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• XPath - get parent node

  - by chris.shi

  //* [ local-name()='component' and namespace-uri()='urn:hl7-org:v3' ] using thispath ,I can get a node like this: <component xmlns="urn:hl7-org:v3"> <structuredBody> <component> <section> <code code="10164-2" codeSystem="2.16.840.1.113883.6.1" codeSystemName="LOINC"/> <title>History of Present Illness</title> <text> </text> </section> </component> <component> ...... </component> <component> ...... </component> <structuredBody/> <component/> in order to get the node as below: <component> <section> <code code="10164-2" codeSystem="2.16.840.1.113883.6.1" codeSystemName="LOINC"/> <title>History of Present Illness</title> <text> </text> </section> </component> I change the path to : //* [ local-name()='component' and namespace-uri()='urn:hl7-org:v3' and position()=1] but ,how can I get the same result by using [code="10164-2"] as a qualification. ( I do not know how to describe this question ,as a result ,the title of this question is a little simple ,sorry .) thanks

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• How are you using C++0x today? [closed]

  - by Roger Pate

  This is a question in two parts, the first is the most important and concerns now: Are you following the design and evolution of C++0x? What blogs, newsgroups, committee papers, and other resources do you follow? Even where you're not using any new features, how have they affected your current choices? What new features are you using now, either in production or otherwise? The second part is a follow-up, concerning the new standard once it is final: Do you expect to use it immediately? What are you doing to prepare for C++0x, other than as listed for the previous questions? Obviously, compiler support must be there, but there's still co-workers, ancillary tools, and other factors to consider. What will most affect your adoption? Edit: The original really was too argumentative; however, I'm still interested in the underlying question, so I've tried to clean it up and hopefully make it acceptable. This seems a much better avenue than duplicating—even though some answers responded to the argumentative tone, they still apply to the extent that they addressed the questions, and all answers are community property to be cleaned up as appropriate, too.

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• POST XML to server, receive PDF

  - by Shaggy Frog

  Similar to this question, we are developing a Web app where the client clicks a button to receive a PDF from the server. Right now we're using the .ajax() method with jQuery to POST the data the backend needs to generate the PDF (we're sending XML) when the button is pressed, and then the backend is generating the PDF entirely in-memory and sending it back as application/pdf in the HTTP response. One answer to that question requires the server-side save the PDF to disk so it can give back a URL for the client to GET. But I don't want the backend caching content at all. The other answer suggests the use of a jQuery plugin, but when you look at its code, it's actually generating a form element and then submitting the form. That method will not work for us since we are sending XML data in the body of the HTTP request. Is there a way to have the browser open up the PDF without caching the PDF server-side, and without requiring us to throw out our send-data-to-the-server-using-XML solution? (I'd like the browser to behave like it does when a form element is submitted -- a POST is made and then the browser looks at the Content-type header to determine what to do next, like load the PDF in the browser window, a la Safari)

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• C++ operator new, object versions, and the allocation sizes

  - by mizubasho

  Hi. I have a question about different versions of an object, their sizes, and allocation. The platform is Solaris 8 (and higher). Let's say we have programs A, B, and C that all link to a shared library D. Some class is defined in the library D, let's call it 'classD', and assume the size is 100 bytes. Now, we want to add a few members to classD for the next version of program A, without affecting existing binaries B or C. The new size will be, say, 120 bytes. We want program A to use the new definition of classD (120 bytes), while programs B and C continue to use the old definition of classD (100 bytes). A, B, and C all use the operator "new" to create instances of D. The question is, when does the operator "new" know the amount of memory to allocate? Compile time or run time? One thing I am afraid of is, programs B and C expect classD to be and alloate 100 bytes whereas the new shared library D requires 120 bytes for classD, and this inconsistency may cause memory corruption in programs B and C if I link them with the new library D. In other words, the area for extra 20 bytes that the new classD require may be allocated to some other variables by program B and C. Is this assumption correct? Thanks for your help.

