Black Hole update for both branches: cond-expand, Scheme's correspondent to C's ifdef, has been implemented in both branches, and 'black-hole is added to ##cond-expand-features , thus making code compat to Vanilla Gambit and Black Hole.
Code example: (cond-expand (black-hole 'code-for-black-hole-here) (else 'code-for-vanilla-gambit-here))
Execution example: $ *bsc*
*(cond-expand*
* (black-hole* * 'code-for-black-hole-here)* * (else* * 'code-for-vanilla-gambit-here))* code-for-black-hole-here
*,q*
$ *gsc* Gambit v4.6.2
*(cond-expand*
* (black-hole* * 'code-for-black-hole-here)* * (else* * 'code-for-vanilla-gambit-here))* code-for-vanilla-gambit-here
For a practical use example, see row 73 - 92 at https://github.com/m-i-k-a-e-l/gambit-unicode/blob/master/unicode.scm .
Alvaro also made a nice --cond-expand-features=feature1:feature2 option to the syntactictower branch's bh tool. The is no action to move it to the main repo currently but can be found at https://github.com/alvatarc/blackhole/commit/d382bd615df996c6deddf4579eb8cfb... and https://github.com/alvatarc/blackhole/commit/c342963f65c383f5667efb5090ebed2... .
Brgds, Mikael