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  • changing the serialization procedure for a graph of objects (.net framework)

    - by pierusch
    Hello I'm developing a scientific application using .net framework. The application depends heavily upon a large data structure (a tree like structure) that has been serialized using a standard binaryformatter object. The graph structure looks like this: <serializable()>Public class BigObjet inherits list(of smallObject) end class <serializable()>public class smallObject inherits list(of otherSmallerObjects) end class ... The binaryFormatter object does a nice job but it's not optimized at all and the entire data structure reaches around 100Mb on my filesystem. Deserialization works too but it's pretty slow (around 30seconds on my quad core). I've found a nice .dll on codeproject (see "optimizing serialization...") so I wrote a modified version of the classes above overriding the default serialization/deserialization procedure reaching very good results. The problem is this: I can't lose the data previosly serialized with the old version and I'd like to be able to use the new serialization/deserialization method. I have some ideas but I'm pretty sure someone will be able to give me a proper and better advice ! use an "helper" graph of objects who takes care of the entire serialization/deserialization procedure reading data from the old format and converting them into the classes I nedd. This could work but the binaryformatter "needs" to know the types being serialized so........ :( modify the "old" graph to include a modified version of serialization procedure...so I'll be able to deserialize old file and save them with the new format......this doesn't sound too good imho. well any help will be higly highly appreciated :)

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  • NSNotification vs. Delegate Protocols?

    - by jr
    I have an iPhone application which basically is getting information from an API (in XML, but maybe JSON eventually). The result objects are typically displayed in view controllers (tables mainly). Here is the architecture right now. I have NSOperation classes which fetch the different objects from the remote server. Each of these NSOperation classes, will take a custom delegate method which will fire back the resulting objects as they are parsed, and then finally a method when no more results are available. So, the protocol for the delegates will be something like: (void) ObjectTypeResult:(ObjectType *)result; (void) ObjectTypeNoMoreResults; I think the solution works well, but I do end up with a bunch of delegate protocols around and then my view controllers have to implement all these delegate methods. I don't think its that bad, but I'm always on the lookout for a better design. So, I'm thinking about using NSNotifications to remove the use of the delegates. I could include the object in the userInfo part of the notification and just post objects as received, and then a final event when no more are available. Then I could just have one method in each view controller to receive all the data, even when using multiple objects in one controller.† So, can someone share with me some pros/cons of each approach. Should I consider refactoring my code to use Events rather then the delegates? Is one better then the other in certain situations? In my scenario I'm really not looking to receive notifications in multiple places, so maybe the protocol based delegates are the way to go. Thanks!

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  • Dealing With Java Default Level Access Specifiers

    - by Tom Tresansky
    I've seen some code in a project recently where some fields in a couple classes have been using the default access modifier without good reason to. It almost looks like a case of "oops, forgot to make these private". Since the classes are used almost exclusively outside of the package they are defined in, the fields are not visible from the calling code, and are treated as private. So the mistake/oversight would not be very noticeable. However, encapsulation is broken. If I wanted to add a new class to the existing package, I could then mess with internal data in objects using fields with default access. So, my questions: Are there any best practices concerning default access specifiers that I should be aware of? Anything that would help prevent this type of accident from re-occurring? Are are any annotations which might say something to the effect of "I really meant for these to be default access"? Using CheckStyle, or any other Eclipse plugins, is there any way to flag instances of default fields, or disallow any not accompanied by, say, a "//default access" comment trailing them?

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  • Is there a Scala version of .irbrc or another way to define some default libraries for REPL use?

    - by Tom Morris
    I've written a little library that uses implicits to add functionality that one only needs when using the REPL in Scala. Ruby has libraries like this - for things like pretty printing, firing up text editors (like the interactive_editor gem which invokes Vim from irb - see this post), debuggers and the like. The library I am trying to write adds some methods to java.lang.Class and java.lang.reflect classes using the 'pimp my library' implicit conversion process to help you go and find documentation (initially, with Google, then later possibly with a JavaDoc/ScalaDoc viewer, and maybe the StackOverflow API eventually!). It's an itch-scratching library: I spend so much time copying and pasting classnames into Google that I figured I may as well automate the process. It is the sort of functionality that developers will want to add to their system for use only in the REPL - they shouldn't really be adding it to projects (partly because it may not be something that their fellow developers want, but also because if you are doing some exploratory development, it may be with just a Scala REPL that's not being invoked by an IDE or build tool). In my case, I want to include a few classes and set up some implicits - include a .jar on the CLASSPATH and import it, basically. In Ruby, this is the sort of thing that you'd add to your .irbrc file. Other REPLs have similar ways of setting options and importing libraries. Is there a similar file or way of doing this for the Scala REPL?

