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  • Normalise this Table?

    - by Abs
    Hello all, I am creating a social bookmarking app. I am having a re-thought of the DB design in the middle of development. Should I normalise the bookmarks table and remove the tag columns that I have into a separate table. I have 10 tags per bookmark and therefore 10 columns per record (per bookmark). It seems to me that breaking the table into two would just mean I would have to do a join but the way I currently have it, its a straight select - but the table doesn't feel right...? Thanks all

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  • Do ORMs normally allow circular relations? If so, how would they handle it?

    - by SeanJA
    I was hacking around trying to make a basic orm that has support for the one => one and one => many relationships. I think I succeeded somewhat, but I am curious about how to handle circular relationships. Say you had something like this: user::hasOne('car'); car::hasMany('wheels'); car::property('type'); wheel::hasOne('car'); You could then do this (theoretically): $u = new user(); echo $u->car->wheels[0]->car->wheels[1]->car->wheels[2]->car->wheels[3]->type; #=> "monster truck" Now, I am not sure why you would want to do this. It seems like it wastes a whole pile of memory and time just to get to something that could have been done in a much shorter way. In my small ORM, I now have 4 copies of the wheel class, and 4 copies of the car class in memory, which causes a problem if I update one of them and save it back to the database, the rest get out of date, and could overwrite the changes that were already made. How do other ORMs handle circular references? Do they even allow it? Do they go back up the tree and create a pointer to one of the parents? DO they let the coder shoot themselves in the foot if they are silly enough to go around in circles?

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  • Accessing a JavaScript object property names with a "-" in it

    - by Anil kumar
    I have a requirement to read JSON data in my application. Problem is that the JSON data that I am getting from the service includes "-" and when I am trying to read it, I am getting "Uncaught ReferenceError: person is not defined ". e.g. I have below JSON object- var JSONObject ={ "name-person":"John Johnson", "street":"Oslo West 16", "age":33, "phone":"555 1234567"}; when I am writing below console log statement I am getting "Uncaught ReferenceError: person is not defined " error console.log(JSONObject.name-person); Can someone please help me how to read such data which includes "-" in it? I do not have control on the service and the DB so to modify source data is not in my hand.

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  • algorithm to find Best 8 minute window in a 1 hour run

    - by Arun
    I have a requirement like, an activity runs for about more than an hour. I need to get the best 8 minute window where some parameters are maximum. say a value x, which is dynamic for every second. if my activity runs for one hr,i get 3600 values for x. I need to find the best continuous 8 minute time interval where x value was the highest among all the others. if i capture say from 0th minute to 8th minute, there may be another time frame like 0.4 to 8.4 where it was maximum. the granularity is one second. every second we need to consider. basically the peak 8 minute window where x was maximum. please help me with the design

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  • Help with prototype object

    - by nemiss
    Hi, I am mlearning javascript and have some trouble creating an onject via prototype. I have this: <script type="text/javascript"> function myclass(a, b, c) { if (arguments.length) { this.Init(a, b, c); } } myclass.prototype.Init = function(a, b, c) { this.param1 = a; this.param2 = b; this.param3 = c; }; myclass.prototype.Print = function() { alert(this.param1 + '-' + this.param2 + '-' + this.param3); }; var myObject = myclass(3, 5, 6); myObject.Print(); </script> but I get an error on line with this.Init(a, b, c); Error: Object doesn't support this property or method

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  • Release an object without a pointer?

    - by Kai Friis
    I’ve just started developing for iPhone and am trying to get my head around memory management. I made a small program that shows a map and an annotation on the map. For the annotation I made a simple class that implements the MKAnnotation protocol. To create and add the annotation I wrote this: [self.myMapView addAnnotation:[[MyAnnotation alloc] init]]; It worked fine until I tried to release the object. Nothing to release. This is what I would have done in C#, I guess it doesn’t work without garbage collection? So is this the only way to do it? MyAnnotation *myAnnotation = [[MyAnnotation alloc] init]; [self.myMapView addAnnotation: myAnnotation]; [myAnnotation release];

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  • How can I define an empty array in a Perl construtor?

