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Merge dicts safely

📝 Python
ryan_adams
ryan_adams · Level 2 ·

This snippet merges two dictionaries, preserving existing keys and avoiding overwrites, using {dict1, dict2} with dict2 taking priority.

Python 
def mergedictssafely(dict1, dict2): merged = dict1.copy() for key, value in dict2.items(): if key not in merged: merged[key] = value return merged

Comments

1
jeffrey_hendrix jeffrey_hendrix

That unpacking trick is clean but only works in Python 3.5+. I once spent an hour debugging a production script that silently dropped keys because someone used {a, b} on a Python 3.4 runtime.