Much of the stdlib works in the manner I describe. Yes Go allows invocations on
nil interface references, but most implementations will panic.
Multiple Close is almost never a good thing, and most implementations guard
against it.
So in the case where the gerReader() succeeds and getDB() fails, how do you
clean-up (without a bunch of if clauses, so no better then if err != nil). And
what about the cases when the cleanup code returns errors?
> On Jul 8, 2019, at 7:59 AM, Wojciech S. Czarnecki <o...@fairbe.org> wrote:
>
> On Mon, 8 Jul 2019 07:37:20 -0500
> Robert Engels <reng...@ix.netcom.com> wrote:
>
>> This will never work because of dependent resource allocation.
>> And you wouldn’t be able to check resources against nil if they are structs,
>> so you have no way to properly cleanup up.
>> If would quickly degenerate back to if err != nil.
>
> If the functions called in the block follow bad practices -
> yes, then the `check` will be harder[1] to use for them.
>
>> As in
>>
>> check(err!=nil){
>> token, err = getToken()
>> reader,err = getReader(token)
>> db,err = get DB(reader)
>>
>> catch:
>
>> How do you know know which resources need to be closed/cleaned-up
>
> Because I wrote the getToken and getReader and getDB to return zero
> object on err and gave their .Clean() / .Close() methods ability to be invoked
> multiple times ? :)
>
> [1] // make bad implementations usable with check:
>
> token := &tokenType{} // assume a pointer out of your "against nil"
> reader := new(dummy.Reader)
> db := new(mock.DB)
>
> Anyway, your concerns are sound and need (documentation side) attention.
> Thank you.
>
> --
> Wojciech S. Czarnecki
> << ^oo^ >> OHIR-RIPE
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