New CWM extension

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New CWM extension

Atila
Hi, I have built a little cwm extension that creates built-ins on the fly.

When a URI like <python://mymodule#myfunction> is found in a rule,
it imports the module and uses the function as a built-in.

Example:
teste.n3:

     :c :input ("All these worlds are yours except europa") .

     {?x :input (?y).
         ?z1b <python://#unicode.upper> (?y) .
         ?z2 <python://#unicode.rsplit> ( ?z1b " " 2 ) .
     }=>{
         ?x :output ?z2.
     }.

cwm_py.py --think --data teste.n3

      @prefix : <#> .

     :c     :input  (
         "All these worlds are yours except europa" );
          :output  (
         "ALL THESE WORLDS ARE YOURS"
         "EXCEPT"
         "EUROPA" ) .

The equivalent python code would be y.upper.rsplit(" ", 2)

Another example, a little more useful, would be to put a custom function
in a file, like teste.py
and use that function as a built-in:

teste.py:

     import subprocess
     def callExt(arglist):
         return
subprocess.Popen(arglist,stdout=subprocess.PIPE).communicate()[0]

teste.n3:

     @prefix teste: <python://teste#>.
     :d :input ().
     {?x :input ().
         ?z1 teste:callExt (("ls" "-l" "../")) .
     }=>{
         ?x :output ?z1.
     }.

cwm_py.py --think --data teste.n3

      @prefix : <#> .

     :d     :input ();
          :output """total 16
drwxrwxr-x  2 atila.alr atila.alr  4096 Mai  9 08:52 CVS
drwxrwxr-x 26 atila.alr atila.alr 12288 Mai 17 17:54 swap
""" .

To "install" the extension, it should suffice to put cwm_py.py in the
cwm.py folder.
Then, to use it, call cwm_py.py like you would call cwm.
Internally, all the extension does is to monkeypatch an internal
function (so it understand "python://" URI)
and then pass the ball to cwm.

Sure, the idea of call any function is not very
production-security-friendly, but it may come handy in a controlled
environment.

The code is at https://github.com/atilaromero/cwm_py/blob/master/cwm_py.py

If anyone like it, let me know.