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  • nhibernate subclass in code

    - by Antonio Nakic Alfirevic
    I would like to set up table-per-classhierarchy inheritance in nhibernate thru code. Everything else is set in XML mapping files except the subclasses. If i up the subclasses in xml all is well, but not from code. This is the code i use - my concrete subclass never gets created:( //the call NHibernate.Cfg.Configuration config = new NHibernate.Cfg.Configuration(); SetSubclass(config, typeof(TAction), typeof(tActionSub1), "Procedure"); //the method public static void SetSubclass(Configuration configuration, Type baseClass, Type subClass, string discriminatorValue) { PersistentClass persBaseClass = configuration.ClassMappings.Where(cm => cm.MappedClass == baseClass).Single(); SingleTableSubclass persSubClass = new SingleTableSubclass(persBaseClass); persSubClass.ClassName = subClass.AssemblyQualifiedName; persSubClass.DiscriminatorValue = discriminatorValue; persSubClass.EntityPersisterClass = typeof(SingleTableEntityPersister); persSubClass.ProxyInterfaceName = (subClass).AssemblyQualifiedName; persSubClass.NodeName = subClass.Name; persSubClass.EntityName = subClass.FullName; persBaseClass.AddSubclass(persSubClass); } the Xml mapping looks like this: <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Riz.Pcm.Domain.BusinessObjects" assembly="Riz.Pcm.Domain"> <class name="Riz.Pcm.Domain.BusinessObjects.TAction, Riz.Pcm.Domain" table="dbo.tAction" lazy="true"> <id name="Id" column="ID"> <generator class="guid" /> </id> <discriminator type="String" formula="(select jt.Name from TJobType jt where jt.Id=JobTypeId)" insert="true" force="false"/> <many-to-one name="Session" column="SessionID" class="TSession" /> <property name="Order" column="Order1" /> <property name="ProcessStart" column="ProcessStart" /> <property name="ProcessEnd" column="ProcessEnd" /> <property name="Status" column="Status" /> <many-to-one name="JobType" column="JobTypeID" class="TJobType" /> <many-to-one name="Unit" column="UnitID" class="TUnit" /> <bag name="TActionProperties" lazy="true" cascade="all-delete-orphan" inverse="true" > <key column="ActionID"></key> <one-to-many class="TActionProperty"></one-to-many> </bag> <!--<subclass name="Riz.Pcm.Domain.tActionSub" discriminator-value="ZPower"></subclass>--> </class> </hibernate-mapping> What am I doing wrong? I can't find any examples on google:(

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  • Implementing INotifyPropertyChanged with PostSharp 1.5

    - by no9
    Hello all. Im new to .NET and WPF so i hope i will ask the question correctly. I am using INotifyPropertyChanged implemented using PostSharp 1.5: [Serializable, DebuggerNonUserCode, AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class, AllowMultiple = false, Inherited = false), MulticastAttributeUsage(MulticastTargets.Class, AllowMultiple = false, Inheritance = MulticastInheritance.None, AllowExternalAssemblies = true)] public sealed class NotifyPropertyChangedAttribute : CompoundAspect { public int AspectPriority { get; set; } public override void ProvideAspects(object element, LaosReflectionAspectCollection collection) { Type targetType = (Type)element; collection.AddAspect(targetType, new PropertyChangedAspect { AspectPriority = AspectPriority }); foreach (var info in targetType.GetProperties(BindingFlags.Public | BindingFlags.Instance).Where(pi => pi.GetSetMethod() != null)) { collection.AddAspect(info.GetSetMethod(), new NotifyPropertyChangedAspect(info.Name) { AspectPriority = AspectPriority }); } } } [Serializable] internal sealed class PropertyChangedAspect : CompositionAspect { public override object CreateImplementationObject(InstanceBoundLaosEventArgs eventArgs) { return new PropertyChangedImpl(eventArgs.Instance); } public override Type GetPublicInterface(Type containerType) { return typeof(INotifyPropertyChanged); } public override CompositionAspectOptions GetOptions() { return CompositionAspectOptions.GenerateImplementationAccessor; } } [Serializable] internal sealed class NotifyPropertyChangedAspect : OnMethodBoundaryAspect { private readonly string _propertyName; public NotifyPropertyChangedAspect(string propertyName) { if (string.IsNullOrEmpty(propertyName)) throw new ArgumentNullException("propertyName"); _propertyName = propertyName; } public override void OnEntry(MethodExecutionEventArgs eventArgs) { var targetType = eventArgs.Instance.GetType(); var setSetMethod = targetType.GetProperty(_propertyName); if (setSetMethod == null) throw new AccessViolationException(); var oldValue = setSetMethod.GetValue(eventArgs.Instance, null); var newValue = eventArgs.GetReadOnlyArgumentArray()[0]; if (oldValue == newValue) eventArgs.FlowBehavior = FlowBehavior.Return; } public override void OnSuccess(MethodExecutionEventArgs eventArgs) { var instance = eventArgs.Instance as IComposed<INotifyPropertyChanged>; var imp = instance.GetImplementation(eventArgs.InstanceCredentials) as PropertyChangedImpl; imp.OnPropertyChanged(_propertyName); } } [Serializable] internal sealed class PropertyChangedImpl : INotifyPropertyChanged { private readonly object _instance; public PropertyChangedImpl(object instance) { if (instance == null) throw new ArgumentNullException("instance"); _instance = instance; } public event PropertyChangedEventHandler PropertyChanged; internal void OnPropertyChanged(string propertyName) { if (string.IsNullOrEmpty(propertyName)) throw new ArgumentNullException("propertyName"); var handler = PropertyChanged as PropertyChangedEventHandler; if (handler != null) handler(_instance, new PropertyChangedEventArgs(propertyName)); } } } Then i have a couple of classes (user and adress) that implement [NotifyPropertyChanged]. It works fine. But what i want would be that if the child object changes (in my example address) that the parent object gets notified (in my case user). Would it be possible to expand this code so it automaticly creates listeners on parent objects that listen for changes in its child objets?

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  • Hidden Features of PHP?

