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• C# DLL reference changes version and becomes unloadable (Plugin-system)

  - by Kristoffer

  I will try to keep this as simple as possible. I have a rather simple plugin system that has run into a problem. I have 2 assemblies: Host.exe Plugin.dll Plugin.dll references Host.exe (which contains interfaces and classes that Plugin.dll implement and use). At runtime, Host.exe loads Plugin.dll through reflection and this works great. Except when Host.exe updates and gets a new version number. Then I get an error once I try to load Plugin.dll, saying that Host.exe (with the old version number) can't be found. This means I have to rebuild all plugins every time Host.exe changes build number. Anyone got a solution to this?

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• User Interface functionality modelling languages?

  - by naugtur

  I am looking for a UI functionality modelling language (UML-alike "thing", but for user interfaces) that is already accepted and maybe has its design patterns and handles the problem better than state or activity diagram. (If there is no such thing I'm planning to develop that BTW :)) This question came to mind as a result of a discovery that UML and its diagrams fails at describing complicated UI functionality with event-driven flow of execution (ie. javascript/jQuery big projects) EDIT: I've been thinking of using BPMN but It was not created for this purpose. EDIT2: See this community topic of mine - I decided to start developing said language.

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• Which method should I use ?

  - by Ivan

  I want to do this exercise but I don't know exactly which method should I use for an exercise like this and what data will I use to test the algorithm. The driving distance between Perth and Adelaide is 1996 miles. On the average, the fuel consumption of a 2.0 litre 4 cylinder car is 8 litres per 100 kilometres. The fuel tank capacity of such a car is 60 litres. Design and implement a JAVA program that prompts for the fuel consumption and fuel tank capacity of the aforementioned car. The program then displays the minimum number of times the car’s fuel tank has to be filled up to drive from Perth to Adelaide. Note that 62 miles is equal to 100 kilometres. What data will you use to test that your algorithm works correctly?

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• Views performance in MySQL

  - by Gianluca Bargelli

  I am currently writing my truly first PHP Application and i would like to know how to project/design/implement MySQL Views properly; In my particular case User data is spread across several tables (as a consequence of Database Normalization) and i was thinking to use a View to group data into one large table: CREATE VIEW `Users_Merged` ( name, surname, email, phone, role ) AS ( SELECT name, surname, email, phone, 'Customer' FROM `Customer` ) UNION ( SELECT name, surname, email, tel, 'Admin' FROM `Administrator` ) UNION ( SELECT name, surname, email, tel, 'Manager' FROM `manager` ); This way i can use the View's data from the PHP app easily but i don't really know how much this can affect performance. For example: SELECT * from `Users_Merged` WHERE role = 'Admin'; Is the right way to filter view's data or should i filter BEFORE creating the view itself? (I need this to have a list of users and the functionality to filter them by role).

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• Is testability alone justification for dependency injection?

  - by fearofawhackplanet

  The advantages of DI, as far as I am aware, are: Reduced Dependencies More Reusable Code More Testable Code More Readable Code Say I have a repository, OrderRepository, which acts as a repository for an Order object generated through a Linq to Sql dbml. I can't make my orders repository generic as it performs mapping between the Linq Order entity and my own Order POCO domain class. Since the OrderRepository by necessity is dependent on a specific Linq to Sql DataContext, parameter passing of the DataContext can't really be said to make the code reuseable or reduce dependencies in any meaningful way. It also makes the code harder to read, as to instantiate the repository I now need to write new OrdersRepository(new MyLinqDataContext()) which additionally is contrary to the main purpose of the repository, that being to abstract/hide the existence of the DataContext from consuming code. So in general I think this would be a pretty horrible design, but it would give the benefit of facilitating unit testing. Is this enough justification? Or is there a third way? I'd be very interested in hearing opinions.

