Why list.List?

[funny-falcon]

If you wanted to build “high performance” thing, then why you didn’t implement list by hands? Why you decided to pay overhead of list.Element?

[elliotchance]

This is the first time I've used the container/list package, what is the overhead you're referring to?

[guoruibiao]

it seems that orderedmap is just the wrapper of list.[Element+List]

[algobot76]

The linked list is used to record the insertion order. This is how OrderedDict is implemented in Python as well (see: https://stackoverflow.com/questions/34496582/is-ordereddict-a-tree).

[algobot76]

Also: https://docs.oracle.com/javase/8/docs/api/java/util/LinkedHashMap.html

[funny-falcon]

This is the first time I've used the container/list package, what is the overhead you're referring to?

Separate allocation of list.Element and orderedMapElement. Excess interface pointer from list.Element to orderedMapElement. Excess interface casting for taking orderedMapElement from list.Element.Value.

I'd rather call your implementation “naive” or “lazy” (in term “I was lazy to do low level code by hand, so I took standard library despite it is not for high performance but for lazy programmers”).

[funny-falcon]

I mean, it is not bad to be lazy. Being lazy helps to do less mistakes, and to write more code that has business value.

But “high performance” code in Go could not be written in lazy way.

Just don't call it “high performance”.

[elliotchance]

I take your point. However “high performance” is a relative term, not a quantitative one. If it bothers you, then I’m happy to review a PR with improvements.

[rocaltair]

How can you say it is a orderedmap? with O(1) ?

[elliotchance]

How can you say it is a orderedmap?

It will maintain the keys in the order they were inserted. This is something Go does not do natively with maps.

with O(1) ?

This means operations (Len, Get, Set etc) takes about the same amount of time, regardless of the size of the underlying orderedmap.