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• Inline Form Validation in Django

  - by allanhenderson

  Newbie request that seems difficult to implement. I would like to make an entire inline formset within an admin change form compulsory.. so in my current scenario when I hit save on an Invoice form (in Admin) the inline Order form is blank. I'd like to stop people creating invoices with no orders associated. Anyone know an easy way to do that? Normal validation like (required=True) on the model field doesn't appear to work in this instance. Thanks!!

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• Delphi component or library to display mathematical expressions

  - by Svein Bringsli

  I'm looking for a simple component that displays mathematical expressions in Delphi. When I started out I thought it would be easy to find something on the net, but it turns out it was harder than anticipated. There are lots and lots of components that will parse mathematical expressions, but few (none?) that will display them. Ideally I would like a component as simple as a TLabel, where I could set the caption to some expression and it would be displayed correctly, but some sort of library that let's me draw expressions to a canvas would also be sufficient for my needs. Update: I'm not talking about plotting graphs of functions or something like that. I want to display (for instance) (X^2+3)/X like this:

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• Why can't I reclaim my dynamically allocated memory using the "delete" keyword?

  - by synaptik

  I have the following class: class Patient { public: Patient(int x); ~Patient(); private: int* RP; }; Patient::Patient(int x) { RP = new int [x]; } Patient::~Patient() { delete [] RP; } I create an instance of this class on the stack as follows: void f() { Patient p(10); } Now, when f() returns, I get a "double free or corruption" error, which signals to me that something is attempted to be deleted more than once. But I don't understand why that would be so. The space for the array is created on the heap, and just because the function from inside which the space was allocated returns, I wouldn't expect the space to be reclaimed. I thought that if I allocate space on the heap (using the new keyword), then the only way to reclaim that space is to use the delete keyword. Help! :)

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• Is there a limit on the number of mutex objects that can be created in a Windows process?

  - by young-phillip

  I'm writing a c# application that can create a series of request messages. Each message could have a response, that needs to be waited on by a consumer. Where the number of outstanding request messages is constrained, I have used the windows EVENT to solve this problem. However, I know there is a limit on how many EVENT objects can be created in a single process, and in this instance, its possible I might exceed that limit. Does anyone know if there is a similar limit on creation of mutex objects or semaphores? I know this can be solved by some sort of pool of shared resources, that are grabbed by consumers when they need to wait, but it would be more convenient if each request message could have its own sync object.

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• Use of (non) qualified names

  - by AProgrammer

  If I want to use the name baz defined in package foo|bar|quz, I've several choices: provide fbq as a short name for foo|bar|quz and use fbq|baz use foo|bar|quz|baz import baz from foo|bar|quz|baz and then use baz (or an alias given in the import process) import all public symbols from foo|bar|quz|baz and then use baz For the languages I know, my perception is that the best practice is to use the first two ways (I'll use one or the other depending on the specific package full name and the number of symbols I need from it). I'd use the third only in a language which doesn't provide the first and hunt for supporting tools to write the import statements. And in my opinion the fourth should be reserved to package designed with than import in mind, for instance if all exported symbols start with a prefix or contains the name of the package. My questions: what is in your opinion the best practice for your favorite languages? what would you suggest in a new language? what would you suggest in an old language adding such a feature?

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• What project management methodology to use to develop new software internally?

  - by Setareh

  As part of my assignment I have to answer this question: The Sales Department has decided to develop new software internally. They will thus need to manage the IT project formally. Briefly describe two suitable project management methodologies models that could be used. I'm quite confused by the amount of methodologies. I Thought maybe PMBOK and SCRUM might be the best but still not sure if they are the ones for developing software internally. or whether they work for small projects, for instance. The thing about PRINCE2 is that is very comprehensive and seems to suit the large projects, however I read that it also suits to small projects as well. Any suggestions, which project management methodologies models to use for developing new software internally? What would be two suitable project management methodologies models?

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• Singleton Properties

  - by coffeeaddict

  Ok, if I create a singleton class and expose the singleton object through a public static property...I understand that. But my singleton class has other properties in it. Should those be static? Should those also be private? I just want to be able to access all properties of my singleton class by doing this: MySingletonClass.SingletonProperty.SomeProperty2 Where SingletonProperty returns me the single singleton instance. I guess my question is, how do you expose the other properties in the singleton class..make them private and then access them through your public singleton static property?