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• An unhandled exception of type 'System.StackOverflowException' occurred in mscorlib.dll

  - by Sahar

  Hello everybody i wrote a code in asp.net that read data from files and draw a graph. It worked but after awhile when i run the program, this exception arise "An unhandled exception of type 'System.StackOverflowException' occurred in mscorlib.dll" in this statement in the code: if (File.Exists(fName)) <----(here is the exception) { stream = File.Open(fName, FileMode.Open); g_day = Deserialize(stream); stream.Close(); int cn = 0; if (g_day.Values.Count != 0) cn = g_day.Values[g_day.Values.Count - 1].Value; Label1.Text = cn.ToString(); } can u help me

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• Synchronising scripts / db / files from dev system to web server

  - by Spoonface

  I work as a freelance web dev, and up until now have been ftping my scripts / databases / static files to my web server manually, but I'm finding that is too error prone. So I'm looking for an app to automate uploading new and updated scripts / files / databases / etc. I know a lot of independent devs use WinSCP or Unison, but I don't think those apps can synch databases. Does anyone have any other suggestions? It doesn't need to be anything overly feature rich as I'm not working within a team or across multiple operating systems or anything like that. I can purchase any reasonably priced license if necesary. My work is primarily for PHP / MySQL / Apache on a Windows system, and then uploaded to a Linux / Apache server. thanks for your time!

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• State pattern: Why doesn't the context class implement or inherit the State abstract interface/class

  - by Ricket

  I'm reading about the State pattern. I have only just begun, so of course I begin by reading the entire Wikipedia article on it. I noticed that both of the examples in the article have some base abstract class or Java interface for a generic State's methods/functions. Then there are some states which inherit from the base and implement those methods/functions in different ways. Then there's a Context class which has a private member of type State and which, at any time, can be equal to an instance of one of the implementations. That context class also implements the same methods, and passes them onto the current state instance, and then has an additional method to change the state (or depending on design I understand the change of state could be a reaction to one of the implemented methods). Why doesn't this context class specifically "extend" or "implement" the generic State base class/interface?

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• How does operating system software maintains time clocks?

  - by Neeraj

  Hi everyone, This may sound a bit less relevant but I couldn't think of a better place to ask this question. Now consider this situation, you install an OS on your system, set the timezone and time, do some stuff and turn it off. (Note that there is no power going in to the computer). Now next time (say after some hours or days) you turn it on again, and you see the updated time. How is this possible even when my computer is not connected to the internet and was consuming no power during the period it was down.(Is there some kind of hardware hack?) please clarify!

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• Ordering the calling of asynchronous methods in c#

  - by Peter Kelly

  Hi, Say I have 4 classes ControllerClass MethodClass1 MethodClass2 MethodClass3 and each MethodClass has an asynchronous method DoStuff() and each has a CompletedEvent. The ControllerClass is responsible for invoking the 3 asynchronous methods on the 3 MethodClasses in a particular order. So ControllerClass invokes MethodClass1.DoStuff() and subscribes to MethodClass1.CompletedEvent. When that event is fired, ControllerClass invokes MethodClass2.DoStuff() and subscribes to MethodClass2.CompletedEvent. When that event is fired, the ControllerClass invokes MethodClass3.DoStuff() Is there a best practice for a situation like this? Is this bad design? I believe it is because I am finding it hard to unit test (a sure sign) It is not easy to change the order I have an uneasy, code-smell feeling about it What are the alternatives in a situation like this?

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• How do you keep yourself and your co-workers from creating huge classes

  - by PieterG

  Stackoverflow users, How do you keep yourself from creating large classes with large bodied methods. When deadlines are tight, you end up trying to hack things together and it ends up being a mess which would need to be refactored. For me, the one way was to start with test driven development and that lends itself to good class design as well as the SRP (Single Responsibility Principle). I also see developers just double clicking on controls and typing out line after line in the event method that gets fired. What are your suggestions?

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• Unable to convert MySQL date/time value to System.DateTime

  - by Sri Kumar

  Hello I am using ibatis and C#. i get a result from a select query that has CreatedDate as one of the field. The Datatype of CreatedDate in Mysql is Date. I assign the result set of the select query to a Ilist< DeliveryClass **. Here the DeliveryClass CreatedDate as DateTime. When i run the application, i get **Unable to convert MySQL date/time value to System.DateTime. What could be the problem?

