Python embedded in COBOL

[btiffin]

Well met,

Old guys like COBOL, you should too. Really. It might score you a bank, or government gig someday.

code:

OCOBOL >>SOURCE FORMAT IS FIXED       *> ***************************************************************       *> Author:    Brian Tiffin       *> Date:      20130126       *> Purpose:   Embed Python       *> Tectonics: cobc -x cobkat.cob -lpython2.6       *>     NOTES:    leaks, no Py_DECREF macros called.       *> ***************************************************************        identification division.        program-id. cobkat.        data division.        working-storage section.        77 python-name          usage pointer.        77 python-module        usage pointer.        77 python-dict          usage pointer.        77 python-func          usage pointer.        77 python-stringer      usage pointer.        77 python-args          usage pointer.        77 python-value         usage pointer.            01 cobol-buffer-pointer usage pointer.           01 cobol-buffer         pic x(80)                       based.        01 cobol-string         pic x(80).        01 cobol-integer        usage binary-long.        01 command-line-args    pic x(80).       *> ***************************************************************        procedure division.       *> let python scan current work dir for scripts        set environment "PYTHONPATH" to "."       *> init the engine, hint if link lib problem        call "Py_Initialize"            on exception                display "link cobpy with -lpython" end-display        end-call               *> Python likes module names in Unicode        call "PyUnicodeUCS4_FromString" using            by reference "pythonfile" & x"00"            returning python-name            on exception                display "unicode problem" end-display        end-call       *> import the module, using PYTHONPATH        call "PyImport_Import" using            by value python-name            returning python-module            on exception                display "this would be borked" end-display        end-call        if python-module equal null            display "no pythonfile.py in PYTHONPATH" end-display        end-if       *> within the module object, an attribute is "pthonfunction"        call "PyObject_GetAttrString" using            by value python-module            by reference "pythonfunction" & x"00"            returning python-func            on exception continue        end-call       *>       *> error handling now skimped out on       *>       *> pythonfunction takes a single argument        call "PyTuple_New" using            by value 1            returning python-args        end-call         *> of type long, hard coded to the ultimate answer        call "PyLong_FromLong" using            by value 42            returning python-value        end-call       *> set first (only) element of the argument tuple        call "PyTuple_SetItem" using            by value python-args            by value 0            by value python-value        end-call       *> call the function, arguments marshalled for Python        call "PyObject_CallObject" using            by value python-func            by value python-args            returning python-value        end-call       *> we know we get a long back, hopefully 1764        call "PyLong_AsLong" using            by value python-value            returning cobol-integer        end-call        display "Python returned: " cobol-integer end-display       *> ************************************************************ *<       *> Interface to a function taking string and returning string        call "PyObject_GetAttrString" using            by value python-module            by reference "pythonstringer" & x"00"            returning python-stringer        end-call        call "PyTuple_New" using            by value 1            returning python-args        end-call         *> Use the OpenCOBOL command argument        accept command-line-args from command-line end-accept        call "PyString_FromString" using            by reference                function concatenate(                    function trim(command-line-args)                    x"00")            returning python-value        end-call       *> Set the function argument tuple to point to the cli args        call "PyTuple_SetItem" using            by value python-args            by value 0            by value python-value        end-call         *> call the "pythonstringer" function        call "PyObject_CallObject" using            by value python-stringer            by value python-args            returning python-value        end-call       *> return as String (with pythonstringer MD5 hex digest tacked on)        call "PyString_AsString" using            by value python-value            returning cobol-buffer-pointer        end-call       *> one way of removing null bytes and pulling data out of C        set address of cobol-buffer to cobol-buffer-pointer        string            cobol-buffer delimited by x"00"            into cobol-string        end-string        display "Python returned: " cobol-string end-display       *> and clear out <*        call "Py_Finalize" end-call        goback.        end program cobkat.

and this short test python script

code:

# # Simple Python sample for OpenCOBOL embedding demonstration # def pythonfunction(i):     return i * i import hashlib def pythonstringer(s):     sum = hashlib.md5()     sum.update(s)     return s + ": " + sum.hexdigest()

with OpenCOBOL 1.1 installed, and Python 2.6 (in this case) compiles and runs as:

code:

$ cobc -x -lpython2.6 cobkat.cob $ ./cobkat Some command line arguments that get MD5 Python returned: +0000001764 Python returned: Some command line arguments that get MD5: 7015e114db6f4d41d7458cef9e6b5e49

Cheers