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• Memory leak with WPF & ItemsControl (VB.NET)

  - by Matt H.

  I have an ItemsControl that uses a DataTemplate to display properties in my customClass that implements INotifyPropertyChanged... Pretty straightforward... Some items in the DataTemplate use CommandBindings (such as buttons), and a few have some code-behind (yuck). When I empty the ItemsControl and set all instances of customClass = Nothing , no memory is released from my program. This becomes a problem pretty quickly! Any idea where I should start looking? I've even gone so far as to completely traverse the visual tree of each DataTemplate instance and set each Visual = Nothing. I'm not really if that's supposed to have any effect though.

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• Ruby: change each value in a hash with something like #collect for arrays?

  - by Adam Nonymous

  Hi! I'd like to replace each value in a hash with value.some_method. For example in a simple hash {"a" = "b", "c" = "d"} every value should be .upcase-d so it looks like {"a" = "B", "c" = "D"}. I tried #collect and #map but always just get arrays back. Is there an 'elegant' way to do this? Thanks in advance, Adam Nonymous UPDATE: Damn, I forgot: The hash is in an instance variable which should not be changed. I need a new hash with the changed values, but would prefer not to define that variable explicitly and then loop over the hash filling it. Something like new_hash = hash.magic {...} ;)

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• How to build boost foreach cycle

  - by Ockonal

  Hi guys! I have some abstract class called IClass (has pure virtual function). There are some classes which inherit IClass: CFirst, CSecond. I want to add objects of classes which inherit into boost::ptr_vector: class IClass { virtual void someFunc() = 0; }; class CFirst : public IClass { }; class CSecond : public IClass { }; boost::ptr_vector<IClass> objectsList; objectsList.push_back(new CFirst()); objectsList.push_back(new CSecond()); And now my goal is to call function (which is declarated in IClass) from all objects in objectsList. I'd prefer to use BOOST_FOREACH: foreach(IClass tempObj, objectsList) { tempObj.someFunc(); } The problem is that IClass - abstract class, so I can't make instance of it for the foreach-cycle. What should I do?

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• Using svn with xampp for php projects

  - by idrish

  I have heard a lot about version control and would like to work on it. I read some tutorials about the same. However i am not quite sure how svn works with xampp. I have installed svn, Tortoise svn and made the necessary changes in xampp. For instance i copied the two required modules to c:/xampp/apache/modules and also made changes to the conf file in apache. Here are the changes made in c:/xampp/apache/conf/httpd.conf. # Configure Subversion repository <Location /svn> DAV svn SVNPath “C:\svn” AuthType Basic AuthName “Subversion repository” AuthUserFile “c:\svn_conf\passwd” Require valid-user </Location>t I created the repository at c:/svn and also created the password file. However when i visit http:/localhost/svn i get a 404 page not found error. Where am i going wrong. what am i missing.? Any pointers?? Thanks in advance.

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• How to preserve whitespace indentation of text enclosed in HTML <pre> tags excluding the current indentation level of the <pre> tag in the document?

  - by Michael Barton

  I'm trying to display my code on a website but I'm having problems preserving the whitespace indentation correctly. For instance given the following snippet: <html> <body> Here is my code: <pre> def some_funtion return 'Hello, World!' end </pre> <body> </html> This is displayed in the browser as: Here is my code: def some_funtion return 'Hello, World!' end When I would like it displayed as: Here is my code: def some_funtion return 'Hello, World!' end The difference is that that current indentation level of the HTML pre tag is being added to the indentation of the code. I'm using nanoc as a static website generator and I'm using google prettify to also add syntax highlighting. Can anyone offer any suggestions?

