On 11/20/14 7:28 AM, anonymous wrote:
On Thursday, 20 November 2014 at 09:20:34 UTC, Ali Çehreli wrote:
Judging from the name init(), I don't think you need ref anyway.
thanks for the explanation. I can't remove the ref because it is
Main.init in gtkd.
A simple solution is init(args)
I just tried to remove a non-GTK argument (a filename) via slicing. This
is not necessary at all...
To further explain:
The only reason you would need to pass a string[] by ref is if you
wanted to modify the order/size of the array. A string[]'s data is
already passed by reference, so there is no need to ref it otherwise.
What I am guessing gtkd does, is that it processes GTK-specific
parameters from the argument string array, then *removes* those from the
arguments.
If you did *not* pass by reference, these modifications would be corrupt
when you looked at the original.
This is best illustrated by an example:
void foo()(auto ref string[] x)
{
// remove all blanks
size_t i, j;
for(i = 0, j = 0; i < x.length; ++i)
{
if(x[i].length)
x[j++] = x[i];
}
x.length = j;
}
void main()
{
auto arr = ["a", "b", null, "c", "d"];
foo(arr[0..$]); // pass by value
assert(arr == ["a", "b", "c", "d", "d"]); // oops, extra "d"
arr = ["a", "b", null, "c", "d"];
foo(arr); // now by reference
assert(arr == ["a", "b", "c", "d"]);
}
So the compiler is saving you from a mistake :)
-Steve
