Hi Eric, see comments inline.


On Thu, Mar 27, 2014 at 6:43 PM, Eric Schulte <schulte.eric@gmail.com>wrote:

> Hi Pascal,
>
> This looks like a good patch.  If I could make three changes/requests.
>
>
Thanks, I am happy to see it makes sense.


> 1. This patch should also work for "begin_src bash" code blocks.  After
>    a very quick glance it doesn't appear to.
>
> I have actually tried this with the latest org-mode release (8.2.5h) and
it did plainly not accept 'begin_src bash'. Maybe that's new with the
ob-shell.el (I noticed it has been renamed :-)


> 2. Could you include one or two tests ensuring that this patch does what
>    it intends with bash code blocks, and does not affect code blocks
>    executed with bin/sh?
>

Will do, seeing it has some traction.


>
> 3. Large contributions like this require some FSF paperwork.  Please see
>    the following page for information on requirements to contribute.
>
>
I checked internally, and apparently, Google has already such a signed
document. It would run on the same document, as I am a google employee.


>    http://orgmode.org/worg/org-contribute.html
>
> Thanks, and I look forward to seeing this merged into Org-mode!
> Eric
>
> Pascal Fleury <fleury@google.com> writes:
>
> > Hello,
> >
> > I'dl like to propose a patch for inclusion into org-mode (ob-shell.el in
> > particular).
> >
> > *TL;DR:* use arrays and associative arrays when exporting variables to
> bash
> > in 'sh' code blocks.
> >
> > *Details:*
> > When variables are defined in a 'sh' code block, they are exported as
> > strings. when the variable itself is an array or a table, then we simply
> > get a shell variable that contains the list of all values in a
> > non-structured form. E.g.
> >
> > #+NAME: my_list
> > | one   |
> > | two   |
> > | three |
> >
> > #+NAME: experiment
> > | name | first_attempt    |
> > | date | [2014-03-27 Thu] |
> > | user | fleury           |
> >
> > #+BEGIN_SRC sh :var scalar="some value" :var array=my_list :var
> table=config
> > echo ${scalar}  # -> prints 'some value'
> > echo ${array}   # -> prints 'one two three'
> > echo ${table}   # -> prints 'first attempt [2014-03-27 Thu] fleury'
> > #+END_SRC
> >
> > This will print simple strings. Also, there is no easy way to access the
> > date of the experiment, for example. Now bash has things like arrays and
> > associative arrays, but the current ob-shell.el does not use these.
> > Probably because their syntax is bash-specific, and ob-shell.el is
> > shell-agnostic.
> >
> > My patch (attached) changes this in the case you have
> > (setq org-babel-sh-command "bash")
> > in your emacs config somewhere. If any other value is used, it continues
> to
> > export them as we do today (I don't know enough about other shells).
> >
> > In that case, it will export the list as an array, the table as an
> > associative array, and the scalar as it does already. So the 'sh' code
> > block could then use
> >
> > #+BEGIN_SRC sh :var scalar="some value" :var array=my_list :var
> table=config
> > echo ${scalar}
> > echo ${array[1]} # -> prints "two"
> > echo ${table[user]} # -> prints "fleury"
> > #+END_SRC
> >
> > In the case we have a bigger table, then the first row is used as key,
> the
> > others are represented as a string with all the values (as it is for
> array
> > currently). bash does not have multi-dimensional arrays, so it needs to
> be
> > a string.
> >
> > This makes writing shell snippets much easier in my experience, and there
> > I'd like to propose this fix for the org-mode community at large.
> >
> > --paf
> >
> > diff --git a/lisp/ob-shell.el b/lisp/ob-shell.el
> > index 3ede701..0a691e2 100644
> > --- a/lisp/ob-shell.el
> > +++ b/lisp/ob-shell.el
> > @@ -106,6 +106,30 @@ This function is called by
> `org-babel-execute-src-block'."
> >
> >  ;; helper functions
> >
> > +(defun org-babel-variable-assignments:bash_array (varname values
> &optional sep hline)
> > +  "Returns a list of statements declaring the values as a bash array."
> > +  (format "declare -a %s=( \"%s\" )"
> > +     varname
> > +     (mapconcat 'identity
> > +       (mapcar
> > +         (lambda (value) (org-babel-sh-var-to-sh value sep hline))
> > +         values)
> > +       "\" \"")))
> > +
> > +(defun org-babel-variable-assignments:bash_associative (varname values
> &optional sep hline)
> > +  "Returns a list of statements declaring the values as bash
> associative array."
> > +  (format "declare -A %s\n%s"
> > +    varname
> > +    (mapconcat 'identity
> > +      (mapcar
> > +        (lambda (items)
> > +          (format "%s[\"%s\"]=%s"
> > +            varname
> > +            (org-babel-sh-var-to-sh (car items) sep hline)
> > +            (org-babel-sh-var-to-sh (cdr items) sep hline)))
> > +        values)
> > +      "\n")))
> > +
> >  (defun org-babel-variable-assignments:sh (params)
> >    "Return list of shell statements assigning the block's variables."
> >    (let ((sep (cdr (assoc :separator params)))
> > @@ -114,9 +138,17 @@ This function is called by
> `org-babel-execute-src-block'."
> >                    "hline"))))
> >      (mapcar
> >       (lambda (pair)
> > -       (format "%s=%s"
> > -            (car pair)
> > -            (org-babel-sh-var-to-sh (cdr pair) sep hline)))
> > +       (if (and (string= org-babel-sh-command "bash") (listp (cdr
> pair)))
> > +         (if (listp (car (cdr pair)))
> > +           (org-babel-variable-assignments:bash_associative
> > +           (car pair) (cdr pair) sep hline)
> > +           (org-babel-variable-assignments:bash_array
> > +           (car pair) (cdr pair) sep) hline)
> > +         (format "%s=%s"
> > +         (car pair)
> > +         (org-babel-sh-var-to-sh (cdr pair) sep hline))
> > +       )
> > +     )
> >       (mapcar #'cdr (org-babel-get-header params :var)))))
> >
> >  (defun org-babel-sh-var-to-sh (var &optional sep hline)
>
> --
> Eric Schulte
> https://cs.unm.edu/~eschulte
> PGP: 0x614CA05D
>



-- 
--paf