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• LINQ query to navigate an object hierachy

  - by TesterTurnedDeveloper

  Let's say I have an object graph of Countries / States / Cities, like below: public class City { public string Name { get; set; } } public class State { public List<City> Cities { get; set; } } public class Country { public List<State> States { get; set; } } Is there a simple way to query a List<Country> to get all the cities?

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• Enums and inheritance

  - by devoured elysium

  I will use (again) the following class hierarchy: Event and all the following classes inherit from Event: SportEventType1 SportEventType2 SportEventType3 SportEventType4 I have originally designed the Event class like this: public abstract class Event { public abstract EventType EventType { get; } public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } with EventType being defined as: public enum EventType { Sport1, Sport2, Sport3, Sport4 } The original idea would be that each SportEventTypeX class would set its correct EventType. Now that I think of it, I think this approach is totally incorrect for two reasons: If I want to later add a new SportEventType class I will have to modify the enum If I later decide to remove one SportEventType that I feel I won't use I'm also in big trouble with the enum. I have a class variable in the Event class that makes, afterall, assumptions about the kind of classes that will inherit from it, which kinda defeats the purpose of inheritance. How would you solve this kind of situation? Define in the Event class an abstract "Description" property, having each child class implement it? Having an Attribute(Annotation in Java!) set its Description variable instead? What would be the pros/cons of having a class variable instead of attribute/annotation in this case? Is there any other more elegant solution out there? Thanks

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• how to convert the string into json object?

  - by Holicreature

  I use the ajax which sends back a string.. I want to convert the responsetext into a json object to process. I tried eval and also , but doesn't works... Wht to do? My code is function handleResponse() { if(httpa.readyState == 4){ var response = httpa.responseText; if(response!='empty') { alert(response); var foo = eval('(' +strJSON+ ')'); alert (foo); } } } // response alerts [{"id":"1","name":"Pepsodent 100g","selling_price":"28.75"},{"id":"2","name":"Pepsodent 40g","selling_price":"18.90"},{"id":"3","name":"Pepsodent brush","selling_price":"19.50"}]

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• How can I use Amazon's API in PHP to search for books?

  - by TerranRich

  I'm working on a Facebook app for book sharing, reviewing, and recommendations. I've scoured the web, searched Google using every search phrase I could think of, but I could not find any tutorials on how to access the Amazon.com API for book information. I signed up for an AWS account, but even the tutorials on their website didn't help me one bit. They're all geared toward using cloud computing for file storage and processing, but that's not what I want. I just want to access their API to search info on books. Kind of like how http://openlibrary.org/ does it, where it's a simple URL call to get information on a book (but their databases aren't nearly as populated as Amazon's). Why is it so hard to find the information I need on Amazon's AWS site? If anybody could help, I would greatly appreciate it.

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• Can I just release the top object (iPhone)?

  - by yar

  If I release the object that's holding a reference to the variable that I need to release, is that sufficient? Or must I release at every level of the containment hierarchy? I fear that my logic comes from working with a garbage collector for too long. For instance, I assigned to this property of a UIPickerView instance by hand instead of using IB @property(nonatomic, assign) id<UIPickerViewDelegate> delegate Since it's an assign property, I can't just release the reference after I assign it. When I finally release my UIPickerView instance, do I need to do this: [singlePicker.delegate release]; [singlePicker release]; or is the second line sufficient? Also: Are these assign properties the norm, or is that mostly for Interface Builder? I thought that retain properties were the normal thing to expect.

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• Test if a method is an override?

  - by Water Cooler v2

  Is there a way to tell if a method is an override? For e.g. public class Foo { public virtual void DoSomething() {} public virtual int GimmeIntPleez() { return 0; } } public class BabyFoo: Foo { public override int GimmeIntPleez() { return -1; } } Is it possible to reflect on BabyFoo and tell if GimmeIntPleez is an override?

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• Using a string as an object reference

  - by user317362

  I currently have a Javascript function that uses a string to reference an object name and acces its properties. I'm currently using eval() to get the the desired effect which I know is very, very wrong. Here is an example of how I'm currently achieving what I want: var stringToObjectRef = function() { var myTestVar = "myTestObject"; var myTestObject = { 'item1' : 100, 'item2' : 12, 'item4' : 18 }; var myValue = eval(myTestVar + '.item1'); alert(myValue); }(); I've tried using something like [myTestVar].item1, but this returns undefined. What is the correct syntax to achieve this? Thanks in advance.

