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  • php Set a anonymous function in an instance

    - by geekay
    I am just starting out with PHP, and I am wondering if there is a way to add an anonymous function to a class instance. For instance, lets say... class A{ public B; } $c = new A(); //This is where I am getting a little confused... //The following wont work $c->B = function(){echo('HelloWorld');}; $c->B(); What I am hoping to do is reuse the same spit of code in a great number of different applications, and make it so that I can just 'swap-out' and replace functions in specific instances. I am using php5.3 (so anonymous functions should work, just not in the way that I am using them). Thanks so very much for your time!! -GK

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  • code style for private methods in c#

    - by illdev
    I just found out, that it seems a common pattern to user UpperFirstLetterPascalCase() for private methods. I for myself, find this completely inconsistent with naming rules of private instance fields and variables and I find it difficult to read/debug, too. I would want to ask, why using a first upper letter for methods could be a better choice than a first lower (doThis())? Just out of curiosity...

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  • Why are my ActiveRecord class instance variables disappearing after the first request in development

    - by Paul C
    I have a class instance variable on one of my AR classes. I set its value at boot with an initializer and, after that, never touch it again except to read from it. In development mode, this value disappears after the first request to the web server. However, when running tests, using the console or running the production server this does not happen. # The AR class class Group < ActiveRecord::Base class << self attr_accessor :path end end # The initializer Group.path = File.join(RAILS_ROOT, "public", "etc") # First request in a view %p= Group.path #=> "/home/rails/app/public/etc" # Second request in a view %p= Group.path #=> nil Is there something about development mode that nukes instance variables from classes with each request? If so, is there a way to disable this for specific variables or classes?

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  • Java: when to use static methods

    - by KP65
    Hello, I am wondering when to use static methods? Say If i have a class with a few getters and setters, a method or two, and i want those methods only to be invokable on an instance object of the class. Does this mean i should use a static method? e.g Obj x = new Obj(); x.someMethod or Obj.someMethod (is this the static way?) I'm rather confused!

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  • Understanding the singleton class when aliasing a instance method

    - by Backo
    I am using Ruby 1.9.2 and the Ruby on Rails v3.2.2 gem. I am trying to learn Metaprogramming "the right way" and at this time I am aliasing an instance method in the included do ... end block provided by the RoR ActiveSupport::Concern module: module MyModule extend ActiveSupport::Concern included do # Builds the instance method name. my_method_name = build_method_name.to_sym # => :my_method # Defines the :my_method instance method in the including class of MyModule. define_singleton_method(my_method_name) do |*args| # ... end # Aliases the :my_method instance method in the including class of MyModule. singleton_class = class << self; self end singleton_class.send(:alias_method, :my_new_method, my_method_name) end end "Newbiely" speaking, with a search on the Web I came up with the singleton_class = class << self; self end statement and I used that (instead of the class << self ... end block) in order to scope the my_method_name variable, making the aliasing generated dynamically. I would like to understand exactly why and how the singleton_class works in the above code and if there is a better way (maybe, a more maintainable and performant one) to implement the same (aliasing, defining the singleton method and so on), but "the right way" since I think it isn't so.

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  • Methods in Ruby: objects or not?

    - by Mladen Jablanovic
    Inspired by this discussion, after some googling I wasn't able to find an answer to a pretty simple question regarding methods in Ruby: are they objects or not? There are different opinions here and there, and I would really like to hear, let's say, an in-depth explanation. I'm aware of Object#method method, which takes a method name and returns a Method instance, but, on the other hand, there's a similar thing you can do with blocks to make them into Proc instances, and blocks aren't objects, so what makes methods any different?

