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  • Manual Linq to SQL entity framework mapping

    - by kprobst
    I've been playing with the O/R designer in VS and I was wondering if someone could shed come light on this. I'm used to OR mappers that are largely manual (homegrown and e.g., NHibernate). I don't mind encoding the entity classes myself, since they don't change all that often to begin with, and I have this irrational fear of designers and auto generated code as it is. I have noticed that the generated entity classes contain a lot of boilerplate extensibility methods, e.g. On[Property]Changed() and so on where [Property] is a mapped member of the class. These are placed in the setters of the property accessors. I assume it's OK if I don't include these when I do my hand coding, correct? They would be nice if I needed some sort of interception pattern but that's certainly not the case. I guess I just need to know if any of those methods are required by the entity framework to keep track of changes to the mapping types in order for things to work when updating the database. Thanks!

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  • Wouldn't it be nice to have a type variable referring to the class's instance.

    - by user93197
    I often have a pattern like this: class VectorBase<SubClass, Element> where SubClass : VectorBase<SubClass, Element>, new() where Element : Addable<Element> { Element[] data; public VectorBase(Element[] data) { this.data = data; } public SubClass add(SubClass second) { Element[] newData = new Element[data.Length]; for (int i = 0; i < newData.Length; i++) { newData[i] = data[i].add(second.data[i]); } SubClass result = new SubClass(); result.data = newData; return result; } } class VectorInt : VectorBase<VectorInt, Int32> { } class MyInt : Addable<MyInt> { int data; public MyInt(int data) { this.data = data; } public MyInt add(MyInt t) { return new MyInt(data + t.data); } } interface Addable<T> { T add(T t); } But I would rather just have: class VectorBase2<Element> where Element : Addable<Element> { Element[] data; public VectorBase(Element[] data) { this.data = data; } public SubClass add(SubClass second) { Element[] newData = new Element[data.Length]; for (int i = 0; i < newData.Length; i++) { newData[i] = data[i].add(second.data[i]); } SubClass result = new SubClass(data); return result; } } class VectorInt2 : VectorBase2<Int32> { } Why not make the subclass type available to all classes? Is this technically impossible?

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  • shell script segment to avoid overwriting files

    - by johndashen
    I have a perl script (or any executable) E which will take a file foo.xml and write a file foo.txt. I use a Beowulf cluster to run E for a large number of XML files, but I'd like to write a simple job server script in shell (bash) which doesn't overwrite existing txt files. I'm currently doing something like #!/bin/sh PATTERN="[A-Z]*0[1-2][a-j]"; # this matches foo in all cases todo=`ls *.xml | grep $PATTERN`; isdone=`ls *.foo | grep $PATTERN`; whatsleft=todo - isdone; # what's the unix magic? #and then call the job server; jobserve E "$whatsleft"; and then I don't know how to get the difference between $todo and $isdone. I'd prefer using sort/uniq to something like a for loop with grep inside, but I'm not sure how to do it (pipes? temporary files?) As a bonus question, is there a way to do lookahead search in bash grep?

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  • Pick up relevant information from a string using regular expression C#3.0

    - by Newbie
    Hi, I have a situation. I have been given some file name which can be like <filename>YYYYMMDD<fileextension> some valid file names that will satisfy the above pattern are as under xxx20100326.xls, xxx2v20100326.csv, x_20100326.xls, xy2z_abc_20100326_xyz.csv, abc.xyz.20100326.doc, ab2.v.20100326.doc, abc.v.20100326_xyz.xls In what ever be the above defined case, I need to pick up the dates only. So for all the cases, the output will be 20100326. I am trying to achieve the same but no luck. Here is what I have done so far string testdata = "x2v20100326.csv"; string strYYYY = @"\d{4}"; string strMM = @"(1[0-2]|0[1-9])"; string strDD = @"(3[0-1]|[1-2][0-9]|0[1-9])"; string regExPattern = @"\A" + strYYYY + strMM + strDD + @"\Z"; Regex regex = new Regex(regExPattern); Match match = regex.Match(testdata); if (match.Success) { string result = match.Groups[0].Value; } I am using c#3.0 and dotnet framework 3.5 Please help. It is very urgent Thanks in advance.

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  • Spring security or BCrypt algorithm which one is good for accounts like project?