    - by George Mauer
    EDIT: This didn't really start as a hidden features of PHP topic, but thats what it ended up as, so go nuts. I know this sounds like a point-whoring question but let me explain where I'm coming from. Out of college I got a job at a PHP shop. I worked there for a year and a half and thought that I had learned all there was to learn about programming. Then I got a job as a one-man internal development shop at a sizable corporation where all the work was in C#. In my commitment to the position I started reading a ton of blogs and books and quickly realized how wrong I was to think I knew everything. I learned about unit testing, dependency injection and decorator patterns, the design principle of loose coupling, the composition over inheritance debate, and so on and on and on - I am still very much absorbing it all. Needless to say my programming style has changed entirely in the last year. Now I find myself picking up a php project doing some coding for a friend's start-up and I feel completely constrained as opposed to programming in C#. It really bothers me that all variables at a class scope have to be referred to by appending '$this-' . It annoys me that none of the IDEs that I've tried have very good intellisense and that my SimpleTest unit tests methods have to start with the word 'test'. It drives me crazy that dynamic typing keeps me from specifying implicitly which parameter type a method expects, and that you have to write a switch statement to do method overloads. I can't stand that you can't have nested namespaces and have to use the :: operator to call the base class's constructor. Now I have no intention of starting a PHP vs C# debate, rather what I mean to say is that I'm sure there are some PHP features that I either don't know about or know about yet fail to use properly. I am set in my C# universe and having trouble seeing outside the glass bowl. So I'm asking, what are your favorite features of PHP? What are things you can do in it that you can't or are more difficult in the .Net languages?

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  • Is this way of storing typed objects in memory good?

    - by Pindatjuh
    This is an "is this okay, or can it be done better" question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 platform for my language. My goal includes typed objects. Idea: Every primitive is a semi-class (it can be used as if it was a normal class, but it's stored more compact). Every class is represented by primitives and some meta-data (containing class-properties, inheritance stuff, etc.). The meta-data is complex: it doesn't use fields but instead context-switches. For primitives, the meta-data is very small, compared to a "real" class, which is alot bigger. This enables another idea that "primitives are objects", in my language, which I found nessecairy. Example: If I have an array of 32 booleans, then the pure content of this array is exactly 4 byte (32 bits of booleans). The meta-data will contain flags that the type is an array of booleans, which contains 32 entries. The meta-data is very compacted, on bit-level: using a sort of "packing" mechanism, which is read by a FSM at runtime, when doing inspection of the type (like when passing the object to methods for checking, etc.) For instance (read from left to right, top to bottom, remember vertical possition when going to the right, and check nearest column header for meaning of switch): Primitive? Array? Type-Meta 1 Byte? || Size (1 byte) 1 1 [...] 1 [...] done 0 2 Bytes? || Size (2 bytes) 1 [...] done || Size (4 bytes) 0 [...] done Integer? 1 Byte? 2 Bytes? 0 1 0 1 done 1 done 0 done Boolean? Byte? 0 1 0 done 1 done More-Primitives 0 .... Class-Stuff (Huge) 0 ... (After reaching done the data is inserted. || = byte alignement. [...] is variable sized. ... is not described here, for simplicity. And let's call them cost-based-data-structures.) For an array of 32 booleans containing all true values, the memory for this type would be (read top-down): 1 Primitive 1 Array 1 ArrayType: Primitive 0 Not-Array 0 Not-Integer 1 Boolean 0 Not-Byte (thus bit) 1 Integer Size: 1 Byte 00100000 Array size 11111111 11111111 11111111 11111111 Data Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 11111111 11111111 11111111 11111111 Is this okay, or can it be done better?

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  • Setting up nginx as proxy to apache; All good, but nginx doesn't serve media

    - by becomingGuru
    I have set it up such that nginx proxies request and sends django requests to apache and serves media itself. Following documents my setup: Nginx Configuration: /etc/nginx/nginx.conf user www-data; worker_processes 1; error_log /var/log/nginx/error.log; pid /var/run/nginx.pid; events { worker_connections 1024; } http { include /etc/nginx/mime.types; default_type application/octet-stream; access_log /var/log/nginx/access.log; sendfile on; tcp_nopush on; #keepalive_timeout 0; keepalive_timeout 65; tcp_nodelay on; gzip on; include /etc/nginx/sites-enabled/*; } ===== ngnix proxy /etc/nginx/proxy.conf ============ proxy_redirect off; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; client_max_body_size 10m; client_body_buffer_size 128k; proxy_connect_timeout 90; proxy_send_timeout 90; proxy_read_timeout 90; proxy_buffer_size 4k; proxy_buffers 4 32k; proxy_busy_buffers_size 64k; proxy_temp_file_write_size 64k; =========== Nginx server file: /etc/nginx/sites-enabled/some-name.txt ========== server { listen 208.109.252.110:80; server_name netconf; autoindex on; access_log /home/site/server_logs/nginx_access.log; error_log /home/site/server_logs/nginx_error.log; location / { proxy_pass http://127.0.0.1:80/; include /etc/nginx/proxy.conf; } location /site_media/ { root /home/site/folder/static; } } ========== Nginx very well proxies the request and passes to apache, the required requests, but doesn't serve the media. In the last server file, location site_media is not served, at all. :( Everything seems perfect to me. What is wrong? Thanks in advance.

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  • Adding a valuetype to IDL, compile and it fails with "No factory found"

    - by jim
    I can't figure out why the client keeps complaining about the not finding the factory method. I've tried the IDL with and without the "factory" keyword and that didn't change the behavior. The SDMGeoVT IDL matches other objects used (which run successfully). The SDMGeoVT classes generated match other generated classes in regards to inheritance and methods. The IDL is as follows; The idlj compiler runs w/o error. I implement the function on the server and I see the server code run and serialize the object over the wire (the server code runs fine). The client bombs with the following stack trace (the first couple of lines is from the jacORB library). I've created a small app just to compile and test the code (ArrayClient & ArrayServer). The base app (from the jacORB demo) works fine. I've tried using the base class OFBaseVT and a single object (SDMGeoVT vs the list return) and have the same issue. 2010-05-27 15:37:11.813 FINE read GIOP message of size 100 from ClientGIOPConnection to 127.0.0.1:47030 (1e4853f) 2010-05-27 15:37:11.813 FINE read GIOP message of size 100 from ClientGIOPConnection to 127.0.0.1:47030 (1e4853f) org.omg.CORBA.MARSHAL: No factory found for: IDL:pl/SDMGeoVT:1.0 at org.jacorb.orb.CDRInputStream.read_untyped_value(CDRInputStream.java:2906) at org.jacorb.orb.CDRInputStream.read_typed_value(CDRInputStream.java:3082) at org.jacorb.orb.CDRInputStream.read_value(CDRInputStream.java:2679) at com.helloworld.pl.SDMGeoVTHelper.read(SDMGeoVTHelper.java:106) at com.helloworld.pl.SDMGeoVTListHelper.read(SDMGeoVTListHelper.java:51) at com.helloworld.pl._PLManagerIFStub.getSDMGeos(_PLManagerIFStub.java:28) at com.helloworld.ArrayClient.<init>(ArrayClient.java:40) at com.helloworld.ArrayClient.main(ArrayClient.java:125) valuetype SDMGeoVT : common::OFBaseVT{ private string sdmName; private string zip; private string atz; private long long primaryDeptId; private string deptName; factory instance(in string name,in string ZIP,in string ATZ,in long long primaryDeptId,in string deptName,in string name); string getZIP(); void setZIP(in string ZIP); string getATZ(); void setATZ(in string ATZ); long long getPrimaryDeptId(); void setPrimaryDeptId(in long long primaryDeptId); string getDeptName(); void setDeptName(in string deptName); }; typedef sequence<SDMGeoVT> SDMGeoVTList; interface PLManagerIF : PublicManagerIF { pl::SDMGeoVTList getSDMGeos(in framework::ITransactionHandle tHandle, in long long productionLocationId); };

