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  • Namespace constraint with generic class decleration

    - by SomeGuy
    Good afternoon people, I would like to know if (and if so how) it is possible to define a namespace as a constraint parameter in a generic class declaration. What I have is this: namespace MyProject.Models.Entities <-- Contains my classes to be persisted in db namespace MyProject.Tests.BaseTest <-- Obvious i think Now the decleration of my 'BaseTest' class looks like so; public class BaseTest<T> This BaseTest does little more (at the time of writing) than remove all entities that were added to the database during testing. So typically I will have a test class declared as: public class MyEntityRepositoryTest : BaseTest<MyEntity> What i would LIKE to do is something similar to the following: public class BaseTest<T> where T : <is of the MyProject.Models.Entities namespace> Now i am aware that it would be entirely possible to simply declare a 'BaseEntity' class from which all entities created within the MyProject.Models.Entities namespace will inherit from; public class BaseTest<T> where T : MyBaseEntity but...I dont actually need to, or want to. Plus I am using an ORM and mapping entities with inheritance, although possible, adds a layer of complexity that is not required. So, is it possible to constrain a generic class parameter to a namespace and not a specific type ? Thank you for your time.

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  • c++-to-python swig caused memory leak! Related to Py_BuildValue and SWIG_NewPointerObj

    - by usfree74
    Hey gurus, I have the following Swig code that caused memory leak. PyObject* FindBestMatch(const Bar& fp) { Foo* ptr(new Foo()); float match; // call a function to fill the foo pointer return Py_BuildValue( "(fO)", match, SWIG_NewPointerObj(ptr, SWIGTYPE_p_Foo, 0 /* own */)); } I figured that ptr is not freed properly. So I did the following: PyObject* FindBestMatch(const Bar& fp) { Foo* ptr(new Foo()); float match; // call a function to fill the foo pointer *PyObject *o = SWIG_NewPointerObj(ptr, SWIGTYPE_p_Foo, 1 /* own */);* <------- 1 means pass the ownership to python PyObject *result = Py_BuildValue("(fO)", match, o); Py_XDECREF(o); return result; } But I am not very sure whether this will cause memory corruption. Here, Py_XDECREF(o) will decrease the ref count, which can free memory used by object "o". But o is part of the return value "result". Freeing "o" can cause data corrupt, I guess? I tried my change. It works fine and the caller (python code) does see the expected data. But this could be because nobody else overwrites to that memory area. So what's the right way to deal with memory management of the above code? I search the swig docs, but don't see very concrete description. Please help! Thanks, xin

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  • OOP, Interface Design and Encapsulation

    - by Mau
    C# project, but it could be applied to any OO languages. 3 interfaces interacting: public interface IPublicData {} public /* internal */ interface IInternalDataProducer { string GetData(); } public interface IPublicWorker { IPublicData DoWork(); IInternalDataProducer GetInternalProducer(); } public class Engine { Engine(IPublicWorker worker) {} IPublicData Run() { DoSomethingWith(worker.GetInternalProducer().GetData()); return worker.DoWork(); } } Clearly Engine is parametric in the actual worker that does the job. A further source of parametrization is how we produce the 'internal data' via IInternalDataProducer. This implementation requires IInternalDataProducer to be public because it's part of the declaration of the public interface IPublicWorker. However, I'd like it to be internal since it's only used by the engine. A solution is make the IPublicWorker produce the internal data itself, but that's not very elegant since there's only a couple of ways of producing it (while there are many more worker implementations), therefore it's nice to delegate to a couple of separate concrete classes. Moreover, the IInternalDataProducer is used in more places inside the engine, so it's good for the engine to pass around the actual object. I'm looking for elegant ideas/patterns. Cheers :-)

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  • Can't add to NSMutableArray from SecondaryView

