(split-string-and-unquote (combine-and-quote-strings STRINGS)) fails on trivial case

(split-string-and-unquote (combine-and-quote-strings STRINGS)) fails on trivial case

[Joe Wells]

The documentation strings for both split-string-and-unquote and
combine-and-quote-strings state that they attempt to achieve this
property:

  (split-string-and-unquote (combine-and-quote-strings strs)) == strs

Here is a trivial case that they fail on; the following sexp wrongly
evaluates to nil:

  (let ((l '("a b" "c")))
    (equal l
           (split-string-and-unquote (combine-and-quote-strings l))))

I hope this problem report is helpful.

Joe

======================================================================
In GNU Emacs 22.2.1 (i686-pc-linux-gnu, GTK+ Version 2.8.20)
 of 2008-04-01 on artemis
Windowing system distributor `The X.Org Foundation', version 11.0.70000000
configured using `configure  '--prefix=/home/jbw/local4' '--enable-debug' '--disable-nls' '--with-x-toolkit=gtk' 'CFLAGS=-O0 -g3 -ggdb -fno-crossjumping -DGLYPH_DEBUG=1''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: en_US.UTF-8
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: jbw
  value of $LANG: nil
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t


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Re: (split-string-and-unquote (combine-and-quote-strings STRINGS)) fails on trivial case

[Chong Yidong]

> The documentation strings for both split-string-and-unquote and
> combine-and-quote-strings state that they attempt to achieve this
> property:
>
>   (split-string-and-unquote (combine-and-quote-strings strs)) == strs
>
> Here is a trivial case that they fail on; the following sexp wrongly
> evaluates to nil:
>
>   (let ((l '("a b" "c")))
>     (equal l
>            (split-string-and-unquote (combine-and-quote-strings l))))

I think this is a docstring mistake.  IIUC, the equation

 (split-string-and-unquote (combine-and-quote-strings strs)) == strs

only holds if STRS is a list containing a single string.  The point the
docstrings are trying to make is that combine-and-quote-strings performs
string quoting, while split-string-and-unquote performs unquoting.

If there are no objections to this interpretation, I'll check in a doc
fix shortly.