Re: Local history

[Peter Stephenson <pws@csr.com>]

Bart Schaefer wrote:
> As Sven mentioned, I've done this before.  The basic trick is that HISTSIZE
> truncates the history as soon as you assign to it, so the technique goes
> like this:
> 
> 	local temphist=${TMPPREFIX}hist SAVEHIST=$HISTSIZE
> 	HISTFILE=$temphist
> 	fc -W				# Save internal history
> 	local HISTSIZE=0		# Truncate internal history
> 	HISTSIZE=$SAVEHIST
> 	HISTFILE=~/.zcalc-history
> 	fc -R				# Read previous zcalc history
> 	# do zcalc stuff ...
> 	fc -W				# Save zcalc history
> 	HISTFILE=$temphist
> 	fc -R				# Reload old history

That should obviously restore the original HISTFILE at the second last
line.

I adapted this into the following, and it's mostly working fine.  However,
every time it saves back to ~/.zcalc_history, it adds two lines from the
old history at the start which I can't seem to get rid of.  Possibly
trimming SAVEHIST to the actual number of lines to save might work.

Index: Functions/Misc/zcalc
===================================================================
RCS file: /cvsroot/zsh/zsh/Functions/Misc/zcalc,v
retrieving revision 1.5
diff -u -r1.5 zcalc
--- Functions/Misc/zcalc	2001/11/15 18:42:33	1.5
+++ Functions/Misc/zcalc	2001/11/19 17:27:44
@@ -88,6 +88,25 @@
 emulate -L zsh
 setopt extendedglob
 
+# can't be local since required in EXIT trap
+zcalc_orighist=$HISTFILE 
+local temphist=${TMPPREFIX}hist SAVEHIST=$HISTSIZE
+HISTFILE=$temphist
+fc -W
+
+local HISTSIZE=0
+HISTSIZE=$SAVEHIST
+HISTFILE=~/.zcalc_history
+[[ -f $HISTFILE ]] && fc -R
+
+zcalc_restore() {
+    unfunction zcalc_restore
+    fc -W
+    HISTFILE=$zcalc_orighist
+    fc -R
+}
+trap zcalc_restore HUP INT QUIT EXIT
+
 local line latest base defbase match mbegin mend psvar optlist opt arg
 integer num
 
-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 392070


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