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  • Objective C instance variables - Newbie

    - by Dwayne King
    OK - so I'm sure my confusion here is just a result of being stuck in a "Java mindset" and not understanding how Obj C differs in this case. In Java, I can declare a variable in a class, like this, and each instance of that class will have it's own: MyClass { String myVar; MyClass() { // constructor } } In Obj C I tried to do the same thing by declaring a variable only in the .m file like this: #import "MyClass.h" @implementation MyClass NSString *testVar; @end My expectation here was that this variable has a scope limited to this class. So I created a second class (identical): #import "MySecondClass.h" @implementation MySecondClass NSString *testVar; @end What I'm seeing (and has me baffled) is that changing the variable in one class, affects the value seen in the other class. In fact, if I set a breakpoint, and then "Jump to Definition" of the variable, it takes me to th I've created an extremely small XCode project that demonstrates the problem here Nothing more humbling than moving to a new language :) Thanks in advance.

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  • Hibernate - One design problem

    - by Yatendra Goel
    I am learning Hibernate from the tutorial on JBoss website. I have a confusion in a code example located here. There is a Cat class code at 4.1. A simple POJO example. This Cat class has a reference to his mother as private Cat mother; Q1. If the class has an identifier property as id, then wouldn't it be better to store the cat's mother's id instead of cat's mother object. means instead of private Cat mother; wouldn't it be better to have private long motherId; `

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  • iPhone - How to use #define in Universal app

    - by Satyam svv
    I'm creating universal app that runs oniphone and ipad. I'm using #define to create CGRect. And I want to use two different #define - one for iPhone and one for iPad. How can I declare them so that correct one will be picked by universal app.......... I think I've to update little more description to avoid confusion. I've a WPConstants.h file where I'm declaring all the #define as below #define PUZZLE_TOPVIEW_RECT CGRectMake(0, 0, 480, 100) #define PUZZLE_MIDDLEVIEW_RECT CGRectMake(0, 100, 480, 100) #define PUZZLE_BOTTOMVIEW_RECT CGRectMake(0, 200, 480, 100) The above ones are for iphone. Similarly for iPad I want to have different #define How can I proceed further?

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  • Is shortening properties names worth it?

    - by raam86
    in how to node Blog rolling with node.js and mongoDB the author mentions it's a good idea to shorten proprieties names: ....oft-reported issue with mongoDB is the size of the data on the disk... each and every record stores all the field-names .... This means that it can often be more space-efficient to have properties such as 't', or 'b' rather than 'title' or 'body', however for fear of confusion I would avoid this unless truly required! I am aware of solutions of how to do it I am more intrested in when is it truly required?

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  • Does MVC replace traditional manually created BLL?

    - by used2could
    I'm used to creating the UI, BLL, DAL by hand (some times I've used LINQ-to-SQL or SubSonic for the DAL). I've done several small projects using MVC since its release. On these projects I've still continued to write a BLL and DAL by hand and then incorporate those into the MVC's models/controllers. I'm looking to optimize my time on projects this seems like overkill and a potential waste of time. Question Would it be acceptable to roll a DAL such as SubSonic and directly use it in the Models/Controllers of my MVC web app? Now the models & controllers would act as the BLL. I just see this as a major timesaver to not have to worry about another tier. UPDATE: I just wanted to add that my concern isn't really with the DAL (I frequently use SubSonic and NH) but rather focus on the BLL. Sorry for the confusion.

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  • How to deal with multiple Facebook requests simultaneously

    - by Peter Warbo
    I'm using the Facebook SDK for my app. I have created a singleton class FacebookHelper to deal with all Facebook related logic. Whenever I make a Facebook request (i.e download friends) I set an enum i.e FacebookRequestDownloadFriends so that FacebookHelper knows how to handle errors and success for that request (since handling can be different between the different requests) This solution has worked out fine until now, because now I'm doing 2 Facebook Requests at the same time so when I set the enum for the first request i.e FacebookRequestDownloadFriends and then it will be overwritten just shortly with another request FacebookRequestDownloadEvents, so there will be confusion obviously. How can I deal with this issue without having to refactor too much code?

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  • What c# equivalent encoding does Python's hash.digest() use ?

    - by The_AlienCoder
    I am trying to port a python program to c#. Here is the line that's supposed to be a walkthrough but is currently tormenting me: hash = hashlib.md5(inputstring).digest() After generating a similar MD5 hash in c# It is absolutely vital that I create a similar hash string as the original python program or my whole application will fail. My confusion lies in which encoding to use when converting to string in c# i.e ?Encoding enc = new ?Encoding(); string Hash =enc.GetString(HashBytes); //HashBytes is my generated hash Because I am unable to create two similar hashes when using Encoding.Default i.e string Hash = Encoding.Default.GetString(HashBytes); So I'm thinking knowing the deafult hash.digest() encoding for python would help

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  • How messages flows between computers connected with Internet or LAN ?

