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  • How to properly assign a value to the member of a struct that has a class data type?

    - by sasayins
    Hi, Please kindly see below for the codes. Its compiling successfully but the expected result is not working. Im very confused because my initialization of the array is valid, //cbar.h class CBar { public: class CFoo { public: CFoo( int v ) : m_val = v {} int GetVal() { return m_val; } private: int m_val; }; public: static const CFoo foo1; static const CFoo foo2; public: CBar( CFoo foo ) m_barval( foo.GetVal() ){} int GetFooVal() { return m_barval; } private: int m_barval; }; //cbar.cpp const CBar::CFoo foo1 = CBar::CFoo(2); const CBar::CFoo foo2 = CBar::CFoo(3); //main.cpp struct St { CBar::CFoo foo; }; St st[] = { CBar::foo1, CBar::foo2 }; for( int i=0; i<sizeof(st)/sizeof(St); i++ ) { CBar cbar( st[i].foo ); std::cout << cbar.GetFooVal() << std::endl; } But then when I change the St::foo to a pointer. And like assign the address of CBar::foo1 or CBar::foo2, its working, like this, //main.cpp struct St { const CBar::CFoo *foo; }; St st[] = { &CBar::foo1, &CBar::foo2 }; for( int i=0; i<sizeof(st)/sizeof(St); i++ ) { CBar cbar( *st[i].foo ); std::cout << cbar.GetFooVal() << std::endl; } The real problem is. The app should output 2 3 Please advice. Many thanks.

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  • How do I add a function to a specific element type in jQuery?

    - by Chad Johnson
    I can do this jQuery.fn.validate = function(options) { var defaults = { validateOPtions1 : '', validateOPtions2 : '' }; var settings = $.extend({}, defaults, options); return this.each(function() { // you validation code goes here }); }; but that will make validate() available for every element. I could do this to any element: $('some selector').validate(). Is there a way I can make this only available to, say, form elements? eg. $('.mySpecialFormClass').validate()?

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  • Would Python's Twisted library be the best case for an observer type pattern?

    - by beagleguy
    hi all, I'm developing a system where a queue will be filled with millions of items I need a process that reads items from the queue constantly and then sends those items out to registered clients. I'm thinking about using twisted for this, having the queue reader be a twisted server listening on a tcp port then clients can connect on that port and when an item is pulled from the queue the server writes it out to all the clients. Does that sound like something that twisted would be ideal for? Does anyone know of any sample code out there that may do something similar? thanks

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  • How to use a class as the base, but hide the class type publically?

    - by James
    I am currently just exposing the properties through a generic interface e.g. public interface IBaseClass { int ID { get; set; } } internal class MyBaseClass : IBaseClass { public MyBaseClass() { } public int ID { get; set; } } public class MyExposedClass : IBaseClass { private MyBaseClass _base = new MyBaseClass(); public int ID { get { return _base.ID; } set { _base.ID = value; } } } Then in my main application I can do: IBaseClass c = new MyExposedClass(); c.ID = 12345; But can't do: MyBaseClass b = new MyBaseClass(); This is my desired behaviour. However, I was just wondering if this is the correct approach? Or if there was a better way?

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  • Bizarre static_cast trick?

    - by Rob
    While perusing the Qt source code I came across this gem: template <class T> inline T qgraphicsitem_cast(const QGraphicsItem *item) { return int(static_cast<T>(0)->Type) == int(QGraphicsItem::Type) || (item && int(static_cast<T>(0)->Type) == item->type()) ? static_cast<T>(item) : 0; } Notice the static_cast<T>(0)->Type? I've been using C++ for many years but have never seen 0 being used in a static_cast before. What is this code doing and is it safe? Background: If you derive from QGraphicsItem you are meant to declare an unique enum value called Type that and implement a virtual function called type that returns it, e.g.: class Item : public QGraphicsItem { public: enum { Type = MAGIC_NUMBER }; int type() const { return Type; } ... }; You can then do this: QGraphicsItem* item = new Item; ... Item* derivedItem = qgraphicsitem_cast<Item*>(item); This will probably help explain what that static_cast is trying to do.

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  • can I store an id value in array of float type ?

    - by srikanth rongali
    I used, for(id value in values) to get the value from an NSArray. Now I want to store it in 2 dimensional float array[][]. When I try to assign the values to array it is giving error:incompatible types in assignment. I tried to cast the value but I got error: pointer value used where a floating point value was expected. I need to store the values in an 2 dimensional array . How can I make it ? Thank You. @implementation fromFileRead1 NSString *fileNameString; int numberOfEnemies, numberOfValues; -(id)init { if( (self = [super init]) ) { NSString *path = @"/Users/sridhar/Desktop/Projects/exampleOnFile2/enemyDetals.txt"; NSString *contentsOfFile = [[NSString alloc] initWithContentsOfFile:path]; NSArray *lines = [contentsOfFile componentsSeparatedByString:@"\n"]; numberOfEnemies = [lines count]; NSLog(@"The number of Lines: %d", numberOfEnemies); for (id line in lines) { NSLog(@"Line %@", line ); NSString *string1 = line; NSArray *split1 = [string1 componentsSeparatedByString:@","]; numberOfValues = [split1 count]; NSLog(@"The number of values in Row: %d", numberOfValues); for (id value in split1) { NSLog(@"value %@", value); float value1; value1 = [split1 objectAtIndex:2]); NSLog(@"VAlue of Value1 at index 2: %f", value1 ); } } } return self; } @end In enemyDetal.txt I have 1,3,3 2,3,2.8 10,2,1.6

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  • What are the requirements of a collection type when model binding?