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• Auto filling polymorphic table on save or on delete in django

  - by Mo J. Mughrabi

  Hi, Am working on an project in which I made an app "core" it will contain some of the reused models across my projects, most of those are polymorphic models (Generic content types) and will be linked to different models. Example below am trying to create audit model and will be linked to several models which may require auditing. This is the polls/models.py from django.db import models from django.contrib.auth.models import User from core.models import * from django.contrib.contenttypes import generic class Poll(models.Model): ## TODO: Document question = models.CharField(max_length=300) question_slug=models.SlugField(editable=False) start_poll_at = models.DateTimeField(null=True) end_poll_at = models.DateTimeField(null=True) is_active = models.BooleanField(default=True) audit_obj=generic.GenericRelation(Audit) def __unicode__(self): return self.question class Choice(models.Model): ## TODO: Document choice = models.CharField(max_length=200) poll=models.ForeignKey(Poll) audit_obj=generic.GenericRelation(Audit) class Vote(models.Model): ## TODO: Document choice=models.ForeignKey(Choice) Ip_Address=models.IPAddressField(editable=False) vote_at=models.DateTimeField("Vote at", editable=False) here is the core/modes.py from django.db import models from django.contrib.auth.models import User from django.contrib.contenttypes.models import ContentType from django.contrib.contenttypes import generic class Audit(models.Model): ## TODO: Document # Polymorphic model using generic relation through DJANGO content type created_at = models.DateTimeField("Created at", auto_now_add=True) created_by = models.ForeignKey(User, db_column="created_by", related_name="%(app_label)s_%(class)s_y+") updated_at = models.DateTimeField("Updated at", auto_now=True) updated_by = models.ForeignKey(User, db_column="updated_by", null=True, blank=True, related_name="%(app_label)s_%(class)s_y+") content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField(unique=True) content_object = generic.GenericForeignKey('content_type', 'object_id') and here is polls/admin.py from django.core.context_processors import request from polls.models import Poll, Choice from core.models import * from django.contrib import admin class ChoiceInline(admin.StackedInline): model = Choice extra = 3 class PollAdmin(admin.ModelAdmin): inlines = [ChoiceInline] admin.site.register(Poll, PollAdmin) Am quite new to django, what am trying to do here, insert a record in audit when a record is inserted in polls and then update that same record when a record is updated in polls.

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• How can I make this LinqToSQL query work? (SqlExecption)

  - by kversch

  The following code gives me an SqlException: OO theCourse = subject.Course; var students = dc.studentsCourses.Where(x = x.course == theCourse).Select(x = x.student); "Invalid object name 'dbo.studentsCourses'." I tried the following code instead but I also get an Exception. My original question was asked on Aardvark and can be read bellow: var allStudents = from s in dc.students select s; List thestudents = new List(); foreach (student s in allStudents) { if (s.courses.Contains(theCourse)) { thestudents.Add(s); } } I did a right click, "run custom tool" on my dbml and checked my names of my tables and entities. The project compiles but I get an Exception at runtime on this line: "if (s.courses.Contains(theCourse))" Any ideas? Original question on Aardvark: How do I do a LinqToSQL query that gives me this: I want to select all students that attended a certain lesson. The lesson is from a certain course. So select the course the lesson is from. Now select all the students that are following that course. There is a many-to-many relationship between the students and the courses table in my DB. I already extended my LINQ entities to be able to select student.Courses and course.Students using this method: http://www.codeproject.com/KB/linq/linq-to-sql-many-to-many.aspx

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• R : remove columns from dataframe where ALL values are NA

  - by Sophomore

  hello everybody! I'm having some trouble with my huge data frame and couldn't really resolve that question myself: The dataframe has some properties as columns and each row represents one data set. I've done some sanatizing to this dataframe (e.g. get rid of datasets which are not to be included in evaluation). (Whoever might be interested: Beforehand I aggregate around 5000 single text files and put them in a tsv, some of the proerties have a sequence number like "button.pressed.1" ... ""button.pressed.n". Some of the sets excluded had really high numbers for n but got excluded, all sets left have much smaller numbers for n but the property "button.presed.50" is still there and all remaining sets have an NA in that column. Actually its a different property but the example should clarify my intention...) So the question is quite simple (for some sophisticated R pro): I need to get rid of columns where for ALL rows the value is NA. Could someone please help me out? (All I have managed to get rid of columns where at least one NA exists which dropped about half my columns)...

