Menghan Zheng wrote:
Hello!
Is it assured the following statement is always True?
If it is always True, in which version, python2.x or python3.x?
a = dict()
...
assert(a.values == [a[k] for k in a.keys()])
--> ?
Menghan Zheng
No, it's never true. The assert statement has no return value, neither
True nor False.
But probably you're asking whether the assert statement will succeed
quietly. Again, the answer is no. The first part of the expression is
a built-in method, and the second part is a (possibly-empty) list. So
it'll always throw an AssertionError.
But probably you've got a typo, and meant to include the parentheses:
assert(a.values() == [a[k] for k in a.keys()])
That, I believe, is guaranteed to not fire the assertion in 2.6.
In 2.6, the docs say:
"If items(), keys(), values(), iteritems(), iterkeys(), and itervalues() are
called with no intervening modifications to the dictionary, the lists will
directly correspond"
In 3.x it should fire an assertion error, for any dictionary, because values()
does not return a list, but an iterator for one. However, I don't have the
docs for 3.x handy, I just tried it interactively to confirm my belief.
DaveA
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