On 10/29/2013 02:41 PM, David Nadlinger wrote:
> Closures follow the infinite lifetime model – the struct scope is never
> left, if you want.
Agreed but the implicit nature of things is troubling. Imagine that the
program depends on the destructor to be called:
void foo()
{
auto s = S(1);
// ...
}
Later, somebody creates a lambda that silently extends the lifetime of
the stack frame (apparently, infinitely). That may be very surprising.
Aside: Is it still a closure if the lambda does not refer to the stack
frame? If so, it is even worse:
import std.stdio;
struct S
{
int i;
~this() { writeln("dtor"); }
}
void bar()
{}
auto foo()
{
S s = S(1);
return &bar; // <-- all is well, this is not a closure
}
void main()
{
foo()();
}
Imagine someone decides to return a lambda from foo() instead:
auto foo()
{
S s = S(1);
return {}; // <-- Should 's' be immortal now?
}
Too subtle for my taste! :)
> This is not exactly a new scenario, destructors on new'd structs aren't
> called either (unless you manually destroy them).
At least in the case of a new'ed structs I have a convenient way to
destroy them through a pointer. I think in the case of a closure I must
go through hoops to access or save that pointer.
Ali
