obliterate

[Andrei Alexandrescu]

Hello,


I will soon get to work on typed allocators; I figured there will be 
some issues percolating to untyped allocators that will require design 
changes (hopefully minor).

For starters, I want to define a function that "obliterates" an object, 
i.e. makes it almost surely unusable and not obeying its own invariants. 
At the same time, that state should be entirely reproducible and 
memory-safe.

Here's what I'm thinking. First, obliterate calls the destructor if 
present and then writes the fields as follows:

* unsigned integers: t.max / 2

* signed integers: t.min / 2

* characters: ?

* Pointers and class references: size_t.max - 65_535, i.e. 64K below the 
upper memory limit. On all systems I know it can be safely assumed that 
that area will cause GPF when accessed.

* Arrays: some weird length (like 17), and also starting at size_t.max 
minus the memory occupied by the array.

* floating point numbers: NaN, or some ridiculous value like F.max / 2?



Andrei