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• referencing struct fields in c with square brackets and an index instead of . and ->?

  - by lsiebert

  Assuming I have a structure such as: typedef struct { char * string1; char * string2; } TWO_WORDS; such that all the fields are of the same type, and my main has TWO_WORDS tw; can I reference string1 with tw[0] and string2 with two[1]? If so: is this part of the c standard? do i have to cast the struct to an array first? what about fields which are different sizes in memory what about fields which are different types but the same size? can you do pointer arithmetic within a structure? -

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• Does this make any sense (Apple-documentation)?

  - by Paperflyer

  Here is a snippet of the official Apple Documentation of AudioBufferList (Core Audio Data Types Reference) AudioBufferList Holds a variable length array of AudioBuffer structures. struct AudioBufferList { UInt32 mNumberBuffers; AudioBuffer mBuffers[1]; }; typedef struct AudioBufferList AudioBufferList; Fields mNumberBuffers The number of AudioBuffer structures in the mBuffers array. mBuffers A variable length array of AudioBuffer structures. If mBuffers is defined as AudioBuffer[1] it is not of variable length and thus mNumberBuffers is implicitly defined as 1. Do I miss something here or is this just nonsense?

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• c++ classes & lua

  - by anon

  I want to have C++ objects that I can read/write in both C++ & Lua. I have looked at: http://www.lua.org/pil/28.html However, I do not like that solution, since my objects have constructors & destructors (and they are important as I use RAII and these take care of reference counts). What I don't like in the PIL solution is that the object is allocated in Lua's heap. What i want instead, is to create hte C++ object on my own, and just have lua have a way to do get/set on them. Does anyone have a good tutorial/link on this? Tanks!

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• Set a tab page on lload event of a form

  - by tanu

  i have a form with many tabs on it. I want to set a specific tab page to show on load of the form everytime i load the form I used TabPageControl1.SelectedTab=MyTabPage; but the value of selectedtab is null. It is throwing an exception that reference not set to an object. private void PreferencesForm_Load(object sender, EventArgs e) { this.cbxCustomDataType.DrawMode = DrawMode.OwnerDrawFixed; this.cbxCustomDataType.DrawItem += new DrawItemEventHandler(cbxCustomDataType_DrawItem); this.cbxColumnDataType.DrawMode = DrawMode.OwnerDrawFixed; this.cbxColumnDataType.DrawItem += new DrawItemEventHandler(cbxColumnDataType_DrawItem); GetProjectDetails(); this.preferencesTabControl.SelectedTab= tpCompareUpdate; }

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• Any way to stringify a variable id / symbol in Python?

  - by otz

  I'm wondering if it is possible at all in python to stringify variable id/symbol -- that is, a function that behaves as follows: >>> symbol = 'whatever' >>> symbol_name(symbol) 'symbol' Now, it is easy to do it on a function or a class (if it is a direct reference to the object): >>> def fn(): pass >>> fn.func_name 'fn' But I'm looking for a general method that works on all cases, even for indirect object references. I've thought of somehow using id(var), but no luck yet. Is there any way to do it?

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• Problem using a costum server control in a aspx

  - by gre3ns0ul

  Hi guys, i am having a issue. I already developed one class (my custom gridview) and i want use it on a .aspx That class is defined in app_code and compiled to the dll of the project. namespace MyCostumControls{  public class DropDownPagingGridView : GridView{ ... I already registered the control on the aspx page using <%@ Register Namespace="MyCostumControls" TagPrefix="ctrl" % and i can use in the page and works ok.. But i'm watching one problem. That class contains methods defined by me, than when i try to call them in code-behind sayd to me than they're not defined. In designed i don't see the reference to MyCostumControls, and when i try declare one field using protected global::MyCostumControls.MyCostumControls ddl_gv_errors, i cannot access to MyCostumControls namespace, Is because he's compiled to the project dll? I can access to all namespaces than are not contained in app_code. Solutions? Apreciate. Thanks

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• Spring security with database and multiple roles?