    - by Ranjith Kumar Nethaji
    I am using spring security for hashing my password.And is it safe ,because am using spring security for first time. my code here <security:http auto-config="true"> <security:intercept-url pattern="/welcome*" access="ROLE_USER" /> <security:form-login login-page="/login" default-target-url="/welcome" authentication-failure-url="/loginfailed" /> <security:logout logout-success-url="/logout" /> </security:http> authentication-failure-url="/loginfailed" /> <security:logout logout-success-url="/logout" /> </security:http> <authentication-manager> <authentication-provider> <password-encoder hash="sha" /> <user-service> <user name="k" password="7c4a8d09ca3762af61e59520943dc26494f8941b" authorities="ROLE_USER" /> </user-service> </authentication-provider> </authentication-manager> .And I havnt used bcrypt algorithm.what is your feedback for both?any recommendation?

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  • Design patterns for Caching Images in a MVC?

    - by Onema
    Hi, I'm designing an image cache system that will be used in an MVC CMS. The main purpose of the image cacher is to modify images: scale, crop, etc and cache them in the client site. I have created an image cache Model and Mapper that interact with the Database, to keep track of the images and know what kind of actions have been applied to them (scale, crop, etc). In addition to the Model and Mapper I have created a ImageCacher Class that is used by the API to manage the Model and image creation based on arguments passed by the client site, this class creates the images and generates the links to the images for the View. A coworker argued that I need to include the functionality of this last Class inside the Model, as the bulk of the logic should go in the model. I respectfully disagree with him since I feel the model's responsibility is to deal with the information about the images cached at the database level, and the responsibility of the ImageCacher Class is to create the url/image that we will be caching (keeping the single responsibility principle). In addition to this I believe that a model should not have Presentation-related features, like creating or showing images. Does anyone have any insight on this? is there a particular design pattern that would make this division of tasks clear and and the image cacher reusable? Should I add all the logic in the Model? Thank you.

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  • Refactoring. Your way to reduce code complexity of big class with big methods

    - by Andrew Florko
    I have a legacy class that is rahter complex to maintain: class OldClass { method1(arg1, arg2) { ... 200 lines of code ... } method2(arg1) { ... 200 lines of code ... } ... method20(arg1, arg2, arg3) { ... 200 lines of code ... } } methods are huge, unstructured and repetitive (developer loved copy/paste aprroach). I want to split each method into 3-5 small functions, whith one pulic method and several helpers. What will you suggest? Several ideas come to my mind: Add several private helper methods to each method and join them in #region (straight-forward refactoring) Use Command pattern (one command class per OldClass method in a separate file). Create helper static class per method with one public method & several private helper methods. OldClass methods delegate implementation to appropriate static class (very similiar to commands). ? Thank you in advance!

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  • upload file on database through php code

    - by ruhit
    hi all I have made an application to upload files and its workingout well.now I want to upload my files on database and I also want to display the uploaded files names on my listby accessing the database....so kindly help me. my codes are given below- function uploadFile() { global $template; //$this->UM_index = $this->session->getUserId(); switch($_REQUEST['cmd']){ case 'upload': $filename = array(); //set upload directory //$target_path = "F:" . '/uploaded/'; for($i=0;$i<count($_FILES['ad']['name']);$i++){ if($_FILES["ad"]["name"]) { $filename = $_FILES["ad"]["name"][$i]; $source = $_FILES["ad"]["tmp_name"][$i]; $type = $_FILES["ad"]["type"]; $name = explode(".", $filename); $accepted_types = array('text/html','application/zip', 'application/x-zip-compressed', 'multipart/x-zip', 'application/x-compressed'); foreach($accepted_types as $mime_type) { if($mime_type == $type) { $okay = true; break; } } $continue = strtolower($name[1]) == 'zip' ? true : false; if(!$continue) { $message = "The file you are trying to upload is not a .zip file. Please try again."; } $target_path = "F:" . '/uploaded/'.$filename; // change this to the correct site path if(move_uploaded_file($source, $target_path )) { $zip = new ZipArchive(); $x = $zip->open($target_path); if ($x === true) { $zip->extractTo("F:" . '/uploaded/'); // change this to the correct site path $zip->close(); unlink($target_path); } $message = "Your .zip file was uploaded and unpacked."; } else { $message = "There was a problem with the upload. Please try again."; } } } echo "Your .zip file was uploaded and unpacked."; $template->main_content = $template->fetch(TEMPLATE_DIR . 'donna1.html'); break; default: $template->main_content = $template->fetch(TEMPLATE_DIR . 'donna1.html'); //$this->assign_values('cmd','uploads'); $this->assign_values('cmd','upload'); } } my html page is <html> <link href="css/style.css" rel="stylesheet" type="text/css"> <!--<form action="{$path_site}{$index_file}" method="post" enctype="multipart/form-data">--> <form action="index.php?menu=upload_file&cmd=upload" method="post" enctype="multipart/form-data"> <div id="main"> <div id="login"> <br /> <br /> Ad No 1: <input type="file" name="ad[]" id="ad1" size="10" />&nbsp;&nbsp;Image(.zip)<input type="file" name="ad[]" id="ad1" size="10" /> Sponsor By : <input type="text" name="ad3" id="ad1" size="25" /> <br /> <br /> </div> </div> </form> </html>

