On Thursday, 18 May 2017 at 20:20:47 UTC, Gary Willoughby wrote:
This might be a really silly question but:I've allocated some memory like this (Foo is a struct): this._data = cast(Foo*) calloc(n, Foo.sizeof);How can I then later check that there is a valid Foo at `this._data` or `this._data + n`?
Well... I think the right answer is that everything you do with memory should be very deterministic so you should just know where is what and not have a need to check :).
The only thing that crosses my mind if you really need to check is to make sure you always write some specific big number just before each struct in memory as a flag that what follows is Foo and then you can check if that is set properly. I think you could do this by wrapping Foo in another struct whose first field is immutable long set to some specific value (that isn't zero) :) and then using that struct in place of Foo. Although I am not sure if compiler would optimize away checks if an immutable is equal to its init value...