    - by Antonio
    Hi guys, I've searched and read and still haven't found a concrete answer. Brief: I have an application where I declare an NSMutableArray in my AppDelegate to synthesize when the application loads. (code below). I have a SecondaryViewController call this function, and I have it output a string to let me know what the array size is. Every time I run it, it executes but it does not add any objects to the array. How do I fix this? AppDelegate.h file #import <UIKit/UIKit.h> @class arrayTestViewController; @interface arrayTestAppDelegate : NSObject <UIApplicationDelegate> { UIWindow *window; arrayTestViewController *viewController; NSMutableArray *myArray3; } @property (nonatomic, retain) NSMutableArray *myArray3; @property (nonatomic, retain) IBOutlet UIWindow *window; @property (nonatomic, retain) IBOutlet arrayTestViewController *viewController; -(void)addToArray3; @end AppDelegate.m file #import "arrayTestAppDelegate.h" #import "arrayTestViewController.h" @implementation arrayTestAppDelegate @synthesize window; @synthesize viewController; @synthesize myArray3; #pragma mark - #pragma mark Application lifecycle - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { myArray3 = [[NSMutableArray alloc] init]; // Override point for customization after application launch. // Add the view controller's view to the window and display. [window addSubview:viewController.view]; [window makeKeyAndVisible]; return YES; } -(void)addToArray3{ NSLog(@"Array Count: %d", [myArray3 count]); [myArray3 addObject:@"Test"]; NSLog(@"Array triggered from SecondViewController"); NSLog(@"Array Count: %d", [myArray3 count]); } SecondViewController.m file #import "SecondViewController.h" #import "arrayTestAppDelegate.h" @implementation SecondViewController -(IBAction)addToArray{ arrayTestAppDelegate *object = [[arrayTestAppDelegate alloc] init]; [object addToArray3]; }

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  • Abstract factory pattern on top of IoC?

    - by Sergei
    I have decided to use IoC principles on a bigger project. However, i would like to get something straight that's been bothering me for a long time. The conclusion that i have come up with is that an IoC container is an architectural pattern, not a design pattern. In other words, no class should be aware of its presence and the container itself should be used at the application layer to stitch up all components. Essentially, it becomes an option, on top of a well designed object-oriented model. Having said that, how is it possible to access resolved types without sprinkling IoC containers all over the place (regardless of whether they are abstracted or not)? The only option i see here is to utilize abstract factories which use an IoC container to resolve concrete types. This should be easy enough to swap out for a set of standard factories. Is this a good approach? Has anyone on here used it and how well did it work for you? Is there anything else available? Thanks!

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  • How to create a platform ontop of CSLA? <-- if in case it make sense

    - by Peejay
    Hi all! here is the senario, i'm developing an application using csla 3.8 / c#.net, the application will have different modules. its like an ERP, it will have accounting, daily time record, recruitment etc as modules. Now the requirement is to check for common entities per module and build a "platform" (<- the boss calls it that way) from it. for example, DTR will have an entity "employee", Recruitment will have "Applicant" so one common entity that you can derive from both that can be put in the platform is "Person". "Person" will contain typical info like name, address, contact info etc. I know it sounds like OOP 101. the thing is, i dont know how i am to go about it. how i wish it was just a simple inheritance but the requirement is like to create an API of some sort to be used by the modules using CSLA. in csla you create smart objects right, inheriting from the base classes of csla like businessListbase, readonlylistbase etc. right? what if for example i created a businessbase Applicant class, it will have properties like salary demand, availability date etc. now for the personal info i will need the "Person" from the "platform" and implement it to the applicant class. so in summary i have several questions: how to create such platform? if such platform is possible, how will it be implemented on each module's entities? (im already inheriting from base clases of csla) if incase 1 and 2 are possible, does it have advantages on development and maintenace of the app? the reason why i'm asking #3 is because the way i see it, even if i am able to create a platform for that, i will be needing to define properties of the platform entity on my module entities so to have validation and all. im sorry if i'm typing nonesense i'm really confused. hope someone could enlighten me. thank you all!