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  • SQL Standard Regarding Left Outer Join and Where Conditions

    - by Ryan
    I am getting different results based on a filter condition in a query based on where I place the filter condition. My questions are: Is there a technical difference between these queries? Is there anything in the SQL standard that explains the different resultsets in the queries? Given the simplified scenario: --Table: Parent Columns: ID, Name, Description --Table: Child Columns: ID, ParentID, Name, Description --Query 1 SELECT p.ID, p.Name, p.Description, c.ID, c.Name, c.Description FROM Parent p LEFT OUTER JOIN Child c ON (p.ID = c.ParentID) WHERE c.ID IS NULL OR c.Description = 'FilterCondition' --Query 2 SELECT p.ID, p.Name, p.Description, c.ID, c.Name, c.Description FROM Parent p LEFT OUTER JOIN Child c ON (p.ID = c.ParentID AND c.Description = 'FilterCondition') I assumed the queries would return the same resultsets and I was surprised when they didn't. I am using MS SQL2005 and in the actual queries, query 1 returned ~700 rows and query 2 returned ~1100 rows and I couldn't detect a pattern on which rows were returned and which rows were excluded. There were still many rows in query 1 with child rows with data and NULL data. I prefer the style of query 2 (and I think it is more optimal), but I thought the queries would return the same results.

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  • Importing a C DLL's functions into a C++ program

    - by bobobobo
    I have a 3rd party library that's written in C. It exports all of its functions to a DLL. I have the .h file, and I'm trying to load the DLL from my C++ program. The first thing I tried was surrounding the parts where I #include the 3rd party lib in #ifdef __cplusplus extern "C" { #endif and, at the end #ifdef __cplusplus } // extern "C" #endif But the problem there was, all of the DLL file function linkage looked like this in their header files: a_function = (void *)GetProcAddress(dll, "a_function"); While really a_function had type int (*a_function) (int *). Apparently MSVC++ compiler doesn't like this, while MSVC compiler does not seem to mind. So I went through (brutal torture) and fixed them all to the pattern typedef int (*_a_function) (int *); _a_function a_function ; Then, to link it to the DLL code, in main(): a_function = (_a_function)GetProcAddress(dll, "a_function"); This SEEMS to make the compiler MUCH, MUCH happier, but it STILL complains with this final set of 143 errors, each saying for each of the DLL link attempts: error LNK2005: _a_function already defined in main.obj main.obj Multiple symbol definition errors.. sounds like a job for extern! SO I went and made ALL the function pointer declarations as follows: function_pointers.h typedef int (*_a_function) (int *); extern _a_function a_function ; And in a cpp file: function_pointers.cpp #include "function_pointers.h" _a_function a_function ; ALL fine and dandy.. except for linker errors now of the form: error LNK2001: unresolved external symbol _a_function main.obj Main.cpp includes "function_pointers.h", so it should know where to find each of the functions.. I am bamboozled. Does any one have any pointers to get me functional? (Pardon the pun..)

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  • White-box testing in Javascript - how to deal with privacy?