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  • Memory leaks after using typeinfo::name()

    - by icabod
    I have a program in which, partly for informational logging, I output the names of some classes as they are used (specifically I add an entry to a log saying along the lines of Messages::CSomeClass transmitted to 127.0.0.1). I do this with code similar to the following: std::string getMessageName(void) const { return std::string(typeid(*this).name()); } And yes, before anyone points it out, I realise that the output of typeinfo::name is implementation-specific. According to MSDN The type_info::name member function returns a const char* to a null-terminated string representing the human-readable name of the type. The memory pointed to is cached and should never be directly deallocated. However, when I exit my program in the debugger, any "new" use of typeinfo::name() shows up as a memory leak. If I output the information for 2 classes, I get 2 memory leaks, and so on. This hints that the cached data is never being freed. While this is not a major issue, it looks messy, and after a long debugging session it could easily hide genuine memory leaks. I have looked around and found some useful information (one SO answer gives some interesting information about how typeinfo may be implemented), but I'm wondering if this memory should normally be freed by the system, or if there is something i can do to "not notice" the leaks when debugging. I do have a back-up plan, which is to code the getMessageName method myself and not rely on typeinfo::name, but I'd like to know anyway if there's something I've missed.

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  • JSF 2 - clearing component attributes on page load?

    - by jamiebarrow
    Hi, The real question: Is there a way to clear certain attributes for all components on an initial page load? Background info: In my application, I have a JSF 2.0 frontend layer that speaks to a service layer (the service layer is made up of Spring beans that get injected to the managed beans). The service layer does its own validation, and I do the same validation in the frontend layer using my own validator classes to try and avoid code duplication somehow. These validator classes aren't JSF validators, they're just POJOs. I'm only doing validation on an action, so in the action method, I perform validation, and only if it's valid do I call through to the service layer. When I do my validation, I set the styleClass and title on the UIComponents using reflection (so if the UIComponent has the setStyleClass(:String) or setTitle(:String) methods, then I use them). This works nicely, and on a validation error I see a nicely styled text box with a popup containing the error message if I hover over it. However, since the component is bound to a Session Scoped Managed Bean, it seems that these attributes stick. So if I navigate away and come back to the same page, the styleClass and title are still in the error state. Is there a way to clear the styleClass and title attributes on each initial page load? Thanks, James P.S. I'm using the action method to validate because of some issues I had before with JSF 1.2 and it's validation methods, but can't remember why... so that's why I'm using the action method to validate.

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  • Method having an abstract class as a parameter

    - by Ferhat
    I have an abstract class A, where I have derived the classes B and C. Class A provides an abstract method DoJOB(), which is implemented by both derived classes. There is a class X which has methods inside, which need to call DoJOB(). The class X may not contain any code like B.DoJOB() or C.DoJOB(). Example: public class X { private A foo; public X(A concrete) { foo = concrete; } public FunnyMethod() { foo.DoJOB(); } } While instantiating class X I want to decide which derived class (B or C) must be used. I thought about passing an instance of B or C using the constructor of X. X kewl = new X(new C()); kewl.FunnyMethod(); //calls C.DoJOB() kewl = new X(new B()); kewl.FunnyMethod(); // calls B.DoJOB() My test showed that declaring a method with a parameter A is not working. Am I missing something? How can I implement this correctly? (A is abstract, it cannot be instantiated)

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  • DBIx::Class base result class

    - by Rob
    Hi there, I am trying to create a model for Catalyst by using DBIx::Class::Schema::Loader. I want the result classes to have a base class I can add methods to. So MyTable.pm inherits from Base.pm which inherits from DBIx::Class::core (default). Somehow I cannot figure out how to do this. my create script is below, can anyone tell me what I am doing wrong? The script creates my model ok, but all resultset classes just directly inherit from DBIx::Class::core without my Base class in between. #!/usr/bin/perl use DBIx::Class::Schema::Loader qw/ make_schema_at /; #specifically for the entities many-2-many relation $ENV{DBIC_OVERWRITE_HELPER_METHODS_OK} = 1; make_schema_at( 'MyApp::Schema', { dump_directory => '/tmp', debug => 1, overwrite_modifications => 1, components => ['EncodedColumn'], #encoded password column use_namespaces => 1, default_resultset_class => 'Base' }, [ 'DBI:mysql:database=mydb;host=localhost;port=3306','rob', '******' ], );

