On Tuesday, 3 December 2013 at 14:18:35 UTC, John Colvin wrote:
On Tuesday, 3 December 2013 at 13:05:20 UTC, Mike Parker wrote:
On 12/3/2013 9:31 PM, John Colvin wrote:
You should be fine to free in that way as long as you haven't
done
anything crazy like separately static linking libc.
I wouldn't advise this in the general case. When you have
complete end-to-end control, sure. But if, for example, you're
using a dynamic binding to load a shared library, all bets are
off. Most likely on Linux and Mac you'll be fine. But on
Windows, the shared lib could have been compiled with DMC,
GCC, MSVC, or who knows what else.
Fair point.
What I should have said is:
This is fine as long as you know you that both the C code and D
code will be using the same so/dll/dylib C runtime.
It's worth noting that the situation is not specific to D: it's
exactly the same as freeing memory in C that you got from a
library. If they are using different runtimes, or even
different instances of the same runtime, all bets are off. At
best, your memory won't get freed, at worst it will cause
corruption.
As with all C code I can only say I _hope_ I know what I'm doing.
The C code is compiled into a library and linked to the D program
at compile time. It's one executable. So I hope that's fine.
I noticed a strange behavior though. In my C code I had an
uninitialized variable[1], the "int length;" mentioned above.
When I compiled it to a library and linked it with my program,
everything worked fine, the string was allocated correctly and
came out as expected, i.e. the length was calculated correctly
with "length += otherlength;". However, when I moved the same
library to my vibe.d project, compiled and linked, I got a
segmentation fault and the program crashed. It wasn't until then,
that I became aware of uninitialized variable. I think that the
latter behavior is the correct one (segfault > crash). But why
did it work correctly in the other D program, how did the C
variable get initialized?
[1] a D habit not to write "int i = 0;", but just "int i;", being
the spoiled D-brat I am
