[Python-Dev] PySequence_Concat for dicts (original) (raw)

Raymond Hettinger python at rcn.com
Sat Jan 12 02:21:16 CET 2008

I wasn't suggesting that the result of concatenation would be a chained table, rather that it would perform the equivalent of an update and return the new dict (the same way extend works for lists)

When does it come-up that you want a third summed dict while keeping the two originals around unchanged? Does it matter that the addition is non-commutative? Would a + b + c produce an intermediate a/b combo and then another new object for a/b/c so that the entries in a get copied twice and memory usage has to hold a, b, a/b, c, and a/b/c in memory all at the same time?
What are the use cases?

FWIW, the Py3.0 API for dicts will support some set-like operations. Perhaps, that fits the bill.

Raymond

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