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  • Ember Data Sycn - LocalStorage+REST+RealTime+Online/Offline

    - by Miguel Madero
    We have a combination of requirements in terms o data access. Pre-load some reference data. We need reference data to survive browser restarts instead of just living in memory to avoid loading it all the time. I'm currently using the LocalStorageAdapter for that. Once we have it, we would like to sync changes (polling or using Socket.IO in the background and updating the LocalStorage could do the trick) There're other models that are more transactional, where we would need to directly go to the Server and get/save them. It would be nice to use something like the RESTAdapter for that. Lastly, there're some operations that should work off-line and changes should be synced later. To make it more concrete: * We pre-load vendor and "favorite products" into Local Storage. We work offline with those. * We need to sync server changes to vendor and product information. * If they search the full catalog, that requires them to be online. * When offline, we need to allow users to add something to their cart or even submit and order. We would like to queue this action and submit it when they have an Internet Connection. So a few questions are derived from this: * Is there a way to user RESTAdapter in combination with LocalStorage? * Is there some Socket.IO support? (Happy to do this part manually) * Is there Queueing support? Ideally at the Ember-Data level. I know we will have to do a lot of this manually and pull together the different lego pieces, but I wanted to ask for some perspective from experience Ember devs.

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  • Use of 'super' keyword when accessing non-overridden superclass methods

    - by jonny
    I'm trying to get the hang of inheritance in Java and have learnt that when overriding methods (and hiding fields) in sub classes, they can still be accessed from the super class by using the 'super' keyword. What I want to know is, should the 'super' keyword be used for non-overridden methods? Is there any difference (for non-overridden methods / non-hidden fields)? I've put together an example below. public class Vehicle { public int tyreCost; public Vehicle(int tyreCost) { this.tyreCost = tyreCost; } public int getTyreCost() { return tyreCost; } } and public class Car extends Vehicle { public int wheelCount; public Vehicle(int tyreCost, int wheelCount) { super(tyreCost); this.wheelCount = wheelCount; } public int getTotalTyreReplacementCost() { return getTyreCost() * wheelCount; } } Specifically, given that getTyreCost() hasn't been overridden, should getTotalTyreReplacementCost() use getTyreCost(), or super.getTyreCost() ? I'm wondering whether super should be used in all instances where fields or methods of the superclass are accessed (to show in the code that you are accessing the superclass), or only in the overridden/hidden ones (so they stand out).

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  • SQL Server error handling: exceptions and the database-client contract

    - by gbn
    We’re a team of SQL Servers database developers. Our clients are a mixed bag of C#/ASP.NET, C# and Java web services, Java/Unix services and some Excel. Our client developers only use stored procedures that we provide and we expect that (where sensible, of course) they treat them like web service methods. Some our client developers don’t like SQL exceptions. They understand them in their languages but they don’t appreciate that the SQL is limited in how we can communicate issues. I don’t just mean SQL errors, such as trying to insert “bob” into a int column. I also mean exceptions such as telling them that a reference value is wrong, or that data has already changed, or they can’t do this because his aggregate is not zero. They’d don’t really have any concrete alternatives: they’ve mentioned that we should output parameters, but we assume an exception means “processing stopped/rolled back. How do folks here handle the database-client contract? Either generally or where there is separation between the DB and client code monkeys. Edits: we use SQL Server 2005 TRY/CATCH exclusively we log all errors after the rollback to an exception table already we're concerned that some of our clients won't check output paramaters and assume everything is OK. We need errors flagged up for support to look at. everything is an exception... the clients are expected to do some message parsing to separate information vs errors. To separate our exceptions from DB engine and calling errors, they should use the error number (ours are all 50,000 of course)

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  • jQuery or CSS - How do you make a link in a table row appear underlined even when the cursor is in a

    - by adam
    I have a table of 3-4 columns, the central one being task names that are also links(yet another todo app..groan). Im trying to make it so that whenever the mouse hovers over any part of the table row - not just the link itself - the link will appear underlined. Its a small detail but its been annoying me like hell and i refuse to let it get the better of me now. At first i tried jQuery with a (forgive the obvious syntax errors but this is the jist) $('#row_in_question').hover( function(){ $(this).find(...the link..).toggleClass("highlighted") }, function(){ $(this).find(...the link..).toggleClass("highlighted") } ); with this as a styling for the a element in general .highlighted { text-decoration: underlined; } and it did indeed toggle the highlighted class on that link - however css inheritance got in the way and no visual changes made. Since i previously styled that link to have no underline when not hovered it wouldnt change the style. So how do i go about this? I dont want the whole row to become clickable, I just want the text to become underlined.