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• What is the use of Java Interfaces? [closed]

  - by RayAllen

  Possible Duplicate: How will I know when to create an interface? Why do we need interfaces in Java? Instead of interface can't we write the methods directly in the class itself? Why do we need a separate interface?

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• Adding interfaces that won't be actually used

  - by devoured elysium

  I currently have two interfaces(that I'll name here IA and IB): interface IA { int Width; int Height; ... } interface IB { int Width; int Height; ... } that share the same two properties: they both have a Width and a Height property. I was thinking if there is any point in defining an IMatrix interface containing a Width and Height properties: interface IMatrix { int Width; int Height; } The thing is that although they share both the same properties, I won't make use of polymorphism with IMatrix in any of my coding: i.e., there won't by any situation where I'll want to use an IMatrix, I'll just want to use IA and IB. Adding an IMatrix seems more like over-engineering than other thing, but I'd like to ask you guys what your opinion is on the matter. Thanks

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• Using C++ from Objective C : how to allocate/deallocate?

  - by Dmitri Nesteruk

  Currently, my Objective C classes use C++ objects by doing a new when the owner is created, and calling delete when it is destroyed. But is there another way? I'd like to be able to declare, say, an auto_ptr whose scope lasts the duration of the Objective C class' lifetime.

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• How do I execute some code in a superclass after all the subclasses have been constructed?

  - by Thiado de Arruda

  Is there a way to do this in C#? I know that the subclass will call the superclass constructor before calling its own constructor, but what If I have some code on the superclass that should only be executed after all the subclasses constructors have been called?

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• Object directing to a property when accessed as an iterable

  - by ThE_JacO

  I'm trying to figure out if there's an elegant and concise way to have a class accessing one of its own properties when "used" as a dictionary, basically redirecting all the methods that'd be implemented in an ordered dictionary to one of its properties. Currently I'm inheriting from IterableUserDict and explicitly setting its data to another property, and it seems to be working, but I know that UserDict is considered sort of old, and I'm concerned I might be overlooking something. What I have: class ConnectionInterface(IterableUserDict): def __init__(self, hostObject): self._hostObject= hostObject self.ports= odict.OrderedDict() self.inputPorts= odict.OrderedDict() self.outputPorts= odict.OrderedDict() self.data= self.ports This way I expect the object to behave and respond (and be used) the way I mean it to, except I want to get a freebie ordered dictionary behaviour on its property "ports" when it's iterated, items are gotten by key, something is looked up ala if this in myObject, and so on. Any advice welcome, the above seems to be working fine, but I have an odd itch that I might be missing something. Thanks in advance.

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• The right way to implement communication between java objects

  - by imoschak

  I'm working on an academic project which simulates a rather large queuing procedure in java. The core of the simulator rests within one package where there exist 8 classes each one implementing a single concept. Every class in the project follows SRP. These classes encapsulate the behavior of the simulator and inter-connect every other class in the project. The problem that I has arisen is that most of these 8 classes are, as is logical i think, tightly coupled and each one has to have working knowledge of every other class in this package in order to be able to call methods from it when needed. The application needs only one instance of each class so it might be better to create static fields for each class in a new class and use that to make calls -instead of preserving a reference in each class for every other class in the package (which I'm certain that is incorrect)-, but is this considered a correct design solution? or is there a design pattern maybe that better suits my needs?

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• OFF descriptions

  - by Myx

  Hi: I'd like to make a scene that uses meshes and primitives (such as spheres, cylinders, boxes, etc). I was wondering if there are any recommendations with regard to where I can go to find .off files that describes complex meshes, such as mountains, rocks, trees, animals, etc. Thanks.

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• When to Use Properties & When to Use Methods?

  - by DaveDev

  Hi Guys I was looking at the following line of code foreach (PropertyInfo prop in t.GetProperties()) and I noticed that tprovides a method to return the type's properties instead of a property like t.Properties This makes me wonder why sometimes people use properties to make a type's data avilable and other times there's a method provided? Is there some logic behind the decision? Thanks Dave

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• Python and object/class attrs - what's going on?

