Am 11.12.2011 20:35, schrieb Andrei Alexandrescu:
On 12/11/11 12:40 PM, Mafi wrote:
void f(ref const(int)* a, const(int)* b) {a = b; }
void main() {
immutable(int)* a;
auto b = (new int[](5)).ptr;
f(a, b);
//if this compiles I have just assigned a mutable pointer
//to an immutable one
}
immutable(int)* does not convert to immutable(const)*.
Andrei
[assuming you meant ref const(int)*]
But look:
I want a function f(a,b) so that it copies int* b into a. I want this
function to be const correct and not to be a template.
If I'm not mistaken, in the planned D (ie without bugs and with
everything implememnted correctly) there's no way to express such a
function.
I see two solutions:
1. Allow calling void f(ref const(int)* a, const(int)* b) {a = b; }
with immutable parameter a.
2. Allow void f(ref inout(int)* a, inout(int)* b) { a = b; } using my
rule I suggested before.
I think Walter suggests number 1 but as I showed it violates the const
system.
I think allowing inout with ref/out parameters is right even without the
return value being inout. These ref/out parameters are conceptionally
results.
I should also be allowed if delegate/function has a inout parameter. So
void g(inout int a, delegate(inout(int)*)) should be allowed.
This delegate is a callback and it's parameter is conceptionally the
result of this function.
In my opinion we definitly have to change the current strict inout-rule.
Mafi
