Re: [9fans] Local variables and rc functions

["roger peppe" <rogpeppe@gmail.com>]

On Thu, Aug 14, 2008 at 12:20 PM, kazumi iwane <kiwane@gmail.com> wrote:
> if you want to delay the expansion of an env var until fn invocation,,use eval.
>
> % fn foo {eval echo $$bar}

sorry, but that's so, so wrong.

1)  $$bar gives the value of the variable
named by the contents of the variable bar,
so that the above, given that $bar contains 'baz'
will echo $baz.

2) $$bar above is evaluated _before_ eval is invoked,
so the line is not very different from {echo $$bar}, except that
if $$bar holds any syntax characters they'll get interpreted by the shell.
it's almost never necessary to use eval with rc.

3) expansion of env. vars *is* delayed until fn invocation.
e.g.
% fn foo {echo $bar}
% bar = baz
% foo
baz
%

it just seems as if the local variable assignment isn't propagated
into the fn context. i don't have time to look into it now (i really
shouldn't be spending time writing this email, but i couldn't resist the bait).

  rog.