On Wed, May 19, 2004 at 10:37:50PM +0100, Peter Stephenson wrote:
> Probably allowing it with both would be better, since `history' is a more
> natural command.

I agree that the command name reads better, but since it has always
implied listing of history entries, it seems a little weird to change
that.  I went ahead and added the -p & -P options to the history
builtin, but I didn't document it yet.

> Looks essentially OK to me as it is, it can be enhanced later if we
> feel like it.

OK, I checked it in.  I also started to work on an auto-pop feature
from a function.  Attached is a patch that almost works right, but has a
couple areas that need to be improved.  Perhaps someone can chime in
here with some advice on how to either do this the right way or fix the
problems.

I chose to add my pop-checking hook into level() -- the routine that
decrements locallevel.  One problem I encountered is that this routine
is called on function exit _before_ the traps are run.  This means that
if someone puts a manual "fc -P" call into a trap, it will try to do
an extra pop after the auto-pop for leaving the function.  I suppose we
can just tell people not to do that...

The other problem I noticed is how the saving of the parameters
interacts with local variables.  Take these two functions for instance:

function foo {
    local HISTSIZE=2221
    fc -p ~/.newhist 2222 2222
    echo $HISTFILE $HISTSIZE
}

function bar {
    fc -p
    local HISTFILE=~/.newhist HISTSIZE=2223
    echo $HISTFILE $HISTSIZE
}

In function foo the history-list push saves off the 2221 from the local
variable, so we have to be sure to call the history-list pop function
before removing the local variables (which is what I currently do).

However, in function bar the history-list push saves off the global
value of the HISTFILE and HISTSIZE variables, which are then made local.
When the function exits, the history-list pop first restores the global
values of the variables to the environment, and then the local-variable
restoration unsets HISTFILE and makes HISTSIZE=30 (the default value).

Is this something we can easily fix?  Perhaps with a different way of
saving the environment values?  Or is this something where we tell users
that they can't both use "fc -p" and make the variables local?

..wayne..