[Python-Dev] Dictionary Foolishness?

[Raymond Hettinger]

Have dictionaries support the repetition.
Use the replication factor to provide a hint
as to how large the dictionary is expected
to be.

[0] * n   # allocate an n-length list
{} * n    # allocate an n-element dictionary

If the a list already has k elements, the result
is already n*k long; however, for a dictionary,
since the keys are unique, the result says at n*1.
Hence, the dictionary contents are unaffected
by repetition.  But the n-factor is useful for
eliminating all but one of the re-size operations 
when growing a large dictionary, element by element.

If k > n, then the hint is disregarded since the
number of elements already exceeds the hint.


Raymond Hettinger