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  • Apache server completely freezes until it gets restarted

    - by nbv4
    My server does this every few days. What sucks is that it always seems to do this right after I go to bed, so when I wake up, I'm greeted with the fact that my server has been down for the past 6 or 7 hours. When I first noticed this, I added a cronjob that tries to restart the server every 15 minutes, but I guess that didn't fix it. Once I noticed the server was down, I can this command: /etc/init.d/apache2 restart * Restarting web server apache2 apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName ... waiting ...........................................................apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName httpd (pid 17597) already running ...which is odd, because a restart should restart the server, even if it's already running, correct? I eventually had to "stop" then "start" to get it working again. I then looked through the logs, and found something very weird. It seems that around the time the server crashed, the logs have entries that are wildly out of order. It looks a little like this: xx.xxx.xxx.x - - [21/Apr/2010:06:32:05 -0400] "GET / blah" xx.xxx.xxx.x - - [21/Apr/2010:06:51:25 -0400] "GET / blah" x.xx.xxx.xxx - - [21/Apr/2010:06:38:23 -0400] "GET / blah" xxx.xx.xx.xx - - [21/Apr/2010:06:31:56 -0400] "GET / blah" xxx.xx.xx.xx - - [21/Apr/2010:06:51:49 -0400] "GET / blah" xx.xx.xxx.xx - - [21/Apr/2010:06:33:20 -0400] "GET / blah" I don't think the problem is memory, because this: tells me that right before the crash, memory usage is fine. I'm running apache with the worker mpm, here are the settings for that: <IfModule mpm_worker_module> StartServers 1 MaxClients 100 MinSpareThreads 5 MaxSpareThreads 10 ThreadsPerChild 10 MaxRequestsPerChild 3000 </IfModule> This apache server is running a bunch of stuff, but most of the traffic comes from a django project I'm hosting, that uses mod_wsgi. There also is a simple machines forum that is running off of mod_fcgid. Those setting are below: <IfModule mod_fcgid.c> MaxRequestsPerProcess 500 MaxProcessCount 3 AddHandler fcgid-script .php .fcgi AddHandler cgi-script .cgi .pl FCGIWrapper "/usr/bin/php-cgi" .php </IfModule> Anyone know of anything else I can check? I've just about tweaked every single setting I can think of, yet these freezes still happen.

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  • feeling insufficient while looking for a programming job ...

    - by user325661
    Hello everybody It's really dream to be programmer for me.So i always wanted to be .I had so small knowledges from commodore basic which i couldn't figure out anything in it .Then i tried to learn Visual basic 6 by myself and result wasn't good as i expected because i even didn't understand classes.Then i left to learning programming and to dream to be programmer. But challenge hadn't finished yet . After all of these i started to learn c# and i did chess engine which i hadn't believe that i can create one.I sometimes feel that i understand many thing about programming like knowing classes ,inheritance,abstract class and methods why exist , interfaces ,extension methods ,static classes ,threads. but i am not expert all in it . i just know that as i need . i don't know still i will learn many thing about these.i have also learned html, css2 , php and database concepts a little sql ,tables relations between primary keys etc but i haven't used them in praticaly . i just did some samples so i feel i am lack of knowledges. As a result still i can't evaluate my skills and can't decide what is my level.I just feel myself one step ahead of junior sometimes :) . Still can't decide that it is time to job seeking. While searching job on web i have never seen a junior advertisement. All looking for a good experiencing one.Nobody care about juniors. When found job advertisement which i feel sufficient myself a little then i start to feel that i think i can't do what they want from me and loosing job after have it in short time would leave many crap feelings into my low self-confidence. Please advise me something ... Also i want to ask some of concentrate questions. 1) If i enter a job which i can't provide their expectations should be in employers responsibility to test me while apply the job ? 2) If i answer "yes , i can " questions which is abstract(for example: can u do something like this) would be my responsibility ? Because such abstract questions is not clear and can't know before start it what i really can or not . 3) i have no professional experiences in this job so i even don't know how teams working on projects but a friend of me said that programmers only write method bodies while seniors create all project.So it looks what i can do really easy but i feel that small companies doesn't work like this so it is better work in a big company for starting who has seniors? 4)last applied job was looking for c# . net developer but then i learn that they need .net web developer.Does it take long time to learn specific sides of web programming while knowing c# desktop programming ? Thanks for all answers since now.

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  • Criteria query returns hydrated object in SQLite but not SqlServer

    - by Berryl
    I have a method that returns a resource fully hydrated when the db is SQLite but when the identical code is used by SqlServer the object is not fully hydrated. I'll explain that with the code after some brief background. I my domain various otherwise unrelated things like an Employee or a Machine can be used as a Resource that can be allocated to. In the object model an example of this would be: /// <summary>Wraps a <see cref="StaffMember"/> in a <see cref="ResourceBase"/>. </summary> public class StaffMemberResource : ResourceBase { public virtual StaffMember StaffMember { get; private set; } public StaffMemberResource(StaffMember staffMember) { Check.RequireNotNull<StaffMember>(staffMember); base.BusinessId = staffMember.Number.ToString(); base.Name = staffMember.Name.ToString(); base.OrganizationName = staffMember.Department.Name; StaffMember = staffMember; } [UsedImplicitly] protected StaffMemberResource() { } } And in the db tables, there is a table per class inheritance where the ResourceBase has a discriminator and the id of the actual resource (ie, StaffMember) StaffMember - 1 ---- M- ResourceBase - 1 ----- M - Allocation The Code public override StaffMemberResource BuildResource(IActivityService activityService) { var sessionFactory = _GetSessionFactory(); var session = sessionFactory.GetCurrentSession(); StaffMemberResource result; using (var tx = session.BeginTransaction()) { var propertyName = ExprHelper.GetPropertyName<StaffMember>(x => x.Number); var staff = session.CreateCriteria<StaffMember>() .Add(Restrictions.Eq(propertyName, new EmployeeNumber(_testData.Resource_1.BusinessId))) .UniqueResult<StaffMember>(); if (staff == null) { ... build up a staff member result = new StaffMemberResource(staff); } else { ////////// var property = ExprHelper.GetPropertyName<StaffMemberResource>(x => x.StaffMember); result = session.CreateCriteria<StaffMemberResource>() .Add(Restrictions.Eq(property, staff)) .UniqueResult<StaffMemberResource>(); } /////////// tx.Commit(); } return result; } It's that second criteria query that works "properly" with SQLite but not with SqlServer. By properly I mean that the employee numer is translated into a ResourceBase.BusinessId, Name is flattened out into a ResourceBase.Name, etc. Does anyone know why this might be? Cheers, Berryl

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  • How to properly downcast in C# with a SWIG generated interface?

