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• How to write a value validation method for core data?

  - by mystify

  The docs say: you should implement methods of the form validate:error:, as defined by the NSKeyValueCoding protocol so lets say I have an attribute which is an int: friendAge I want to make sure that any friend may not be younger than 30. So how would I make that validation method? -validateFriendAge:error: What am I gonna do in there, exactly? And what shall I do with that NSError I get passed? I think it has an dictionary where I can return a humanly readable string in an arbitrary language (i.e. the one that's used currently), so I can output a reasonable error like: "Friend is not old enough"... how to do that?

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• Python 3: Most efficient way to create a [func(i) for i in range(N)] list comprehension

  - by mejiwa

  Say I have a function func(i) that creates an object for an integer i, and N is some nonnegative integer. Then what's the fastest way to create a list (not a range) equal to this list mylist = [func(i) for i in range(N)] without resorting to advanced methods like creating a function in C? My main concern with the above list comprehension is that I'm not sure if python knows beforehand the length of range(N) to preallocate mylist, and therefore has to incrementally reallocate the list. Is that the case or is python clever enough to allocate mylist to length N first and then compute it's elements? If not, what's the best way to create mylist? Maybe this? mylist = [None]*N for i in range(N): mylist[i] = func(i)

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• Apache mod_rewrite replace characters in REQUEST_URI

  - by frio80

  I'm trying to write some .htaccess rules that replace certain characters in the REQUEST_URI parameter. Specifically, I want to replace the following: "<" = &lt; "" = &gt; "'" = &apos; '"' = &#x22; ")" = &#x29; "(" = &#x28; Example URL could be http://www.example.com/?<script>alert(1)</script>&q=")("<script') I've tried a whole bunch of methods with no success. Can someone point me in the right direction? Thanks.

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• Pass structured data from C++ app to ASP.NET web service.

  - by Odrade

  I have Visual C++ application that needs to communicate with a ASP.NET web service. Specifically, the app needs to pass structured data (e.g. objects that contain lists of structures, etc) as a parameter to one of the service methods. The C++ application is already generating an xml document that contains this data. The document is generating using an xml library, so it should always well-formed. What is a good method for passing this data to the web service? I'm thinking about passing the document to the web service as a string parameter, then deserializing to a .NET object based on an xsd. But, I hear that passing an xml doc as a string parameter is not recommended. So, my questions: What are the pitfalls associated with sending the document as a string parameter, assuming that the document itself is always well-formed? Assuming the above is a bad idea, what are some good alternate approaches?

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• R.layout.main error, no solutions have worked

  - by user3404278

  I am just beginning to develop for Android. The tutorial book I am using uses the code below, but, put simply, it does not work. As I've searched for an answer, I find that none of the solutions people say have rid them of this error have worked for me. Here is a list of methods that did not work. -Cleaning: It just said it couldn't clean until I resolved the error. -Building the Project: It built it, but the error did not go away. -Deleting import R: The error did not go away. -Renaming import R to import me.package.R: The error persisted. Here is the code that is generating the error. public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } Can anyone help me out?

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• Qt: QAbstractItemModel and 'const'

  - by Eye of Hell

  Hello. I'm trying to use a QTreeView for a first time, with a QAbstractItemModel. And instantly it's a problem: QAbstractItemModel interface declares methods as 'const', assuming they will not change data. But i want a result of SQL query displayed, and returning data for a record with specified indeq REQUIRES to use QSqlQuery::seek() that is a non-const. Is it any 'official' guideline to use a QAbstractItemModel with data that MUST be changed in order to get number of items, data per item etc? Or i must hack C++ with const casts?

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• Best way to call other class view in iphone?

  - by aman-gupta

  Hi, Generally i call my other class view by creating a pointer of delegate and then call the other class by using its link as below:- First Way :- Mydelegate *ptr = (Mydelegate *)[[UIApplication sharedApplication]delegate]; [self.navigationController pushViewController:ptr.NextClasspointer animated:YES]; Second Way :- Create a pointer of that class which u want to call :-- NextClass *nextptr = [[NextClass alloc]initWithnibName:@"NextClass" bundle:nil]; [self.navigationController pushViewController:nextptr animated:YES]; [nextptr release]; nextptr = nil; These above two methods i generally used but my problem is that which one is best for big project so that my stack problem will be removed I mean memory issue will be solved.And is it necessary to release pointer in first and second case is the way i release is correct or wrong Please help me Thanks in Advance

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• C++ get method - returning by value or by reference

  - by HardCoder1986

  Hello! I've go a very simple question, but unfortunately I can't figure the answer myself. Suppose I've got some data structure that holds settings and acts like a settings map. I have a GetValue(const std::string& name) method, that returns the corresponding value. Now I'm trying to figure out - what kind of return-value approach would be better. The obvious one means making my method act like std::string GetValue(const std::string& name) and return a copy of the object and rely on RVO in performance meanings. The other one would mean making two methods std::string& GetValue(...) const std::string& GetValue(...) const which generally means duplicating code or using some evil constant casts to use one of these routines twice. #Q What would be your choice in this kind of situation and why?

