sage -rst2ipynb should provide a usefull message if rst2ipynb is not installed

[slabbe]

I get:

$ sage -rst2ipynb yo.rst yo.ipynb
/home/slabbe/GitBox/sage/src/bin/sage: ligne 775 : exec: rst2ipynb : non trouvé

???

[slabbe]

It seems to be the normal behavior when an optional package is not installed:

slabbe@miami bin $ sage -polymake
/home/slabbe/GitBox/sage/src/bin/sage: ligne 524 : exec: polymake : non trouvé
slabbe@miami bin $ sage -kash
/home/slabbe/GitBox/sage/src/bin/sage: ligne 559 : exec: kash : non trouvé

[slabbe]

When kash, polymake, etc. are not installed, the doc of sage -advanced says:

  -kash [...]         -- run Sage's Kash with given arguments
                         (not installed currently, run sage -i kash)
  -lisp [...]         -- run Lisp interpreter included with Sage
  -M2 [...]           -- run Sage's Macaulay2 with given arguments
                         (not installed currently, run sage -i macaulay2)
  -maxima [...]       -- run Sage's Maxima with given arguments
  -mwrank [...]       -- run Sage's mwrank with given arguments
  -polymake [...]     -- run Sage's Polymake with given arguments
                         (not installed currently, run sage -i polymake)

[slabbe]

I changed sage -advanced for rst2ipynb to do like the others kash and polymake, etc.

---

Last 10 new commits:

​2af3bfc	#23416 : let nbconvert write file and save images
​aa75e08	#23416 : postprocessing
​03e157c	Merge branch 'u/tmonteil/provide_a__sage__ipynb2rst__command' of trac.sagemath.org:sage into HEAD
​0785497	#23416 : command line doctest
​5ed5ab1	#23416 : remove depedency test to pandoc
​7897736	#23416 : typo
​30806a2	Merge branch 'u/tmonteil/provide_a__sage__ipynb2rst__command' of trac.sagemath.org:sage into HEAD
​f935b04	#23416 : has_pandoc doctest function
​6e37aa2	#23416 : update cmdline doctest
​459e5d3	25537: add doc to install rst2ipynb in sage -advanced

[tmonteil]

The code you provide does not fix the issue mentioned in the title and the description.

[slabbe]

Yes I know. Do you know how we could give better error messages to the user when not installed? You know bash more than me...

[tmonteil]

Here is some code that does the job, but i am not sure this makes consensus, regarding the other cases in the same script.

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New commits:

​8456392	Merge branch 'u/slabbe/25537' of trac.sagemath.org:sage into HEAD
​da7f22b	#25537 : trigger a message when rst2ipynb is not installed, comment 7.

[slabbe]

Do we lose something by removing the exec part ?

[slabbe]

ping:) please can you answer my small question before I can give positive review?

[slabbe]

ping

[tmonteil]

Replying to slabbe:

Do we lose something by removing the exec part ?

The way i wrote it, i would say no. The trick with exec is that the current process is replaced, hence after the command is finished, the further lines of the current script are not executed. This explains why, when removing the exec i had to catch the error (to send the appropriate message) and then be sure to exit.

The only drawback i see, is that the construction is different from the other cases in the script (that still use exec).

[slabbe]

Thanks for the clarifications.