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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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• Shouldn't ObjectInputStream extend FilterInputStream?

  - by Vaibhav Bajpai

  The block quotes are from the Java Docs - A FilterInputStream contains some other input stream, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality. A DataInputStream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. The DataInputStream therefore extends FilterInputStream An ObjectInputStream deserializes primitive data and objects previously written using an ObjectOutputStream. However, for some reason the ObjectInputStream does NOT extend FilterInputStream even though it is also reading objects (this time and not primitive types) from the underlying input stream. Here is the branching of the concerned classes. Is there is a design reasoning for the same?

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• Fully customized login system in Django?

  - by user367817

  Hey, I am currently writing an application which I plan to sell as SaaS. Without giving away "secrets," I can say that it is basically a "document editing system" in which many users will be submitting documents. The basic heirarchy is this: Institution Individual Document Sub-document So each Individual should be able to BROWSE all documents that were submitted by anybody in their institution, but should only be able to EDIT documents that they created. No individual should even be aware of the existence of another Institution--that should all be completely hidden. I have written a Django/Python class that would facilitate this, but every document regarding authentication that I have read requires that I use the User object. Is this just a limitation of Django, or is there a way to do this? If there is a way, how can I get my own "Individual" class details attached to the "request" objects so I can validate the things I should be showing the users?

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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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• 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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• 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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• 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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• Where and how to validate and map ViewModel?

  - by chobo

  Hi, I am trying to learn Domain Driven Design and recently read that lots of people advocate creating a ViewModels for your views that store all the values you want to display in a given view. My question is how should I do the form validation? should I create separate validation classes for each view, or group them together? I'm also confused on what this would look like in code. This is how I currently think validation and viewmodels fit in to the scheme of things: View (some user input) - Controller - FormValidation(of ViewModel) - (If valid map to ViewModel to Domain Model) - Domain Layer Service - Infrastructure Thanks! P.S. I use Asp.net MVC with C#

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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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• 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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• 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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• 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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• 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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• 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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• 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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• 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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• 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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• 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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• MongoDB RSS Feed Entries, Embed the Entries in the Feed Object?

  - by Patrick Klingemann

  I am saving a reference to an RSS Feed in MongoDB, each Feed has an ever growing list of Entries. As I'm designing my schema, I'm concerned about this statement from the MongoDB Schema Design - Embed vs. Reference Documentation: If the amount of data to embed is huge (many megabytes), you may read the limit on size of a single object. This will surely happen if I understand the statement correctly. So the question is, I am correct to assume that I should not embed the Feed Entries within a Feed because I'll eventually reach the limit on size of a single object?

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• Cannot implicitly convert type System.Collection.Generic.IEnumberable

  - by Cen

  I'm receiving this error in my Linq statement --- Cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'hcgames.ObjectClasses.ShoppingCart.ShoppingCartCartAddon'. An explicit conversion exists (are you missing a cast?) From this query ShoppingCartItems items = Cart.GetAllItems(); ShoppingCartCartAddons addons = Cart.GetAllAddons(); var stuff = from x in items select new ShoppingCartItem() { ProductID = x.ProductID, Quantity = x.Quantity, Name = x.Name, Price = x.Price, Weight = x.Weight, Addons = (from y in addons where y.ShoppingCartItemID == x.ID select y) }; I can not figure out how to cast this properly. Any suggestions? Thanks for your 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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• 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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• System::IDisposable woes

  - by shadeMe

  public ref class ScriptEditor : public Form { public: typedef map<UInt32, ScriptEditor^> AlMap; static AlMap AllocationMap; Form^ EditorForm; RichTextBox^ EditorBox; StatusBar^ EditorStatusBar; StatusBarPanel^ StatusBarLineNo; void Destroy() { EditorForm->Close(); } ScriptEditor(unsigned int PosX, unsigned int PosY); }; The above code throws an Error C2039: '{dtor}' : is not a member of 'System::IDisposable'. I'm quite lost after having looked into articles that explain how the CLR manages memory. Any advice on getting rid of it would be appreciated. My first dabble in C+++/CLI isn't going too well.

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• How to create skype like message window?

  - by Miraaj

  Hi all, I am just trying to design skype like message window , for this I have taken the NSDrawer element. It contains : a table view on left, menu items on top, text field on right bottom and text view at central portion on right side. Using text view I can play with string being displayed but I cannot draw the line between messages or round rectangle surrounding user name and time stamp. Can anyone suggest me how can I achieve same look and feel for central message view as in skype?? or is there any better control then NSTextView to be used for it?? Thanks, for any suggestion... Miraaj

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