[gambit-list] Question about |##still-copy| and a |##still?| typechecker

Phillip Suero philsuero at gmail.com
Mon Oct 12 09:30:11 EDT 2020

Dear Marc,

I see in https://github.com/gambit/gambit/blob/master/lib/mem.c#L1621-L1636
that actually ___alloc_scmobj is a wrapper for ___alloc_scmobj_still, great
that clarifies that aspect.

Just curious, when ___ps == NULL it has custom behavior (specifically it
will wrap to ___alloc_scmobj_perm instead). In what situation would ___ps
ever be NULL?


On Mon, Oct 12, 2020 at 10:01 AM Phillip Suero <philsuero at gmail.com> wrote:

> Dear Marc,
> I am sending over an u8vector from the Scheme world to the C world.
> Of course the u8vector must be still, so that its heap allocated object's
> memory address is not moved by Gambit's memory system.
> To get clear on this topic, I have three quick questions for you:
> (1) I see there's the function |##still-copy| in Gambit's runtime.
> Browsing its code I don't see the keyword ___STILL mentioned anywhere in
> it. How does it get the ___STILL property, is that an implicit argument to
> ___alloc_scmobj ?
> (2) Is |##still-copy| a "universal copier" of any heap allocated object,
> into an equivalent of itself that is ___STILL, so I can use it for, say,
> u32vector, floating point number, complex number, string, Scheme struct?
> (3) Is there any checker in Gambit's runtime, e.g. a |##still?|, whereby I
> can check if a heap allocated object is ___STILL already?
> Your clarification is much appreciated, thanks!
> Phil
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