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  • MEF Import Composition Issues

    - by Tim
    I've read all the questions I can find regarding the issues of composing imports without exporting the containing class but I can't find a solution to my problem. Does anybody know a way to achieve what I'm trying to do? My module assemblies have forms and classes which they use internally. These forms need access to some of the exported contracts but imports are not loaded as they are not in the MEF 'composition tree' Host assembly: public class Host { public Host() { /* Compose parts here... */ } [Export(typeof(Licence))] public Licence LoadedLicence { get; set; } [Export(typeof(IModule))] public List<IModule> LoadedModules { get; set; } } Module assembly: [Export(typeof(IModule))] public class Module : IModule { public Module() { } public void DoSomething() { SubForm sub = new SubForm(); sub.ShowDialog(); } [Import(typeof(Licence))] public Licence LoadedLicence { get; set; } // This works here } public class SubForm : Form { public SubForm () { } [Import(typeof(Licence))] public Licence LoadedLicence { get; set; } // This doesn't work in here } As far as I can see, my options are: Pass parameters to constructors (pain) Use a dummy export on the classes that need imports satisfying? Any others?

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  • Javascript toggle using custom attributes

    - by Jacob
    Can't seem to get this to work for me, can anyone offer me some help? http://codepen.io/anon/pen/kABjC This should open and close a section of text based on click, it takes the ID # which is just a digit (1,2,3,4,etc) and using that id targets an id to open and close the section. Javascript $(document).ready(function(){ $('.classclick').click(function(){ $('#class'+$(this).Attr('data-id')+"show").show(400); }); }); HTML <div class="classes"> <?php foreach ($classes as $class): ?> <div class="class"> <div class="classclick" data-id="<?=$class['cid']?>"> <div class="class-title"> <?=$class['className']?> </div> <div class="class-intensity"> Intensity: <?=$class['classIntensity']?> </div> </div> <div class="class-show hidden" id="class<?=$class['cid']?>show"> <div class="class-inner-content"> <div class="two-thirds"> <?=$class['classDesc']?> </div> <div class="one-third"> Things To Know: asdfasd asdf afsdadfs fsda dfsa dfsadfsa </div> </div> </div> </div> <?php endforeach; ?> </div>

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  • GWT with JPA - no persistence provider...

    - by meliniak
    GWT with JPA There are two projects in my eclipse workspace, let's name them: -JPAProject -GWTProject JPAProject contains JPA configuration stuff (persistence.xml, entity classes and so on). GWTProject is an examplary GWT project (taken from official GWT tutorial). Both projects work fine alone. That is, I can create EMF (EntityManagerFactory) in JPAProject and get entities from the database. GWTProject works fine too, I can run it, fill the field text in the browser and get the response. My goal is to call JPAProject from GWTProject to get entities. But the problem is that when calling DAO, I get the following exception: [WARN] Server class 'com.emergit.service.dao.profile.ProfileDaoService' could not be found in the web app, but was found on the system classpath [WARN] Adding classpath entry 'file:/home/maliniak/workspace/emergit/build/classes/' to the web app classpath for this session [WARN] /gwttest/greet javax.persistence.PersistenceException: No Persistence provider for EntityManager named emergitPU at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source) at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source) at com.emergit.service.dao.profile.JpaProfileDaoService.<init>(JpaProfileDaoService.java:19) at pl.maliniak.server.GreetingServiceImpl.<init>(GreetingServiceImpl.java:21) . . . at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488) [ERROR] 500 - POST /gwttest/greet (127.0.0.1) 3812 bytes I guess that the warnings at the beginning can be omitted for now. Do you have any ideas? I guess I am missing some basic point. All hints are highly apprecieable.