    - by Laimoncijus
    I am just beginner with Perl, so if it sounds stupid - sorry for that :) My problem is - I am trying to write a class, which has an empty array, defined in constructor of a class. So I am doing this like this: package MyClass; use strict; sub new { my ($C) = @_; my $self = { items => () }; bless $self, ref $C || $C; } sub get { return $_[0]->{items}; } 1; Later I am testing my class with simple script: use strict; use Data::Dumper; use MyClass; my $o = MyClass->new(); my @items = $o->get(); print "length = ", scalar(@items), "\n", Dumper(@items); And while running the script I get following: $ perl my_test.pl length = 1 $VAR1 = undef; Why am I doing wrong what causes that I get my items array filled with undef? Maybe someone could show me example how the class would need to be defined so I would not get any default values in my array?

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  • How to set xmlns when serializing object in c#

    - by John
    I am serializing an object in my ASP.net MVC program to an xml string like this; StringWriter sw = new StringWriter(); XmlSerializer s = new XmlSerializer(typeof(mytype)); s.Serialize(sw, myData); Now this give me this as the first 2 lines; <?xml version="1.0" encoding="utf-16"?> <GetCustomerName xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> my question is, How can I change the xmlns and the encoding type, when serializing? Thanks

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  • domain modeling naming problem

    - by cherouvim
    Hello There are some simple entities in an application (e.g containing only id and title) which rarely change and are being referenced by the more complex entities of the application. These are usually entities such as Country, City, Language etc. How are these called? I've used the following names for those in the past but I'm not sure which is the best way to call them: reference data lookup values dictionaries thanks

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  • Custom class object in Initialization list

    - by Michael
    I have a class Bar: class Bar { public: Bar(void); ~Bar(void); }; And a class Foo that gets a reference to Bar object as a constructor parameter and needs to save it in a private member bar_ : class Foo { private: Bar& bar_; public: Foo(Bar& bar) : bar_(bar) {} ~Foo(void) {} }; This doesn't compile : overloaded member function not found in 'Parser' missing type specifier - int assumed. Note: C++ does not support default-int Now i suspect couple of things that i need to assure, the second error is for Bar& bar_; declaration in Foo. Do i need to use an explicit constructor when declaring bar_ ? I am interested in learning how the compiler works regarding this matter, so a detailed explanation would be highly appreciated. Thanks.

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  • Django paging object has issues with Postgresql QuerySets

    - by pivotal
    I have some django code that runs fine on a SQLite database or on a MySQL database, but it runs into problems with Postgres, and it's making me crazy that no one has has this issue before. I think it may also be related to the way querysets are evaluated by the pager. In a view I have: def index(request, page=1): latest_posts = Post.objects.all().order_by('-pub_date') paginator = Paginator(latest_posts, 5) try: posts = paginator.page(page) except (EmptyPage, InvalidPage): posts = paginator.page(paginator.num_pages) return render_to_response('blog/index.html', {'posts' : posts}) And inside the template: {% for post in posts.object_list %} {# some rendering jazz #} {% endfor %} This works fine with SQLite, but Postgres gives me: Caught TypeError while rendering: 'NoneType' object is not callable To further complicate things, when I switch the Queryset call to: latest_posts = Post.objects.all() Everything works great. I've tried re-reading the documentation, but found nothing, although I admit I'm a bit clouded by frustration at this point. What am I missing? Thanks in advance.

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  • To Interface or Not?: Creating a polymorphic model relationship in Ruby on Rails dynamically..

    - by Globalkeith
    Please bear with me for a moment as I try to explain exactly what I would like to achieve. In my Ruby on Rails application I have a model called Page. It represents a web page. I would like to enable the user to arbitrarily attach components to the page. Some examples of "components" would be Picture, PictureCollection, Video, VideoCollection, Background, Audio, Form, Comments. Currently I have a direct relationship between Page and Picture like this: class Page < ActiveRecord::Base has_many :pictures, :as => :imageable, :dependent => :destroy end class Picture < ActiveRecord::Base belongs_to :imageable, :polymorphic => true end This relationship enables the user to associate an arbitrary number of Pictures to the page. Now if I want to provide multiple collections i would need an additional model: class PictureCollection < ActiveRecord::Base belongs_to :collectionable, :polymorphic => true has_many :pictures, :as => :imageable, :dependent => :destroy end And alter Page to reference the new model: class Page < ActiveRecord::Base has_many :picture_collections, :as => :collectionable, :dependent => :destroy end Now it would be possible for the user to add any number of image collections to the page. However this is still very static in term of the :picture_collections reference in the Page model. If I add another "component", for example :video_collections, I would need to declare another reference in page for that component type. So my question is this: Do I need to add a new reference for each component type, or is there some other way? In Actionscript/Java I would declare an interface Component and make all components implement that interface, then I could just have a single attribute :components which contains all of the dynamically associated model objects. This is Rails, and I'm sure there is a great way to achieve this, but its a tricky one to Google. Perhaps you good people have some wise suggestions. Thanks in advance for taking the time to read and answer this.

