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  • Python 2.6, 3 abstract base class misunderstanding

    - by Aaron
    I'm not seeing what I expect when I use ABCMeta and abstractmethod. This works fine in python3: from abc import ABCMeta, abstractmethod class Super(metaclass=ABCMeta): @abstractmethod def method(self): pass a = Super() TypeError: Can't instantiate abstract class Super ... And in 2.6: class Super(): __metaclass__ = ABCMeta @abstractmethod def method(self): pass a = Super() TypeError: Can't instantiate abstract class Super ... They both also work fine (I get the expected exception) if I derive Super from object, in addition to ABCMeta. They both "fail" (no exception raised) if I derive Super from list. I want an abstract base class to be a list but abstract, and concrete in sub classes. Am I doing it wrong, or should I not want this in python?

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  • Jquery Ajax Returned Array - how to handle in Javascript

    - by user232840
    Hi there, If someone could assist me please. I'm doing a jquery Ajax post, for some reason the Json object isn't working so just returning a php array instead $.post ( "classes/RegisterUser.php", $("#frmRegistration").serialize(), function(data) { alert(data); } ); The data is returned to Javascript 100% as array ( [key]=>value [Name] => SomeOneName [Surname] => SomeOneSurName ) How would i go about getting the value of Surname in Javascript? Thanks for your assistance? Regards

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  • [LINQ] Nested query problem

    - by code-zoop
    I have 3 classes in C#: classclass Folder { int Id { get; set; } List<File> files { get; set;} } class File { int Id { get; set; } Author author { get; set; } } class Author { int Id { get; set; } string Name { get; set; } } I have a list of Folder items (List): var folders = getAllFolders(); How can I use Linq to return a list of Folders from the list when i only know the Author id of the files? I need the list to contain all folders where a given Author has created a file! Thanks

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  • How does Hibernate detect dirty state of an entity object?

    - by ???'Lenik
    Is it using some kind of byte codes modification to the original classes? Or, maybe Hibernate get the dirty state by compare the given object with previously persisted version? I'm having a problem with hashCode() and equals() methods for complicated objects. I feel it would be very slow to compute hash code if the object has collection members, and cyclic references are also a problem. If Hibernate won't use hashCode()/equals() to check the dirty state, I guess I should not use equals()/hashCode() for the entity object (not value object), but I'm also afraid if the same operator (==) is not enough. So, the questions are: How does Hibernate know if a property of an object is changed? Do you suggest to override the hashCode()/equals() methods for complicated objects? What if they contains cyclic references? And, also, Would hashCode()/equals() with only the id field be enough?

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  • WPF style problem with custom control and textbox-derived class

    - by Martin
    I had the following situation: main application has app.xaml, which sets the style for TextBox controls a custom control is implemented in a separate DLL, and uses several TextBox controls The main application's TextBox style is applied to the custom control's TextBox controls. Cool! My problem comes in because I need to use a class derived from TextBox in the custom control. Now the main app's TextBox style is no longer applied. Can the custom control DLL have something like "app.xaml" where I can set the style for all my derived TextBox controls? Or can the main application somehow set the style for all TextBox-derived classes? Thanks!

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  • Using Gradle with an existing Android project

    - by Tom Reznik
    I have an existing Android project with the following structure: - ProjectName -- AndroidManifest.xml -- local.properties -- project.properties -- assets -- libs (containing all jars) -- modules (containing all library projects my project depends on) -- res -- src ---- com/namespace/projectname (all my classes including main activity are here) I haven't been using any specific build system to build my project other than the one provided by default with the Android Studio IDE (though the project was originally created with IntelliJ CE. I would like to use Gradle with the android plugin and do some work on my build process. I have tried several configurations in order to achieve this and have failed to complete a successful build every time. What's the recommended approach in this scenario? should I change my project structure? or is it possible to configure gradle using the existing structure? Any help would be greatly appreciated. Thanks!

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  • Reverse Expression.Like criterion

    - by Joel Potter
    How should I go about writing a backwards like statement using NHibernate criteria? WHERE 'somestring' LIKE [Property] + '%' Sub Question: Can you access the abstract root alias in a SQLCriterion expression? This is somewhat achievable using the SQLCriterion expression Expression.Sql("? like {alias}.[Property] + '.%'", value, NHibernateUtil.String); However, in the case of class inheritance, {alias} is replaced with the incorrect alias for the column. Example (these classes are stored in separate tables): public abstract class Parent { public virtual string Property { get; set; } } public class Child : Parent { } The above query executed with Child as the root type will replace {alias} with the alias to the Child table rather than the Parent table. This results in an invalid column exception. I need to execute a like statement as above where the property exists on the parent table rather than on the root type table.

