Return value to QList

[lyucs]

I have a method that returns a QList<int>.

some possibilities:
- QList is returned filled with ints. OK.
- QList returns empty, but because no ints were put in it.

but the method might result in error, and I have to return it nonetheless.
right now, I'm returning a empty QList, but its no good, since a empty QList is possible to happen without error.

I tryed returning 'NULL', but C++ won't let me.
I thought of returning a QList with the first element set to -1, but that's lame.

What can I return instead?
I'd rather not use Exceptions...

thankyou

[jano_alex_es]

think on an impossible value and add it to the list. If the list has only that value, it's like empty.

[Boron]

What about a "bool* ok" function argument?

[spawn9997]

IF you want to test for NULL then you might try returning a QList<int> *.


jw
sw developer

[lyucs]

think on an impossible value and add it to the list. If the list has only that value, it's like empty.
that's what I thought when I said about returning the first element set as -1... but, that's so... not elegant. :p


What about a "bool* ok" function argument?
I can't change any arguments, but maybe I can use that sugestion somewhere else. thanks



IF you want to test for NULL then you might try returning a QList<int> *.
if you meant

return QList<int> *;
that doesn't work. I've got nooo idea why.

thank you all, I think I'll have to rely in 'not elegant' methods XD

[Lykurg]

The "bool *ok" solution is the best. If you can't alter the arguments but you can alter the returned value you can use
QPair<bool, QList<int> > returnListFunction() {}

[wysota]

What can I return instead?

You can return an empty list and besides that have a "lastError" method in your class to determine if the last call was successful or not. Qt uses this approach in many places as an alternative to exceptions.

[john_god]

I use a public bool variable in the class, than, set it in the beginning of the method and change it if the error occur. After calling the method, I check the flag value.