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• UIAlertView choice causing resignFirstResponder to fail

  - by Chazbot

  Hi everyone. I'm having a similar issue to Anthony Chan's question, and after trying every suggested solution, I'm still stuck. Somehow, only after interacting with my UIAlertView, I'm unable to dismiss the keyboard in another view of my app. It's as though the Alert is breaking my UITextField's ability to resignFirstResponder. Below I instantiate my UIAlertView, which then calls its didDismissWIthButtonIndex method. Then, I call the showInfo method, which loads another UIViewController. UIAlertView *emailFailAlert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"error message text." delegate:self cancelButtonTitle:@"Not now" otherButtonTitles:@"Settings", nil]; [emailFailAlert setTag:2]; [emailFailAlert show]; [emailFailAlert release]; Once the 'Settings' option is pressed, I'm calling this method: - (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex { if ([alertView tag] == 2) { if (buttonIndex == 1){ [self showInfo:nil]; } } } My showInfo method loads the other ViewController, via the code below: - (IBAction)showInfo:(id)sender { FlipsideViewController *fscontroller = [[FlipsideViewController alloc] initWithNibName:@"FlipsideView" bundle:nil]; fscontroller.delegate = self; fscontroller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController:fscontroller animated:YES]; [fscontroller release]; } Upon clicking any textField in this Flipside VC, I'm unable to dismiss the keyboard as I normally can with - (BOOL)textFieldShouldReturn:(UITextField *)textField, and [textField resignFirstResponder]. I've omitted this code bc this question is getting long, but I'm happy to post if necessary. The interesting part is that if I comment out the [self showInfo:nil] call made when the button is clicked and call it by clicking a test button (outside the alertView didDismissWithButtonIndex: method), everything works fine. Any idea what's happening here? Thanks in advance!

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• Entity Framework in layered architecture

  - by Kamyar

  I am using a layered architecture with the Entity Framework. Here's What I came up with till now (All the projects Except UI are class library): Entities: The POCO Entities. Completely persistence ignorant. No Reference to other projects. Generated by Microsoft's ADO.Net POCO Entity Generator. DAL: The EDMX (Entity Model) file with the context class. (t4 generated). References: Entities BLL: Business Logic Layer. Will implement repository pattern on this layer. References: Entities, DAL. This is where the objectcontext gets populated: var ctx=new DAL.MyDBEntities(); UI: The presentation layer: ASP.NET website. References: Entities, BLL + a connection string entry to entities in the config file (question #2). Now my three questions: Is my layer discintion approach correct? In my UI, I access BLL as follows: var customerRep = new BLL.CustomerRepository(); var Customer = customerRep.GetByID(myCustomerID); The problem is that I have to define the entities connection string in my UI's web.config/app.config otherwise I get a runtime exception. IS defining the entities connectionstring in UI spoils the layers' distinction? Or is it accesptible in a muli layered architecture. Should I take any additional steps to perform chage tracking, lazy loading, etc (by etc I mean the features that Entity Framework covers in a conventional, 1 project, non POCO code generation)? Thanks and apologies for the lengthy question.

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• forward invocation, by hand vs magically?