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  • nth-of-type only working for 1 and 2

    - by Owen O'Neill
    I have a styling problem, I am using WordPress and want to do have the first two classes completely different to the others. My ideal situation is to have: .si-biplace:nth-of-type(3) { float:left; margin:20px 0px 0px 0px; } .si-image:nth-of-type(3) { float:left; margin:20px 0px 0px 0px; border:0px; } .si-title:nth-of-type(3) { width:100px; height:20px; margin:0px; font-size:7px; color:#FFFFFF; font-weight:bold; } They seem to work fine when it is: .si-biplace { float:left; margin:-10px 0px 0px 0px; } .si-biplace:nth-of-type(2) { float:left; margin:-10px 0px 0px 15px; } Is there a reason why it will not work with nth-of-type(3) but will with nth of type 2? I basically want different attributes for every next time the div is used but cannot have separate div classes as it runs through a php array.

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  • No grammar constraints (DTD or XML schema) detected for the document.

    - by fastcodejava
    I have this dtd : http://fast-code.sourceforge.net/template.dtd But when I include in an xml I get the warning : No grammar constraints (DTD or XML schema) detected for the document. The xml is : <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE templates PUBLIC "//UNKNOWN/" "http://fast-code.sourceforge.net/template.dtd"> <templates> <template type="type"> <description>Some</description> <variation></variation> <variation-field></variation-field> <allow-multiple-variation></allow-multiple-variation> <class-pattern></class-pattern> <getter-setter>setter</getter-setter> <allowed-file-extensions>java</allowed-file-extensions> <number-required-classes>1</number-required-classes> <template-body> <![CDATA[ Some Data ]]> </template-body> </template> </templates> Any clue?

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  • Difference between MVC FilterAttribute and Filter

    - by zaaaaphod
    I'm trying to write my own custom AuthorizationAttribute that uses DI. I'm using the MUNQ IoC provider for it's speed and have decided to use constructor injection on all my classes as opposed to post instatiation property binding (because I prefer it). I'm trying to write a custom IFilterProvider that will use my IoC container to return requests for filters (so that I can map concrete classes using the container). I've come up with the following. public class FilterProvider : IFilterProvider { private readonly IocContainer _container; public FilterProvider(IocContainer container) { _container = container; } public IEnumerable<Filter> GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor) { var x = Enumerable.Union<Object>(_container.ResolveAll<IActionFilter>(), _container.ResolveAll<IAuthorizationFilter>()); foreach (Filter actionFilter in x) yield return new Filter(actionFilter, FilterScope.First, null); } } The above code will fail during the foreach because my objects that implement IAuthorizationFilter are based on FilterAttribute and not Filter My question is, what is the difference between Filter and FilterAttribute? I would have thought that there would have been a common link between them, unless I'm missing something. Another deeper question is, how come there is no IFilterAttributeProvider that would support IEnumerable GetFilters(...) Is there some other way that I should be using to resolve IAuthorizationFilter via my IoC container? Thank you very much for your help. Z

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  • How to wrap a C function whose parameters are pointer to structs, so that it can be called from Lua?

    - by pierr
    I have the follwing C function. How should I wrap it so it can be called from a Lua script? typedef struct tagT{ int a ; int b ; } type_t; int lib_a_f_4(type_t *t) { return t->a * t->b ; } I know how to wrapr it if the function parameter type were int or char *. Should I use table type for a C structure? EDIT: I am using SWIG for the wraping , according to this doc, It seems that I should automatically have this funtion new_type_t(2,3) , but it is not the case. If you wrap a C structure, it is also mapped to a Lua userdata. By adding a metatable to the userdata, this provides a very natural interface. For example, struct Point{ int x,y; }; is used as follows: p=example.new_Point() p.x=3 p.y=5 print(p.x,p.y) 3 5 Similar access is provided for unions and the data members of C++ classes. C structures are created using a function new_Point(), but for C++ classes are created using just the name Point().

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  • Measuring how "heavily linked" a node is in a graph

    - by Eduardo León
    I have posted this question at MathOverflow.com as well. I am no mathematician and English is not my first language, so please excuse me if my question is too stupid, it is poorly phrased, or both. I am developing a program that creates timetables. My timetable-creating algorithm, besides creating the timetable, also creates a graph whose nodes represent each class I have already programmed, and whose arcs represent which pairs of classes should not be programmed at the same time, even if they have to be reprogrammed. The more "heavily linked" a node is, the more inflexible its associated class is with respect to being reprogrammed. Sometimes, in the middle of the process, there will be no option but to reprogram a class that has already been programmed. I want my program to be able to choose a class that, if reprogrammed, affects the least possible number of other already-programmed classes. That would mean choosing a node in the graph that is "not very heavily linked", subject to some constraints with respect to which nodes can be chosen. EDIT: The question was... Do you know any algorithm that measures how "heavily linked" a node is?