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  • Best solution for language documentation.

    - by Simone Margaritelli
    I'm developing a new object oriented scripting language and the project itself is quite ready for audience now, so i'm starting to think about a serious (not as "drafty" as it is right now) way of document its grammar, functions from standard library and standard library classes. I've looked a bit around and almost every language hash its own web application for the documentation, Python uses Sphinx for instance. Which is the best PHP (don't have the time/will to install mod_who_knows_what on my server) application to accomplish this? I've used mediawiki a bit but i found its tag system a little bit hard to use in this context. Thanks for your answers.

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  • Are there any open source SimpleTest Test Cases that test PHP SPL interfaces

    - by JW
    I have quite a few objects in my system that implement the PHP SPL Iterator interface. As I write them I also write tests. I know that writing tests is generally NOT a cut 'n paste job. But, when it comes to testing classes that implement Standard PHP Library interfaces, surely it makes sense to have a few script snippets that can be borrowed and dropped in to a Test class - purely to test that particular interface. It seems sensible to have these publicly available. So, I was wondering if you knew of any?

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  • What to read as a good intro and quickstart to aspect-oriented programming and metaprogramming?

    - by Ivan
    As I've found myself repeating myself a lot, writing very similar queries and classes for different entities (despite of doing strong object and relational normalisation), etc, I've came to an Idea that I could and should automate the most of this and write an engine which will compile simple declarative models I specify into all the code limiting my job to describe the task and and finally just customise the result as needed. As far as I know this is about metaprogramming and aspect-oriented programming. How do I get acquainted with modern tools available quickly so that I don't invent one more bicycle developing my own?

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  • How can i use 'log' inside a src/groovy/ class

    - by firnnauriel
    I'm encountering this error: groovy.lang.MissingPropertyException: No such property: log for class: org.utils.MyClass Here's the content of the class: package org.utils class MyClass { int organizationCount = 0 public int getOrganizationCount(){ log.debug "There are ${organizationCount} organization(s) found." return organizationCount } } Do i need to add an import statement? What do i need to add? Note that the class is located in src/groovy/org/utils. I know that the 'log' variable is accessible in controllers, services, etc. Not sure in 'src' classes. Thanks.

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  • Django comments form validation, check if the comment is from authenticated user

    - by Headcrab
    I wanted to add reCaptcha to the comment form, but only for non-authenticated users. I've created my own comments app, using reCaptcha more or less according to this post, except that I don't have any (explicit) view function to post the comment, but instead I check captcha as a part of form validation process. Everything works fine so far. Now, how do I disable reCaptcha for a logged in user? Removing all reCaptcha-related fields in the template is no problem, but how do I validate the form, not checking captcha if the comment if from an authenticated user? Alternatively, is there a way to use two different comment form classes, depending on whether the user is authenticated or not?

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  • Transactions in hibernate

    - by kumar1425
    Hi I new to hibernate In my project, i need to handle transactions. How to handle declarative transactions with in two classes Examples: //class 1 class A{ createA() { insert(A); } } //class 2 class B { createB() { insert(B); } } //class 3 @Transaction(Exception.class) class C { test() { create(A); create(B); } } As per the above code is there any possibility to handle transactions, in such a way that if the insert in classA success and the insert in the classB fails then the transaction should rollback and remove the record inserted in the table A corresponding to the Class A please help me with this using declarative transactions.... Thanks in adavace....

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  • Data Access Layer in ASP.Net: Where do I create the Connection?

    - by atticae
    If I want to create a 3-Layer ASP.Net application (Presentation Layer, Business Layer, Data Access Layer), where is the best place to create the Connection objects? So far I used a helper class in my Presentation Layer to create an IDbCommand from the ConnectionString in the web.config on each page and passed it on to the DAL classes/methods. Now I am not so sure, if this part shouldn't also be included in the DAL somehow, because it obviously is part of the Data Access. The DAL is in a separately compilated project, so I dont have access to the web.config and cannot access the connection string (right?). What is the best practice here?