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  • yet another confusion with multiprocessing error, 'module' object has no attribute 'f'

    - by gatoatigrado
    I know this has been answered before, but it seems that executing the script directly "python filename.py" does not work. I have Python 2.6.2 on SuSE Linux. Code: #!/usr/bin/python # -*- coding: utf-8 -*- from multiprocessing import Pool p = Pool(1) def f(x): return x*x p.map(f, [1, 2, 3]) Command line: > python example.py Process PoolWorker-1: Traceback (most recent call last): File "/usr/lib/python2.6/multiprocessing/process.py", line 231, in _bootstrap self.run() File "/usr/lib/python2.6/multiprocessing/process.py", line 88, in run self._target(*self._args, **self._kwargs) File "/usr/lib/python2.6/multiprocessing/pool.py", line 57, in worker task = get() File "/usr/lib/python2.6/multiprocessing/queues.py", line 339, in get return recv() AttributeError: 'module' object has no attribute 'f'

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  • Events in Classes (VB.NET)

    - by Otaku
    I find that I write a lot of code within my classes to keep properties in sync with each other. I've read about Events in Classes, but have not been able to wrap my head around how to make them work for what I'm looking for. I could use some advice here. For example, in this one I always want to keep myColor up to date with any change whatsoever in any or all of the Red, Green or Blue properties. Class myColors Private Property Red As Byte Private Property Green As Byte Private Property Blue As Byte Private Property myColor As Color Sub New() myColor = Color.FromArgb(0, 0, 0) End Sub Sub ChangeRed(ByVal r As Byte) Red = r myColor = Color.FromArgb(Red, Green, Blue) End Sub Sub ChangeBlue(ByVal b As Byte) Blue = b myColor = Color.FromArgb(Red, Green, Blue) End Sub End Class If one or more of those changes, I want myColor to be updated. Easy enough as above, but is there a way to work with events that would automatically do this so I don't have to put myColor = Color.FromArgb(Red, Green, Blue) in every sub routine?

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  • Entity Framework 4 missing features?

    - by Roger Alsing
    I'm well aware that similair topics have been brought up before e.g. http://stackoverflow.com/questions/1639043/entity-framework-4-vs-nhibernate But instead of arguments like: NHibernate have been around longer and is more mature EF4 is drag n drop and not enterprisy EF4 and LinqToSql are ... I would like to see a more detailed list of features that you consider missing from EF4. Personally, I think the lack of enum support is the biggest drawback of EF4.

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  • jquery split() and indexOf results in "Object doesn't support this property or method"

    - by chris
    I have the following code: var selected = $('#hiddenField').val().split(","); ... if (selected.indexOf(id) > 0) { ... set value ... } I'm dynamically creating a CheckBoxList, and trying to remember the state of the checkboxes by putting the selected IDs into the hidden field. I get an error stating that "Object doesn't support this property or method". My assumption is that selected is an array, which should support indexOf. Is that incorrect?

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  • jQuery object are immutable?

    - by Daniel
    Hello a new noob on jQuery here and I was wondering if jQuery objects are immutable. For example: var obj1 = $("<tag></tag>"); var obj2 = obj1.append("something"); Will obj1 and obj2 be the same meaning obj2 will reference obj1? UPDATE: The above example kind of scratches the surface of what i want to know, a more accurate question is : If i chain function from the jQuery api will they return the same object or a new one (as the case with strings in Java)?

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  • Strange Error - "Object moved to here."

