Re: wrapper functions in modules

["Bart Schaefer" <schaefer@brasslantern.com>]

On Dec 11,  3:16pm, Sven Wischnowsky wrote:
} Subject: Re: wrapper functions in modules
}
} [...] my first idea was to let modules register only one function
} which would have to call back the execution code [...]
} This would solve the call stack problems you mentioned. Also, writing
} wrappers would be easier in modules since you can use local variables, 
} static local variables for number-of-calls and so on...

This would indeed be an improvement.  An interesting side-effect is that
it would permit a module to decide not to run the shell function at all;
it could instead branch off into any code it liked.

That in turn probably makes modules even more dangerous than before, from
a run-time perspective.  An innoccuous module placed in root's module path
could suddenly have someone else driving the shell.  It might even be a
good idea to have zsh refuse to dynamically load modules when EUID==0, or
at least refuse to auto-load them.

} About the problems with unloading: I would vote for completely
} disallowing to unload a module if a wrapper is active for it.
} This is relatively easy to keep track of and seems to be the savest

(Safest.)  This still isn't quite good enough -- you can't unload
modules upon which other modules depend, so if X has a wrapper and
depends on Y, you can't unload Y even though Y has no wrapper.

This probably means you end up refusing to unload any modules at all
whenever there are any wrappers at all, which may be problematic.

} the question is: how often does one want to unload modules in shell
} functions?

I could envision someone wanting to write a pair of functions, one that
installs several related modules and another that uninstalls them again.

} Finally about the order in which installed wrappers are to be called:
} looking at load_module() it should be enough to build the wrappers
} list by appending new definitions to the end.

Yes, as I said, if the only constraint is module dependencies this will
work fine.

Side note to Phil Pennock:  If we get this worked out, then an emulator
module for ksh would be the perfect way to fudge WORDCHARS and various
keybindings for later restoration ...

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com