05.07.2012 9:54, lijie пишет:
Hi,
My test code:
import std.stdio;
void main() {
void delegate()[] functions;
foreach (i; 0 .. 5) {
functions ~= {
printf("%d\n", i);
};
}
foreach (func; functions) {
func();
}
}
output:
5
5
5
5
5
This program behaves as expected. Just like C# program that will give
the same output:
---
delegate void MyFunc();
class Program
{
static void Main()
{
var funcs = new MyFunc[5];
for (int i = 0; i < funcs.Length; ++i)
funcs[i] = new MyFunc(() => System.Console.WriteLine(i));
foreach (var f in funcs)
f();
}
}
---
because "i" is the same for every iteration. Different situation is for
such C# loop:
---
for (int i = 0; i < funcs.Length; ++i)
{
int t = i;
funcs[i] = new MyFunc(() => System.Console.WriteLine(t));
}
---
where "t" is local for scope. Here C# behaves correctly, but D doesn't.
This D loop
---
foreach(i; 0 .. 5) {
int t = i;
functions ~= { printf("%d\n", t); };
}
---
prints "4" five times. It's Issue 2043:
http://d.puremagic.com/issues/show_bug.cgi?id=2043
I'm not posting workaround here because bearophile already did it.
--
Денис В. Шеломовский
Denis V. Shelomovskij
