 'a#a-lightbox-trigger-js', ... }); Lightbox.init({ selector : 'a#another-lightbox-trigger-js', ... }); })(); if ( $('body').attr('id') == 'home-page' ) { (function homeFunctions() { someFunctionUniqueToTheHomepageNotWorthMakingConfigurable (); })(); } });

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  • Removing a pattern from the beggining and end of a string in ruby

    - by seaneshbaugh
    So I found myself needing to remove <br /> tags from the beginning and end of strings in a project I'm working on. I made a quick little method that does what I need it to do but I'm not convinced it's the best way to go about doing this sort of thing. I suspect there's probably a handy regular expression I can use to do it in only a couple of lines. Here's what I got: def remove_breaks(text) if text != nil and text != "" text.strip! index = text.rindex("<br />") while index != nil and index == text.length - 6 text = text[0, text.length - 6] text.strip! index = text.rindex("<br />") end text.strip! index = text.index("<br />") while index != nil and index == 0 text = test[6, text.length] text.strip! index = text.index("<br />") end end return text end Now the "<br />" could really be anything, and it'd probably be more useful to make a general use function that takes as an argument the string that needs to be stripped from the beginning and end. I'm open to any suggestions on how to make this cleaner because this just seems like it can be improved.

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  • MSMQ - Message Queue Abstraction and Pattern

    - by Maxim Gershkovich
    Hi All, Let me define the problem first and why a messagequeue has been chosen. I have a datalayer that will be transactional and EXTREMELY insert heavy and rather then attempt to deal with these issues when they occur I am hoping to implement my application from the ground up with this in mind. I have decided to tackle this problem by using the Microsoft Message Queue and perform inserts as time permits asynchronously. However I quickly ran into a problem. Certain inserts that I perform may need to be recalled (ie: retrieved) immediately (imagine this is for POS system and what happens if you need to recall the last transaction - one that still hasn’t been inserted). The way I decided to tackle this problem is by abstracting the MessageQueue and combining it in my data access layer thereby creating the illusion of a single set of data being returned to the user of the datalayer (I have considered the other issues that occur in such a scenario (ie: essentially dirty reads and such) and have concluded for my purposes I can control these issues). However this is where things get a little nasty... I’ve worked out how to get the messages back and such (trivial enough problem) but where I am stuck is; how do I create a generic (or at least somewhat generic) way of querying my message queue? One where I can minimize the duplication between the SQL queries and MessageQueue queries. I have considered using LINQ (but have very limited understanding of the technology) and have also attempted an implementation with Predicates which so far is pretty smelly. Are there any patterns for such a problem that I can utilize? Am I going about this the wrong way? Does anyone have an of their own ideas about how I can tackle this problem? Does anyone even understand what I am talking about? :-) Any and ALL input would be highly appreciated and seriously considered… Thanks again.

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  • C++ CRTP(template pattern) question

    - by aaa
    following piece of code does not compile, the problem is in T::rank not be inaccessible (I think) or uninitialized in parent template. Can you tell me exactly what the problem is? is passing rank explicitly the only way? or is there a way to query tensor class directly? Thank you #include <boost/utility/enable_if.hpp> template<class T, // size_t N, class enable = void> struct tensor_operator; // template<class T, size_t N> template<class T> struct tensor_operator<T, typename boost::enable_if_c< T::rank == 4>::type > { tensor_operator(T &tensor) : tensor_(tensor) {} T& operator()(int i,int j,int k,int l) { return tensor_.layout.element_at(i, j, k, l); } T &tensor_; }; template<size_t N, typename T = double> // struct tensor : tensor_operator<tensor<N,T>, N> { struct tensor : tensor_operator<tensor<N,T> > { static const size_t rank = N; }; I know the workaround, however am interested in mechanics of template instantiation for self-education

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