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  • BinaryFormatter in C# a good way to read files?

    - by mr-pac
    I want to read a binary file which was created outside of my program. One obvious way in C# to read a binary file is to define class representing the file and then use a BinaryReader and read from the file via the Read* methods and assign the return values to the class properties. What I don't like with the approach is that I manually have to write code that reads the file, although the defined structure represents how the file is stored. I also have to keep the order correct when I read. After looking a bit around I came across the BinaryFormatter which can automatically serialize and deserialze object in binary format. One great advantage would be that I can read and also write the file without creating additional code. However I wonder if this approach is good for files created from other programs on not just serialized .NET objects. Take for example a graphics format file like BMP. Would it be a good idea to read the file with a BinaryFormatter or is it better to manually and write via BinaryReader and BinaryWriter? Or are there any other approaches which suit better? I'am not looking for concrete examples but just for an advice what is the best way to implement that.

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  • Is .NET 4.0 just a show?

    - by Will Marcouiller
    I went to a presentation about the .NET Framework and Visual Studio 2010, last night. The topis were: ASP.NET 4 - Some of the new features of ASP.NET 4 More control over ClientID's in WebForms; Output Caching; ... // Some other stuff I don't really remember being more in framework and WinForms world. Entity Framework 2.0 (.NET 4.0) T4 Templates; Domain driven development; Data driven development; Contexts (edmx files); Some of real-world limitations of EF4 (projects with over 70 to 75 tables); Better POCO support, despite there are still these hidden EntityObject and StructuralObject, but used differently in comparison to EF 1.0 so that it doesn't take off your inheritance; Allows to easily choose how to persist the hierarchy into the underlying database; Code only (start working with EF4 directly from your code!); Design by Contract (DbC). The most interesting feature is, and only, as far as I'm concerned, all related to parallelism made easier. Which really works! No additional assembly references to add. In conclusion, I'm far from impressed about .NET Framework 4.0, apart that it makes some things easier to do. But when you're used to make it a way, it doesn't really change much, in my opinion. Is it me who cannot foresee what .NET 4.0 has to offer? What would you guys base your decision on to migrate to .NET 4.0, in a practical way?

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  • JAXB code generation: how to remove a zero occurrence field?

    - by reef
    Hi all, I use JAXB 2.1 to generate Java classes from several XSD files, and I have a problem related to complex type restriction. On of the restrictions modifies the occurence configuration from minOccurs="0" maxOccurs="unbounded" to minOccurs="0" maxOccurs="0". Thus this field is not needed anymore in the restricted type. But actually JAXB generates the restricted class with a [0..1] cardinality instead of 0. By the way the generation is tuned with <xjc:treatRestrictionLikeNewType / so that a XSD restriction is not mapped to a Java class inheritance. Here is an example: Here is the way a field is defined in a complex type A: <element name="qualifier" type="CR" maxOccurs="unbounded" minOccurs="0"/ Here is the way the same field is restricted in another complex type B that restricts A: <element name="qualifier" type="CR" minOccurs="0" maxOccurs="0"/ In the A generated class I have: @XmlElement(name = "qualifier") protected List<CR qualifiers; And in the B generated class I have: protected CR qualifiers; With my poor understanding of JAXB the absence of the XmlElement annotation tells JAXB not to marshall/unmarshall this field. Am I wrong? If I am right is there a way to tell JAXB not to generate the qualifiers field at all? This would be in my opinion a much better generation as it respects the constraints. Any idea, thougths on the topic? Thanks!!

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  • How to pass data to a C++0x lambda function that will run in a different thread?