    - by JG
    I've got a very large and mature C++ code base that I'm trying to use SWIG on to generate a C# interface for. I cannot change the actual C++ code itself but we can use whatever SWIG offers in the way of extending/updating it. I'm facing an issue where a function C++ is written as such: A* SomeClass::next(A*) The caller might do something like: A* acurr = 0; while( (acurr = sc->next(acurr)) != 0 ){ if( acurr isoftype B ){ B* b = (B*)a; ...do some stuff with b.. } elseif( acurr isoftype C ) ... } Essentially, iterating through a container elements that depending on their true type, do something different. The SWIG generated C# layer for the "next" function unfortunately does the following: return new A(); So the calling code in C# land cannot determine if the returned object is actually a derived class or not, it actually appears to always be the base class (which does make sense). I've come across several solutions: Use the %extend SWIG keyword to add a method on an object and ultimately call dynamic_cast. The downside to this approach, as I see it, is that this requires you to know the inheritance hierarchy. In my case it is rather huge and I see this is as a maintenance issue. Use the %factory keyword to supply the method and the derived types and have SWIG automatically generate the dynamic_cast code. This appears to be a better solution that the first, however upon a deeper look it still requires you to hunt down all the methods and all the possible derived types it could return. Again, a huge maintenance issue. I wish I had a doc link for this but I can't find one. I found out about this functionality by looking through the example code that comes with SWIG. Create a C# method to create an instance of the derived object and transfer the cPtr to the new instance. While I consider this clumsy, it does work. See an example below. public static object castTo(object fromObj, Type toType) { object retval = null; BaseClass fromObj2 = fromObj as BaseClass; HandleRef hr = BaseClass.getCPtr(fromObj2); IntPtr cPtr = hr.Handle; object toObj = Activator.CreateInstance(toType, cPtr, false); // make sure it actually is what we think it is if (fromObj.GetType().IsInstanceOfType(toObj)) { return toObj; } return retval; } Are these really the options? And if I'm not willing to dig through all the existing functions and class derivations, then I'm left with #3? Any help would be appreciated.

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  • Overwhelmed by design patterns... where to begin?

    - by Pete
    I am writing a simple prototype code to demonstrate & profile I/O schemes (HDF4, HDF5, HDF5 using parallel IO, NetCDF, etc.) for a physics code. Since focus is on IO, the rest of the program is very simple: class Grid { public: floatArray x,y,z; }; class MyModel { public: MyModel(const int &nip1, const int &njp1, const int &nkp1, const int &numProcs); Grid grid; map<string, floatArray> plasmaVariables; }; Where floatArray is a simple class that lets me define arbitrary dimensioned arrays and do mathematical operations on them (i.e. x+y is point-wise addition). Of course, I could use better encapsulation (write accessors/setters, etc.), but that's not the concept I'm struggling with. For the I/O routines, I am envisioning applying simple inheritance: Abstract I/O class defines read & write functions to fill in the "myModel" object HDF4 derived class HDF5 HDF5 using parallel IO NetCDF etc... The code should read data in any of these formats, then write out to any of these formats. In the past, I would add an AbstractIO member to myModel and create/destroy this object depending on which I/O scheme I want. In this way, I could do something like: myModelObj.ioObj->read('input.hdf') myModelObj.ioObj->write('output.hdf') I have a bit of OOP experience but very little on the Design Patterns front, so I recently acquired the Gang of Four book "Design Patterns: Elements of Reusable Object-Oriented Software". OOP designers: Which pattern(s) would you recommend I use to integrate I/O with the myModel object? I am interested in answering this for two reasons: To learn more about design patterns in general Apply what I learn to help refactor an large old crufty/legacy physics code to be more human-readable & extensible. I am leaning towards applying the Decerator pattern to myModel, so I can attach the I/O responsibilities dynamically to myModel (i.e. whether to use HDF4, HDF5, etc.). However, I don't feel very confident that this is the best pattern to apply. Reading the Gang of Four book cover-to-cover before I start coding feels like a good way to develop an unhealthy caffeine addiction. What patterns do you recommend?

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  • How to learn proper C++?

    - by Chris
    While reading a long series of really, really interesting threads, I've come to a realization: I don't think I really know C++. I know C, I know classes, I know inheritance, I know templates (& the STL) and I know exceptions. Not C++. To clarify, I've been writing "C++" for more than 5 years now. I know C, and I know that C and C++ share a common subset. What I've begun to realize, though, is that more times than not, I wind up treating C++ something vaguely like "C with classes," although I do practice RAII. I've never used Boost, and have only read up on TR1 and C++0x - I haven't used any of these features in practice. I don't use namespaces. I see a list of #defines, and I think - "Gracious, that's horrible! Very un-C++-like," only to go and mindlessly write class wrappers for the sake of it, and I wind up with large numbers (maybe a few per class) of static methods, and for some reason, that just doesn't seem right lately. The professional in me yells "just get the job done," the academic yells "you should write proper C++ when writing C++" and I feel like the point of balance is somewhere in between. I'd like to note that I don't want to program "pure" C++ just for the sake of it. I know several languages. I have a good feel for what "Pythonic" is. I know what clean and clear PHP is. Good C code I can read and write better than English. The issue is that I learned C by example, and picked up C++ as a "series of modifications" to C. And a lot of my early C++ work was creating class wrappers for C libraries. I feel like my own personal C-heavy background while learning C++ has sort of... clouded my acceptance of C++ in it's own right, as it's own language. Do the weathered C++ lags here have any advice for me? Good examples of clean, sharp C++ to learn from? What habits of C does my inner-C++ really need to break from? My goal here is not to go forth and trumpet "good" C++ paradigm from rooftops for the sake of it. C and C++ are two different languages, and I want to start treating them that way. How? Where to start? Thanks in advance! Cheers, -Chris

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  • Can this way of storing typed objects be improved?

