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  • A Django form for entering a 0 to n email addresses

    - by Erik
    I have a Django application with some fairly common models in it: UserProfile and Organization. A UserProfile or an Organization can both have 0 to n emails, so I have an Email model that has a GenericForeignKey. UserProfile and Organization Models both have a GenericRelation called emails that points back to the Email model (summary code provided below). The question: what is the best way to provide an Organization form that allows a user to enter organization details including 0 to n email addresses? My Organization create view is a Django class-based view. I'm leading towards creating a dynamic form and an enabling it with Javascript to allow the user to add as many email addresses as necessary. I will render the form with django-crispy-forms. I've thought about doing this with a formset embedded within the form, but this seems like overkill for email addresses. Embedding a formset in a form delivered by a class-based view is cumbersome too. Note that the same issue occurs with the Organization fields phone_numbers and locations. emails.py: from django.db import models from parent_mixins import Parent_Mixin class Email(Parent_Mixin,models.Model): email_type = models.CharField(blank=True,max_length=100,null=True,default=None,verbose_name='Email Type') email = models.EmailField() class Meta: app_label = 'core' organizations.py: from emails import Email from locations import Location from phone_numbers import Phone_Number from django.contrib.contenttypes import generic from django.db import models class Organization(models.Model): active = models.BooleanField() duns_number = models.CharField(blank=True,default=None,null=True,max_length=9) # need to validate this emails = generic.GenericRelation(Email,content_type_field='parent_type',object_id_field='parent_id') legal_name = models.CharField(blank=True,default=None,null=True,max_length=200) locations = generic.GenericRelation(Location,content_type_field='parent_type',object_id_field='parent_id') name = models.CharField(blank=True,default=None,null=True,max_length=200) organization_group = models.CharField(blank=True,default=None,null=True,max_length=200) organization_type = models.CharField(blank=True,default=None,null=True,max_length=200) phone_numbers = generic.GenericRelation(Phone_Number,content_type_field='parent_type',object_id_field='parent_id') taxpayer_id_number = models.CharField(blank=True,default=None,null=True,max_length=9) # need to validate this class Meta: app_label = 'core' parent_mixins.py from django.contrib.contenttypes.models import ContentType from django.contrib.contenttypes import generic from django.db import models class Parent_Mixin(models.Model): parent_type = models.ForeignKey(ContentType,blank=True,null=True) parent_id = models.PositiveIntegerField(blank=True,null=True) parent = generic.GenericForeignKey('parent_type', 'parent_id') class Meta: abstract = True app_label = 'core'

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  • Database migration pattern for Java?

    - by Eno
    Im working on some database migration code in Java. Im also using a factory pattern so I can use different kinds of databases. And each kind of database im using implements a common interface. What I would like to do is have a migration check that is internal to the class and runs some database schema update code automatically. The actual update is pretty straight forward (I check schema version in a table and compare against a constant in my app to decide whether to migrate or not and between which versions of schema). To make this automatic I was thinking the test should live inside (or be called from) the constructor. OK, fair enough, that's simple enough. My problem is that I dont want the test to run every single time I instantiate a database object (it runs a query so having it run on every construction is not efficient). So maybe this should be a class static method? I guess my question is, what is a good design pattern for this type of problem? There ought to be a clean way to ensure the migration test runs only once OR is super-efficient.

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  • How should I setup my Visual Studio projects/solutions in a Mercurial repository?

    - by Dave A
    At my company we have a few different web apps that each share some common libraries. The Visual Studio setup looks like this. Website 1 Solution Website 1 Shared Library 1 Project Shared Library 2 Project Website 2 Solution Website 2 Shared Library 1 Project Shared Library 2 Project Windows Service Solution Windows Service Project Shared Library 1 Project Shared Library 2 Project Shared Library Solution Shared Library 1 Project Shared Library 2 Project All Projects Solution Website 1 Website 2 Windows Service Project Shared Library 1 Project Shared Library 2 Project We want to start using Mercurial for source control, but I'm still not sure the best way to do it. From what I've read you're supposed to use a separate repository for each project. No problem there, but where do the Visual Studio solution files (.sln) go? Should there be a separate repository with just an .sln file? Ideally the projects that use the shared libraries should all use the same version, and the solution "All Projects Solution" should build without errors, but sometimes we need to branch the shared libraries. What is the best way to do this, and how would the repositories be setup? How do I get a working copy of a certain branch/tag of the Website 1 solution when every project is in a separate repository. Do I have to pull each one separately, or write a script to do it all at once? Can tortoise hg do that for me? Any other tips to make this process easier?

