determine passed key and value types

[Eric Brown]

Is there a way, possibly using reflection, to pass a generic map reference to a function... and for that function to determine the key and value types of that map (without it being specified in the parameters)?

[Tim K]

Something like this?
https://play.golang.org/p/Rit2Vlm9Lh

[Eric Brown]

Man, still learning goLang... and didn't realize this would be that simple.  I highly appreciate your help! 

[Eric Brown]

One last question:  since maps can not be accessed concurrently without a panic, if I attempt to use reflect on it while it's in use somewhere else being written to... will this cause an issue?

On Wednesday, May 25, 2016 at 2:33:53 PM UTC-5, Tim K wrote:

[Roberto Zanotto]

Depends what you are doing with reflection. If you are updating keyvals concurrently, it's a problem.

If you take the reflect.Type value (with reflect.TypeOf(m)), then you can inspect it however you want while the map is being modified.

[Eric Brown]

I'm just inspecting it, so nothing is being modified.  Appreciate your response, Roberto.

[keith....@gmail.com]

You can only access the type safely.  If another goroutine is writing to the map both map reads and writes (reflect or otherwise) are unsafe.

Comparison against nil would also be ok.

[Roberto Zanotto]

Yeah, totally, I'm afraid I didn't make it clear enough.
When you call reflect.TypeOf(m) you get some read-only data structure (an interface, actually) that represents the map's type,

but is not tied to the map itself (it's allocated separately from the map value).