  - by Joe

  I'm trying to make an application using spring 3.0. Now I've decided to try my hand at spring-security and hibernate. I've already seen that it's possible to back it with a databasem and I've seen a reference to defining your own queries? Now the problem I have is that the tutorials I've been finding aren't too clear and that they assume that a user can only have one role. I want to give some users multiple roles. So I was thinking about a database scheme along the lines of: User: user_id username password registrationDate User_Role: user_id role_id Role: role_id rolename Now I was wondering if anyone had some pointers to some usefull tutorials/advice/comments.

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• Is "programmatically" a word? [closed]

  - by Lo'oris

  I can't find it on any of the online dictionaries I know: dict.org, word reference, urban dictionary, oxford paravia, garzanti. To my ears of a non-native speaker, it sounds horrible. Actually it sounds like a word made-up by another non-native speaker that wanted to say something, didn't know how, and just hacked in a word of his language. The only place I've read it other then user-created-content is the android documentation, so this might or might not be related. Do you happen to know where did it start to be used, why by did it spread so much, what does it really mean?

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• What is 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 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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• C# thread safety for class instances

  - by Steveng

  I am learning C# and I am confused with the thread safety of the copies of the class instances as below: eg: classA objA; classA objB = objA; objA.field1 = value2; //do I need lock around modification of field1? //let say we pass the objB to another thread objB.field1 = value1 //do I need a lock for objB because of the modification of field1? I am confused because coming from the background of C++, the class in C# is the reference type. If both objA and objB refer to the same memory underlying, then I would need a lock to protect the simultaneous writing to the field1. Could someone confirm with this or am I missing something? Thanks.

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• What's the best way to return something like a collection of `std::auto_ptr`s in C++03?

  - by Billy ONeal

  std::auto_ptr is not allowed to be stored in an STL container, such as std::vector. However, occasionally there are cases where I need to return a collection of polymorphic objects, and therefore I can't return a vector of objects (due to the slicing problem). I can use std::tr1::shared_ptr and stick those in the vector, but then I have to pay a high price of maintaining separate reference counts, and object that owns the actual memory (the container) no longer logically "owns" the objects because they can be copied out of it without regard to ownership. C++0x offers a perfect solution to this problem in the form of std::vector<std::unique_ptr<t>>, but I don't have access to C++0x. Some other notes: I don't have access to C++0x, but I do have TR1 available. I would like to avoid use of Boost (though it is available if there is no other option) I am aware of boost::ptr_container containers (i.e. boost::ptr_vector), but I would like to avoid this because it breaks the debugger (innards are stored in void *s which means it's difficult to view the object actually stored inside the container in the debugger)

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• C# background worker and timer loop

  - by Mike

  This is my first attempt of a Timer, if someone could help me out where I am going wrong it would be awesome. I'm trying to use a while loop where if the timer hits 30 seconds try to loop it again. private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) { System.Windows.Forms.Timer my_timer = new System.Windows.Forms.Timer(); my_timer = null; //int restartticker = 30000; while (true) { my_timer.Start(); if (my_timer.Equals(30000)) { watcherprocess1(); } my_timer = null; } } Object reference not set to an instance of an object. my_timer.Start();

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• Class templating std::set key types

  - by TomFLuff

  I have a class to evaluate set algebra but wish to template it. At the minute it looks a bit like this set.h: template<typename T> class SetEvaluation { public: SetEvaluation<T>(); std::set<T> evaluate(std::string in_expression); } set.cpp template<typename T> std::set<T> SetEvaluation<T>::evaluate(std::string expression) { std::set<T> result; etc etc... } But i'm getting undefined reference errors when compiling. Is it possible to declare the return type as std::set<T> and then pass std::string as the class template param. There are no errors in the class but only when I try to instantiate SetEvaluation<std::string> Can anyone shed light on this problem? thanks

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• How long people take to learn a new programming language?