    - by Dimitri C.
    In our company we've written a library function to call a function asynchronously in a separate thread. It works using a combination of inheritance and template magic. The client code looks as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, &DemoThread::SomeFunction, stringToPassByValue); Since the introduction of lambda functions I'd like to use it in combination with lambda functions. I'd like to write the following client code: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=]() { const std::string someCopy = stringToPassByValue; }); Now, with the Visual C++ 2010 this code doesn't work. What happens is that the stringToPassByValue is not copied. Instead the "capture by value" feature passes the data by reference. The result is that if the function is executed after stringToPassByValue has gone out of scope, the application crashes as its destructor is called already. So I wonder: is it possible to pass data to a lambda function as a copy? Note: One possible solution would be to modify our framework to pass the data in the lambda parameter declaration list, as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=](const std::string stringPassedByValue) { const std::string someCopy = stringPassedByValue; } , stringToPassByValue); However, this solution is so verbose that our original function pointer solution is both shorter and easier to read. Update: The full implementation of AsyncCall is too big to post here. In short, what happens is that the AsyncCall template function instantiates a template class holding the lambda function. This class is derived from a base class that contains a virtual Execute() function, and upon an AsyncCall() call, the function call class is put on a call queue. A different thread then executes the queued calls by calling the virtual Execute() function, which is polymorphically dispatched to the template class which then executes the lambda function.

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  • Is it poor design to create objects that only execute code during the constructor?

    - by Curtix
    In my design I am using objects that evaluate a data record. The constructor is called with the data record and type of evaluation as parameters and then the constructor calls all of the object's code necessary to evaluate the record. This includes using the type of evaluation to find additional parameter-like data in a text file. There are in the neighborhood of 250 unique evaluation types that use the same or similar code and unique parameters coming from the text file. Some of these evaluations use different code so I benefit a lot from this model because I can use inheritance and polymorphism. Once the object is created there isn't any need to execute additional code on the object (at least for now) and it is used more like a struct; its kept on a list and 3 properties are used later. I think this design is the easiest to understand, code, and read. A logical alternative I guess would be using functions that return score structs, but you can't inherit from methods so it would make it kind of sloppy imo. I am using vb.net and these classes will be used in an asp.net web app as well as in a distributed app. thanks for your input

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  • Improve this generic abstract class

    - by Keivan
    I have the following abstract class design, I was wondering if anyone can suggest any improvements in terms of stronger enforcement of our requirements or simplifying implementing of the ControllerBase. //Dependency Provider base public abstract class ControllerBase<TContract, TType> where TType : TContract, class { public static TContract Instance { get { return ComponentFactory.GetComponent<TContract, TType>(); } } public TContract GetComponent<TContract, TType>() where TType : TContract, class { component = (TType)Activator.CreateInstance(typeof(TType), true); RegisterComponentInstance<TContract>(component); } } //Contract public interface IController { void DoThing(); } //Actual Class Logic public class Controller: ControllerBase<IController,Controller> { public void DoThing(); //internal constructor internal Controller(){} } //Usage public static void Main() { Controller.Instance.DoThing(); } The following facts should always be true, TType should always implement TContract (Enforced using a generic constraint) TContract must be an interface (Can't find a way to enforce it) TType shouldn't have public constructor, just an internal one, is there any way to Enforce that using ControllerBase? TType must be an concrete class (Didn't include New() as a generic constrain since the constructors should be marked as Internal)

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  • Mocking non-virtual methods in C++ without editing production code?

    - by wk1989
    Hello, I am a fairly new software developer currently working adding unit tests to an existing C++ project that started years ago. Due to a non-technical reason, I'm not allowed to modify any existing code. The base class of all my modules has a bunch of methods for Setting/Getting data and communicating with other modules. Since I just want to unit testing each individual module, I want to be able to use canned values for all my inter-module communication methods. I.e. for a method Ping() which checks if another module is active, I want to have it return true or false based on what kind of test I'm doing. I've been looking into Google Test and Google Mock, and it does support mocking non-virtual methods. However the approach described (http://code.google.com/p/googlemock/wiki/CookBook#Mocking_Nonvirtual_Methods) requires me to "templatize" the original methods to take in either real or mock objects. I can't go and templatize my methods in the base class due to the requirement mentioned earlier, so I need some other way of mocking these virtual methods Basically, the methods I want to mock are in some base class, the modules I want to unit test and create mocks of are derived classes of that base class. There are intermediate modules in between my base Module class and the modules that I want to test. I would appreciate any advise! Thanks, JW EDIT: A more concrete examples My base class is lets say rootModule, the module I want to test is leafModule. There is an intermediate module which inherits from rootModule, leafModule inherits from this intermediate module. In my leafModule, I want to test the doStuff() method, which calls the non virtual GetStatus(moduleName) defined in the rootModule class. I need to somehow make GetStatus() to return a chosen canned value. Mocking is new to me, so is using mock objects even the right approach?

