On Monday, 23 November 2020 at 17:39:09 UTC, Adam D. Ruppe wrote:
On Monday, 23 November 2020 at 17:34:27 UTC, visitor wrote:
Hi all,
I would like to know why in the code below, rgba.ptr[0] is
used instead of rgba[0] and allowing the method to be @safe
The .ptr[0] skips bounds checking.
Since this example is static length with a constant index it
shouldn't matter anyway; the compiler can see it is obviously
in bounds and skip it too.
But if there's any runtime value there's a bounds check with
`foo[0]` and that can be surprisingly expensive in certain
situations. So `foo.ptr[0]` skipping that can give a nice
performance boost.
Just without bounds checking the code is obviously trusting the
programmer... hence @trusted is required instead of safe.
indeed because of the the static length and constant index, it
was puzzling me ...
Thanks Adam for clarification
