Hey gophers,
there recently was a thread on /r/golang, about whether or not to
explicitly return useless values when an error occurred, or to just not
care, as the caller isn't supposed to use a return value on a non-nil value
anyway. So, say, I have a type that wraps an *os.File (or a database
handle, or such). And has some method that initializes state. Which is
better:
func OpenFoo(fname string) (*Foo, error) {
f := &Foo{}
if err := f.initializeState(f, fname); err != nil {
return nil, err
}
return f, nil
}
or
func OpenFoo(fname string) (*Foo, error) {
f := &Foo{}
return f, f.initializeState(f, fname)
}
(leaving aside both whether it's a good pattern to have such a separate
initialization method or not and whether to first assign its result to a
variable and then return that).
I usually prefer the former; while it's true that the return value
shouldn't matter in the error-case as there is no guarantee about it, I
don't think it costs anything to explicitly return nil in that case and
thus make sure, that if a caller does forget that rule, they will simply
crash, instead of continuing with a value in an invalid state.
Other people seem to feel very differently, very strongly. Their argument
seems to be a) that the zero value should be useful anyway and b) "I am
complicating things and should just check the error". I want to emphasize
that I agree with both of these rules, just that *if* I can't make the zero
value useful (and if it is, why would I need a constructor at all?), there
isn't a cost to also explicitly return something that will blow up quickly
in the error case, so that *if* the user of my package (or I) accidentally
not do the error-check correctly, it will make it a tiny bit easier to
debug.
As this seems to be a not un-contentious issue and is also something I
regularly suggest in code-reviews for colleagues to do, I would like to
solicit further opinions on this; am I being unreasonable? Am I
recommending practices that makes worse go devs?
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