Python provides access to dictionaries holding the local variables of
a function using locals() as well as the global variables stored
as attributes to the module to which the function belongs as
globals(). The Python C API provides
PyEval_GetLocals() and PyEval_GetGlobals(), but these
return the scope of the Janus API function rather than user code, i.e.,
the global variables of the janus module and the local
variables of the running Janus interface function.
Python code that wishes Prolog to access its scope must pass the
necessary scope elements (local and global variables) explicitly to the
Prolog code. It is possible to pass the entire local and or global scope
by the output of locals() and/or
globals(). Note however that a dict passed to Prolog is
translated to its Prolog representation. This representation may be
prohibitively large and does not allow Prolog to modify variables in the
scope. Note that Prolog can access the global scope of a module as
attributes of this module, e.g.
increment :-
py_call(demo:counter, V0),
V is V0+1,
py_setattr(demo, counter, V).