    - by Praveen
    Hi All, I have been doing Windows programming in .Net since last two years. Now I am shifting to web programming so I just stuck in understanding the fundamentals of web programming, after googling I came to StackOverflow to learn from all of you great guys. My confusion is about how messages flow between systems in distributed enviornment ? I mean suppose I want to send a message "Hello" to a system connected to LAN or Internet, then what will be the steps taken to send the message. Second thing is suppose my system is "A" and I wana send message to system "B" which is connected via a wire, so how the message flows on wire and how system "B" reads it from the wire ? Please someone explain me in a layman terms. Thank you all in advance.

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  • NoneType has no attribute Append

    - by Rosarch
    I'm new to Python. I can't understand why a variable is None at a certain point in my code: class UsersInRoom(webapp.RequestHandler): def get(self): room_id = self.request.get("room_id") username = self.request.get("username") UserInRoom_entities = UserInRoom.gql("WHERE room = :1", room_id).get() if UserInRoom_entities: for user_in_room in UserInRoom_entities: if user_in_room.username == username: user_in_room.put() # last_poll auto updates to now whenenever user_in_room is saved else: user_in_room = UserInRoom() user_in_room.username = username user_in_room.put() UserInRoom_entities = [] UserInRoom_entities.append(user_in_room) // error here # name is `user_at_room` intead of `user_in_room` to avoid confusion usernames = [user_at_room.username for user_at_room in UserInRoom_entities] self.response.out.write(json.dumps(usernames)) The error is: Traceback (most recent call last): File "C:\Program Files\Google\google_appengine\google\appengine\ext\webapp\__init__.py", line 507, in __call__ handler.get(*groups) File "path\to\chat.py", line 160, in get AttributeError: 'NoneType' object has no attribute 'append' How is this possible? I'm setting UserInRoom_entities = [] immediately before that call. Or is something else the None in question?

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  • Fetching a result twice with deferend name

    - by user1799842
    I have 1 table with tasks named opentask:columns: id,title,description,expires,creator_id,creator_name, executer_id, executer_name, priority_id, status_id1 table with users named user: with columns: user_id, username What I want is to create a query where there will be all columns from opentask table where the executer_id will be equal to the user_id of user table AND the creator_id will be equal to the user_id again. This creates a confusion because the first equality excludes the second.So I need somehow to create a query where I will include the usernames for the executer with something like where "opentask.executer_id=user_user_id" and at the same time I will include the username again (as a differend name?) for the creator with something like "where opentask.executer_id=user_user_id"So I try this, which of course I know that is missing something, can you help? SELECT DISTINCT id, title, description, expires, creator_id, executer_id, oc_opentask.priority_id, oc_opentask.status_id, priority_name, status_name, user_id, username, (SELECT username FROM oc_opentask, oc_user WHERE oc_opentask.creator_id=oc_user.user_id) AS username2 FROM oc_opentask, oc_opentask_priority, oc_user, oc_opentask_status WHERE oc_opentask.priority_id=oc_opentask_priority.priority_id AND oc_opentask.executer_id=oc_user.user_id AND oc_opentask.status_id=oc_opentask_status.status_id ORDER BY oc_opentask.expires DESC

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  • Java Inheritance Concept Understanding

    - by Nirmal
    Hello All.... I am just refreshing the oops features of the java. So, I have a little confusion regarding inheritance concept. For that I have a following sample code : class Super{ int index = 5; public void printVal(){ System.out.println("Super"); } } class Sub extends Super{ int index = 2; public void printVal(){ System.out.println("Sub"); } } public class Runner { public static void main(String args[]){ Super sup = new Sub(); System.out.println(sup.index+","); sup.printVal(); } } Now above code is giving me output as : 5,Sub. Here, we are overriding printVal() method, so that is understandable that it is accessing child class method only. But I could not understand why it's accessing the value of x from Super class... Thanks in advance....

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  • Different RegisterWindowMessage() names appear the same

    - by Mike Trader
    Using the C/C++ Windows API RegisterWindowMessage() I am using the name of the application as the message name. Next I call CreatMutex() using the same name so that I can tell if it already exists. If it does, I know this application is already running and not to launch a second instance of it. THis is the operation of my function Running() My confusion is over the message name. It seems that "AutoConvert.exe" and "AutoAppend.exe" are interpreted as the same name. Why?