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• Java WebApp - Integrate a Payment method system

  - by spike07

  I've a java webApp where people can sell their items like in ebay. I need to integrate a payment system and I'm wondering what's the best (from a customer point of view) and easiest to integrate in my app. I was thinking to integrate paypal and require all the sellers to have an account on it. Maybe Google Checkout can be a good option as well, but I don't know if it's used a lot. I think I'll redirect the user to Paypal and then remove the item once I receive the confirmation from paypal that the item has been payed. Would you suggest another easier to integrate/more trusted solution? Thank you

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• Separate functionality depending on Role in ASP.NET MVC

  - by Andrew Bullock

  I'm looking for an elegant pattern to solve this problem: I have several user roles in my system, and for many of my controller actions, I need to deal with slightly different data. For example, take /Users/Edit/1 This allows a Moderator to edit a users email address, but Administrators to edit a user's email address and password. I'd like a design for separating the two different bits of action code for the GET and the POST. Solutions I've come up with so far are: Switch inside each method, however this doesn't really help when i want different model arguments on the POST :( Custom controller factory which chooses a UsersController_ForModerators and UsersController_ForAdmins instead of just UsersController from the controller name and current user role Custom action invoker which choose the Edit_ForModerators method in a similar way to above Have an IUsersController and register a different implementation of it in my IoC container as a named instance based on Role Build an implementation of the controller at runtime using Castle DynamicProxy and manipulate the methods to those from role-based implementations Im preferring the named IoC instance route atm as it means all my urls/routing will work seamlessly. Ideas? Suggestions?

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• System.ServiceModel.CommunicationException on overloading webservice

  - by soldieraman

  I am load testing my webservice and get a System.ServiceModel.CommunicationException when I use 10 threads to communicate to it (without any sleep in between) - basically testing 10 conenctions at a time - through a windows application An error occurred while receiving the HTTP response to http://localhost/XXX/XXXService.asmx. This could be due to the service endpoint binding not using the HTTP protocol. This could also be due to an HTTP request context being aborted by the server (possibly due to the service shutting down). See server logs for more details. Why would this happen and how to best resolve it

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• Why does Excel expose an 'Evaluate' method at all?

  - by jtolle

  A few questions have come up recently involving the Application.Evaluate method callable from Excel VBA. The old XLM macro language also exposes an EVALUATE() function. Both can be quite useful. Does anyone know why the general expression evaluator is exposed, though? My own hunch is that Excel needed to give people a way to get ranges from string addresses, and to get the value of named formulas, and just opening a portal to the expression evaluator was the easiest way. But of course you don't need the ability to evaluate arbitrary expressions just to do that. Application.Evaluate seems kind of...unfinished. It isn't very well documented, and there are quite a few quirks and limitations (as described by Charles Williams here: http://www.decisionmodels.com/calcsecretsh.htm) with what is exposed. I suppose the answer could be simply "why not expose it?", but I'd be interested to know what design decisions led to this feature. Failing that, I'd be interested to hear other hunches.

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• How can I share Configuration Settings across multiple projects in Visual Studio?

  - by Muneeb

  Ok I know this may be a design issue, so I would love to have remarks on that as well. I have a Visual Studio web application solution. I have three projects as UserInterface, BusinessLogic and DataAccess. I had to store some user defined settings and I created configSections in the config file. I access these configSections through classes which inherit from .NET's ConfigurationSection base class. So in short for every project I had a separate configSection and for that corresponding configSection I had a class in that project inheriting from ConfigurationSection to access the config section settings. This works all sweet. But the problem arises if there is any setting which I need to use across multiple projects. So If I need to use a setting defined in UserInterface project configSection in, let say, BusinessLogic project I have to actually make a copy of that setting in the BusinessLogic's configSection. This ends up having the same setting copied across multiple configSections. Isn't this a bit too redundant?

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• django blog - post- reply system display replies

  - by dana

  I have a mini blog app, and a reply system. I want to list all mini blog entries, and their replies, if there are any. i have in views.py def profile_view(request, id): u = UserProfile.objects.get(pk=id) paginator = New.objects.filter(created_by = request.user) replies = Reply.objects.filter(reply_to = paginator) return render_to_response('profile/publicProfile.html', { 'object_list': u, 'list':paginator, 'replies':replies }, context_instance=RequestContext(request)) and in the template: <h3>Recent Entries:</h3> {% for object in list %} <li>{{ object.post }} <br /> {% for object in replies %} {{ object.reply }} <br /> {% endfor %} mention : reply_to is a ForeignKey to New, and New is the name of the 'mini blog' table But it only shows all the replies for each blog entry, not the reply for every entry, if there is one thanks

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• django templating system inheritance issue

  - by Suhail

  hi, i am having issues with my django templating system, i have a base.html file, which contains the content which will be common on all the web pages of the web site, the base.html file fetches some dynamic content, like the categories and the archives, which are passed to it by a python file, which fetches the categories and the archives data from a mysql database. the issue when i inherit this base.html file in other html files like index.html: {% extends "base.html" %} and when when i call the main index URL for ex: http://mywebsite.com/index/ the index page gets loaded, but the categories and the archives data that should get loaded from the base.html file does not. what am i doing wrong, please help.