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  • Class/Model Level Validation (as opposed to Property Level)? (ASP.NET MVC 2.0)

    - by Erx_VB.NExT.Coder
    Basically, what the title says. I have several properties that combine together to really make one logical answer, and i would like to run a server-side validation code (that i write) which take these multiple fields into account and hook up to only one validation output/error message that users see on the webpage. I looked at scott guthries method of extending an attribute and using it in yoru dataannotations declarations, but, as i can see, there is no way to declare a dataannotations-style attribute on multiple properties, and you can only place the declarations (such as [Email], [Range], [Required]) over one property :(. i have looked at the PropertiesMustMatchAttribute in the default mvc 2.0 project that appears when you start a new project, this example is as useful as using a pair of pins to check your motor oil - useless! i have tried this method, however, creating a class level attribute, and have no idea how to display the error from this in my aspx page. i have tried html.ValidationMessage("ClassNameWhereAttributeIsAdded") and a variety of other thing, and it has not worked. and i should mention, there is NOT ONE blog post on doing validation at this level - despite this being a common need in any project or business logic scenario! can anyone help me in having my message displayed in my aspx page, and also if possible a proper document or reference explaining validation at this level?

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  • dlopen / dlsym with as little linking as possible

    - by johannes
    I have an application which can make use of plugins which are loaded at runtime using dlopen. Each of the plugins defines a function toretrieve the plugin information which is defined using a common structure. Something like that: struct plugin { char *name; char *app_version; int app_verion_id; char *plugin_version; int plugin_version_id; /* ... */ }; struct plugin p = { "sample plugin",APP_VERION,APP_VERSION_ID,"1.2.3",10203 }; struct plugin *get_plugin() { return &p; } This works well and plugins can be loaded. Now i want to build a small tool to read these properties without linking the whole application. For doing that I have some code like this: void *handle; struct plugin *plugin; struct plugin *(get_plugin*)(); handle = dlopen(filename, RTLD_LAZY); if (!handle) { /*...return; ...*/ } get_plugin = dlym(handle, "get_plugin"); if (!get_plugin) { /*...return; ...*/ } plugin = get_plugin(); printf("Plugin: %s\n", plugin->name); This works nice for simple plugins. The issue is that many plugins reference further symbols from the application, which are resolved even though RTLD_LAZY was set. (like global variables from the application which are used to initialize plugin-global things) So the dlopen() call fails with an error like fatal: relocation error: file sample_plugin.so: symbol application_some_symbol: referenced symbol not found. As I just want to have access to the single simple structure I was wondering how I can prevent the linker from doing that much of his work.

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  • Abusing the word "library"

    - by William Pursell
    I see a lot of questions, both here on SO and elsewhere, about "maintaining common libraries in a VCS". That is, projects foo and bar both depend on libbaz, and the questioner is wondering how they should import the source for libbaz into the VCS for each project. My question is: WTF? If libbaz is a library, then foo doesn't need its source code at all. There are some libraries that are reasonably designed to be used in this manner (eg gnulib), but for the most part foo and bar ought to just link against the library. I guess my thinking is: if you cut-and-paste source for a library into your own source tree, then you obviously don't care about future updates to the library. If you care about updates, then just link against the library and trust the library maintainers to maintain a stable API. If you don't trust the API to remain stable, then you can't blindly update your own copy of the source anyway, so what is gained? To summarize the question: why would anyone want to maintain a copy of a library in the source code for a project rather than just linking against that library and requiring it as a dependency? If the only answer is "don't want the dependency", then why not just distribute a copy of the library along with your app, but keep them totally separate?