  - by John Smith

  I have the following two class: //file FruitTree.h @interface FruitTree : NSObject { Fruit * f; Leaf * l; } @end //file FruitTree.m @implementation FruitTree //here I get the number of seeds from the object f @end //file Fruit @interface Fruit : NSObject { int seeds; } -(int) countfruitseeds; @end My question is at the point of how I request the number of seeds from f. I have two choices. Either: Since I know f I can explicitly call it, i.e. I implement the method -(int) countfruitseeds { return [f countfruitseeds]; } Or: I can just use forwardInvocation: - (NSMethodSignature *)methodSignatureForSelector:(SEL)selector { // does the delegate respond to this selector? if ([f respondsToSelector:selector]) return [f methodSignatureForSelector:selector]; else if ([l respondsToSelector:selector]) return [l methodSignatureForSelector:selector]; else return [super methodSignatureForSelector: selector]; } - (void)forwardInvocation:(NSInvocation *)invocation { [invocation invokeWithTarget:f]; } (Note this is only a toy example to ask my question. My real classes have lots of methods, which is why I am asking.) Which is the better/faster method?

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• Should a Trim method generally in the Data Access Layer or with in the Domain Layer?

  - by jpierson

  I'm dealing with a database that contains data with inconsistencies such as white leading and trailing white space. In general I see a lot of developers practice defensive coding by trimming almost all strings that come from the database that may have been entered by a user at some point. In my oppinoin it is better to do such formating before data is persisted so that it is done only once and then the data can be in a consistent and reliable state. Unfortunatley this is not the case however which leads me to the next best solution, using a Trim method. If I trim all data as part of my data access layer then I don't have to concern myself with defensive trimming within the business objects of my domain layer. If I instead put the trimming responsibility in my business objects, such as with set accessors of my C# properties, I should get the same net results however the trim will be operating on all values assigned to my business objects properties not just the ones that come from the inconsistent database. I guess as a somewhat philisophical question that may determine the answer I could ask "Should the domain later be responsible for defensive/coercive formatting of data?" Would it make sense to have a set accessor for a PhoneNumber property on a business object accept a unformatted or formatted string and then attempt to format it as required or should this responsibility be pushed to the presentation and data access layers leaving the domain layer more strict in the type of data that it will accept? I think this may be the more fundamental question. Update: Below are a few links that I thought I should share about the topic of data cleansing. Information service patterns, Part 3: Data cleansing pattern LINQ to SQL - Format a string before saving? How to trim values using Linq to Sql?

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• How to create platform independent 3D video on 3D TV via HDMI 1.4?

  - by artif

  I am writing a real-time, interactive 3D visualization program and at each point in the program, I can compute 2 images (bitmaps) that are meant to look 3D together by means of stereoscopy. How do I get my program to display the image pairs such that they look 3D on a 3D TV? Is there a platform independent way of accomplishing it? (By platform I mean independent of GPU brand, operating system, 3D TV vendor, etc.) If not, which is preferable-- to lock in by GPU, OS, or 3D TV? I suppose I need to be using an HDMI 1.4 cable with the 3D TV? HDMI 1.4 can encode stereoscopy via side-by-side method. But how do I send such an encoded signal to the monitor? What kind of libraries do I use for this sort of thing? Windows DirectShow? If DirectShow is correct, is there a cross platform equivalent available? If anyone asks, yes I have seen this question: http://stackoverflow.com/questions/2811350/generating-3d-tv-stereoscopic-output-programmatically. However, correct me if I am wrong, it does not appear to be what I'm looking for. I do not have an OpenGL or Direct3D program that generates polygons, for which a Nvidia card can do ad-hoc impromptu stereoscopy simply by rendering the scene from 2 slightly offset points of view and then displaying those 2 images on the monitor-- my program already has those image pairs and needs to display them (and they are not the result of rendering polygons). Btw, I have never done any major multimedia programming before and know very little about HDMI, Direct Show, 3D TVs, etc so pardon me if any parts of this question did not make any sense at all.

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• Opengl: fit a quad to screen, given the value of Z.