    - by Dkong
    I get the strange error "Object moved to here." on a blank white page when I try to login on a site I created. It works fine locally but not when I deploy it to the test or production server. I am not doing anything odd, just using basic authentication code in a helper function as follows... public static bool AuthenticateUser(string Username, string Password, bool PersistLogin, string RedirectionURL) { if (Membership.ValidateUser(Username, Password)) { FormsAuthentication.SetAuthCookie(Username, PersistLogin); HttpContext.Current.Response.Redirect(RedirectionURL,true); return true; } else return false; }

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  • C# Running several tasks at different intervals

    - by Nir
    A design question: I'd like to build a Windows service that executes different commands at different intervals. For simplicity's sake, let's say I want to run some batch files. The input it gets is a list of files and the intervals at which to execute. For example: a.bat - 4 minutes b.bat - 1 minute c.bat - 1 minute d.bat - 2 minutes I was thinking about sorting them according to intervals, and then setting a timer for each of the intervals. I'm not sure this is the best solution and I'd be happy to hear some feedbacks. Thanks!

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  • How to use a servlet to repsond to a request for an object

    - by Rick
    I'm sure this is easy, but I don't work with website development very often and I'm lost on this one. I have a web application that needs to support multiple clients with different settings, icons and other content. The contents of these files are in separate directories for each client. What I would like to do is respond to a request sent to a jsp/java servlet. The servlet will look up the proper folder location in a database (I have the database stuff working) and send the actual object to the requesting page whether it is xml, graphic or video. How do I do that? What methods should I be using. Help I'm lost! :(

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  • Initial capacity of collection types, i.e. Dictionary, List

    - by Neil N
    Certain collection types in .Net have an optional "Initial Capacity" constructor param. i.e. Dictionary<string, string> something = new Dictionary<string,string>(20); List<string> anything = new List<string>(50); I can't seem to find what the default initial capacity is for these objects on MSDN. If I know I will only be storing 12 or so items in a dictionary, doesn't it make sense to set the initial capacity to something like 20? My reasoning is, assuming the capacity grows like it does for a StringBuiler, which doubles each time the capacity is hit, and each re-allocation is costly, why not pre-set the size to something you know will hold your data, with some extra room just in case? If the initial capacity is 100, and I know I will only need a dozen or so, it seems as though the rest of that allocated RAM is allocated for nothing. Please spare me the "premature optimization" speil for the O(n^n)th time. I know it won't make my apps any faster or save any meaningful amount of memory, this is mostly out of curiosity.

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  • How should I declare default values for instance variables in Python?

    - by int3
    Should I give my class members default values like this: class Foo: num = 1 or like this? class Foo: def __init__(self): self.num = 1 In this question I discovered that in both cases, bar = Foo() bar.num += 1 is a well-defined operation. I understand that the first method will give me a class variable while the second one will not. However, if I do not require a class variable, but only need to set a default value for my instance variables, are both methods equally good? Or one of them more 'pythonic' than the other? One thing I've noticed is that in the Django tutorial, they use the second method to declare Models. Personally I think the second method is more elegant, but I'd like to know what the 'standard' way is.

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  • C#: why have all static methods/variables in a non-static class?

    - by Craig Johnston
    I have come across a class which is non-static, but all the methods and variables are static. Eg: public class Class1 { private static string String1 = "one"; private static string String2 = "two"; public static void PrintStrings(string str1, string str2) { ... All the variables are static across all instances, so there is no point having separate instances of the class. Is there any reason to create a class such as this?

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  • Partial class or "chained inheritance"

    - by Charlie boy
    Hi From my understanding partial classes are a bit frowned upon by professional developers, but I've come over a bit of an issue; I have made an implementation of the RichTextBox control that uses user32.dll calls for faster editing of large texts. That results in quite a bit of code. Then I added spellchecking capabilities to the control, this was made in another class inheriting RichTextBox control as well. That also makes up a bit of code. These two functionalities are quite separate but I would like them to be merged so that I can drop one control on my form that has both fast editing capabilities and spellchecking built in. I feel that simply adding the code form one class to the other would result in a too large code file, especially since there are two very distinct areas of functionality, so I seem to need another approach. Now to my question; To merge these two classes should I make the spellchecking RichTextBox inherit from the fast edit one, that in turn inherits RichTextBox? Or should I make the two classes partials of a single class and thus making them more “equal” so to speak? This is more of a question of OO principles and exercise on my part than me trying to reinvent the wheel, I know there are plenty of good text editing controls out there. But this is just a hobby for me and I just want to know how this kind of solution would be managed by a professional. Thanks!

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