Re: [PATCH] Yet another shell function prerequisite!

[Paolo Bonzini]

Ralf Wildenhues wrote:
> * Paolo Bonzini wrote on Mon, Oct 13, 2008 at 07:24:10PM CEST:
>> I'd okay with -, but what if unset does not work?  I planned to do
>> something like
>>
>>   as_lineno=; AS_UNSET([as_lineno])
>>
>> but that could expand to
>>
>>   as_lineno=; false as_lineno
>>
>> Do we still care about "old BSD shells, including the Ultrix sh"?  How
>> old are these?
> 
> Let's go with unset.  IIRC unset is more portable than ${var:-default}
> (and IIRC, where the latter doesn't work, it causes the shell to abort
> the script).  Having line number information fail if both are borked is
> tough luck.

In the meanwhile I thought about

  as_lineno=${as_lineno-$LINENO} func

which is a slick trick, as it supports nesting and does not require
unset.  :-)

I'll commit the attached testcase together with the patch at the top of
the thread:

2008-10-14  Paolo Bonzini  <address@hidden>

        * tests/m4sh.at (Function pseudo-local variables): New test.

diff --git a/tests/m4sh.at b/tests/m4sh.at
index e7ea7aa..3183932 100644
--- a/tests/m4sh.at
+++ b/tests/m4sh.at
@@ -475,6 +475,34 @@ AT_CHECK([./script])
 AT_CLEANUP


+## ------------------------ ##
+## Pseudo-local variables.  ##
+## ------------------------ ##
+
+AT_SETUP([Function pseudo-local variables])
+AT_KEYWORDS([m4sh])
+
+AT_DATA_M4SH([script.as],
+[[AS_INIT
+AS_REQUIRE_SHELL_FN([func_var], [var=$var${a-B}])
+
+func_var
+a=b func_var
+func_var
+b=c
+a=${a-$b} func_var
+func_var
+if test $var != BbBcB; then
+  AS_ERROR([func_var test failed])
+fi
+]])
+
+AT_CHECK_M4SH
+AT_CHECK([./script])
+
+AT_CLEANUP
+
+
 ## ------------------------------------ ##
 ## AS_REQUIRE_SHELL_FN and m4_require.  ##
 ## ------------------------------------ ##