  - by hytparadisee

  Short Version of the question: I will put a quad. I know the width and height of the screen in window coordinates, i know the Z-coordinates of the quad in 3D. I know the FOVY, I know the aspect. The quad will be put along Z-axis, My camera doesn't move (placed at 0, 0, 0). I want to find out the width and height of the quad IN 3D COORDINATES that will fit exactly onto my screen. Long Version of the question: I would like to put a quad along the Z-axis at the specified offset Z, I would like to find out the width and height of the quad that will exactly fill the entire screen. I used to have a post on gamedev.net that uses a formula similar to the following: *dist = Z * tan ( FOV / 2 )* Now I can never find the post! Though it's similar, it is still different, because I remembered in that working formula, they do make use of screenWidth and screenHeight, which are the width and height of the screen in window coordinates. I am not really familiar with concepts like frustum, fov and aspect so that's why I can't work out the formula on my own. Besides, I am sure I don't need gluUnproject (I tried it, but the results are way off). It's not some gl calls, it's just a math formula that can find out the width and height in 3D space that can fill the entire screen, IF Z offset, width in window coordinates, and height in window coordinates, are known. Thanks all in advance.

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• What do we log and why do we log it?

  - by Lucas

  This has been bugging me for quite some time. Reading various questions on SO, blogs and listening to colleagues, I keep hearing how important "logging" is. How various logging frameworks stack up against each other, and how there are so many to pick from it's (apparently) ridiculous. Now, I know what logging is. What I don't know is what is supposed to be logged and why. Sure, I can guess. Exceptions? Sounds like something one might want to log... but which exceptions? And is it only exceptions? And what do I do with the logged information? If it's an in-house app, then that could probably be put to good use, but if it's a commercial desktop application, how is the log of... whatever... helping anyone? I doubt regular users would be peeking inside. Is it then something you ask the users to provide on request? I'm deeply frustrated by my own ignorance in this. It's also surprising how little information there is about this. The info on the websites of the various logging frameworks is all written for an audience that already knows what it wants to log, and knows why it needs to do so. Same things goes for the various discussions on SO about logging, like for instance this highly voted up question on Logging best practices. For a question with so many votes, it's almost comical how there's next to nothing in there that would answer my what and why questions. So being finally fed up, I'm asking here: what do people log, and why do they log it?

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• Is there a standard pattern for scanning a job table executing some actions?

  - by Howiecamp

  (I realize that my title is poor. If after reading the question you have an improvement in mind, please either edit it or tell me and I'll change it.) I have the relatively common scenario of a job table which has 1 row for some thing that needs to be done. For example, it could be a list of emails to be sent. The table looks something like this: ID Completed TimeCompleted anything else... ---- --------- ------------- ---------------- 1 No blabla 2 No blabla 3 Yes 01:04:22 ... I'm looking either for a standard practice/pattern (or code - C#/SQL Server preferred) for periodically "scanning" (I use the term "scanning" very loosely) this table, finding the not-completed items, doing the action and then marking them completed once done successfully. In addition to the basic process for accomplishing the above, I'm considering the following requirements: I'd like some means of "scaling linearly", e.g. running multiple "worker processes" simultaneously or threading or whatever. (Just a specific technical thought - I'm assuming that as a result of this requirement, I need some method of marking an item as "in progress" to avoid attempting the action multiple times.) Each item in the table should only be executed once. Some other thoughts: I'm not particularly concerned with the implementation being done in the database (e.g. in T-SQL or PL/SQL code) vs. some external program code (e.g. a standalone executable or some action triggered by a web page) which is executed against the database Whether the "doing the action" part is done synchronously or asynchronously is not something I'm considering as part of this question.

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• Fast, easy, and secure method to perform DB actions with GET

  - by rob - not a robber

  Hey All, Sort of a methods/best practices question here that I am sure has been addressed, yet I can't find a solution based on the vague search terms I enter. I know starting off the question with "Fast and easy" will probably draw out a few sighs, so my apologies. Here is the deal. I have a logged in area where an ADMIN can do a whole host of POST operations to input data relating to their profile. The way I have data structured is pretty distinct and well segmented in most tables as it relates to the ID of the admin. Now, I have a table where I dump one type of data into and differentiate this data by assigning the ADMIN's unique ID to each record. In other words, all ADMINs have this one type of data writing to this table. I just differentiate by the ADMIN ID with each record. I was planning on letting the ADMIN remove these records by clicking on a link with a query string - obviously using GET. Obviously, the query structure is in the link so any logged in admin could then exploit the URL and delete a competitor's records. Is the only way to safely do this through POST or should I pass through the session info that includes password and validate it against the ADMIN ID that is requesting the delete? This is obviously much more work for me. As they said in the auto repair biz I used to work in... there are 3 ways to do a job: Fast, Good, and Cheap. You can only have two at a time. Fast and cheap will not be good. Good and cheap will not have fast turnaround. Fast and good will NOT be cheap. haha I guess that applies here... can never have Fast, Easy and Secure all at once ;) Thanks in advance...

