On 06/29/2010 12:35 PM, Ralf Wildenhues wrote:
> * Gary V. Vaughan wrote on Tue, Jun 29, 2010 at 08:30:43PM CEST:
>> On 30 Jun 2010, at 01:22, Ralf Wildenhues wrote:
>>> I think m4sh can simply use code like
>>>
>>> if ( eval '$smart_works' ) >/dev/null 2>&1; then
>>> func_foo () { smart code; }
>>> else
>>> func_foo () { safe code; }
>>> fi
>>>
>>> for code run a handful of times, without need for extra m4 magic, it's
>>> just that libtool is easily run hundreds of times in a typical large
>>> software build so it warrants optimization.
>>
>> In that case might the retarded shell choke and die as it parses 'smart
>> code;'?
>
> Good point. IIRC gnulib-tool uses e.g.,
> eval 'func_foo () { smart code; }'
That's how m4sh already does it for AS_VAR_APPEND (take a look at
practically any configure script built with recent autoconf):
if (eval "as_var=1; as_var+=2; test x\$as_var = x12") 2>/dev/null; then :
eval 'as_fn_append ()
{
eval $1+=\$2
}'
else
as_fn_append ()
{
eval $1=\$$1\$2
}
fi # as_fn_append
which works just fine with retarded Solaris /bin/sh.
--
Eric Blake ebl...@redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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