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• Resources to learn about engineering aspects of data analytics (OLAP, warehousing, ETL, etc.)

  - by JT

  I'm a math/stats guy, interested in learning more about the engineering aspects of "data analytics" (this may be an overly broad term, this is a case of "I don't know what I don't know", so I'm not sure how to be more specific). I'm fine with manipulating and analyzing the data once it's already stored somewhere and I can access it, and I'm fine with writing scripts and SQL queries (and have a general knowledge of things like normalization). What I don't know is the whole engineering process of capturing and storing the data. For example, terms I've heard thrown about that I only vaguely understand the meaning of include: - OLAP, OLTP - Data warehousing - ETL - ??? What's a good book (or any other resource) to learn about these kinds of things? What are things I should know about database design (normalization seems kinda "obvious" to me, something I would have done even before I knew the term -- is there anything else?)? In other words, for jobs falling under the umbrella term of "analytics engineer", what kinds of things should I know?

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• System.XML or Regex.Replace?

  - by cam

  I'm generating a large amount of XML documents from a set of values in an Excel file. The only thing that changes for each XML document is the values. I figured the best way to generate these documents was to make a "XML skeleton" (since the XML format never changes) and then plug in symbols like "&%blahNameblahTest", so then I could just preform a Regex.Replace on each value. I will be handing over this project to another developer and I'm wondering if I should convert the project to generate the XML file manually everytime through the System.XML namespace. The only advantages I see to this is ensuring that the XML document is valid. The current method would be more readable than that method, and way faster since I'm generating around 1500 documents.

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• What is the difference between MVC model 1 and model 2?

  - by Alex Ciminian

  I've recently discovered that MVC is supposed to have two different flavors, model one and model two. I'm supposed to give a presentation on MVC1 and I was instructed that "it's not the web based version, that is refered to as MVC2". As the presentations are about design patterns in general, I doubt that this separation is related to Java (I found some info on Sun's site, but it seemed far off) or ASP. I have a pretty good understanding of what MVC is and I've used several (web) frameworks that enforce it, but this terminology is new to me. How is the web-based version different from other MVC (I'm guessing GUI) implementations? Does it have something to do with the stateless nature of HTTP? Thanks, Alex

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• Which tool / technology: System management for databases and dependent services

  - by Filburt

  A follow-up on this system management question: Since I probably will not get much feedback on serverfault I'll give it a try here. My main concern is to reflect the dependencies between the databases, services ans tasks/jobs I'll have to manage. Besides considering Powershell, I even thought about using MSBuild because it would allow for modeling dependencies and reuse configuration targets. In other words: What technology should I use to develop a flexible solution that will allow me to stop service A, B and C on machine D in the right order and disable task E on machine F when taking down database X?

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• Algorithm for Source Control System?

  - by Michael Stum

  I need to write a simple source control system and wonder what algorithm I would use for file differences? I don't want to look into existing source code due to license concerns. I need to have it licensed under MPL so I can't look at any of the existing systems like CVS or Mercurial as they are all GPL licensed. Just to give some background, I just need some really simple functions - binary files in a folder. no subfolders and every file behaves like it's own repository. No Metadata except for some permissions. Overall really simple stuff, my single concern really is how to store only the differences of a file from revision to revision without wasting too much space but also without being too inefficient (Maybe store a full version every X changes, a bit like Keyframes in Videos?)

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• How can I find file system concurrency issues ?

  - by krosenvold

  I have an application running on Linux, and I find myself wanting windows (!). The problem is that every 1000 times or so I run into concurrency problems that are consistent with concurrent reading/writing of files. I am fairly sure that this behavior would be prohibited by file locking under Windows, but I don't have any sufficiently fast windows box to check. There is simply too much file access (too much data) to expect strace to work reliably - the sheer volume of output is likely to change the problem too. It also happens on different files every time. Ideally I would like to change/reconfigure the linux file system to be more restrictive (as in fail-fast) wrt concurrent access. Are there any tools/settings I can use to achieve this ?

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