Union of dict objects in Python
associative-array, dictionary, idioms, python, set-operations
Solution
This question provides an idiom. You use one of the dicts as keyword arguments to the `dict()` constructor:
dict(y, **x)
Duplicates are resolved in favor of the value in `x`; for example
dict({'a' : 'y[a]'}, **{'a', 'x[a]'}) == {'a' : 'x[a]'}
Problem
How do you calculate the union of two `dict` objects in Python, where a `(key, value)` pair is present in the result iff `key` is `in` either dict (unless there are duplicates)? For example, the union of `{'a' : 0, 'b' : 1}` and `{'c' : 2}` is `{'a' : 0, 'b' : 1, 'c' : 2}`. Preferably you can do this without modifying either input `dict`. Example of where this is useful: Get a dict of all variables currently in scope and their values