Re: Load autoloadable function, but only in enclosing function scope

[Peter Stephenson <p.w.stephenson@ntlworld.com>]

On Thu, 2022-03-24 at 10:51 -0700, Bart Schaefer wrote:
> On Thu, Mar 24, 2022 at 10:06 AM Peter Stephenson
> <p.w.stephenson@ntlworld.com> wrote:
> > 
> > With that key limitation --- if you've already got functions with the
> > names of the ones you're creating, you're stuffed --- you can automate
> > it like this.
> > 
> > fn() {
> >   local -a oldfuncs=(${(k)functions})
> 
> It actually can be even shorter than that, depending on how carefully
> the context needs to be preserved.  Peter's example keeps the
> definitions of any functions that were previously defined, even if
> those definitions were replaced (by autoload execution or explicit
> redefinition).  The example below restores all the function
> definitions to their previous state, even when replaced.  (Native zsh
> mode semantics assumed below.)
> 
> foo() { print original foo }
> bar() {
>   local funcs=(${(kv)functions}
>   {
>     foo() { print the bar foo }
>     foo
>   } always {
>     functions=($funcs)
>   }
> }
> 
> This does have side-effects for autoloaded functions; they become
> defined with "builtin autoload -X" as the body, which doesn't always
> work the same way as a true autoload.

It's got side effects for other fucntions, which is that that the line
numbers recorded no longer match those in the file the function is
autoloaded from (you don't see those unless you're using a debug
prompt or equivalent).

You're also at the mercy of zsh's ability to convert internal structures
into text and back, which is supposed to work, though not particularly
efficiently.

pws