choice of implementation language

[Bruno Haible]

If gnulib-tool was to be rewritten in another programming language than
shell + sed, what would be the good choices?

The foremost criteria IMO should be the maintainability, i.e. the ability for
us and for new contributors to gnulib to master this programming language.
To get an estimate of this, there are various sources of information.

1) We can look at the number of developers who master one language or the
   other. This matters because we cannot force or expect gnulib contributors
   to learn a new programming language, just for gnulib-tool.

   I compared C, C++, Java, shell-script, Python, Perl in ohloh:
   
<http://www.ohloh.net/languages/compare?commit=Update&l0=c&l1=java&l2=perl&l3=python&l4=shell&l5=cpp&l6=-1&measure=contributors&percent=>
   The result is the following ordered list:
     1. C
     2. Java
     3. C++
     4. Python
     5. perl
   The comparison by number of projects rather than by number of developers
   
<http://www.ohloh.net/languages/compare?commit=Update&l0=c&l1=java&l2=perl&l3=python&l4=shell&l5=cpp&l6=-1&measure=projects&percent=>
   yields the same result.

2) We can also look at the level of familiarity of the current gnulib-tool
   maintainers with these languages. Among us recent contributors to gnulib-tool
   (Eric, Jim, Ralf, Simon, and me) two of us have made public their skills:
   <http://savannah.gnu.org/people/resume.php?user_id=1389>
   <http://savannah.gnu.org/people/resume.php?user_id=1871>
   making up for:
     C      - 2 x master/expert
     Java   - 2 x master/expert
     C++    - 1 x master/expert, 1 x good knowledge
     Python - 1 x base knowledge
     perl   - 1 x base knowledge

   Also, I know that a few years ago Paul did not know C++ and was not inclined
   to learn it.

   So according this criteria, only C and Java remain possibilities. Python and
   perl have to be excluded because too few of us are skilled in these 
languages.

3) Long-term maintainability requires some degree of standardization, so
   that the amount of expected future changes in the language and its runtime
   library is small. This speaks in favour of C, Java, C++, and against
   Python and perl.

4) For comparing simply the syntactic complexity of the languages (yes this
   is only a small facet of maintainability, but nevertheless), one can take
   the amount of code needed for writing a superficial parser. Such parsers
   are implemented in gettext/gettext-tools/src/x-*.c, and x-perl.c is more
   than twice as large as the other parsers. This indicates that also for a
   human developer, perl syntax is harder to grok than the syntax of other
   programming and scripting languages.

In summary, C and Java come out as best candidates, whereas a choice of python
or perl would be very unwise.

Bruno