hopp@nbs-amrf.UUCP (Ted Hopp) (02/26/85)
Description:
This happened with version 2.9 of -me (version 2.1 of sh.me).
I defined the macro '$0', which is automatically called
from 'sh' when starting a new section, to log the section
name in a Table of Contents index. Occasionally '$0' would
get a null string as the section name. This occured when
'$p', which prints the section header for 'sh', triggered
a trap that causes an index entry to be generated. (I am
floating figures and entering the figure captions in a List
of Figures index when the figure is output.) Because of
the delayed processing of the index entry macros when they
are in a diversion such as a floating keep, they execute
during the trap processing.
The string '|x' is used by 'sh' to temporarily store the
section header, but it is also used by ')x' to store the
page number for the index entry. This destroys the value
of '|x' for 'sh', so '$0' gets a null string.
Repeat by:
Playing around with the location of a trap that causes
the index entry macros to be called just when a section
header is to be printed. Define '$0' to do something
with the section name; it will get a null string.
Fix:
I fixed 'sh' in \*(||/src/sh.me to redefine |x just before
calling '$0'. This seems kind of a kludge, but it works.
Old:
.if !"\\$2"_" \
\{\
. ds |x \&\\$2
. $p "\\*(|x" "\\*($n" \\n($0
. $0 "\\*(|x" "\\*($n" \\n($0
. rm |x
.\}
New:
.if !"\\$2"_" \
\{\
. ds |x \&\\$2
. $p "\\*(|x" "\\*($n" \\n($0
new --> . ds |x \&\\$2 \" in case |x got clobbered
. $0 "\\*(|x" "\\*($n" \\n($0
. rm |x
.\}
Is there a more elegant solution? I thought of calling
'$0' from '$p', but '$p' is called from 'sx' with no call
to '$0'. The real fix is to avoid conficting uses of '|x',
but I'm too lazy to figure out how to do that.
--
Ted Hopp {seismo,umcp-cs}!nbs-amrf!hopp