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• Fill object data from several tables using hibernate mapping

  - by Udo Fholl

  Hi all, I'd like to know if it is possible to fill up a class data from database using the hibernate hbm (mapping). For instance: public class someClass { List<OtherClass> otherClasses; List<YetAnotherClass> yetAnotherClasses; //Constructors ? class OtherClass { String name; //setters, getters } class YetAnotherClass { String name; //setters, getters } //setters, getters } Using an hbm can I fill in the data from tables OTHER_CLASS_TABLE and YET_ANOTHER_CLASS_TABLE? I have no such SOME_CLASS_TABLE since this info is for viewing only. I've been playing with the <join table=""><subselect> and different constructors... But it is not working Thanks! Sorry for my english!

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• Can a DataTemplate be a Page?

  - by dthrasher

  I'm using the MVVM pattern to create a WPF standalone application. My program compiles in Visual Studio 2008, but I frequently get warnings in the editor for my DataTemplates. In my MainWindow.xaml, I've defined the following DataTemplate: <DataTemplate DataType="{x:Type ViewModels:TagViewModel}"> <Views:TagView /> </DataTemplate> Where "TagView" is derived from a Page, rather than an ordinary UserControl. This causes the following message to appear every time I reload the designer in Visual Studio: "Could not create an instance of type 'TagView'. Yet the solution compiles fine and the program seems to work properly. Is this a bug in the Visual Studio 2008 editor? Or am I doing something wrong?

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• Factory Method pattern and public constructor

  - by H4mm3rHead

  Hi, Im making a factory method that returns new instances of my objects. I would like to prevent anyone using my code from using a public constructor on my objects. Is there any way of doing this? How is this typically accomplished: public abstract class CarFactory { public abstract ICar CreateSUV(); } public class MercedesFactory : CarFactory { public override ICar CreateSUV() { return new Mercedes4WD(); } } I then would like to limit/prevent the other developers (including me in a few months) from making an instance of Mercedes4WD. But make them call my factory method. How to?

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• Searching for patterns to create a TCP Connection Pool for high performance messaging

  - by JoeGeeky

  I'm creating a new Client / Server application in C# and expect to have a fairly high rate of connections. That made me think of database connection pools which help mitigate the expense of creating and disposing connections between the client and database. I would like to create a similar capability for my application and haven't been able to find any good examples of how to apply this pattern. Do I really need to spin up an instance of a TcpClient every time I want to send a message to the server and receive a receipt message? Each connection is expected to transport between 1-5KB with each receiving a 1KB response message. I realize this question is somewhat vague, but I am starting from scratch so I am open to suggestions. Even if that means my suppositions are all wrong.

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• dynamic behavior of factory class

  - by manu1001

  I have a factory class that serves out a bunch of properties. Now, the properties might come either from a database or from a properties file. This is what I've come up with. public class Factory { private static final INSTANCE = new Factory(source); private Factory(DbSource source) { // read from db, save properties } private Factory(FileSource source) { // read from file, save properties } // getInstance() and getProperties() here } What's a clean way of switching between these behaviors based on the environment. I want to avoid having to recompile the class each time.

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• Is it possible to modify ASP.NET to no longer require runat="server"?

  - by sean2078

  I know why runat="server" is currently required (ASP.NET why runat="server"), but the consensus is that it should not be required if you incorporate a simple default into the design (I agree of course). Would it be possible to modify, extend, decompile and recreate, intercept or otherwise change the behavior of how ASP.NET parses ASPX and ASCX files so that runat="server" would no longer be required? For instance, I assume that a version of Mono could be branched to accomplish this goal. In case specific requirements are helpful, the following highlights one design: During parsing, when configured namespace tags are encountered (such as "asp"), default the element's runat property to "server" During parsing, when configured namespace tags are encountered (such as "asp"), if the element's runat property value is available, then that value should be used in place of the default New page-level setting introduced (can be set in the page directive or web.config) that specifies the default runat value for a specific namespace tag

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• BackgroundWorker RunWorkerCompleted in a Component

  - by Sphynx

  I'm familiar with the following: "If the operation raises an exception that your code does not handle, the BackgroundWorker catches the exception and passes it into the RunWorkerCompleted event handler, where it is exposed as the Error property of System.ComponentModel.RunWorkerCompletedEventArgs. If you are running under the Visual Studio debugger, the debugger will break at the point in the DoWork event handler where the unhandled exception was raised." However, I've encountered a weird glitch. In my component, there's an instance of BackgroundWorker. Even though it's not running in the debugger, the exception remains unhandled by the worker. Even simplified code produces an unhandled exception (and RunWorkerCompleted doesn't fire): Throw New ArgumentException("Test") The main thing is the code of RunWorkerComplete: RaiseEvent UpdateComplete(Me, New AsyncCompletedEventArgs(e.Error, e.Cancelled, e.Result)) I need the component to expose the worker exception through a public event. If I remove the RaiseEvent call, the exception becomes handled by the worker, and accessible through e.Error. Apparently, raising an event causes the worker to miss the exception. How can that be?

