On 2 November 2016 at 14:44, Bill Warner <wwar...@gmail.com> wrote:
> Same thing, but keys can be ints. https://play.golang.org/p/2YssTy0dY5
I considered that, but I think that in practice []string is easier to deal
with than []interface{} for a set of indexes, and you'll need to deal with
an error in both cases. In general I'd try to avoid []interface{} unless
the elements really can be anything.
Your code there will panic if there's a slice where you're expecting an object.
I guess it depends how you're intending to use this thing.
I was imagining something like this:
https://play.golang.org/p/gReMKhNe2q
or you could decide to continue with the strict division between
integer and string indexes
and still avoid use of []interface{}:
https://play.golang.org/p/_kPcsf39Mo
>
> On 11/2/16 4:33 AM, roger peppe wrote:
>>
>> I'd suggest something like this:
>>
>> https://play.golang.org/p/w1Vxg6b2Ey
>>
>> Not too much repeated code there, and no need for the reflect package
>> either.
>>
>> cheers,
>> rog.
>>
>> On 1 November 2016 at 17:13, <wwar...@gmail.com> wrote:
>>>
>>> Basically, the idea is: given a json structure, and a list of strings or
>>> integers, treat the list as a path into the structure and return the
>>> value
>>> at that point. There are some things this doesn't do yet, among them:
>>> handle
>>> float values, handle slice indexes that are out of range, handle paths
>>> that
>>> are longer than the struct is deep, etc. But what i've shared runs
>>> against
>>> the sample json.
>>>
>>>
>>> On Tuesday, November 1, 2016 at 1:04:21 PM UTC-4, wwa...@gmail.com wrote:
>>>>
>>>> https://play.golang.org/p/LhOTUuTVqA
>>>>
>>>> On Tuesday, November 1, 2016 at 12:50:09 PM UTC-4, Bill Warner wrote:
>>>>>
>>>>> Yes it's just a fragment. Let me clean it up a bit, then I'll share a
>>>>> playground link.
>>>>>
>>>>> On 11/1/16 12:47 PM, Volker Dobler wrote:
>>>>>
>>>>> Am Dienstag, 1. November 2016 02:07:49 UTC+1 schrieb wwa...@gmail.com:
>>>>>>
>>>>>> Hello all,
>>>>>>
>>>>>> I'm new to Go, and I have a question about identifying types as
>>>>>> they're
>>>>>> encountered in traversing a map[string]interface{}.
>>>>>>
>>>>>> I've ended up with a big sieve of type assertions something like this:
>>>>>>
>>>>>> if mt.Mi, ok = m.(map[string]int); ok {
>>>>>> nval, ok = mt.Mi[mk]
>>>>>> } else if mt.MI, ok = m.(map[string]interface{}); ok {
>>>>>> nval, ok = mt.MI[mk]
>>>>>> } else if mt.Mai, ok = m.(map[string][]int); ok {
>>>>>> nval, ok = mt.Mai[mk]
>>>>>> } else if mt.Mas, ok = m.(map[string][]string); ok {
>>>>>> nval, ok = mt.Mas[mk]
>>>>>> } else if mt.Mmm, ok = m.(map[string]map[string]interface{});
>>>>>> ok
>>>>>> {
>>>>>> nval, ok = mt.Mmm[mk]
>>>>>>
>>>>>> mt here is a struct that performs no work; it just associates a type
>>>>>> to
>>>>>> a name, so that the run-time can see the types of the left and the
>>>>>> right
>>>>>> sides of the assignment and determine if an assignment is possible. I
>>>>>> really
>>>>>> hate looking at that statement, but all my attempts at using
>>>>>> reflection have
>>>>>> failed as the compiler can't allocate with all the possible types that
>>>>>> could
>>>>>> be returned, even though in my application I only want to allocate for
>>>>>> these
>>>>>> five types. So that's my question: Can I DRY this up?
>>>>>
>>>>>
>>>>> The code you showed is basically a noop: If this is going to compile
>>>>> than nval must be of type interface {} and you could replace all this
>>>>> with a simple
>>>>> nval = m
>>>>> You either did not show the last else-block or something is strange
>>>>> here.
>>>>>
>>>>> V.
>>>>>
>>>>>
>>>>>
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