Re: [gentoo-dev] Re: evar_push/pop helpers

[Mike Frysinger <vapier@gentoo.org>]

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On Monday 17 June 2013 01:42:15 Mike Frysinger wrote:
> On Sunday 02 June 2013 13:38:04 Steven J. Long wrote:
> > On Sat, Jun 01, 2013 at 11:03:20PM -0400, Mike Frysinger wrote:
> > > +# is not specified, the var will be unset.
> > > +evar_push_set() {
> > > +	local var=$1
> > > +	evar_push ${var}
> > > +	case $# in
> > > +	1) unset ${var} ;;
> > > +	2) eval ${var}=\$2 ;;
> > 
> > I wish you wouldn't use eval for this. I know it's technically okay here,
> > or would be if you verified the parameter, but bash has printf -v for
> > this purpose:
> 
> interesting, i hadn't seen that before ... looks new to bash-3.1.  /me
> tucks that into his tool belt.
> 
> although it doesn't quite work in the edge case where the value is an empty
> string.  consider:
> 	unset x
> 	printf -v x ''
> 	echo ${x+set}
> 
> that should show "set", but it does not.  i'll have to keep `eval ${var}=`
> when the value we're setting is empty.  or just keep the eval code since i
> have to do eval anyways at that point.
> 
> i'll report it upstream to the bash guys.

looks like it can be worked around by doing:
	printf -v x '%s' ''
which is arguably what we want anyways
-mike

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