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• Rails: Thread won't affect database unless joined to main Thread

  - by hatboysam

  I have a background operation I would like to occur every 20 seconds in Rails given that some condition is true. It kicked off when a certain controller route is hit, and it looks like this def startProcess argId = self.id t = Thread.new do while (Argument.isRunning(argId)) do Argument.update(argId) Argument.markVotes(argId) puts "Thread ran" sleep 20 end end end However, this code does absolutely nothing to my database unless I call "t.join" in which case my whole server is blocked for a long time (but it works). Why can't the read commit ActiveRecords without being joined to the main thread? The thread calls methods that look something like def sample model = Model.new() model.save() end but the models are not saved to the DB unless the thread is joined to the main thread. Why is this? I have been banging my head about this for hours.

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• iPhone : Primitives getters and setters

  - by Burf2000

  I feel a bit miffed at the moment, I done a few iPhone projects that use floats and ints etc and all is fine. I now using OpenGL and GLFloat[] C arrays etc and it seems unless I make methods to set / get them it crashes on the device (not the simulator). Now as these are not setup as properties (I don't think c arrays can) it kind of makes sense. However the project has been working for months without them. It seems something in the code is wiping out anything float / ints to the point that the debugger can see an assigned value but accessing it crashes the phone. As soon as I think I know something for this platform, something changes my mind lol.

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• How do I change the background image of my iPhone app?

  - by alJaree

  Hello I have looked around and found some code which so called chooses an image from an array of image objects, but cant find an explanation. I would like to make my app have a background image and the user can select next and previous buttons to scroll through some full screen images, setting them as the background image as they scroll. I know how to do this in java, but cant seem to do it for this app. How or what code is linked to a next button to grab the next image in the array and reverse for the back button? Then that needs to be displayed obviously. I have used a layered architecture with a MVC style approach but cant seem to put it together with Objective-C. Would the buttons call the appropriate methods of the so called delegates, which the delegates handle fetching and returning the Images? Would the buttons use the returned images and actually handle the redrawing? I would really appreciate the help. Regards Jarryd

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• What should I name instances of a twisted.internet.defer.Deferred?

  - by slacy

  I'm writing code using Twisted, and having trouble coming up with a sensible variable name for my twisted internet deferred's. Here are my candidates: d : Too generic, too short, violates pylint rule C0103. def : Conflicts with function defintion builtin. defer : Conflicts with module twisted.internet.defer deferred : OK but pretty long cb : Still too short, violates pylint C0103, conflicts with many callback method names. cback : Too Weird? callback : Conflicts with method Deferred.callback() I'm looking for other suggestions. It seems like most of the Twisted example code uses "d" which is fine for simple invocations, but when you're passing Deferred's around to methods and storing them as member variables, it's really far too descriptive.

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• Java: global values inside a class?

  - by HH

  I want less methods. I want a common global TestClass from which I could use any of its value inside the class. import java.util.*; import java.io.*; public class TestClass { TestClass(String hello){ String hallo = hello; String halloSecond = "Saluto!"; } public static void main(String[] args) { TestClass test = new TestClass("Tjena!"); System.out.println("I want "Tjena!": " + test.hallo); TestClass testSecond = new TestClass("1"); System.out.println("I want Saluto!:" + test.halloSecond); System.out.println("I want Saluto!:" + testSecond.halloSecond); } }

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• How to access a method of a closure's parent object?

  - by Bytecode Ninja

  I have defined a class named MyClass and I have defined two methods myMethod1 and myMethod2 for it: function MyClass() {} MyClass.prototype.myMethod1 = function() {...}; MyClass.prototype.myMethod2 = function() {...}; Inside myMethod1, I use jQuery and there's a callback closure defined there: MyClass.prototype.myMethod2 = function() { $.jQuery({success: function(data) { this.myMethod2(); }, ...}); } Now the problem is that this no longer is referring to MyClass. The question is how can I refer to it? At the moment I have assigned it to a variable named thisObj and access it this way: MyClass.prototype.myMethod2 = function() { var thisObj = this; $.jQuery({success: function(data) { thisObj.myMethod2(); }, ...}); } Is there a better way to access MyClass.this from the closure nested in myMethod2? Thanks in advance.

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• How do I dynamically change the path_to()?

  - by Angela

  I currently have three methods which I want to collapse into one: def send_email(contact,email) end def make_call(contact, call) return link_to "Call", new_contact_call_path(:contact => contact, :call => call, :status => 'called') end def make_letter(contact, letter) return link_to "Letter", new_contact_letter_path(:contact => contact, :letter => letter, :status => 'mailed') end I want to collapse the three into one so that I can just pass the Model as one of the parameters and it will still correctly create the path_to. I am trying to do this with the following, but stuck: def do_event(contact, call_or_email_or_letter) model_name = call_or_email_or_letter.class.name.tableize.singularize link_to "#{model_name.camelize}", new_contact_#{model_name}_path(contact, call_or_email_or_letter)" end

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• Making a PHP object behave like an array?

