On Wednesday, 16 April 2014 at 19:44:19 UTC, Peter Alexander
wrote:
On Tuesday, 15 April 2014 at 17:01:38 UTC, Walter Bright wrote:
http://wiki.dlang.org/DIP60
Start on implementation:
https://github.com/D-Programming-Language/dmd/pull/3455
Some initial thoughts:
* Is it perhaps too early to introduce this? We don't have
allocators yet, so it can be quite hard to avoid the GC in some
situations.
* Many Phobos functions use 'text' and 'format' in asserts.
What should be done about those?
As a rule of thumb, format and text should *already* be avoided
altogether in (non-static) asserts, as they can throw exceptions,
preventing a function from being @nothrow. For example, sort:
https://github.com/D-Programming-Language/phobos/pull/2075/files#diff-ff74a46362b5953e8c88120e2490f839R9344
That said, the issue remains relevant for @nogc. Not only the
exception itself, but also for the ".msg" field. How do we
allocate it? Who cleans it up? Does the catcher have to do it?
Can the catcher know he has to do it?
* Does @nogc => nothrow? If I'm not mistaken, throw must
through a GC-allocated Throwable.
Even then, what about asserts? Well, I guess it's OK if Errors
leak, since you are supposed to terminate shortly afterwards.
* If the above is true, does that mean exceptions cannot be
used at all in @nogc code?
* I worry about the number of attributes being added. Where do
we draw the line? Are we going to add every attribute that
someone finds a use for? @logicalconst @nonrecursive
@nonreentrant @guaranteedtermination @neverreturns
I like the concept of having an "@everything" attribute. It
"future proofs" code (in a way, if you are also fine with it
potentially breaking). Also, it is often easier (I think) to not
think in terms of "what guarantees does my function provide", but
rather "what guarantees does my function *not* provide"? EG:
void myFun(int* p) @everyting impure;
My function is safe, nothrow, nogc etc... except pure.
BUT, I think this should be the subject of another thread. Let's
focus on @nogc.