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• CSS3 animations - how to make different animations to different elements on scroll

  - by DeanDeey

  I have a question about the doing CSS3 animations on scroll.. I found a code, that shows the DIV element after the user scrolls down: <script type="text/javascript"> $(document).ready(function() { /* Every time the window is scrolled ... */ $(window).scroll( function(){ /* Check the location of each desired element */ $('.hideme').each( function(i){ var bottom_of_object = $(this).position().top + $(this).outerHeight(); var bottom_of_window = $(window).scrollTop() + $(window).height(); /* If the object is completely visible in the window, fade it it */ if( bottom_of_window > bottom_of_object ){ $(this).animate({'opacity':'1'},500); } }); }); }); </script> I'm building a site, which one will have about 5 different boxes, which one will be shown when the user scrolls down to each box. But my question is, how i make the animation inside those boxes. Foe example: in each box there is title, content and images. How do i make all the elements appear after each other, because with this code all the class elements are shown at once. But i would like that if user scrolls down, first the tittle appears, then the content and at the end the images. And then when user scrolls to the next box, the same process repeat's itself. I use some CSS3 delays, but in this case i don't know how long will user take to scroll down. thanks!

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• Corrupt UTF-8 Characters with PHP 5.2.10 and MySQL 5.0.81

  - by jkndrkn

  We have an application hosted on both a local development server and a live site. We are experiencing UTF-8 corruption issues and are looking to figure out how to resolve them. The system is run using symfony 1.0 with Propel. On our development server, we are running PHP 5.2.0 and MySQL 5.0.32. We do not experience corrupted UTF-8 characters there. On our live site, PHP 5.2.10 and MySQL 5.0.81 is running. On that server, certain characters such as ô´ and S are corrupted once they are stored in the database. The corrupted characters are showing up as either question marks or approximations of the original character with adjacent question marks. Examples of corruption: Uncorrupted: ô´ Corrupted: ô? Uncorrupted: S Corrupted: ? We are currently using the following techniques on both development and live servers: Executing the following queries prior to execution of any other queries: SET NAMES 'utf8' COLLATE 'utf8_unicode_ci' SET CHARSET 'utf8' Setting the <meta> Content-Type value to: <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> Adding the following to our .htaccess file: AddDefaultCharset utf-8 Using mb_* (multibyte) PHP functions where necessary. Being sure to set database columns to use utf8_unicode_ci collation. These techniques are sufficient for our development site, but do not work on the live site. On the live site I've also tried adding mysql_set_encoding('ut8', $mysql_connection) but this does not help either. I have found some evidence that newer versions of PHP and MySQL are mishandling UTF-8 character encodings.

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• Calling a subclass method from a superclass

  - by Shaun

  Preface: This is in the context of a Rails application. The question, however, is specific to Ruby. Let's say I have a Media object. class Media < ActiveRecord::Base end I've extended it in a few subclasses: class Image < Media def show # logic end end class Video < Media def show # logic end end From within the Media class, I want to call the implementation of show from the proper subclass. So, from Media, if self is a Video, then it would call Video's show method. If self is instead an Image, it would call Image's show method. Coming from a Java background, the first thing that popped into my head was 'create an abstract method in the superclass'. However, I've read in several places (including Stack Overflow) that abstract methods aren't the best way to deal with this in Ruby. With that in mind, I started researching typecasting and discovered that this is also a relic of Java thinking that I need to banish from my mind when dealing with Ruby. Defeated, I started coding something that looked like this: def superclass_method # logic this_media = self.type.constantize.find(self.id) this_media.show end I've been coding in Ruby/Rails for a while now, but since this was my first time trying out this behavior and existing resources didn't answer my question directly, I wanted to get feedback from more-seasoned developers on how to accomplish my task. So, how can I call a subclass's implementation of a method from the superclass in Rails? Is there a better way than what I ended up (almost) implementing?

