Am 16.07.2019 um 21:22 schrieb Seymour J Metz:
Furthermore: the more modern languages like Pascal, C and Java etc.
forbid the use of reserved symbols as variable names. This may be
restrictive, but makes the compilers much much simpler.
The cardinal sin in language design is to make the compiler simpler at the
expense of the user. An enhancement to a language with reserved word can render
a previously valid program invalid. Contrast this with PL/I, where several
times keywords have been added without affecting existing code.
Yes, I agree somehow to that statement ...
since I am working on my version of Stanford Pascal,
I sometimes felt the need for adding new keywords. I always had bad
feelings
when doing this.
The compiler already had OTHERWISE (but no abbreviation to his, obviously),
EXTERNAL and FORTRAN.
I added BREAK, CONTINUE, RETURN, MODULE, LOCAL and STATIC;
this was in the years from 2011 to 2016. No more need since.
Don't confuse this with adding new builtin function, which is much less
critical,
because you always can redefine builtin functions (which are considered
predefined
functions at level 0) with own functions with the same name doing
different things
and having different prototypes at lower levels.
IMO, new keywords are only OK, if they have a sort of well-known meaning,
inherited from other languages.
A big problem with C, IMO, is that it uses "static" for different
purposes where
an additional keyword "local" (as I did it) would have been much better.
Kind regards
Bernd
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
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