  - by Mark Biek

  I'd like to be able to write a PHP class that behaves like an array and uses normal array syntax for getting & setting. For example (where Foo is a PHP class of my making): $foo = new Foo(); $foo['fooKey'] = 'foo value'; echo $foo['fooKey']; I know that PHP has the _get and _set magic methods but those don't let you use array notation to access items. Python handles it by overloading __getitem__ and __setitem__. Is there a way to do this in PHP? If it makes a difference, I'm running PHP 5.2.

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• Save the output of a command in a string in linux using python

  - by user1657901

  I am using Fedora 17 xfce and I am programming in Python 2.7.3. Fedora uses a package manager called yum. I have a python script that searches for packages like this: import os package = raw_input("Enter package name to search: ") os.system("yum list " + package) So I want python to check if in the output of this command exists the words "No matching packages to list". I checked a similar question and I tried some methods [http://stackoverflow.com/questions/2502833/python-store-output-of-subprocess-call-in-a-string][1] but the string contained only the first line of the output. Thanks in advance

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• Extract data from uint8 to double

  - by HADJ AMOR HASSEN

  I have a C function receiving a uint8 pointer with another parameter which is its size (number of bytes). I want to extract double data from this buffer. Here is my code: Write(uint8* data, uint8 size) /* data and size are given by a callback to my function)*/ { double d; for (i = 0; i < size; i++) { d = ((double*)&data)[i]; printf(" d = %d\n"); } } The problem is that I am not receiving what I am sending within an external hardware. I guess that my cast is wrong. I tried other methods but without any good result. I am still not able to get what I send.

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• NoMethodError when trying to invoke helper method from Rails controller

  - by John Topley

  I'm getting a NoMethodError when trying to access a method defined in one of my helper modules from one of my controller classes. My Rails application uses the helper class method with the :all symbol as shown below: class ApplicationController < ActionController::Base helper :all . . end My understanding is that this should make all of my controller classes automatically include all of the helper modules within the app/helpers directory, therefore mixing in all of the methods into the controllers. Is this correct? If I explicitly include the helper module within the controller then everything works correctly.

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• When to use try/catch

  - by coffeeaddict

  I'm always finding myself wanting to put a try/catch around the lets say Business Layer methods. But I feel though that I don't need a try/catch if I'm simply rethrowing it up to the Presentation Layer. Is that right? I should not be rethrowing an exception from code that's wrapped in a try/catch in a BL method and should be letting the caller which would be from the Presentation Layer code be using a try/catch to handle it there? The BL method will throw an error without the try/catch anyway..the compiler will. So it wouldn't make sense to use a try/catch in a BL method that's to be consumed by a layer higher up correct?

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• Using Java method to display HTML code

  - by javArc

  Hey folks, ok so this is my problem, I need to display HTML code in a jsp, which wouldn't be a problem, except a requirement for this project is that we place all the code in a public class file and have seperate methods for each chunk(header, sidebar footer, etc). Now here's where i'm confused: "Your method should take the PrintWriter as a parameter to print out each line of HTML, and should have a return type of void" What does that mean? How do I pass the PrintWriter into a method? Does this make sense to anyone?

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• PHP image resize on the fly vs storing resized images

  - by Pablo

  I'm building a image sharing site and would like to know the pros and cons of resizing images on the fly with php and having the resized images stored. Which is faster? Which is more reliable? how big is the gap between the two methods in speed and performance? Please note that either way the images go through a PHP script for statistics like views or if hotlinking is allow etc... so is not like it will be a direct link for images if i opt to store the resize images. I'll appreciated your comments or any helpful links on the subject, Thanks.

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• wpf get access to other classes

  - by Calvin

  I am currently working on a wpf application. There are some methods in other classes in which I want to trigger to do some work instead of trying to figure out how to rewrite them in. How is it that I can get to those classes? Would I have to for example instantiate the class? If so, once I instantiate it, how would I be able access them. Keep in mind that these classes have abstract classes on top of abstract classes.

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• two classes contain objects of each other

  - by Julz

  hi, i hope there's a simple answer to this. without getting too complicated i have two classes. an "Animal" and a "Cell" Cell contains an Animal as a member. Animal has methods that accept Cells in their parameters. i'm just confused as to how i #include each class the others header? i've only ever had to go up a chain of classes and just included the last class header in the next and so on, but this circular situation has me a bit lost. i hope that makes sense, any help greatly appreciated.

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• Java vs C# - AddActionListener vs event subscription

  - by S.O.

  Very simple question from one somewhat new to Java: when adding an event handler (or whatever it is called in Java) to a Control, MUST it be an object? I mean, in C# I can do control.event += System.eventHandler(methodThatHandlesEvent) Sure, that's because we have delegate types in C#, but I was wondering if I can choose which method would be called when an event is raised in Java? I mean, in Java I can have something like control.AddActionListener(objectWhichClassImplementsActionListener) And then I have the stupid actionPerformed method in this class, which is the only method that is called. I know, there are more kinds of listeners, but I can't have a "ActionListenerHandler" class in which I implement several actionPerformed methods that can be assigned to different controls?

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