    - by Max Shawabkeh
    I'm writing unit tests for a module in a small Javascript application. In order to keep the interface clean, some of the implementation details are closed over by an anonymous function (the usual JS pattern for privacy). However, while testing I need to access/mock/verify the private parts. Most of the tests I've written previously have been in Python, where there are no real private variables (members, identifiers, whatever you want to call them). One simply suggests privacy via a leading underscore for the users, and freely ignores it while testing the code. In statically typed OO languages I suppose one could make private members accessible to tests by converting them to be protected and subclassing the object to be tested. In Javascript, the latter doesn't apply, while the former seems like bad practice. I could always wall back to black box testing and simply check the final results. It's the simplest and cleanest approach, but unfortunately not really detailed enough for my needs. So, is there a standard way of keeping variables private while still retaining some backdoors for testing in Javascript?

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  • Need an advice for ASP.NET MVC2 Newsletter Project

    - by ck3g
    I'm new in ASP.NET MVC2. But I want to develop a simply Newsletter site. The main problem which stuck me is how correctly use MVC pattern in News details and comments list. For example: I have a NewsController and action Details inside. And two model classes News and Comments. I want show all comments belongs to this News record and textarea for adding new comments. I wand display all this content in /News/Details/ How can i do it? I tried use PartialViews in Details View: one for Adding Comment and another for Comment list. I have passed comment object thorough ViewData["Comment"]. But i have problems with my models (think I cant use two models in View) Again. How can I display Single Post + Comments + add comment view at single page using ASP.NET MVC2? Another Example is stackoverflow.com. Here is an question + answers + write answer. I need same structure

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  • How to determine if a target will be executed?

    - by Scott Langham
    Hi, I'm writing an msbuild file and have something like this: <ValidateDependsOn>$(ValidateDependsOn);ValidateA</ValidateDependsOn> <ValidateDependsOn>$(ValidateDependsOn);ValidateB</ValidateDependsOn> <Target Name="BuildA"> <!-- stuff --> </Target> <Target Name="BuildB"> <!-- stuff --> </Target> <Target Name="ValidateA"> <Error /> <!-- check properties and machine environment are suitable to run BuildA --> </Target> <Target Name="ValidateB"> <Error /> <!-- check properties and machine environment are suitable to run BuildB --> </Target> Builds can take a while. Originally we had the Build steps depending on the Validate steps, but sometimes a validate step wouldn't run until the middle of the build and you would have wasted time getting there. So, we moved the validate steps to the start by using the ValidateDependsOn pattern to insert the targets to run up front. The problem now though is that sometimes during a build BuildB may not actually run, and this means I don't need and in fact, don't want ValidateB to run. Is there any way I can selectively update ValidateDependsOn by conditionally knowing which targets will actually be run? I'm looking for something equivalent to: <ValidateDependsOn Condition="TargetWillRun(BuildB)">$(ValidateDependsOn);ValidateB</ValidateDependsOn>

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  • Implementing a Version check between an Abstract class and it's implementation

    - by Michael Stum
    I have this abstract class and concrete implementation (they are in different assemblies): public abstract class MyAbstractClass { private static readonly int MyAbstractClassVersion = 1; public abstract int ImplementedVersion { get; } protected MyAbstractClass() { CheckVersion(); } private void CheckVersion() { var message = string.Format( "MyAbstractClass implements Version {0}, concrete is Version {1}", RepositoryVersion, ImplementedVersion); if (!MyAbstractClassVersion.Equals(ImplementedVersion)) throw new InvalidOperationException(message); } } public class ConcreteClass : MyAbstractClass { public ConcreteClass() : base() { // ConcreteClass is guaranteed to have // a constructor that calls the base constructor // I just simplified the example } public override int ImplementedVersion { get { return 2; } } } As you see, I call CheckVersion() from the abstract constructor, to get rid of the "virtual member call in base constructor" message, but I am not sure if that's really the way to do it. Sure, it works, but that doesn't mean it will always work, will it? Also, I wonder if I can get the name of the Concrete Type from the CheckVersion() function? I know that adding new abstract members will force an error anyway (System.TypeLoadException) and I'm not sure if I want this type of strict Versioning, but I'm just curious how it would be done properly given only the abstract class and an implementation (I know I could do it by using interfaces and/or a Factory pattern).

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  • What's the best practice for make username check like Twitter ?

