On Tuesday, 30 May 2017 at 13:45:07 UTC, Rene Zwanenburg wrote:
On Tuesday, 30 May 2017 at 11:34:52 UTC, ketmar wrote:
If malloc were marked as pure, wouldn't that mean it must
return the same pointer every time you call it with the same
size?
of course. but D "pure" is not what other world knows as
"pure". we love to mess with words.
Well, there's the ability to modify non-const reference
parameters from a pure function, but that's not applicable to
malloc. Are there any other special rules?
The rules[0] are:
0) Can't call functions not marked pure.
1) Can't touch anything mutable that's not explicitly passed to
the pure function.
1b) Except GC internal state - i.e. memory can be allocated via
the GC.
1c) And floating-point exception flags and modes.
2) Can't do I/O (can be seen as a special case of 1 and 0).
There's a few more details, but that's the important stuff.
For a good article on the subject, I recommend David Nadlinger's
Purity in D:
http://klickverbot.at/blog/2012/05/purity-in-d/
[0]: https://dlang.org/spec/function.html#pure-functions