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  • C++ compiler unable to find function (namespace related)

    - by CS student
    I'm working in Visual Studio 2008 on a C++ programming assignment. We were supplied with files that define the following namespace hierarchy (the names are just for the sake of this post, I know "namespace XYZ-NAMESPACE" is redundant): (MAIN-NAMESPACE){ a bunch of functions/classes I need to implement... (EXCEPTIONS-NAMESPACE){ a bunch of exceptions } (POINTER-COLLECTIONS-NAMESPACE){ Set and LinkedList classes, plus iterators } } The MAIN-NAMESPACE contents are split between a bunch of files, and for some reason which I don't understand the operator<< for both Set and LinkedList is entirely outside of the MAIN-NAMESPACE (but within Set and LinkedList's header file). Here's the Set version: template<typename T> std::ostream& operator<<(std::ostream& os, const MAIN-NAMESPACE::POINTER-COLLECTIONS-NAMESPACE::Set<T>& set) Now here's the problem: I have the following data structure: Set A Set B Set C double num It's defined to be in a class within MAIN-NAMESPACE. When I create an instance of the class, and try to print one of the sets, it tells me that: error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'const MAIN-NAMESPACE::POINTER-COLLECTIONS-NAMESPACE::Set' (or there is no acceptable conversion) However, if I just write a main() function, and create Set A, fill it up, and use the operator- it works. Any idea what is the problem? (note: I tried any combination of using and include I could think of).

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  • JPA: persisting object, parent is ok but child not updated

    - by James.Elsey
    Hello, I have my domain object, Client, I've got a form on my JSP that is pre-populated with its data, I can take in amended values, and persist the object. Client has an abstract entity called MarketResearch, which is then extended by one of three more concrete sub-classes. I have a form to pre-populate some MarketResearch data, but when I make changes and try to persist the Client, it doesn't get saved, can someone give me some pointers on where I've gone wrong? My 3 domain classes are as follows (removed accessors etc) public class Client extends NamedEntity { @OneToOne @JoinColumn(name = "MARKET_RESEARCH_ID") private MarketResearch marketResearch; ... } @Inheritance(strategy = InheritanceType.JOINED) public abstract class MarketResearch extends AbstractEntity { ... } @Entity(name="MARKETRESEARCHLG") public class MarketResearchLocalGovernment extends MarketResearch { @Column(name = "CURRENT_HR_SYSTEM") private String currentHRSystem; ... } This is how I'm persisting public void persistClient(Client client) { if (client.getId() != null) { getJpaTemplate().merge(client); getJpaTemplate().flush(); } else { getJpaTemplate().persist(client); } } To summarize, if I change something on the parent object, it persists, but if I change something on the child object it doesn't. Have I missed something blatantly obvious? Thanks

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  • What's so bad about building XML with string concatenation?

    - by wsanville
    In the thread What’s your favorite “programmer ignorance” pet peeve?, the following answer appears, with a large amount of upvotes: Programmers who build XML using string concatenation. My question is, why is building XML via string concatenation (such as a StringBuilder in C#) bad? I've done this several times in the past, as it's sometimes the quickest way for me to get from point A to point B when to comes to the data structures/objects I'm working with. So far, I have come up with a few reasons why this isn't the greatest approach, but is there something I'm overlooking? Why should this be avoided? Probably the biggest reason I can think of is you need to escape your strings manually, and most programmers will forget this. It will work great for them when they test it, but then "randomly" their apps will fail when someone throws an & symbol in their input somewhere. Ok, I'll buy this, but it's really easy to prevent the problem (SecurityElement.Escape to name one). When I do this, I usually omit the XML declaration (i.e. <?xml version="1.0"?>). Is this harmful? Performance penalties? If you stick with proper string concatenation (i.e. StringBuilder), is this anything to be concerned about? Presumably, a class like XmlWriter will also need to do a bit of string manipulation... There are more elegant ways of generating XML, such as using XmlSerializer to automatically serialize/deserialize your classes. Ok sure, I agree. C# has a ton of useful classes for this, but sometimes I don't want to make a class for something really quick, like writing out a log file or something. Is this just me being lazy? If I am doing something "real" this is my preferred approach for dealing w/ XML.

