On 4/23/2012 19:01, Paul Rubin wrote:
Kiuhnm<kiuhnm03.4t.yahoo.it> writes:
I can't think of a single case where 'is' is ill-defined.
If I can't predict the output of
print (20+30 is 30+20) # check whether addition is commutative
print (20*30 is 30*20) # check whether multiplication is commutative
by just reading the language definition and the code, I'd have to say
"is" is ill-defined.
Counterexample:
import datetime
print(datetime.datetime.now())
You're blaming 'is' for revealing what's really going on. 'is' is
/not/ implementation-dependent. It's /what's going on/ that's
implementation-dependent.
"a is b" is true iff 'a' and 'b' are the same object. Why should 'is'
lie to the user?
Whether a and b are the same object is implementation-dependent.
My point exactly.
Kiuhnm
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