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• Declaration, allocation and assignment of an array of pointers to function pointers

  - by manneorama

  Hello Stack Overflow! This is my first post, so please be gentle. I've been playing around with C from time to time in the past. Now I've gotten to the point where I've started a real project (a 2D graphics engine using SDL, but that's irrelevant for the question), to be able to say that I have some real C experience. Yesterday, while working on the event system, I ran into a problem which I couldn't solve. There's this typedef, //the void parameter is really an SDL_Event*. //but that is irrelevant for this question. typedef void (*event_callback)(void); which specifies the signature of a function to be called on engine events. I want to be able to support multiple event_callbacks, so an array of these callbacks would be an idea, but do not want to limit the amount of callbacks, so I need some sort of dynamic allocation. This is where the problem arose. My first attempt went like this: //initial size of callback vector static const int initial_vecsize = 32; //our event callback vector static event_callback* vec = 0; //size static unsigned int vecsize = 0; void register_event_callback(event_callback func) { if (!vec) __engine_allocate_vec(vec); vec[vecsize++] = func; //error here! } static void __engine_allocate_vec(engine_callback* vec) { vec = (engine_callback*) malloc(sizeof(engine_callback*) * initial_vecsize); } First of all, I have omitted some error checking as well as the code that reallocates the callback vector when the number of callbacks exceed the vector size. However, when I run this code, the program crashes as described in the code. I'm guessing segmentation fault but I can't be sure since no output is given. I'm also guessing that the error comes from a somewhat flawed understanding on how to declare and allocate an array of pointers to function pointers. Please Stack Overflow, guide me.

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• Multiple websites, Single sign-on design

  - by Yannis

  Hi all, I have a question. A client I have been doing some work recently has a range of websites with different login mechanisms. He is looking to slowly migrate to a single sign-on mechanism for his websites (all written in asp.net mvc). I am looking at my options here, so here is a list of requirements: 1) It has to be secure (duh) 2) It needs to support extra user properties over and above the usual name, address stuff (such as money or credits for a user) 3) It has to provide a centralized user management web console for his convenience (I understand that this will be a small project on top of whatever design solution I choose to go for) 4) It has to integrate with the existing websites without re-engineering the whole product (I understand that this depends on the current product implementation). 5) It has to deal with emailing the user when he registers (in order for him to activate his account) 6) It has to deal with activating the user when he clicks the activate me link in the email (I understand that 5 and 6 require some form of email templating system to support different emails per application) I was thinking of creating a library working together with forms authentication that exposes whatever methods are required (e.g. login, logout, activate, etc. and a small restful service to implement activation from email, registration processing etc. Taking into account that loads of things have been left out to make this question brief and to the point, does this sound like a good design? But this looks like a very common problem so arent there any existing projects that I could use? Thanks for reading.

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• How can I write a unit test to determine whether an object can be garbage collected?

  - by driis

  In relation to my previous question, I need to check whether a component that will be instantiated by Castle Windsor, can be garbage collected after my code has finished using it. I have tried the suggestion in the answers from the previous question, but it does not seem to work as expected, at least for my code. So I would like to write a unit test that tests whether a specific object instance can be garbage collected after some of my code has run. Is that possible to do in a reliable way ? EDIT I currently have the following test based on Paul Stovell's answer, which succeeds: [TestMethod] public void ReleaseTest() { WindsorContainer container = new WindsorContainer(); container.Kernel.ReleasePolicy = new NoTrackingReleasePolicy(); container.AddComponentWithLifestyle<ReleaseTester>(LifestyleType.Transient); Assert.AreEqual(0, ReleaseTester.refCount); var weakRef = new WeakReference(container.Resolve<ReleaseTester>()); Assert.AreEqual(1, ReleaseTester.refCount); GC.Collect(); GC.WaitForPendingFinalizers(); Assert.AreEqual(0, ReleaseTester.refCount, "Component not released"); } private class ReleaseTester { public static int refCount = 0; public ReleaseTester() { refCount++; } ~ReleaseTester() { refCount--; } } Am I right assuming that, based on the test above, I can conclude that Windsor will not leak memory when using the NoTrackingReleasePolicy ?