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  • Cannot access Class methods from previous windows form - C#

    - by George
    I am writing an app, still, where I need to test some devices every minute for 30 minutes. It made sense to use a timer set to kick off every 60 secs and do whats required in the event handler. However, I need the app to wait for the 30 mins until I have finished with the timer since the following code alters the state of the devices I am trying to monitor. I obviously don't want to use any form of loop to do this. I thought of using another windows form, since I also display the progress, which will simply kick off the timer and wait until its complete. The problem I am having with this is that I use a device Class and cant seem to get access to the methods in the device class from the 2nd (3rd actually - see below) windows form. I have an initial windows form where I get input from the user, then call the 2nd windows form where it work out which tests need to be done and which device classes need to be used, and then I want to call the 3rd windows form to handle the timer. I will have up to 6-7 device classes and so wanted to only instantiate them when actually requiring them, from the 2nd form. Should I have put this logic into the 1st windows form (program class ??) ? Would I not still have the problem of not being able to access device class methods from there too ? Anyway, perhaps someone knows of a better way to do the checks every minute without the rest of the code executing (and changing the status of the devices) or how I should be accessing the methods in the app ?? Well that's the problem, I cant get that part of it to work correctly. Here is the definition for the calling form including the device class - namespace NdtStart { public partial class fclsNDTCalib : Form { NDTClass NDT = new NDTClass(); public fclsNDTCalib() (new fclsNDTTicker(NDT)).ShowDialog(); Here is the class def for the called form - namespace NdtStart { public partial class fclsNDTTicker : Form { public fclsNDTTicker() I tried lots but couldn't get the arguments to work.

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  • Is there a way to use Linq projections with extension methods

    - by Acoustic
    I'm trying to use AutoMapper and a repository pattern along with a fluent interface, and running into difficulty with the Linq projection. For what it's worth, this code works fine when simply using in-memory objects. When using a database provider, however, it breaks when constructing the query graph. I've tried both SubSonic and Linq to SQL with the same result. Thanks for your ideas. Here's an extension method used in all scenarios - It's the source of the problem since everything works fine without using extension methods public static IQueryable<MyUser> ByName(this IQueryable<MyUser> users, string firstName) { return from u in users where u.FirstName == firstName select u; } Here's the in-memory code that works fine var userlist = new List<User> {new User{FirstName = "Test", LastName = "User"}}; Mapper.CreateMap<User, MyUser>(); var result = (from u in userlist select Mapper.Map<User, MyUser>(u)) .AsQueryable() .ByName("Test"); foreach (var x in result) { Console.WriteLine(x.FirstName); } Here's the same thing using a SubSonic (or Linq to SQL or whatever) that fails. This is what I'd like to make work somehow with extension methods... Mapper.CreateMap<User, MyUser>(); var result = from u in new DataClasses1DataContext().Users select Mapper.Map<User, MyUser>(u); var final = result.ByName("Test"); foreach(var x in final) // Fails here when the query graph built. { Console.WriteLine(x.FirstName); } The goal here is to avoid having to manually map the generated "User" object to the "MyUser" domain object- in other words, I'm trying to find a way to use AutoMapper so I don't have this kind of mapping code everywhere a database read operation is needed: var result = from u in new DataClasses1DataContext().Users select new MyUser // Can this be avoided with AutoMapper AND extension methods? { FirstName = v.FirstName, LastName = v.LastName };

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  • Docs for auto-generated methods in Ruby on Rails

    - by macek
    Rails has all sorts of auto-generated methods that I've often times struggled to find documentation for. For example, in routes.rb, if I have: map.resources :projects do |p| p.resources :tasks end This will get a plethora of auto-generate path and url helpers. Where can I find documentation for how to work with these paths? I generally understand how to work with them, but more explicit docs might help me understand some of the magic that happens behind the scenes. # compare project_path(@project) project_task_path(@project, @task) # to project_path(:id => @project.id) project_task_path(:project_id => @project.id, :id => @task.id) Also, when I change an attribute on a model, @post.foo_changed? will be true. Where can I find documentation for this and all other magical methods that are created like this? If the magic is there, I'd love to take advantage of it. And finally: Is there a complete resource for config.___ statements for environment.rb? I was able to find docs for Configuration#gem but what attributes can I set within the stubs like config.active_record.___, config.action_mailer.___, config.action_controller.___, etc. Again, I'm looking for a complete resource here, not just a settings for the examples I provided. Even if you can only answer one of these questions, please chime in. These things seem to have been hiding from me and it's my goal to get them some more exposure, so I'll be upvoting all links to docs that point me to what I'm looking for. Thanks! ps, If they're not called auto-generated methods, I apologize. Someone can teach me a lesson here, too :) Edit I'm not looking for tutorials here, folks. I have a fair amount of experience with rails; I'm just looking for complete docs. E.g., I understand how routing works, I just want docs where I can read about all of the usage options.