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  • CreateProcess() fails with an access violation

    - by John Doe
    My aim is to execute an external executable in my program. First, I used system() function, but I don't want the console to be seen to the user. So, I searched a bit, and found CreateProcess() function. However, when I try to pass a parameter to it, I don't know why, it fails. I took this code from MSDN, and changed a bit: #include <windows.h> #include <stdio.h> #include <tchar.h> void _tmain( int argc, TCHAR *argv[] ) { STARTUPINFO si; PROCESS_INFORMATION pi; ZeroMemory( &si, sizeof(si) ); si.cb = sizeof(si); ZeroMemory( &pi, sizeof(pi) ); /* if( argc != 2 ) { printf("Usage: %s [cmdline]\n", argv[0]); return; } */ // Start the child process. if( !CreateProcess( NULL, // No module name (use command line) L"c:\\users\\e\\desktop\\mspaint.exe", // Command line NULL, // Process handle not inheritable NULL, // Thread handle not inheritable FALSE, // Set handle inheritance to FALSE 0, // No creation flags NULL, // Use parent's environment block NULL, // Use parent's starting directory &si, // Pointer to STARTUPINFO structure &pi ) // Pointer to PROCESS_INFORMATION structure ) { printf( "CreateProcess failed (%d).\n", GetLastError() ); return; } // Wait until child process exits. WaitForSingleObject( pi.hProcess, INFINITE ); // Close process and thread handles. CloseHandle( pi.hProcess ); CloseHandle( pi.hThread ); } However, this code crated access violation somehow. Can I execute mspaint without showing user the console? Thank you very much.

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  • S3 file Uploading from Mac app though PHP?

    - by Ilija Tovilo
    I have asked this question before, but it was deleted due too little information. I'll try to be more concrete this time. I have an Objective-C mac application, which should allow users to upload files to S3-storage. The s3 storage is mine, the users don't have an Amazon account. Until now, the files were uploaded directly to the amazon servers. After thinking some more about it, it wasn't really a great concept, regarding security and flexibility. I want to add a server in between. The user should authenticate with my server, the server would open a session if the authentication was successful, and the file-sharing could begin. Now my question. I want to upload the files to S3. One option would be to make a POST-request and wait until the server would receive the file. Problems here are, that there would be a delay, when the file is being uploaded from my server to the S3 servers, and it would double the uploading time. Best would be, if I could validate the request, and then redirecting it, so the client uploads it directly to the s3-storage. Not sure if this is possible somehow. Uploading directly to S3 doesn't seem to be very smart. After looking into other apps like Droplr and Dropmark, it looks like they don't do this. Btw. I did this using Little Snitch. They have their api on their own web-server, and that's it. Could someone clear things up for me? EDIT How should I transmit my files to S3? Is there a way to "forward" it, or do I have to upload it to my server and then upload it from there to S3? Like I said, other apps can do this efficiently and without the need of communicating with S3 directly.

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  • On the search for my next great .Net Read

    - by user127954
    Just got done with "The art of unit testing". It was a great read and i think everyone should go buy a copy. With that said i think the next book I'm like to read would be a architecture / Design type book that would focus heavily on building your objects / software in such a way that it would be: Low Coupling High Cohesion Easily Maintainable / Extended Easy to test Easy to Navigate / Debug The above characteristcs are the most important ones but also maybe it would also include (but not necessary) designing for: Performance - Don't want to design a system at at the end find out its dog slow :) Scalability - Again don't want to design something at the end find out it won't scale. I'd also prefer (but not necessary again): Something newer - Architectural principles seem to gradually evolve / improve over time and id like something with current thinking. .Net as illustrating language - like i said above its not mandatory but since its what i use every day id prefer it to be in .net. Doesn't really matter if its in vb.net or c# Some of the topics that would be talked about its how to minimize dependencies and using interfaces throughout your solution rather than concrete classes. Maybe it would constract /compare some of the newest design principles like DDD, Repository Pattern, Ect... I already have "Clean Code" (don't know if its this type of book or not) and "Working effectively with legacy code" on my radar but id like to read a book based upon the topic i talked about above first. Is there such a book?

