In light of the "Hidden features of..." series of questions, what little-known features of BCPL have become useful to you?
+1
A:
The best "hidden feature" of BCPL is the one I use on my CV - I hide the fact that I know anything about it, and thus avoid all chance of being drafted onto one of those benighted projects that might still contain some BCPL. Also, perfect the automatc response:
"Weird! Is that some kind of Perl stuff?"
when unexpectedly confronted with BCPL code.
anon
2009-06-23 09:48:39
I've occasionally had to explain to recruiters what it was. But it's still in use on at least three sites I've done work for, one of them still running on a 6809 processor. So I don't think it's entirely dead.
paxdiablo
2009-06-23 10:46:02
+1
A:
Curly brackets. Granted, it's not a particularly hidden feature, nor have I used them in BCPL itself; but it did originate in BCPL, and it's the only notable thing about BCPL for the modern programmer.
Colin Pickard
2009-06-23 09:52:21
"Curly brackets" is a misnomer because the brackets weren't. BCPL (at least the incarnations I used) had "LET x() = VALOF $( ... $)" (not a curl in sight).
paxdiablo
2009-06-23 10:47:48
I've never seen the {} variant in BCPL but I wouldn't discount its existence - standards were somewhat less important back then. I know it did have a way of enforcing bracket matching with "$(1 ... $(2 ... $)2 ... $)1" which C/++ still doesn't have although people often use comments - BCPL compilers checked them though to ensure structure was as expected.
paxdiablo
2009-06-23 11:59:48
+2
A:
The best feature I saw (and this was only in a few implementations, not part of the base language from Martin Richards) was the use of "%%" and "%!" (I may have those two characters in the last one around the wrong way - it's been a while).
BCPL provided a dereferencing facility to extract a word from a word address with word offset by doing:
LET x = y!2
which would be similar to y[2] in C.
The byte offset from byte address (%%) and byte offset from word address (%!) allowed much finer-grained control of memory access in the old CPUs (such as the 6800 and 6809) where BCPL was mostly used.
paxdiablo
2009-06-23 11:21:09