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• Make xargs execute the command once for each line of input

  - by Readonly

  How can I make xargs execute the command exactly once for each line of input given? It's default behavior is to chunk the lines and execute the command once, passing multiple lines to each instance. From http://en.wikipedia.org/wiki/Xargs: find /path -type f -print0 | xargs -0 rm In this example, find feeds the input of xargs with a long list of file names. xargs then splits this list into sublists and calls rm once for every sublist. This is more efficient than this functionally equivalent version: find /path -type f -exec rm '{}' \; I know that find has the "exec" flag. I am just quoting an illustrative example from another resource.

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• Multiblog engine for asp.net

  - by Andrey

  I know, different forms of this questions were asked on this site multiple times, but I haven't seen a single answer that would satisfy my need. I need a ASP.NET based blogging engine that wouul use SQL Server as a back end and allow multiple independet blogs in one app instance. I'm writing a community website for major bank and blogging is the piece I'm not sure about. Answers to other questions include a broad spectrum from BlogEngine.NET (doesn't support multiple blogs) to CommunityServer (a beast! blogging is just asmall piece of it). I don't want to install a full-blown CRM and just use blogging, I want a blogging engine. I don't mind to buy a commercial one but I can't find one. I'm pretty much stuck, and any ideas are highly appreciated!

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• C# Getting Just Date From Timestamp

  - by Soo

  If I have a timestamp in the form: yyyy-mm-dd hh:mm:ss:mmm How can I just extract the date from the timestamp? For instance, if a timestamp reads: "2010-05-18 08:36:52:236" what is the best way to just get 2010-05-18 from it. What I'm trying to do is isolate the date portion of the timestamp, define a custom time for it to create a new time stamp. Is there a more efficient way to define the time of the timestamp without first taking out the date, and then adding a new time?

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• Setting up a SQL server outside the domain

  - by Ben

  Hi, im very new to this. I've set up an account "SQLBOX" thats on the a network, but not connected to the domain. I have installed an instance of SQL Server 2008 and am trying to connect to it from another machine on the network but am getting "Cannot connect to "SQLBOX"". From the "SQLBOX" i can connect to sqlservers on the domain, but not vice-versa. Any help would be greatly appreciated. Sorry if the description isn't great. EDIT I can ping the box from a machine on the domain

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• What's the easiest way to use OAuth with ActiveResource?

  - by Barry Hess

  I'm working with some old code and using ActiveResource for a very basic Twitter integration. I'd like to touch the app code as little as possible and just bring OAuth in while still using ActiveResource. Unfortunately I'm finding no easy way to do this. I did run into the oauth-active-resource gem, but it's not exactly documented and it appears to be designed for creating full-on API wrapper libraries. As you can imagine, I'd like to avoid creating a whole Twitter ActiveResource API wrapper for this one legacy change. Any success stories out there? In my instance, it might be quicker to just leave ActiveResource rather than get this working. I'm happy to be proven wrong!

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• How can I pass a javaScript function to a Java Method to act as a callback (Rhino)

  - by Dan Howard

  Hi everyone, Basically I'm trying to pass a javaScript function to a Java method to act as a callback to the script. I can do it - sort of - but the object I receive is a sun.org.mozilla.javascript.internal.InterpretedFunction and I don't see a way to invoke it. Any ideas? Here's what I have so far: var someNumber = 0; function start() { // log is just an log4j instance added to the Bindings log.info("started...."); someNumber = 20; // Test is a unit test object with this method on it (taking Object as a param). test.callFromRhino(junk); } function junk() { log.info("called back " + someNumber); }

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