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  • Business entity: private instance VS single instance

    - by taoufik
    Suppose my WinForms application has a business entity Order, the entity is used in multiple views, each view handles a different domain or use-case in the application. As an example, one managing orders, the other one digging into one order and displaying additional data. If I'd use nHibernate (or any other ORM) and use one session/dataContext per view (or per db action), I'd end up getting two different instances for the same Order (let's say orderId = 1). Although functionally the same entity, they are technically two different instances. Yes, I could implement Equals/GetHashcode to make them "seem" the same. Why would you go for a single instance per entity vs private instances per view or per use-case? Having single instances has the advantage of sharing INotifyPropertyChanged events, and sharing additional (non-persistent) data. Having a private instance in each view would give you the flexibility of the undo functionality on a view level. In the example above, I'd allow the user to change order details, and give them the flexibility to not save the change. Here, synchronisation between the view/use-case happens on a data persistence level. What would your argument be?

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  • Add a child inside a newly created instance, inside of a loop in AS3

    - by HeroicNate
    I am trying to create a gallery where each thumb is housed inside of it's own movie clip that will have more data, but it keeps failing because it won't let me refer to the newly created instance of the movie clip. Below is what I am trying to do. var xml:XML; var xmlReq:URLRequest = new URLRequest("xml.xml"); var xmlLoader:URLLoader = new URLLoader(); var imageLoader:Loader; var vidThumbn:ThumbNail; var next_y:Number = 0; for(var i:int = 0; i < xml.downloads.videos.video.length(); i++) { vidThumbn = new ThumbNail(); imageLoader = new Loader(); imageLoader.load(new URLRequest(xml.downloads.videos.video[i].ThumbnailImage)); vidThumbn.y = next_y; vidThumbn.x = 0; next_y += 117; imageLoader.name = xml.downloads.videos.video[i].Files[0].File.URL; videoBox.thumbList.thumbListHolder.addChild(vidThumbn); videoBox.thumbList.thumbListHolder.vidThumbn.addChild(imageLoader); } It dies every time on that last line. How do I refer to that vidThumbn instance so I can add the imageLoader? I don't know what I'm missing. It feels like it should work.

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  • how can I get instance from the property.

    - by viky
    In my application I have a class which has properties of user-defined types like this: class MyType { public A MyProperty { get; set; } } class A { .....some methods and proeprties } for some operations that I need to perform from my main program, I create a List of MyProperty whenever creating object of MyType and pass it to my main program and there I perform different operation on these properties which reflects in there instances also. Is there any way by which I could get the object instance for any particular MyProperty from that property in the list.

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  • MEF instance management

    - by Lawrence A. Contreras
    I am working on application that has multiple modules and sub modules. Here's what I need to do: ModuleA has a sub module SubModuleA, SubModuleB, SubModuleC. I want to export ModuleA, SubModuleA, SubModuleB, SubModuleC. ModuleA can have multiple instances. Whenever I import ModuleA inside the sub modules, I want to get the correct instance and also when I import SubModuleA,SubModuleB and SubModuleC inside other classes. How can I manage that scenario using MEF? Do I really need to use MEF. Updated: Here's a quick example: public class School { List<Classroom> classRooms { get; set; } } [Export] public class Classroom { List<Teacher> teachers { get; set; } } public class Teacher { List<Student> students { get; set; } } public class Student { [Import] Classroom classroom { get; set; } } As you can see, I want to export the classroom class because I need to import it in the Student class, let's just say that I really need the classroom class inside the student class. I want to skip the part where we pass the classroom to the teacher and from the teacher we'll pass it to the student. But when I import classroom, I want to have the correct instance where that class room contains the teacher of the student.

