[COFF] Shadowing variables in Go.
Ralph Corderoy
ralph at inputplus.co.uk
Tue Oct 1 23:20:59 AEST 2024
Taken to COFF...
Hi Arnold,
> In main(), I *think* I'm assigning to the global clientSet so that
> I can use it later. But because of the 'err' and the :=, I've
> actually created a local variable that shadows the global one, and in
> otherfunc(), the global clientSet is still nil. Kaboom!
>
> The correct way to write the code is:
>
> var err error
> clientSet, err = cluster.MakeClient() // or whatever
I think this is a common problem when learning Go, like assigning
getchar()'s value to a char in C. It was back in ’14 anyway, when I saw
https://www.qureet.com/blog/golang-beartrap/ which has an ‘err’ at an
outer scope be unwritten by the ‘:=’ with the new, assigned-to ‘err’
going un-checked.
The author mentions ‘go vet’ highlights these cases with -shadow, which
is off by default.
https://pkg.go.dev/github.com/golangci/govet#hdr-Shadowed_variables
suggests that's still the case.
--
Cheers, Ralph.
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