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.
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
}
> On Jul 8, 2019, at 7:13 AM, Wojciech S. Czarnecki <o...@fairbe.org> wrote:
>
> The `func check(Condition bool) {}` applies to the block that follows.
> Within this block, every statement that on its left-hand side has any
> variable that is present in the "Condition" expression is supplemented
> with an implicit check of `if Condition { goto catch }` form.
>
> The 'catch:' label can be given explicit, or be assumed implicit at
> last statement of the block.
>
> // Condition is not restricted to `err != nil`.
> // Below snippet will `break` if x was < 4 after any of trX calls:
>
> check(x < 4)
> {
> x, y = trA(x, z)
> y, z = trB(x, y) // no x on lhs, no check
> x, y = trC(y, z)
> break
> }
>
>
> // `check` helps the most where many repetitive checks
> // are to be performed in close proximity.
>
> check(err != nil)
> {
> ucred, err := getUserCredentials(user)
> remote, err := connectToApi(remoteUri)
> err, session, utok := remote.Auth(user, ucred)
> udata, err := session.getCalendar(utok)
>
> catch: // sad path, err != nil
> ucred.Clear() // cleanup passwords
> remote.Close() // do not leak sockets
> return nil, 0, // dress before leaving
> fmt.Errorf("Can not get user's Calendar because of: %v", err)
> }
> // happy path
>
>
> The proposal is at https://github.com/golang/go/issues/32968
>
> Please leave a comment for your possible thumb-down, as
> I would like to know about flaws I do not see as the author.
>
> Thank you,
>
> --
> Wojciech S. Czarnecki
> << ^oo^ >> OHIR-RIPE
>
> --
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