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  • JVM/CLR Source-compatible Language Options

    - by Nathan Voxland
    I have an open source Java database migration tool (http://www.liquibase.org) which I am considering porting to .Net. The majority of the tool (at least from a complexity side) is around logic like "if you are adding a primary key and the database is Oracle use this SQL. If database is MySQL use this SQL. If the primary key is named and the database is Postgres use this SQL". I could fork the Java codebase and covert it (manually and/or automatically), but as updates and bug fixes to the above logic come in I do not want to have to apply it to both versions. What I would like to do is move all that logic into a form that can be compiled and used by both Java and .Net versions naively. The code I am looking to convert does not contain any advanced library usage (JDBC, System.out, etc) that would vary significantly from Java to .Net, so I don't think that will be an issue (at worst it can be designed around). So what I am looking for is: A language in which I can code common parts of my app in and compile it into classes usable by the "standard" languages on the target platform Does not add any runtime requirements to the system Nothing so strange that it scares away potential contributors I know Python and Ruby both have implementations on for the JVM and CLR. How well do they fit my requirements? Has anyone been successful (or unsuccesful) using this technique for cross-platform applications? Are there any gotcha's I need to worry about?

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  • CQRS - The query side

    - by mattcodes
    A lot of the blogsphere articles related to CQRS (command query repsonsibility) seperation seem to imply that all screens/viewmodels are flat. e.g. Name, Age, Location Of Birth etc.. and thus the suggestion that implementation wise we stick them into fast read source etc.. single table per view mySQL etc.. and pull them out with something like primitive SqlDataReader, kick that nasty nhibernate ORM etc.. However, whilst I agree that domain models dont mapped well to most screens, many of the screens that I work with are more dimensional, and Im sure this is pretty common in LOB apps. So my question is how are people handling screen where by for example it displays a summary of customer details and then a list of their orders with a [more detail] link etc.... I thought about keeping with the straight forward SQL query to the Query Database breaking off the outer join so can build a suitable ViewModel to View but it seems like overkill? Alternatively (this is starting to feel yuck) in CustomerSummaryView table have a text/big (whatever the type is in your DB) column called Orders, and the columns for the Order summary screen grid are seperated by , and rows by |. Even with XML datatype it still feeel dirty. Any thoughts on an optimal practice?

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  • Programming tips for writing document editors?

    - by Tesserex
    I'm asking this because I'm in the process of writing two such editors for my Mega Man engine, one a tileset editor, and another a level editor. When I say document editor, I mean the superset application type for things like image editors and text editors. All of these share things like toolbars, menu options, and in the case of image editors, and my apps, tool panes. We all know there's tons of advice out there for interface design in these apps, but I'm wondering about programming advice. Specifically, I'm doubting my code designs with the following things: Many menu options toggle various behaviors. What's the proper way to reliably tie the checked state of the option with the status of the behavior? Sometimes it's more complicated, like options being disabled when there's no document loaded. More and more consensus seems to be against using MDI, but how should I control tool panes? For example, I can't figure out how to get the panels to minimize and maximize along with the main window, like Photoshop does. When tool panels are responsible for a particular part of the document, who actually owns that thing? The main window, or the panel class? How do you do communication between the tool panels and the main window? Currently mine is all event based but it seems like there could be a better way. This seems to be a common class of gui application, but I've never seen specific pointers on code design for them. Could you please offer whatever advice or experience you have for writing them?

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  • Help me with DB design

    - by eugeneK
    Hi, i'm developing text ads system. Some small clone of Google Ads. Here is diagram with common tables. Basically make it short, advertiser can have up to 10 variant of same campaign with different text variations, can geo-target his ads and unique impressions count only for IP that haven't been on certain site for more than 24 hours. Pretty simple but the question is what i lack in here from your experience because later it would much harder to fix design flaws and some of you probably done something alike also many SQL gurus in here so maybe i did over normalized DB or did not normalized as needed ? Second question is. My end goal is to get ads for user from ie. Germany that haven't seen same ad on same site for 24 hours as long as ads fit country of user. Each impression is count same as each click if there is one. I need to get 5 "random" ads based on IP, Country and higher CPC (pay per click). How can i achieve this with current design or maybe to design database the way it would be easy to get ads and show stats for advirtisers... thanks for any help...