    - by Pindatjuh
    This is an "can it be improved"-question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 Windows platform for my language. My goal includes typed objects. Idea: Every primitive is a semi-class (it can be used as if it was a normal class, but it's stored more compact). Every class is represented by primitives and some meta-data (containing class-properties, inheritance stuff, etc.). The meta-data is complex: it doesn't use fields but instead context-switches. For primitives, the meta-data is very small, compared to a "real" class, which is alot bigger. This enables another idea that "primitives are objects", in my language, which I found nessecairy. Example: If I have an array of 32 booleans, then the pure content of this array is exactly 4 byte (32 bits of booleans). The meta-data will contain flags that the type is an array of booleans, which contains 32 entries. The meta-data is very compacted, on bit-level: using a sort of "packing" mechanism, which is read by a FSM at runtime, when doing inspection of the type (like when passing the object to methods for checking, etc.) For instance (read from left to right, top to bottom, remember vertical position when going to the right, and check nearest column header for meaning of switch): Primitive? Array? Type-Meta 1 Byte? || Size (1 byte) 1 1 [...] 1 [...] done 0 2 Bytes? || Size (2 bytes) 1 [...] done || Size (4 bytes) 0 [...] done Integer? 1 Byte? 2 Bytes? 0 1 0 1 done 1 done 0 done Boolean? Byte? 0 1 0 done 1 done More-Primitives 0 .... Class-Stuff (Huge) 0 ... (After reaching done the data is inserted. || = byte alignment. [...] is variable sized. ... is not described here, for simplicity. And let's call them cost-based-data-structures.) For an array of 32 booleans containing all true values, the memory for this type would be (read top-down): 1 Primitive 1 Array 1 ArrayType: Primitive 0 Not-Array 0 Not-Integer 1 Boolean 0 Not-Byte (thus bit) 1 Integer Size: 1 Byte 00100000 Array size 01010101 01010101 01010101 01010101 Data (user defined) Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 01010101 01010101 01010101 01010101 How can I improve this? (Both performance- and memory-consumption wise)

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  • Varnish server in front of nginx server with multiple virtualhosts

    - by Garreth 00
    I have tried to search for a solution for this, but can't find any documentation/tips on my specific setup. My setup: Backendserver: ngnix: 2 different websites (2 top domains) in virtualenv, running gunicorn/python/django Backendserver hardware(VPS) 2gb ram, 8 CPU Databaseserver: postgresql - pg_bouncer Backendserver hardware (VPS) 1gb ram, 8 CPU Varnishserver: only running varnish Varnishserver hardware (VPS) 1gb ram, 8 CPU I'm trying to set up a varnish server to handle rare spike in traffic (20 000 unique req/s) The spike happens when a tv program mention one of the sites. What do I need to do, to make the varnish server cache both sites/domains on my backendserver? My /etc/varnish/default.vcl : backend django_backend { .host = "local.backendserver.com"; .port = "8080"; } My /usr/local/nginx/site-avaible/domain1.com upstream gunicorn_domain1 { server unix:/home/<USER>/.virtualenvs/<DOMAIN1>/<APP1>/run/gunicorn.sock fail_timeout=0; } server { listen 80; listen 8080; server_name domain1.com; rewrite ^ http://www.domains.com$request_uri? permanent; } server { listen 80 default_server; listen 8080; client_max_body_size 4G; server_name www.domain1.com; keepalive_timeout 5; # path for static files root /home/<USER>/<APP>-media/; location / { proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off; if (!-f $request_filename) { proxy_pass http://gunicorn_domain1; break; } } } My /usr/local/nginx/site-avaible/domain2.com upstream gunicorn_domain2 { server unix:/home/<USER>/.virtualenvs/<DOMAIN2>/<APP2>/run/gunicorn.sock fail_timeout=0; } server { listen 80; listen 8080; server_name domain2.com; rewrite ^ http://www.domains.com$request_uri? permanent; } server { listen 80; listen 8080; client_max_body_size 4G; server_name www.domain2.com; keepalive_timeout 5; # path for static files root /home/<USER>/<APP>-media/; location / { proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off; if (!-f $request_filename) { proxy_pass http://gunicorn_domain2; break; } } } Right now, If I try the Ip of the varnishserver I only get served domain1.com. Would everything be correct if I change the DNS of the two domain to point to the varnishserver, or is there extra setup before it would work? Question 2: Do I need a dedicated server for varnish, or could I just install varnish on my backendserver, or would the server run out of memory quick?

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  • Class template specializations with shared functionality

    - by Thomas
    I'm writing a simple maths library with a template vector type: template<typename T, size_t N> class Vector { public: Vector<T, N> &operator+=(Vector<T, N> const &other); // ... more operators, functions ... }; Now I want some additional functionality specifically for some of these. Let's say I want functions x() and y() on Vector<T, 2> to access particular coordinates. I could create a partial specialization for this: template<typename T> class Vector<T, 3> { public: Vector<T, 3> &operator+=(Vector<T, 3> const &other); // ... and again all the operators and functions ... T x() const; T y() const; }; But now I'm repeating everything that already existed in the generic template. I could also use inheritance. Renaming the generic template to VectorBase, I could do this: template<typename T, size_t N> class Vector : public VectorBase<T, N> { }; template<typename T> class Vector<T, 3> : public VectorBase<T, 3> { public: T x() const; T y() const; }; However, now the problem is that all operators are defined on VectorBase, so they return VectorBase instances. These cannot be assigned to Vector variables: Vector<float, 3> v; Vector<float, 3> w; w = 5 * v; // error: no conversion from VectorBase<float, 3> to Vector<float, 3> I could give Vector an implicit conversion constructor to make this possible: template<typename T, size_t N> class Vector : public VectorBase<T, N> { public: Vector(VectorBase<T, N> const &other); }; However, now I'm converting from Vector to VectorBase and back again. Even though the types are the same in memory, and the compiler might optimize all this away, it feels clunky and I don't really like to have potential run-time overhead for what is essentially a compile-time problem. Is there any other way to solve this?

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  • g++ linker error--typeinfo, but not vtable