  - by Cawas

  In general aspects, this might be a good reference for everyone. Having an idea of how long people take in average for properly learning how to code can give a very good idea on how dense or long is the path. Someone who never programmed should take weeks or months, even years maybe while someone who's already experienced in the area and know at least 2 different languages might take days, hours or even minutes to start coding. But other than being able to write code that runs, there are ways to write the same program, and it's much harder to get deep knowledge on that than actually being able to program. And sometimes languages differ a lot from one to another on that aspect as well. For instance, we should never have to worry with code-injection in JavaScript like we do in C. So, is there any place we can see some good numbers for how long it takes to learn a language, maybe divided into level of knowledge categories, languages and paradigms, etc?

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• What is the time complexity of LinkedList.getLast() in Java?

  - by i.

  I have a private LinkedList in a Java class & will frequently need to retrieve the last element in the list. The lists need to scale, so I'm trying to decide whether I need to keep a reference to the last element when I make changes (to achieve O(1)) or if the LinkedList class does that already with the getLast() call. What is the big-O cost of LinkedList.getLast() and is it documented? (i.e. can I rely on this answer or should I make no assumptions & cache it even if it's O(1)?)

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• is it possible to create a multi-project template that references n number of existing projects and

  - by jcollum

  The situation: I need to create about 40+ solutions that all reference 3 projects and have one project that is unique to each one. I'd like to create a multi-project template that does this, but from what I've read it looks like it's very difficult or impossible (related SO question, but doesn't answer). I want my solution to look like this (names changed of course): These three are used by all solutions created under this "family": MyCompany.Extensions MyCompany.MyProject.Tests.Shared MyCompany.MyProject.Scripts This one is the one that makes the solution unique, 123, 124, 125 etc: MyCompany.MyProject.Tests.Unit123 Is it possible to set up a multi-project template that will generate this structure? References: MSDN Create Multi Project Templates

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• IE7 preventDefault() not working on skip links

  - by josh

  I currently have skip links that jump to the div ids and was using e.preventDefault() to stop the url from changing when jumping to the element but in IE7 and IE8 it doesn't work at all using e.preventDefault() and if I take it out the url changes to the div the anchor tag contains reference to. Is their any fix or way around this? Here is the code $('body').delegate('a.skiplink-accessible-text', 'click', function (e) { //e.preventDefault(); if (!$.browser.msie) { e.preventDefault(); } var jumpTo = $(this).attr('href'); $('body').find(jumpTo).attr('tabindex', - 1).focus(); }); EDIT: heres a little jsbin example for testing purposes http://jsbin.com/welcome/20846/edit

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• Pass C++ object to Lua function

  - by peterdemin

  Hello there. I have a C++ project, where 1 method of a 1 class changes very often. So I want to take that code from C++ to Lua. Note, I'm novice to Lua. The whole task: Bind some class methods to Lua state machine; Pass reference to class object to a function, written in Lua; Operate with passed C++ object in Lua function. I've found how to make first step with Lunar, and can't cope with second and third. I can't use SWIG and boost.

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• JQuery selectors select from an html object other than from document root?

  - by orangebrainer

  jQuery selectors select from the document. How do I select from somewhere else other than root? Say I want to select some children from an html object. For this function dothis(obj) { $j("#tabs").removeClass(); $j("#tabs>ul").removeClass(); $j("#tabs>ul>li>a").each(function() { var tabNum = $j(this).attr("href").replace("#", ""); var tabContent = $j("div[id=" + tabNum + "]"); tabContent.removeClass(); $(tabContent).before("<br><h1>" +$j(this).text() + "</h1>\n" ); }); $j("#tabs>ul").each(function() { $j(this).empty();//remove Ul links on top }); } I want to reference the selectors from an html Object (obj) i passed into as argument, instead of selecting from document. Sorry I'm pretty new to jQuery.

