What is the intended use-case for this? Depending on the purpose, you might have a look at mergo, https://github.com/imdario/mergo as it does something similar, mostly for pulling configuration settings from multiple places and combining them with defaults.
For JSON maps, there is https://github.com/peterbourgon/mergemap , and for simpler situations (i.e. merging JSON structs without merging embedded slices or maps), this solution https://play.golang.org/p/8jlJUbEJKf from rog in this post https://groups.google.com/forum/#!topic/golang-nuts/nLCy75zMlS8. As to the code itself, let's see... I do find it a little odd that when asked to merge A, and B, passed in that order, it returns B, A when both items are ints or strings, but if A is a slice, then B is appended to A's slice. So mergeDataStructures("A", "B") = ["B", "A"], while mergeDataStructures([]interface{}{"A"},"B") = ["A", "B"] Just looks like an accidental flipping of b and a to me, easily fixed. Meanwhile mergeDataStructures("A",[]interface{}{"B"}) panics. (i.e. case string: case []interface{}), and even if that code did work, it only references a, so it would be returning an incomplete result even if it did work. When handed two similar items on the same level - two strings or two ints or an int and a string, it promotes the return object to a slice, whereas when the same key with different values appears in two maps being merged, one overwrites the other instead of being promoted. It can't handle structs apparently at all (just a suggestion: many structs can be JSON marshaled and unmarshaled to an map[string]interface{}, which might let them be incorporated fairly simply). Moving on to the question of elegance: To my knowledge, there is no simpler way in Go to merge two maps other than to iterate over one, settings the keys and values into the other (obviously, the one being iterated over effectively has precedence, overwriting the corresponding values in the other). As to merging slices as you have done, well, that rather depends on the intended semantics, so I'm not sure you can do it generically without being wrong for at least some cases. After all, a slice in an arbitrary data structure or document might be sorted or unsorted, or it might be being used as a set and so need to reject duplicate items. So while it might need a few cases tweaked, I think in general you have a reasonably workable solution. I do see that this code does not handle hierarchical maps - it assigns all of a's map values to a map, then all of b's to the same map, without regard for whether they are duplicated. Howard -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
