Re: bool empty() const for ranges
On 11/26/21 5:44 AM, Salih Dincer wrote:
Hi All;
I have two questions that make each other redundant. Please answer one
of them. I'm implementing ```bool empty() const``` for ranges as below:
```d
bool empty() // const
{
bool result;
if(!head)
{
result = true;
fastRewind();
}
return result; // head ? false : true;
}
```
* Is the const essential for ranges?
No, there is no specification of whether any range methods have to be
const. As Stanislav says, it is only a requirement that subsequent calls
return the same value as long as popFront has not been called.
* Is it possible to rewind the pointer (```Node * head;```) when my head
is empty by the const?
If const is set, then any members are treated as const, and anything
they point to are treated as const. So no.
That being said, if `fastRewind` changes `empty` from true to false, the
method is invalid.
-Steve
Re: bool empty() const for ranges
On Friday, 26 November 2021 at 10:44:10 UTC, Salih Dincer wrote: * Is the const essential for ranges? * Is it possible to rewind the pointer (```Node * head;```) when my head is empty by the const? `empty` is not required to be `const`, but it is required to yield the same result if called multiple times without mutating the range (see https://dlang.org/phobos/std_range_primitives.html#.isInputRange). In other words, you really ought not to mutate the range in implementation of `empty`, or at least not to the extent you seem to want to.
bool empty() const for ranges
Hi All;
I have two questions that make each other redundant. Please
answer one of them. I'm implementing ```bool empty() const``` for
ranges as below:
```d
bool empty() // const
{
bool result;
if(!head)
{
result = true;
fastRewind();
}
return result; // head ? false : true;
}
```
* Is the const essential for ranges?
* Is it possible to rewind the pointer (```Node * head;```) when
my head is empty by the const?
Thanks...
