On Monday, 23 January 2017 at 22:26:58 UTC, bitwise wrote:
Is it ok to memcpy/memmove a struct in D?
Quote from here:
https://dlang.org/spec/garbage.html
"Do not have pointers in a struct instance that point back to
the same instance. The trouble with this is if the instance
gets moved in memory, the pointer will point back to where it
came from, with likely disastrous results."
This seems to suggests it's ok to move structs around in memory
without calling their postblit...but if this is the case, why
does postblit even exist, if it's not strictly guaranteed to be
called after the struct has been blitted?
You may need the postblit for a *copying* blit. For example, if
a struct does reference counting, the postblit will need to
increment the count for the new copy. It's a slightly different
solution to what C++ solves with copy constructors, assignment
operators, etc. Compared to C++, the D approach is a bit simpler
and trades off a little flexibility for more opportunities for
the compiler to generate efficient code.
Here's the situation in C++, BTW:
http://en.cppreference.com/w/cpp/language/rule_of_three