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  • Contrary to Python 3.1 Docs, hash(obj) != id(obj). So which is correct?

    - by Don O'Donnell
    The following is from the Python v3.1.2 documentation: From The Python Language Reference Section 3.3.1 Basic Customization: object.__hash__(self) ... User-defined classes have __eq__() and __hash__() methods by default; with them, all objects compare unequal (except with themselves) and x.__hash__() returns id(x). From The Glossary: hashable ... Objects which are instances of user-defined classes are hashable by default; they all compare unequal, and their hash value is their id(). This is true up through version 2.6.5: Python 2.6.5 (r265:79096, Mar 19 2010 21:48:26) ... ... >>> class C(object): pass ... >>> c = C() >>> id(c) 11335856 >>> hash(c) 11335856 But in version 3.1.2: Python 3.1.2 (r312:79149, Mar 21 2010, 00:41:52) ... ... >>> class C: pass ... >>> c = C() >>> id(c) 11893680 >>> hash(c) 743355 So which is it? Should I report a documentation bug or a program bug? And if it's a documentation bug, and the default hash() value for a user class instance is no longer the same as the id() value, then it would be interesting to know what it is or how it is calculated, and why it was changed in version 3.

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  • Advanced All In One .NET Framework (should i go for a software factory ?)

    - by alfredo dobrekk
    Hi, i m starting a new project that would basically take input from user and save them to database among about 30 screens, and i would like to find a framework that will allow the maximum number of these features out of the box : .net c#. windows form. unit testing continuous integration logging screens with lists, combo boxes, text boxes, add, delete, save, cancel that are easy to update when you add a property to your classes or a field to your database. auto completion on controls to help user find its way use of an orm like nhibernate easy multithreading and display of wait screens for user easy undo redo tabbed child windows search forms ability to grant access to some functionnalities according to user profiles mvp/mvvm or whatever design patterns either some code generation from database to c# classe or generation of database schema from c# classes some kind of database versioning / upgrade to easily update database when i release patches to application once in production automatic control resizing code metrics analysis some code generator i can use against my entities that would generate some rough form i can rearrange after code documentation generator ... At this point i have 3 options : Build from scratch on top of clr :( Find functionnalities among several open source framework and use them as a stack for infrastucture Find a "software factory" I know its lot but i really would like to use existing code to build upon so i can focus on business rules. What open source tools would u use to achieve these ?

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  • Need help extrapolating Java code

    - by Berlioz
    If anyone familiar with Rebecca Wirfs-Brock, she has a piece of Java code found in her book titled, Object Design: Roles, Responsibilities, and Collaborations. Here is the quote Applying Double Dispatch to a Specific Problem To implement the game Rock, Paper, Scissors we need to write code that determines whether one object “beats” another. The game has nine possible outcomes based on the three kinds of objects. The number of interactions is the cross product of the kinds of objects. Case or switch statements are often governed by the type of data that is being operated on. The object-oriented language equivalent is to base its actions on the class of some other object. In Java, it looks like this Here is the piece of Java code on page 16 ' import java.util.*; import java.lang.*; public class Rock { public static void main(String args[]) { } public static boolean beats(GameObject object) { if (object.getClass.getName().equals("Rock")) { result = false; } else if (object.getClass.getName().equals("Paper")) { result = false; } else if(object.getClass.getName().equals("Scissors")) { result = true; } return result; } }' ===This is not a very good solution. First, the receiver needs to know too much about the argument. Second, there is one of these nested conditional statements in each of the three classes. If new kinds of objects could be added to the game, each of the three classes would have to be modified. Can anyone share with me how to get this "less than optimal" piece of code to work in order to see it 'working'. She proceeds to demonstrate a better way, but I will spare you. Thanks

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  • How to check at runtime if a class implements certain interface?