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  • tools for testing vim plugins

    - by intuited
    I'm looking for some tools for testing vim scripts. Either vim scripts that do unit/functional testing, or classes for some other library (eg Python's unittest module) that make it convenient to run vim with parameters that cause it to do some tests on its environment, and determine from the output whether or not a given test passed. I'm aware of a couple of vim scripts that do unit testing, but they're sort of vaguely documented and may or may not actually be useful: vim-unit: purports "To provide vim scripts with a simple unit testing framework and tools" first and only version (v0.1) was released in 2004 documentation doesn't mention whether or not it works reliably, other than to state that it is "fare [sic] from finished". unit-test.vim: This one also seems pretty experimental, and may not be particularly reliable. May have been abandoned or back-shelved: last commit was in 2009-11 ( 6 months ago) No tagged revisions have been created (ie no releases) So information from people who are using one of those two existent modules, and/or links to other, more clearly usable, options, are very welcome.

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  • Refactoring tools for namespaces and physical project structure

    - by simendsjo
    When I hack around, some code tend to get much bigger than originally planned. As this happens I usually introduce/collapse/merge namespaces, move files between them, move folders etc etc. Sometimes, if I don't have a clear picture of the end result, this is a real pain and really easy to just "skip". This leads the project deteriorate where classes belong elsewhere, strange namespaces, no folders/wrong folders etc. And then I usually cannot take it anymore and do a larger cleanup - which is usually not difficult, just very tedious and it feels nice to do everything at once, so I do a code freeze while finishing up. So my question is... Are there any tools to help refactoring the namespace/physical aspects of a project?

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  • How does a custom accessor method implementation in Core Data look like?

    - by dontWatchMyProfile
    The documentation is pretty confusing on this one: The implementation of accessor methods you write for subclasses of NSManagedObject is typically different from those you write for other classes. If you do not provide custom instance variables, you retrieve property values from and save values into the internal store using primitive accessor methods. You must ensure that you invoke the relevant access and change notification methods (willAccessValueForKey:, didAccessValueForKey:, willChangeValueForKey:, didChangeValueForKey:, willChangeValueForKey:withSetMutation:usingObjects:, and didChangeValueForKey:withSetMutation:usingObjects:). NSManagedObject disables automatic key-value observing (KVO, see Key-Value Observing Programming Guide) change notifications, and the primitive accessor methods do not invoke the access and change notification methods. In accessor methods for properties that are not defined in the entity model, you can either enable automatic change notifications or invoke the appropriate change notification methods. Are there any examples that show how these look like?

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  • Django adminsite customize search_fields query

    - by dArignac
    Howdy! In the django admin you can set the search_fields for the ModelAdmin to be able to search over the properties given there. My model class has a property that is not a real model property, means it is not within the database table. The property relates to another database table that is not tied to the current model through relations. But I want to be able to search over it, so I have to somehow customize the query the admin site creates to do the filtering when the search field was filled - is this possible and if, how? I can query the database table of my custom property and it then returns the ids of the model classes fitting the search. This then, as I said, has to flow into the admin site search query. Thanks!

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  • Should I use implicit conversions to enforce preconditions?

    - by Malvolio
    It occurs to me that I could use use implicit conversions to both announce and enforce preconditions. Consider this: object NonNegativeDouble { implicit def int2nnd(d : Double) : NonNegativeDouble = new NonNegativeDouble(d) implicit def nnd2int(d : NonNegativeDouble) : Double = d.v def sqrt(n : NonNegativeDouble) : NonNegativeDouble = scala.math.sqrt(n) } class NonNegativeDouble(val v : Double ) { if (v < 0) { throw new IllegalArgumentException("negative value") } } object Test { def t1 = { val d : Double = NonNegativeDouble.sqrt(3.0); printf("%f\n", d); val n : Double = NonNegativeDouble.sqrt(-3.0); } } Ignore for the moment the actual vacuity of the example: my point is, the subclass NonNegativeDouble expresses the notion that a function only takes a subset of the entire range of the class's values. First is this: A good idea, a bad idea, or an obvious idea everybody else already knows about Second, this would be most useful with basic types, like Int and String. Those classes are final, of course, so is there a good way to not only use the restricted type in functions (that's what the second implicit is for) but also delegate to all methods on the underlying value (short of hand-implementing every delegation)?

