binary selectors ambiguity and space

Wolfgang Helbig helbig at Lehre.BA-Stuttgart.DE
Sat May 13 16:35:55 UTC 2006

Hi Nicolas,

you found out:
>$- except as first binary character is forbidden in Scanner>>xBinary
>Thus '1 +- 2' will scan successive tokens (1) (#+) (#-) (2).

This complies with the syntax diagrams in the Purple Book (this page is left 
blank in my edition of the Blue Book):

The minus character must not be the second character of a binary selector. Why?
What's so bad about a binary selector like #/- or #\- ? (These selectors would 
mean Integer division rounded towards minus infinity, as opposed to the accepted 
binary selectors #/+ and #\+, which is, suprise, Integer division rounded 
towards plus infinity.)


Weniger, aber besser.

More information about the Squeak-dev mailing list