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• Catching specific vs. generic exceptions in c#

  - by Scott Vercuski

  This question comes from a code analysis run against an object I've created. The analysis says that I should catch a more specific exception type than just the basic Exception. Do you find yourself using just catching the generic Exception or attempting to catch a specific Exception and defaulting to a generic Exception using multiple catch blocks? One of the code chunks in question is below: internal static bool ClearFlags(string connectionString, Guid ID) { bool returnValue = false; SqlConnection dbEngine = new SqlConnection(connectionString); SqlCommand dbCmd = new SqlCommand("ClearFlags", dbEngine); SqlDataAdapter dataAdapter = new SqlDataAdapter(dbCmd); dbCmd.CommandType = CommandType.StoredProcedure; try { dbCmd.Parameters.AddWithValue("@ID", ID.ToString()); dbEngine.Open(); dbCmd.ExecuteNonQuery(); dbEngine.Close(); returnValue = true; } catch (Exception ex) { ErrorHandler(ex); } return returnValue; } Thank you for your advice EDIT: Here is the warning from the code analysis Warning 351 CA1031 : Microsoft.Design : Modify 'ClearFlags(string, Guid)' to catch a more specific exception than 'Exception' or rethrow the exception

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• How to manage data access / preloading efficiently using web services in C# ?

  - by Amadeus45

  Hello all, Ok, this is very "generic" question. We currently have a SQL Server database for which we need to develop an application in ASP.NET with will contain all the business logic in C# Web Services. The thing is that, architecturally speaking, I'm not sure how to design the web service and the data management. There are many things to consider : We need have very rapid access to data. Right now, we have over a million "sales" and "purchases" record from which we need to often calculate and load the current stock for a given day according to a serie of parameter. I'm not sure how we should preload the data and keep the data in the Web Service. Doing a stock calculation within a SQL query will be very lengthy. They currently have a stock calculation application that preloads all sales and purchases for the day and afterwards calculate the stock on the code-side. We want to develop powerful reporting tools. We want to implement a "pivot table" but not sure how to implement it and have good performances. For the reasons above, I'm not sure how to design the data model. Anybody can give me any guidelines on how to start, or from their personnal experiences (what have you done in the past ?) I'm not sure if it's possible to make a bounty even though the question is new (I'd put 300 rep on it, since I really need something). If you know how, let me know. Thanks

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• ADO.NET Multiple simultaneous reads from an open database.

  - by Deverill

  Answer not needed - my logic was wrong and this question is invalid. Charles helped me see where I went off-tracks. Thanks I have a utility that moves data from one source to another. In the process of writing the record I check to see if it exists and do an update/insert as necessary. The difficulty I have is that as I'm writing the main record info there is a 2nd table for "custom data" that I have to check to see if it exists and do an update/insert for that as well. Example: I may be loading a pencil sharpener that may or may not exist. While I'm writing it into destination it has characteristics such as style, color, etc. and each of them may or may not exist. As written I seem to need to have 2 DataReaders open, one for the sharpener and one to check for and update color. I am new to ADO.NET, but not to programming and it's more complicated than I listed but for sanity's sake I didn't put all the details. My question is: What am I missing? You can't have 2 readers open at the same time on a connection, yet I can't close the first if I'm stepping through all products. It seems inefficient to have 2 connections, readers, etc. for this. Is there a feature of ADO.NET DBs that I'm missing? How would you do it? Thanks!

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