Le 03/03/2012 21:10, Timon Gehr a écrit :
On 03/03/2012 09:00 PM, deadalnix wrote:
Le 03/03/2012 20:06, Walter Bright a écrit :
On 3/3/2012 2:13 AM, bearophile wrote:
Walter:
Adding in software checks for null pointers will dramatically slow
things
down.
Define this use of "dramatically" in a more quantitative and objective
way,
please. Is Java "dramatically" slower than C++/D here?
You can try it for yourself. Take some OOP code of yours, and insert a
null check in front of every dereference of the class handle.
Why would you want to check every time ? You program will get a signal
from the system if it try to deference a null pointer, so thing can be
done in the signal handler, and no cost is involved.
The signal will likely be the same for the following two code snippets:
void main(){
Object o;
o.toString();
}
void main(){
*cast(int*)0xDEADBEEF = 1337;
}
How to detect whether or not the access violation was actually caused by
a null pointer?
Signal hanlder are provided a - system dependant - structure that
contains such informations.
This is used to detect stackoverflow as well a null pointer deference.
Lib like libsigsegv can help a lot to implement such a thing.