    - by Space Cracker
    I develop registration form and it have username field, and it's required to be like twitter username check ( real time check ) .. i already develop as in every textbox key up I use jquery to pass textbox.Text to page that return if is username exist or not as following code : function Check() { var userName = $('#<%= TextBox1.ClientID %>').val(); if (userName.length < 3) { $('#checkUserNameDIV').html("user name must be between 3 and 20"); return; } $('#checkUserNameDIV').html('<img src="loader.gif" />'); //setTimeout("CheckExistance('" + userName + "')", 5000); CheckExistance(userName); } function CheckExistance(userName) { $.get( "JQueryPage.aspx", { name: userName }, function(result) { var msg = ""; if (result == "1") msg = "Not Exist " + '<img src="unOK.gif" />'; else if (result == "0") msg = "Exist" ; else if (result == "error") msg = "Error , try again"; $('#checkUserNameDIV').html(msg); } ); } but i don't know if is it the best way to do that ? specially i do check every keyup .. is there any design pattern for this problem or nay good practice for doing that ?

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  • How to best manage multi-frame MovieClips with classes?

    - by Arms
    After switching to AS3, I've been having a hell of a time figuring out the best way to manage MovieClips that have UI elements spread across multiple frames with a single class. An example that I am working on now is a simple email form. I have a MovieClip with two frames: the 1st frame has the form elements (text inputs, submit button) the 2nd frame has a "thank you" message and a button to go back to the first frame (to send another email) In the library I have linked the MovieClip to a custom class (Emailer). My immediate problem is how do I assign a MouseEvent.CLICK event to the button on the 2nd frame? I should note at this point that I am trying to avoid putting code on the timeline (except for stop() calls). This is how I am 'solving' the problem now: Emailer registers an event listener for a frame change ( addEventListener("frame 2", onFrameChange) ) On the 2nd frame of the MovieClip I am calling dispatchEvent(new Event("frame 2")); (I would prefer to not have this code on the frame, but I don't know what else to do) My two complaints with this method are that, first I have calls to addEventListener spread out across different class methods (I would rather have all UI event listeners registered in one method), and second that I have to dispatch those custom "onFrameChange" events. The second complaint grows exponentially for MovieClips that have more than just 2 frames. My so called solution feels makes me feel dirty and makes my brain hurt. I am looking for any advice on what to do differently. Perhaps there's a design pattern I should be looking at? Should I swallow my pride and write timeline code even though the rest of my application is written in class files (and I abhor the Flash IDE code editor)? I absolutely LOVE the event system, and have no problem coding applications with it, but I feel like I'm stuck thinking in terms of AS2 when working with mutl-frame movieclips and code. Any and all help would be greatly appreciated.

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  • ForEach loop in Mathematica.

    - by dreeves
    I'd like something like this: ForEach[i_, {1,2,3}, Print[i] ] Or, more generally, to destructure arbitrary stuff in the list you're looping over, like: ForEach[{i_, j_}, {{1,10}, {2,20}, {3,30}}, Print[i*j] ] (Meta-question: is that a good way to call a ForEach loop, with the first argument a pattern like that?) ADDED: Some answerers have rightly pointed out that usually you want to use Map or other purely functional constructs and eschew a non-functional programming style where you use side effects. I agree! But here's an example where I think this ForEach construct is supremely useful: Say I have a list of options (rules) that pair symbols with expressions, like attrVals = {a -> 7, b -> 8, c -> 9} Now I want to make a hash table where I do the obvious mapping of those symbols to those numbers. I don't think there's a cleaner way to do that than ForEach[a_ -> v_, attrVals, h[a] = v] ADDED: I just realized that to do ForEach properly, it should support Break[] and Continue[]. I'm not sure how to implement that. Perhaps it will need to somehow be implemented in terms of For, While, or Do since those are the only loop constructs that support Break[] and Continue[]. If anyone interested in this wants to ask about that as a separate question, please do!

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  • Managing a log stream in C++ in a cout-like notation

    - by Andry
    Hello! I have a class in c++ in order to write log files for an application of mine. I have already built the class and it works, it is something like this: class Logger { std::string _filename; public: void print(std::string tobeprinted); } Well, it is intuitive that, in order to print a line in the log file, for an object of Logger, it is simply necessary to do the following: Logger mylogger("myfile.log"); mylogger.print(std::string("This is a log line")); Well. Using a method approach is not the same as using a much better pattern like << is. I would like to do the following: Logger mylogger("myfile.log"); mylogger << "This is a log line"; That's all. I suppose I must overload the << operator... But overloading using this signature (the classic one): ostream& operator<<(ostream& output, const MyObj& o); But I do not have a ostream... So, should I do as follows? Logger& operator<<(Logger& output, const std::string& o); Is this the right way? Thanks