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  • Visitor and templated virtual methods

    - by Thomas Matthews
    In a typical implementation of the Visitor pattern, the class must account for all variations (descendants) of the base class. There are many instances where the same method content in the visitor is applied to the different methods. A templated virtual method would be ideal in this case, but for now, this is not allowed. So, can templated methods be used to resolve virtual methods of the parent class? Given (the foundation): struct Visitor_Base; // Forward declaration. struct Base { virtual accept_visitor(Visitor_Base& visitor) = 0; }; // More forward declarations struct Base_Int; struct Base_Long; struct Base_Short; struct Base_UInt; struct Base_ULong; struct Base_UShort; struct Visitor_Base { virtual void operator()(Base_Int& b) = 0; virtual void operator()(Base_Long& b) = 0; virtual void operator()(Base_Short& b) = 0; virtual void operator()(Base_UInt& b) = 0; virtual void operator()(Base_ULong& b) = 0; virtual void operator()(Base_UShort& b) = 0; }; struct Base_Int : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_Long : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_Short : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_UInt : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_ULong : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_UShort : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; Now that the foundation is laid, here is where the kicker comes in (templated methods): struct Visitor_Cout : public Visitor { template <class Receiver> void operator() (Receiver& r) { std::cout << "Visitor_Cout method not implemented.\n"; } }; Intentionally, Visitor_Cout does not contain the keyword virtual in the method declaration. All the other attributes of the method signatures match the parent declaration (or perhaps specification). In the big picture, this design allows developers to implement common visitation functionality that differs only by the type of the target object (the object receiving the visit). The implementation above is my suggestion for alerts when the derived visitor implementation hasn't implement an optional method. Is this legal by the C++ specification? (I don't trust when some says that it works with compiler XXX. This is a question against the general language.)

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  • Static methods on ASP.NET web sites

    - by Grant
    Hi, i was wondering.. if i have a static method on an asp.net web site (plain vanilla), is that accessible by all users of all sessions? I guess what i am saying is the single instance of a method available to each client? or is there 1 instance for all clients for the site..

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  • Single Instance Storage layers

    - by Moo
    Hi, I have a data storage requirement which is an excellent candidate for single instance storage and deduplication. Can anyone suggest any .Net compatible libraries or systems which handles SIS and deduplication, either with SQL Server as an actual back end or its own high performance storage engine? What have peoples experiences been with such engines, and are there any pit falls to watch out for? Regards Moo

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  • Help: Instance Variables & Properties [iPhone]

    - by Devoted
    In something like this: @interface Control_FunViewController : UIViewController { UITextField *nameField; UITextField *numberField; } @property (nonatomic, retain) IBOutlet UITextField *nameField; @property (nonatomic, retain) IBOutlet UITextField *numberField; I understand that "UITextField *nameField;" is an instance variable and "@property ..." is a property. But what do these individual things do? I guess what I'm really asking is how the property is used for example in the implementation file (.m)

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  • Changing Graphic Instance using ActionScript

    - by Luke Duddridge
    Hi, I was wondering if it is at all possible to change the "Graphic" used in a frame dynamically using actionscript. I was hoping to either change the image the Graphic is an instance of or change the Graphic I am using in the current frame. Cheers Addition: Could I have a layer for each Graphic and then using action script choose which layer shows?

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  • C# Copying instance variable to local variable in functions of same class

    - by NickLarsen
    I have been looking through some code on an open source project recently and found many occurrences of this kind of code: class SomeClass { private int SomeNumber = 42; public ReturnValue UseSomeNumber(...) { int someNumberCopy = this.SomeNumber; if (someNumberCopy > ...) { // ... do some work with someNumberCopy } else { // ... do something else with someNumberCopy } } } Is there any real benefit to making a copy of the instance variable?

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  • Easiest way to find previous instance of an application

    - by Yogi Yang 007
    I have rewritten a VB6 based application developed in Delphi, which should have only one instance running. How can I do this with minimum of code? In VB6 we just have to use one single line of code If App.PrevInstance Then 'Take some action End If On goggling I did find a solution but it is very length and we have to mess with .drp file. I do not want to do that. I want something simpler.

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