Why Can\'t We Take the Address of Map Values in Go?

Taking Addresses of Map Values in Go

Why does Go prevent taking the address of map values, unlike slice elements? This topic has been raised previously, but the accepted answer, stating that map values aren't backed by arrays like slices, doesn't seem sufficient.

Reconciling Common Assumptions

It's a misconception that numeric map values can be modified in place and that maps have fixed memory locations like slices. Using compound operators like or = for numeric map values effectively performs an assignment of the modified result, rather than directly modifying the map value.

Additionally, despite maps being backed by bucket structures, these buckets are dynamic and can be reorganized as map entries are modified. Therefore, map values do not have fixed memory locations like slice elements.

Conclusion

The inability to take the address of map values in Go stems from the dynamic nature of map buckets. As map entries are created, updated, or deleted, the bucket structure undergoes constant reorganization. This dynamic behavior prevents fixed memory locations for map values, making it impractical to allow address-taking and subsequent modifications. Instead, Go provides methods for indirectly modifying map values by retrieving, modifying, then assigning the updated value back to the map.

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