[Python-ideas] Dict joining using + and +=

[Rémi Lapeyre]

I’m having issues to understand the semantics of d1 + d2.

I think mappings are more complicated than sequences it some things
seems not obvious to me.

What would be OrderedDict1 + OrderedDict2, in which positions would be
the resulting keys, which value would be used if the same key is
present in both?

What would be defaultdict1 + defaultdict2?

It seems to me that subclasses of dict are complex mappings for which
« merging » may be less obvious than for sequences.