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  • JMS MessageCreator.createMessage() in Grails

    - by Hans Wurst
    Hi there, I am trying to implement jms to my grails application. I have several JMS consumer in a spring based enviroment listining on an ActiveMQ broker. I wrote a simple test commandline client which creates messages and receives them in an request response manner. Here is the snippet that sends a MapMessage in Spring JMS way. This works for me as long I am in my spring world. final String corrID = UUID.randomUUID().toString(); asyncJmsTemplate.send("test.RequestQ", new MessageCreator() { public Message createMessage(Session session) throws JMSException { try { MapMessage msg = session.createMapMessage(); msg.setStringProperty("json", mapper.writeValueAsString(List<of some objects>)); msg.setJMSCorrelationID(corrID); msg.setJMSReplyTo(session.createQueue("test.ReplyQ")); return msg; } catch (JsonGenerationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (JsonMappingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } return null; } }); BUT when I tried to implement this methods to my grails test app I receive some METHOD_DEF exceptions. Sending simple TextMessages via the jmsTemplate.convertAndSende(Queue, Message) provided by the JMS Plugin works. Can any one help me? Is this a common problem? Cheers Hans

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  • How can I display a language according to the user's browser's language inside this code?

    - by janoChen
    How can I display a language according to the user's browser's language inside this mini-framework for my multilingual website? Basically, it has to display the default language of the user if there's no cookies. Example of index.php: (rendered output) <h2><?php echo l('tagline_h2'); ?></h2> common.php: (controller of which language to output) <?php session_start(); header('Cache-control: private'); // IE 6 FIX if(isSet($_GET['lang'])) { $lang = $_GET['lang']; // register the session and set the cookie $_SESSION['lang'] = $lang; setcookie("lang", $lang, time() + (3600 * 24 * 30)); } else if(isSet($_SESSION['lang'])) { $lang = $_SESSION['lang']; } else if(isSet($_COOKIE['lang'])) { $lang = $_COOKIE['lang']; } else { $lang = 'en'; } //use appropiate lang.xx.php file according to the value of the $lang switch ($lang) { case 'en': $lang_file = 'lang.en.php'; break; case 'es': $lang_file = 'lang.es.php'; break; case 'tw': $lang_file = 'lang.tw.php'; break; case 'cn': $lang_file = 'lang.cn.php'; break; default: $lang_file = 'lang.en.php'; } //translation helper function function l($translation) { global $lang; return $lang[$translation]; } include_once 'languages/'.$lang_file; ?> Example of /languages/lang.en.php: (where multilingual content is being stored) <?php $lang = array( 'tagline_h2' => '...',

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  • Fulltext search on many tables

    - by Rob
    I have three tables, all of which have a column with a fulltext index. The user will enter search terms into a single text box, and then all three tables will be searched. This is better explained with an example: documents doc_id name FULLTEXT table2 id doc_id a_field FULLTEXT table3 id doc_id another_field FULLTEXT (I realise this looks stupid but that's because I've removed all the other fields and tables to simplify it). So basically I want to do a fulltext search on name, a_field and another_field, and then show the results as a list of documents, preferably with what caused that document to be found, e.g. if another_field matched, I would display what another_field is. I began working on a system whereby three fulltext search queries are performed and the results inserted into a table with a structure like: search_results table_name row_id score (This could later be made to cache results for a few days with e.g. a hash of the search terms). This idea has two problems. The first is that the same document can be in the search results up to three times with different scores. Instead of that, if the search term is matched in two tables, it should have one result, but a higher score. The second is that parsing the results is difficult. I want to display a list of documents, but I don't immediately know the doc_id without a join of some kind; however the table to join to is dependant on the table_name column, and I'm not sure how to accomplish that. Wanting to search multiple related tables like this must be a common thing, so I guess what I'm asking is am I approaching this in the right way? Can someone tell me the best way of doing it please.

