Re: Emacs rewrite in a maintainable language

[David Kastrup]

address@hidden (Taylan Ulrich "Bayırlı/Kammer") writes:

> (The other day I was hit by this issue while working on Guile's C code,
> where I forgot that a scm_blahblah_p predicate will return SCM_FALSE
> which is not 0 thus not false in C.  Like Qnil in Emacs.)

>From src/lisp.h:

/* True, since Qnil's representation is zero.  Every place in the code
   that assumes Qnil is zero should verify (NIL_IS_ZERO), to make it easy
   to find such assumptions later if we change Qnil to be nonzero.  */
enum { NIL_IS_ZERO = XLI_BUILTIN_LISPSYM (iQnil) == 0 };


-- 
David Kastrup