On Friday, January 11, 2013 09:48:32 PM John Kearney wrote:
> Am 11.01.2013 19:27, schrieb Dan Douglas:
> > Bash treats the variable as essentially undefined until given at least an
> > empty value.
> >
> > $ bash -c 'typeset -i x; [[ -v x ]]; echo "$?, ${x+foo}"; typeset -p x'
> > 1,
> > bash: line 0: typeset: x: not found
> > $ ksh -c 'typeset -i x; [[ -v x ]]; echo "$?, ${x+foo}"; typeset -p x'
> > 0,
> > typeset -i x
> >
> > Zsh implicitly gives integers a zero value if none are specified and the
> > variable was previously undefined. Either the ksh or zsh ways are fine IMO.
> >
> > Also I'll throw this in:
> >
> > $ arr[1]=test; [[ -v arr[1] ]]; echo $?
> > 1
> >
> > This now works in ksh to test if an individual element is set, though it
> > hasn't always. Maybe Bash should do the same? -v is tricky because it adds
> > some extra nuances to what it means for something to be defined...
> >
>
> Personally I like the current behavior, disclaimer I use nounset.
> I see no problem with getting people to initialize variables.
How is this relevant? It's an inconsistency in the way set/unset variables
are normally handled. You don't use variadic functions? Unset variables /
parameters are a normal part of most scripts.
> it is a more robust programming approach.
I strongly disagree. (Same goes for errexit.)
--
Dan Douglas
