[Python-Dev] Changing the Division Operator -- PEP 238, rev 1.12

[Michael Hudson]

Samuele Pedroni <pedroni@inf.ethz.ch> writes:

> [GvR]
> > 
> > > [Michael Hudson]
> > > >     One - probably called Compile - will sport a __call__ method which
> > > >     will act much like the builtin "compile" of 2.1 with the
> > > >     difference that after it has compiled a __future__ statement, it
> > > >     "remembers" it and compiles all subsequent code with the
> > > >     __future__ options in effect.
> > > > 
> > > >     It will do this by examining the co_flags field of any code object
> > > >     it returns, which in turn means writing and maintaining a Python
> > > >     version of the function PyEval_MergeCompilerFlags found in
> > > >     Python/ceval.c.
> > 
> > > FYI, in Jython (internally) we have a series of compile_flags functions
> > > that take a "opaque" object CompilerFlags that is passed to the function
> > > and compilation actually change the object in order to reflect future
> > > statements encoutered during compilation...
> > > Not elegant but avoids code duplication.
> > > 
> > > Of course we can change that.
> > 
> > Does codeop currently work in Jython?  The solution should continue to
> > work in Jython then. 
> We have our interface compatible version of codeop that works.

Would implementing the new interfaces I sketched out for codeop.py be
possible in Jython?  That's the bit I care about, not so much the
interface to __builtin__.compile.

> > Does Jython support the same flag bit values as
> > CPython?  If not, Paul Prescod's suggestion to use keyword arguments
> > becomes very relevant.
> we support a subset of the co_flags, CO_NESTED e.g. is there with the same
> value.
> 
> But the embedding API is very different, my implementation of nested
> scopes does not define any Py_CF... flags, we have an internal CompilerFlags
> object but is more similar to PyFutureFeatures ...

Is this object exposed to Python code at all?  One approach would be
PyObject-izing PyFutureFlags and making *that* the fourth argument to
compile...

class Compiler:
    def __init__(self):
        self.ff = ff.new() # or whatever
    def __call__(self, source, filename, start_symbol):
        code = compile(source, filename, start_symbol, self.ff)
        self.ff.merge(code.co_flags)
        return code

Cheers,
M.

-- 
  Like most people, I don't always agree with the BDFL (especially
  when he wants to change things I've just written about in very 
  large books), ... 
         -- Mark Lutz, http://python.oreilly.com/news/python_0501.html