    - by Richard Ev
    I have been reviewing model binding with collections, specifically going through this article http://weblogs.asp.net/nmarun/archive/2010/03/13/asp-net-mvc-2-model-binding-for-a-collection.aspx However, the model I would like to use in my code does not implement collections using generic lists. Instead it uses its own collection classes, which inherit from a custom generic collection base class, the declaration of which is public abstract class CollectionBase<T> : IEnumerable<T> The collections in my POSTed action method are all non-null, but contain no elements. Can anyone advise?

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  • Jquery convert string of one type to string array.....

    - by chandru_cp
    Consider a string which is {"Table" : [{"Bird" : "Peacock"}, {"Bird" : "Crow"}]} to this ["Peacock", "Crow"] in jquery... Is this possible? EDIT: I am doing this but didnt work... $(document).ready(function() { var obj = JSON.parse('{"Table" : [{"Bird" : "Peacock"},{"Bird" : "Crow"}]}'); myarray = []; $.each(obj.table, function(i, v) { myarray.push(v.Bird); }); $("#tags").autocomplete(myarray, { width: 138, max: 4, highlight: false, multiple: true, multipleSeparator: " ", scroll: true, scrollHeight: 300 }); });

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  • How do I ensure my abstract class's function can only operate on extenders of the same type as the c

    - by incrediman
    For example, let's say this is my abstract class: abstract class A{ int x; int y; void foo(A fooMe); } ...and B and C are two classes which extend A. What I want is for B to only be able to call foo() on other Bs, and for C to only be able to call foo() on other Cs. But I want this to be out of the hands of the programmer who's extending my A class - that is, I want a way to ensure this functionality within As code alone. What can I do? (If possible) I'd like to avoid any hack or generics solution that's too messy - I still want foo to be able to be called like this, for example: B b=new B(); B bb=new B(); bb.foo(b);

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  • Buffer size: N*sizeof(type) or sizeof(var)? C++

    - by flyout
    I am just starting with cpp and I've been following different examples to learn from them, and I see that buffer size is set in different ways, for example: char buffer[255]; StringCchPrintf(buffer, sizeof(buffer), TEXT("%s"), X); VS char buffer[255]; StringCchPrintf(buffer, 255*sizeof(char), TEXT("%s"), X); Which one is the correct way to use it? I've seen this in other functions like InternetReadFile, ZeroMemory and MultiByteToWideChar.

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  • How do I check the Database type in a Rails Migration?

    - by Shaun F
    I have the following migration and I want to be able to check if the current database related to the environment is a mysql database. If it's mysql then I want to execute the SQL that is specific to the database. How do I go about this? class AddUsersFb < ActiveRecord::Migration def self.up add_column :users, :fb_user_id, :integer add_column :users, :email_hash, :string #if mysql #execute("alter table users modify fb_user_id bigint") end def self.down remove_column :users, :fb_user_id remove_column :users, :email_hash end end

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  • Encoding GBK2312 Condundrum

    - by user792271
    I am an amateur coder and I have a small problem. My goal is to have one text input with two buttons. The first button uses a bit of Javascript called SundayMorning to translate the text (to Chinese) The second button submits the text to a URL. The URl requires that Chinese text be encoded it in GBK2312 character set. I have duct taped together various found code to the result I have now. Due to the finicky behavior of the SundayMorning Javascript, my solution is to have two input boxes, the second of which I will hide. Right now, this doesn't work: I am unable to encode the Chinese in GBK2312, no matter what I try. BONUS CONUNDRUM: The second box copies my input letter by letter as I type, but does not copy the Chinese translation that the Javascript returns. Sorry for my janky amateur code. I defer to those more clever, if you have any kind suggestions. <head> <meta http-equiv="Content-Type" content="text/html; charset=GB2312" /> <script type='text/javascript' Src='https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js'> </script> ///THIS JS TRANSLATES THE TEXT INLINE <script type="text/javascript" src="jquery.sundaymorning.js"> </script> <script type="text/javascript"> $(function() { $('#example3').sundayMorningReset(); $('#example3 input[type=image]').click(function(evt) { $.sundayMorning( $('#example3 input[type=text]').val(),{source:'en', destination:'ZH', menuLeft:evt.pageX, menuTop:evt.pageY},function(response) {$('#example3 input[type=text]').val(response.translation);});});}); </script> /// ///THIS PUTS THE CONTENT OF THE TRANSLATION BOX INTO THE SUBMISSION BOX <script type="text/javascript"> $(document).ready(function(){ var $url = $("#url"); $("#track").keyup(function() { $url.val(this.value);}); $("#track").blur(function() { $url.val(this.value);});}); </script> ///THIS PUTS THE CONTENT OF THE SUBMISSION INSIDE A URL <SCRIPT type="text/javascript"> function goToPage(url) { var initial = "http://example.com/"; var extension = ".html"; document.something.action=initial+url+extension; } </SCRIPT> </head> <body> <div id="featured"> <div id="example3"> <input type="text" name="track" id="track" value="" class="box"onkeydown="javascript:if (event.which || event.keyCode){if ((event.which == 13) || (event.keyCode == 13)) {document.getElementById('mama').click();}};"/> <input type="image" src="http://taobaofieldguide.com/images/orange-translate-button.png" id="searchsubmit" value="Translate" class="btn" /> </div> <FORM name="something" method="post" onsubmit="goToPage(this.url.value);"> <input type="text" id="url";> <INPUT type="submit" id="mama" value="GO" > </FORM> </div> </body>

