On Tuesday, 1 August 2017 at 21:59:46 UTC, Steven Schveighoffer
wrote:
On 8/1/17 5:54 PM, Moritz Maxeiner wrote:
On Tuesday, 1 August 2017 at 20:39:35 UTC, Marco Leise wrote:
Am Tue, 1 Aug 2017 10:50:59 -0700
schrieb "H. S. Teoh via Digitalmars-d"
<digitalmars-d@puremagic.com>:
On Tue, Aug 01, 2017 at 05:12:38PM +0000, w0rp via
Digitalmars-d wrote:
> Direct OS function calls should probably all be treated as
> >
unsafe, except for rare cases where the behaviour is very >
well defined in standards and in actual implementations to >
be safe. The way to get safe functions for OS functionality
> is to write wrapper functions in D which prohibit unsafe >
calls.
+1.
I think I got it now!
size_t strlen_safe(in char[] str) @trusted
{
foreach (c; str)
if (!c)
return strlen(str.ptr);
return str.length;
}
:o)
I know this is in jest, but since `strlen`'s interface is
inherently unsafe, yes, the only way to make calling it @safe
happens to also solve what `strlen` is supposed to solve.
To me the consequence of this would be to not use `strlen` (or
any other C function where checking the arguments for @safety
solves a superset of what the C function solves) from D.
I don't think this applies to most OS functions, though, just
to (OS independent) libc functions.
I think it goes without saying that some functions just
shouldn't be marked @safe or @trusted. strlen is one of those.
Of course, though I think this (sub) context was more about
writing @safe D wrappers for @system C functions than about which
C functions to mark as @trusted/@safe. `strnlen` shouldn't be
marked @safe/@trusted, either, but writing a @safe D wrapper for
it doesn't involve doing in D what `strnlen` is supposed to do:
---
size_t strnlen_safe(in char[] str)
{
return strnlen(&str[0], str.length);
}
---
Not that there's much of a reason to do so, anyway, when the D
idiomatic way is just a Phobos away:
---
import std.algorithm;
// I probably wouldn't even define this but use the body as is
auto strnlen_safe(in char[] str)
{
return countUntil(cast(ubyte[]) str, '\0');
}
---