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  • Using Property Builtin with GAE Datastore's Model

    - by ejel
    I want to make attributes of GAE Model properties. The reason is for cases like to turn the value into uppercase before storing it. For a plain Python class, I would do something like: Foo(db.Model): def get_attr(self): return self.something def set_attr(self, value): self.something = value.upper() if value != None else None attr = property(get_attr, set_attr) However, GAE Datastore have their own concept of Property class, I looked into the documentation and it seems that I could override get_value_for_datastore(model_instance) to achieve my goal. Nevertheless, I don't know what model_instance is and how to extract the corresponding field from it. Is overriding GAE Property classes the right way to provides getter/setter-like functionality? If so, how to do it? Added: One potential issue of overriding get_value_for_datastore that I think of is it might not get called before the object was put into datastore. Hence getting the attribute before storing the object would yield an incorrect value.

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  • Is it bad practice to use python's getattr extensively?

    - by Wilduck
    I'm creating a shell-like environment. My original method of handleing user input was to use a dictionary mapping commands (strings) to methods of various classes, making use of the fact that functions are first class objects in python. For flexibility's sake (mostly for parsing commands), I'm thinking of changing my setup such that I'm using getattr(command), to grab the method I need and then passing arguments to it at the end of my parser. Another advantage of this approach is not having to update my (currently statically implemented) command dictionary every time I add a new method/command. My question is, will I be taking a hit to the efficiency of my shell? Does it matter how many methods/commands I have? I'm currently looking at 30 some commands, which could eventually double.

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  • Do I still have to implement a singleton class by hand in .net, even when using .Net4.0?

    - by Hamish Grubijan
    Once the singleton pattern is understood, writing subsequent singleton classes in C# is a brainless exercise. I would hope that the framework would help you by providing an interface or a base class to do that. Here is how I envision it: public sealed class Schablone : ISingleton<Schablone> { // Stuff forced by the interface goes here // Extra logic goes here } Does what I am looking for exist? Is there some syntactic sugar for constructing a singleton class - whether with an interface, a class attribute, etc.? Can one write a useful and bullet-proof ISingleton themselves? Care to try? Thanks!

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  • Call a function from another Class - Obj C

    - by AndrewDK
    I'm trying to figure out how I can call a function from another one of my classes. I'm using a RootViewController to setup one of my views as lets say AnotherViewController So in my AnotherViewController im going to add in on the .h file @class RootViewController And in the .m file im going to import the View #import "RootViewController.h" I have a function called: -(void)toggleView { //do something } And then in my AnotherViewController I have a button assigned out as: -(void)buttonAction { //} In the buttonAction I would like to be able to call the function toggleView in my RootViewController. Can someone clarify on how I do this. I've tried adding this is my buttonAction: RootViewController * returnRootObject = [[RootViewController alloc] init]; [returnRootObject toggleView]; But I dont think that's right. Thanks in advanced.

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  • Ruby on Rails: Unit Testing non activerecord models and still load fixtures

    - by Vaibhav Gumashta
    I may be missing something but I am stuck in this scenario: I have a non activerecord model, which I want to test. I have derived its test case class from: Test::Unit::TestCase. However, the test case class for the model, uses within itself, other activerecord model classes and I want to load fixtures for them. My problem is that the fixtures class method is available only when I subclass the test case class from ActiveSupport::TestCase (it is defined within ActiveRecord::TestFixtures which gets included in ActiveSupport::TestCase). Any help, coz running the tests gives me the error: undefined method "fixtures" (which is understandable) and in case I derive my test case class from ActiveSupport::TestCase it complains that there is no corresponding DB table. Also, I don't want to create a dummy table for backing my model class. Thanks a ton!

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  • Why doesn't ConcurrentQueue<T>.Count return 0 when IsEmpty == true?

    - by DanTup - Danny Tuppeny
    I was reading about the new concurrent collection classes in .NET 4 on James Michael Hare's blog, and the page talking about ConcurrentQueue<T> says: It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. I'm curious - if there is a reason to use IsEmpty instead of comparing Count to 0, why does the class not internally check IsEmpty and return 0 before doing any of the expensive work to count? E.g.: public int Count { get { // Check IsEmpty so we can bail out quicker if (this.IsEmpty) return 0; // Rest of "expensive" counting code } } It seems strange to suggest this if it could be "fixed" so easily with no side-effects?

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