On Monday, 8 August 2022 at 19:33:14 UTC, Steven Schveighoffer
wrote:
There's nothing clever. If you want to access C globals, you
should use `__gshared`, because that's what it is. Using
`shared`, isn't going to save you at all.
Yes, using `shared` does save you.
C might not have a `shared` qualifier, but C programmers still
have to think about thread-safety. Calling a C function or
accessing a C global always comes with some (possibly implied)
contract on how to do it safely from multiple threads (the
contract might be: "don't").
`shared` (with `-preview=nosharedaccess`) forces you to think
about what the contract is. `__gshared` doesn't.
[...]
Using `__gshared` to share data with C is as safe as using
`-boundscheck=on` and sending the array into C which has no
such restrictions.
No it's not. C always being unsafe is true but irrelevant. The
point is what you can/can't do on the D side.
`-boundscheck=on` - Can't easily mess up on the D side. C side
can still mess up.
`-boundscheck=off` - Can easily mess up on the D side.
`shared` - Can't easily mess up on the D side. C side can still
mess up.
`__gshared` - Can easily mess up on the D side.
