On 26/06/2016 08:36, Lawrence D’Oliveiro wrote:
One of Python’s few mistakes was that it copied the C convention of using “=” 
for assignment and “==” for equality comparison.

One of C's many mistakes. Unfortunately C has been very influential.

However, why couldn't Python have used "=" both for assignment, and for equality? Since I understand assignment ops can't appear in expressions.

It should have copied the old convention from Algol-like languages (including 
Pascal), where “:=” was assignment, so “=” could keep a meaning closer to its 
mathematical usage.

(I think Fortran and PL/I also used "=" for assignment. Both were more commercially successful than Algol or Pascal.)

For consider, the C usage isn’t even consistent. What is the “not equal”
> operator? Is it the “not” operator concatenated with the “equal” operator?
> No it’s not! It is “!” followed by “=” (assignment), of all things!

I thought "!" /was/ the logical not operator (with "~" being bitwise not).

> This fits in more with the following pattern:

    A += B <=> A = A + B
    A *= B <=> A = A * B

in other words

    A != B

should be equivalent to

    A = A ! B

Yes, that's an another inconsistency in C. Sometimes "<>" was used for "not equals", or "≠" except there was limited keyboard support for that. ("/=" would have the same problem as "!=")

But again, that doesn't apply in Python as the "!=" in "A != B" can't appear in expressions.

--
Bartc

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