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  • Zend_Router requirements mismatch

    - by elbicho
    Hello you all: I have two routes that match a url with the same apparent pattern, the difference lies in the $actionRoute, this should only be matched if the variable :action on it equals 'myaction'. If I go to /en/mypage/whatever/myaction it goes as expected through $actionRoute. If I go to /en/mypage/whatever/blahblah it gets rejected by $actionRoute and matched by $genRoute. If I go to /en/mypage/whatever it should be matched by $genRoute but it gets matched by $actionRoute instead throwing and exception because the action noactionAction() does not exist. Don't know what I'm doing wrong, I'd appreciate your help. $genRoute = new Zend_Controller_Router_Route( ':lang/mypage/:var1/:var2', array( 'lang' => '', 'module' => 'mymodule', 'controller' => 'index', 'action' => 'index', 'var1' => 'noone', 'var2' => 'no' ), array( 'var1' => '[a-z\-]+?', 'lang' => '(es|en|fr|de){1}' ) ); $actionRoute = new Zend_Controller_Router_Route( ':lang/mypage/:var1/:action', array( 'lang' => '', 'module' => 'mymodule', 'controller' => 'index', 'action' => 'noaction', 'var1' => 'noone', ), array( 'action' => '(myaction)+?', 'var' => '[a-z\-]+?', 'lang' => '(es|en|fr|de){1}', ) ); $router->addRoute('genroute',$genRoute); $router->addRoute('actionroute',$actionRoute);

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  • Is it OK to set state within Event Raising methods?

    - by Greg
    I ran across this pattern in the code of a library I'm using. It sets state within the event raising method, but only if the event is not null. protected virtual void OnMyEvent(EventArgs e) { if(MyEvent != null) { State = "Executing"; // Only sets state if MyEvent != null. MyEvent(this,e); } } Which means that the state is not set when overriding the method: protected override void OnMyEvent(EventArgs e) { base.OnMyEvent(e); Debug.Assert( State == "Executing" ); // This fails } but is only set when handling the event: foo.MyEvent += (o, args) => Debug.Assert(State == "Executing"); // This passes Setting state within the if(MyEvent != null) seems like bad form, but I've checked the Event Design Guidelines and it doesn't mention this. Do you think this code is incorrect? If so, why? (Reference to design guidelines would be helpful). Edit for Context: It's a Control, I'm trying to create subclass of it, and the state that it's setting is calling EnsureChildControls() conditionally based upon there being an event handler. I can call EnsureChildControls() myself, but I consider that something of a hack.

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  • Ways to make (relatively) safe assumptions about the type of concrete subclasses?

    - by Kylotan
    I have an interface (defined as a abstract base class) that looks like this: class AbstractInterface { public: bool IsRelatedTo(const AbstractInterface& other) const = 0; } And I have an implementation of this (constructors etc omitted): class ConcreteThing { public: bool IsRelatedTo(const AbstractInterface& other) const { return m_ImplObject.has_relationship_to(other.m_ImplObject); } private: ImplementationObject m_ImplObject; } The AbstractInterface forms an interface in Project A, and the ConcreteThing lives in Project B as an implementation of that interface. This is so that code in Project A can access data from Project B without having a direct dependency on it - Project B just has to implement the correct interface. Obviously the line in the body of the IsRelatedTo function cannot compile - that instance of ConcreteThing has an m_ImplObject member, but it can't assume that all AbstractInterfaces do, including the other argument. In my system, I can actually assume that all implementations of AbstractInterface are instances of ConcreteThing (or subclasses thereof), but I'd prefer not to be casting the object to the concrete type in order to get at the private member, or encoding that assumption in a way that will crash without a diagnostic later if this assumption ceases to hold true. I cannot modify ImplementationObject, but I can modify AbstractInterface and ConcreteThing. I also cannot use the standard RTTI mechanism for checking a type prior to casting, or use dynamic_cast for a similar purpose. I have a feeling that I might be able to overload IsRelatedTo with a ConcreteThing argument, but I'm not sure how to call it via the base IsRelatedTo(AbstractInterface) method. It wouldn't get called automatically as it's not a strict reimplementation of that method. Is there a pattern for doing what I want here, allowing me to implement the IsRelatedTo function via ImplementationObject::has_relationship_to(ImplementationObject), without risky casts? (Also, I couldn't think of a good question title - please change it if you have a better one.)