    - by James
    I know the standard answer for a linker error about missing typeinfo usually also involves vtable and some virtual function that I forgot to actually define. I'm fairly certain that's not the situation this time. Here's the error: UI.o: In function boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::Resource::GroupByState>(boost::shared_ptr<Graphics::Resource::GroupByState> const&, boost::detail::dynamic_cast_tag)': UI.cpp:(.text._ZN5boost10shared_ptrIN8Graphics7Widgets9WidgetSetEEC1INS1_8Resource12GroupByStateEEERKNS0_IT_EENS_6detail16dynamic_cast_tagE[boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::Resource::GroupByState>(boost::shared_ptr<Graphics::Resource::GroupByState> const&, boost::detail::dynamic_cast_tag)]+0x30): undefined reference totypeinfo for Graphics::Widgets::WidgetSet' Running c++filt on the obnoxious mangled name shows that it actually is looking at .boost::shared_ptr::shared_ptr(boost::shared_ptr const&, boost::detail::dynamic_cast_tag) The inheritance hierarchy looks something like class AbstractGroup { typedef boost::shared_ptr<AbstractGroup> Ptr; ... }; class WidgetSet : public AbstractGroup { typedef boost::shared_ptr<WidgetSet> Ptr; ... }; class GroupByState : public AbstractGroup { ... }; Then there's this: class UI : public GroupByState { ... void LoadWidgets( GroupByState::Ptr resource ); }; Then the original implementation: void UI::LoadWidgets( GroupByState::Ptr resource ) { WidgetSet::Ptr tmp( boost::dynamic_pointer_cast< WidgetSet >(resource) ); if( tmp ) { ... } } Stupid error on my part (trying to cast to a sibling class with a shared parent), even if the error is kind of cryptic. Changing to this: void UI::LoadWidgets( AbstractGroup::Ptr resource ) { WidgetSet::Ptr tmp( boost::dynamic_pointer_cast< WidgetSet >(resource) ); if( tmp ) { ... } } (which I'm fairly sure is what I actually meant to be doing) left me with a very similar error: UI.o: In function boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::_Drawer::Group>(boost::shared_ptr<Graphics::_Drawer::Group> const&, boost::detail::dynamic_cast_tag)': UI.cpp:(.text._ZN5boost10shared_ptrIN8Graphics7Widgets9WidgetSetEEC1INS1_7_Drawer5GroupEEERKNS0_IT_EENS_6detail16dynamic_cast_tagE[boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::_Drawer::Group>(boost::shared_ptr<Graphics::_Drawer::Group> const&, boost::detail::dynamic_cast_tag)]+0x30): undefined reference totypeinfo for Graphics::Widgets::WidgetSet' collect2: ld returned 1 exit status dynamic_cast_tag is just an empty struct in boost/shared_ptr.hpp. It's just a guess that boost might have anything at all to do with the error. Passing in a WidgetSet::Ptr totally eliminates the need for a cast, and it builds fine (which is why I think there's more going on than the standard answer for this question). Obviously, I'm trimming away a lot of details that might be important. My next step is to cut it down to the smallest example that fails to build, but I figured I'd try the lazy way out and take a stab on here first. TIA!

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  • Separation of domain and ui layer in a composite

    - by hansmaad
    Hi all, i'm wondering if there is a pattern how to separate the domain logic of a class from the ui responsibilities of the objects in the domain layer. Example: // Domain classes interface MachinePart { CalculateX(in, out) // Where do we put these: // Draw(Screen) ?? // ShowProperties(View) ?? // ... } class Assembly : MachinePart { CalculateX(in, out) subParts } class Pipe : MachinePart { CalculateX(in, out) length, diamater... } There is an application that calculates the value X for machines assembled from many machine parts. The assembly is loaded from a file representation and is designed as a composite. Each concrete part class stores some data to implement the CalculateX(in,out) method to simulate behaviour of the whole assembly. The application runs well but without GUI. To increase the usability a GUi should be developed on top of the existing implementation (changes to the existing code are allowed). The GUI should show a schematic graphical representation of the assembly and provide part specific dialogs to edit several parameters. To achieve these goals the application needs new functionality for each machine part to draw a schematic representation on the screen, show a property dialog and other things not related to the domain of machine simulation. I can think of some different solutions to implement a Draw(Screen) functionality for each part but i am not happy with each of them. First i could add a Draw(Screen) method to the MachinePart interface but this would mix-up domain code with ui code and i had to add a lot of functionality to each machine part class what makes my domain model hard to read and hard to understand. Another "simple" solution is to make all parts visitable and implement ui code in visitors but Visitor does not belong to my favorite patterns. I could derive UI variants from each machine part class to add the UI implementation there but i had to check if each part class is suited for inheritance and had to be careful on changes to the base classes. My currently favorite design is to create a parallel composite hierarchy where each component stores data to define a machine part, has implementation for UI methods and a factory method which creates instances of the corresponding domain classes, so that i can "convert" a UI assembly to a domain assembly. But there are problems to go back from the created domain hierarchy to the UI hierarchy for showing calculation results in the drawing for example (imagine some parts store some values during the calculation i want to show in the schematic representation after the simluation). Maybe there are some proven patterns for such problems?

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  • Tips for maximizing Nginx requests/sec?

    - by linkedlinked
    I'm building an analytics package, and project requirements state that I need to support 1 billion hits per day. Yep, "billion". In other words, no less than 12,000 hits per second sustained, and preferably some room to burst. I know I'll need multiple servers for this, but I'm trying to get maximum performance out of each node before "throwing more hardware at it". Right now, I have the hits-tracking portion completed, and well optimized. I pretty much just save the requests straight into Redis (for later processing with Hadoop). The application is Python/Django with a gunicorn for the gateway. My 2GB Ubuntu 10.04 Rackspace server (not a production machine) can serve about 1200 static files per second (benchmarked using Apache AB against a single static asset). To compare, if I swap out the static file link with my tracking link, I still get about 600 requests per second -- I think this means my tracker is well optimized, because it's only a factor of 2 slower than serving static assets. However, when I benchmark with millions of hits, I notice a few things -- No disk usage -- this is expected, because I've turned off all Nginx logs, and my custom code doesn't do anything but save the request details into Redis. Non-constant memory usage -- Presumably due to Redis' memory managing, my memory usage will gradually climb up and then drop back down, but it's never once been my bottleneck. System load hovers around 2-4, the system is still responsive during even my heaviest benchmarks, and I can still manually view http://mysite.com/tracking/pixel with little visible delay while my (other) server performs 600 requests per second. If I run a short test, say 50,000 hits (takes about 2m), I get a steady, reliable 600 requests per second. If I run a longer test (tried up to 3.5m so far), my r/s degrades to about 250. My questions -- a. Does it look like I'm maxing out this server yet? Is 1,200/s static files nginx performance comparable to what others have experienced? b. Are there common nginx tunings for such high-volume applications? I have worker threads set to 64, and gunicorn worker threads set to 8, but tweaking these values doesn't seem to help or harm me much. c. Are there any linux-level settings that could be limiting my incoming connections? d. What could cause my performance to degrade to 250r/s on long-running tests? Again, the memory is not maxing out during these tests, and HDD use is nil. Thanks in advance, all :)

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  • Patterns for dynamic CMS components (event driven?)