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  • Reference inherited class's <T>ype in a derived class

    - by DRapp
    I don't know if its possible or not, but here's what I need. I'm toying around with something and want to know if its possible since you can't create your own data type based on a sealed type such as int, Int32, Int64, etc. I want to create a top-level class that is defined of a given type with some common stuff. Then, derive this into two subclasses, but in this case, each class is based on either and int or Int64 type. From THAT instance, create an instance of either one and know its yped basis for parameter referenc / return settings. So when I need to create an instance of the "ThisClass", I don't have to know its type basis of either int or Int64, yet IT will know the type and be able to allow methods/functions to be called with the typed... This way, If I want to change my ThisClass definition from SubLevel1 to SubLevel2, I don't have to dance around all different data type definitions. Hope this makes sense.. public class TopLevel<T> { ... } pubic class SubLevel1 : TopLevel<int> { ... } public class SubLevel2 : TopLevel<Int64> { ... } public class ThisClass : SubLevel1 { ... public <based on the Int data type from SubLevel1> SomeFunc() { return <the Int value computed>; } }

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  • Design to distribute work when generating task oriented input for legacy dos application?

    - by TheDeeno
    I'm attempting to automate a really old dos application. I've decided the best way to do this is via input redirection. The legacy app (menu driven) has many tasks within tasks with branching logic. In order to easily understand and reuse the input for these tasks, I'd like to break them into bit size pieces. Since I'll need to start a fresh app on each run, repeating a context to consume a bit might be messy. I'd like to create an object model that: allows me to concentrate on the task at hand allows me to reuse common tasks from different start points prevents me from calling a task from the wrong start point To be more explicit, given I have the following task hierarchy: START A A1 A1a A1b A2 A2a B B1 B1a I'd like an object model that lets me generate an input file for task "A1b" buy using building blocks like: START -> do_A, do_A1, do_A1b but prevents me from: START -> do_A1 // because I'm assuming a different call chain from above This will help me write "do_A1b" because I can always assume the same starting context and will simplify writing "do_A1a" because it has THE SAME starting context. What patterns will help me out here? I'm using ruby at the moment so if dynamic language features can help, I'm game.

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  • What is the best way to attach static methods to classes rather than to instances of a class?

    - by John Gietzen
    If I have a method for calculating the greatest common divisor of two integers as: public static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } What would be the best way to attach that to the System.Math class? Here are the three ways I have come up with: public static int GCD(this int a, int b) { return b == 0 ? a : b.GCD(a % b); } // Lame... var gcd = a.GCD(b); and: public static class RationalMath { public static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } } // Lame... var gcd = RationalMath.GCD(a, b); and: public static int GCD(this Type math, int a, int b) { return b == 0 ? a : typeof(Math).GCD(b, a % b); } // Neat? var gcd = typeof(Math).GCD(a, b); The desired syntax is Math.GCD since that is the standard for all mathematical functions. Any suggestions? What should I do to get the desired syntax?

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  • How to implement Master-Detail with Multi-Selection in WPF?

    - by gehho
    Hi, I plan to create a typical Master-Detail scenario, i.e. a collection of items displayed in a ListView via DataBinding to an ICollectionView, and details about the selected item in a separate group of controls (TextBoxes, NumUpDowns...). No problem so far, actually I have already implemented a pretty similar scenario in an older project. However, it should be possible to select multiple items in the ListView and get the appropriate shared values displayed in the detail view. This means, if all selected items have the same value for a property, this value should be displayed in the detail view. If they do not share the same value, the corresponding control should provide some visual clue for the user indicating this, and no value should be displayed (or an "undefined" state in a CheckBox for example). Now, if the user edits the value, this change should be applied to all selected items. Further requirements are: MVVM compatibility (i.e. not too much code-behind) Extendability (new properties/types can be added later on) Does anyone have experience with such a scenario? Actually, I think this should be a very common scenario. However, I could not find any details on that topic anywhere. Thanks! gehho. PS: In the older project mentioned above, I had a solution using a subclass of the ViewModel which handles the special case of multi-selection. It checked all selected items for equality and returned the appropriate values. However, this approach had some drawbacks and somehow seemed like a hack because (besides other smelly things) it was necessary to break the synchronization between the ListView and the detail view and handle it manually.

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  • How to apply styles to all windows in WPF app?