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  • Httpd Process High memory usage and slow page loads

    - by Abs
    Hello all, I am running wampserver on my windows vista machine. I have been doing this for a long time and it has been working great. I have completed loads of projects with this setup. However, today, without me changing anything (no configuration etc) only PHP code changes, I find that every time I load pages of my site (those with user sessions or access the database) are really slow to load - Over 30 seconds, they use to take 1 or 2 seconds. When I have a look at the task manager, I can see on page loads the httpd process jumps from 10mb to 30mb, 90mb, 120mb, 250mb and then back down again. I have tested previous php code projects and they seem to all be slow as well! What is going on? Thanks all for any help on this confusion issue!

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  • C++ : Swapping template class elements of different types?

    - by metamemetics
    template< class T1, class T2 > class Pair { T1 first; T2 second; }; I'm being asked to write a swap() method so that the first element becomes the second and the second the first. I have: Pair<T2,T1> swap() { return Pair<T2,T1>(second, first); } But this returns a new object rather than swapping, where I think it needs to be a void method that changes its own data members. Is this possible to do since T1 and T2 are potentially different class types? In other words I can't simply set temp=first, first=second, second=temp because it would try to convert them to different types. I'm not sure why you would potentially want to have a template object that changes order of its types as it seems that would cause confusion but that appears to be what I'm being asked to do.

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  • Handling the distinction between undefined- and null-parameters in JavaScript

    - by Jakob
    I know very well that null and undefined are distinct in JavaScript. However, I can't seem to decide whether or not use that fact when my own functions are passed one of those as its argument. Or, expressed in a different way, should myFoo(undefined) return the same thing as myFoo(null) or is everything fine if it doesn't? Or, in yet another case, since myBar(1, 2, 3) is the same thing as myBar(1, 2, 3, undefined, undefined), should myBar(1, 2, 3, null, null) return the same thing as myBar(1, 2, 3)? I feel that there's potential for confusion in both cases and that a library should probably follow a convention when handling null/undefined. I'm not really asking for personal opinions (so please express those as comments rather than answers). I'm asking if anyone knows if there is a best practice that one should stick to when it comes to handling this distinction. References to external sources are very welcome!

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  • Allow a new line anywhere in the regex?

    - by Scott Chamberlain
    I am having a find a replace in a bunch of RTF documents, The basic pattern I need is \{(?:\\\*)?\\field\\fldlock\{\\\*\\fldinst ?MERGEFIELD ?((?:\\.*?)?[\w\[\]]+?)(?:\\.*?)?\}(?:\{\\fldrslt\})?\} However I then found out there could potentialy be a newline before each slash, so it turned in to this. \{(?:\s*\\\*)?\s*\\field\s*\\fldlock\s*\{\s*\\\*\s*\\fldinst\s*MERGEFIELD\s*((?:\\.*?)?[\w\[\]]+?(?:\s*\\.*?)?)?\s*\}(?:\s*\{\s*\\fldrslt\s*\})?\s*\} But then I hit this it fails fees totaling $\protect {\field\fldlock{\*\fldinst MERGEFIELD ENTEROUTSTANDINGVETERINARYF EES}}\plain\f0\fs24\prot Is there way have to have it match a new line anywhere in the search too without adding (?:\r?\n)? everywhere? EDIT To clear up confusion on the new lines. I need to keep the newlines in the document, I only want to remove the newlines if they are inside my match, so in the final example I posted it should replace fees totaling $\protect {\field\fldlock{\*\fldinst MERGEFIELD ENTEROUTSTANDINGVETERINARYF EES}}\plain\f0\fs24\prot with fees totaling $\protect ENTEROUTSTANDINGVETERINARYFEES\plain\f0\fs24\prot

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  • Is there any way to validate the Open Graph protocol meta tags for Facebook integration?

    - by John
    Is there any way to validate the Facebook Open Graph protocol meta tags in the head section of my website? Code below. <meta property="og:title" content="my content" /> <meta property="og:type" content="company" /> <meta property="og:url" content="http://mycompany.com/" /> <meta property="og:image" content="http://mycompany.com/image.png" /> <meta property="og:site_name" content="my site name" /> <meta property="fb:admins" content="my_id" /> <meta property="og:description" content="my description" /> -edit- I mean validating the html. Sorry for the confusion! Right now my site isn't valid because of these tags.

