Generics will not solve this fully anyway - you’ll still need reflection. Why 
not just return empty if the user doesn’t pass a struct?

> On Jun 24, 2020, at 8:29 AM, Pee Jai <p...@pjebs.com.au> wrote:
> 
> 
> Here is my use case: 
> https://godoc.org/github.com/rocketlaunchr/react#UnmarshalState
> 
> That function has an argument that accepts only a struct. I use the reflect 
> package to iterate over the structs fields (and also to check if it actually 
> is a struct). The function has notapplicability for non-structs.
> 
> Currently I have to notify the user via documentation that only a struct is 
> allowed since the type is officially an `interface{}`. This is very crude.
> 
> If there was a way to add a type constraint for only structs, then I don't 
> need to use documentation, notwithstanding the use of reflect package to 
> iterate over the struct fields.
> 
>> On Wednesday, June 24, 2020 at 10:34:40 AM UTC+10, Ian Lance Taylor wrote:
>> On Mon, Jun 22, 2020 at 7:08 PM Pee Jai <p...@pjebs.com.au> wrote: 
>> > 
>> > I can't find a way to constrain for just structs. I don't want primitives. 
>> 
>> The design draft doesn't provide any mechanism for a type constraint 
>> to match any arbitrary struct type, and not any other kind of type. 
>> 
>> But it's not clear why that would be useful.  The only things you can 
>> do with a value of an arbitrary struct type are things that you can do 
>> with a value of any arbitrary type. 
>> 
>> Ian 
> 
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