Hello,
I would definitely use *func Iter(ctx, data) iter.Seq2[T, error]*
Because its standard and it is easy for the end user to build a bridge to a
scanner like API
such as struct[T any]{ All() iter.Seq[T]; Err() error },
or* anything else*.
Because i have make the *trailing error return* a *first citizen*,
that signature fits straight into my own experiments .
For certain, i would not use func IterWithErr(ctx, data, err *error)
iter.Seq[T]
It data raced the second i tried this approach.
spaghetti for thoughts.
https://go.dev/play/p/55w9IqH0KPQ
Le mardi 3 septembre 2024 à 19:19:31 UTC+2, Christoph Berger a écrit :
> I like this approach.
>
> - bufio.Scanner-style errors are a known pattern from the stdlib
> - The approach keeps the key and value params free for their intended
> use
> - It doesn't require nested iter seqs
> - It is compatible with range loops
>
> Made some sample code as PoC -> https://go.dev/play/p/6qhH6ZN6f0S (Doesn't
> work in the playground due to network restrictions)
>
> On Saturday, August 31, 2024 at 1:38:53 PM UTC+2 gbarr wrote:
>
>> I would likely go with something similar to how you would currently use
>> bufio.Scanner but comine the use of .Scan() and .Text() as Range()
>>
>> ```go
>> iter := rows.Iter(ctx)
>> for obj := iter.Range {
>> // do something with obj
>> }
>> if err := iter.Err(); err != nil {
>> return err
>> }
>> ```
>>
>> Or if rows can only have a single active iterator the there is no need
>> for the iter object
>>
>> ```go
>> for obj := rows.Range(ctx) {
>> // do something with obj
>> }
>> if err := rows.Err(); err != nil {
>> return err
>> }
>> ```
>>
>> Graham.
>>
>> On Thursday, August 29, 2024 at 1:41:47 PM UTC+1 Dmitriy P wrote:
>>
>>> What is the best way to handle errors with iterators?
>>>
>>> How to handle error when we have some object and some type paginates
>>> data (e.g. database/sql.Rows or
>>> https://pkg.go.dev/github.com/aws/aws-sdk-go-v2/service/s3#ListObjectsV2Paginator
>>> )?
>>> I found three, but which should be preferable or maybe I've missed some?
>>>
>>> ```go
>>> type Object smth.Smth
>>> type Paginator interface {
>>> GetNext(ctx) ([]Object, error) // func doing heavy request over internet
>>> HaveNext() bool
>>> }
>>> ```
>>>
>>> ```go
>>> func Iter(ctx, data) iter.Seq2[Object, error]
>>>
>>> for obj, err := Iter(...) {
>>> if err != nil {
>>> return err
>>> }
>>> // do smth with Object
>>> }
>>> ```
>>>
>>> ```go
>>> func IterWithErr(ctx, data, err *error) iter.Seq[Object]
>>>
>>> var err error
>>> for obj := IterWithErr(..., &err) {
>>> // do smth with Object
>>> }
>>> if err != nil {
>>> return err
>>> }
>>> ```
>>>
>>> ```go
>>> func IterOverIter(ctx, data) iter.Seq2[iter.Seq[Object], error]
>>>
>>> for page, err := IterOverIter(...) {
>>> if err != nil {
>>> return err
>>> }
>>> for obj := page(...) {
>>> // do smth with Object
>>> }
>>> }
>>> ```
>>>
>>>
>>>
--
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.
To view this discussion on the web visit
https://groups.google.com/d/msgid/golang-nuts/5e33b29d-ed4e-4399-ad93-d95483d519f0n%40googlegroups.com.
