maemo.org - Talk - View Single Post - QDataStream ad QList problem!

	Venemo	2010-06-03 , 23:02
	Posts: 1,296 \| Thanked: 1,773 times \| Joined on Aug 2009 @ Budapest, Hungary	#12

Originally Posted by saxen

ok with 2) i've solve problem with >> operator...but anything else is working xD

i'm sure is a reference/pointer stuff. i mean, i'm adding to my QList<Service> a reference Service service in a method called "addItems". Will it be this reference deleted once the addItems is over even if it's now linked in my list?!

so should i use Service * service = new Service() and then add with list->append(*service) ?!

No. Don't get confused with this.
When you append an item to a collection in such a way, or assign it to a variable, it gets copied. (Its copy constructor or operator= gets called.)

Eg.

Code:

MyClass item; //creating a new item
item.stuff = 42;
MyClass item2 = item; //behind the scenes, item2 copies item
item.stuff = 8; //this line doesn't change item2

Note that by default, the MyClass type can't be copied.
You need to tell HOW it is gonna be copied.
That's why there is a copy constructor or an operator=.

Basically,

Code:

item2 = item;

is the same as

Code:

item2.operator=(item);

and only works if there is a

Code:

MyClass::operator=(const MyClass& other) { ... }

method in your class.

And

Code:

MyClass item2 = item;

is the same as

Code:

MyClass item2(item);

and only works if there is a

Code:

MyClass::MyClass(const MyClass& other) { ... }

constructor in your code.

__________________
You should follow me on Twitter!

Apps: Puzzle Master, IRC Chatter for Harmattan, IRC for Sailfish

Last edited by Venemo; 2010-06-03 at 23:06.

Quote & Reply |

The Following User Says Thank You to Venemo For This Useful Post:
saxen