    - by mare
    Let's say I have some content classes like Page, TabGroup, Tab, etc. Certain of those will be implementing my IWidgetContainer interface - it means they will geet an additional field named ContainedItems from the interface and some methods for manipulating this field. Now I need to reflect the fact that some class implements this interface by rendering out some special custom controls in my ASP.NET MVC Views (like jQuery Add/Remove/Move/Reorder buttons). For instance, TabGroup will implement IWidgetContainer because it will contain tabs but a tab will not implement it because it won't have the ability to contain anything. So I have to somehow check in my view, when I render my content objects (The problem is, I use my base class as strong type in my view not concrete classes), whether it implements IWidgetContainer. How is that possible or have I completely missed something? To rephrase the question, how do you reflect some special properties of a class (like interface implementation) in the UI in general (not necessarily ASP.NET MVC)? Here's my code so far: [DataContract] public class ContentClass { [DataMember] public string Slug; [DataMember] public string Title; [DataMember] protected ContentType Type; } [DataContract] public class Group : ContentClass, IWidgetContainer { public Group() { Type = ContentType.TabGroup; } public ContentList ContainedItems { get; set; } public void AddContent(ContentListItem toAdd) { throw new NotImplementedException(); } public void RemoveContent(ContentListItem toRemove) { throw new NotImplementedException(); } } [DataContract] public class GroupElement : ContentClass { public GroupElement() { Type = ContentType.Tab; } } Interface: interface IWidgetContainer { [DataMember] ContentList ContainedItems { get; set; } void AddContent(ContentListItem toAdd); void RemoveContent(ContentListItem toRemove); }

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  • C++ socket protocol design issue (ring inclusion)

    - by Martin Lauridsen
    So I have these two classes, mpqs_client and client_protocol. The mpqs_client class handles a Boost socket connection to a server (sending and receiving messages with some specific format. Upon receiving a message, it calls a static method, parse_message(..), in the class client_protocol, and this method should analyse the message received and perform some corresponding action. Given some specific input, the parse_message method needs to send some data back to the server. As mentioned, this happens through the class mpqs_client. So I could, from mpqs_client, pass "this" to parse_message(..) in client_protocol. However, this leads to a two-way association relationship between the two classes. Something which I reckon is not desireable. Also, to implement this, I would need to include the other in each one, and this gives me a terrible pain. I am thinking this is more of a design issue. What is the best solution here? Code is posted below. Class mpqs_client: #include "mpqs_client.h" mpqs_client::mpqs_client(boost::asio::io_service& io_service, tcp::resolver::iterator endpoint_iterator) : io_service_(io_service), socket_(io_service) { ... } ... void mpqs_client::write(const network_message& msg) { io_service_.post(boost::bind(&mpqs_client::do_write, this, msg)); } Class client_protocol: #include "../network_message.hpp" #include "../protocol_consts.h" class client_protocol { public: static void parse_message(network_message& msg, mpqs_sieve **instance_, mpqs_client &client_) { ... switch (type) { case MPQS_DATA: ... break; case POLYNOMIAL_DATA: ... break; default: break; } }

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  • Which is the correct design pattern for my PHP application?

    - by user1487141
    I've been struggling to find good way to implement my system which essentially matches the season and episode number of a show from a string, you can see the current working code here: https://github.com/huddy/tvfilename I'm currently rewriting this library and want a nicer way to implement how the the match happens, currently essentially the way it works is: There's a folder with classes in it (called handlers), every handler is a class that implements an interface to ensure a method called match(); exists, this match method uses the regex stored in a property of that handler class (of which there are many) to try and match a season and episode. The class loads all of these handlers by instantiating each one into a array stored in a property, when I want to try and match some strings the method iterates over these objects calling match(); and the first one that returns true is then returned in a result set with the season and episode it matched. I don't really like this way of doing it, it's kind of hacky to me, and I'm hoping a design pattern can help, my ultimate goal is to do this using best practices and I wondered which one I should use? The other problems that exist are: More than one handler could match a string, so they have to be in an order to prevent the more greedy ones matching first, not sure if this is solvable as some of the regex patterns have to be greedy, but possibly a score system, something that shows a percentage of how likely the match is correct, i'd have no idea how to actually implement this though. I'm not if instantiating all those handlers is a good way of doing it, speed is important, but using best practices and sticking to design patterns to create good, extensible and maintainable code is my ultimate priority. It's worth noting the handler classes sometimes do other things than just regex matching, they sometimes prep the string to be matched by removing common words etc. Cheers for any help Billy

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