They're the standard forms of doing dict merge in python, and generally the first answer whenever someone asks (both overwrite with right dict key/value on collision, concatenate keys otherwise).
{ * * d1, * * d2} -- unpack the two dicts and feed them both as input to dict comprehension to construct a new dict.
d1.update(d2) does the same merge strategy, but modifying d1 in-place.
Sure, there's five different ways to go about handling collisions, but there's already a well-defined, commonly used methodology, so it's fair to implement syntax sugar for it. It's also not too difficult to understand, and easy to look up (particularly compared to {* * d1,* * d2}).
And I'm not actually aware of any other merge strategy being included in the python stdlib, which implies that this strategy being the best useful default, has been decided long before this operator came into question.
{ * * d1, * * d2} -- unpack the two dicts and feed them both as input to dict comprehension to construct a new dict.
d1.update(d2) does the same merge strategy, but modifying d1 in-place.
Sure, there's five different ways to go about handling collisions, but there's already a well-defined, commonly used methodology, so it's fair to implement syntax sugar for it. It's also not too difficult to understand, and easy to look up (particularly compared to {* * d1,* * d2}).
And I'm not actually aware of any other merge strategy being included in the python stdlib, which implies that this strategy being the best useful default, has been decided long before this operator came into question.