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• Android App Support Options

  - by Pughjl

  I've got a free app I'm planning on submitting to the marketplace. Looking over the submission form I see they expect a web site or email for support. Users?! I've got to worry about users if I submit an app? I suppose I would like to get some abuse from users, but I don't want to go broke doing it. So what are my options? I have a web site--I suppose I could install forum software on it--that sounds like a lot of work though. Some apps reference a blogspot page--or I could use my Word Press site. They seems a bit disorganized for getting user feedback though.

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• JavaScript prototype(ing) question

  - by OneNerd

  Trying to grasp Prototyping in Javascript. Trying to create my own namespace to extend the String object in JavaScript. Here is what I have so far (a snippet): var ns { alert: function() { alert (this); } } String.prototype.$ns = ns; As you can see, I am trying to place what will be a series of functions into the ns namespace. So I can execute a command like this: "hello world".$ns.alert(); But the problem is, the this doesn't seem to reference the text being sent (in this case, "hello world"). What I get is an alert box with the following: [object Object] Not having a full grasp of the object-oriented nature of JavaScript, I am at a loss, but I am guessing I am missing something simple. Does anyone know how to achieve this? Thanks -

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• Changing the context of a self-executing function

  - by TaylorMac

  This code is copied directly from: http://www.bennadel.com/blog/2264-Changing-The-Execution-Context-Of-Your-Self-Executing-Function-Blocks-In-JavaScript.htm // Set the singleton value to the return value of the self- // executing function block. var singleton = (function(){ // Declare a private variable. var message = "Stop playing with your context!"; this.getMessage = function(){ return( message ); }; // Return this object reference. return( this ); }).call( {} ); // alert the singleton message. alert( "Message:", singleton.getMessage()); ?My thought is that I can use this to better contain the variables and functions in my programs. However, when I try to run the code in a JSfiddle: http://jsfiddle.net/xSKHh/ It does not return the message. What am I missing?

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• Handling orientation changes yourself

  - by synic

  From the documentation regarding the android:configChanges='orientation' attribute of the activity tag in the manifest: Note: Using this attribute should be avoided and used only as a last-resort. Please read Handling Runtime Changes for more information about how to properly handle a restart due to a configuration change. Why does it say this? In the case of threads and networking requests via a service API library, a request could be made with a reference to the original Activity, and then an orientation change could occur, leaving the thread pointing to the old Activity. While this can be fixed, it's tedious and ugly compared to just handling the configuration changes yourself. Why should it be avoided?

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• C++ - How to call a member function for an inherited object.

  - by Francisco P.

  Hello! I have a few classes (heat, gas, contact, pressure) inheriting from a main one (sensor). I have a need to store them in a vector<Sensor *> (part of the specification). At some point in time, I need to call a function that indiscriminately stores those Sensor *. (also part of the specification, not open for discussion) Something like this: for(size_t i = 0; i < Sensors.size(); ++i) Sensors[i]->storeSensor(os) //os is an ofstream kind of object, passed onwards by reference Where and how shall storeSensor be defined? Is there any simple way to do this or will I need to disregard the specification? Mind you, I'm a beginner! Thanks for your time!

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• how to use constants in SQL CREATE TABLE?

  - by kchiu

  Hi, I have 3 SQL tables, defined as follows: CREATE TABLE organs( abbreviation VARCHAR(16), -- ... other stuff ); CREATE TABLE blocks( abbreviation VARCHAR(16), -- ... other stuff ); CREATE TABLE slides( title VARCHAR(16), -- ... other stuff ); The 3 fields above all use VARCHAR(16) because they're related and have the same length restriction. Is there a (preferably portable) way to put '16' into a constant / variable and reference that instead in CREATE TABLE? eg. something like this would be nice: CREATE TABLE slides( title VARCHAR(MAX_TITLE_LENGTH), -- ... other stuff ); I'm using PostgreSQL 8.4. thanks a lot, and Happy New Year! cheers.

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