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  • Peculiar JRE behaviour running RMI server under load, should I worry?

    - by darri
    I've been developing a minimalistic Java rich client CRUD application framework for the past few years, mostly as a hobby but also actively using it to write applications for my current employer. The framework provides database access to clients either via a local JDBC based connection or a lightweight RMI server. Last night I started a load testing application, which ran 100 headless clients, bombarding the server with requests, each client waiting only 1 - 2 seconds between running simple use cases, consisting of selecting records along with associated detail records from a simple e-store database (Chinook). This morning when I looked at the telemetry results from the server profiling session I noticed something which to me seemed strange (and made me keep the setup running for the remainder of the day), I don't really know what conclusions to draw from it. Here are the results: Memory GC activity Threads CPU load Interesting, right? So the question is, is this normal or erratic? Is this simply the JRE (1.6.0_03 on Windows XP) doing it's thing (perhaps related to the JRE configuration) or is my framework design somehow causing this? Running the server against MySQL as opposed to an embedded H2 database does not affect the pattern. I am leaving out the details of my server design, but I'll be happy to elaborate if this behaviour is deemed erratic.

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  • What to throw in a C++ class wrapping a C library ?

    - by ereOn
    I have to create a set of wrapping C++ classes around an existing C library. For many objects of the C library, the construction is done by calling something like britney_spears* create_britney_spears() and the opposite function void free_britney_spears(britney_spears* brit). If the allocation of a britney_spears fails, create_britney_spears() returns NULL. This is, as far as I know, a very common pattern. Now I want to wrap this inside a C++ class. //britney_spears.hpp class BritneySpears { public: BritneySpears(); private: boost::shared_ptr<britney_spears> m_britney_spears; }; And here is the implementation: // britney_spears.cpp BritneySpears::BritneySpears() : m_britney_spears(create_britney_spears(), free_britney_spears) { if (!m_britney_spears) { // Here I should throw something to abort the construction, but what ??! } } So the question is in the code sample: What should I throw to abort the constructor ? I know I can throw almost anything, but I want to know what is usually done. I have no other information about why the allocation failed. Should I create my own exception class ? Is there a std exception for such cases ? Many thanks.

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  • Call from a singleton class to a function which in turn calls that class's method

    - by dare2be
    Hello, I am still looking for a way to phrase it properly (I'm not a native speaker...). So I have this class SQL which implements the singleton pattern (for obvious reasons) and I also have this function, checkUsr(), which queries the database using one of SQL's methods. Everything works fine as long as I don't call checkUsr() from within the SQL class. When I do so, the scripts just exits and a blank page is displayed - no errors are returned, no exception is thrown... What's happening? And how do I work around this problem? EDIT: class SQL { public static function singleton() { static $instance; if(!isset($instance)) $instance = new SQL; return $instance; } public function tryLoginAuthor( $login, $sha1 ) { (...) } } function checkUsr() { if (!isset($_SESSION['login']) || !isset($_SESSION['sha1'])) throw new Exception('Not logged in', 1); $SQL = SQL::singleton(); $res = $SQL->tryLoginAuthor($_SESSION['login'], $_SESSION['sha1']); if (!isset($res[0])) throw new Exception('Not logged in', 1); }

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  • Git + SoA, one repo or many?

    - by parsenome
    Normally, when I start up a new application, I'd create a new git repository for it. That's well accepted and plays nice with Github when I want to share my code. At work, I'm working in a service oriented architecture. One very common pattern is to add some code to two different applications at the same time - perhaps adding a model with a RESTful interface to one and a web frontend for managing it on another. Using separate git repositories has some warts in this case. Here are what I see as the downsides of doing separate repositories: I have to commit twice I can't correllate related commits very well No single place to go back and trace history - I'd love to be able to bring up all my commits for the day in a single place Forgetting to pull one repo or another is a gotcha On the other hand, I've used perforce a lot and its one giant repository model has lots of warts too. Perforce has features designed to let help you with those, git doesn't. Has anyone else run into this situation? How did you handle it? What worked well, and what didn't?

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