On 04/07/2010 10:27 AM, Sean Kelly wrote:
On Apr 7, 2010, at 2:35 AM, Lars Tandle Kyllingstad wrote:
This is mostly out of curiosity, but also relevant for any future
contributions to Phobos:
1. AFAIK, the full interface for the C standard library is in
druntime, specifically the core.stdc package, with OS-dependent
stuff in core.sys. Yet, there still exists an std.c package in
Phobos that contains more or less the same things, and which is
used extensively throughout the rest of the library. Is this
intentional, or am I just seeing the relics of pre-druntime
Phobos?
A bit of both. When std.c was moved it was easier to turn those into
forwarding modules. They remain mostly because some contain
nonstandard declarations and I haven't spent much time working on
core.sys, though perhaps the proper thing in the case of what's left
in std.c is just to declare it privately inside the Phobos module
that needs the routine.
2. Phobos uses functions from the C standard library in favour of
native D implementations in several places. (In light of recent
discussions, std.stdio.File comes quickly to mind.) Is this just a
way of getting things up and running quickly, with the intention of
D-ifying things later, or is it considered a permanent solution?
core.stdc is present as much for users who want to port C code to D
as anything else. But I do see use of standard C routines as an
indicator of where gaps are in Phobos. It's really there "just in
case."
In principle there's nothing wrong with using C functions, but the main
problem is that many of them have problems, and others are unpleasant to
use with D. Examples:
- atoi() is very wrong because not only it doesn't handle errors, it
prevents the caller from diagnosing them.
- Many (strtoul, printf, etc. etc.) use pointers and char*-based
interfaces that are unpleasant and unsafe with D.
- Some (e.g gets, sprintf) are extremely dangerous by design and can't
be made safe.
What remains is a small core of functions such as stat(), which we can
use no problem.
Andrei
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