On Monday, 8 June 2020 at 09:08:40 UTC, adnan338 wrote:
On Monday, 8 June 2020 at 08:10:19 UTC, Simen Kjærås wrote:
On Monday, 8 June 2020 at 07:35:12 UTC, adnan338 wrote:
Self* searchTree(this Self)(auto in ref T item) const {
if (&this is null)
return null;
if (this.item == item)
return &this;
return (this.item < item) ?
this.right.searchTree(item) :
this.right.searchTree(item);
}
This method is const, which means 'this' is const, while Self
is not. What you're looking for here is inout
(https://dlang.org/spec/function.html#inout-functions):
auto searchTree()(auto in ref T item) inout {
if (&this is null)
return null;
if (this.item == item)
return &this;
return (this.item < item) ?
this.right.searchTree(item) :
this.right.searchTree(item);
}
--
Simen
Thank you. Few followup questions, if you don't mind.
1. What does that blank template parameter mean?
Just forces the function to be a template. The only reason for
this is it's required for auto ref to work, which you may or may
not need on that function.
2. Since `inout` acts as a wildcard for
immutable/const/non-const qualifiers, what should I do to have
the compiler ensure that my method does not mutate a non-const
tree inside the body?
Inside inout functions, `this` is treated as const - any attempt
to modify it should give a compile error. Since D const is
transitive, anything reachable from `this` is also treated as
const. If you're able to mutate a non-const tree inside the
body, there's a bug in the compiler.
--
Simen
