Le 18/06/2012 18:04, Timon Gehr a écrit :
To explain my proposal, I have to make several thing clear first. You
have here 2 things to qualify : the delegate itself, and the hidden
parameter. As type qualifier are transitive in D, qualify the delegate
also transitively qualify the hidden parameter.
The proposal was to use postfix qualifier notation to qualify the hidden
parameter, and qualifier between return type and delegate keyword to
qualify the delegate itself.
Why would the second part of the proposal be necessary?
What do you qualify as the second part ?
My original proposal stated that the type
qualifier before the return type qualify the return type, but this is
another topic.
To make is clearer, some examples :
void delegate() const; // A mutable delegate that use const frame
pointer (all variable accessed throw the frame pointer are made const).
void const delegate(); // A const delegate that use a const frame
pointer (transitivity).
void const delegate() immutable; // A const delegate that use an
immutable frame pointer (delegate can only access immutable data from
the frame pointer).
void immutable delegate() const; // Error, immutable data cannot refers
to const data.
Note that the implicit cast goes the other way around than usual. void
delegate() const can be safely casted to void delegate(), but not the
other way around, as you are allowed to not mutate mutable data, but not
the other way around.
Comments:
1.
struct S{
int x;
void foo()pure{x++;} // ok
}
void main(){
int x;
void foo()pure{x++;} // currently an error
}
The second part should be allowed. It is qualifying foo as 'immutable'
which should fail.
Yes.
2.
int y;
struct S{
int x;
void foo()immutable{y++;} // ok
}
void main(){
void foo()immutable{y++;} // should be allowed
}
The problem is the unfortunate annotation overhead.
And yes. This is another topic, but I think the way to go is inference.
It would be better to have 'nostatic' as the keyword for the
current 'pure' and 'pure' as a shortcut for 'immutable nostatic'.
This would also silence the 'pure is a misnomer' crowd.
I don't really have an opinion on that subject. I understand the keywork
choice can be confusing, but the overall design is really nice.