    - by CitrusTree
    Sorry my title is not great, this is my first real punt at moving 100% to OO as I've been procedural for more years than I can remember. I'm finding it hard to understand if what I'm trying to do is possible. Depending on people's thoughts on the 2 following points, I'll go down that route. The CMS I'm putting together is quote small, however focuses very much on different types of content. I could easily use Drupal which I'm very comfortable with, but I want to give myself a really good reasons to move myself into design patterns / OO-PHP 1) I have created a base 'content' class which I wish to be able to extend to handle different types of content. The base class, for example, handles HTML content, and extensions might handle XML or PDF output instead. On the other hand, at some point I may wish to extend the base class for a given project completely. I.e. if class 'content-v2' extended class 'content' for that site, any calls to that class should actually call 'content-v2' instead. Is that possible? If the code instantiates an object of type 'content' - I actually want it to instantiate one of type 'content-v2'... I can see how to do it using inheritance, but that appears to involve referring to the class explicitly, I can't see how to link the class I want it to use instead dynamically. 2) Secondly, the way I'm building this at the moment is horrible, I'm not happy with it. It feels very linear indeed - i.e. get session details get content build navigation theme page publish. To do this all the objects are called 1-by-1 which is all very static. I'd like it to be more dynamic so that I can add to it at a later date (very closely related to first question). Is there a way that instead of my orchestrator class calling all the other classes 1-by-1, then building the whole thing up at the end, that instead each of the other classes can 'listen' for specific events, then at the applicable point jump in and do their but? That way the orchestrator class would not need to know what other classes were required, and call them 1-by-1. Sorry if I've got this all twisted in my head. I'm trying to build this so it's really flexible.

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  • Serving protected files using Nginx's X-Accel-Redirect header

    - by andybak
    I'm trying to serve protected files using this directive in my nginx.conf: location /secure/ { internal; alias /home/ldr/webapps/nginx/app/secure/; } I'm passing in paths in the form: "/myfile.doc" and the file's path would be: /home/ldr/webapps/nginx/app/secure/myfile.doc I just get 404's when I access "http: //myserver/secure/myfile.doc" (space inserted after http to stop ServerFault converting it to a link) I've tried taking the trailing / off the location directive and that makes no difference. Two questions: How do I fix it! How can I debug problems like this myself? How can I get Nginx to report which path it's looking for? error.log shows nothing and access.log just tells me which url is being requested - this is the bit I already know! It's no fun trying things randomly without any feedback. Here's my entire nginx.conf: daemon off; worker_processes 2; events { worker_connections 1024; } http { include mime.types; default_type application/octet-stream; server { listen 21534; server_name my.server.com; client_max_body_size 5m; location /media/ { alias /home/ldr/webapps/nginx/app/media/; } location / { proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; fastcgi_pass unix:/home/ldr/webapps/nginx/app/myproject/django.sock; fastcgi_pass_header Authorization; fastcgi_hide_header X-Accel-Redirect; fastcgi_hide_header X-Sendfile; fastcgi_intercept_errors off; include fastcgi_params; } location /secure { internal; alias /home/ldr/webapps/nginx/app/secure/; } } } EDIT: I'm trying some of the suggestions here So I've tried: location /secure/ { internal; alias /home/ldr/webapps/nginx/app/; } both with and without the trailing slash on location. I've also tried moving this block before the "location /" directive. The page I linked to has ^~ after 'location' giving: location ^~ /secure/ { ...etc... Not sure what that signifies but it didn't work either!

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  • Is it any loose coupling mechanism in Objective-C + Cocoa like C# delegates or C++Qt signals+slots?

    - by Eye of Hell
    Hello. For a large programs, the standard way to chalenge a complexity is to divide a program code into small objects. Most of the actual programming languages offer this functionality via classes, so is Objective-C. But after source code is separated into small object, the second challenge is to somehow connect them with each over. Standard approaches, supported by most languages are compositon (one object is a member field of another), inheritance, templates (generics) and callbacks. More cryptic techniques include method-level delagates (C#) and signals+slots (C++Qt). I like the delegates / signals idea, since while connecting two objects i can connect individual methods with each over, without objects knowing anything of each over. For C#, it will look like this: var object1 = new CObject1(); var object2 = new CObject2(); object1.SomethingHappened += object2.HandleSomething; In this code, is object1 calls it's SomethingHappened delegate (like a normal method call) the HandleSomething method of object2 will be called. For C++Qt, it will look like this: var object1 = new CObject1(); var object2 = new CObject2(); connect( object1, SIGNAL(SomethingHappened()), object2, SLOT(HandleSomething()) ); The result will be exactly the same. This technique has some advantages and disadvantages, but generally i like it more than interfaces since if program code base grows i can change connections and add new ones without creating tons of interfaces. After examination of Objective-C i havn't found any way to use this technique i like :(. It seems that Objective-C supports message passing perfectly well, but it requres for object1 to have a pointer to object2 in order to pass it a message. If some object needs to be connected to lots of other objects, in Objective-C i will be forced to give him pointers to each of the objects it must be connected. So, the question :). Is it any approach in Objective-C programming that will closely resemble delegate / signal+slot types of connection, not a 'give first object an entire pointer to second object so it can pass a message to it'. Method-level connections are a bit more preferable to me than object-level connection ^_^.

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  • Is typeid of type name always evaluated at compile time in c++ ?

    - by cyril42e
    I wanted to check that typeid is evaluated at compile time when used with a type name (ie typeid(int), typeid(std::string)...). To do so, I repeated in a loop the comparison of two typeid calls, and compiled it with optimizations enabled, in order to see if the compiler simplified the loop (by looking at the execution time which is 1us when it simplifies instead of 160ms when it does not). And I get strange results, because sometimes the compiler simplifies the code, and sometimes it does not. I use g++ (I tried different 4.x versions), and here is the program: #include <iostream> #include <typeinfo> #include <time.h> class DisplayData {}; class RobotDisplay: public DisplayData {}; class SensorDisplay: public DisplayData {}; class RobotQt {}; class SensorQt {}; timespec tp1, tp2; const int n = 1000000000; int main() { int avg = 0; clock_gettime(CLOCK_REALTIME, &tp1); for(int i = 0; i < n; ++i) { // if (typeid(RobotQt) == typeid(RobotDisplay)) // (1) compile time // if (typeid(SensorQt) == typeid(SensorDisplay)) // (2) compile time if (typeid(RobotQt) == typeid(RobotDisplay) || typeid(SensorQt) == typeid(SensorDisplay)) // (3) not compile time ???!!! avg++; else avg--; } clock_gettime(CLOCK_REALTIME, &tp2); std::cout << "time (" << avg << "): " << (tp2.tv_sec-tp1.tv_sec)*1000000000+(tp2.tv_nsec-tp1.tv_nsec) << " ns" << std::endl; } The conditions in which this problem appear are not clear, but: - if there is no inheritance involved, no problem (always compile time) - if I do only one comparison, no problem - the problem only appears only with a disjunction of comparisons if all the terms are false So is there something I didn't get with how typeid works (is it always supposed to be evaluated at compilation time when used with type names?) or may this be a gcc bug in evaluation or optimization? About the context, I tracked down the problem to this very simplified example, but my goal is to use typeid with template types (as partial function template specialization is not possible). Thanks for your help!

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  • Why is my Type.GetFields(BindingFlags.Instance|BindingFlags.Public) not working?

