On 20/08/2012 17:04, Gabriel Dos Reis wrote:
On Mon, Aug 20, 2012 at 10:27 AM, David Matthews
<[email protected]> wrote:
On 20/08/2012 15:28, Pierre-Alain Bourdil wrote:
In ForeignTest, the vol2tree method use fromClong to differentiate
between NullTree, or Tree. My union, is made of 2 variants : a struct
pointer and a int64_t . I can't figure out how to decide if a given
vol is a pointer or an int64_t. is there a solution ? The inverse
conversion is pretty forward
It's difficult to know what to do if you can't tell whether you have a
number or the pointer to something. Are you actually returning these sort
of values from your C code to ML? If not you can just use a dummy function
that raises an exception in the conversion from a vol to the ML datatype.
David
I suspect Pierre-Alain is implicitly assuming that somehow PolyML uses
some form of low bits tag to differentiate whether an integer
bit-pattern (e.g. a
value of type intptr_t) is either a vol or an int64_t. I suspect the
answer is no.
Perhaps it would help if we could see the definition of the union type in C.
David
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