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  • Open closed prinicple, problem

    - by Marcus
    Hi, I'm trying to apply OCP to a code snippet I have that in it's current state is really smelly, but I feel I'm not getting all the way to the end. Current code: public abstract class SomeObject {} public class SpecificObject1 : SomeObject {} public class SpecificObject2 : SomeObject {} // Smelly code public class Model { public void Store(SomeObject someObject) { if (someObject is SpecificObject1) {} else if (someObject is SpecificObject2) {} } } That is really ugly, my new approach looks like this: // No so smelly code public class Model { public void Store(SomeObject someObject) { throw new Expception("Not allowed!"); } public void Store(SpecificObject1 someObject) {} public void Store(SpecificObject2 someObject) {} } When a new SomeObject type comes along I must implement how that specific object is stored, this will break OCP cause I need to alter the Model-class. To move the store logic to SomeObject also feels wrong cause then I will violate SRP (?), becuase in this case the SomeObject is almost like a DTO, it's resposibility it not how to know to store itself. If a new implementation to SomeObject comes along who's store implementation is missing I will get a runtime error due to exception in Store method in Model class, it also feels like a code smell. This is because calling code will in the form of IEnumerable<SomeObject> sequence; I will not know the specific types of the sequence objects. I can't seem to grasp the OCP-concept. Anyone has any concrete examples or links that is a bit more than just some Car/Fruit example?

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  • Ninject: How do I inject into a class library ?

    - by DennyDotNet
    To start I'm using Ninject 1.5. I have two projects: Web project and a Class library. My DI configuration is within the Web project. Within my class library I have the following defined: public interface ICacheService<T> { string Identifier { get; } T Get(); void Set( T objectToCache, TimeSpan timeSpan ); bool Exists(); } And then a concrete class called CategoryCacheService. In my web project I bind the two: Bind( typeof( ICacheService<List<Category>> ) ).To( typeof(CategoryCacheService)).Using<SingletonBehavior>(); In my class library I have extension methods for the HtmlHelper class, for example: public static class Category { [Inject] public static ICacheService Categories { get; set; } public static string RenderCategories(this HtmlHelper htmlHelper) { var c = Categories.Get(); return string.Join(", ", c.Select(s = s.Name).ToArray()); } } I've been told that you cannot inject into static properties, instead I should use Kernel.Get<() - However... Since the code above is in a class library I don't have access to the Kernel. How can I get the Kernel from this point or is there a better way of doing this? Thanks!

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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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  • 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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  • C++ design related question

    - by Kotti
    Hi! Here is the question's plot: suppose I have some abstract classes for objects, let's call it Object. It's definition would include 2D position and dimensions. Let it also have some virtual void Render(Backend& backend) const = 0 method used for rendering. Now I specialize my inheritance tree and add Rectangle and Ellipse class. Guess they won't have their own properties, but they will have their own virtual void Render method. Let's say I implemented these methods, so that Render for Rectangle actually draws some rectangle, and the same for ellipse. Now, I add some object called Plane, which is defined as class Plane : public Rectangle and has a private member of std::vector<Object*> plane_objects; Right after that I add a method to add some object to my plane. And here comes the question. If I design this method as void AddObject(Object& object) I would face trouble like I won't be able to call virtual functions, because I would have to do something like plane_objects.push_back(new Object(object)); and this should be push_back(new Rectangle(object)) for rectangles and new Circle(...) for circles. If I implement this method as void AddObject(Object* object), it looks good, but then somewhere else this means making call like plane.AddObject(new Rectangle(params)); and this is generally a mess because then it's not clear which part of my program should free the allocated memory. ["when destroying the plane? why? are we sure that calls to AddObject were only done as AddObject(new something).] I guess the problems caused by using the second approach could be solved using smart pointers, but I am sure there have to be something better. Any ideas?

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