    - by granadaCoder
    My code can see the non-public members, but not the public ones. Why? FieldInfo[] publicFieldInfos = t.GetFields(BindingFlags.Instance | BindingFlags.Public); is returning nothing. Note: I'm trying to get at the properties on the abstract class as well as the concrete class. (And read the attributes as well). The MSDN example works with the 2 flags (BindingFlags.Instance | BindingFlags.Public) but my mini inheritance example below does not. private void RunTest1() { try { textBox1.Text = string.Empty; Type t = typeof(MyInheritedClass); //Look at the BindingFlags *** NonPublic *** int fieldCount = 0; while (null != t) { fieldCount += t.GetFields(BindingFlags.Instance | BindingFlags.NonPublic).Length; FieldInfo[] nonPublicFieldInfos = t.GetFields(BindingFlags.Instance | BindingFlags.NonPublic); foreach (FieldInfo field in nonPublicFieldInfos) { if (null != field) { Console.WriteLine(field.Name); } } t = t.BaseType; } Console.WriteLine("\n\r------------------\n\r"); //Look at the BindingFlags *** Public *** t = typeof(MyInheritedClass); FieldInfo[] publicFieldInfos = t.GetFields(BindingFlags.Instance | BindingFlags.Public); foreach (FieldInfo field in publicFieldInfos) { if (null != field) { Console.WriteLine(field.Name); object[] attributes = field.GetCustomAttributes(t, true); if (attributes != null && attributes.Length > 0) { foreach (Attribute att in attributes) { Console.WriteLine(att.GetType().Name); } } } } } catch (Exception ex) { ReportException(ex); } } private void ReportException(Exception ex) { Exception innerException = ex; while (innerException != null) { Console.WriteLine(innerException.Message + System.Environment.NewLine + innerException.StackTrace + System.Environment.NewLine + System.Environment.NewLine); innerException = innerException.InnerException; } } public abstract class MySuperType { public MySuperType(string st) { this.STString = st; } public string STString { get; set; } public abstract string MyAbstractString { get; set; } } public class MyInheritedClass : MySuperType { public MyInheritedClass(string ic) : base(ic) { this.ICString = ic; } [Description("This is an important property"), Category("HowImportant")] public string ICString { get; set; } private string _oldSchoolPropertyString = string.Empty; public string OldSchoolPropertyString { get { return _oldSchoolPropertyString; } set { _oldSchoolPropertyString = value; } } [Description("This is a not so importarnt property"), Category("HowImportant")] public override string MyAbstractString { get; set; } }

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  • Why is my (Type).GetFields(BindingFlags.Instance | BindingFlags.Public) not working?

    - by granadaCoder
    My code can see the NonPublic members, but not the Public ones. (???) Full sample code below. FieldInfo[] publicFieldInfos = t.GetFields(BindingFlags.Instance | BindingFlags.Public); is returning nothing. Note, I'm trying to get at the properties on the abstract class as well as the 1 concrete class. (And read the attributes as well). I'm going bonkers on this one....the msdn example works with the 2 flags (BindingFlags.Instance | BindingFlags.Public).....but my mini inheritance example below is not. THANKS in advance. /////////////START CODE private void RunTest1() { try { textBox1.Text = string.Empty; Type t = typeof(MyInheritedClass); //Look at the BindingFlags *** NonPublic *** int fieldCount = 0; while (null != t) { fieldCount += t.GetFields(BindingFlags.Instance | BindingFlags.NonPublic).Length; FieldInfo[] nonPublicFieldInfos = t.GetFields(BindingFlags.Instance | BindingFlags.NonPublic); foreach (FieldInfo field in nonPublicFieldInfos) { if (null != field) { Console.WriteLine(field.Name); } } t = t.BaseType; } Console.WriteLine("\n\r------------------\n\r"); //Look at the BindingFlags *** Public *** t = typeof(MyInheritedClass); FieldInfo[] publicFieldInfos = t.GetFields(BindingFlags.Instance | BindingFlags.Public); foreach (FieldInfo field in publicFieldInfos) { if (null != field) { Console.WriteLine(field.Name); object[] attributes = field.GetCustomAttributes(t, true); if (attributes != null && attributes.Length > 0) { foreach (Attribute att in attributes) { Console.WriteLine(att.GetType().Name); } } } } } catch (Exception ex) { ReportException(ex); } } private void ReportException(Exception ex) { Exception innerException = ex; while (innerException != null) { Console.WriteLine(innerException.Message + System.Environment.NewLine + innerException.StackTrace + System.Environment.NewLine + System.Environment.NewLine); innerException = innerException.InnerException; } } public abstract class MySuperType { public MySuperType(string st) { this.STString = st; } public string STString { get; set; } public abstract string MyAbstractString {get;set;} } public class MyInheritedClass : MySuperType { public MyInheritedClass(string ic) : base(ic) { this.ICString = ic; } [Description("This is an important property"),Category("HowImportant")] public string ICString { get; set; } private string _oldSchoolPropertyString = string.Empty; public string OldSchoolPropertyString { get { return _oldSchoolPropertyString; } set { _oldSchoolPropertyString = value; } } [Description("This is a not so importarnt property"), Category("HowImportant")] public override string MyAbstractString { get; set; } }

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  • Encapsulating a Windows.Forms.Button

    - by devoured elysium
    I want to define a special kind of button that only allows two possible labels: "ON" and "OFF". I decided to inherit from a Windows.Forms.Button to implement this but now I don't know I how should enforce this rule. Should I just override the Text property like this? public override string Text { set { throw new InvalidOperationException("Invalid operation on StartStopButton!"); } } The problem I see with this is that I am breaking the contract that all buttons should have. If any code tries something like foreach (Button button in myForm) { button.Text = "123"; } they will get an Exception if I have any of my special buttons on the form, which is something that isn't expectable. First, because people think of properties just as "public" variables, not methods, second, because they are used to using and setting whatever they want to buttons without having to worry with Exceptions. Should I instead just make the set property do nothing? That could also lead to awkward results: myButton.Text = "abc"; MessageBox.Show(abc); //not "abc"! The general idea from the OO world is to in this kind of cases use Composition instead of inheritance. public class MySpecialButton : <Some class from System.Windows.Forms that already knows how to draw itself on forms> private Button button = new Button(); //I'd just draw this button on this class //and I'd then only show the fields I consider //relevant to the outside world. ... } But to make the Button "live" on a form it must inherit from some special class. I've looked on Control, but it seems to already have the Text property defined. I guess the ideal situation would be to inherit from some kind of class that wouldn't even have the Text property defined, but that'd have position, size, etc properties available. Upper in the hierarchy, after Control, we have Component, but that looks like a really raw class. Any clue about how to achieve this? I know this was a long post :( Thanks

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