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  • Closed Source Java Applications

    - by Paul
    I am taking programming courses and we have been discussing Open Source and having a bit of an argument over the confusion. Just because Java is Open Source, the licensing on developed applications starts at the developer, correct? Someone is arguing about the use of code from a complete program just because "Java is Open Source". If I write a Java application, what are the limitations on how I can distribute it or how someone else can use it? Assume here that I DO NOT want someone having access to my source. Thanks

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  • Why do we need a private constructor?

    - by isthatacode
    if a class has a private constructor then it cant be instantiated. so, if i dont want my class to be instantiated and still use it, then i can make it static. what is the use of a private constructor ? Also its used in singleton class, except that, is there any othe use ? (Note : The reason i am excuding the singleton case above is because I dont understand why do we need a singleton at all ? when there is a static class availble. You may not answer for my this confusion in the question. )

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  • What is the differnce between an Oracle and Microsoft schema?

    - by Tarzan
    I am working on an enterprise project. Some of the team has an Oracle background and some has a Microsoft SQL Server background. There is much confusion when we talk about schemas. I am trying to provide some clarity. Is this an accurate way to describe the difference in the meaning of schemas between the two technologies? An Oracle schema is associated with a single user and consists of the objects owned by the user. A MS SQL Server schema schema is a namespace.

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  • Session State ArrayList in Shopping Cart ASP.NET

    - by user330342
    Hi guys, I'm creating a shopping cart application and I'm having some issues with implementing a session state for my arraylist. in my page load i declared if (Session["Cart"] == null) { Session["Cart"] = new ArrayList(); } else { ArrayList cart = (ArrayList)Session["Cart"]; } to create the session if it doesn't exist yet. then i have an event handler for a button to add items to the arraylist protected void onClick_AddBooking(object sender, EventArgs e) { int ClassID = Convert.ToInt32(Request.QueryString.Get("Class_Id")); ArrayList cart1 = new ArrayList(); cart1 = Session["Cart"]; cart1.Add(ClassID); i'm guessing i just don't know how to handle session states yet, thus the confusion. I'm essentially storing the class_ID then when the student confirms i'll store that to the DB and associate that ID with the Class Details. Thanks in advance guys!

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  • Regarding C typedef struct

    - by Bruce Duncan
    I have multiple instances of typedef struct box so box box1, box box2 etc. The members of the struct are length, width, height etc. typedef struct { int width; int height; } box; box box1; box box2; How can I create a function that operates on all the width members of each box instance? My confusion is how do I pass a pointer to a typedef struct member that works across all instances of box. I know how to pass a pointer to a specific instance member like box1.width but how to pass .width and then do box1.width=value; box2.width=value; box3.width=value; within the function?

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  • is there a flag "M_FAST" in FreeBSD kernel for Malloc Call ?

    - by KaluSingh Gabbar
    if you know there is one, can you let me know what its for ? if not please say so : ) thanks. Signature : void * malloc(unsigned long size, struct malloc_type type, int flags); for example. other flags are... M_ZERO Causes the allocated memory to be set to all zeros. M_WAITOK Indicates that it is OK to wait for resources. If the request cannot be immediately fulfilled, the current process is put to sleep to wait for resources to be released by other processes. The malloc(), realloc(), and reallocf() functions cannot return NULL if M_WAITOK is specified.** This is the root of my confusion EDIT: The clarification for M_FAST is made in my answer below.

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  • What is the correct way to fix this Javascript closure

    - by sujoe
    I have been familiarizing myself with javascript closures and ran across this article http://blog.morrisjohns.com/javascript_closures_for_dummies.html Due to the closure, Example 5 does not work as expected. How would one modify result.push( function() {alert(item + ' ' + list[i])} ); to make the code work? function buildList(list) { var result = []; for (var i = 0; i < list.length; i++) { var item = 'item' + list[i]; result.push( function() {alert(item + ' ' + list[i])} ); } return result; } function testList() { var fnlist = buildList([1,2,3]); // using j only to help prevent confusion - could use i for (var j = 0; j < fnlist.length; j++) { fnlist[j](); } } testList(); Thanks!

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  • Are function arguments stored in a closure?

    - by Nick Lowman
    I was reading this great article about closures here and the example below outputs 'item3 undefined' three times. I understand why it outputs 'item3' three times as the functions inside buildList() all use the same single closure but why can't it access the 'list' argument? Why is it undefined? Is it because the argument is passed in after the closure has been created? function buildList(list) { var result = []; for (var i = 0; i < list.length; i++) { var item = 'item' + list[i]; result.push( function() {console.log(item + ' ' + list[i])} ); } return result; } function testList() { var fnlist = buildList([1,2,3]); // using j only to help prevent confusion - could use i for (var j = 0; j < fnlist.length; j++) { fnlist[j](); } }

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