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  • Is it possible to build this type of program in PHP?

    - by Steven
    I want to build a QA program that will crawl all the pages of a site (all files under a specified domain name), and it will return all external links on the site that doesn't open in a new window (does not have the target="_blank" attribute in the href). I can make a php or javascript to open external links in new windows or to report all problem links that don't open in new windows of a single page (the same page the script is in) but what I want is for the QA tool to go and search all pages of a website and report back to me what it finds. This "spidering" is what I have no idea how to do, and am not sure if it's even possible to do with a language like PHP. If it's possible how can I go about it?

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  • Prevent coersion to a single type in unlist() or c(); passing arguments to wrapper functions

    - by Leo Alekseyev
    Is there a simple way to flatten a list while retaining the original types of list constituents?.. Is there a way to programmatically construct a heterogeneous list?.. For instance, I want to create a simple wrapper for functions like png(filename,width,height) that would take device name, file name, and a list of options. The naive approach would be something like my.wrapper <- function(dev,name,opts) { do.call(dev,c(filename=name,opts)) } or similar code with unlist(list(...)). This doesn't work because opts gets coerced to character, and the resulting call is e.g. png(filename,width="500",height="500"). If there's no straightforward way to create heterogeneous lists like that, is there a standard idiomatic way to splice arguments into functions without naming them explicitly (e.g. do.call(dev,list(filename=name,width=opts["width"]))? -- Edit -- Gavin Simpson answered both questions below in his discussion about constructing wrapper functions. Let me give a summary of the answer to the title question: It is possible to construct a heterogeneous list with c() provided the arguments to c() are lists. To wit: > foo <- c("a","b"); bar <- 1:3 > c(foo,bar) [1] "a" "b" "1" "2" "3" > c(list(foo),list(bar)) [[1]] [1] "a" "b" [[2]] [1] 1 2 3 > c(as.list(foo),as.list(bar)) ## this creates a flattened heterogeneous list [[1]] [1] "a" [[2]] [1] "b" [[3]] [1] 1 [[4]] [1] 2 [[5]] [1] 3

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  • Any way to make a generic List where I can add a type AND a subtype?

    - by user383178
    I understand why I cannot do the following: private class Parent { }; private class Child extends Parent { }; private class GrandChild extends Child { }; public void wontCompile(List<? extends Parent> genericList, Child itemToAdd) { genericList.add(itemToAdd); } My question is there ANY practical way to have a typesafe List where you can call add(E) where E is known to be only a Parent or a Child? I vaguely remember some use of the "|" operator as used for wildcard bounds, but I cannot find it in the spec... Thanks!

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  • How to check if String value is Boolean type in Java?

    - by Ragnar
    I did a little search on this but couldn't find anything useful. The point being that if String value is either "true" or "false" the return value should be true. In every other value it should be false. I tried these: String value = "false"; System.out.println("test1: " + Boolean.parseBoolean(value)); System.out.println("test2: " + Boolean.valueOf(value)); System.out.println("test3: " + Boolean.getBoolean(value)); All functions returned false :(

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  • How to define a new type (class) in Python using C API?

    - by ~mech
    Hi, I am trying to use the Python C API to define a new class inside a module that would expose certain functionality written in C to Python code. I specifically want to have it in the form of a class and not a set of module functions. However, I can't find anything regarding this particular task in the official documentation. The closest I could find is PyClass_New function (in the Python.h header) but it is not mentioned anywhere in the official docs, so I assume it is not supposed to be used. So, what is the proper way to define a new Python class from C code? Thanks.

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  • Is there a jQuery plugin for making a step-by-step type presentation?

    - by Earlz
    Hello, I was making a small thing in HTML and basically I have some "frames" like <div id="frame_1"> ... </div> <div id="frame_2"> ... </div> ... Basically what I want is for only one frame to be visible at one time and to navigate between frames easily with previous and next buttons (navigation by frame number a plus, but not required) Before I set out to write it myself I figured someone had already done it so has it been done?

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