    - by Brandon
    I have the following App.xaml file: <Application x:Class="MiniDeviceConfig.App" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" StartupUri="MiniDeviceConfig.xaml"> <Application.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="Button.xaml"/> <ResourceDictionary Source="CheckBox.xaml"/> <ResourceDictionary Source="ComboBox.xaml"/> <ResourceDictionary Source="Common.xaml"/> <ResourceDictionary Source="GroupBox.xaml"/> <ResourceDictionary Source="Label.xaml"/> <ResourceDictionary Source="LinkButton.xaml"/> <ResourceDictionary Source="ListBox.xaml"/> <ResourceDictionary Source="ListView.xaml"/> <ResourceDictionary Source="RadioButton.xaml"/> <ResourceDictionary Source="Tooltip.xaml"/> <ResourceDictionary Source="Window.xaml"/> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Application.Resources> In my application, my main window is MiniDeviceConfig.xaml (as seen above). In my Button.xaml file, I clearly set the button height to some obscene number. And, this size is reflected in my main window's buttons. However, some action on the main window triggers a modal window that has more buttons on it. I was expecting the same tall buttons but no such luck. How do I get the style to propagate into all windows in the application?

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  • Pros/Cons of MySQL vs Postgresql for production Ruby on Rails environment?

    - by cakeforcerberus
    I will soon be switching from sqlite3 to either postgres or mysql. What should I consider when making this decision? Is mysql more suited for Rails than postgres in some areas and/or vice versa? Or, as I somewhat suspect, does it not really matter either way? Another factor that might play into my decision is the availability of tools to data pump my test data from the sqlite3 db to my new one. Is there anything that ActiveRecord provides natively to do this or any decent plugins/gems to help with this task? BONUS: How do I pronounce "Postgresql" and sound like I know what I'm talking about? :) Thanks Greg Smith for providing the following link that shows the most common pronunciations: http://www.postgresql.org/community/survey.33 UPDATE: Reference this question for more: http://stackoverflow.com/questions/110927/do-you-recommend-postgresql-over-mysql FYI: I ended up using MySQL. There is a neat plugin called yamldb that really saved me some time with the data transfer from my sqlite db to my new mysql one. Instructions on how to install and use it can be found here: http://accidentaltechnologist.com/ruby/change-databases-in-rails-with-yamldb/ Thanks Tom

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  • How do I unit test a finalizer?

    - by GraemeF
    I have the following class which is a decorator for an IDisposable object (I have omitted the stuff it adds) which itself implements IDisposable using a common pattern: public class DisposableDecorator : IDisposable { private readonly IDisposable _innerDisposable; public DisposableDecorator(IDisposable innerDisposable) { _innerDisposable = innerDisposable; } #region IDisposable Members public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } #endregion ~DisposableDecorator() { Dispose(false); } protected virtual void Dispose(bool disposing) { if (disposing) _innerDisposable.Dispose(); } } I can easily test that innerDisposable is disposed when Dispose() is called: [Test] public void Dispose__DisposesInnerDisposable() { var mockInnerDisposable = new Mock<IDisposable>(); new DisposableDecorator(mockInnerDisposable.Object).Dispose(); mockInnerDisposable.Verify(x => x.Dispose()); } But how do I write a test to make sure innerDisposable does not get disposed by the finalizer? I want to write something like this but it fails, presumably because the finalizer hasn't been called by the GC thread: [Test] public void Finalizer__DoesNotDisposeInnerDisposable() { var mockInnerDisposable = new Mock<IDisposable>(); new DisposableDecorator(mockInnerDisposable.Object); GC.Collect(); mockInnerDisposable.Verify(x => x.Dispose(), Times.Never()); }

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  • Regressing panel data in SAS.

    - by John
    Hey Guys, thanks to your help I succesfully managed all my databases! I am now looking at a panel data set on which I have to regress. Since I only started my Phd this semester together with the econometrics courses I am still new to many statistic applications and regression methods. I want to do a simple regression as in Y = x1 x2 x3 etc, now I already browsed through some literature and found that for panel data it's common to do a fixed effects regression. Also, my Y variable only has positive values so I was thinking in the direction of a Tobit model? I'm doing some research concerning the coverage of analysts in the financial business. My independent variable is the coverage of analysts on a certain firm, so per observation i have 1 analyst and 1 firm, together with different characteristics(market cap and betas etc) of the firm. All this data is monthly. As coverage cannot become negative (only 0) I was thinking of a Tobit model? Do you guys have any ideas what would be a good regression method? Or have some good sources (e books, written books, through university I have access to almost anything concerning my field of work) of information (cause I do have to learn these things for future research)? Thanks!

