On Thu, Feb 28, 2019 at 08:59:30PM -0800, Hasan Diwan wrote:
Do we really need a "+" and a "-" operation on dictionaries? [dictinstance.update({k:v}) for k,v in dictinstance.items()] does handle merges already.
I don;t think that does what you intended. That merges dictinstance with itself (a no-op!), but one item at a time, so in the slowest, most inefficient way possible. Writing a comprehension for its side-effects is an anti-pattern that should be avoided. You are creating a (potentially large) list of Nones which has to be created, then garbage collected.
And I'm assuming that "-" should return the difference -- set(d1.keys()) - set(d2.keys()), right?
No. That throws away the values associated with the keys. P.S. As per Guido's ~~command~~ request *wink* I'm writing a PEP for this. I should have a draft ready later this evening. -- Steven