  - by digitala

  Can someone explain why Python does the following? >>> class Foo(object): ... bar = [] ... >>> a = Foo() >>> b = Foo() >>> a.bar.append(1) >>> b.bar [1] >>> a.bar = 1 >>> a.bar 1 >>> b.bar [1] >>> a.bar = [] >>> a.bar [] >>> b.bar [1] >>> del a.bar >>> a.bar [1] It's rather confusing!

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• Why are interfaces unusable in PHP?

  - by streetparade

  I mean an interface definition without defining the return type makes it unusable? This makes more Clear Interface run { public function getInteger(); } class MyString implements run { public function myNumber() { } public function getInteger() { return "Not a number"; } } In Java every Interface has a return type like Integer,String,Void I know that PHP is unfortunately a loosly typed Language but isnt there a Solution for that Problem? Is it Possible to defining a Interface with a Return type like Integer?

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• Java inheritance question

  - by user247866

  So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = method-call();` // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void some-method(LIst<A> a) However, when I do: C c = new C(). c. some-method(b) I get an error that some-method is not applicable for the argument List, instead it's expecting to get List. Is there a good way to fix this problem? Many thanks!

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• How does Undo work?

  - by dontWatchMyProfile

  How does undo work? Does it copy all the managed objects every time any of the values change? Or does it only copy the actual changes together with an information which objects were affected? Is that heavy or lightweight?

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• iOS: Releasing Object Thats In Use (ARC)

  - by RileyE

  I have an object that I have created that subscribes to some NSNotificationCenter notifications, but it is being released, since I don't have a pointer to the instantiation. The instantiation has a delegate that will call a method back to another class I have, so I felt it unnecessary to also have a pointer to it, since the pointer doesn't serve any purpose. Basically, I have an instantiation of a class, DelegateListener (name is just for example purposes), which subscribes to some of the default NSNotificationCeneter's notifications. This instantiation isn't assigned to any pointer after the instantiation ends. The instantiation, however, has a property, delegate. I assign a value to that delegate during the instantiation. That delegate implements methods that I want the DelegateListener to call when the notifications that it subscribed to fire. The problem with this is that the instantiation of DelegateListener that I create gets released, unless if I assign it to a retained pointer. Is there a way to avoid this automatic release of my DelegateListener instantiation within ARC?

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• Using jquery statement within a jquery data object

  - by richardverbruggen

  As part of a jquery function u use this ajax post statement to get some reaction from a server. I want to pass some arguments to my test page. But these must be variables and are declared on the previous lines (iid and inst) How can i put these variables within the data object marked with the XX? iid = $(this).attr('iid'); inst = $(this).attr('inst'); $.post("test.php", { inst: XX, iid: XX},function(data){ alert("Data Loaded: " + data); });

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• onclick from an Object's button doesn't work

  - by 730

  I instantiate an object, with an argument which is a button. When the button of an instance is clicked, it should run a function, but it doesn't. In the full version of the code, Chrome gives this message in the console: "Uncaught TypeError: Cannot read property 'onclick' of undefined" HTML: <textarea id='txt' readonly rows='5' cols='40'></textarea> <button id='btn' type='button'>click</button> JS: var btn = document.getElementById('btn'); var txt = document.getElementById('txt'); var foo = new Foo(btn); function Foo(btn) { this.button = btn; } Foo.prototype.buy = function() { txt.value = 'Foo Bar'; }; Foo.button.onclick = function() { foo.buy(); }; Fiddle

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• how to make object public to all function in a class?

  - by thesocialhacker

  I've created a class that calls an object in the "__construct" how can i make this object available through out the class. class SocialMedia { function __construct() { $object = "whatever"; } } how can I access $object in the other funtions (which are static) from with in the class. I've tried to use "$this-object" but I get an error "$this when not in object context" when I try to call it from my other static functions.

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• Removing a character from JSONObject?

  - by RandomlyKnighted

  My JSONObject has some random characters contained within the string so I'm trying to remove them. I've tried this but with no luck. String result = s.substring(1, s.length() - 2); JSONObject json_data = new JSONObject(result); if (json_data.has("[")) { json_data.remove("["); } if (json_data.has("]")) { json_data.remove("]"); } if (json_data.has(",")) { json_data.remove(","); } It's still not removing the characters from the JSONObject. Am I checking the JSONObject for the characters incorrectly?

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• Difference between has-a and composed-of?

  - by fig-gnuton

  In OOP modeling, is there any distinction between a "has-a" relationship and a "composed-of" relationship?

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