On 17/04/2008, at 2:46 AM, James Lampert wrote:
Personally, I've always felt that both Niklaus Wirth and Dennis
Ritchie
were full of equine scat on that one: if a language as advanced as
PL/I,
and one as simple as all but the most rudimentary dialects of
BASIC, can
both recognize whether "=" was being used in an assignment context
or an
equality context, then why SHOULD there be separate operators, at
least
for general use?
Can't recall about Pascal but C requires two operators because it
allows assignment IN an equality context (i.e., if ( a = b) which
doesn't behave in the obvious manner). The only reason C can do this
is because it also has the behaviour of 0 is false and anything else
is true. Any language that allows both assignment and equality in the
same statement requires two operators in order to distinguish between
both operations.
I doubt Pascal allowed assignment in a conditional expression and I
think it had two operators simply to "force clarity of intent" on the
programmer.
However, I'm in agreement with you about using separate operators for
assignment and equivalence. Interestingly Rexx uses doubled operators
for 'strict' comparisons. This to me makes sense. Comparing two
values (ignoring leading zeroes, and leading or trailing blanks) is a
different operation from comparing two values EXACTLY. Different
operations require different operators.
There are certain conditions in systems coding where being able to
assign a value in a conditional statement MAY result in code
efficiencies but these are in the minority--and often only in the
mind of the coder. Seems pointless to me to provide language support
for a construct that:
a) is fraught with peril
b) is considered poor practice
c) is rarely used
So says Simon currently involved in getting C code that compiled
cleanly under the 440 C compiler to compile under the new PASE C/C++
compiler. I thought the old C compiler was strict but the new one
seems over the top. The dreaded "CZM0280-Function argument assignment
not allowed" error. It's not my code by the way--all MY stuff
compiles cleanly under both compilers--but more 'open-source' crap
that follows both old-fashioned and poor coding practices "for
portability reasons". Forgive me for appearing cantankerous ...
Regards,
Simon Coulter.
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