Metadata-Version: 2.1
Name: x-python
Version: 1.0.1
Summary: Python cross-version byte-code interpeter
Home-page: http://github.com/rocky/xpython
Author: Rocky Bernstein, Ned Batchelder, Paul Swartz, Allison Kaptur and others
Author-email: rb@dustyfeet.com
License: UNKNOWN
Description: |TravisCI| |CircleCI|
        
        x-python
        --------
        
        This is a C Python interpreter written Python.
        
        You can use this to:
        
        * Learn about how the internals of CPython works since this models that
        * Use as a sandboxed environment inside a debugger for trying pieces of execution
        * Have one Python program that runs multiple versions of Python bytecode.
          For example running Python 2.5 or 2.6 bytecode from Python 3.7.
          No need to install Python 2.6!
        
        The sandboxed environment in a debugger I find interesting. Since
        there is a separate execution, and traceback stack, inside a debugger
        you can try things out in the middle of a debug session without
        effecting the real execution. On the other hand if a sequence of
        executions works out, it is possible to copy this (under certain
        circumstances) back into CPython's execution stack.
        
        Going the other way, I may at some point hook in `my debugger
        <https://pypi.python.org/pypi/trepan3k>`_ into this interpreter and then
        you'll have a conventional pdb/gdb like debugger also with the ability
        to step bytecode instructions.
        
        Status:
        +++++++
        
        Currently only Python 2.5 - 2.7, and 3.2 - 3.5 bytecode is well
        understood.  Other versions will start to appear with the help of
        `xdis <https://pypi.python.org/pypi/xdis>`_.
        
        Whereas *Byterun* was a bit loose in accepting bytecode opcodes that
        is invalid for particular Python but may be valid for another;
        *x-python* is more stringent. This has pros and cons. On the plus side
        *Byterun* might run certain Python 3.4 bytecode because the opcode
        sets are similar. However starting with Python 3.5 and beyond the
        likelihood gets much less because, while the underlying opcode names
        may be the same, the semantics of the operation may change
        subtely. See for example
        https://github.com/nedbat/byterun/issues/34.
        
        Internally Byterun needs the kind of overhaul we have here to be able
        to scale to support bytecode for more Pythons, and to be able to run
        bytecode across different versions of Python. Specifically, you can't
        rely on Python's `dis <https://docs.python.org/3/library/dis.html>`_
        module if you expect to expect to run a bytecode other than the
        bytecode that the interpreter is running.
        
        In *x-python* there is a clear distinction between the version being
        interpreted and the version of Python that is running. There is
        tighter control of opcodes and an opcode's implementation is kept for
        each Python version. So we'll warn early when something is
        invalid. You can run 3.3 bytecode using Python 3.7 (largely).
        
        The "largely" part is because the interpreter has always made use of
        Python builtins. When a Python version running the interperter matches a
        supported bytecode close enough, the interpreter can (and does) make use
        interpreter internals. For example, built-in functions like `range()`
        are supported this way.
        
        However running 2.7 bytecode on 3.x is often not feasible since the
        runtime and internal libraries used like `inspect` are too different.
        
        I would say this is more than a a simple toy interpreter, but it will
        never be as complete as CPython or PyPy.
        
        
        History
        +++++++
        
        This is a fork of *Byterun.* which is a pure-Python implementation of
        a Python bytecode execution virtual machine.  Net Batchelder started
        it (based on work from Paul Swartz) to get a better understanding of
        bytecodes so he could fix branch coverage bugs in coverage.py.
        
        .. |CircleCI| image:: https://circleci.com/gh/rocky/x-python.svg?style=svg
            :target: https://circleci.com/gh/rocky/x-python
        .. |TravisCI| image:: https://travis-ci.org/rocky/x-python.svg?branch=master
        		 :target: https://travis-ci.org/rocky/x-python
        
        
Platform: UNKNOWN
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3.2
Classifier: Programming Language :: Python :: 3.3
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
Description-Content-Type: text/x-rst