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  • Why is an Add method required for { } initialization?

    - by Dan Tao
    To use initialization syntax like this: var contacts = new ContactList { { "Dan", "[email protected]" }, { "Eric", "[email protected]" } }; ...my understanding is that my ContactList type would need to define an Add method that takes two string parameters: public void Add(string name, string email); What's a bit confusing to me about this is that the { } initializer syntax seems most useful when creating read-only or fixed-size collections. After all it is meant to mimic the initialization syntax for an array, right? (OK, so arrays are not read-only; but they are fixed size.) And naturally it can only be used when the collection's contents are known (at least the number of elements) at compile-time. So it would almost seem that the main requirement for using this collection initializer syntax (having an Add method and therefore a mutable collection) is at odds with the typical case in which it would be most useful. I'm sure I haven't put as much thought into this matter as the C# design team; it just seems that there could have been different rules for this syntax that would have meshed better with its typical usage scenarios. Am I way off base here? Is the desire to use the { } syntax to initialize fixed-size collections not as common as I think? What other factors might have influenced the formulation of the requirements for this syntax that I'm simply not thinking of?

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  • mercurial: how to synchronize mq patches from a master repo as mq patches to a set of clone repos

    - by dim
    I have to run a dozen of different build tests on a code base maintained in a mercurial repository. I don't want to run serially these tests on same repository because they modify a set of common files and I want to run them in parallel on different machines. Also, after all tests are run I want to have access to latest test results from those test work areas. Currently I'm cloning the master repository a dozen of times and run in each clone one different test. Before each test execution I do a pull/update/purge preparation sequence in order to start the test on latest clean state. That's good for me. I'm also preparing new changes using mq extension that I would test on all clones as above before committing them. For testing some ready candidate mq patches I want somehow to deploy/synchronize them to be available in test clones and apply those ready for testing using some guard before running the test. Did anybody do this synchronization before? What's the most simple way to do it? Do I need to have versioned mq patches for that?

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  • Simple grid layout question

    - by Matt H.
    I can't believe I'm back to this after working with WPF for 3 months :) Consider very common setup: How do I configure the rowheights so that the top and bottom rows (menu bar and status bar) size to fit the height of their content, and the middle row (main content), fills the remaining available space in the program? I can't fix the height of the top/bottom rows because the height of their content can vary. <Window> <Grid> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition/> <RowDefinition/> </Grid.RowDefinitions> <Menu Grid.Row=0> ...menuitems </Menu> <Grid Grid.Row=1> ...main application content here (like most programs) </Grid> <StatusBar> ...statusbaritems </StatusBar> </Grid> </Window>

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  • F# passing an operator with arguments to a function

    - by dan
    Can you pass in an operation like "divide by 2" or "subtract 1" using just a partially applied operator, where "add 1" looks like this: List.map ((+) 1) [1..5];; //equals [2..6] // instead of having to write: List.map (fun x-> x+1) [1..5] What's happening is 1 is being applied to (+) as it's first argument, and the list item is being applied as the second argument. For addition and multiplication, this argument ordering doesn't matter. Suppose I want to subtract 1 from every element (this will probably be a common beginners mistake): List.map ((-) 1) [1..5];; //equals [0 .. -4], the opposite of what we wanted 1 is applied to the (-) as its first argument, so instead of (list_item - 1), I get (1 - list_item). I can rewrite it as adding negative one instead of subtracting positive one: List.map ((+) -1) [1..5];; List.map (fun x -> x-1) [1..5];; // this works too I'm looking for a more expressive way to write it, something like ((-) _ 1), where _ denotes a placeholder, like in the Arc language. This would cause 1 to be the second argument to -, so in List.map, it would evaluate to list_item - 1. So if you wanted to map divide by 2 to the list, you could write: List.map ((/) _ 2) [2;4;6] //not real syntax, but would equal [1;2;3] List.map (fun x -> x/2) [2;4;6] //real syntax equivalent of the above Can this be done or do I have to use (fun x -> x/2)? It seems that the closest we can get to the placeholder syntax is to use a lambda with a named argument.

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