On Sunday, 12 June 2016 at 18:24:58 UTC, jmh530 wrote:
garbage collected variable and assign it to it. Everything
seems to work fine. I'm just not sure if there are any gotchas
to be aware of.
class Foo
{
int baz = 2;
}
void main()
{
import std.stdio : writeln;
Foo foo;
{
Foo bar = new Foo();
foo = bar;
}
//bar is now out of scope
assert(foo.baz == 2);
}
Everything works fine in your example because 'new' always
allocates on the heap. Anything allocated on the stack is not
guaranteed to be valid after the scope exits:
struct Foo
{
int baz;
~this() { baz = 1; }
}
void main()
{
import std.stdio : writeln;
Foo* foo;
{
Foo bar = Foo(10);
foo = &bar;
}
//bar is now out of scope
assert(foo.baz == 10);
}
Struct constructors are always run when exiting a scope. More
importantly, the pointer to bar is only valid until the stack
address where it lives is overwritten by another stack
allocation. In this example, there's no chance for that to happen
before I access it, but it could happen at any time.
