Re: [Help-bash] make function local

[Greg Wooledge]

On Fri, Apr 10, 2015 at 09:13:17AM -0500, Eduardo A. Bustamante López wrote:
> Now, for the features in bash that'd be actually useful:
> 
> - discipline functions and compound datatypes (like in ksh)
> - a way to do wrap arbitrary OS system calls with a builtin, so that instead 
> of
> having thousands of builtins each interacting with the system, we could just
> do: `syscall lstat foo' and get something useful.

(Even adding *just* examples/loadables/finfo as a standard builtin would
be so helpful!  But we also get a huge number of requests for readlink.)

> - a faster implementation of the variable lookup code
> - a shopt to disable evaluation of shell code in places like arithmetic
> expansion
> - a better way to deal with binary input (specially NUL bytes)
> - and many more, these are the ones I can think of right now

Yeah, same here.  I didn't know I was going to be quizzed on this, or
I would have studied.

- Fix the $"..." security hole (I tried and failed).
  http://www.gnu.org/software/gettext/manual/html_node/bash.html

- Pass caller-scope scalar and array variable names to a function, and
  use them in the called function safely (like declare -n except safe
  to use) (like ksh's nameref).

- User-specified delimiter character on readarray/mapfile (I hear this is
  already done).

- Sorting arrays without having to call nonstandard GNU sort -z.

- printf '%(%s)T' or equivalent support on systems that don't have %s
  in strftime() (because those systems also don't have date +%s).

- Multi-character join, like "${array[*]}" but using more than just the
  first character of IFS.  (Like [join $list ", "] in Tcl.)
  (Currently, can be hacked by doing
    printf -v tmp "%s, " "${array[@]}"
    tmp=${tmp%, }
  so not a high priority.)

As someone who has never used languages with "local functions", I don't
really see what good they are.  I certainly wouldn't put them at the
top of any "new feature" list.