[Issue 2443] New: opApply should allow delegates that are not ref if it makes no sense
d-bugmail at puremagic.com
d-bugmail at puremagic.com
Thu Nov 6 07:44:45 PST 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2443
Summary: opApply should allow delegates that are not ref if it
makes no sense
Product: D
Version: 2.019
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P2
Component: DMD
AssignedTo: bugzilla at digitalmars.com
ReportedBy: schveiguy at yahoo.com
Currently, builtin arrays enjoy the restriction that you cannot ref the index
parameter when doing a foreach:
int main(string[] args)
{
foreach(ref i, ref s; args) // Error: foreach: key cannot be out or ref
{ }
}
But when trying to do something similar on a struct, the compiler cannot
resolve the opApply:
struct S
{
int[] arr;
int opApply(int delegate(int i, ref int v) dg)
{
int result = 0;
foreach(i, ref x; arr)
{
if((result = dg(i, x)) != 0)
break;
}
return result;
}
}
void main()
{
S s;
foreach(i, ref v; s)
{}
}
emits:
testit.d(32): function testit.S.opApply (int delegate(int i, ref int v) dg)
does not match parameter types (int delegate(ref int __applyArg0, ref int v))
testit.d(32): Error: cannot implicitly convert expression (__foreachbody1) of
type int delegate(ref int __applyArg0, ref int v) to int delegate(int i, ref
int v)
This has implications for const as well, because it would make sense in S above
to have an opApply WITHOUT a ref int for the value in the case of a const S.
--
More information about the Digitalmars-d-bugs
mailing list