Shadowing variables in Go. - COFF

1 Oct 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.